MR data acquisition and transfer:

The MR data were obtained by a 1.5 Tesla MR unit (Signa; GE Medical Systems, Milwaukee, WI). A series of 124 images of post-contrast, 3D SPGR (SPoiled Gradient Recalled acquisition in the steady-state, 1.5 mm thickness, 256x256 matrix of 220-240 mm FOV) were obtained. An MR angiogram in either the axial or the sagittal plane for 3D reconstruction of the vasculature was used. The velocity encoding (VENC) was chosen according to the specific pathology. For cortical/subcortical tumors, we chose 20 cm/sec VENC to visualize small cortical vessels. For arterial information, we used 60 cm/sec. The data were digitally transferred to the workstation (SPARC 20; Sun Microsystems, Inc., Mountain View, CA) via a computer network.