 We estimated that a sample of 350 patients including 12 dropout rate would be enrolled to determine an accuracy of VR 3D-TOF-MRA versus VR RDSA as reference standard with a 95 confidence interval of 5 i.e., a standard error of approximately 2.5 above and below the expected VR 3D-TOF-MRA accuracy of 95. A P value of 0.05 was considered to indicate statistical significance. 