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ANGIOGRAPHY AND OTHER IMAGING TECHNIQUES Claudio Rabbia Claudio Rabbia Department of Vascular and...
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Transcript of ANGIOGRAPHY AND OTHER IMAGING TECHNIQUES Claudio Rabbia Claudio Rabbia Department of Vascular and...
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
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 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
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)
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