Related Experiment Video
Updated: Aug 25, 2026
Decellularization-Based Quantification of Skeletal Muscle Fatty Infiltration
Published on: June 9, 2023
In Vivo Assessment of Human Intramyocellular Fatty Acid Composition Using 7 T
Maya Hioki1, Masahiro Umeda2, Yuko Kawai3,4
1Faculty of Health Care and Medical Sports Department of Rehabilitation Physical Therapy Major, Teikyo Heisei University, Ichihara, Chiba, Japan.
None:
Ultra-high-field 7-T 1H-MRS resolves the bis-allylic resonance at 2.8 ppm, a marker present only in fatty acids (FAs) with two or more double bonds, enabling distinction between monounsaturated (MUFA) and polyunsaturated fatty acids (PUFAs) in IMCL that is not achievable at 3 T. The objective of this study was to determine the relative proportions of saturated (SFA), MUFA, and PUFA in IMCL in vivo using 7-T 1H-MRS. To further improve the precision of this fitting, we acquired high-resolution 600-MHz 1H-NMR spectra of representative FA species and incorporated their chemical shifts as prior knowledge in the spectral fitting model. Five predominant FAs-oleic, palmitic, linoleic, and α- and γ-linolenic acids, which together represent the major FA species in human skeletal muscle triglycerides-were analyzed via 600-MHz NMR to determine precise chemical shifts for methyl (-CH3), allylic (-CH2-CH=CH-), and bis-allylic (=CH-CH2-CH=) protons. The NMR spectra revealed distinct shifts: linoleic acid (0.891, 2.044, and 2.782 ppm), oleic acid (0.878 and 2.002 ppm), palmitic acid (0.880 ppm), α-linolenic acid (0.976, 2.064, and 2.807 ppm), and γ-linolenic acid (0.889, 2.074, and 2.808 ppm). These values were subsequently fitted to in vivo 7-T 1H-MRS spectra (range of 0.90-5.55 ppm) acquired from the tibialis anterior of 11 healthy volunteers. Using specialized analysis software, IMCL peaks for methyl (0.90 and 1.00 ppm), allylic (2.02 and 2.06 ppm), and bis-allylic (2.78 and 2.82 ppm) protons were incorporated into the spectral fitting model, enabling improved characterization of FA composition. The mean relative composition of intramyocellular FAs was 36% palmitic acid, 27% oleic acid, and 23% linoleic acid (including α- and γ-linolenic acids). Our findings demonstrate that incorporating NMR-derived prior knowledge enables chemically specific fitting of intramyocellular FA peaks, allowing distinction between SFA, MUFA, and PUFA components within the intramyocellular compartment-information that cannot be obtained from biopsy-based homogenate analysis.
