Quantitative Skeletal Muscle MRI: Part 2, MR Spectroscopy and T2 Relaxation Time Mapping—Comparison Between Boys With Duchenne Muscular Dystrophy and Healthy Boys

ObjectiveWe followed up patients with facioscapulohumeral muscular dystrophy (FSHD) with sequential examinations over 2 years to investigate whether inflammatory lesions always precede fat replacement, if inflammation can be resolved without muscle degeneration, and if inflammatory lesions in muscle are always followed by fat replacement.MethodsIn this longitudinal study of 10 sequential MRI assessments over 2.5 years, we included 10 patients with FSHD. We used MRI with short TI inversion recovery to identify regions of interest (ROIs) with hyperintensities indicating muscle inflammation. Muscle T2 relaxation time mapping was used as a quantitative marker of muscle inflammation. Dixon sequences quantified muscle fat replacement. Ten healthy controls were examined with a magnetic resonance scan once for determination of normal values of T2 relaxation time.ResultsWe identified 68 ROIs with T2 elevation in the patients with FSHD. New ROIs with T2 elevation arising during the study had muscle fat content of 6.4% to 33.0% (n = 8) and 47.0% to 78.0% lesions that resolved (n = 6). ROIs with T2 elevation had a higher increase in muscle fat content from visits 1 to 10 (7.9 ± 7.9%) compared to ROIs with normal muscle T2 relaxation times (1.7 ± 2.6%; p < 0.0001). Severe T2 elevations were always followed by an accelerated replacement of muscle by fat.ConclusionsOur results suggest that muscle inflammation starts in mildly affected muscles in FSHD, is related to a faster muscle degradation, and continues until the muscles are completely fat replaced.ClinicalTrials.gov identifierNCT02159612.

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Objective measurement of minimal fat in normal skeletal muscles of healthy children using T2 relaxation time mapping (T2 maps) and MR spectroscopy

Pediatric Radiology ◽

10.1007/s00247-013-2791-1 ◽

2013 ◽

Vol 44 (2) ◽

pp. 149-157 ◽

Cited By ~ 12

Author(s):

Hee Kyung Kim ◽

Suraj Serai ◽

Arnold C. Merrow ◽

Lily Wang ◽

Paul S. Horn ◽

...

Keyword(s):

Relaxation Time ◽

Mr Spectroscopy ◽

Skeletal Muscles ◽

Objective Measurement ◽

Healthy Children ◽

T2 Relaxation Time ◽

T2 Relaxation ◽

Minimal Fat

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A Longitudinal Study of T2 Mapping Combined With Diffusion Tensor Imaging to Quantitatively Evaluate Tissue Repair of Rat Skeletal Muscle After Frostbite

Frontiers in Physiology ◽

10.3389/fphys.2020.597638 ◽

2021 ◽

Vol 11 ◽

Author(s):

Yue Gao ◽

Zhao Lu ◽

Xiaohong Lyu ◽

Qiang Liu ◽

Shinong Pan

Keyword(s):

Skeletal Muscle ◽

Relaxation Time ◽

Diffusion Tensor Imaging ◽

Muscle Injury ◽

Diffusion Tensor ◽

T2 Mapping ◽

Imaging Biomarkers ◽

T2 Relaxation Time ◽

T2 Relaxation ◽

Skeletal Muscle Injury

Purpose: T2 mapping and diffusion tensor imaging (DTI) enable the detection of changes in the skeletal muscle microenvironment. We assessed T2 relaxation times, DTI metrics, performed histological characterization of frostbite-induced skeletal muscle injury and repair, and provided diagnostic imaging biomarkers.Design and Methods: Thirty-six Sprague Dawley rats (200 ± 10 g) were obtained. Thirty rats were used for establishing a skeletal muscle frostbite model, and six were untreated controls. Functional MR sequences were performed on rats on days 0, 3, 5, 10, and 14 (n = 6 per time point). Rats were then sacrificed to obtain the quadriceps muscles. Tensor eigenvalues (λ1, λ2, and λ3), mean diffusivity (MD), fractional anisotropy (FA), and T2 values were compared between the frostbite model and control rats. ImageJ was used to measure the extracellular area fraction (EAF), muscle fiber cross-sectional area (fCSA), and skeletal muscle tumor necrosis factor α (TNF-α), and Myod1 expression. The correlation between the histological and imaging parameters of the frostbitten skeletal muscle was evaluated. Kolmogorov–Smirnoff test, Leven’s test, one-way ANOVA, and Spearman coefficient were used for analysis.Results: T2 relaxation time of frostbitten skeletal muscle was higher at all time points (p < 0.01). T2 relaxation time correlated with EAF, and TNF-α and Myod1 expression (r = 0.42, p < 0.05; r = 0.86, p < 0.01; r = 0.84, p < 0.01). The average tensor metrics (MD, λ1, λ2, and λ3) of skeletal muscle at 3 and 5 days of frostbite increased (p < 0.05), and fCSA correlated with λ1, λ2, and λ3, and MD (r = 0.65, p < 0.01; r = 0.48, p < 0.01; r = 0.52, p < 0.01; r = 0.62, p < 0.01).Conclusion: T2 mapping and DTI imaging detect frostbite-induced skeletal muscle injury early. This combined approach can quantitatively assess skeletal muscle repair and regeneration within 2 weeks of frostbite. Imaging biomarkers for the diagnosis of frostbite were suggested.

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