UNRAVELING DIFFUSION CONSTANTS IN BIOLOGICAL TISSUE BY COMBINING CARR-PURCELL-MEIBOOM-GILL IMAGING AND PULSED-FIELD GRADIENT NMR

A diffusion-weighted multi-spin-echo pulse sequence is presented, whic h allows for simultaneous measurement of T-2, the fractional amplitude , and the diffusion constant of different fractions. Monte Carlo simul ations demonstrate an improvement of this sequence with respect to the accuracy of diffusion constant and fractional amplitude for slow exch ange. Examples are shown for a simple phantom containing two fractions . In addition, experiments on cat brain in healthy condition and follo wing occlusion of the middle cerebral artery show that the fractional amplitude and the diffusion constant of cerebral spinal fluid and norm al brain tissue can be analyzed within each pixel with acceptable accu racy.