Optimization of sequence parameters in fast MR imaging of the brain with FLASH.
Owing to the intrinsically complex behavior of the signal intensity of fast gradient-refocusing MR sequences, agreement as to the clinically most useful sequence parameters has not yet been reached. This study evaluates the FLASH (fast low-angle shot) sequence for gray-white matter differentiation on normal volunteers at 1.5 T. The FLASH gradient-echo sequence is essentially T1-dependent. For very fast imaging and T1 weighting, the following parameters yield the best results: a flip angle of 30-50 degrees with TR = 20 and TE = 10. To replace T1-weighted SE by the faster FLASH sequence, the best results are achieved by a flip angle of 70-120 degrees with TR = 150-300 and TE = 10 (or shorter, if possible). The most valuable proton-density aspect is achieved by a flip angle of 30 degrees with TR = 300 and TE = 16.
Stadnik
T W
TW
Department of Radiology and Medical Imaging, University Hospital V.U.B., Brussels, Belgium.
Luypaert
R R
RR
Neirynck
E C
EC
Osteaux
M
M
D001921:Brain / Q000473:pathology*; D002540:Cerebral Cortex / Q000473:pathology; D002552:Cerebral Ventricles / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*