Spin-lock field-cycling imaging relaxometry

Spin-lock adiabatic field-cycling imaging (SLOAFI) relaxometry is a novel principle for the fast and convenient record of the dependence of the rotating-frame spin-lattice relaxation time T-1 rho on the effective frequency. A spatial distribution of effective frequencies is produced by adiabatically varying the effective-frequency offset in the presence of a B-o or a B-1 gradient. The spin-locked magnetization relaxes according to the local values of the effective frequency. The profile of the partially relaxed magnetization is imaged using either laboratory-frame (B-1-gradient based) or rotating-frame (B-1-gradient based) imaging. The T-1 rho dispersion can then be evaluated from a series of magnetization profiles recorded while incrementing the relaxation interval. B-0-gradient SLOAFI relaxometry was applied to melts of polydimethylsiloxane. The frequency dependence obtained with conventional techniques could be reproduced. (C) 1995 Academic Press, Inc.