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

Abstract

Objective

Carbon dioxide (CO₂) has shown potential as a contrast agent in endovascular procedures, but its efficacy in computed tomography angiogram (CTA) (CO₂-CTA) remains unexplored. The aim of this report is to describe feasibility and safety of CO₂-CTA for the technical assessment of aorto-iliac endovascular procedures and evaluate the quality of images.

Methods

CO₂-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 a hybrid CT/angiography system room equipped with a ArtisPheno angiographer and Somatom CT 128-slice sliding gantry (Siemens) and an automatic CO₂ injector (Angiodroid Spa). 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%), or 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 CO₂-CTA in 10 patients for the technical assessment of eight standard endovascular aortic repairs (EVARs), one complex EVAR, and one endovascular reconstruction of the aortic bifurcation. CO₂-CTA was feasible in all cases, and there were no related adverse events. A total of 222 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 arteries (92%), and luminal image quality was excellent in 208 (93.7%); CO₂ layering was detected in nine large arteries (18%). After EVAR, air trapping was detected in two patients (20%) and a type II endoleak in two patients (20%).

Conclusions

These preliminary findings demonstrate that CO₂-CTA is feasible and safe for the technical assessment of aorto-iliac endovascular interventions and provides satisfactory imaging quality. CO₂-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 CO₂-CTA in clinical practice.