Magnetization transfer contrast (MTC) and tissue water proton relaxation <i>in vivo</i>

TLDR

The study aimed to observe exchange between free and restricted water proton pools in vivo using NMR saturation transfer. This was achieved by applying radiofrequency irradiation to the restricted pool and measuring changes in free pool magnetization and relaxation. The exchange caused a decrease in free pool magnetization and relaxation times, with rate constants of ~1 s⁻¹ in kidney and ~3 s⁻¹ in skeletal muscle, and produced tissue‑specific contrast that appears to be a major determinant of water relaxation properties in vivo. © 1989 Academic Press, Inc.

Abstract

Abstract In this study the exchange between 1 H magnetization in “free” water ( 1 H f ) and that in a pool with restricted motion ( 1 H r ) was observed in tissues in vivo using NMR saturation transfer methods. Exchange between these two pools was demonstrated by a decrease in the steady‐state magnetization and relaxation times of 1 H f with radiofrequency irradiation of 1 H r . The pseudo‐first‐order rate constant for the movement of magnetization from 1 H f to 1 H r was ∼ Is −1 in kidney and ∼3s −1 in skeletal muscle in vivo . Proton NMR imaging demonstrated that this exchange was tissue specific and generated a novel form of NMR image contrast. The extent of exchange between 1 H f and 1 H r as well as the topological correlation ofthe exchange with relaxation weighted images suggests that this pathway is a major determinant of the observed relaxation properties of water 1 H in vivo . © 1989 Academic Press. Inc.