Decoding the Aneurysm Thrombus: Radiomic Signatures of Sac Shrinkage After EVAR

Aneurysm sac shrinkage after endovascular aortic repair (EVAR) is a surrogate marker of effective aneurysm exclusion and favorable outcomes. Radiomics enables quantitative imaging analysis beyond visual assessment and is increasingly applied in cardiovascular imaging. Analysis of intraluminal thrombusmay may provide additional information for identifying patients with different patterns of sac remodeling after EVAR.

This single-center retrospective study assessed whether radiomic features of the intraluminal thrombus extracted from preoperative computed tomography angiography (CTA), alone and in combination with clinical and anatomical variables, were associated with aneurysm sac shrinkage after EVAR. Patients undergoing elective EVAR for infrarenal abdominal aortic aneurysm were included and stratified according to sac shrinkage at 12-month follow-up. Preoperative arterial-phase CTA scans were analyzed. The aneurysm sac was manually segmented using 3D Slicer, and the intraluminal thrombus was selected as the region of interest. A total of 530 radiomic features were extracted using PyRadiomics with Laplacian of Gaussian filtering. Features were standardized and evaluated using the Wilcoxon-Mann-Whitney test, Pearson correlation filtering, and Akaike Information Criterion-based feature selection. Predictive performance was compared among combined clinical-radiomic, radiomic-only, and clinical-only models.

Among 94 patients, 29 showed aneurysm sac shrinkage. Two radiomic features were significantly associated with shrinkage. Younger age (p=0.02), larger aneurysm diameter (p=0.02), and homogeneous thrombus texture were associated with shrinkage, while the absence of COPD was associated with lack of shrinkage. None of the other evaluated clinical or anatomical variables showed a significant association with sac shrinkage. The combined clinical-radiomic model achieved the best performance (AUC 0.76, sensitivity 0.70, specificity 0.75, accuracy 0.73).

Preoperative thrombus radiomic features were associated with subsequent sac shrinkage and provided complementary information when integrated with clinical variables. These findings support the potential role of thrombus radiomics in the characterization of sac remodeling after EVAR and warrant validation in larger cohorts.