Comparison of 3.0- and 1.5-T Three-dimensional Time-of-Flight MR Angiography in Moyamoya Disease: Preliminary Experience

Abstract

Purpose: To prospectively compare 3.0- and 1.5-T three-dimensional (3D) time-of-flight (TOF) magnetic resonance (MR) angiography in patients with moyamoya disease, with special emphasis on the visualization of abnormal netlike vessels (moyamoya vessels). Materials and Methods: Study protocols were approved by the local ethics committee; written informed consent was obtained from all patients. The study included 24 consecutive patients with moyamoya disease (four male and 20 female patients). Patients ranged in age from 17 to 66 years (mean age, 41 years). Moyamoya disease had been diagnosed in all patients before they were entered into the study. All patients underwent 3D TOF MR angiography at both 3.0 and 1.5 T; imaging examinations were performed within 14 days of each other. Maximum intensity projections (MIPs) obtained with MR angiography performed at both 3.0 and 1.5 T were evaluated by two neuroradiologists; the visualization of moyamoya vessels was graded according to a 4-point scale. For both 3.0- and 1.5-T imaging, the number of high-signal-intensity areas and the summation of cross-sectional areas of high signal intensity on source images obtained at the same level of MR angiography were compared quantitatively by using the Wilcoxon matched-pair signed-rank test. Results: Moyamoya vessels were better visualized on MIPs obtained with 3.0-T imaging than on MIPs obtained with 1.5-T imaging (P < .001). At the identical level of the source image, 3.0-T imaging depicted more high-signal-intensity areas than did 1.5-T imaging. Wider cross-sectional areas of moyamoya vessels were visualized with 3.0-T imaging than with 1.5-T imaging (P < .001). Conclusion: Moyamoya vessels are better depicted with MR angiography at 3.0 T than at 1.5 T.