ANGIOGRAPHY AND OTHER IMAGING TECHNIQUES

Claudio RabbiaClaudio Rabbia

Department of Vascular and Interventional Department of Vascular and Interventional RadiologyRadiology

Molinette Hospital TurinMolinette Hospital Turin

ANGIOGRAPHYANGIOGRAPHY

Mesenteric angiography is Mesenteric angiography is the most accurate modality the most accurate modality for the diagnosis of acute for the diagnosis of acute lower gastrointestinal lower gastrointestinal bleedingbleeding

inferior inferior mesenteric mesenteric artery artery (IMA)(IMA)

The earliest description of angiographic demonstration of GI The earliest description of angiographic demonstration of GI bleeding was in 1963. Since that time angiography has been bleeding was in 1963. Since that time angiography has been

used in evaluation of GI bleeding, though with varying used in evaluation of GI bleeding, though with varying frequency over time and with the advent of colonoscopy and frequency over time and with the advent of colonoscopy and

scintigraphyscintigraphy

When and why to perform a diagnostic When and why to perform a diagnostic angiography?angiography?

Massive LGI bleedingMassive LGI bleeding Inability to perform colonoscopyInability to perform colonoscopy Failure of colonoscopy to reveal site of bleeding ( up Failure of colonoscopy to reveal site of bleeding ( up

to 52% of cases)to 52% of cases) Recurrent or persistent bleedingRecurrent or persistent bleeding Subsequent endovascular therapySubsequent endovascular therapy

ANGIOGRAPHYANGIOGRAPHY

bleeding rate of at least 0.5 ml/minbleeding rate of at least 0.5 ml/min accurate localization of bleeding accurate localization of bleeding

source (27-86%)source (27-86%) vasodilators, heparin or thrombolytic vasodilators, heparin or thrombolytic

agents increase the sensitivity from 32 agents increase the sensitivity from 32 to 65%to 65%

ANGIOGRAPHYANGIOGRAPHY

•Screen film arteriographyScreen film arteriography

•DSA: higher sensitivity but artifactsDSA: higher sensitivity but artifacts

by bowel motion by bowel motion

ParasympathicolysisParasympathicolysis

Suspended Suspended respirationrespiration

ANGIOGRAPHYANGIOGRAPHY

occasionally specific diagnosisoccasionally specific diagnosis

planning operative resectionplanning operative resection

opportunity for nonsurgical therapyopportunity for nonsurgical therapy

ANGIOGRAPHIC findingsANGIOGRAPHIC findings

active extravasation of contrast active extravasation of contrast material within the bowel lumenmaterial within the bowel lumen

pseudoaneurysmpseudoaneurysm

pathologic circulation – increase of pathologic circulation – increase of vascularizationvascularization

leiomyoma

angiodysplasia

bleeding in bleeding in diverticulitisdiverticulitis

bleeding in diverticulitisbleeding in diverticulitis

ANGIOGRAPHYANGIOGRAPHYclinical sensitivityclinical sensitivity

Typical values are around 60%

Attempts to identify predictors for positive Attempts to identify predictors for positive angiographic findings have shown mixed resultsangiographic findings have shown mixed results

Are there factors to predict which Are there factors to predict which patients will benefit from angiography?patients will benefit from angiography?

a 12-year period reviewa 12-year period review

A positive bleeding scan did not increase the A positive bleeding scan did not increase the percentage of positive angiogramspercentage of positive angiograms

History of prior GI bleeding, transfusions, orthostatic History of prior GI bleeding, transfusions, orthostatic hypotension or tachycardia were not predictors for a hypotension or tachycardia were not predictors for a positive angiogrampositive angiogram

Pennoyer WP, Dis Colon Rectum 1997Pennoyer WP, Dis Colon Rectum 1997

Are there factors to predict which Are there factors to predict which patients will benefit from angiography?patients will benefit from angiography?

Strong correlation with a systolic blood Strong correlation with a systolic blood pressure <100 mmHgpressure <100 mmHg

immediate arteriography rather than immediate arteriography rather than nuclear medicine in hemodynamically nuclear medicine in hemodynamically unstable patientsunstable patients

Nicholson ML, Gut 1998Nicholson ML, Gut 1998

COMPUTED TOMOGRAPHYCOMPUTED TOMOGRAPHY

At this time CT is not commonly performed for At this time CT is not commonly performed for diagnosis of acute GI bleedingdiagnosis of acute GI bleeding

BUTBUT

““Acute Massive Gastrointestinal Bleeding: Acute Massive Gastrointestinal Bleeding: Detection and Localization with Arterial Detection and Localization with Arterial Phase Multi–Detector Row Helical CT”Phase Multi–Detector Row Helical CT”

Yoon W et al Radiology 2006

Arterial phase contrast enhanced Arterial phase contrast enhanced MDCT - advantagesMDCT - advantages

Rapid: very short acquisition timeRapid: very short acquisition time

Non invasiveNon invasive

Accurate in detection and localizing sites of Accurate in detection and localizing sites of acute GI bleeding (arterial phase images)acute GI bleeding (arterial phase images)

Technical aspectsTechnical aspects

120-140 mL of contrast medium (350 mg/mL of 120-140 mL of contrast medium (350 mg/mL of iodine)iodine)

Time of acquisition: 20-25 secTime of acquisition: 20-25 sec Nominal section thickness: 1.5 mmNominal section thickness: 1.5 mm No three-dimensional reconstructionNo three-dimensional reconstruction Delayed (portal phase) scans usually not Delayed (portal phase) scans usually not

performedperformed

MDCT MDCT (multi detector computed tomography)(multi detector computed tomography)

Compared to angiography as the reference Compared to angiography as the reference standardstandard

Sensitivity: 90%Sensitivity: 90% Specificity: 99%Specificity: 99% Accuracy: 100% for localizationAccuracy: 100% for localization

Yoon W, Radiology in pressYoon W, Radiology in press

for detectionfor detection}}

MDCT findingsMDCT findings

Collection of contrast material within the Collection of contrast material within the bowel lumen or extravasated contrast bowel lumen or extravasated contrast material (greater than 90 HU)material (greater than 90 HU)

Focal dilatation of fluid filled bowel Focal dilatation of fluid filled bowel segmentsegment

In addition ability to demonstrate In addition ability to demonstrate morphologic changes in the GI tract morphologic changes in the GI tract (tumors, polyps)(tumors, polyps)

MDCT findingsMDCT findingsmorphologic changesmorphologic changes

Preliminary Preliminary unenhanced CT unenhanced CT scan to detect scan to detect preexisting preexisting hyperattenuating hyperattenuating materialmaterial

Suture materialSuture material

MDCT findingsMDCT findingsmorphologic changesmorphologic changes

Polipoid lesion in thePolipoid lesion in the

sigmoid colonsigmoid colon

adenocarcinoma in the sigmoid coloncolon

MDCT findingsMDCT findingsmorphologic changesmorphologic changes

MDCT findingsMDCT findingsmorphologic changesmorphologic changes

MDCT findingsMDCT findingsactive extravasationactive extravasation

MDCT during MDCT during arterial phase to arterial phase to identify active identify active extravasation of extravasation of contrast material contrast material within the bowel within the bowel lumenlumen

MDCT findingsMDCT findings

ANGIOGRAPHY AND MDCTANGIOGRAPHY AND MDCTwhich better?which better?

The major drawback is that their rate of detection is influenced by several factors, including the rate of bleeding at the time of imaging and the timing of imaging.

Sites of bleeding cannot be demonstrated even in patients with massive GI bleeding because of its intermittent nature.

There is no “gold standard” method as reference

MDCTMDCTadvantages and limitsadvantages and limits

AdvantagesAdvantages

Noninvasiveness and rapidity High accuracy of arterial

phase MDCT MDCT may guide further

endovascular intervention Delayed selective injection

during angiography

LimitsLimits

Impaired renal function Artifacts may obscure

extravasation Lack of therapeutic capability

(angiography, endoscopy, surgery)

time 0time 0 5’ later5’ later

limitations of combining MDCT and angiography include large amount of contrast medium and costs

MAGNETIC RESONANCE MAGNETIC RESONANCE

MRI has a limited role in the MRI has a limited role in the evaluation of acute LGIB evaluation of acute LGIB from arterial sources. In the from arterial sources. In the setting of aneurysms and setting of aneurysms and pseudoaneurysm, magnetic pseudoaneurysm, magnetic resonance angiography resonance angiography (MRA) may be helpful in (MRA) may be helpful in depicting small vascular depicting small vascular abnormalities. abnormalities.

Comparison of three dimensional magnetic resonance imaging in Comparison of three dimensional magnetic resonance imaging in conjunction with a blood pool contrast agent and nuclear conjunction with a blood pool contrast agent and nuclear scintigraphy for the detection of experimentally induced scintigraphy for the detection of experimentally induced

gastrointestinal bleedinggastrointestinal bleeding

100% sensitivity and specificity of 3D MR with 100% sensitivity and specificity of 3D MR with intravascular contrast agentintravascular contrast agent

Strong difference in diagnostic performance in ROC Strong difference in diagnostic performance in ROC analysis in favour of MR imaginganalysis in favour of MR imaging

Hilfiker PR Gut 1999Hilfiker PR Gut 1999

MAGNETIC RESONANCEMAGNETIC RESONANCElimitationslimitations

Lower spatial resolution ( compared with MDCT)Lower spatial resolution ( compared with MDCT) Longer acquisition timeLonger acquisition time Limited availability of equipments for GI emergencyLimited availability of equipments for GI emergency

conclusions

With new CT technology, probably MDCT will With new CT technology, probably MDCT will represent first represent first imagingimaging technique in LGI technique in LGI bleedingbleeding

Further angiography is mandatory if Further angiography is mandatory if endovascular treatment is neededendovascular treatment is needed

Currently there is no indication for MR imagingCurrently there is no indication for MR imaging