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    Original Research

    Time-resolved CT Angiography for the Detection and Classification of Endoleaks

    Published Online:Jun 1 2012https://doi.org/10.1148/radiol.12111217

    Abstract

    Multiphasic time-resolved CT angiography in patients after endovascular aortic aneurysm repair provides dynamic information at a similar radiation dose as standard triphasic protocols and shows high sensitivity for endoleak detection and classification.

    Purpose

    To assess the feasibility and diagnostic performance of time-resolved computed tomographic (CT) angiography in the detection and classification of endoleaks after endovascular aortic aneurysm repair (EVAR) in high-risk patients.

    Materials and Methods

    The study was approved by our ethics committee. Written informed consent was obtained from all participating patients. Fifty-four patients (42 male and 12 female patients; mean age, 70.9 years ± 9.3 [standard deviation]) with either thoracic (n = 8) or abdominal (n = 46) aortic aneurysms treated with a stent-graft were prospectively included. The patients were examined with a time-resolved CT angiographic protocol consisting of 12 low-dose phases (80 kVp; 120 mAs [effective]; scan range, 27 cm), with 60 mL of iomeprol. Patients with abdominal aneurysm repair also underwent contrast material–enhanced (CE) ultrasonography (US). The time delay between contrast enhancement within the stent lumen and the endoleak was measured. Effective radiation dose was calculated from the scanner protocols. Measures of diagnostic performance for the detection of endoleaks were calculated for time-resolved CT angiography, with CE US serving as the reference standard.

    Results

    All time-resolved CT angiographic data sets were diagnostic. Mean effective radiation dose was 14.6 mSv. Four thoracic and 19 abdominal endoleaks were identified by using time-resolved CT angiography. Seventeen of 19 abdominal endoleaks were confirmed with CE US. This rate resulted in a sensitivity of 94%, a specificity of 93%, a positive predictive value of 89%, and a negative predictive value of 96% for time-resolved CT angiography after abdominal EVAR. Type I endoleaks showed significantly earlier mean peak contrast enhancement (0.28 second ± 0.83) compared with that for type II endoleaks (9.17 seconds ± 3.59, P < .0001).

    Conclusion

    Time-resolved CT angiography with 12 low-dose phases is feasible for patients after thoracic and abdominal EVAR. The protocol approximates the radiation dose of standard triphasic protocols. Its dynamic information differentiates types of endoleaks and shows high diagnostic performance.

    © RSNA, 2012

    Supplemental material:http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12111217/-/DC1

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    Article History

    Received June 16, 2011; revision requested July 26; final revision received December 16; accepted December 29; final version accepted January 20, 2012.
    Published online: June 2012
    Published in print: June 2012