CORRELATED SUSCEPTIBILITY AND DIFFUSION EFFECTS IN NMR MICROSCOPY USING BOTH PHASE-FREQUENCY ENCODING AND PHASE-PHASE ENCODING

NMR microscopy can exhibit contrasts which are characteristic of the l ocal Brownian dynamics, the local susceptibility-related fields, and t he imaging method employed. The influence of susceptibility inhomogene ity and self-diffusion in NMR imaging using both phase-frequency and p hase-phase encoding have been investigated. It is shown both theoretic ally and experimentally that the interplay of susceptibility and self- diffusion in phase-frequency (spin-warp) imaging can lead to bright fe atures which act as a signature for local boundaries. For phase-phase encoding, equations for the point-spread function which arises from bo th susceptibility inhomogeneity and diffusion are derived and it is sh own that phase-phase encoding offers the possibility of overcoming bot h these phenomena, while achieving optimal, sensitivity-limited, resol ution. (C) 1994 Academic Press, Inc.