RS01 - An Innovative Prone Contrast Enhancement Computed Tomography Angiography (PASHA) Protocol to Diagnose Concealed Endoleak and Aortic Sac Hygroma

Objectives: Standard 4-phase supine computed tomography angiography (CTA) scans are unable to detect smaller fabric tears ( < 1 - 2 mm) following EVAR, which are erroneously interpreted as type IV or V endoleak (EL). Here, we propose a novel diagnostic technique, 'Prone contrASt enHanced computed tomography Angiography' (PASHA)' that uses time-resolved four-phase CTA protocol to detect and classify concealed ELs.

Methods: We employed PASHA protocol in 46 patients after continuous sac expansion following primary EVAR where the standard 4-phase CTA could not identify the EL source. PASHA protocol uses a prone position during standard 4-phase CTA, which displaces the aorta anteriorly by approximately 5 mm, shortening the anterior cortex distance and allowing fluid transudation due to gravity with maximal EL enhancements.

Results: The average number of CT scans performed before diagnosing EL with PASHA protocol were 3.4 ± 1.5 (range: 1 - 6). PASHA protocol demonstrated EL in all 46 cases that the standard supine 4-phase CTA could not identify. PASHA protocol effectively enhanced the degree of contrast infiltration into the aortic sac in all the patients.

Conclusions: PASHA is a multi-phase positional CTA technique that enhances the degree of contrast infiltration into the aortic sac when micro-leaks are present, increasing the EL detection rate following EVAR and strategically mapping successful future intervention.