Type II endoleak after endoaortic graft implantation: diagnosis with helical CT arteriography.

PURPOSE: To retrospectively assess endoleak shapes and locations within aneurysms to differentiate type II from type I and type III endoleaks. MATERIALS AND METHODS: The institutional review board granted an exemption for this HIPAA-compliant study; patient informed consent was not required. A retrospective review of arterial phase helical computed tomographic (CT) studies and medical records was performed for 39 patients (29 men, 10 women; age range, 60-89 years; mean, 78.5 years) who had an endoleak after endoaortic graft implantation for treatment of abdominal aortic aneurysm and who subsequently underwent angiography (n = 25), surgery (n = 8), or long-term follow-up (n = 6) to classify their endoleak into a specific type. At CT, endoleak shape (tubular or nontubular) and location (central or peripheral) were recorded. An endoleak was classified as type II if it contained a peripheral tubular component (PTC) near the aortic wall, with or without an identifiable feeding vessel. Endoleaks without these features were classified as type I or III. The Fisher exact test was used to assess associations between CT findings and endoleak type. RESULTS: There were 22 type II and 17 type I or III endoleaks. CT enabled correct identification of 22 (100%) of 22 type II endoleaks, all of which contained a PTC. Of 17 type I or III endoleaks, only two (12%) contained a PTC and were misclassified as type II endoleaks; the remaining 15 (88%) were correctly classified. Overall, CT enabled correct identification of endoleaks as type II or type I or III in 37 (95%) of 39 patients. PTCs were significantly more common (P < .001) in type II than in type I or III endoleaks, with a sensitivity, specificity, accuracy, negative predictive value, and positive predictive value of 100%, 88.2%, 94.9%, 100%, and 91.7%, respectively. CONCLUSION: A PTC is a statistically significant predictor of type II endoleak in most patients.

Detection of endoleaks after endovascular repair of abdominal aortic aneurysm: value of unenhanced and delayed helical CT acquisitions.

PURPOSE: To assess unenhanced and delayed phase computed tomographic (CT) images combined with arterial phase images for detecting endoleaks after endovascular treatment for abdominal aortic aneurysm (AAA). MATERIALS AND METHODS: CT scans were retrospectively evaluated for the presence of endoleaks after endovascular treatment of AAAs in 33 patients with endoleak (positive group) and 40 patients without evidence of endoleak or aneurysm enlargement (negative group). All patients underwent unenhanced and biphasic contrast material-enhanced CT. The CT scans were reviewed in the following combinations: (a) arterial phase and unenhanced scans (uniphasic/unenhanced set), (b) arterial and delayed phase scans only (biphasic set), and (c) arterial and delayed phase scans with unenhanced scans (complete set). Each set was reviewed by two radiologists blinded to the diagnosis of endoleak. Findings were recorded as positive, negative, or indeterminate for endoleak. RESULTS: Within the positive group, endoleaks were diagnosed with the uniphasic/unenhanced, biphasic, and complete image sets in 30 (91%), 32 (97%), and 33 (100%) patients, respectively. With the uniphasic/unenhanced set, three (9%) endoleaks (seen only on delayed phase images) were missed. With the biphasic set, one (3%) endoleak was interpreted as indeterminate. Within the negative group, uniphasic/unenhanced, biphasic, and complete image sets were negative for endoleaks in 100%, 80%, and 100% of patients, respectively. With the biphasic set, results were indeterminate in 20% of cases. CONCLUSION: A delayed CT acquisition enables detection of additional endoleaks, while an unenhanced acquisition helps eliminate indeterminate results. Thus, both acquisitions contribute to accurate diagnosis of endoleaks when combined with an arterial phase acquisition.