Background

Assessment of the thigh muscle fat composition using magnetic resonance imaging (MRI) can provide surrogate markers in subjects suffering from various musculoskeletal disorders including knee osteoarthritis or neuromuscular diseases. However, little is known about the relationship with muscle strength. Therefore, we investigated the associations of thigh muscle fat with isometric strength measurements.

Methods

Twenty healthy subjects (10 females; median age 27 years, range 22–41 years) underwent chemical shift encoding-based water-fat MRI, followed by bilateral extraction of the proton density fat fraction (PDFF) and calculation of relative cross-sectional area (relCSA) of quadriceps and ischiocrural muscles. Relative maximum voluntary isometric contraction (relMVIC) in knee extension and flexion was measured with a rotational dynamometer. Correlations between PDFF, relCSA, and relMVIC were evaluated, and multivariate regression was applied to identify significant predictors of muscle strength.

Results

Significant correlations between the PDFF and relMVIC were observed for quadriceps and ischiocrural muscles bilaterally (p = 0.001 to 0.049). PDFF, but not relCSA, was a statistically significant (p = 0.001 to 0.049) predictor of relMVIC in multivariate regression models, except for left-sided relMVIC in extension. In this case, PDFF (p = 0.005) and relCSA (p = 0.015) of quadriceps muscles significantly contributed to the statistical model with R²_adj = 0.548.

Conclusion

Chemical shift encoding-based water-fat MRI could detect changes in muscle composition by quantifying muscular fat that correlates well with both extensor and flexor relMVIC of the thigh. Our results help to initiate early, individualised treatments to maintain or improve muscle function in subjects who do not or not yet show pathological fatty muscle infiltration.

中文翻译：

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大腿肌肉脂肪浸润与基于化学位移编码的水脂磁共振成像的等距强度测量结果的关联。

背景

使用磁共振成像（MRI）对大腿肌肉脂肪成分的评估可以为患有各种肌肉骨骼疾病（包括膝骨关节炎或神经肌肉疾病）的受试者提供替代标记。但是，关于肌肉力量的关系知之甚少。因此，我们调查了大腿肌肉脂肪与等距强度测量的关联。

方法

二十名健康受试者（10名女性；中位年龄27岁，范围22-41岁）接受了基于化学位移编码的水脂肪MRI检查，然后双侧提取质子密度脂肪分数（PDFF）并计算了相对横截面积股四头肌和坐骨肌（relCSA）。用旋转测力计测量膝关节伸展和屈曲的相对最大自愿等距收缩（relMVIC）。评估了PDFF，relCSA和relMVIC之间的相关性，并应用了多元回归来确定肌肉力量的重要预测指标。

结果

观察到双侧股四头肌和坐骨肌PDFF和relMVIC之间存在显着相关性（p  = 0.001至0.049）。PDFF，而不是relCSA， 在多元回归模型中是relMVIC的统计显着性预测指标（p = 0.001至0.049），除了扩展的左侧relMVIC以外。在这种情况下， 股四头肌的PDFF（p  = 0.005）和relCSA（p = 0.015）对R ² _adj  = 0.548的统计模型有显着贡献。

结论

基于化学位移编码的水脂MRI可以通过量化与大腿伸肌和屈肌relMVIC良好相关的肌肉脂肪来检测肌肉组成的变化。我们的结果有助于开始早期个体化治疗，以维持或改善尚未或尚未显示出病理性脂肪肌浸润的受试者的肌肉功能。