In:
Journal of Magnetic Resonance Imaging, Wiley
Abstract:
The reference standard for assessing water T 2 ( T 2,H2O ) at high fat fraction (FF) is 1 H MRS. T 2,H2O ( T 2,H2O,MRS ) dependence on FF (FF MRS ) has recently been demonstrated in muscle at high FF (i.e. ≥60%). Purpose To investigate the relationship between T 2,H2O,MRS and FF MRS 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 T 2 mapping, T 2,H2O,MRI ), three‐point Dixon imaging (for FF MRI and mapping). Assessment Mono‐exponential and bi‐exponential models were fitted to water T 2 decay curves to extract T 2,H2O,MRS and FF MRS . Water resonance full‐width‐at‐half‐maximum (FWHM) and B 0 spread (∆ B 0 ) values were calculated. T 2,H2O,MRI (mean), FF MRI (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 T 2,H2O,MRS threshold was defined as the 90 th percentile in healthy controls: 30.3 msec. T 2,H2O,MRS was significantly higher in all patients with FF MRS 〈 60% compared to healthy controls. We discovered two subgroups in patients with FF MRS ≥ 60%: one with T 2,H2O,MRS ≥ 30.3 msec and one with T 2,H2O,MRS 〈 30.3 msec including abnormally low T 2,H2O,MRS . The latter subgroup had significantly higher water resonance FWHM, ∆ B 0 , FF MRI kurtosis, and skewness values but nonsignificantly different ( P = 1.00) and long T 2,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) T 2,H2O,MRS at high FF MRS is biophysical, due to differences in susceptibility between muscle and fat (increased FWHM and ∆ B 0 ), rather than pathophysiological such as compartmentation changes, which would be reflected by the bi‐exponential analysis. Evidence Level 3 Technical Efficacy Stage 3
Type of Medium:
Online Resource
ISSN:
1053-1807
,
1522-2586
Language:
English
Publisher:
Wiley
Publication Date:
2023
detail.hit.zdb_id:
1497154-9
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