MEASUREMENT OF INTERNAL CAROTID-ARTERY STENOSIS FROM SOURCE MR ANGIOGRAMS

PURPOSE: To determine whether interpretation of internal carotid arter y (ICA) stenosis from source partitions is more accurate than interpre tation from maximum-intensity projections (MIPs) from three-dimensiona l (3D) time-of-flight (TOF) magnetic resonance (MR) angiography. MATER IALS AND METHODS: The percentage of diameter ICA stenosis was measured on source images and MIPs from sagittal (n = 150) and transverse (n = 140) 3D TOF MR angiography. Measurements were compared with those fro m conventional angiography. RESULTS: Sensitivity and specificity for d istinguishing 70%-99% stenosis were 96% and 78%, respectively, for sag ittal MIPs, 88% and 90% for sagittal source images, 92% and 86% for tr ansverse MIPs, and 92% and 95% for transverse source images. Areas und er the receiver operating characteristic curves statistically signific antly increased (P < .05) with interpretation from source images. Comp lete loss of intravascular signal was not encountered on source partit ions except within a greater than 85% stenosis. CONCLUSION: Interpreta tion of source partitions rather than MIPs reduces the tendency for ov erestimation of stenosis with MR angiography and improves the specific ity for discriminating 70%-99% stenosis.