Affiliation:
1. Norwich Medical School University of East Anglia Norwich UK
2. C.J. Gorter MRI Center, Department of Radiology Leiden University Medical Center Leiden The Netherlands
3. Translational Gerontology Branch, Intramural Research Program, National Institute on Aging National Institutes of Health Baltimore Maryland USA
4. Emory University School of Medicine Atlanta Georgia USA
5. Department of Radiology and Radiological Sciences, Vanderbilt University Institute of Imaging Science Vanderbilt University Medical Center Tennessee Nashville USA
6. Laboratory of Clinical Investigation, Intramural Research Program, National Institute on Aging National Institutes of Health Baltimore Maryland USA
7. Department of Neurology University of Maryland School of Medicine Baltimore Maryland USA
Abstract
AbstractDiffusion‐tensor magnetic resonance imaging (DT‐MRI) offers objective measures of muscle characteristics, providing insights into age‐related changes. We used DT‐MRI to probe skeletal muscle microstructure and architecture in a large healthy‐aging cohort, with the aim of characterizing age‐related differences and comparing these to muscle strength. We recruited 94 participants (43 female; median age = 56, range = 22–89 years) and measured microstructure parameters—fractional anisotropy (FA) and mean diffusivity (MD)—in 12 thigh muscles, and architecture parameters—pennation angle, fascicle length, fiber curvature, and physiological cross‐sectional area (PCSA)—in the rectus femoris (RF) and biceps femoris longus (BFL). Knee extension and flexion torques were also measured for comparison to architecture measures. FA and MD were associated with age (β = 0.33, p = 0.001, R2 = 0.10; and β = −0.36, p < 0.001, R2 = 0.12), and FA was negatively associated with Type I fiber proportions from the literature (β = −0.70, p = 0.024, and R2 = 0.43). Pennation angle, fiber curvature, fascicle length, and PCSA were associated with age in the RF (β = −0.22, 0.26, −0.23, and −0.31, respectively; p < 0.05), while in the BFL only curvature and fascicle length were associated with age (β = 0.36, and −0.40, respectively; p < 0.001). In the RF, pennation angle and PCSA were associated with strength (β = 0.29, and 0.46, respectively; p < 0.01); in the BFL, only PCSA was associated with strength (β = 0.43; p < 0.001). Our results show skeletal muscle architectural changes with aging and intermuscular differences in the microstructure. DT‐MRI may prove useful for elucidating muscle changes in the early stages of sarcopenia and monitoring interventions aimed at preventing age‐associated microstructural changes in muscle that lead to functional impairment.