High-pitch carbon dioxide contrasted CT angiography: pilot study

This study was designed to evaluate CO2 computed tomography angiography (CO2-CTA) of the iliac and lower limb arteries in patients with contraindications for iodinated contrast agent (ICA).

Five patients with contraindications for ICA were examined using CO2-fluoroscopic enhanced angiography (CO2-FLA) and CO2-CTA using a high-pitch examination protocol. Objective (vessel diameter) and subjective (visual score) image quality parameters were evaluated. Pathological findings in both modalities were compared.

CO2-CTA was feasible in all patients without adverse side effects, except for CO2 injection-associated pain. Objective vessel analysis revealed no significant difference in diameters as determined by CO2-CTA and CO2-FLA (0.44 ± 0.4 and 0.46 ± 0.41 mm, p = 0.93). CO2-CTA had on average a higher image-quality score (2.6 ± 1.0 vs. 2.3 ± 1.0, p = 0.009). While for pelvic and upper leg CO2-CTA advantageous (3.1 ± 0.74 vs. 2.7 ± 0.9, p = 0.0014) at good quality scores, for calf vessels no significant improvement was visible (1.9 ± 1.0 vs. 1.7 ± 0.9, p = 0.49) and scores were poorer.

CO2-CTA with high-pitch CT was feasible in a limited number of patients. Image-quality scores were on average higher for CO2-CTA than for CO2-FLA, while limited imaging quality in the vessels below the knee needs further work on the CT protocol. An added value of cross-sectional imaging was apparent but needs further quantification.