A METHOD FOR THE SIMULTANEOUS MEASUREMENT OF NMR SPIN-LATTICE AND SPIN SPIN RELAXATION-TIMES IN COMPARTMENTALIZED SYSTEMS

A method for simultaneous measurement of spin-lattice and spin-spin relaxation times of water in compartmentalized systems is presented. The method is based on a combination of the saturation-recovery and the Carr-Purcell-Meiboom-Gill sequences (SR-CPMG). The result is a two-dimensional data set. The data set can be analyzed in different ways, i.e., in a conventional way yielding the values of T1 and T2 present in the system, or in a way yielding correlated T1 and T2 values for each compartment. The observed relaxation times are the intrinsic relaxation times of the compartments if exchange between the compartments is absent, or additionally affected by exchange, as is demonstrated using two phantoms: (i) two concentric tubes containing nonexchanging MnCl2 solutions of different concentration and (ii) apple fruit tissue, containing water in compartments exhibiting mutual exchange. For (i), the SR-CPMG sequence results in a better S N ratio for the fit of T1 and in the corresponding intrinsic T1 and T2 values of the MnCl2 solutions in each tube. For (ii), the observed relaxation times reflect the exchange kinetics of water between the compartments in addition to the intrinsic T1 and T2 relaxation times in those compartments. © 1992.