MR PERFUSION STUDIES WITH T-1-WEIGHTED ECHO-PLANAR IMAGING

The T-1 perfusion model has worked well in brain functional studies wh ere flow changes are measured, Using selective and nonselective invers ion pulses, a new method has been developed to study steady-state brai n blood flow, The authors obtained flow-sensitive images using selecti ve inversion and flow-insensitive images using nonselective inversion, Subtraction of flow-insensitive images from few-sensitive images gave us flow-weighted images with good gray-white flow contrast in cortica l gray matter as well as in the thalamus and basal ganglia. Fitting T( 1)s of flow-insensitive and flow-sensitive images allowed us to obtain preliminary results of brain blood flow maps, Two specific problems c an seriously affect the accuracy of the brain blood flow values and th e gray-white flow contrast of brain blood flow maps, These are the pro blems of the partial volume effect of CSF and gray matter, and the dif ference between blood T-1, and white matter T-1. The authors discuss i n detail the character of these problems and present a number of appro aches to manage such problems.