Preliminary results of carbon dioxide computed tomography angiogram for the technical assessment of aorto-iliac endovascular procedures

Objective Carbon dioxide (CO 2 ) has shown potential as a contrast agent in endovascular procedures, but its efficacy in CTA (CO 2 -CTA) remains unexplored. The aim of this report is to describe feasibility and safety of CO 2 -CTA for the technical assessment of aorto-iliac endovascular procedures, and evaluate the quality of images. Methods CO 2 -CTA was considered for the technical assessment of aorto-iliac endovascular procedures in patients at risk for contrast-induced nephrotoxicity operated on from March 2023 to April 2024. Procedures were performed in an hybrid CT/angiography system room equipped with a ArtisPheno angiographer and Somatom CT 128-slice sliding gantry (Siemens, Munich, Germany) and an automatic CO 2 injector (Angiodroid Spa, Bologna, Italy). Imaging quality was assessed by two operators; pre-specified vessels of interest were manually segmented and classified based on their size as small, medium, and large. luminal imaging quality was defined by the percentage of vessel lumen area occupied by contrast on axial views, and was graded as excellent (100%), high (75%-99%), moderate (50%-74%) and low (<50%). Arterial wall imaging quality was defined by the capability to discriminate the arterial wall circumference from the arterial lumen on axial views, and was graded as excellent (100% of circumference), high (75%-99%), moderate (50%-74%), or low (<50%). Results We performed CO 2 -CTA in ten patients for the technical assessment of 8 standard endovascular aortic repairs (EVAR), 1 complex EVAR, and 1 endovascular reconstruction of the aortic bifurcation. CO 2 -CTA was feasible in all cases and there were no related adverse events. Two-hundred-twenty-two vessels (large size, n=50; medium size, n=80; small size, n=92) were analyzed for image quality. Overall, wall image quality was excellent in 206 (92%) arteries and luminal image quality was excellent in 208 (93.7%); CO 2 layering was detected in 9 (18%) large arteries. After EVAR, air trapping was detected in 2 patients (20%) and a type 2 endoleak in 2 (20%). Conclusion These preliminary findings demonstrate that CO 2 -CTA is feasible and safe for the technical assessment of aorto-iliac endovascular interventions, and provides satisfactory imaging quality. CO 2 -CTA eliminates the necessity for nephrotoxic agents, making it a viable option for patients with severe chronic renal insufficiency at risk of dialysis. Further studies are warranted to optimize the acquisition protocol and explore the applicability of CO 2 -CTA in clinical practice.