Added Value of Dual-Energy CT and Low-Attenuation Muscle Quality Measures for Lower-Limb Function in Community-Dwelling Older Adults

Abstract This cross-sectional study examined whether computed tomography (CT)-derived measures of muscle quality, the low-attenuation muscle area (LAMA) ratio and dual-energy CT fat fraction (DECT-FF), were associated with physical function independently of muscle quantity measured by the CT skeletal muscle index (CT-SMI) in older adults. L3-level DECT images were obtained from 58 prospectively enrolled community-dwelling older adults in Fukushima, Japan. We assessed how CT-SMI, the LAMA ratio, and DECT-FF were related to the 30-second chair-stand test (CS-30; n = 50) and grip strength (n = 58). After accounting for age, sex, and CT-SMI, both the LAMA ratio (p = 0.031) and DECT-FF (p = 0.045) were independently associated with CS-30 performance, whereas neither was independently associated with grip strength. CS-30 performance did not differ between the lower and upper quartiles of CT-SMI scores standardized within each sex (p = 0.478), but differed between quartiles when CT-SMI was combined with either the LAMA ratio (p = 0.005) or DECT-FF (p < 0.001). CT-derived muscle quality measures provided information beyond muscle quantity for explaining lower-limb physical function. DECT-FF may be particularly useful when a muscle quality measure less affected by differences between scanners is needed.