Validation of a Novel Methodology to Evaluate Changes in the Flare Geometry of Renovisceral Bridging Stent-Grafts After Fenestrated Endovascular Aneurysm Repair

Purpose: To validate a novel method to evaluate changes in the geometry of renovisceral bridging stent-grafts (BSGs) in patients undergoing fenestrated endovascular aneurysm repair (fEVAR). Materials and Methods: Retrospective analysis was conducted of serial computed tomography angiograms (CTAs) of 10 fEVAR patients (31 BSGs) with at least 2 years of CTA follow-up. Centerline reconstructions were made through the fenestrated stent-graft (FSG) and each BSG. Flare geometry was reconstructed based on marker coordinates and a mesh of the aortic lumen. The shortest distance was calculated from the top of the flare circumference to the FSG fabric. The amount of flaring was assessed with the flare to fenestration diameter ratio and BSG compression to diameter ratio (D-ratio). All measurements were performed by 2 observers. Interobserver variability was assessed; results are presented as the intraclass correlation coefficient (ICC) and repeatability coefficient (RC). Results: Excellent interobserver agreement was achieved for BSG diameter and flare to fenestration distance calculations (ICC 0.865 and 0.944; RC 2.2% and 4.5%, respectively). Six patients had BSG-related complications during follow-up: 2 type IIIc endoleaks and 4 BSG occlusions. Five of the 6 BSGs with complications showed a considerable change in the D-ratio compared with the first postoperative CTA. Conclusion: Precise assessment of the geometry of visceral BSGs in fEVAR is feasible with the presented method. Geometrical changes that may precede later complications can be detected, which could aid in localization of the origin, but a larger series of patients is necessary to define its true clinical merit.