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Magnetic field dependence of proton spin‐lattice relaxation times
Author(s) -
Korb JeanPierre,
Bryant Robert G.
Publication year - 2002
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.10185
Subject(s) - proton , spin–lattice relaxation , dipole , proton spin crisis , relaxation (psychology) , lattice (music) , condensed matter physics , chemistry , magnetic field , fractal dimension , magnetic dipole–dipole interaction , power law , spin–spin relaxation , nuclear magnetic resonance , physics , fractal , nuclear physics , quantum mechanics , psychology , social psychology , mathematical analysis , statistics , mathematics , organic chemistry , acoustics
The magnetic field dependence of the water‐proton spin‐lattice relaxation rate (1/ T 1 ) in tissues results from magnetic coupling to the protons of the rotationally immobilized components of the tissue. As a consequence, the magnetic field dependence of the water‐proton (1/ T 1 ) is a scaled report of the field dependence of the (1/ T 1 ) rate of the solid components of the tissue. The proton spin‐lattice relaxation rate may be represented generally as a power law: 1/ T 1 ω = Aω − b , where b is usually found to be in the range of 0.5–0.8. We have shown that this power law may arise naturally from localized structural fluctuations along the backbone in biopolymers that modulate the proton dipole‐dipole couplings. The protons in a protein form a spin communication network described by a fractal dimension that is less than the Euclidean dimension. The model proposed accounts quantitatively for the proton spin‐lattice relaxation rates measured in immobilized protein systems at different water contents, and provides a fundamental basis for understanding the parametric dependence of proton spin‐lattice relaxation rates in dynamically heterogeneous systems, such as tissues. Magn Reson Med 48:21–26, 2002. © 2002 Wiley‐Liss, Inc.