IMAGING IN INFLAMMATORY BOWEL

DISEASE

DR.KHYATI VADERA REFERENCES: RADIOGRAPHICS RESIDENT DOCTOR RUMACK M.D RADIODIAGNOSIS RADIOLOGY ASSISTANT MEDICAL COLLEGE BARODA SSG HOSPITAL

• INTRODUCTION• DEFINATIONS• IMAGING MODALITIES• DIFFERENCE BETWEEN CHRON’S AND UC• DIFFERENTIAL DIAGNOSIS• CONCLUSION

PROTOCOLS

Group of chronic disorders that cause inflammation and ulceration in small and large bowel.

Mainly two most common diseases are –chron’s disease and ulcerative colitis

INTRODUCTION

Idiopathic, chronic, transmural inflammatory process of bowel - affect whole GI system starting from mouth to anus.

Most commonly involved- terminal ileum, ileocaecal valve and caecum with regional enteritis.

SKIP LESIONS ARE PATHOGNOMIC Diagnosed typically between 15-25 years of age

group. No gender predilection, runs in families. Smokers - more affected.

CHRON’S DISEASE

• Chron’s disease can be –Stricturing,Penetrating,Inflammatory

• Etiology – idiopathic, genetic(DR5 DQ1 alleles), immunologic, microbial, psychosocial

• Clinical presentation- diarrhoea, abdominal pain, weight loss

• Intermittent attacks of active disease followed by periods of remission.

• Disease re-activation by triggers like stress, dietary factors, smoking.

• Risk of colonic adenocarcinoma is increased in long standing cases.

• on X-ray- plain radiograph of abdomen is usually helpful in cases of obstruction secondary to chron’s or extraintestinal manifestations

MUCOSAL ULCERS APHTHOUS ULCERS initially  deeper transmural ulcers typically either longitudinal or

circumferential in orientation

when severe leads to COBBLESTONE APPEARANCE may lead to sinus tracts and fistulae

thickened folds due to oedema

pseudodiverticula formation: due to contraction at the site of ulcer with ballooning of the opposite site

STRING SIGN: tubular narrowing due to spasm or stricture depending on chronicity partial obstruction

Barium small bowel follow-through

APTHOUS ULCERSFirst sign of chron’s disease on barium

Cobblestone appearance: due to deep fissuring ulcers around inflammed mucosa

Fissuring ulceration in Crohn's disease - graphically called

`raspberry thorn' ulcers.

String sign: spasm/fibrosis of bowel wall

ILEOILEAL FISTULA: long standing chron’s

ULTRASOUND

limited role, it has been evaluated as an initial screening tool

Typically examination is limited to the small bowel and wall thickness assessed:

Bowel wall thickness should be <3 mm, normally

thickness < 3 mm helps exclude the disease in a low risk patient. thickness > 4 mm helps establish the diagnosis in a high risk

patient.

Ultrasound in the assessment of extraintestinal manifestations.

US image - stricture in a patient with active Crohn's disease

FAT HALO SIGN COMB SIGN Bowel wall enhancement Bowel wall thickening (1-2 cm) -terminal

ileum strictures and fistulae mesenteric/intra-abdominal abscess or

phlegmon formation 

CT FINDINGS

Fat halo sign in chron’s diseaseTransverse CT scan shows the central fatty submucosal layer of low attenuation (*) surrounded by higher-attenuation inner (long arrow) and outer(short arrow) layers grossly corresponding to the mucosa and muscularis propria and serosa of the descending colon, respectively.

COMB SIGN:Hypervascular appearance of the mesentery in active Crohn's disease. Fibrofatty proliferation and perivascular inflammatory infiltration outline the distended intestinal arcades. This forms linear densities on the mesenteric side of the affected segments of small bowel, which give the appearance of the teeth of a comb.

CECT image, coronal section, venous phase - enterocecal fistula with secondary traction of the cecum and right psoas muscle abscess 

CT AND MR ENTEROGRAPHY

Useful for both mural and extramural spread of disease.

Inflammed bowel loops show thickening and contrast enhancement.

Extramural spread: fibrofatty proliferation-thickening of extramural fat

:vascular engorgement(comb sign) Stenosis and strictures

MRI enteroclysis - placement of a nasojejunal catheter through which 1.5-2 L of contrast solution (e.g. water with polyethylene glycol and electrolytes) are injected.

When disease is transmural, with cobblestone appearance, the abnormalities are evident as high T2 signal linear regions.

CT AND MR ENTEROCLYSIS

Introduction of the 12 to 14-F enteroclysis tube (under fluoroscopy or through duodenoscope).

Contrast is administered either on the fluoroscopy table or after transferring the the patient to the CT unit for commencement of the CT scan (usually 1.5-2L of oral contrast).

In the CT unit, the position of the enteroclysis tube is checked in the topogram.

In case negative oral contrast will be used, intravenous contrast injection will be given (approximately 100-150ml).

CT ENTEROCLYSIS

placement of a nasoduodenal tube under fluoroscopic guidance

the small-bowel is distended with 1-3L of methylcellulose (0.5%) and water solution or isosmotic water solution through an electric infusion pump infusion rate:  80-200 mL/min.

multislice HASTE(half-Fourier acquisition single-shot turbo spin-echo) images with fat saturation and unenhanced and enhanced (0.1 mmol/kg gadolinium) T1 coronal and axial fast low-angle shot (FLASH) 2D images with fat saturation are obtained 60 seconds after contrast injection

MR ENTEROCLYSIS

Perirectal phlegmon on axial T2 Single Shot TSE (left) and T1 contrast enhanced (right) sequences. Rectal wall thickening with avid contrast uptake due to active disease. Perirectal phlegmon surrounded by a hyperenhancing perirectal fascia, displaces the rectum anteriorly.

For extraintestinal disease: Perianal fistula/abscess Hepatobiliary manifestations Sacroiliac joints

ROUTINE MRI

Causes superficial ulceration of colon and rectum.

It starts from rectum and retrogradely involves whole colon continuously.

In total colitis- back wash ileitis.

More common in DR2 related genes.

More female predilection, age group 30-40 yrs.

Clinical symtoms- diarrhoea, tenesmus, bleeding per rectum, passage of mucus, crampy abdominal pain.

ULCERATIVE COLITIS

MILD DISEASE: fine granularity

MODERATE: marked erythema, coarse granularity, contact bleeding and no ulceration.

SEVERE: spontaneous bleeding,edematous and ulcerated Long standing cases epithelial regeneration- pseudopolyps, pre

cancerous condition Eventually shortening and narrowing of colon

FULMINANT DISEASE: toxic colitis/megacolon

PATHOGENESIS

Acute UC – descending colon has irregular outline. No fecal residue in colon S/O total colitis

Mucosal inflammation-granular appearance to the surface of the bowel.

Mucosal ulcers are undermined -button-shaped ulcers

Islands of mucosa remain giving it a pseudo-polyp appearance

In chronic cases the bowel becomes featureless with loss of normal haustral markings, luminal narrowing and bowel shortening- lead pipe sign

BARIUM ENEMA

FINE MUCOSAL GRANULARITY- FIRST SIGNNARROWING OF LUMEN

COLLAR BUTTON ULCERS

LEAD PIPE COLON

Back wash ileitis : patulous IC valve and dilated granular terminal ileum

CT FINDINGS

Inflammatory pseudopolyps 

Inflamed and thickened bowel - target appearance, due concentric rings of varying attenuation- mural stratification

In chronic cases, submucosal fat deposition is seen particularly in the rectum fat halo sign

Extramural deposition of fat, leads to thickening of the perirectal fat, widening of the presacral space 

Marked muscularis mucosa hypertrophy-lead pipe sign.

INFLAMMATORY PSEUDOPOLYPS

Wall Thickening- median wall thickeness of colon ranges from 4.7 to 9.8 mm, more severe the disease more thicken the wall

Increased Enhancement- enhancement of the mucosa with no or less enhancement of the submucosa

Loss of haustral markings

MRI

Mri image reveals thickening of colon with loss of haustral markings

DIFFERENCE

CHRON’S DISEASE 70-80%Small bowel

involvement Skip lesions Fat halo sign seen in 8% Apthous ulcers are seen Bowel wall more thicker Irregular serosal surface Perianal fistula/sinus/abscess

more common Creeping fat and abscess are

very common in chronic cases

ULCERATIVE COLITIS 95% cases rectal involvement Continuous spread from rectum

upwards Fat halo sign is commonly seen Collar button ulcers are seen.

Smooth serosal surface Perianal disease rare Mesenteric creeping fat and

abscess are uncommon. Carcinoma is more common in long

standing cases.

Ileocaecal tuberculosis Acute appendicitis Mesenteric adenitis Malignancy Acute diverticulitis Acute epiploic appendagitis Ischaemic colitis Pseudomembranous colitis

DIFFERENTIAL DIAGNOSIS

On BMFT: Mucosal irregularity and rapid emptying Stiffened and thickened folds. Luminal stenosis(hour glass stenosis) Dilated loops and strictures. Aderent fixed and matted loops

Ileocaecal tuberculosis

BMFT:partially contracted caecum with coarse nodular mucosal thickening and a stricture of terminal ileum

TB: narrowing & irregularity of the terminal ileum and rt side of colon.

Increased ileocaecal angle: obtuseGoose neck deformity: fibrosed and retracted caecum

Thickening of ileocaecal junction with surrounding necrotic lymph nodes

Peritoneal thickening in intestinal tuberculosis

• Lymph nodes with peripheral rim enhancement giving multilocular appearance

• Bowel wall thickening

TB CROHN’S

Involvement of terminal ileum

shorter longer

Features Narrowed, thickened, rigid terminal ileum with pulled up ceacum

Asymmetry and cobblestoning

Longitudinal Ulceration

absent present

TUBERCULOSIS VS CHRON’S

Acute appendicitis

Mesenteric adenitis

3 or more nodes with a short-axis diameter of at least 5 mm clustered in the right lower quadrant

Lymphoma

bowel wall thickening: 1-7cm and aneurysmal dilatation:

Lymphoma on ultrasound: hypoechoic vascular mass with multiple pre para aortic lymph nodes

COLORECTAL CARCINOMA

Acute diverticulitis

Pericolic stranding- disproportionate to the amount of bowel wall thickening 

segmental thickening of the bowel wall enhancement of the colonic wall  diverticular perforation - air and fluid into the pelvis

and peritoneal cavity abscess formation (seen in up to 30% of cases)

may contain fluid, gas or both fistula formation-gas in the bladder/direct

visualisation of fistulous tract

Diverticulum of colon

In acute diverticulitis: barium studies are contraindicated

Ischemic colitis

On CT: segmental region of abnormality submucosal oedema may produce low-density ring

bordering lumen (target sign) intramural or portal venous gas mesenteric oedema WITH NON ENHANCING BOWEL

WALL superior mesenteric artery or vein

thrombus/occlusion may be demonstrated

Ischemic colitis(thumb printing ): edematous thickened bowel wall will cause indentations into the air-filled colonic lumen

Pseudomembranous colitis

Pseudomembranous colitis-caused by the bacterium Clostridium difficile due to bacterial overgrowth of the colon in patients who are treated with broad-spectrum antibiotics.

ascites and hyper enhancement of the bowel wall with submucosal edema and edema in the mesocolon.

Ct findings:• Circumferential and

diffuse mural thickening with submucosal edema.

• Prominent haustrae.

• Eccentric polypoid wall thickening.

• Shaggy luminal contour.

Accordion sign

The sign is described as alternating edematous haustral folds separated by mucosal ridges filled with oral contrast material

CONCLUSION

Inflammatory bowel diseases are chronic group of disorders which have a long course of disease with intermittent periods of active disease and remission.

They can be easily diagnosed by multimodality approach combining clinical symptoms , colonoscopy, and radiology.

Conventional radiological investigations like barium studies are still necessary for diagnosis of characteristic intramural changes.

However the CT and MRI investigations are nowadays frequent and less invasive, useful for detection of extraintestinal manifestations of IBD.

Colonoscopy at regular intervals is also must to look for progression of disease and malignancy in long standing cases

THANKS