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PURPOSE: To assess the proton T1 and T2 relaxation of in vivo hepatic water, choline and lipid resonances with possible J-coupling behavior of lipids in healthy volunteers at 7 Tesla (T). MATERIALS AND METHODS: Relaxation measurements were conducted on corn oil phantoms and on the hepatic tissue of 11 healthy volunteers at 7 T using a surface coil and a STEAM sequence. T1 's were determined by monoexponential fitting, and T2 's by both monoexponential and enhanced-exponential fitting (empirically designed to consider J-coupling of lipid resonances). RESULTS: In vivo T1 's at 7 T were estimated as follows: water (4.70 ppm), 1362 ± 83 ms; methyl- (0.90 ppm), 1026 ± 162 ms; methylene- (1.30 ppm), 514 ± 25 ms; α-olefinic- (2.02 ppm), 488 ± 220 ms; α-carboxyl- (2.24 ppm), 476 ± 89 ms; diacyl- (2.77 ppm), 479 ± 260 ms group of lipid chains; and choline compounds (3.22 ppm), 1084 ± 52 ms. The T2 's calculated with enhanced fitting were as follows: water, 15 ± 2 ms; methyl-, 34 ± 10 ms; methylene-, 41 ± 8 ms; α-olefinic-, 44 ± 19 ms; α-carboxyl-, 39 ± 15 ms; diacyl-, 44 ± 5 ms group of lipid chains; and choline compounds, 32 ± 9 ms. CONCLUSION: An accurate knowledge of in vivo relaxation and J-coupling behavior will significantly improve the quantification of an extended number of resolved liver metabolites at 7 T.

Original publication

DOI

10.1002/jmri.24489

Type

Journal article

Journal

J Magn Reson Imaging

Publication Date

12/2014

Volume

40

Pages

1365 - 1374

Keywords

7 T, J-coupling, STEAM, hepatic lipids, magnetic resonance spectroscopy, relaxation times, Adult, Body Water, Choline, Female, Humans, Lipids, Liver, Magnetic Resonance Imaging, Male, Proton Magnetic Resonance Spectroscopy, Reference Values, Reproducibility of Results, Sensitivity and Specificity, Tissue Distribution