Prediction of degree of carotid stenosis with the transluminal attenuation difference ratio.

We aimed to assess the diagnostic performance of transluminal attenuation difference (TAD) in predicting the severity of internal carotid artery (ICA) stenosis. The study cohort consisted of 48 patients with <50% stenosis, 50%-69% stenosis, 70%-99% stenosis, and 51 controls without plaque development in ICA. A total of 143 measurements were performed through right and left internal and common carotid arteries. The TAD ratio was calculated as the difference between the mean attenuation values of the common carotid artery (CCA) and ICA, divided by the MAV of the CCA, multiplied by 100. TAD ratio was significantly higher in severe (>70%) stenosis compared with control arteries and low-moderate stenosis. A TAD ratio cutoff of 4.5 predicted 70%-99% stenosis with a sensitivity of 100% and specificity of 93%. The inter- and intraobserver agreements in TAD measurements were almost perfect (ICC, 0.89-0.86). Assessment of TAD ratio predicts the degree of stenosis in concordance with NASCET system.