Multidetector CT in abdominal aortic aneurysm treated with endovascular repair: Are unenhanced and delayed phase enhanced images effective for endoleak detection?

Purpose: To retrospectively determine the sensitivity and specificity of enhanced, delayed enchanced phase (DEP), and arterial enhanced phase (AEP) multi-detector row computed tomography (CT) for depicting endoleaks during follow-up of endovascular aneurysm repair. Materials and Methods: Fifty patients (two women, 48 men; mean age, 72 years) underwent follow-up multi-detector row CT 1, 6, and 12 months after endovascular aneurysm repair. Unenhanced CT was performed with 2.5-mm collimation; 1-mm was used with AEP and DEP examinations. Two independent readers assessed the presence of endoleak in three reading Sessions: AEP (session A), unenhanced and AEP (session B), and AEP and DEP (session C). At 6- and 12-month follow-up, a fourth set was included: 1-month unenhanced and AEP (session D). Sensitivity, specificity, and positive predictive value of each session were calculated. Triple-phase multi-detector row CT was the reference standard. Results: At 1 month, sensitivity, specificity, and positive predictive value, respectively, were 79%, 75%, and 55% for session A; 93%, 97%, and 93% for session B; and 93%, 78%, and 62% for session C. At 6 months, sensitivity, specificity, and positive predictive value, respectively, were 92%, 68%, and 48% for session A; 92%, 100%, and 100% for session B; and 100%, 84%, and 67% for session C. At 12 months sensitivity specificity, and positive predictive value, respectively,, were 80%, 80%, and 50% for session A; 90%, 98%, and '90% for session B; and 100% and 56% for session C. 80%,, Sensitivity did not significantly differ (P >.05) among reading sessions A, B, and C, whereas specificity and positive predictive, values in session B were significantly higher (P <.001). For 6 and 12-month follow-up, no significant differences (P >.05) were found between sessions D and B. Conclusion: The combination of AEP and unenhanced imaging performed at 1-month follow-up offers improved specificity and positive predictive values compared with AEP alone.. DEP imaging does not, significantly increase sensitivity for detection of endoleaks, but it does depict low-flow endoleaks not seen at AEP.