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Magnetic resonance imaging with T 1 dispersion contrast
Author(s) -
Ungersma Sharon E.,
Matter Nathaniel I.,
Hardy Jonathan W.,
Venook Ross D.,
Macovski Albert,
Conolly Steven M.,
Scott Greig C.
Publication year - 2006
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.20910
Subject(s) - nuclear magnetic resonance , dispersion (optics) , relaxation (psychology) , contrast (vision) , field strength , magnetic resonance imaging , magnetization , field (mathematics) , magnetic field , materials science , relaxometry , chemistry , physics , biology , optics , medicine , mathematics , radiology , spin echo , quantum mechanics , neuroscience , pure mathematics
Prepolarized MRI uses pulsed magnetic fields to produce MR images by polarizing the sample at one field strength (∼0.5 T) before imaging at a much lower field (∼50 mT). Contrast reflecting the T 1 of the sample at an intermediate field strength is achieved by polarizing the sample and then allowing the magnetization to decay at a chosen “evolution” field before imaging. For tissues whose T 1 varies with field strength ( T 1 dispersion), the difference between two images collected with different evolution fields yields an image with contrast reflecting the slope of the T 1 dispersion curve between those fields. Tissues with high protein content, such as muscle, exhibit rapid changes in their T 1 dispersion curves at 49 and 65 mT due to cross‐relaxation with nitrogen nuclei in protein backbones. Tissues without protein, such as fat, have fairly constant T 1 over this range; subtracting images with two different evolution fields eliminates signal from flat T 1 dispersion species. T 1 dispersion protein‐content images of the human wrist and foot are presented, showing clear differentiation between muscle and fat. This technique may prove useful for delineating regions of muscle tissue in the extremities of patients with diseases affecting muscle viability, such as diabetic neuropathy, and for visualizing the protein content of tissues in vivo. Magn Reson Med 2006. © 2006 Wiley‐Liss, Inc.