Nonenhanced CT images were acquired in the axial plane using 5-mm collimation. Conventional MRI sequences used in this evaluation included sagittal T1 (time to repeat [TR], 800 milliseconds; echo time [TE], minimum; field of view [FOV], 24 cm; number of excitations [NEX], 1; matrix, 256 × 192; slice thickness, 5 mm; gap, 0 mm), axial fast-spin echo T2-weighted (TR, 4000 milliseconds; effective TE, 85 milliseconds; FOV, 24 cm; NEX, 2; matrix, 256 × 192; slice thickness, 5 mm; gap, 0 mm), and axial fluid attenuated inversion recovery imaging (TR, 8800 milliseconds; TE, 133 milliseconds; inversion time, 2200 milliseconds; FOV, 24 cm; NEX,1; matrix, 256 × 192; slice thickness, 5 mm; gap, 0 mm). Diffusion imaging was performed using a single-shot, multislice, spin-echo, diffusion-weighted echo planar imaging of the whole brain (TR, 10 000 milliseconds; FOV, 24 cm; NEX, 1; matrix, 128 × 128; slice thickness, 5 mm; gap, 0 mm). Four gradient strengths were applied resulting in a b-value of 0 and 1000 mm2/s applied sequentially in the X, Y, and Z gradient directions. Isotropic DWIs and images of the average diffusion coefficient (Dav = Dxx + Dyy + Dzz) were reconstructed. Whole brain MRPI was performed using a multislice gradient-echo scan with the sequence repeated every 2.0 seconds for 60 seconds during the bolus injection of 20 mL of gadolinium-DTPA (Magnevist; Schering-Plough AG, Kenilworth, NJ) injected at a rate of 5 mL/s (TR, 2000 milliseconds; TE, 60 milliseconds; flip angle, 90°; FOV, 24 cm; matrix, 128 × 64; slice thickness, 5 mm; gap, 2.5 mm; axial slices, 17). Injection was via a 20-gauge antecubital intravenous catheter using an MRI-compatible power injector (Spectris; Medrad Inc, Indianola, Pa) with the contrast injection followed by a 20-mL saline flush at a rate of 5 mL per second.per AU. Images of time-to-peak of bolus were calculated on a computer (Sun ULTRA Sparc Workstation; Sun Microsystems Inc, Palo Alto, Calif)using in-house software and viewed using Scion Image software (Scion Corporation, Frederick, Md, 1998).