Differential Diagnosis of Chronic Total Occlusive and Subtotal Occlusive Disease of the Lower Extremity Arteries Using Reverse Attenuation Gradient Sign on CT Angiography

Abstract

OBJECTIVE. The purpose of this study is to evaluate the diagnostic usefulness of the reverse attenuation gradient sign in occlusive lower extremity arterial disease through CT angiography (CTA). MATERIALS AND METHODS. This study sample enrolled 45 men and eight women in the chronic total occlusion group and 30 men and seven women in the subtotal occlusion group. Luminal CT attenuation (in Hounsfield units) was measured at three points from the end of the occlusion site to the first collateral vessel's insertion point. We also used Hounsfield units to measure the CT attenuation of the opposite side artery at the same level in a similar manner. We compared each value using the Mann-Whitney U test. RESULTS. The absolute value of the mean differences in the Hounsfield units among the proximal, middle, and distal portion of chronic total occlusions were higher than those of subtotal occlusions, and this result was statistically significant (p < 0.001). The mean ratios of the Hounsfield units (Hounsfield units of the stenosed lumen divided by Hounsfield units of the opposite normal lumen) of the proximal portion of chronic total occlusions were statistically significantly lower than those of subtotal occlusions. CONCLUSION. The reverse attenuation gradient sign can be applied to the lower extremity arteries and can be helpful for differential diagnosis of chronic total occlusions from subtotal occlusions using CTA.