Volumetric analysis of the aneurysmal sac with computed tomography in the follow-up of abdominal aortic aneurysms after endovascular treatment

Purpose. Our aim was to assess the usefulness of volumetric analysis for the follow-up of abdominal aortic aneurysms after endovascular repair (EVAR) and operator independence of the method. Materials and methods. We retrospectively evaluated 99 computed tomography (CT) exams of 33 patients. Two blinded operators assessed the volume before treatment and after EVAR at 1-3 and 12-24 months. Friedman's statistical test was used to assess the reproducibility of the method. The time required for postprocessing by the two operators was compared. Results. One patient was excluded. Twenty-one patients showed no endoleak: 12/21 showed a volume reduction at both follow-up scans (9.7% and 19.5%, respectively); 8/21 showed an early volume increase (9.8%) with a late reduction (10.5%); 1/21 patient showed a volume increase at both follow-up scans (endotension). Eleven patients had an endoleak (one type I, nine type II and one type III); 4/9 type II endoleaks showed a volume reduction at both post-EVAR scans (8.5% and 19.5%). All other cases showed a volume increase after EVAR (type II 15.4%/16.8%, type I 24.1%/9.1%, type III 8%/10.7%). The Friedman statistical test assessed operator independence with p<0.001. Mean difference between the two operators was 0.9% (0-4.3%). Conclusions. CT volume analysis is an accurate and reproducible modality for the follow-up of abdominal aortic aneurysms after EVAR. At early follow-up, contrast-enhanced CT remains mandatory to identify small endoleaks. For later follow-up, volumetric analysis would eliminate the need for contrast material in asymptomatic patients with stable or decreasing aneurysm volume.