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Accurate MR thermometry by hyperpolarized 129 Xe
Author(s) -
Zhang Le,
Burant Alex,
McCallister Andrew,
Zhao Victor,
Koshlap Karl M.,
Degan Simone,
Antonacci Michael,
Branca Rosa Tamara
Publication year - 2017
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.26506
Subject(s) - chemistry , nuclear magnetic resonance , analytical chemistry (journal) , free induction decay , proton , methylene , magnetic resonance imaging , proton magnetic resonance , resonance (particle physics) , isotopes of xenon , xenon , spin echo , atomic physics , nuclear physics , physics , medicine , organic chemistry , chromatography , radiology
Purpose To investigate the temperature dependence of the resonance frequency of lipid‐dissolved xenon (LDX) and to assess the accuracy of LDX‐based MR thermometry. Methods The chemical shift temperature dependence of water protons, methylene protons, and LDX was measured from samples containing tissues with varying fat contents using a high‐resolution NMR spectrometer. LDX results were then used to acquire relative and absolute temperature maps in vivo and the results were compared with PRF‐based MR thermometry. Results The temperature dependence of proton resonance frequency (PRF) is strongly affected by the specific distribution of water and fat. A redistribution of water and fat compartments can reduce the apparent temperature dependence of the water chemical shift from −0.01 ppm/°C to −0.006 ppm, whereas the LDX chemical shift shows a consistent temperature dependence of −0.21 ppm/°C. The use of the methylene protons resonance frequency as internal reference improves the accuracy of LDX‐based MR thermometry, but degrades that of PRF‐based MR thermometry, as microscopic susceptibility gradients affected lipid and water spins differently. Conclusion The LDX resonance frequency, with its higher temperature dependence, provides more accurate and precise temperature measurements, both in vitro and in vivo. More importantly, the resonance frequency of nearby methylene protons can be used to extract absolute temperature information. Magn Reson Med 78:1070–1079, 2017. © 2016 International Society for Magnetic Resonance in Medicine