1 /T1p and Low‐Field 1 / T1 of Tissue Water Protons Arise from Magnetization Transfer to Macromolecular Solid‐State Broadened Lines
Abstract
We argue that, for solutions of immobilized protein and for tissue, the dependence of 1 / T1 of solvent protons on B0 at low fields and 1 / T1p on B1 for all B0 are both manifestations of the same underlying phenomena: magnetization transfer between mobile water protons and solid‐state broadened protein proton levels. Broadening causes rapid mixing of spin orientation within the transverse plane, at all B0, unless B1 is greater than the protein internal field; this affects 1 / T1p of solvent protons by magnetization transfer. Similarly, decreasing B0 below the internal field mixes all orientations of magnetization, which affects the solvent proton low‐field 1 / T1 and high‐field 1 / T2.© 1992 Academic Press,Inc. Copyright © 1992 Wiley‐Liss, Inc., A Wiley Company