Skeletal muscle involvement in ageing: Exploring the relationship between MRI fat fraction and age in the muscles of the thigh

Motivation: Deposition of fat in skeletal muscle increases with age, leading to reduced muscle quality, but it is currently unclear which muscles are affected first and thus may serve as markers for the onset of this process. Goal(s): To measure intramuscular fat in individual thigh muscles in a healthy ageing cohort. Approach: We applied chemical-shift-based water-fat-separation imaging in 94 participants (median age=56, range=22-89yrs), and proton density fat fraction was calculated for 12 thigh muscles and different muscle groups. Results: We showed age associations with fat deposition in the whole thigh overall (β=0.60, p≪0.001), with associations being stronger in women and in the hamstring muscles. Impact: Understanding the relationship between proton density fat fraction and age in the thigh musculature—particularly in women and in the hamstring muscles—will help clinicians to identify specific muscle targets for interventions designed to reduce functional decline with ageing.