Inter-Center Radiation Variability in CO 2 -Guided EVAR: Lessons From the Zero Iodine Contrast Multicenter Prospective Study

Introduction: Current diagnostic reference levels (DRLs) for endovascular aortic repair (EVAR), based on iodinated contrast media (ICM) protocols, range from 100 to 200 Gy·cm 2 . As CO 2 is a negative contrast agent requiring digital subtraction angiography (DSA) for visualization, it may be associated with increased radiation exposure. This multicenter study presents the largest prospective data set to date evaluating radiation dose during EVAR using CO 2 angiography alone with an automated injector. Methods: A prospective, multicenter, nationwide, nonrandomized, investigator-initiated observational study of dosimetry recorded during EVAR procedures with CO 2 as exclusive contrast medium was conducted. Primary endpoints included dose-area product (DAP) and reference air kerma ( K ar ) measurements across all participating centers. Secondary objectives focused on evaluating optimization strategies to reduce radiation exposure for both patients and operators at a single investigational site. Results: A total of 293 patients were enrolled across 10 centers, between January 2023 and January 2024, median DAP and K ar were 189 Gy·cm 2 (interquartile range [IQR] 107-285) and 626.5 mGy (IQR 145.5-1373.5), respectively, with significant inter-center variability (all p