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Proton relaxation enhancement
Author(s) -
Wood Michael L.,
Hardy Peter A.
Publication year - 1993
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.1880030127
Subject(s) - paramagnetism , superparamagnetism , diamagnetism , relaxation (psychology) , larmor precession , relaxometry , dipole , nuclear magnetic resonance , condensed matter physics , proton , magnetic moment , moment (physics) , magnetic dipole , contrast (vision) , magnetization , mri contrast agent , physics , materials science , magnetic resonance imaging , magnetic field , spin echo , nanotechnology , medicine , nuclear physics , quantum mechanics , radiology , nanoparticle , optics
Paramagnetic and superparamagnetic substances are used as contrast agents to enhance proton relaxation in magnetic resonance imaging. This review summarizes the physics of contrast agents, specifically the mechanisms by which contrast agents enhance T1 and T2 relaxation. The purpose is to provide a background for understanding the behavior of existing contrast agents in basic experimental and clinical studies. Terms such as magnetic dipole, dipole moment, magnetic susceptibility, diamag‐netism, paramagnetism, superparamagnetism, and ferro‐magnetism are introduced. Two important interactions between the magnetic dipole moments of paramagnetic substances and the dipole moments associated with protons are described. The Solomon‐Bloembergen‐Morgan equations and other basic relaxation theory that has been confirmed experimentally are introduced to account for the dependence of relaxation on such parameters as the Larmor frequency, magnetic moment, accessibility of water molecules to the core of a contrast agent, and frequency of molecular motions.