The benefit of automated sac volume measurements in postoperative endovascular aortic repair surveillance.

Objective: Abdominal aortic aneurysm (AAA) shrinkage is considered a marker for success following endovascular aortic repair (EVAR). Although maximum diameter is widely used to assess sac behavior, research indicates that changes in AAA morphology do not always affect the maximum diameter. The aim of this study is to investigate if automated AAA sac volume measurements after EVAR can add more nuanced information on sac behavior compared with maximum diameter evaluation alone.

Methods: A retrospective review of all patients treated for AAA with a standard or fenestrated EVAR at two tertiary referral centers was performed. Patients with a pre- and postoperative computed tomography angiography (CTA) ≥ two years after treatment were included. Data were collected using medical charts, radiologic institutional databases, and a deep learning based method called Augmented Reality for Vascular Aneurysm (ARVA). Volume and diameter assessments were automatically performed on CTAs using ARVA. Preoperative sac volumes and diameters were compared with those obtained at least two years after repair. Information on endoleaks (ELs) was collected. Continuous data were tested using t-test, and categorical data were tested using chi-square or Fishers test, depending on sample size.

Results: A total of 89 patients (standard EVAR n=46; fenestrated EVAR n=43) were included in this study. Of the 89 patients, 41 (46%) had sac diameter shrinkage, 38 (43%) had stable sac diameters, and 10 (11%) had diameter sac growth during follow-up. The distribution of sac volume behavior was different amongst these patients: 51 (57%) had volume shrinkage, only 9 (10%) had stable volumes, and 29 (33%) had volume growth. Significantly more patients had sac growth, and fewer had sac stability, when assessed with volume compared with diameter, p=.003 and p<.001, respectively. The increase in patients with volume-assessed sac shrinkage (57% vs 46%) was not statistically significant. Of the 18 (20%) patients with stable sac diameters and simultaneous volume growth, 13 (72%) had ELs (T2ELs: n=9, T1ELs, n=2, T3EL: n=1, and EL of undefined origin: n=1).

Conclusions: This study found that volume-assessed sac behavior identifies more sac shrinkage or growth, and less sac stability than diameter does. If confirmed by larger studies, sac volume assessment should be performed routinely after endovascular repair.