Reliability and validity of noninvasive imaging of internal carotid artery pseudo-occlusion

Our study evaluated noninvasive tests for the diagnosis of atheromatous internal carotid artery (ICA) pseudo-occlusion. Twenty patients (17 men, 3 women; mean age +/-SD, 64.3+/-11.6 years) with angiographically proven atheromatous ICA pseudo-occlusion (20 vessels) were prospectively examined with MR angiography (MRA; 2D and 3D time-of-flight techniques), color Doppler-assisted duplex imaging (CDDI) and power-flow imaging (PFI) with and without an intravenous ultrasonic contrast agent. As a control group, 13 patients (13 men; mean+/-SD age, 63.0+/-9.0 years) with angiographically proven ICA occlusion (13 vessels) were studied with the same techniques. For the determination of interobserver agreement (kappa statistics), the findings of each diagnostic technique were read by 2 blinded and independent observers who were not involved in patient recruitment and initial data acquisition. Specificity and sensitivity were calculated for all noninvasive techniques (observer consensus) in comparison to the standard of reference (intra-arterial angiography). Interobserver reliabilities were kappa=0.86 for intra-arterial angiography, kappa=0.90 for unenhanced CDDI, kappa=0. 93 for enhanced CDDI, kappa=0.93 for unenhanced PFI, kappa=1.0 for enhanced PFI, kappa=0.93 for 2D MRA, and kappa=0.77 for 3D MRA, respectively (P