crohn's disease: how to make radiological interpretation -...

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SF 04-01 Rediscover the tube 14:00 - 14:20 Grand Ballroom 104

Chairperson(s): Byung Ihn Choi Chung-Ang University Hospital, Korea Kyung Sook Shin Chungnam National University Hospital, Korea

Crohn's disease: How to make radiological interpretation - updated consensus

Seong Ho Park University of Ulsan College of Medicine, Asan Medical Center, Korea. [email protected]

CTE and MRE are widely used in the management of CD and are highly accurate for diagnosing bowel inflammation and complications in CD. However, it appears that there is still substantial heterogeneity and inconsistency in how the examinations are interpreted and reported, both between different readers within the same institution and across different institutions. Both quality and consistency in the interpretation and reporting of imaging examinations are crucial for advancing patient care especially for the management of chronic diseases such as CD. The Society of Abdominal Radiology (SAR) CD-focused panel, in collaboration with

the American Gastroenterological Association (AGA), has recently developed consensus recommendations for the evaluation and interpretation of CTE and MRE in CD patients. The recommendations list the small bowel imaging findings that should be evaluated and define and describe key imaging findings that relate to the diagnosis, severity, and type of CD involvement on CTE and MRE. In this lecture, the speaker elaborates on some practical aspects of these recommendations regarding the interpretation of bowel inflammatory severity and strictures in CD.

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Stomach imaging: Update

Jin Woong Kim Chonnam National University Hwasun Hospital, Korea. [email protected]

In the gastrointestinal tract, especially, stomach imaging is still challenging in the radiology because of its distensibility, strong peristalsis and the role of endoscopy (EGD) with EUS, compared to small and large bowel. Fluoroscopy, CT and MRI among imaging modalities are being used for stomach imaging. Recently, the role of fluoroscopy is generally limited in evaluation of gastric passage and postoperative leakage, and the past role of fluoroscopy is replaced by EGD. CT is a main tool for evaluating specific diseases like subepithelial lesions and gastric cancer. MRI is being studied to overcome its limitations for gastric imaging caused from strong peristalsis of the stomach and relatively low spatial resolution of MR for small mucosal lesion such as early gastric cancer (EGC). In this article, we discuss the techniques and roles of CT that are mainly used in gastric imaging, and discuss new imaging techniques currently being tried.

CT gastrography

1. Overview of CT gastrography

Multidetector CT (MDCT) gastrography is a novel and useful technique for the preoperative imaging of gastric cancer. The MDCT gastrography (CTG) is a powerful tool for the detection of gastric cancer, especially EGC, mainly due to its ability to produce various three-dimensional (3D) images such as virtual gastrography (VG), shaded surface display (SSD), and tissue transition projection (TTP) images. According to previous reports, 3D CTG can improve the detectability of EGC as compared to two-dimensional (2D) CT imaging. VG images, which are generated using a surface volume-rendering technique, simulate a EGD by providing a view inside the gastric lumen. The SSD and TTP images are similar to single-contrast and double-contrast barium studies, respectively, and can provide a global view of the stomach and the exact location of a gastric lesion.

2. Virtual gastroscopy

VG are known to be superior to 2D cross-sectional images in finding subtle mucosal lesions like EGC. Especially in endoscopic-diagnosed EGC, 90% of lesions not found in 2D images are found in 3D images. Therefore, VG is particularly useful for the staging of stomach cancer. In addition, the location of the stomach cancer is important to determine surgical margin to achieve a safety margin greater than 5 cm. In this case, the location of stomach cancer is more easily and accurately found in VG images.

The endoscopic location of EGC may vary in accuracy depending on the skill of the endoscopist. In addition, the location of the EGC determined by EGD is diagnosed in the state of being expanded twice as large as that of the stomach during surgery, so the location of the stomach cancer may be different from that of the operation. On the other hand, CTG is inflated to almost the same extent as in surgery, which is advantageous for more accurate localization of gastric lesion.vi

3. Technical factors in CT gastrography

CTG refers to a multiplanar reformatted image including axial, sagittal, and coronal images and VG image, and CT images are obtained with a high resolution thin slice. In order to obtain such an image, it is necessary to expand the stomach appropriately. Air and water are mainly used for this purpose, but a VG image cannot be obtained when water is used, and recently, air is mainly used for gastric distention. To distend stomach with air, use oral administration of effervescent granule. Because the stomach has a very long and powerful peristalsis, unlike other gastrointestinal tract, spasmolytics (buscopan) was administered to maintain the hypotonia before performing CT scan. Recently, the CT scan is enough fast to obtain good images without using spasmolytics.

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To distend the stomach, patients usually ingest 6 g of effervescent granules with 5-10 mL of water just prior to undergoing CT scanning. Patients are then placed in the left lateral decubitus position to shift the gastric contents from the lower two-thirds of the stomach to the fundus; they are then immediately placed on the scanning table in the 30° left posterior oblique (LPO) position by putting a pillow under the right back. If a gastric lesion is at the cardia or fundus, a right lateral decubitus position should be used instead of the LPO position. An initial scout image is obtained to make sure that the stomach is adequately distended.

Most pat ients in Korea undergo EGD before performing CTG. Therefore, CT is performed after taking appropriate position according to the lesion location of endoscopic results before CT. In obtaining 3D CT images using raw data of CT, obtaining VG images using the endoscopic images of the lesion as a reference can increase the detection rate and diagnostic accuracy of the gastric lesion. This is the typical difference between CTG and CT colonography. Due to the specificity of this situation, good images of CTG can be obtained by an experienced technician alone can obtain, and the radiologists can reduce their burden and time in manual creation of VG. Methods for obtaining VG images can be divided into two methods: Automatically-generated CTG and technician-generated CTG according to routine protocol along lesser and greater curvatures.

4. Tumor staging of gastric cancer

Recent study by Kim et al. postulated that the inner and the outer halves of the low-density-stripe layer on contrast-enhanced CT images might represent the

submucosal and the proper muscle layer, respectively, according to the radiologic-pathologic correlation. They suggested New MDCT criteria based on their own speculation regarding the gastric mural layering, in which there are major differences in MDCT criteria for T1b and T2 cancers. When the low-density-stripe layer is disrupted to a degree of less than 50% of the thickness, the tumor is staged as T1b. T2 tumors show disruption of the low-density-stripe layer (greater than 50% of the thickness) without abutting on the outer, slightly higher-attenuating layer (Table 1).

Unfortunately, gastric wall is often not showed as typical three-layer structure on CT gastroscopy. In this cases, New MDCT criteria by Kim et al. cannot be applied. Thus, in this cases, conventional MDCT criteria can be used for gastric cancer staging (Table 2). Conventional gastric cancer MDCT criteria postulated distinguishing T2 from T1 is whether enhancing mass or wall thickening is more than half of entire gastric wall thickness or not. The concepts of these two criteria are similar in terms of that submucosa and mucosal layer has similar thickness and sum of these two layer consists of almost of entire gastric wall thickness.

5. Current issues of gastric imaging

1) Restaging of gastric cancer after chemotherapy

Tumor restaging and determination of resectability on MDCT after chemotherapy is critical to determine treatment planning and prediction of patients’ prognosis. A recent study by Joo et al. proposed new MDCT imaging criteria for gastric cancers after chemotherapy. The characteristic of this criteria is that non-enhancing

Table 1. New MDCT criteria for the tumor staging of gastric cancer. Adopted from Eur Radiol 2012;22:654-662

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perigastric infiltration does not affect T-staging in order to minimize the over-estimation of tumor extent due to chemotherapy-related edema or fibrosis.

2) CT volumetry

Lymphovascular invasion is considered as an independent factor for lymph node metastasis and the prognosis of resectable gastric cancer patients. A recent study by Chen et al. reported that gross tumor volume of resectable gastric adenocarcinoma at MDCT

demonstrated capability in predicting lymphovascular invasion and distinguishing T-stages.

Conclusion

Multidetector CT gastrography has been still regarded as a promising technique in evaluating gastric lesions including staging of gastric cancers and subepithelial lesions because CT gastroscopy has the ability to show not only details of gastric mucosal change but also extramural findings. High-quality CTG images,

Table 3. New post-chemotherapy MDCT imaging criteria for the tumor staging of gastric cancer. Adopted from Abdom Radiol 2017;42:2807-2815

Table 2. Conventional MDCT imaging criteria for the tumor staging of gastric cancer.

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including various 3D images, can help clinicians plan optimal treatment strategies by offering a global view of the stomach with the exact localization of the tumor and accurate tumor staging. In addition, routine CTG along lesser and greater curvature created by an experienced technician can provide good images of VG for gastric evaluation and reduce radiologist’s burden. Non-enhancing perigastric infiltration (chemotherapy-related edema or fibrosis) does not affect T-staging after chemotherapy for gastric cancer in order to minimize the over-estimation of tumor extent.

References

1. Kim JW, Shin SS, Heo SH, Lim HS, Lim NY, Park YK, et al. The role of three-dimensional multidetector CT gastrography in the preoperative imaging of stomach cancer: emphasis on detection and localization of the tumor. Korean J Radiol 2015;16:80-89

2. Kim JW, Shin SS, Heo SH, Choi YD, Lim HS, Park YK, et al. Diagnostic performance of 64-section CT using CT gastrography in preoperative T staging of gastric cancer according to 7th edition of AJCC cancer staging manual. Eur Radiol 2012;22:654-662

3. Lee IJ, Lee JM, Kim SH, Shin CI, Lee JY, Kim SH, et al. Diagnostic performance of 64-channel multidetector CT in the evaluation of gastric cancer: differentiation of mucosal cancer (T1a) from submucosal involvement (T1b and T2). Radiology 2010;255:805-814

4. Shen Y, Kang HK, Jeong YY, Heo SH, Han SM, Chen K, et al. Evaluation of early gastric cancer at multidetector CT with multiplanar reformation and virtual endoscopy. Radiographics 2011;31:189-199

5. Choi JI, Joo I, Lee JM. State-of-the-art preoperative staging of gastric cancer by MDCT and magnetic resonance imag ing . Wor ld J Gas t roen te ro l 2014;20:4546-4557

6. Jeong SH, Bae K, Ha CY, Lee YJ, Lee OJ, Jung WT, et al. Effectiveness of endoscopic clipping and computed tomography gastroscopy for the preoperat ive localization of gastric cancer. J Korean Surg Soc 2013;84:80-87

7. Park HS, Lee JM, Kim SH, Lee JY, Yang HK, Han JK, et al. Three-dimensional MDCT for preoperative local staging of gastric cancer using gas and water distention methods: a retrospective cohort study. AJR Am J Roentgenol 2010;195:1316-1323

8. Kim JH, Eun HW, Choi JH, Hong SS, Kang W, Auh YH. Diagnostic performance of virtual gastroscopy using MDCT in early gastric cancer compared with 2D axial CT: focusing on interobserver variation. AJR Am J Roentgenol 2007;189:299-305

9. Chen CY, Hsu JS, Wu DC, Kang WY, Hsieh JS, Jaw TS, et al. Gastric cancer: preoperative local staging with 3D multi-detector row CT--correlation with surgical and histopathologic results. Radiology 2007;242:472-482

10. Kim HJ, Kim AY, Oh ST, Kim JS, Kim KW, Kim PN, et al. Gastric cancer staging at multi-detector row CT gastrography: comparison of transverse and volumetric CT scanning. Radiology 2005;236:879-885

11. K im AY, K im HJ , Ha HK. Gas t r i c cancer by multidetector row CT: preoperative staging. Abdom Imaging 2005;30:465-472

12. Washington K. 7th edition of the AJCC cancer staging manual: stomach. Ann Surg Oncol 2010;17:3077-3079

13. Furukawa K, Miyahara R, Itoh A, Ohmiya N, Hirooka Y, Mori K, et al. Diagnosis of the invasion depth of gastric cancer using MDCT with virtual gastroscopy: comparison with staging with endoscopic ultrasound. AJR Am J Roentgenol 2011;197:867-875

14. Ahn HS, Kim SH, Kodera Y, Yang HK. Gastric cancer staging with radiologic imaging modalities and UICC staging system. Dig Surg 2013;30:142-149

15. Joo I, Kim SH, Ahn SJ, Lee ES, Shin CI, Lee HJ, et al. Preoperative tumor restaging and resectability assessment of gastric cancers after chemotherapy: diagnostic accuracy of MDCT using new staging criteria. Abdom Radiol (NY) 2017;42:2807-2815

16. Chen XL, Pu H, Yin LL, Li JR, Li ZL, Chen GW, et al. CT volumetry for gastric adenocarcinoma: association with lymphovascular invasion and T-stages. Oncotarget 2018;9:12432-12442

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Small bowel imaging: Update

Se Hyung Kim Seoul National University Hospital, Korea. [email protected]

Traditionally, cross-sectional imaging modalities, such as computed tomography (CT), magnetic resonance (MR) imaging, and ultrasound (US), have been employed in the diagnosis, staging, and follow-up of patients with inflammatory bowel disease (IBD). It has been reported that cross-sectional imaging has a high diagnostic accuracy in the assessment of Crohn’s disease (CD) by comparing it with histopathological, surgical, and endoscopic examination. These previous studies have established the role of conventional cross-sectional imaging in the assessment of CD activity. Recent studies have focused on the detection and quantification of intestinal fibrosis associated with CD using cross-sectional imaging as well as on monitoring of IBD activity. Quantification of intestinal fibrosis is crucial; if fibrosis is predominant, then endoscopic

dilatation of the stricture or surgery is necessary whereas if inflammation is predominant, then medical therapy is selected. Fibrosis and inflammation often coexist in CD and it is difficult to differentiate fibrosis from inflammation because there are overlaps between these two conditions in conventional imaging findings. Therefore, the diagnosis of fibrosis using cross-sectional imaging remains a challenge.

Even though monitoring of IBD after treatment is critically important, the optimal method for monitoring disease in patients with IBD is yet to be determined. Endoscopic evaluation with ileocolonoscopy is the gold standard but is invasive, costly, and time-consuming. In this regard, cross-sectional imaging modalities such as CEUS, CT, or MRI can be helpful for monitoring after treatment.

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Rectal imaging: Update

Min Ju Kim Korea University Anam Hospital, Korea. [email protected]

Colorectal cancer is the third most common malignancy worldwide, and the rectal cancer demonstrates for 29% of all cases (1). Local staging of rectal cancer is very important for the addressing patients to surgery or to preoperative chemoradiotherapy after total mesorectal excision (TME) appropriately. The result of combined chemoradiotherapy and surgery may affect rectal function negatively, so other approaches have been proposed as an alternative to TME for patients showing a good clinical response on restaging after chemoradiotherapy.

The advanced MRI performed at a higher field strength benefits from higher spatial resolution, faster image acquisition, and higher signal-to-noise ratio (SNR), which may result in better resolution of rectal wall. MRI plays a major role in assessing the extent of rectal cancer at staging and restaging scans. New pelvic phased-array multichannel coils could provide high spatial resolution, higher SNR, and larger FOV imaging for better depiction of the lateral pelvic lymph nodes and structures (2-5).

Rectal MRI has a fundamental role in the local staging and restaging of rectal cancer. Recently, PET/MRI enables a multiplanar high resolution morphological study of pelvis, providing important information of cell density and metabolic activity with diffusion-weighted imaging (DWI) and 18F fluorodeoxyflucose uptake (1, 5, 6).

Recently, the updated recommendations for magnetic resonance imaging for clinical management of rectal cancer, for example, Updated recommendations from the 2016 European Society of Gastrointestinal and Abdominal Radiology (ESGAR) consensus meeting (7). It is consisted of MR imaging acquisition, MR imaging evaluation and reporting, and MRI performances. There were items lacking consensus such as patient preparation, DWI, and MRI reporting.

MRI is the modality of choice for staging rectal cancer to assist surgeons in obtaining complete resection margins. Therefore, we should aware the updated imaging method or sequences, and recommended guidelines for rectal cancer management and imaging.

Proper optimization of rectal MRI protocol is very important for accurate staging of rectal cancer and evaluation of anorectal disease.

References

1. Crimi F, Lacognata C, Cecchin D, Zucchetta P, Pomerri F. Rectal cancer staging: An up-to-date pictorial review. J Med Imaging Radiat Oncol 2018 [Epub ahead of print]

2. Fusco R, Petrillo M, Granata V, Filice S, Sansone M, Catalano O, et al. Magnetic resonance imaging evaluation in neoadjuvant therapy of locally advanced rectal cancer: A systematic review. Radiol Oncol 2017;51:252-262

3. Moreno CC, Sullivan PS, Kalb BT, Tipton RG, Hanley KZ, Kitajima HD, et al. Magnetic resonance imaging of rectal cancer: staging and restaging evaluation. Abdom Imaging 2015;40:2613-2629

4. Kennedy E, Vella ET, Blair Macdonald D, Wong CS, McLeod R, Cancer Care Ontario Preoperative Assessment for Rectal Cancer Guideline Development Group. Optimisation of preoperative assessment in patients diagnosed with rectal cancer. Clin Oncol (R Coll Radiol) 2015;27:225-245

5. Jhaveri KS, Hosseini-Nik H. MRI of rectal cancer: An overview and update on recent advances. AJR Am J Roentgenol 2015;205:W42-55

6. Paspulati RM, Partovi S, Herrmann KA, Krishnamurthi S, Delaney CP, Nguyen NC. Comparison of hybrid FDG PET/MRI compared with PET/CT in colorectal cancer staging and restaging: a pilot study. Abdom Imaging 2015;40:1415-1425

7. Beets-Tan RGH, Lambregts DMJ, Maas M, Bipat S, Barbaro B, Curvo-Semedo L, et al. Magnetic resonance imaging for clinical management of rectal cancer: Updated recommendations from the 2016 European Society of Gastrointestinal and Abdominal Radiology (ESGAR) consensus meeting. Eur Radiol 2018;28:1465-1475

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SF 11-01 Pancreas: Revisited 14:00 - 14:20 Grand Ballroom 102

Chairperson(s): Joon Koo Han Seoul National University College of Medicine, Korea Kyung Seung Oh Kosin University Gospel Hospital, Korea

Imaging modality of the pancreas: Update

Dong Ho Lee Seoul National University Hospital, Korea. [email protected]

In this 20 minute-talk, I would like to briefly review the current status of various imaging modalities for pancreas with recent advances.

1. US

Evidently, US would be the best imaging modality for screening of pancreas disease due to non-invasiveness, wide availability and lack of radiation exposure. However, there have been continuous challenge in evaluation of pancreas using US owing to poor sonic window from retroperitoneal location as well as operator dependency. To overcome this transabdominal US, endoscopic ultrasound (EUS) has been emerged as attractive tool for evaluation of pancreatic disease, and several studies with meta-analysis have been reported that EUS could be used as screening tool for pancreatic cancer in high risk population. With the recent advances in imaging technology, pancreatic cyst has increasingly been found on imaging study incidentally. As some pancreatic cyst can progress into pancreatic cancer, follow-up for some pancreatic cyst should be done. For the follow-up of pancreatic cyst, transabdominal US could be the best tool, and I would like to discuss the role of transabdominal US for pancreatic cyst follow-up with recent publication.

2. CT

CT has been the standard imaging modality for evaluation of pancreatic disease, especially for pancreatic cancer mainly owing to high spatial resolution, and NCCN guideline for pancreatic cancer management recommends pancreatic protocol CT is the first imaging modality for evaluation of pancreatic cancer patients. However, about 10-15% of pancreatic cancer could be iso-dense, and therefore, detection of this iso-attenuated pancreatic cancer using CT would be somewhat limited. In addition, radiation exposure from CT scan has been a problem, especially for the screening test. Recently, low tube voltage CT scan usually using 80 kVp has been shown to increase CNR in pancreatic cancer imaging as well as to reduce the radiation dose. I would like to discuss the benefit of low tube voltage CT scan with several recent publications. Also, dual energy CT scan has been introduced in pancreatic imaging, and I would like to briefly touch on the potential benefit and application of dual energy CT in pancreatic imaging.

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Pancreatic cystic tumor: Update

Sang Soo Shin Chonnam National University Hospital, Korea. [email protected]

Pancreatic cystic neoplasms (PCN) are estimated to be present in 2-45% of the general population. PCN comprise a clinically challenging entity as their biological behavior ranges from benign to malignant disease. Consequently, correct management of PCN may prevent progression to pancreatic cancer while minimizing the need for lifelong screening and related costs. Unfortunately, it is often difficult to differentiate between the various types of PCN. There are two major aspects to the effective diagnosis and management of PCNs. The first is the differentiation between pancreatic cystic neoplasms and pancreatic pseudocysts. Originally, inflammatory pseudocysts were felt to account for the majority of pancreatic cysts. However with the increased use of high resolution abdominal imaging, especially in asymptomatic individuals, especially those without a history of pancreatitis, it is becoming obvious that these neoplastic pancreatic cysts are far more common than pancreatic pseudocysts. The other major component of the effective diagnosis of pancreatic cystic neoplasms is the understanding of the underlying pathologies of pancreatic cystic neoplasms, their varying degrees of malignant risk, and the role of imaging and cyst fluid analysis in sorting these issues out.

The most common cystic pancreatic neoplasms are IPMNs, MCNs, and serous cystadenomas (SCAs). Although SCAs are considered benign, IPMNs and MCNs have malignant potential. Other cystic pancreatic lesions account for fewer than 10% of cases and include uncommon pathologic findings such as solid pseudopapillary neoplasms, cystic pancreatic neuroendocrine neoplasms, cystic degeneration in other solid pancreatic neoplasms, lymphoepithelial cysts, and cystic adenocarcinoma of the pancreas.

Imaging plays a crucial role in the management of cystic lesions of the pancreas, including lesion detection and characterization. Technologic innovations in MDCT and MRI have led to improvement in analysis and morphologic differentiation of cystic pancreatic

lesions and are widely considered the primary imaging modalities in the care of patients with cystic lesions of the pancreas. In addition, advances in postprocessing have enabled enhanced definition of the extent of a lesion and its relation to adjacent structures. These techniques are particularly valuable in delineating the relation between the cystic lesion and the pancreatic duct, a key feature in differentiating side branch IPMNs from other cystic lesions.

Optimal management of cystic pancreatic lesions begins with morphologic classification into one of four types: unilocular, microcystic, macrocystic, and cysts with solid components. Unilocular cysts are thin walled simple cystic lesions without internal septa, solid components, or calcifications. Pseudocysts are the most common lesion in this category, and usually, features of pancreatitis, such as inflammation, atrophy, and pancreatic parenchymal calcifications, are also seen. In rare instances, IPMNs, SCAs (< 10%), MCNs, and lymphoepithelial cysts present as unilocular cysts. Microcystic lesions typically present with multiple tiny cysts (more than six, each measuring < 2 cm) with lobulated outlines and thick or fleshy stroma. The microcystic appearance is typically seen in SCAs, and the pathognomic fibrous central scar is present in only 30% of cases. Microcystic lesions can have avid enhancement on arterial phase images after IV contrast injection owing to the presence of a vascular epithelial lining. This effect is especially pronounced in lesions with a very small cyst size, causing them to masquerade as solid pancreatic neoplasms such as neuroendocrine tumors and metastatic lesions from a primary cancer such as renal cell carcinoma or melanoma. Delayed phase contrast-enhanced images can show the microcysts and the enhancing stroma. Similarly, T2-weighted MR images can confirm the presence of high-signal-intensity microcysts. Most SCAs have a microcystic appearance on images. Oligocystic and macrocystic patterns of SCA have been described

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in fewer than 10% of patients, and they can be difficult to differentiate from mucinous neoplasms on imaging. Macrocystic lesions are composed of fewer cysts than are microcystic lesions, and the cysts are often larger than 2 cm in diameter. MCNs and side-branch IPMNs are included in this category. Patient demographics (age, sex) and presence or absence of cyst communication can be used to differentiate MCNs and side-branch IPMNs. MCNs are common among middle-aged women, are usually well defined, and are often located in the pancreatic tail. Side-branch IPMNs are commonly detected in older men and are more frequently located in the proximal pancreas (head and uncinate process). An important differentiating feature between MCN and IPMN is visualization of pancreatic ductal communication. If a clear channel of communication

with the pancreatic duct is visualized, the diagnosis of side-branch IPMN is almost certain because SCAs and MCNs do not communicate with the pancreatic ductal system.

Cysts with solid components include true cystic tumors (MCNs, IPMNs) and solid pancreatic neoplasms associated with a cystic component, which includes tumors such as pancreatic neuroendocrine neoplasm, solid pseudopapillary neoplasm, adenocarcinoma of the pancreas, and metastatic lesions. Both MDCT and MRI can depict the presence of enhancing solid components in a cystic lesion, which is diagnostic for this category of lesions. The lesions encountered in this category are either frankly malignant or have high malignant potential. Therefore, surgical resection is the preferred management.

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Pancreatitis: Update

Hee Sun Park Konkuk University Medical Center, Korea. [email protected]

Acute pancreatitis

According to the revised Atlanta classification in 2012, acute pancreatitis is classified as interstitial edematous pancreatitis and necrotizing pancreatitis, and necrotizing pancreatitis is divided in parenchymal and peripancreatic necrosis. The terminology of peripancreatic collections has also changed in the revised Atlanta classification. In interstitial pancreatitis, peripancreatic collections are referred to as “acute pancreatic fluid collections (APFC)”, whereas in necrotizing pancreatitis it is called “acute necrotic collections (ANC)”. Acute collections either resolve or mature with encapsulation over time, which takes around 4-6 weeks. Acute peripancreatic collections become pseudocyst, and acute necrotic collections lead to walled off necrosis (WON). Imaging findings combined with the time course of the disease

usually allow distinction between the collections, and they facilitate the stratification among the different management planning.

Autoimmune pancreatitis

Autoimmune pancreatitis (AIP) is the pancreatic manifestation of IgG4-related sclerosing disease, and it is now recognized as a part of that disease spectrum. Extrapancreatic organs such as bile duct, gallbladder, kidneys, retroperitoneum, etc., may be involved in IgG4-related sclerosing disease. It shows exquisite response to corticosteroid therapy. Clinical, laboratory, and cross-sectional imaging modalities allow a noninvasive diagnosis in most of the patients. Usually MDCT and MRI with MRCP play an integral role in the diagnosis, surveillance, and management of patients with AIP.

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Update of pancreatic cancer

Hiroyuki Irie Saga University, Japan. [email protected]

Despite the recent advances in imaging modalities, diagnosis of pancreatic cancer is still challenging. Imaging evaluation plays a central and primary role in the initial decision-making process of patients with pancreatic cancer; however, diagnostic accuracy of pancreatic cancer has not been enough adequate.

There are several issues that we should recognize. In this session, I will talk mainly computed tomography (CT) and magnetic resonance (MR) imaging in diagnosing pancreatic cancer and refer PET-CT in detecting metastatic lesion and peritoneal implants briefly.

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Abdomen 13:30 - 18:00 Grand Ballroom 103

Liver: Single but not simple

Chairperson(s)Myeong-Jin Kim Yonsei University College of Medicine,

Severance Hospital, KoreaWon Jae Lee Samsung Medical Center, Sungkyunkwan

University School of Medicine, Korea

MC 02 AB-01 13:30 Performance of short protocol of non-contrast MRI for hepatocellular carcinoma surveillanceJin Sil Kim1, Jeong Kyong Lee1, Seung Yon Baek1, Hye IN Yun2 1Ewha Womans University School of Medicine, 2Ewha Womans University Mokdong Hospital, Korea. [email protected]

PURPOSE: To evaluate the per-patient diagnostic performance of minimized protocol of non-contrast MRI for hepatocellular carcinoma (HCC) surveillance.MATERIALS AND METHODS: Among 297 patients with liver MRI and risk for HCC over 8-years, 226 patients were finally included in this retrospective study after exclusion due to previous HCC treatment, inadequate follow-up, inadequate image or other disease. Two image sets from the first MRI in each patient were reviewed per patient: Set 1 consisted of diffusion-weighted imaging (DWI) and T2-weighted single-shot fast spin echo (SSFSE) images; Set 2 included T1-weighted in and opposed phase images and images from set 1. Image sets were scored as positive or negative for the presence of HCC according to the predetermined criteria. Final diagnosis was done by explantation (n = 21), resection (n = 15), biopsy (n = 40), image follow-up with or without TACE or RF ablation (n = 150). Diagnostic performances and sensitivities of two different sets and conjunction with AFP for detecting HCC were assessed and compared using McNemar test. Logistic regression was used for determining affecting factor for sensitivity.RESULTS: Sensitivity, specificity, positive predictive value, and negative predictive value of set 1 were 84.8% (145/171), 85.5% (47/55), 94.8% (145/153) and 64.4% (47/73), respectively. Those of set 2 were 86.5% (148/171), 76.4% (42/55), 92.0% (148/161) and 64.6% (42/65), respectively. Sensitivities of two sets were not significantly different (p = 0.4531). Sensitivities for set 1 and set 2 in conjunction with alpha-fetoprotein was higher than that of MRI alone (Set 1 with AFP, 87.7% [150/171], p = 0.0625; 90.1% [154/171], p = 0.0313, respectively). In very early stage HCCs (single nodule

smaller than 2 cm), sensitivities of set 1 and set 2 was 72.5% (37/51) and 74.5% (38/51). Logistic regression analysis demonstrated that perihepatic ascites and size less than 2 cm was significantly associated with sensitivity (OR, 11.6 and 2.7; p = 0.0014 and p = 0.0409, respectively).CONCLUSION: A minimized protocol of non-contrast MRI consisting of T2-weighted SSFSE and DWI has high sensitivity and may be an acceptable method for HCC surveillance. The inclusion of T1-weighted in and opposed phase and AFP could increase sensitivity of the protocol.

MC 02 AB-02 13:40 Intraindividual comparison of nonenhanced MRI, abbreviated MRI with gadoxetic acid, and US for HCC screening in patients at high risk of HCC in a prospective cohortHyo Jung Park, So Yeon Kim, Hye Young Jang, So Jung Lee, Hyung Jin Won, Jae Ho Byun, Moon-Gyu Lee Asan Medical Center, Korea. [email protected]

PURPOSE: To compare the pe r fo rmance o f nonenhanced MRI (NE-MRI), abbreviated MRI (A-MRI) including hepatobiliary phase imaging, and ultrasonography (US) as a screening tool for HCCs in a prospective cohort.MATERIALS AND METHODS: The study cohort consisted of 386 patients with an estimated annual risk of HCC > 5% who underwent screening tests with paired gadoxetic acid-enhanced MRI in a prospective cohort enrolled between 2011 and 2013. NE-MRI set was composed of T2WI and DWI. A-MRI set included hepatobiliary phase imaging in addition to the same sequences of NE-MRI. The NE-MRI sets were considered positive when a lesion ≥ 10-mm showed mild to moderate T2 hyperintensity or diffusion restriction. The A-MRI sets were considered positive when a lesion with a size ≥ 10-mm showed hypointensity on hepatobiliary phase imaging, or mild to moderate T2 hyperintensity, or diffusion restriction. Any lesion showing very bright T2 signal intensity on T2WI was not regarded as positive. On US, a discrete lesion ≥ 10-mm or suspicious tumor thrombus was regarded positive. Diagnosis of HCC was based on pathology and/or typical findings of HCC on dynamic contrast-enhanced CT obtained within 3-months after MRI exams. Per-lesion sensitivity, per-exam sensitivity and per-exam specificity were compared among the three imaging sets using the McNemar test with generalized estimating equations.RESULTS: A total of 32 HCCs were diagnosed in 28

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patients (6.9%). Per-lesion and per-exam sensitivity of NE-MRI, A-MRI, and US were 87.5%, 100%, and 34.4%, respectively, and 89.3%, 100%, and 39.3%, respectively. Both NE-MRI and A-MRI showed better per-lesion and per-exam sensitivity than US (p < 0.001), while there was no significant difference between the NE-MRI and A-MRI (p ≥ 0.25). As for per-exam specificity, A-MRI (84.4%) showed poorer results compared to NE-MRI with statistical significance (93.0%, p < 0.001) and poorer results than US (93.6%) though not statistically significant (p = 0.08). The per-exam specificity of NE-MRI and US did not significantly differ (p > 0.999).CONCLUSION: NE-MRI is a promising option for HCC screening in patients at high risk of HCC, as it showed better sensitivity compared to US and better specificity compared to A-MRI. A-MRI including the hepatobiliary phase showed a perfect sensitivity with a compromised specificity.

MC 02 AB-03 13:50 A prospective cohort study to compare biannual low dose liver CT and US for HCC surveillance in high-risk group of HCC: Preliminary studyJeong Hee Yoon1, Jeong Min Lee2, Dong Ho Lee1, Ijin Joo1, Sujoa Ahn1, Joon Koo Han2

1Seoul National University Hospital, 2Seoul National University College of Medicine, [email protected]

PURPOSE: To compare sensitivity for hepatocellular carcinoma (HCC) of bi-annual ultrasonography (US) and low dose computed tomography (LDCT) in patients at high risk of HCC.MATERIALS AND METHODS: In this IRB-approved prospective ongoing study, 138 patients have been enrolled and informed consent was obtained from all patients. Eligibility criteria were a) high risk group of HCC on surveillance, b) no history of HCC, c) risk index ≥ 2.33 which suggests the estimated annual risk of developing HCC more than 5%, and d) no contraindication of

contrast enhanced CT. Patients underwent paired biannual US and two phase-LDCT once to three times during one year follow-up. Twelve patients withdrew after the 1st or 2nd CT examinations. Two-phase LDCT includes arterial and 3 minute delayed phases covering the liver and the spleen, and a combination of low kVp (80-100 kVp according to patients’ weight), automatic tube current control and hybrid iterative reconstruction were applied. The confirmation of HCC was done on histologic findings or typical imaging features on follow-up imaging or gadoxetic acid liver MRI. This interim analysis was performed in 98 patients with follow-up images more than 6 months (mean risk index, 3.38 ± 0.76). RESULTS: Twenty HCC was developed in 19.4% (19/98) patients, and the mean size of the tumor was 1.4 ± 0.5 cm (0.8-2.3 cm). On US, 31.6% (6/19) was detected, and 89.5% (17/19) HCCs were detected on LDCT (p < 0.0001). Specificity was 83.5% on US and 94.9% on LDCT. False positive was reported in 13 patients on US and 4 patients on LDCT, resulting in significant higher positive predictive value of LDCT (31.6% vs. 81.0%, p < 0.0001).CONCLUSION: Patients with risk index ≥ 2.33 showed high annual incidence of HCC development in our study, and two-phase LDCT showed significantly higher sensitivity and specificity than the standard care of HCC surveillance (US).

MC 02 AB-04 14:00 Comparison of diagnostic performance of non-contrast MRI and abbreviated MRI in initially diagnosed hepatocellular carcinoma patients: A simulation study of surveillance for hepatocellular carcinomasSunyoung Whang, Joon IL Choi, Moon Hyung Choi, Young Joon Lee, Sung Eun Rha, Eu Hyun Kim The Catholic University of Korea, Seoul St. Mary's Hospital, Korea. [email protected]

PURPOSE: To compare the diagnostic performance of non-contrast MRI and abbreviated MRI using gadoxetic acid for detecting hepatocellular carcinoma (HCC) in initially diagnosed, early stage HCC patients.MATERIALS AND METHODS: We identified 142 consecutive, initially diagnosed HCC patients within Milan criteria, who performed liver MRI between January 2015 and December 2016. For the control group, we enrolled 158 consecutive patients without HCC but had risk factors (liver cirrhosis, chronic hepatitis B or C) of HCC, who also performed liver MRI in the same period. Total number of HCCs was 177 and the number of HCCs smaller than 2 cm and 2 cm ≤ were 92 and 85,

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respectively. Two radiologists independently reviewed two MRI sets; non-contrast set and abbreviated set. Non-contrast set consists of T2 FSE/ssFSE with fat saturation, T1 in- and out-of-phase image, non-contrast 3D GRE T1 images, DWI (with b-value 500 s/mm2) and ADC map. Abbreviated set consists of T2 FSE/ssFSE with fat saturation, 3D GRE T1 images at hepatobiliary phase 20 minutes after gadoxetic acid injection, DWI and ADC map. Both reviewers recorded the presence, size and location of HCCs.RESULTS: In per-patient analysis, sensitivity of reader 1 of non-contrast and abbreviated set were 90.8% and 89.8%, respectively. Specificity of non-contrast and abbreviated set were 92.7% and 92.3%, respectively. For reviewer 2, sensitivity of both sets were 87.4% and 87.5%, and specificity were 90.3% and 91.7%, respectively. When comparing two image sets, there was no statistical difference in both reviewers (p = 0.65 and 0.86 for reviewer 1 and 2, respectively, using the MeNemar test). Kappa statistics showed excellent inter-observer agreement (0.86 for non-contrast and 0.84 for abbreviated set). In per-tumor analyses, sensitivity of reviewer 1 for non-contrast and abbreviated set were 81.9% and 83.1%. For reviewer 2, 80.8% and 83.6%, respectively.CONCLUSION: Non-contrast and abbreviated MRI using gadoxetic acid showed comparable diagnosing performance for detecting HCCs in early stage HCC patients.

MC 02 AB-05 14:10 Liver Imaging Reporting and Data System (LI-RADS) treatment response categorization: Added value of ancillary features on gadoxetic acid-enhanced MR imagingSewoo Kim1, Ijin Joo1, Hyo Cheol Kim1, Su Joa Ahn1, Hyo-Jin Kang1, Sunkyung Jeon1, Joon Koo Han2 1Seoul National University Hospital, 2Seoul National University College of Medicine, [email protected]

PURPOSE: To investigate the added value of ancillary features (AFs) in the Liver Imaging Reporting and Data System (LI-RADS) treatment response (LR-TR) categorization to the conventional enhancement-based criteria on gadoxetic acid-enhanced liver MR imaging (Gd-EOB-MRI).MATERIALS AND METHODS: This retrospective study included 207 patients with Gd-EOB-MRI after locoregional treatment for hepatocellular carcinoma (HCC) and a reference standard for marginal recurrence (viable, n = 107; non-viable, n = 100). For the treated observations, two independent radiologists assigned LR-TR categories (LR-TR nonviable, equivocal, or

viable) according to different criteria: i) conventional, ii) TP-included: including transitional phase (TP) for determining washout, iii) AF-applied: applying AFs on hepatobiliary phase, diffusion-weighted imaging, and T2-weighted imaging for category adjustment. Diagnostic performances of conventional and modified criteria were compared using the McNemar test.RESULTS: For the diagnosis of marginal recurrence, “LR-TR v iable” of AF-appl ied cr i ter ia showed significantly higher sensitivity; and accuracy (88.8% [95/107] and 86.0% [92/107]; 92.8% [192/207] and 90.8% [188/207] in reviewers 1 and 2, respectively) than that of conventional (64.5% [69/107] and 39.3% [42/107]; 80.7% [167/207] and 67.6% [140/207]) or TP-included criteria (77.6% [83/107] and 55.1% [59/107]; 87.4% [181/207] and 74.9% [155/207]) in both reviewers (ps < 0.05). However, the specificities were comparable between criteria (conventional: 98.0% [98/100] and 98.0% [98/100]; TP-included: 98.0% [98/100] and 96.0% [96/100]; AF-applied: 97.0% [97/100] and 96.0% [96/100] in reviewers 1 and 2, respectively) (ps > 0.05). “LR-TR equivocal” was less frequently assigned on AF-applied criteria (1.4% [3/207] and 7.2% [15/207] in reviewers 1 and 2, respectively) than conventional; or TP-included criteria (18.4% [38/207] and 35.3% [73/207]; 7.7% [16/207] and 25.7% [53/207]).CONCLUSION: By applying ancillary features in the LR-TR category adjustment on Gd-EOB-MRI, more sensitive and confident diagnosis of recurred HCC can be achieved than conventional enhancement-based criteria.

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MC 02 AB-06 14:20 Washout appearance on gadoxetic acid-enhanced MRI: Should it be confined to the portal-venous phase? Dong Hwan Kim, So Yeon Kim, Sang Hyun Choi, Seung Soo Lee, Jae Ho Byun, Moon-Gyu Lee Asan Medical Center, Korea. [email protected]

PURPOSE: To determine which dynamic phase(s) of gadoxetic acid-enhanced MRI is most suitable to evaluate "washout" appearance in the diagnosis of hepatocellular carcinoma (HCC).MATERIALS AND METHODS: Among 888 patients at risk of HCC under the ultrasonography (US) surveillance in 2012 who underwent gadoxetic acid-enhanced MRI as a further workup for a lesion detected on US, 178 patients with surgically-confirmed 203 hepatic nodules 3.0 cm or smaller were included in our study. The 203 nodules consisted of 186 HCCs, 6 dysplastic nodules, and 11 other malignancies (8 intrahepatic cholangiocarcinomas, 1 combined HCC and cholangiocarcinoma, and 2 metastases). According to the phases in which the washout appearance was observed, three different diagnostic MRI criteria of HCC were defined, which were arterial phase hyperenhancement and hypointensity (1) only on the portal-venous phase (PVP) as the washout confined to PVP; (2) on the PVP or transitional phase (TP) as the extended washout to TP; or (3) on the PVP or TP, or hepatobiliary phase (HBP) as the extended washout to HBP. If the nodule showed marked T2 high signal intensity, a rim enhancement, or targetoid appearance, we precluded it from the diagnosis of HCC. Two abdominal radiologists retrospectively reviewed MRI scans and determined whether or not the nodule showed hypointensity relative to surrounding liver tissue on the PVP, TP, and HBP images, respectively. The sensitivity and specificity with 95% confidence interval (CI) for each criterion were calculated and compared by using generalized estimating equations models to address data clustering.RESULTS: Among the three different washout criteria, the washout appearance extended to HBP provided the best sensitivity (95.2% [95% CI, 91.2-97.4%]) compared to the extended washout to TP (90.9% [85.8-94.2%], p = 0.008) and to the washout confined to PVP (75.3% [68.2-81.2%], p < 0.0001). The specificities of the extended washout to TP (82.4% [56.5-94.4%]) and to HBP (82.4% [56.5-94.4%]) were lower than that of the washout confined to PVP (94.1% [67.6-99.2%]), but not significant statistically (p = 0.472).CONCLUSION: After excluding typical hemangiomas and lesions with a rim enhancement and targetoid appearance, the extension of washout appearance to TP

or HBP instead of restricting it to PVP allows a marked increase in sensitivity without a significant compromise in specificity.

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MC 02 AB-07 14:30 Per-lesion performance of adding recent dynamic enhanced liver CT to simulated abbreviated MRI for HCC diagnosis: Comparison with full-sequence gadoxetic acid-enhanced MRI in a multicenter settingSo Hyun Park1, Bohyun Kim2, Jimi Huh3, Seung Joon Choi1, Young Sup Shim1, Su-Joa Ahn1, Jei Hee Lee3, Hye Jin Kim2 1Gachon University Gil Medical Center, 2Ajou University Hospital, 3Ajou University School of Medicine, Korea. [email protected]

PURPOSE: To evaluate the diagnostic performance of adding recent dynamic enhanced CT to an abbreviated MRI (AMRI) in comparison to a full-sequence gadoxetic acid-enhanced MRI for hepatocellular carcinoma (HCC) diagnosis.MATERIALS AND METHODS: We retrospectively identified 109 consecutive treatment-naïve patients at high risk for HCC (estimated annual risk > 5%) who underwent dynamic liver CT and gadoxetic acid-enhanced MRI less than 3 months apart in two centers. Two readers reviewed two separate image sets: set 1 was dynamic liver CT added to AMRI comprising T2WI, DWI, and hepatobiliary phase image; set 2 was full-sequence gadoxetic acid-enhanced MRI. All observations > 5 mm and ≤ 30 mm were scored as presence or absence of major and ancillary features using the Liver Imaging Reporting and Data System (LI-RADS) v2017. The diagnostic performance of using LR-5 and ≥ LR-4 criteria in diagnosing HCC was described and compared by per-lesion sensitivity (sn), specificity (sp), positive predictive value (PPV), and diagnostic accuracy between image sets. Final diagnosis was based on the results of histopathologic examination in malignant nodules and image follow-up in benign nodules.RESULTS: Reference standard showed 87 HCCs in 81 patients (median, 21 mm; range, 8-30 mm). For set 1, the mean per-lesion sn, sp, and PPV were 95.4%, 69.7%, 89.3% for ≥ LR-4 and 64.4%, 93.9%, 96.6% for LR-5. For set 2, the mean per-lesion sn, sp, and PPV were 94.1%, 72.7%, 89.9% for ≥ LR-4 and 68.2%, 90.9%, 95.1% for LR-5. Diagnostic accuracy of set 1 (88.3%) was comparable to that of set 2 (88.1%) (95% CI lower limit difference, 0%). There was no significant difference in false-positive or false-negative diagnoses between two image sets (p = 0.667 and 0.703, respectively). Upon considering ancillary MR features in set 1, 13 more HCCs were upgraded to ≥ LR-4 from LR-3.CONCLUSION: Adding recent dynamic enhanced liver CT to AMRI showed comparable per-lesion sn, sp, PPV, and accuracy to a full-sequence gadoxetic acid-

enhanced MRI in HCC diagnosis. Recent dynamic enhanced liver CT may reduce the call back rate for dynamic enhanced MRI after an AMRI. AMRI is robust in characterizing indeterminate observations on dynamic enhanced liver CT.

MC 02 AB-08 14:40 Radiofrequency ablation versus cryoablation for perivascular hepatocellular carcinoma: Local tumor control and vascular complicationsSoyeon Cha, Tae Wook Kang Samsung Medical Center, Korea. [email protected]

PURPOSE: To compare cryoablation with radio-frequency ablation (RFA) in patients with perivascular HCC and to evaluate the local tumor control and vascular complications of both therapies.MATERIALS AND METHODS: The retrospective study was approved by the Institutional Review Board. The requirement for informed consent was waived. Between January 2015 and December 2017, 111 patients who underwent percutaneous cryoablation (n = 61) or FRA (n = 50) were enrolled. All patients had a single perivascular HCC (mean size, 1.3 cm) that were in contact with hepatic vessels (periportal or perivenous), ≥ 3 mm or larger in axial diameter. Cumulative local tumor progression (LTP) was evaluated. In addition, several procedure-related vascular complications were evaluated immediately after treatment and during follow-up images: peritumoral vessel thrombosis; transient hepatic ischemia or hepatic infarction; aggressive intrasegmental recurrence (AIR) (the simultaneous development of ≥ 3 nodular or infiltrative tumors).RESULTS: The median follow-up was 18 months. Both groups did not show significant differences in terms of baseline characteristics except the proportion of periportal tumor location (40.0% in the RFA group vs. 86.9% in the cryoablation group, p = 0.031). The cumulative LTP rates at 1 and 2 years were 5.7% and 22.1%, respectively, in the RFA groups, and 6.5% and 22.7%, respectively, in the cryoablation group, without significant difference (p = 0.918). However, peritumoral thrombosis (25% vs. 11.5%, p = 0.031) and transient hepatic ischemia or hepatic infarction (24% vs. 4.95%, p = 0.005) were more common in the RFA group than in the cryoablation group. Although there were not significant differences between two groups, AIR was only occurred in the RFA group (2% vs. 0%, p = 0.450).CONCLUSION: In patients with perivascular HCC, cryoablation is an effective treatment for local tumor control, comparable to RFA, with a low risk of vascular complications.CLINICAL RELEVANCE/APPLICATION: Although

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cryoablation has not been included as a standard care for HCC according to the recent Barcelona Clinic Liver Cancer guidelines, based on the our results, cryoablation may be a reasonable alternative for patients with limited liver function to avoid vascular complications.

MC 02 AB-09 14:50 Prediction of TACE refractoriness in patients with HCC using imaging features of gadoxetic acid-enhanced MRIJieun Byun1, So Yeon Kim1, Jin Hyoung Kim1, Seung Soo Lee1, Seong Ho Park2, Jae Ho Byun1,Moon-Gyu Lee3

1Asan Medical Center, 2Ulsan University College of Medicine, 3University of Ulsan-Asan Medical Center, Korea. [email protected]

PURPOSE: To investigate magnetic resonance imaging (MRI) features associated with transarterial chemoembolization (TACE) refractoriness in patients with HCC and to develop a prediction model.MATERIALS AND METHODS: Among 407 patients with intermediate-stage HCC (BCLC-B) who underwent TACE as a first-line treatment from January 2012 to December 2015, 181 patients having pre-procedural gadoxetic acid-enhanced MRI were included in this study. TACE refractoriness was determined according to the Japan Society of Hepatology guidelines. Univariate and multivariable analyses were performed to investigate the association between clinical factors including MRI features and the refractoriness. A prediction scoring model was constructed by a bootstrap resampling method. The performance of the prediction model was evaluated with respect to discrimination using with the area under the receiver operating characteristic curve (AUC).RESULTS: 55 pat ients (30.4%) showed TACE

refractoriness, while the remaining 126 (69.6%) showed good responses after TACE. Independent features associated with TACE refractoriness were alpha fetoprotein level, tumor number, maximum tumor size, atypical arterial enhancement pattern, arterial peritumoral enhancement, and presence of nonhypervascular hypointense nodule (NHHN) on hepatobiliary phase images. The prediction model derived from these variables showed good discrimination (AUC, 0.82, 95% CI, 0.75-0.89).CONCLUSION: The prediction model based on the MRI features can be used to estimate the risk of TACE refractoriness in patients with HCC.

MC 02 AB-10 15:00 - 15:20

New guidelines of hepatocellular carcinomas

So Yeon KimUniversity of Ulsan College of Medicine,

Asan Medical Center, [email protected]

MC 02 AB-11 15:20 - 15:40

Prediction of HCC invasiveness

Seong Hyun Kim Samsung Medical Center, Sungkyunkwan University

School of Medicine, Korea. [email protected]

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Liver: Single but not simple

Chairperson(s)Jeong Min Lee Seoul National University College of

Medicine, KoreaYong Yeon Jeong Chonnam National University

Hwasun Hospital, Korea

MC 02 AB-12 15:50 - 16:10 Update of cholangiocarcinoma and combined

hepatocellular cholangiocarcinoma

Hyungjin Rhee Yonsei University College of Medicine,

Severance Hospital, Korea. [email protected]

MC 02 AB-13 16:10 - 16:30

Updates of diffuse liver disease

Jeong Hee Yoon Seoul National University Hospital, Korea.

[email protected]

MC 02 AB-14 16:30 Arterial enhancement patterns on MR imaging as preoperative prognostic markers of intrahepatic mass-forming cholangiocarcinomaJi Hye Min1, Young Kon Kim2, Seo-Youn Choi3, Tae Wook Kang2, Soon Jin Lee2, Jeong Eun Lee1, Kyung Sook Shin1 1Chungnam National University Hospital, 2Samsung Medical Center, 3Soon Chun Hyang University College of Medicine, Korea. [email protected]

PURPOSE: To evaluate the prognostic factors of intrahepatic mass-forming cholangiocarcinoma (IMCC) and to determine the relationship between the magnetic resonance imaging (MRI) features of IMCC including arterial enhancement pattern, the clinicopathologic factors, and the clinical outcomes.MATERIALS AND METHODS: The Institutional Review Board approved this retrospective study. The need for informed patient consent was waived. This stud included 134 patients who underwent curative hepatic resection

and preoperative MRI for IMCCs (median size, 4.5 cm). The MRIs were reviewed for the IMCCs, which were classified according to the arterial enhancement pattern (diffuse hypoenhancement vs. peripheral rim enhancement vs. diffuse hyperenhancement). We performed survival analysis according to preoperative and postoperative clinicopathologic factors as well as imaging findings.RESULTS: In multivariate analysis, the CA 19-9 level (p = 0.010), tumor size (p = 0.001), tumor number (p = 0.008), tumor differentiation (p = 0.036), vascular invasion (p < 0.001), and arterial enhancement pattern (p < 0.001) were significant prognostic factors for overall survival (OS). The CA 19-9 level (p = 0.013), tumor size (p = 0.018), T classification (p = 0.013), necrosis (p = 0.019), and arterial enhancement pattern (p = 0.005) were significant prognostic factors for recurrence-free survival (RFS). There were significant differences in clinicopathologic features among the three arterial enhancement groups. The OS and RFS of the diffuse hyperenhancement group were significantly better than those of the peripheral rim or diffuse hypoenhancement group (p < 0.001).CONCLUSION: The arterial enhancement pattern on MRI, along with the CA 19-9 level and tumor size may be a useful prognostic marker in the preoperative evaluation of patients with IMCC.

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MC 02 AB-15 16:40 LR-M category in the Liver Imaging Reporting and Data System v2017: Diagnostic value of targetoid appearances on gadoxetic acid-enhanced MRIMinyoung Kim1, Ijin Joo1, Eun Sun Lee2, Jae Seok Bae1, Hwaseong Ryu3, Joon Koo Han4 1Seoul National University Hospital, 2Chung-Ang University Hospital, 3Pusan National University Yangsan Hospital, 4Seoul National University College of Medicine, Korea. [email protected]

PURPOSE: To evaluate the value of targetoid appearances for LR-M categorization (probably or definitely malignant, not HCC specific) in the Liver Imaging Reporting and Data System (LI-RADS) v2017 on gadoxetic acid-enhanced liver MRI (Gd-EOB-MRI) and to compare diagnostic performances of various targetoid appearances according to imaging sequences and dynamic phases.MATERIALS AND METHODS: This retrospective study included 110 patients at high-risk for HCC with pathologically-confirmed primary liver malignancies (55 patients with non-HCC malignancies including 23 intrahepatic cholangiocarcinomas (ICCs) and 32 combined hepatocellular cholangiocarcinoma (cHCC-CCA); and a tumor size-matched control of 55 HCCs) who had undergone Gd-EOB-MRI. For each observation, two independent radiologists assigned LI-RADS category, and assessed MR imaging features including targetoid appearances and major HCC features. Any discrepancies were resolved by a third reviewer. Frequencies of MR imaging features were compared between pathologic diagnoses and between LR-M and non-LR-M tumors.RESULTS: In all, 42.7% (47/110: 12 HCCs, 18 ICCs, and 17 cHCC-CCAs) and 57.3% (63/110: 43 HCCs, 5 ICCs, and 15 cHCC-CCAs) were assigned as LR-M and non-LR-M, respectively. Targetoid appearances including rim arterial phase hyper-enhancement (rim APHE), peripheral “washout”, delayed central enhancement, targetoid restriction, and targetoid transitional phase or hepatobiliary phase appearance were significantly more frequent in ICCs compared to cHCC-CCAs or HCCs (ps < 0.02). In LR-M tumors, in comparison to non-LR-M, all targetoid appearances were significantly more frequent (ps < 0.02), while major HCC features including APHE (not rim), “washout”, and enhancing “capsule” were significantly less frequent (ps < 0.01). For LR-M categorization, the most sensitive targetoid appearance was rim APHE (68.1%, 32/47), followed by delayed central enhancement (46.8%, 22/47) and targetoid restriction (34.0%, 16/47). In addition, all targetoid appearances showed high specificities (95.2%, 60/63~100%, 63/63) for LR-M categorization.

CONCLUSION: In the LI-RADS categorization of hepatic tumors on Gd-EOB-MRI, targetoid appearances which may lead to an LR-M assignment, among which the most sensitive would be rim APHE.

MC 02 AB-16 16:50 A meta-analysis of non-invasive diagnosis in non-alcoholic steatohepatitis by using MR imaging techniqueSeongwoo Kim1, Tae-Hoon Kim2, Youe Ree Kim1, Dong Min Kang1, Young Hwan Lee1, Kwon-Ha Yoon1 1Wonkwang University Hospital, 2Medical Convergence Research Center, Wonkwang University, Korea. [email protected]

PURPOSE: Accurate diagnosis in the hepat ic inflammation of NASH is significant and necessary for clinical management in conjunction with various MR imaging techniques. We performed a meta-analysis on MR studies for differentiating NASH from simple steatosis focusing on imaging markers.MATERIALS AND METHODS: A systematic literature search was performed in PubMed, EMBASE and Medline database from January 2000 to August 2017. Collecting and summarizing diagnostic tests applied by relevant literature, the revised tool for the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) was used to evaluate the quality of studies. For differential diagnosing the NASH from simple steatosis, pooled sensitivity, specificity, and summary receiver operating characteristics (SROC) curve were calculated to evaluate the MR diagnostic performances.

Fig. 1. Flowchart showing the process for the inclusion of studies. NAFLD: non-alcoholic fatty liver disease; NASH: non-alcoholic steatohepatitis

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RESULTS: Figure 1 showed flowchart showing the process for the inclusion of studies. Finally, 9 studies were included for NASH diagnostic accuracy, which was considered to be an efficient imaging biomarker in the diagnosis of NASH in present research (SROC, n = 9). For non-invasively diagnosing simple steatosis vs. NASH using MRI, the pooled sensitivity, specificity and AUC were 0.80 (95% CI, 0.45-0.94), 0.84 (95% CI, 0.48-0.98), and 0.88 (95% CI, 0.68-0.98), respectively.CONCLUSION: With the use of MR imaging technique, the sensitivity, specificity and AUC in distinguishing NASH from simple steatosis had a moderate diagnostic performance (> 0.8). To be an efficient biomarker in the non-invasive NASH diagnosis in clinical, it is still needed to improve the diagnostic performance supported by advances of various MR techniques.

MC 02 AB-17 17:00 Quantitative evaluation of liver fibrosis by T1 MR relaxometry compared with FibroscanByeong Hak Sim1, Suk Hee Heo2, Sang Soo Shin1, Yong Yeon Jeong2 1Chonnam National University Hospital, 2Chonnam National University Hwasun Hospital, Korea. [email protected]

PURPOSE: To determine whether T1 relaxation time of gadoxetic acid-enhanced liver MR imaging are able to detect and stage of hepatic fibrosis in patient with chronic liver disease.MATERIALS AND METHODS: 103 patients who suspected focal liver lesion underwent MR imaging and Fibroscan. The Fibroscan method was chosen as the gold standard to classify the hepatic fibrosis. Additional liver score was obtained with the APRI (AST to platelet index). To obtain T1 relaxation time, a transverse 3D VIBE sequence (TR = 3 ms, TE = 1.32 ms) on 3T MRI was used. T1 relaxation times were acquired prior to and 20 minutes after gadoxetic acid administration. The reduction rate of the T1 relaxation time (rrT1) between the pre- and post-contrast images were calculated, and the optimal cutoff values for the fibrosis staging were determined with receiver operating characteristic (ROC) curve analyses.RESULTS: Pre- and post T1 relaxation times showed a constant increase with the severity of liver fibrosis. rrT1 showed a tendency of constant decrease with the severity of liver fibrosis. There was statistically significant differences between F2 and F3 in pre-T1 relaxation time and between F3 and F4 in post-T1 relaxation time and rrT1. ROC analysis revealed that combined use of pre T1 relaxation time and rrT1 could useful for differentiation of different fibrosis stages except mild fibrosis.

CONCLUSION: Combined use of pre T1 relaxation time and rrT1 in liver MR imaging could be a useful diagnostic method for liver fibrosis staging.

MC 02 AB-18 17:10 Role of MRI in the monitoring of patients of NAFLD: Comparison with US, lipid profile and body mass indexNikhil Makhija, Madhusudhan Seetharama, Deep Srivastava, Raju Sharma, Shivanand Gamanagatti, Naval Vikram, Gurdeep Kaur All India Institute of Medical Sciences, India. [email protected]

PURPOSE: To study the role of magnetic resonance imaging (MRI) in diagnosis and monitoring hepatic fat content in cases of Non Alcoholic Fatty Liver Disease (NAFLD).MATERIALS AND METHODS: Forty one adult treat-ment-naive patients (mean age, 39 years; M:F = 22:19) of suspected NAFLD who showed fatty liver on screening ultrasonography (US) were included in this prospective study after obtaining approval from Institutional Ethics Committee. Known diabetics, alcohol users (> 20 g/day) and patients on chronic drug intake were excluded. Their baseline clinical (weight, BMI) and biochemical (LFT, lipid profile, blood sugar) parameters were obtained. US and MRI were done for all patients and mean fat fraction was obtained. Patients were advised dietary and lifestyle changes and oral Vitamin E for six months, after which, repeat clinico-biochemical tests, US and MRI were done using the same protocol and compared with pre-treatment findings. Based on compliance, they were categorized in two groups, good compliance and poor compliance.RESULTS: 30 had good compliance and 11 had poor compliance to intervention. There was no significant difference between the two groups in the clinical as well as biochemical parameters. Mean fat fraction and mean stiffness value also had no statistically significant difference. Those who had good compliance, there was significant reduction in BMI (p < 0.001), serum triglycerides, total cholesterol and liver fat content (p < 0.05). In poor compliance, there was significant increase in BMI (p < 0.001), reduction in HDL (p < 0.05) and no significant change in the rest of the parameters including total cholesterol, LDL and triglycerides. Liver fat fraction demonstrated increase in mean liver fat fraction, (p < 0.05). In cases with change in mean liver fat content of about ~4.4%, USG did not show change in grade and mean change in liver fat content ~9.5% was required for US to pick up. There was linear correlation (r = 0.96, p < 0.001) between hepatic fat content values obtained from in-phase-opposed phase and spectroscopy.

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CONCLUSION: MRI is useful not only to accurately quantify but also in monitoring hepatic fat content as clinico-biochemical parameters cannot reliably predict the presence and extent of fatty liver. US is not able to pick up small changes in hepatic fat content.

MC 02 AB-19 17:20 Grading of hepatic fibrosis using iodine map of spectral liver CTJeong Hee Yoon1, Jeong Min Lee2, Joon Koo Han2

1Seoul National University Hospital, 2Seoul National University College of Medicine, Korea. [email protected]

PURPOSE: To determine whether iodine map from spectral computed tomography (CT) is able to provide hepatic extracellular volume fractions (fECVs) for grading hepatic fibrosis (HF).MATERIALS AND METHODS: A total of 57 patients (M:F = 42:15; mean age, 54.3 ± 11.9 years) histologically diagnosed with HF underwent quadriphasic liver CT at the scanner with spectral detector (IQon, Philips Healthcare) at 120 kVp. Delayed phase was obtained 3 minutes after standard dose of contrast media administration. On the generated iodine maps of iodine, approximately 0.8-1 cm2 round regions of interest (ROIs) were drawn avoiding focal lesion and vessels in the liver, and aorta for calculating fECV as follows: fECV (%) = Iodine concentration liver (mg/ml)/ Iodine concentration aorta (mg/ml) × (100-Hematocrit [%]). Correlation between fECV and HF stage was evaluated using Spearman’s correlation coefficient. fECVs, iodine concentration and effective Z were compared between F0-1 (n = 7), F2-3 (n = 17) and F4 (n = 33), and between F0-3 and cirrhosis (F4).RESULTS: fECVs showed a moderate correlation with pathologic HF staging (r = 0.55, p < 0.0001). fECV was higher in F4 than F2-3 (36.0 ± 8.0% vs. 26.4 ± 4.1, p < 0.01) but there was no significant difference between F2-3 and F0-1 (28.8 ± 3.7%, p > 0.05). In comparison between F0-3 and F4, F4 showed significantly higher

fECV than F0-3 (36.0 ± 8.0% vs. 27.7 ± 4.2%, p < 0.0001). In addition, iodine density of the liver (mg/ml) was significantly higher in F4 than F0-3 (1.87 ± 0.28 vs. 1.63 ± 0.33, p = 0.006). Effective Z was also higher in F4 than F0-3 (8.42 ± 0.16 vs. 8.31 ± 0.20, p = 0.026), but there was a substantial overlap of the values.CONCLUSION: Iodine map of delayed phase from the spectral CT enables to estimate fECV and fECV increased as HF progressed and F4 showed significantly higher fECV than F0-3.

MC 02 AB-20 17:30 US attenuation imaging for noninvasive evaluation of hepatic steatosis: Evaluation of reproducibility and correlation with visual assessment resultsJeongin Yoo1, Jeong Min Lee2


PURPOSE: To evaluate the reproducibility of ultrasound (US) attenuation imaging (ATI) for noninvasive evaluation of hepatic steatosis in patients with suspected nonalcoholic fatty liver disease (NAFLD) or abnormal results on liver function test (LFT) and to determine the correlation between ATI and visual assessment of hepatic steatosis.MATERIALS AND METHODS: This prospective study was approved by the Institutional Review Board, and informed consent was obtained from all patients. One board-certified abdominal radiologist performed conventional gray-scale US examination and two sessions of ATI measurements by using Aplio i900 (Canon Medical System) in 143 consecutive patients with suspected hepatic steatosis or abnormal LFT. ATI measurement consisted of two sets in which the radiologists performed at least 6 times of measurements each. ATI values in each set were averaged, and reproducibility of ATI exams were assessed using intraclass correlation (ICC). Two radiologists retrospectively reviewed gray-scale images and independently assessed the degree of hepatic steatosis on a four-point scale: 0 (absent), 1 (mild), 2 (moderate), and 3 (severe). The mean ATI values were correlated with the qualitative assessment results using a Spearman’s rank correlation.RESULTS: For reproducibility of ATI, ICC coefficient was 0.895 (95% confidence interval [CI]: 0.853-0.924) which can be regarded as “good” to “excellent” reliability and a coefficient of variation of 7.12% (standard deviation = 0.051). Spearman’s rank correlation showed significant correlation between ATI and visual assessment by both reviewer 1 (p < 0.0001, r = 0.717) and reviewer 2 (p < 0.0001; r = 0.605). Weighted k analysis revealed

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good agreement (linear weights, k = 0.736; standard error = 0.047; 95% CI: 0.644-0.827) between the visual assessments made by the two reviewers.CONCLUSION: ATI demonstrates good to excellent reproducibility and significantly correlated with visual assessment of hepatic steatosis in patients with suspected NAFLD or abnormal LFT.

MC 02 AB-21 17:40 Evaluation with attenuation imaging on US for the diagnosis of fatty liver disease: Preliminary studyYoue Ree Kim, Young Hwan Lee, Dong Min Kang, Kwon-Ha Yoon Wonkwang University Hospital, Korea. [email protected]

PURPOSE: To correlate ultrasound (US) attenuation coefficient with the degree of fatty liver disease and to analyze the relationship among US attenuation coefficient, hepatic attenuation using computed tomography (CT) and CT liver to spleen ratio.MATERIALS AND METHODS: From April 2018 to May 2018, 23 patients with fatty liver disease and 9 patients without fatty liver disease (normal controls, group I) who underwent US examination using newly released application, attenuation imaging (Aplio i800, Canon Medical Systems Corporation) were enrolled. 23 fatty liver disease patients were divided into three groups; mild (group II, n = 8), moderate (group III, n = 7), severe (group IV, n = 8) using gray scale imaging feature. Quantitative measurements of attenuation coefficient were measured. CT hepatic attenuation and L/S ratio were analyzed in 15 patients who had CT images within 1 month. Serum markers including AST and ALT were collected. Attenuation coefficient were compared by ANOVA test among each groups. Relationship among attenuation coefficient, CT attenuation and LS ratio were analyzed by Pearson correlation.RESULTS: The mean values of AST and ALT levels were 32.2 and 33 in group I and 48.1 and 46.8 in group II-IV (p = 0.101, p = 0.133). The mean attenuation coefficient of group I and group II-IV was 0.563 and 0.765 (p < 0.000). The mean attenuation coefficient of group I, II, III and IV were 0.563 ± 0.050, 0.664 ± 0.0575, 0.735 ± 0.115 and 0.848 ± 0.118 (p < 0.000). Attenuation coefficients demonstrated strong negative correlation with hepatic attenuation (r = -0.817, p = 0.01) and with LS ratio (r = -0.838, p = 0.01).CONCLUSION: The attenuation coefficient using US showed discriminative values of the severity of fatty liver disease, and demonstrated strong negative correlation with hepatic attenuation and LS ratio.


Stomach and small bowel imaging

Chairperson(s)Jong Young Oh Dong-A University, College of

Medicine, KoreaKyung Sook Shin Chungnam National University

Hospital, Korea

SS 16 AB-01 08:00 Stratification of postsurgical CT surveillance based on extragastric recurrence of early gastric cancerNieun Seo, Joonseok Lim, Kyunghwa Han, Yong Eun Chung, Myeong-Jin Kim Severance Hospital, [email protected]

PURPOSE: The major role of postsurgical computed tomography (CT) in early gastric cancer (EGC) is to detect extragastric recurrence. We aimed to develop a risk-scoring system to predict extragastric recurrence and stratify the postsurgical CT surveillance based on the risk of extragastric recurrence of EGC.MATERIALS AND METHODS: Data from 3162 patients who underwent curative surgical resection for EGC were reviewed to develop a risk-scoring system to predict extragastric recurrence. Risk scores were based on the predictive factors for extragastric recurrence, which were determined using Cox proportional hazard regression model; their performance was internally validated using bootstrapping. External validation was performed using an independent data set (n = 430) to evaluate the predictive accuracy of the risk-scoring system.RESULTS: The overall incidence of extragastric recurrence was 1.4% (44/3162). Five risk factors (lymph node metastasis, indications for endoscopic resection, male sex, positive lymphovascular invasion, and elevated macroscopic type) were significantly associated with extragastric recurrence. These factors were incorporated into the risk-scoring system and weighted with scores ranging from 1 to 10. Then, the patients were categorized into four risk groups based on the risk scores. The 10-year extragastric recurrence-free survival differed significantly among these groups (100%, 99.9%, 99.3%, and 96.5%; p < 0.001). The predictive accuracy of the risk-scoring system in the development cohort was 0.864 (Harrell’s C-index; 95% confidence interval, 0.613-1.000). Discrimination was good after internal (0.852, 0.801-0.910) and external validation (0.705, 0.521-0.931).CONCLUSION: This risk-scoring system might be useful to predict extragastric recurrence and stratify the

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CT surveillance protocol of EGC after curative surgical resection.

SS 16 AB-02 08:10 Diagnostic accuracy of dual-energy CT-based nomogram to predict lymph node metastasis in gastric cancerJing Li1, Mengjie Fang2, Rui Wang3, Jianbo Gao3 1The Affiliated Cancer Hospital of Zhengzhou University, 2University of Chinese Academy of Sciences, 3The First Affiliated Hospital of Zhengzhou University, China. [email protected]

PURPOSE: To develop and validate a dual-energy CT based nomogram for the preoperative prediction of lymph node metastasis (LNM) in patients with gastric cancer (GC).MATERIALS AND METHODS: A total of 210 surgical confirmed GC patients (M:F = 159:51; mean age, 59.8 ± 7.7 years; range, 28-79 years) who underwent spectral CT scans were retrospectively enrolled and split into a primary cohort (n = 140) and validation cohort (n = 70). Clinical information and follow up data including overall survival (OS) and progression free survival (PFS) were collected. The iodine concentration (IC) of the primary tumors at the arterial phase (AP) and venous phase (VP) were measured and then normalized to aorta (nICs). Univariate analysis, multivariable logistic regression analysis and Cox regression analysis were performed to screen predictive indicators for LNM and outcome. A nomogram for risk factors of LNM was developed and its performance was measured using ROC, accuracy and Harrell’s concordance index (C-index).RESULTS: Tumor thickness, Borrmann classification and ICVP were independent predictors for LNM. The nomogram was significantly associated with LN status (p < 0.001). The AUCs for predicting LNM were 0.760 (95% confidence interval [95% CI], 0.680-0.840) in primary cohort and 0.793 (95% CI, 0.678-0.908) in validation cohort. The nomogram also exhibited a prognostic ability with C-indices of 0.675 (95% CI, 0.571-0.779; p < 0.001) for PFS and 0.643 (95% CI, 0.518-0.768; p = 0.025) for OS.CONCLUSION: This study presented a dual-energy quantification based nomogram, which can be used to facilitate the preoperative individualized prediction of LNM in patients with GC.

SS 16 AB-03 08:20 Can perfusion CT differentiate GIST from other benign subepithelial tumors in the stomach?Seungchul Han, Se Hyung Kim, Dong Ho Lee, Joon Koo Han Seoul National University Hospital, Korea. [email protected]

PURPOSE: To evaluate the diagnostic performance of per fus ion CT parameters in d i f ferent ia t ing gastrointestinal stromal tumors (GISTs) from other benign subepithelial tumors (SETs) in the stomach.MATERIALS AND METHODS: Twenty-eight patients with surgically proven gastric subepithelial tumors underwent perfusion CT using a MDCT scanner at 80 kVp. Two radiologists then analyzed key CT features including homogeneity and degree of enhancement in consensus. Perfusion CT parameters such as blood flow, blood volume, mean transit time, and permeability surface value were also calculated. Thereafter, comparative analysis of their CT features and perfusion CT parameters was performed between GISTs and other benign SETs using the Chi-square test, Fisher’s exact test, or Mann-Whitney U test. Diagnostic performances of the perfusion CT parameters were also evaluated using receiver operating characteristic (ROC) analysis.

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RESULTS: On histologic examination, 22 patients were proven to have GISTs (4, no risk of malignancy; 9, very low risk; 2, low risk; 5, intermediate risk; and 2, high risk) while the other 6 patients had 3 leiomyomas, 2 schwannomas, and 1 totally necrotic nodule. On univariate analysis, no CT features demonstrated a significant difference between GISTs and non-GISTs (p > 0.05). However, the mean permeability surface (PS) value in the strongest enhancing area of GISTs (27.7 ± 25.7 ml/100 g/min) was demonstrated to be significantly higher than that of other SETs (7.3 ± 8.7 ml/100 g/min) (p = 0.017). On ROC analysis, an area under the curve of 0.818, sensitivity of 90.9% (20/22), and specificity of 66.7% (4/6) were achieved when the cut-off for the PS value was set at 7.17 ml/100 g/min (p = 0.019).CONCLUSION: Perfusion parameters obtained from perfusion CT were demonstrated to be helpful in the differentiation of GISTs from other benign SETs as PS values in GISTs were significantly higher than in non-GISTs.

SS 16 AB-04 08:30 PET/CT-based radiomics signature for the preoperative prediction of vascular invasion in gastric cancerLijing FanThe Affiliated Cancer Hospital of Zhengzhou University, [email protected]

PURPOSE: To develop and validate PET/CT?based radiomics signature for the preoperative prediction of vascular invasion in gastric cancer.MATERIALS AND METHODS: A total of 93 surgical confirmed GC patients (M:F = 65:28; mean age, 57.32 ± 12.13 years; range, 24-83 years) who underwent PET-CT scans were retrospectively enrolled and split into a primary cohort (n = 60) and validation cohort (n = 33). Radiomics features were extracted from the CT and PT images of each patient. A radiomics signature was then constructed with the least absolute shrinkage and selection operator algorithm in the training set. Nomogram performance was assessed in the training set and validated in the validation set. Finally, receiver operator characteristics (ROC) analysis was performed with the combined training and validation set to estimate the clinical usefulness of the nomogram. A nomogram for risk factors of vascular invasion which incorporated clinical factors, SUVmax, histological grade radiomics signature and was developed and its performance was measured using sensitivity and specificity.RESULTS: A total of 36 radiomics features showed significant differences between different vascular invasion status. A radiomics signature was constructed

based on three features, including two wavelet-based features and one LBP-based feature. The model showed good discrimination both in primary cohort and validation cohort, with AUC of 0.776 (95% CI, 0.693-0.859) and 0.769 (95% CI, 0.689-0.851). The sensitivity and specificity of radiomics signature in the training set were 0.750 and 0.778 respectively to predict vascular invasion in gastric cancer.CONCLUSION: The presented PET-CT based shows favorable predictive accuracy for in patients with gastric cancer.

SS 16 AB-05 08:40 Approaching bowel masses: Integrating imaging findings on CT with histopathologyAnkit Balani1, Chinky Chatur2, Umamahesh M2, Rajani S. Sunnadkal2 1Vijaya Diagnostic Centre, Hyderabad, 2Yashoda Hospital, Hyderabad, India. [email protected]

PURPOSE: To study the advantage of CT in detection, localization and characterization (extent of involvement, invasion of adjacent structures and local and distant metastasis) of bowel masses.MATERIALS AND METHODS: Hospi ta l -based prospective study conducted between June 2015 to May 2017. Inclusion criteria included patients with complaints of melena, constipation, diarrhea, alternate diarrhea and constipation, weight loss, anorexia; patients with bowel lesion detected on CT and patients who underwent histopathological examination for bowel mass lesion. A total of 75 patients fulfilled the inclusion criteria. The observations and results of the study were tabulated under the headings of age group, gender, clinical presentation, site of involvement, type of involvement (circumferential lesion/mass lesion), enhancement pattern (homogeneous/heterogeneous/none), lymph nodal involvement, distant metastases, ascites,

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involvement of adjacent structures and complications like fistula, intestinal obstruction or intussusception if any. The results of the study were correlated with histopathological findings to assess the role of CT in detection, localization and characterization of bowel masses.RESULTS: Age group ranged from 8-89 years with most common age group being 50-69 years. Males (43/75-57.33%) were found to be more affected than females (32/75-42.66%). Out of the 75 lesions, 56 presented as circumferential lesions and 19 as mass lesions. Predominant imaging findings of adenocarcinoma were irregular, asymmetric wall thickening causing luminal narrowing with tendency for obstruction, short-segment involvement with an abrupt transition from unaffected bowel wall to mass (shouldering), locoregional lymph node (LN) enlargement. Primary bowel lymphoma, carcinoid, GIST, lipoma and others presented with varying typical imaging findings. Of the 75 patients, CT correctly identified 67 cases in correlation with histopathology while in 8 cases CT diagnosis did not correlate with histopathological diagnosis. The test of agreement showed that imaging findings on CT had almost perfect agreement with histopathological findings with Cohen’s Kappa coefficient of 0.891.CONCLUSION: CT has a fundamental diagnostic value in the evaluation of bowel neoplasms, both in characterizing the lesions and in assessing their loco-regional and distant spread.

SS 16 AB-06 08:50 Routine addition of anal scan to MR enterography in Crohn’s patients: Clinical value assessed in an Asian cohortPyeong Hwa Kim1, Seong Ho Park2, Byong Duk Ye1, Jong Seok Lee1, Hyun Jin Kim1, Ah Young Kim1

1Asan Medical Center, 2University of Ulsan College of Medicine, Korea. [email protected]

PURPOSE: Anal MR scan can be facilely added to MR enterography (MRE) in a single sitting. Routine addition of anal scan to MRE might potentially provide some benefits particularly in Asian patients with Crohn’s disease (CD) as they have a higher rate of fistula in ano (FIA) compared to Western patients. This study was to evaluate the diagnostic yield and clinical impact of such routine anal MR scan in CD patients undergoing MRE unsuspected of FIA.MATERIALS AND METHODS: An anal MR scan (T2 with and without fat suppression, contrast-enhanced fat-suppressed T1, and diffusion-weighted using b factor of 900 s/mm2 sequences) was added to 788 consecutive MRE examinations performed in 636 CD patients between June 2012 and December 2017. The initial examination in each patient was included in this study. Of the 636, 172 patients who were symptomatic (i.e., with symptoms or signs of FIA or being followed for known unhealed FIA) were excluded. Anal MR scans of the remaining 464 patients (mean age ± SD, 29.8 ± 9.2 years; M:F = 364:100) unsuspected of FIA were finally analyzed. Images were reviewed regarding the presence/absence of incidental tracts or abscesses and the morphology and types according to Parks’ classification of the tracts if present. In patients who showed tracts or abscesses, their clinical follow-up records were reviewed to determine the clinical outcome of the incidental abnormalities.RESULTS: Fifty five (12%) of 464 patients revealed incidental tracts (i.e., no skin opening) on MR: intersphincteric in 38 (69%), superficial in 6 (11%), extrasphincteric in 5 (9%), transsphincteric in 2 (4%), and combined in 4 (7%). Seven patients (13%) had branching tracts. None had abscesses. In 44 patients (80%), linear T2-dark signal palisading the tract was shown at least in some areas along the tract. During the median follow-up of 20 months (range, 1-69 months) after the incidental MR detection, six patients (11%) required surgical therapy at 1-36 months.CONCLUSION: The diagnostic yield of routine anal MR scan in our Asian CD patients unsuspected of FIA was not high (12%), and the incidental tracts rarely required surgery (11%). Therefore, the routine addition of anal scan does not seem adequate, and referral by a suspicion of FIA raised by careful prior clinical

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examination would be more appropriate.

SS 16 AB-07 09:00 Evaluation of image findings on CT enterography for endoscopic complete remission after anti-tumor necrosis factor-alpha therapy in patients with Crohn’s diseaseJieun Kim, Seung Ho Kim, Tae Oh Kim, Jung-Hee Yoon Inje University Haeundae Paik Hospital, Korea. [email protected]

PURPOSE: To evaluate the image findings of CT enterography (CTE) obtained in patients with endoscopic complete remission (CR) after anti-tumor necrosis factor (TNF)-alpha therapy for Crohn’s disease.MATERIALS AND METHODS: Between August 2010 and October 2017, 36 consecutive patients with Crohn’s disease who received anti-TNF-alpha therapy and underwent pre-and post-therapy CTE as well as ileocolonoscopy were initially enrolled. CTE was performed with standard-dose enteric phase scan. Eleven patients were excluded due to a mismatch of follow-up intervals or a long interval (over two weeks) between CTE and ileocolonoscopy. Therefore, 25 patients (M:F = 16:9; mean age, 26 years; range, 18-43 years) were finally analyzed. Two blinded readers reviewed pre-and post-therapy CTE image findings in consensus as for active inflammation, i.e., mural hyperenhancement, mural thickening (thickness > 3 mm), mural stratification, and increased pericolonic fat attenuation in the rectum, colon, and terminal ileum, respectively. The endoscopic CR indicated mucosal healing identified by ileocolonoscopy and served as the reference standard.RESULTS: Eleven patients had endoscopic CR. Six patients of them (6/11, 55%) had residual mild mural thickening and mild mural hyperenhancement on post-therapy CTE compared to pre-therapy CTE. The other 5 patients did not have any post-therapy CTE abnormalities. Non-endoscopic CR group (4 partial remissions and 10 poor remissions) showed a higher concordance rate of 86% (12/14) with post-therapy CTE than endoscopic CR group did (45%, p = 0.0358).CONCLUSION: Residual mild mural thickening and mild mural hyperenhancement were seen on post-therapy CTE over half of the patients having endoscopic CR after anti-TNF-alpha therapy for Crohn’s disease.


Bowel imaging: Diagnosis and techniques

Chairperson(s)Kwon-Ha Yoon Wonkwang University College of

Medicine, Korea Kyoung Ho Lee Seoul National University Bundang

Hospital, Korea

SS 18 AB-01 09:50 Role of color Doppler imaging in borderline size appendix-simple method to improve specificity for appendicitisNaveen Kumar1, Eshita Agrawal2 1SSIMS & RC, Davangere, 2MBBS, India. [email protected]

PURPOSE: To differentiate between the normal appendix from inflamed appendix on color Doppler imaging. Continuous intramural vascular signal measuring at least 3 mm on color Doppler imaging is highly specific for appendicitis in borderline-size appendix.MATERIALS AND METHODS: All patients were scanned with a single ultrasound machine and 9-15 MHz transducers (GE Healthcare).STUDY DESIGN: Prospective studySAMPLE SIZE: 50 patients referred to radiology dept with possible appendicitis from 2015 to 2017.SOURCE OF THE DATA: Patients coming to the department of radio diagnosis at SSIMS & RC Davangere with a clinical history of pain and tenderness in RIF and all patients who had undergone graded-compression sonography for possible appendicitis and whose appendices were of diagnostically borderline size (6-8 mm maximum outer diameter).RESULTS: Of the 50 patients, 17 had type 1 flow (of whom 3 had appendicitis); 13 had type 2 flow (of whom 11 had appendicitis); and 20 had absent flow (of whom 5 had appendicitis).CONCLUSION: Graded-compression US remains our first-line method in the evaluation of patients referred with clinically suspected acute appendicitis. Type II flow (continuous linear or curvilinear flow > 3 mm) within the wall of the appendix is highly specific, yet insensitive, for appendicitis in borderline sized appendix. Type I flow (punctuate dispersed signal) is neither sensitive nor specific for appendicitis and can be seen normal appendix.

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SS 18 AB-02 10:00 Application of US and Alvarado score in the diagnosis of appendicitisChuluunbaatar Otgonbaatar, Khandsuren Baasansharaw, Tuvshinjargal Dashjamts, Tugsjargal Purevsukh Mongolian National University of Medical Sciences, Mongolia. [email protected]

PURPOSE: Acute appendicitis is the one of the most common acute conditions requiring urgent abdominal surgery. It has been observed that many patients undergoing appendectomy prove to be negative on histopathology of the surgically removed appendix, which is the gold standard for diagnosis of appendicitis.MATERIALS AND METHODS: This was a descriptive study, conducted at the department of general surgery and department of radiology, the first general hospital from January to December 2016. A total of 98 cases were identified and the clinical, radiological, surgical and histopathological data were reviewed. Patients were clinically assessed for Alvarado score. Sonographic findings were retrospectively classified as: positive, negative and nonvisualized appendix.RESULTS: The age of the patients ranged from 16-74 years with a mean age of 28.90 ± 10.9. The degree of appendicitis was 15 catarrheal, 66 phlegmenous and 17 gangrenous which is shown as follows. The negative appendectomy rate was 15.3%. In patients having in the score of 7-10; 3 patients had catarrheal appendicitis, while in the score less than 5; 5 patients had catarrheal appendicitis. The sensitivity and specificity of Alvarado score for diagnosing appendicitis was 56.6% and 80.0%. In 80 out of 98 ultrasonography (US) cases, the scan showed direct sign of appendicular inflammation, namely wall thickness > 3 mm 8.75%, diameter > 6 mm 100% and appendicolith 3.75%; in the remainder indirect signs as increased echogenicity of local mesenteric fat 22.5% sign of secondary small bowel obstruction 12.50% or free fluid 18.75% were present. Using cut-off diameters to define 3 categories (diameter < 5 mm, 6-8 mm, > 8 mm), catarrhal appendicitis was present in these categories 20%, 91.9% and 95.8%. Appendix was visualized in 67 of the 80 enrolled patients. US positive presented 62.2% while negative appendices were 19.4%. US positive 4 and negative 5 cases were showed negative appendectomy out of those visualized appendices. Histologically 11 phlegmonous and gangrenous appendicitis were presented in the 13 cases that didn’t not show any sign by US. The sensitivity and specificity of US for diagnosing appendicitis was 82% and 63.6%.CONCLUSION: All the patients with suspected appendicitis should be provided by standardized US

protocol to improve sensitivity and specificity.

SS 18 AB-03 10:10 A study of diagnostic value of diffusion-weighted MR imaging in diagnosis of acute appendicular pathologiesKishan Ashok Bhagwat, Vinay Dev SSIMS & RC, Davangere, India. [email protected]

PURPOSE: To evaluate the role of diffusion weighted magnetic resonance imaging (MRI) in diagnosing the cases of acute appendicular pathologies. To correlate the MR imaging findings with ultrasonography (US)/histo-pathological examination wherever applicable.MATERIALS AND METHODS: Data for the study of 40 cases was collected from the patients referred to the department of radio-diagnosis at SSIMS & RC, Davangere with history of right iliac fossa pain, suspicious of acute appendicular pathologies. Two radiology residents evaluated each case separately by US and MRI examinations independently and recorded the imaging features. The imaging features and final diagnosis were documented in a structured case record form, separately. An experienced radiologist reviewed those cases based on clinical information and imaging findings (both US and MRI). Histo-pathological examination was carried out for the surgically managed cases. Using GE 1.5T MRI, DWI for the abdomen was performed using B (500) value where inflamed appendix showed restriction on DWI and ROI was set in the right iliac fossa and then ADC was done for the B value.INCLUSION CRITERIA: Patients with history of right iliac fossa pain suspicious of acute appendicitis.Patients of all age groups will be included in the study.Patients with history of pain abdomen of > 48 hours duration with clinical symptoms and signs suggestive of appendicular mass or appendicular abscess.EXCLUSION CRITERIA: Patients with implants, cardiac pacemakers, cochlear implants.Patients who are claustrophobic/unwilling for imagingRESULTS: In our review of 40 cases with diagnosis of acute appendicitis, all cases showed ADC value more than 1 × 10-3 mm2/sec (mean ADC value, 1.8 × 10-3 mm2/sec). Out of 40 cases, 37 cases were positive for acute appendicitis. Out of that, 10 cases were managed surgically and the remainder 27 cases conservatively. 5 cases are proven with histopathological examination. Out of 37 cases, 21 cases were acute appendicitis without peri-appendicular inflammation, 5 cases were acute appendicitis with minimal peri-appendicular inflammatory fat stranding, 9 cases with acute appendicitis and free fluid in the right iliac fossa, 1 case with appendicolith and 1 with appendicular Phlegmon.

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Fig. a. Axial DW MR image of a male patient, showing the inflamed appendix.b. Axial DWI MR image showing the appendicular Phlegmon, in a female patient.CONCLUSION: In our study we found DWI MRI with ADC values can help in the diagnosis of acute appendicular pathologies and can be preferred as a non-invasive non-radiation method for patients with acute appendicular pathologies.

SS 18 AB-04 10:20 Complicated sigmoid volvulus: Identification of the high risk patients necessitating emergent surgerySubin Heo, Hye Jin Kim Ajou University Hospital, Korea. [email protected]

PURPOSE: To determine which clinical, laboratory, or computed tomography (CT) findings can help to accurately identify complicated sigmoid volvulus requiring surgery instead of endoscopic detorsion in the emergency setting.MATERIALS AND METHODS: We performed a retrospective study of data from cohort of 51 patients admitted for sigmoid volvulus in the emergency department from January 2003 to July 2017. These patients attempted initial endoscopic detorsion after CT. Contrast-enhanced CT findings were retrospectively reviewed by two radiologists in consensus. Clinical and laboratory findings were also analyzed to evaluate the complicated sigmoid volvulus defined as irreversible bowel ischemia to necrosis requiring surgery. The reference standard for complicated sigmoid volvulus was based on surgery and follow-up endoscopic findings. Patients were categorized with complicated and simple sigmoid volvulus group. The characteristics of the two groups were compared using chi-square or Fisher exact tests. Univariate and multivariate analyses were performed to identify the risk factors predicting the complicated sigmoid volvulus.RESULTS: Of 51 study patients, 11 patients (21.6%) were found to have complicated sigmoid volvulus, whereas 40 patients (78.4%) had simple sigmoid volvulus. Univariate analysis revealed three CT findings of reduced bowel wall enhancement, increased bowel wall thickness (> 2.2 mm), and mesenteric

vein thrombosis, as well as two laboratory findings of elevated C-reactive protein and lactate levels were significantly associated with complicated sigmoid volvulus. In multivariate analysis, two CT findings of reduced bowel wall enhancement (HR, 20.2; 95% CI: 1.8, 220.4) and increased bowel wall thickness (HR, 11.9: 95% CI: 2.5, 57.8) and one clinical finding of low systolic blood pressure (< 90 mmHg [HR, 66.8, CI: 4.5, 984.3]) were identified as independent predictive factors of complicated sigmoid volvulus.CONCLUSION: CT findings of reduced bowel wall enhancement and increased bowel wall thickness together with low systolic blood pressure can predict the complicated sigmoid volvulus necessitating surgery instead of colonoscopic detorsion as a primary emergency treatment of choice.

SS 18 AB-05 10:30 Ischemic bowel disease: Radiologist’s perspectiveAnoop Madayambath Karivellur Baby Memorial Hospital, India. [email protected]

PURPOSE: Ischemic bowel disease (mesenteric ischemia) is a life-threatening condition. Categorized into different types (Flowchart 01), this entity requires early recognition, so that warning signal is sent to physician for prompt and aggressive management. MATERIALS AND METHODS: Majority of bowel is supplied by celiac, superior mesenteric (SMA) and inferior mesenteric arteries. The presence of extensive collateral network makes the occurrence of acute mesenteric ischemia (AMI) increasingly rare. Embolism is the most common cause of AMI apart from, aortic dissection, vasculitis, abdominal inflammations. Portal hypertension and thrombophilias cause venous occlusion. Non-occlusive mesenteric ischemia (NOMI) occurs due to cardiac or renal disease, septicemia or drug toxicity. Dynamic CT angiography is the investigation of choice (94% sensitivity and 96% specificity). Elevated peak systolic velocity > 200 cm/s and > 275 cm/s in celiac and SMA respectively on Doppler US, point towards critical stenosis in chronic mesenteric ischemia (CMI). In patients with contrast allergy and deranged renal function, MR angiography can be used.RESULTS: Imaging features depends on the underlying cause, duration and site of occlusion. Demonstration of thrombus within vessel lumen, attenuated caliber, abrupt cut off , pseudo-aneurysms, vessel wall thickening are major findings. Bowel wall changes can occur in the form of increased attenuation, bowel wall thickening/thinning, hypo or hyper enhancement of bowel wall. Presence or absence of hazy mesentery

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and ascites favor one entity over the other. Evidence of infarction in other organs, pneumatosis intestinalis, portal venous gas, pneumoperitoneum may be seen in advanced cases. Differentiating features in types of AMI and flow-chart for management in mesenteric ischemia is provided in Table 01 and Flowchart 02/03. Catheter angiography with mechanical/pharmacological thrombolysis in AMI and balloon angioplasty/stenting in CMI are increasingly being used. In the current scenario, endovascular intervention can act as a bridge therapy so that patients improve their general condition to attain fitness for definitive surgical bypass procedure.CONCLUSION: In the current scenario, patients with acute severe abdominal pain, and abdominal US reveal no solid organ abnormality, dynamic CT angiography has to be considered to rule out ischemic bowel disease. High index of suspicion, early recognition and aggressive multi-disciplinary treatment approach could be lifesaving.

SS 18 AB-06 10:40CT colonography and natural killer cells activity test in screening for colorectal cancerZhandos Amankulov1, Zhamilya Zholdybay1, Madina Orazgalieva2 1Asfendiyarov Kazakh National Medical University, 2Kazakh Research Institute of Oncology and Radiology, Kazakhstan. [email protected]

PURPOSE: Colorectal cancer (CRC) is the fourth common malignancy and third leading cause of cancer-related deaths in Kazakhstan. CRC screening program has been running in Kazakhstan since 2011 with iFOBT as a primary screening tool and endoscopy for the follow-up. Sensitivity and specificity of iFOBT, and patient compliance with endoscopy was low. Computed tomography colonography (CTC) is reported to be feasible for diagnosis of CRC. Also, natural killers (NK cells) play a key role in anti-cancer immunity. Studies have shown the correlation between low activity of NK cells and a high risk of cancer. The aim of this trial is to assess the feasibility of CTC and NK activity test as

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primary methods of screening for CRC.MATERIALS AND METHODS: It was a prospective study of 322 individuals, aged 40 to 70 years, who were invited for CRC screening. According to the results of tests, 4 groups were formed: normal (1), non-neoplastic changes (2), benign (3) and malignant neoplasms (4). Lesions found on CTC were characterized by size, location, and morphologic appearance. The activity of NK cells was measured with “NK Vue” test system. The revealed pathologies were histologically confirmed.RESULTS: The median age of participants was 54.8 years (45-73), 111 men and 211 women. Five new CRC cases were found. Adenomatous polyps (more than 6 mm) were observed in 21.3% and advanced adenomas (more than 10 mm) in 12.7%. The sensitivity and specificity of CTC in the diagnosis of CRC were 1.0 and 0.87, respectively, and 0.9 and 0.77 for polyps more than 6 mm. The median level of NK cells activity in CRC patients was 66.0 pg/ml; in individuals with polyps - 308.7 pg/ml; in patients with non-oncological diseases - 92.4 pg/ml; and in the group "without pathology" was 409 pg/ml. NK cells activity had high sensitivity and specificity in diagnosis of CRC (0.84 and 0.91). Compliance rates were significantly higher for those who underwent screening with CTC and NK cells activity test than group who was screened with iFOBT and endoscopy.CONCLUSION: Preliminary results of the trial showed high sensitivity and specificity of CTC and NK cells activity test in diagnosis of CRC. In the diagnosis of colon adenomas CTC was more reliable. Test for NK cells activity increases diagnostic accuracy of iFOBT. Using these new methods in CRC screening can increase patient compliance and improves screening outcomes.

SS 18 AB-07 10:50CT evaluation of hollow viscus perforation: Correlation with clinical features according to location and causeDong Chan Kim, Mi Hyun Park, Keum Nahn Jee Dankook University Hospital, Korea. [email protected]

PURPOSE: To evaluate the diagnostic sensitivity of CT and to correlate CT findings with clinical features for the hollow viscus perforation according to location and cause.MATERIALS AND METHODS: 168 patients confirmed as perforation of hollow viscus were included in this retrospective study from January 2010 to December 2017. We analyzed initial contrast enhanced CT imaging within 24 hours after symptom onset and evaluated about perforation site, extent of peritonitis

based on pneumoperitoneum, ascites with peritoneal change, contrast extravasation, thickening with/without enhancement of bowel wall, ileus, associated other organ abnormality according to primary location and cause, by consensus of two abdominal radiologists, and reviewed medical record about clinical symptom, morbidity, mortality and etc..RESULTS: Intestinal perforation was confirmed by surgery (n = 159) and by clinical course and radiological findings (n = 9). The primary perforation sites were 40 patients in stomach and duodenum, 85 in jejunum and ileum, and 43 in colorectum. Non-traumatic perforation of gastroduodenum like ulcer or carcinoma was 34 cases, 13 in jejunum and ileum like ischemic or inflammatory enteritis, and 19 in colorectum like carcinoma, infarction, and chronic inflammation. The remaining cases were trauma-related perforation like traffic accident, blunt trauma, penetrating injury, barotrauma, and procedure-related. Regardless of cause, in gastroduodenal or colorectal perforation, there were larger amount of pneumoperitoneum and increased incidence of associated panperitonitis than those of jejunum and ileum (p < 0.05). Regardless of the location, more accurate localization of perforation site was possible in non-traumatic causes than those of traumatic, due to bowel wall thickening with enhancement and surrounding peritoneal change. Regardless of cause or location, perforation site showed usually as wall thickening or surrounding peritoneal change in the remaining cases. For accurate diagnosis of primary perforation site in traumatic cases, localized peritoneal change or surrounding solid organ injuries could be a clue.CONCLUSION: Convergence of meticulous CT analysis and clinical features in suspicious intestinal perforation might be helpful for determining the correct diagnosis of perforation site, proper treatment and prediction of prognosis.

SS 18 AB-08 11:00A full convolutional network-based automatic segmentation of body morphometry on abdominal CT imageHyo Jung Park1, Yongbin Shin1, Kyung Won Kim1, Ji Suk Park1, Taeyong Park2, Jeong Jin Lee2, Seong Ho Park1 1Asan Medical Center, 2Soongsil University, Korea. [email protected]

PURPOSE: To develop full convolutional network (FCN) based artificial intelligence (AI) model and evaluate its performance for quantification of abdominal muscle and fat on abdominal CT.MATERIALS AND METHODS: This study included

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patients referred from various physicians to a central imaging core lab (Asan Image Metrics, Seoul, Korea) for body morphometric analysis on CT. Patients with various diseases as well as healthy individuals were included. A total of 936 patients with 1275 CT scans constituted the study cohort (M:F = 640:312; mean age, 52.1 ± 14.4). They were divided into a training set (901 CT from 562 patients), and an internal validation set (374 CT from 374 patients). From each patient, a single axial CT image obtained on the inferior endplate-level of 3rd

lumbar vertebra was used for the analysis. An image analyst created the manually-drawn segmentation maps of skeletal muscle, visceral fat, and subcutaneous fat, which were used as ground truth. Our AI segmentation model was based on FCN with additional pre- and post-processing steps. In training set, supervised learning using the ground-truth images were used. In validation set, the technical success was evaluated by a radiologist for the appropriateness of AI segmentation maps. Technical performance was evaluated using dice similarity coefficient (DSC) and cross-sectional area (CSA) error. In addition, we performed Bland-Altman analysis and 95% confidence interval (CI) of limit-of-agreement.RESULTS: The technical success rate was (98.9%, 370/374). The reason of technical failure in all 4 cases was subcutaneous edema. For subcutaneous fat, visceral fat, and abdominal muscle, the DSCs were 0.97 ± 0.03, 0.97 ± 0.02, and 0.97 ± 0.02, respectively. The CSA errors were 3.03 ± 4.15%, 2.02 ± 2.61%, and 1.85 ± 2.65%, respectively. The 95% CI of limit-of-agreement on Bland-Altman analysis were 7.60 cm2 (95% CI, 7.10-8.19), 4.30 cm2 (95% CI, 4.01-4.63) and 7.46 cm2 (95% CI, 6.96-8.03), respectively.CONCLUSION: Our FCN-based modified AI model exhibi ted a high performance in the accurate segmentation of abdominal muscle and fat.

SS 18 AB-09 11:10Effect of lowering total volume and injection rate of iodinated contrast media for abdominopelvic CT on the incidence of adverse eventsJung Hee Son, Hyo Jung Park, Seong Ho Park Asan Medical Center, Korea. [email protected]

PURPOSE: Lowering kVp coupled with denoising techniques enables a reduced use of iodinated contrast media for CT without compromising diagnostic performance. While this approach is already used in practice, its effect on adverse events associated with CT contrast injection is not known yet. This study was to determine the effect of lowering the total volume and rate of CT contrast administration on the incidence of adverse events related to CT contrast injection.MATERIALS AND METHODS: From August 2016 to January 2017, 25,466 consecutive patients (M:F = 15,296:10,170; mean age ± SD, 59.1 ± 12.2 years) underwent abdominopelvic CT using a conventional method (control group): 120 kVp, contrast dose of 2 ml/kg (maximum 150 ml), and injection rates of 3 ml/s (18,455 patients) or 4 ml/s (7,011 patients). In comparison, 26,827 consecutive patients (M:F = 15,734:11,093; 59.3 ± 11.6 years) between August 2017 to January 2018 underwent the CT using reduced contrast (intervention group): 100 kVp with iterative reconstruction, 1.5 ml/kg (maximum 130 ml), and 2.5 ml/s (19,437 patients) or 3 ml/s (7,390 patients). The latter protocol was derived to maintain image quality and diagnostic capability through repeated calibration processes. All occurrences of contrast-related acute adverse reactions categorized as severe (hypotension, dyspnea, respiratory arrest, cardiac arrest, or loss of consciousness), moderate, and mild reactions and contrast extravasation during injection were prospectively recorded in a registry. These rates were

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compared between the control and intervention groups.RESULTS: Overall (all severities) rate of acute adverse reactions was 2.38% (605/25,466) and 2.24% (600/26827) for the control and intervention groups, respectively (relative risk = 0.94). The rate of severe acute adverse reactions was 0.05% (14/25,466) and 0.02% (6/26,827) for the respective groups (relative risk = 0.41; NTT = 3,069). Contrast extravasation during injection occurred in 0.22% (56/25,466) and 0.15% (40/26,827) in the respective groups (relative risk = 0.68; NTT = 1,418).CONCLUSION: Lowering total volume and injection rate of iodinated CT contrast media with the adoption of low kVp scan and iterative reconstruction decreases the risks of severe acute adverse reactions and contrast extravasation in addition to the expected benefit of reduced radiation exposure.

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Rectal cancer and pancreas imaging

Chairperson(s)Joonseok Lim Yonsei University College of Medicine,

Severance Hospital, KoreaSeong Ho Park Ulsan University College of Medicine,

Asan Medical Center, Korea

SS 30 AB-01 09:50locally advanced rectal cancer: Diffusion kurtosis imaging for predicting complete regression after neoadjuvant chemoradiotherapyYanyan Xu1, Hongliang Sun1, Wu Wang1, Kaining Shi2 1China-Japan Friendship Hospital, 2Philips Healthcare, China. [email protected]

PURPOSE: To explore the value of diffusion kurtosis imaging (DKI) in predicting tumor complete regression after chemoradiation therapy (CRT) in patients with locally advanced rectal cancers.MATERIALS AND METHODS: 68 patients (M:F = 53:15; mean age, 58.76 ± 10.85 years) underwent pelvis MRI examination before CRT were enrolled in the study. All MRI examinations were performed in 3.0T MR unit (Philips 3.0T Ingenia, Philips Medical System, the Netherlands) including high spatial resolution T2-weighted imaging and diffusion-weighted imaging (DWI) sequences. Totally, seven b values (0, 400, 800 1000, 1200, 1500 and 2000 s/mm2) were adopted and DKI derived parameters (MD, mean diffusivity; MK, mean kurtosist; FA, fractional anisotropy) were measured

independently by two radiologists using IDL 6.3 software (ITT Visual Information Solutions, Boulder, CO, USA). According to final histopathologic results, patients were divided into two groups: complete regression (CR) and non-CR group. The DKI parameters between CR and non-CR groups were compared by using Mann-Whitney test, and relevant diagnostic performance for predicting the response to CRT was evaluated by receiver operating characteristic (ROC) analysis. The area under the ROC curve (AUC) and the optimal cut-off values were calculated, meanwhile sensitivity and specificity were determined. p < 0.05 was considered to indicate a statistically significant difference.RESULTS: Final ly, 9 CR and 59 non-CR were demonstrated after CRT. MD values were significantly lower in CR group than in non-CR group (p = 0.032), while MK and FA values showed different trend (CR group: MK = 0.97 ± 0.20, FA = 0.17 ± 0.03; non-responders: MK = 0.88 ± 0.17, FA = 0.12 ± 0.07). According to ROC curve, AUC values for MD and FA were 0.755 and 0.792, respectively. The optimal cutoff point was 1.087 × 10-3 mm2/s for MD (MD values of CR patients were lower than this value; sensitivity 83.05%, specificity 77.78%), 0.140 for FApre (FA values of CR patients were greater than this value; sensitivity 88.89%, specificity 69.49%).CONCLUSION: The pre-CRT DKI parameters, especially MD and FA, with high sensitivity for tumor complete regression, might be valuable non-invasive index to evaluate response to CRT in locally advanced rectal cancer.

SS 30 AB-02 10:00Optimal patient management after chemoradiotherapy for rectal cancer using magnetic resonance tumor regression grade (mrTRG): A decision curve analysisJieun Byun1, Seong Ho Park2, Jong Keon Jang1, Sang Hyun Choi1 1Asan Medical Center, 2Ulsan University College of Medicine, Korea. [email protected]

PURPOSE: Watch and wait instead of total mesorectal excision is being attempted for patients who show a good response after chemoradiation therapy (CRT) for locally advanced rectal cancer. mrTRG is a well-established imaging method to assess CRT response. However, specific management using mrTRG is yet unclear. We aimed to determine optimal management strategy using mrTRG through correlative pathological and decision curve analyses.MATERIALS AND METHODS: 439 consecutive patients (M:F = 290:149; 62.2 ± 11.4 years) undergoing

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long-course CRT (45-50 Gy+boost dose 4-6 Gy) for mid/low-rectal cancer (cT3-4 or cN+ without metastasis) with post-CRT rectal MRI preoperatively were included. Experienced abdominal radiologists and pathologists evaluated CRT response using mrTRG (1-5) and pathologic TRG (pTRG) by Mandard, respectively, with blinding. mrTRG grades were cross-tabulated against pathologic complete remission (pCR) versus others. With the correlative pathologic data and decision curve analysis, net benefit score (the difference between the expected benefit and harm) was calculated for different mrTRG criteria to select candidates for watch and wait across threshold probability of residual cancer above which the patient would opt for surgery instead of watch and wait. The results were compared among different mrTRG criteria and with surgery-for-all strategy.RESULTS: 88 patients had pCR. The accuracy of predicting pCR was 60.6% (40/66), 22.3% (25/112), and 11.7% (19/163) for mrTRG1 to 3, respectively. For watch-and-wait approach, the net benefit score was higher when it is applied to patients with mrTRG1 compared with mrTRG1-2 or 1-3 for almost the entire range of threshold probabilities. Watch-and-wait for patients with mrTRG1 yielded higher benefit scores than the surgery-for-all strategy with threshold probabilities > 0.39 but lower scores with smaller threshold probabilities. Watch-and-wait for patients with mrTRG1-2 or 1-3 gave higher benefit scores than surgery only with threshold probabilities > 0.63 and > 0.75, respectively, both of which deem clinically unacceptable ranges.CONCLUSION: Watch and wait, if used, should be carefully applied to patients with mrTRG1 (but not to patients with higher mrTRG) as the net benefit can be higher compared with surgery according to the threshold probability (i.e., clinical circumstance).

SS 30 AB-03 10:10Added value of diffusion weighted imaging for evaluating extramural venous invasion in patients with primary rectal cancerJuhee Ahn, Seung Ho Kim, Jung Hee Son, Sung Jae Jo, Jung-Hee YoonInje University Haeundae Paik Hospital, Korea. [email protected]

PURPOSE: To evaluate the added value of diffusion restricted imaging (DWI) to T2 weighted imaging (T2WI) in detecting the extramural venous invasion (EMVI) in patients with primary rectal cancer.MATERIALS AND METHODS: Seventy-nine patients (M:F = 50:29; mean age, 67.4 years; range, 37-87 years) who underwent rectal MRI and subsequently received surgical resection were included. The rectal

MRI consisted of T2WI in three planes and axial DWI (b values, 0, 1000 s/mm2). Two blinded radiologists to pathologic results independently reviewed the T2WI first, and combined T2WI and DWI 4 weeks later. They recorded their confidence score for EMVI with a five point scale (1: definitely negative, 2: probably negative, 3: possibly negative, 4: probably positive and 5: definitely positive). The diagnostic performance of each reading session for each reader was compared by pairwise comparison of receiver operating characteristic curves (ROC). The area under the ROC curve (AUC) was considered as the diagnostic performance. The histopathologic results served as the reference standard for EMVI.RESULTS: For reader 1, the diagnostic performance was not significantly different between the two image sets (AUC, 0.820 and 0.842, p = 0.3582). For reader 2, the diagnostic performance of T2WI was higher than that of combined T2WI and DWI (AUC, 0.747 and 0.697, p = 0.0136).CONCLUSION: There was no added value of DWI to T2WI in detecting EMVI in patients with primary rectal cancer.

SS 30 AB-04 10:20Role of diffusion-weighted imaging (DWI) added to magnetic resonance tumor regression grade (mrTRG) for guiding management after chemoradiotherapy for rectal cancerJong Keon Jang1, Jieun Byun1, Sang Hyun Choi1, Seong Ho Park2 1Asan Medical Center, 2Ulsan University College of Medicine, Korea. [email protected]

PURPOSE: To i nves t i ga te t he pe r fo rmance characteristics of DWI in diagnosing pathologic complete remission (pCR) after chemoradiotherapy (CRT) for rectal cancer and its role when added to mrTRG in guiding post-CRT management.MATERIALS AND METHODS: 339 patients (M:F = 217:122; 62.3 ± 11.9 years) showing mrTRG1-3 on post-CRT MRI, a subcohort of consecutive 439 patients undergoing long-course CRT for mid/low-rectal cancer (cT3-4 or cN+ without metastasis) and subsequent surgery, were included. DWI (b factor, 1000 s/mm2) was interpreted as + or - and, if +, as thin area of restriction in the luminal side alone vs. nodular/geographic restriction scattered in/permeating the wall. DWI was correlated with pTRG by Mandard. DWI accuracy for diagnosing pCR (i.e., pTRG1) was determined. Changes in true and false calls of pCR on MRI by adding DWI compared with when using each mrTRG grade alone to make calls of pCR were assessed. Net benefit scores (the difference

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between expected benefit and harm) were calculated across threshold probability of residual cancer above which the patient would opt for surgery using the decision curve analysis and were compared between use of DWI to determine surgery versus watch-and-wait and either surgery or watch-and-wait driven by mrTRG alone.RESULTS: DWI+ rate showed a linear association with pTRG (p < 0.001). DWI+ patterns (thin luminal vs. scattered/permeating) were not associated with true versus false calls (p = 0.796). The sensitivity and specificity of DWI for diagnosing pCR was 78.6% (66/84) and 66.3% (169/255), respectively. DWI, compared with using each mrTRG grade alone as a criterion for pCR, corrected false pCR calls in 9/26, 53/85, and 107/144 cases for mrTRG1, 2, and 3, respectively, but erased true pCR calls in 7/40, 5/25, and 6/19 cases, respectively. Unlike in mrTRG1 patients, in mrTRG2 and 3 patients, using DWI to determine surgery versus watch-and-wait yielded net benefit scores that were greater than watch-and-wait for almost the entire range of threshold probabilities and greater than surgery for high-threshold probability ranges (> 0.61 for mrTRG2 and > 0.73 for mrTRG3).CONCLUSION: DWI has fair sensitivity but relatively low specificity for diagnosing pCR. DWI may be helpful for mrTRG2 and 3 patients for selecting management after CRT but may not be so for mrTRG1 patients.

SS 30 AB-05 10:30A comparative study between non-contrast MRI and IV gadolinium enhanced MRI in local staging of rectal malignancyAkhil Kulkarni, Aisha M Manzoor, Royce DSA SSIMS & RC, Davangere, India. [email protected]

PURPOSE: To compare non-contrast MRI and IV gadolinium enhanced MRI in evaluation of colorectal malignancy. To find out added advantage of contrast enhanced over non enhanced MRI.MATERIALS AND METHODS: The study involved analysis of MRI of 60 patients with clinical suspicion and/or histopathologically proven ano-rectal malignancy. Endorectal coils was not used because of cost factor. Bowel preparation was given for the patient one day prior and on the day of examination in the form of laxative (Bisacodyl). Rectal enema with approximately 250 ml plain water was done for distention of rectal lumen which helps in better delineation of tumor. All MR imaging examinations was performed on a 1.5-T magnet MR system (GE SIGNA). The sequences done include axial T2 FSE/TSE, coronal T2 FSE/TSE FS, axial and coronal 2D FIESTA, axial diffusion and ADC. IV gadolinium at a dosage of 0.01 ml/kg was used as contrast. Post-contrast three planar T1 sequences was performed. The MR images was evaluated by two radiologists (pre- and post-contrast IV gadolinium contrast MRI) who was blinded to each other and to the histologic results and the findings was compared.RESULTS: Out of 60 patients, 8 patients presented at T1 staging, 20 patients at T2 staging, 28 patients at T3N1/2 staging and 4 patients at T4 staging. All lesions were showing diffusion restriction. Gadolinium enhanced MRI did not significantly improve the diagnostic accuracy in staging of T1, T2 and T3. From our study we found out that contrast enhanced imaging further adds to confusion and overstaging of T1, T2 and T3 staging. Mesorectal fascia and metastatic lymph nodal involvement can be very well appreciated from routine MR sequences and hence gadolinium enhanced study did not add additional information. We could conclude from the study that gadolinium enhanced study has added advantage over non contrast study in local invasion of adjacent organs and extravascular mural invasion and thereby help in T4 staging. Metastatic lymph node scan be very well appreciated with non-contrast imaging.CONCLUSION: Post-contrast evaluation for local staging of rectal malignancy should not be routinely performed. It has to be reserved in equivocal cases to assess adjacent local invasion of rectal malignancy ie in T4 staging. This will help in saving time, energy, money and resources.

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SS 30 AB-06 10:40Association between oncogenic RAS mutation and radiologic-pathologic findings in patients with primary rectal cancerSung Jae Jo, Seung Ho Kim, Jung-Hee Yoon Inje University Haeundae Paik Hospital, Korea. [email protected]

PURPOSE: To evaluate the association between various radiologic-pathologic findings and oncogenic Kirsten-ras (KRAS) mutation in patients with primary rectal cancer.MATERIALS AND METHODS: Seventy-five patients with primary rectal cancer who underwent rectal MRI were included. The rectal MRI consisted of T2-weighted images in three planes, pre-and post-contrast enhanced T1-weighted images and axial diffusion weighted images (b factors, 0, 1000 s/mm2). Two radiologists reviewed the MR images in consensus and measured the axial and longitudinal tumor lengths, apparent diffusion coefficient (ADC) and relative contrast enhancement (signal intensity difference of tumor on pre-and post-contrast T1WI/ signal intensity of tumor on pre-contrast T1WI). The associations between the qualitative (tumor

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stage, node stage, lymphatic invasion, venous invasion, and perineural invasion) and quantitative data (tumor length, ADC, relative contrast enhancement) and KRAS mutation were statistically analyzed by Fisher’s exact test for qualitative data and Welch test for quantitative data. Molecular biologic results served as the reference standard.RESULTS: The ratio of axial to longitudinal tumor length in KRAS positive group (n = 41) was higher than that of the negative group (n = 34) (0.29 ± 0.15; 0.22 ± 0.08, p = 0.0117). The mean ADC of the positive group was not significantly different from the negative group (0.96 ± 0.16 × 10-3 mm2/s; 0.98 ± 0.17×10-3 mm2/s, p = 0.6593). The relative contrast enhancement showed no significant difference between the two groups (1.58 ± 0.89, 1.35 ± 0.82, p = 0.2692). Other qualitative findings did not show any significant difference (p > 0.05).CONCLUSION: The ratio of axial to longitudinal tumor length only showed a significant difference according to KRAS mutation in patients with primary rectal cancer.

SS 30 AB-07 10:50Percutaneous US-guided core biopsy versus endoscopic ultrasound-guided core biopsy in solid pancreatic lesions: Propensity-score matchingEunsol Lim1, Jin Woong Kim2, Jong eun Lee2, Seul Gi Choi2, Sang Soo Shin1, Sukhee Heo2, Yong Yeon Jeong2 1Chonnam National University Hospital, 2Chonnam National University Hwasun Hospital, Korea. [email protected]

PURPOSE: To compare diagnostic accuracy between percutaneous ultrasound (US)-guided core biopsy (PUSB) and endoscopic US-guided core biopsy (EUSB) for solid pancreatic lesions.MATERIALS AND METHODS: 272 and 75 patients underwent PUSB and EUSB for pancreatic solid lesions, respectively, were enrolled. Patients demographics and tumors characteristics between PUSB and EUSB were assessed. The diagnostic rate, sensitivity, and negative predictive value (NPV) for each technique were compared before and after one-to-two propensity-score matching. Procedure-related complications and procedure time were also compared.RESULTS: Before matching, the mean tumor size were 41.8 mm and 37.6 mm in PUSB and EUSB groups, respectively (p = 0.036). The body mass index (BMI) were 22.5 kg/m2 and 23.3 kg/m2 in PUSB and EUSB groups, respectively (p = 0.046). The diagnostic rate, sensitivity, and NPV were 94.7%, 100%, and 39.1%, respectively, in PUSB group and were 84.7%, 100%, and 21.4%, respectively, in EUSB group. After matching, tumor size and BMI were not different between two

groups (p > 0.05). The diagnostic rate, sensitivity, and NPV were 94.5%, 100%, and 50%, respectively, in PUSB group and were 84.5%, 100%, and 15.4%, respectively, in EUSB group. Complications rates were 4% and 2.4% in PUSB and EUSB groups, respectively (p > 0.05). The mean procedure time was 8.0 and 25.2 minutes in PUSB and EUSB groups, respectively (p < 0.001).CONCLUSION: The d iagnost ic accuracy and complication rate were comparable for solid pancreatic lesions between PUSB and EUSB. The procedure time was shorter in PUSB groups. Therefore, PUSB could be considered as an alternative diagnostic technique for solid pancreatic lesions.CLINICAL RELEVANCE: Percutaneous ultrasound-guided core biopsy is an accurate, safe, and fast technique for the pathologic confirmation of solid pancreatic lesions, because it can yield sufficient amount of tissue cylinders for thorough histological evaluations.

SS 30 AB-08 11:00Early prediction of the severity of acute pancreatitis using radiological and clinical scoring systems with classification tree analysisHye Won Choi1, Hyun Jeong Park1, Seo-Youn Choi2, Jae Hyuk Do1, Ara Ko1, Na Young Yoon3, Eun Sun Lee1 1Chung-Ang University Hospital, 2Soon Chun Hyang University College of Medicine, 3College of Business, Korea Advanced Institute of Science and Technology, Korea. [email protected]

PURPOSE: To develop a decision tree model for early prediction of the severity of acute pancreatitis using clinical and radiological scoring systems.MATERIALS AND METHODS: In a retrospective study, 192 acute pancreatitis patients, who underwent CT (< 72 h after symptom onset), were divided into two cohorts: a training cohort (n = 115) and a validation cohort (n = 77). Univariate analysis was performed to identify significant parameters for prediction of severe acute pancreatitis in the training set. For early prediction of disease severity, classification tree analysis was constructed using significant scoring systems demonstrated by univariate analysis. To assess the diagnostic performance of the model, we compared the area under the receiver-operating curve (AUC) with selected each single parameter. We also evaluated the diagnostic performance in the validation set.RESULTS: APACHE-II, BISAP, EPIC, and Balthazar grade were included in the classification tree analysis model. In training set, our classification tree analysis model showed a trend of higher AUC (0.853, 0.835,

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0.842, 0.739, 0.700, all ps > 0.0125) with achieving higher specificity and accuracy (100%, 94.8%, all ps < 0.0125) comparable with each single parameter. In the validation set, the CTA model achieved similar diagnostic performance to the training set with AUC of 0.833.CONCLUSION: Our classification tree analysis model consisted of clinical and radiological scoring systems and may be useful for early prediction of the severity in acute pancreatitis and identification of high-risk patients, who requiring close surveillance.

Fig. 1. Decision tree model for the prediction of the severity of acute pancreatitis (AP) generated by classification tree analysis in the training set of 115 patients. Data are number of cases with percentages in the parentheses. Group A = non-severe acute pancreatitis (NAP); Group B = severe acute pancreatitis (SAP). Boxes with bold double-line depict the subgroup of AP with high probability of classification in the SAP. Boxes with dotted line depict the subgroup of AP with high probability of classification in the NAP

Fig. 2. Decision tree model for the prediction of the severity of acute pancreatitis (AP) generated by classification tree analysis in the validation set of 77 patients.

SS 30 AB-09 11:10Usefulness of CT HU histogram analysis on preoperative precontrast CT in predicting pancreatic fistula after pancreaticoduodenectomyWonju Hong, Hong-Il Ha, Sang Min Lee, Jung Woo Lee, Kwanseop Lee Hallym University Sacred Heart Hospital, Korea. [email protected]

PURPOSE: To evaluate the effectiveness of CT Hounsfield unit histogram analysis (HUHA) to predict pancreatic fistula (PF) development and to demonstrate that degree of pancreas softness by surgeon’s palpation is correlated to HUHA.MATERIALS AND METHODS: Forty-two patients who underwent pancreaticoduodenectomy were included in this retrospective study. PF was classified according to the International Study Group on Pancreatic Fistula Definition. Two radiologists assessed HUHA and mean CT HU value by drawing ROIs at the level of the pancreatojejunostomy site on axial and sagittal scans of precontrast images. HUHA was divided into three categories: A ≤ 0, 0 < B < 30, and 30 ≤ C. Each HUHA value in ROI was calculated as percentage of the entire area by the commercial 3D analysis software (Aquarius iNtuition v4.4.12; TeraRecon Inc., Foster City, USA). Texture of pancreatic parenchyma was evaluated as soft or hard, by the surgeon’s manual palpation.RESULTS: A clinically relevant PF was observed in 17 patients. PF group showed significantly higher HUHA-A than non-PF group (p = 0.001). Mean CT HU value was not significantly different between two groups (p = 0.075). There was moderately strong correlation between HUHA-A and PF development (r = 0.502). AUC to predict PF development was 0.757 in HUHA-A and 0.639 in mean CT HU (p = 0.004). AUC of HUHA-A and mean CT HU value to predict pancreas softness was 0.841 and 0.788, respectively (p = 0.405).CONCLUSION: HUHA-A on preoperative precontrast CT image enables to predict PF development and showed high predicting performance of pancreas softness.

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Hepatic malignancy: Diagnosis, techniques and others

Chairperson(s)Joon Koo Han Seoul National University College of

Medicine, Korea Jeong-Sik Yu Gangnam Severance Hospital, Yonsei

University College of Medicine, Korea

SS 32 AB-01 16:00Association between additional use of MRI with gadoxetic acid and overall survival in patients with hepatocellular carcinoma Tae Wook Kang, Seong Hyun Kim, Young Kon Kim Samsung Medical Center, Korea. [email protected]

PURPOSE: Additional use of gadoxetic acid as a magnetic resonance (MR) imaging contrast agent has increased for patients with hepatocellular carcinoma (HCC) for diagnostic work-up. However, data on clinical outcomes according to the use of this agent remain limited. To examine whether additional MR imaging with gadoxetic acid can increase overall survival in patients with HCC compared to computed tomography (CT) only or CT and MR imaging with other contrast agents.MATERIALS AND METHODS: This retrospective nationwide cohort study used the National Health Insurance Service database to evaluate outcomes of patients with HCC who underwent CT with or without additional MR imaging for diagnostic work-up between 2008 and 2010 in Korea. Overall survival of CT versus CT and MRI with gadoxetic acid (CT+MRG group) versus CT and MRI with other contrast agents (CT+MRO group).RESULTS: A total of 30,295 patients with HCC received diagnostic work-up with CT (n = 17,043), CT and MRI with gadoxetic acid (n = 9,345), and CT and MRI with other contrast agents (n = 3,907). Mortality rates were higher in the CT group (36.81 deaths per 100 person-years) and the CT+MRO group (21.88 per 100 person-years) than in the CT+MRG group (15.29 per 100 person-years). After adjusting for age, sex, stage and year of diagnosis, the hazard ratios (HR) for all-cause mortality comparing the CT+MRG group to the CT+MRO group was 0.82 (95% confidence interval [CI] = 0.77, 0.86). The association did not materially change after adjustment for etiology, Charlson index, and initial treatment (fully-adjusted HR = 0.91; 95% CI = 0.86, 0.96). When death risk was evaluated by stage, the association was particularly strong for localized (fully-

adjusted HR = 0.90; 95% CI = 0.83, 0.97). CONCLUSION: In patients with HCC who underwent CT, additional diagnostic work-up with MRG decreased overall mortality, especially localized disease.

SS 32 AB-02 16:10 Feasibility study of generating virtual contrast-enhanced CT images from abdomen non-enhanced CT in patients with hepatocellular carcinoma using conditional generative adversarial networks.Jae Seok Bae1, Hwiyoung Kim2, Jung Hoon Kim1, Joon Koo Han3

1Seoul National University Hospital, 2Severance Hospital, 3Seoul National University College of Medicine, Korea. [email protected]

PURPOSE: To investigate feasibility of generating virtual contrast-enhanced CT (CECT) from abdomen non-enhanced CT (NECT) in patients with hepatocellular carcinoma (HCC) by using a deep learning method with a conditional generative adversarial network (cGAN).MATERIALS AND METHODS: Using 350 patients with pathologically confirmed HCC who underwent preoperative CT, we divided into the training set (300 patients with 67,780 images) and the test set (50 patients with 7144 images). We trained a cGAN to generate virtual CECT images from their corresponding CECT images. A generator convolutional neural network (CNN) was trained to transform NECT images into CECT images, while an adversarial discriminator CNN was simultaneously trained to distinguish the output of the generator CNN from real arterial phase CT images. The result of this discriminator was used as an adversarial loss for the generator. We first used the images of the training set to train a cGAN model for approximately 5 days with 6 TITAN Xp GPUs and the trained model was utilized to generate virtual CECT from NECT images of the test set. To evaluate the sensitivity for detection of hepatic focal lesions, two radiologists evaluated the NECT images of the test set and then re-evaluated the NECT images in conjunction with virtual CECT images generated by cGAN. We also graded the degree of enhancement of major abdominal organs and vessel from no enhancement (0) to perfect enhancement (3).RESULTS: Using the NECT images only, 82% (41 of 50) of hypervascular HCCs was detected. With virtual CECT images, additional five lesions were detected to yield 92% (46 of 50) of sensitivity. In terms of degree of enhancement, abdominal aorta showed perfect enhancement in all cases (n = 50), kidney and spleen showed perfect (94%, n = 47 for both) or moderate (6%, n = 3 for both) enhancement, pancreas demonstrated moderate enhancement in all cases (n = 50), and

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the liver showed mild (98%, n = 49) or no (2%, n = 1) enhancement.CONCLUSION: cGAN-based generation of virtual CECT is feasible and is might be helpful for detection of hypervascular hepatic focal lesion.

SS 32 AB-03 16:20Comparison of low kVp CT and dual-energy CT for the evaluation of hypervascular hepatocellular carcinoma in patients at high risk for HCC: Image quality, radiation dose, and lesion conspicuityJeongin Yoo1, Jeong Min Lee1, Ijin Joo1, Eun Sun Lee2, Siwon Jang1, Sun Kyung Jeon1 1Seoul National University Hospital, 2Chung-Ang University Hospital, Korea. [email protected]

PURPOSE: To compare low kVp imaging (90-kVp) and dual energy CT imaging for evaluation of hypervascular hepatocellular carcinoma (HCC) in patients at high risk for HCC with regard to image quality, radiation dose, and lesion conspicuity.MATERIALS AND METHODS: A total of 209 patients with chronic liver disease underwent multiphasic liver CT on a 3rd generation dual-source CT scanner (Somatom Force) using either 90 kVp scan (n = 86) or dual source dual energy (DE) scan (80-kVp and 150-kVp with 0.6 mm tin filter) (n = 123) during arterial phase for evaluation of HCC. There were 36 patients with 49 lesions and 50 patients without HCC in the low kVp group and 60 patients with 78 HCC lesions and 63 patients without HCC in the DECT group. Rotation time was 0.5 s, pitch 1.0 and the chosen detector collimation 192 × 0.6 mm for both tube systems. The iobitridol 350 mgI/mL (Xenetics®, Guerbet) was intravenously injected at a dose of 520 mgI/kg body weight. DE scans were reconstructed into a blended image with a mixed ratio of 0.6 (60%, 80 kVp and 40%, 150 kVp), 40 keV and 50 keV image sets. Contrast-to-noise ratio (CNR) of HCCs, the liver, and the abdominal aorta and image noise were assessed quantitatively. Volume CT dose index (CTDIvol) and dose-length product (DLP) for scans obtained during arterial phase with the two protocols were recorded.RESULTS: DE scans with blended image, 40 keV image, and 50 keV image achieved significantly higher CNR of HCC to liver than low kVp scan. There was no statistically significant difference in liver to muscle CNR between low kVp imaging and DE blended image. The highest aorta to muscle CNR was yielded by DE 40 keV image, followed by DE 50 keV, DE blended, and low kVp images in order. Mean image noise was significantly lower with DE blended image than with low kVp image. There was also no significant difference between two

protocols in the respective of CTDIvol and DLP.CONCLUSION: Dual-energy CT scan with 80 kVp and 150 kVp demonstrated better CNR of HCC to liver, lower image noise, and comparable radiation dose to the low kVp CT scanning protocol.

SS 32 AB-04 16:30Technical success rates and reliability of spin-echo echo-planar imaging MR elastography in patients with chronic liver disease or liver cirrhosisSang Lim Choi, Eun Sun Lee, Hyun Jeong Park, Byung Ihn Choi Chung-Ang University Hospital, Korea. [email protected]

PURPOSE: To determine the technical success rates of MR-elastography (MRE) according to based sequences, i.e.) gradient-recalled echo (GRE) and spin echo planar imaging (SE-EPI) sequences in the same study population with chronic liver disease or liver cirrhosis. In addition, to compare liver stiffness (LS) values between GRE-MRE and SE-EPI MRE in expiration as well as inspiration phases.MATERIALS AND METHODS: Eighty-four patients who underwent MRE (mean age, 62 years; male patients, 59 [72.2%]) from November 2017 to March 2018 were included in this retrospective study. MRE was performed at 3.0T based on GRE and SE-EPI in expiration as well as inspiration. Technical failure of MRE was determined, if there was no pixel value with a confidence index higher than 95% and/or no apparent shear waves imaged. LS measurements were performed using free-drawing ROI by two observers in consensus for each dataset. For evaluation of relative clinical factors regarding technical success rate of MRE, we assessed etiologies of liver disease, presence of ascites, height, weight and BMI of patients. Statistical analysis was performed with Fisher’s exact test, paired t-test and independent t-test.RESULTS: Technical success rate of MRI in SE-EPI was significantly higher than GRE (98.8% vs. 83.3%, p < 0.05). On the basis of univariate analysis, height, weight were significantly associated with failure of MR elastography (p < 0.05). The mean LS of GRE and SE-EPI in expiration were 3.18 kPa and 3.28 kPa, respectively, and there was no significant difference (p > 0.05). However, in inspiration the LS values were significantly higher on both GRE and SE-EPI (3.39 kPa vs. 3.21 kPa, p = 0.0233; 3.53 kPa vs. 3.35 kPa, p = 0.0029).CONCLUSION: SE-EPI based MRI shows significant higher technical success rate. Regarding patient’s respiration, LS values appeared to be significant higher in inspiration phase. There was no significant difference between the mean LS of GRE and SE-EPI.

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SS 32 AB-05 16:40Characterization of focal liver lesions using stretched exponential model: Comparison with monoexponential and biexponential diffusion-weighted MRIHyung Cheol Kim, Nieun Seo, Yong Eun Chung, Jin-Young Choi, Mi-Suk Park, Myeong-Jin Kim Severance Hospital, Korea. [email protected]

PURPOSE: To evaluate the ability of stretched-exponential model of diffusion-weighted imaging (DWI) for characterization of focal liver lesions (FLLs), compared with apparent diffusion coefficient (ADC) and intravoxel incoherent motion parameters.MATERIALS AND METHODS: A total of 180 patients with 180 FLLs who underwent magnetic resonance imaging (MRI) including DWI with nine b values at 3.0T were retrospectively evaluated. The distributed diffusion coefficient (DDC) and intravoxel diffusion heterogeneity index (α) from a stretched exponential model, ADC, true diffusion coefficient (Dt), pseudo-diffusion coefficient (Dp) and perfusion fraction (f) were calculated for each lesion. Diagnostic performances of the parameters were assessed by receiver operating characteristics (ROC) analysis. For twenty patients with treated metastases who underwent hepatic resection, correlation between the DWI parameters and percentage of tumor necrosis on pathology was evaluated using Spearman correlation coefficient.RESULTS: DDC showed the highest area under the ROC curve (AUC, 0.905) in differentiating malignant lesions from benign lesions, followed by Dt (0.903) and ADC (0.866), without significant differences among them (DDC vs. Dt, p = 0.946; and DDC vs. ADC, p = 0.157). For differentiating hypovascular and hypervascular lesions, and for differentiating hepatocellular carcinoma and metastasis, f showed significantly higher AUC than other DWI parameters (p < 0.05). α showed the strongest correlation with the degree of tumor necrosis among the DWI parameters (ρ = 0.655, p = 0.002).CONCLUSION: DDC from stretched exponential DWI showed comparable good diagnostic performance with Dt and ADC for differentiating malignant and benign FLLs. α can be a promising parameter to evaluate the degree of necrosis in treated metastases.

SS 32 AB-06 16:50Intra-individual comparison of T1 mapping using look-locker inversion recovery and volumetric variable flip angle method with B1 inhomogeneity correction in gadoxetic acid-enhanced liver MR imagingJi Eun Kim1, Hyun Ok Kim2, Kyungsoo Bae3, Dae Seob Choi1

1Gyeonsang National University Hospital, 2Gyeongsang National University College of Medicine, 3Gyeongsang National University Changwon Hospital, Korea. [email protected]

PURPOSE: To compare T1 mapping using look-locker inversion recovery (LLIR) and B1 inhomogeneity-corrected volumetric method for estimation of liver function and prediction of hepatic insufficiency and decompensation on gadoxetic acid-enhanced liver MR imaging in the same individuals.MATERIALS AND METHODS: In this retrospective study, 240 patients with normal liver function (n = 51), chronic liver disease (n = 37), or cirrhosis (n = 152) underwent gadoxetic acid-enhanced liver MR imaging, including both T1 mapping methods at 10 and 20 min HBP (hepatobiliary phase). T1 relaxation times of liver (T1Liver-pre, T1Liver-post) and spleen (T1Spleen) were correlated between two methods. ΔT1Liver ([T1Liver-pre - T1Liver-

post]/T1Liver-pre), adjusted T1Liver ([T1Spleen - T1Liver-post]/ T1Spleen), and functional liver volume-to-weight ratio (liver volume on volumetric map/[T1Liver-post * patient's weight]) were calculated. The diagnostic performance of all T1 parameters for identifying cirrhosis and decompensated cirrhosis was compared. The predictive performance of models (serum marker alone, serum marker plus T1 parameter) was compared.RESULTS: The two methods showed strong correlation for T1Liver-post (r = 0.93, p < 0.001) but with significant difference. In depicting cirrhosis, LLIR-adjusted T1Liver

at 10 min HBP showed the highest performance, which is significantly higher than those of other T1 parameters except adjusted T1Liver (p < 0.042). In predicting development of hepatic insufficiency and decompensation, LLIR-adjusted T1Liver (Akaike information criterion [AIC], 57.13; C-index, 0.873) and LLIR-T1Liver (AIC, 43.39; C-index, 0.881) at 10 min HBP showed the best performance, respectively, when added to serum albumin level.CONCLUSION: The two methods showed strong correlation for T1Liver-post but with significant difference. T1 mapping using LLIR at 10 min HBP with obtainment of adjusted T1Liver and T1Liver-post can be the best approach for estimation of liver function and prediction of hepatic insufficiency and decompensation.CLINICAL RELEVANCE: T1 values at both methods cannot be used interchangeably during follow-up. T1

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mapping using LLIR at 10 min HBP with obtainment of adjusted T1LIver and T1Liver-post is recommended for estimation of liver function and prediction of hepatic insufficiency and decompensation.

SS 32 AB-07 17:00 Compressed sensing reconstruction of high resolution hepatobiliary phase imaging at gadoxetic acid-enhanced liver MRI: A feasibility studySun Kyung Jeon1, Jeong Min Lee2, Ijin Joo1, Jeongin Yoo1, Hyo-Jin Kang1, Joon Koo Han2


PURPOSE: To evaluate the clinical feasibility of high resolution (HR) hepatobiliary phase (HBP) imaging using compressed sensing (CS) reconstruction of gadoxetic acid-enhanced liver MRI (Gd-EOB-MRI)MATERIALS AND METHODS: This retrospective study included 136 patients who underwent Gd-EOB-MRI at one of two 3T scanners (Ingenia or Ingenia CX, Philips) including three breath-hold HBP sequences: i) standard HBP using mDixon-3D-fast field echo (FFE) (S-HBP), ii) HR HBP using mDixon-3D-FFE (HR-HBP), and iii) HR HBP using CS reconstruction (CS-HR-HBP). Acquired resolutions were i) 1.2 × 1.3 × 3.0 mm and ii-iii) 1.0 × 1.0 × 1.5 mm). HBP images were obtained with either protocol A (Ingenia CX) using acceleration factors (AFs) for S-HBP, HR-HBP and CS-HR-HBP of 2.8, 6.14 and 6.4, and acquisition times of 13.1, 12.4, and 12.9 sec for S-HBP, HR-HBP, and CS-HR-HBP (n = 58), or protocol B (Ingenia) using AFs of 2.8, 3.4 and 6.4 and acquisition times of 15.3, 17.2, and 14.2 sec (n = 78), respectively. Image quality and diagnostic performance in detecting solid focal liver lesions (FLLs) were compared among the sequences.RESULTS: Using protocol A with similar acquisition times between CS-HR-HBP, S-HBP, and HR-HBP, CS-HR-HBP showed significantly better overall image quality and lesion conspicuity than the other sequences (ps < 0.05). Using protocol B with a shorter acquisition time in CS-HR-HBP than in S-HBP or HR-HBP, CS-HR-HBP showed comparable results in overall image quality and lesion conspicuity to the other sequences (ps > 0.05), albeit with more severe unzip artifacts than S-HBP (p = 0.003). Moreover, the performance of CS-HR-HBP in detecting solid FLLs using protocol A, was better than S-HBP (reader-averaged figures-of-merit (FOM); 0.92 vs. 0.82, p = 0.02), while CS-HR-HBP using protocol B was equivalent to S-HBP or HR-HBP (0.86 vs. 0.80 or 0.90; ps = 0.06, 0.23, respectively).CONCLUSION: CS-HR-HBP was demonstrated to be feasible, providing better image quality and higher

performance in detecting solid FLLs at similar acquisition times to S-HBP and HR-HBP. When using shorter acquisition times for CS-HR-HBP, its performance in detecting solid FLLs was comparable to S-HBP and HR-HBP.

SS 32 AB-08 17:10 Abbreviated gadoxetic acid-enhanced MRI including second shot arterial phase for liver metastasis workupJeong Woo Kim1, Chang Hee Lee2, Yang Shin Park2, Jongmee Lee2, Jae Woong Choi2, Kyeong Ah Kim2, Cheol Min Park2 1Korean Armed Forces Yangju Hospital, 2Korea University Guro Hospital, Korea. [email protected]

PURPOSE: To evaluate feasibility of abbreviated gadoxetic acid-enhanced MRI (AGAM) protocol including second shot arterial phase (SSAP) for liver metastasis workup.MATERIALS AND METHODS: This retrospective study was approved by our IRB and the requirement for informed consent was waived. 108 patients with hepatic metastasis who underwent gadoxetic acid-enhanced MRI using a modified injection protocol were included. Modified injection protocol included routine dynamic imaging after a first injection of 6-mL and SSAP after a second injection of 4-mL. Primary cancer sites consisted of colorectum (n = 59), stomach (n = 16), biliary trees (n = 16), pancreas (n = 7), and others (n = 7). The image set 1 consisted of T2WI, chemical shift image, DWI, and T1-weighted dynamic image including hepatobiliary phase (HBP) (full original protocol). The image set 2 consisted of T2WI, DWI, HBP, and SSAP (abbreviated protocol). Acquisition time was measured in each image set. Visual assessment of vascularity was performed in the original arterial phase (AP), SSAP, and their subtraction images. After excluding patients with ≥ 10 metastatic lesions, 149 lesions in 51 patients were included for detection and characterization analysis. The reference standard was a combination of pathologic result and follow-up image. Two radiologists independently reviewed two image sets regarding the presence and probability of liver metastasis with > 6-week time interval. The diagnostic performance of each image set for each reader was compared by using a jackknife alternative free-response receiver operating characteristic (JAFROC) analysis. The sensitivity and positive predictive value (PPV) were also calculated.RESULTS: Acquisition time was significantly shorter in image set 2 than in image set 1 (1118.3 ± 128.3 vs. 372.8 ± 30.5 sec, p < 0.0001). Regarding the visual assessment of vascularity, 98.8% (85/86) hypervascular

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metastases (hyperintense on the original AP) showed hyperintensity on the SSAP and/or SS subtraction images. For both readers, average JAFROC figure-of-merit was not significantly different between image set 1 and 2 (0.998 vs. 0.997, p = 0.210), and sensitivity and PPV did not show significant difference.CONCLUSION: AGAM protocol including SSAP can provide faster image acquisition with preserving visual vascularity and diagnostic performance for liver metastasis workup.

SS 32 AB-09 17:20Accurate CT-based liver segmentation using deep learningPrima Sanjaya, Sang Joon Park, Jung Hoon Kim Seoul National University Hospital, Korea. [email protected]

PURPOSE: Liver segmentat ion for volumetr ic assessment has emerged as an important tool in medical practice. An accurate detection and segmentation of liver parenchyma in CT is crucial prior to prognosis, tumor load assessment, and monitoring of treatment response. Conventionally, a common segmentation approach is outlined manually. So time consuming work was inevitable. Therefore, in this study, we demonstrated novel method for accurate liver segmentation. The purpose of this study was to develop fast and accurate CT-based liver volumetric segmentation technique and to investigate its performance.MATERIALS AND METHODS: We propose a hybrid liver segmentation technique based on UNET-like architecture, with anatomical analysis. In the pre-processing, we performed several steps for enhancing liver CT images, such as adjusting window level, isotropic conversion, and noise reduction procedures. Furthermore, to enhance the accuracy of segmentation results, we used histogram-based active contour models. In this study, we used in total of 927 cases of CT dataset, separated into 792 unlabeled cases for development set, 85 labeled cases for training set, and final 50 cases for validation with radiologist. The segmentation results from development set furthermore were fetch back into the network performing end-to-end training. For the validation, we computed dice similarity coefficient, intersection over union, precision, and recall score.RESULTS: In the training set, our deep learning model reached its convergence at 95.5 ± 0.1% dice similarity. Of 50 cases in the validation set with radiologist, the results show that our approach obtained 95.6% global dice similarity coefficient score, with 95.5% average of intersection over union, 97.8% recall and 93.5% precision. Our method also achieved the lowest false

positive rate which was 0.15%. As for dice per case, our approach exhibited 93.1 ± 5.8% score (v.2.1), 93.7 ± 6.7% recall (v.3) and 97.5 ± 2.2% precision (v.2) with the least false positive rate down to 0.1 ± 0.07% (v.2.1).CONCLUSION: We have demonstrated a study on liver CT volumetric segmentation which evaluated with radiologist, then we could segment liver parenchyma up to 95.6% global dice similarity and 93.1 ± 5.7% dice per case. This study can be a vital role as a preprocessing step using machine learning techniques for hepatic region analysis and their various diseases studies in the clinical environment.

SS 32 AB-10 17:30Usefulness of noncontrast MR protocol in differentiation between gallbladder carcinoma and benign conditions, manifested as focal mild wall thickening: Comparison with MDCT and contrast MRISoyeon Cha, Young Kon Kim Samsung Medical Center, Korea. [email protected]

PURPOSE: Magnetic resonance imaging (MRI) provides reliable imaging tool for evaluating gallbladder carcinoma but is costly and time-consuming. To compare the noncontrast MRI with multidetector row CT (MDCT) or gadoxetic acid-enhanced whole MRI in the distinction of gallbladder carcinoma from benign disease, manifested as mild focal wall thickening.MATERIALS AND METHODS: We included 101 patients with 36 gallbladder carcinoma and 65 benign diseases, manifested as mild focal wall thickening. Two radiologists reviewed the MDCT and MRI to determine the differential features between malignancy and benignity. Then, two reviewers independently measured the diagnostic performance of MDCT and noncontrast MRI (T1-, T2- and diffusion-weighted images) with/without gadoxetic acid-enhanced images in the diagnosis of gallbladder carcinoma.RESULTS: The benign group more often showed T2 necklace sign or T2 hyperintensity within thickened wall (p < 0.0001) and T1 hyperintensity within wall or gallbladder lumen (p = 0.0002). Meanwhile, malignancy more frequently showed T2 moderate hyperintensity of thickened wall, papillary appearance, diffusion restriction (all ps < 0.0001). There were significant differences in sensitivity (79.2% vs. 95.4% for observer 1; 84.7% vs. 97.2% for observer 2), specificity (80.8% vs. 96.9%; 79.2% vs. 95.4%) between the noncontrast MRI and MDCT (p < 0.05). We found almost similar diagnostic values between the noncontrast MRI and whole MRI (p = 0.479-1.000) for both observers.CONCLUSION: Noncontrast MRI could be a useful

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alternative to gadoxetic acid-enhanced MRI in the diagnosis of gallbladder carcinoma that presents mild focal gallbladder wall thickening on MDCT.

diagnosis of gallbladder carcinoma that presents mild focal gallbladder wall thickening on MDCT.

GB carcinoma

Adenomyomatosis

Chronic cholecystitis

SS 32 AB-11 17:40Role of multislice CT cholangiography (MDCTC) using thin slab minimum intensity projection (MinIP) and multiplanar reformation (MPR) in evaluating patients of biliary obstruction: An Indian experienceVikas Jain, Anupama Tandon Guru Teg Bahadur Hospital & UCMS, New Delhi, India. [email protected]

PURPOSE: Evaluation of biliary obstruction in most western countries is done with MRCP/ERCP; however these are neither widely available nor affordable in most developing countries. Study was planned to evaluate the diagnostic utility of MDCTC using MinIP and MPR in patients of biliary obstruction.MATERIALS AND METHODS: After institutional ethical approval and informed consent 40 patients of biliary obstruction underwent Ultrasound (US) and MDCTC abdomen using predefined protocols. US and MDCTC images with MinIP and MPRs were evaluated independently by two radiologists. Parameters assessed were duct visualization, degree, level and cause of obstruction. These parameters were compared to and diagnostic accuracy of MDCTC calculated taking MRCP / MRI / ERCP as standard.RESULTS: On MDCTC ducts were well visualized in 87.5% up to tertiary level, however, cystic ducts were seen in 22.5% only. Level and degree of biliary obstruction was accurately assessed in 96% cases and correlated well with MRCP/ ERCP. Interobserver agreement was excellent (kappa 0.81 and 0.78).?MDCT accurately detected the cause in 92.5% cases, 55% had malignancy and 35% had calculus disease. Calculi were detected correctly in 76.9% cases, missed in 15.3% (2 cases), over diagnosed in 7.8%; calculi missed were < 5 mm in size and in distal ducts. Detection rate for calculi rose to 100% on combining it with US. Cause detection was 100% in noncalculus causes. In this group, MDCTC scored over MRCP/ ERCP as it gave additional clinically relevant information, in the form of extent, stage, operability and metastasis of the tumor and anatomical variations of extrahepatic ducts and vessels which helped the surgeon. Overall the diagnostic accuracy of MDCT for cause detection was good (sensitivity 94.7%, specificity 50%#, PPV 97.2%, NPV 66.6%# , specificity and NPV not a true representations as there were no controls), in comparison to MRCP/ERCP.CONCLUSION & CLINICAL RELEVANCE: MDCTC is a noninvasive, low cost imaging tool with high diagnostic accuracy and can be a helpful for evaluation of biliary obstruction, particularly in countries where facilities of MRCP/ERCP are limited and often unaffordable. Major limitation of MDCTC is in detection of small calculi which can be overcome by combining with US.

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CECT image without MinIP reformations showing narrowing at proximal CHD, no obvious cause seen.

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MinIP reformation in the same image revealed a hyperdense calculus in GB neck, increasing diagnostic information.

crohn's disease: how to make radiological interpretation -...

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