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Updated: Aug 8, 2025
Quantitative Magnetic Resonance Imaging of Skeletal Muscle Disease
Published on: December 18, 2016
New Insights into the Spread of MRS-Based Water T2 Values Observed in Highly Fatty Replaced Muscles
Harmen Reyngoudt1, Pierre-Yves Baudin1, Pierre G Carlier2
1NMR Laboratory, Neuromuscular Investigation Center, Institute of Myology, Paris, France.
Background:
The reference standard for assessing water T2 (T2,H2O ) at high fat fraction (FF) is 1 H MRS. T2,H2O (T2,H2O,MRS ) dependence on FF (FFMRS ) has recently been demonstrated in muscle at high FF (i.e. ≥60%).
Purpose:
To investigate the relationship between T2,H2O,MRS and FFMRS in the thigh/leg muscles of patients with neuromuscular diseases and to compare with quantitative MRI.
Study Type:
Retrospective case-control study.
Population:
A total of 151 patients with neuromuscular disorders (mean age ± standard deviation = 52.5 ± 22.6 years, 54% male), 44 healthy volunteers (26.5 ± 13.0 years, 57% male).
Field Strength/Sequence:
A 3-T; single-voxel stimulated echo acquisition mode (STEAM) MRS, multispin echo (MSE) imaging (for T2 mapping, T2,H2O,MRI ), three-point Dixon imaging (for FFMRI and mapping).
Assessment:
Mono-exponential and bi-exponential models were fitted to water T2 decay curves to extract T2,H2O,MRS and FFMRS . Water resonance full-width-at-half-maximum (FWHM) and B0 spread (∆B0 ) values were calculated. T2,H2O,MRI (mean), FFMRI (mean, kurtosis, and skewness), and (mean) values were estimated in the MRS voxel.
Statistical Tests:
Mann-Whitney U tests, Kruskal-Wallis tests. A P-value <0.05 was considered statistically significant.
Results:
Normal T2,H2O,MRS threshold was defined as the 90th percentile in healthy controls: 30.3 msec. T2,H2O,MRS was significantly higher in all patients with FFMRS < 60% compared to healthy controls. We discovered two subgroups in patients with FFMRS ≥ 60%: one with T2,H2O,MRS ≥ 30.3 msec and one with T2,H2O,MRS < 30.3 msec including abnormally low T2,H2O,MRS . The latter subgroup had significantly higher water resonance FWHM, ∆B0 , FFMRI kurtosis, and skewness values but nonsignificantly different (P = 1.00) and long T2,H2O,MRS component and its fraction (P > 0.11) based on the bi-exponential analysis.
Data Conclusion:
The findings suggest that the cause for (abnormally) T2,H2O,MRS at high FFMRS is biophysical, due to differences in susceptibility between muscle and fat (increased FWHM and ∆B0 ), rather than pathophysiological such as compartmentation changes, which would be reflected by the bi-exponential analysis.
Evidence Level:
3 TECHNICAL EFFICACY: Stage 3.
