Belinda Brown

Background: Sarcopenia, an age-related loss of skeletal muscle strength, mass and physical performance, is associated with adverse outcomes. Temporalis muscle thickness (TMT), obtained on brain magnetic resonance imaging (MRI), has been proposed as a sarcopenia biomarker. We aimed to determine if TMT correlates with appendicular skeletal muscle mass (ASM) via dual-energy X-ray absorptiometry (DXA), a guideline-recommended test to diagnose sarcopenia, and could be used to assess for sarcopenia.

Methods: Retrospective study of healthy older adults in the Intense Physical Activity and Cognition study, in whom MRI and DXA obtained on the same visit were analysed. TMT was measured on axial T1-weighted MRIs bilaterally, and average TMT used for analysis. ASM was adjusted for body size (height2). Sarcopenia was defined as ASM <7.0 kg/m2 for males and <5.5 kg/m2 for females as per the 2019 European working group on sarcopenia in older people criteria (1). Pearson correlation assessed the relationship between TMT and ASM or age.

Results: There were 95 participants (mean±standard deviation [SD] age 69.1 ± 5.2 years, 53% female, 11% had sarcopenia). The mean±SD ASM was 7.0 ± 1.2 kg/m2 and TMT was 7.3 ± 1.2 mm. TMT and ASM were moderately correlated (r = 0.41, 95% confidence interval 0.23–0.56). TMT did not correlate with age but differed significantly between those with (mean ± SD 7.4 ± 1.2) and without sarcopenia (mean ± SD 6.2 ± 0.8, p = 0.004).

Conclusion: Among a cohort of healthy older adults, TMT demonstrated moderate correlation with ASM. Future studies could explore the relationship between TMT and long-term clinical and functional outcomes, and whether TMT could identify people for interventional trials.