DIFFUSION MEASUREMENTS IN THE ISCHEMIC HUMAN BRAIN WITH A STEADY-STATE SEQUENCE

RATIONALE AND OBJECTIVES. The authors evaluate the clinical usefulness of a diffusion-weighted steady-state free-precession (SSFP) sequence to detect acute and subacute ischemic changes. METHODS. Twenty-four pa tients were examined on a 1.5-tesla scanner, using a SSFP-sequence (re petition time [TR]/echo time [TE] = 22/3-8 mseconds). The slice thickn ess was 5 mm, 10 averages, 57 seconds per slice, The diffusion gradien t strength was 23 millitesla/m, with b-values from 165 to 598 seconds/ mm(2), Diffusion-weighted images (DWI) were compared with T2-weighted images. RESULTS. The diffusion-weighted SSFP sequence produced diagnos tic quality images in 23 of 24 patients. Diffusion depicted (group 1: 0-12 hours) more acute lesions (3 of 6) than T2-weighted images (2 of 6); the mean lesion diameter depicted by diffusion was 10.9 mm (standa rd deviation [SD], 12.3) and in T2-weighted images was 4.7 mm (SD 6.8) , A significant correlation (P < 0.017) in subacute lesions was found when diffusion was compared with turbo spin echo (mean size difference /T2 = 18.5/17.5 mm, SD 13.2/12.2). CONCLUSIONS. The diffusion-weighted SSFP-sequence is more sensitive in acute ischemia and delineates like wise in subacute ischemia, when compared with T2-weighted imaging.