Four-detector row computed tomographic angiography in the evaluation of infrarenal aorta and peripheral arterial occlusive disease: influence of contrast medium concentration

Abstract

Purpose: To prospectively compare the diagnostic accuracy and quality of vascular enhancement of 2 contrast agents with different iodine concentrations in 4-detector row computed tomographic angiography of abdominal aorta and lower-extremity arteries.

Materials and methods: Forty consecutive patients with peripheral arterial occlusive disease referred for conventional angiography (digital subtraction angiography [DSA]) of the lower extremity were prospectively enrolled in the study and underwent multidetector row computed tomographic angiography (CTA) receiving either 90 mL of iomeprol 400 (Iomeron 400, group A; Bracco Imaging S.p.A., Milan, Italy) or 120 mL of iomeprol 300 (Iomeron 300, group B; Bracco Imaging). Resultant images, both axial, maximum intensity projection, multiplanar reformatted, and volume-rendered 3-dimensional images, were independently evaluated by 2 clinically competent and experienced blinded radiologists for the presence of stenotic and occluded arterial segments using DSA as the standard of reference. Computed tomographic images were also evaluated quantitatively for maximum arterial and venous enhancement, and qualitatively for vascular opacification, venous overlap, and diagnostic efficacy. Quantitative and qualitative results of the 2 study agent groups were statistically compared. Both contrast media were evaluated for safety and tolerability.

Results: From 760 segments, 722 arterial segments were effectively evaluated in the comparative analysis of CTA and DSA. In the evaluation of significant stenoses (>70%) and occluded segments, multidetector row CTA obtained a sensitivity, specificity, and accuracy of 97.1%, 96%, and 96.3%, and 98.9%, 100%, and 99%, respectively. Iomeprol 400 demonstrated an increased arterial enhancement in aortoiliac and femoral districts in comparison to iomeprol 300 (mean increase in opacification, 37.3 Hounsfield units) and a significant better qualitative assessment in the aortoiliac segments without an increase in venous opacification or the presence of venous overlap. No significant differences were found for sensitivity and specificity for the diagnosis of significant stenoses (>70%) and occluded segments. Both agents were well tolerated, and no adverse events were recorded.

Conclusions: The use of a small volume of a high-concentration contrast material yielded higher arterial enhancement from the abdominal aorta down to the femoral arteries with absent or minimal venous overlap and without significant differences in diagnostic ability.