METHOD FOR IMAGE-BASED MEASUREMENT OF THE REVERSIBLE AND IRREVERSIBLECONTRIBUTION TO THE TRANSVERSE-RELAXATION RATE

A multislice NMR imaging pulse sequence capable of measuring both the reversible and irreversible contribution to the transverse relaxation rate (R(2)' and R(2)) in a single scan is described. The method, terme d GESFIDE (gradient-echo sampling of FID and echo) is based on samplin g the descending and ascending portions of a Hahn echo with a train of gradient echoes. R(2) and R(2)' are computed by exploiting the differ ential evolution of the transverse magnetization before and after the phase-reversal pulse. Salient features of the method are its insensiti vity to RF pulse imperfections and its high precision and efficiency. Applications examined involve the characterization of magnetically inh omogeneous tissues and biomaterials such as trabecular bone marrow in the skeleton and brain iron. (C) 1996 Academic Press, Inc.