title: Measuring leg muscle and fat mass in humans: comparison of CT and dual-energy X-ray absorptiometry.
abstract: Dual-energy X-ray absorptiometry (DEXA) is reported to be inferior to computed tomography (CT) to measure changes in appendicular soft tissue composition. We compared CT- and DEXA-measured thigh muscle and fat mass to evaluate the random and systematic discrepancies between these two methods. Thigh skeletal muscle area (single-slice CT) was suboptimally (r(2) = 0.74, P < 0.0001) related to DEXA-measured thigh fat-free mass (FFM). In contrast, thigh muscle and adipose tissue volumes (multislice CT) were highly related to DEXA-measured thigh FFM and fat (both r(2) = 0.96, P < 0.0001). DEXA-measured leg fat was significantly less than multislice-CT-measured leg adipose tissue volume, whereas multislice-CT-measured leg muscle mass was less (P < 0.0001) than DEXA-measured leg FFM. The systematic discrepancies between the two approaches were consistent with the 10-15% nonfat components of adipose tissue. In conclusion, CT and DEXA measures of appendicular soft tissue are highly related. Systematic differences between DEXA and CT likely relate to the underlying principles of the techniques.
authors.affiliation: Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota 55905, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Levine
authors.forename: L
authors.initials: L
authors.lastname: Abboud
authors.forename: M
authors.initials: M
authors.lastname: Barry
authors.forename: J E
authors.initials: JE
authors.lastname: Reed
authors.forename: P F
authors.initials: PF
authors.lastname: Sheedy
authors.forename: M D
authors.initials: MD
authors.lastname: Jensen
mesh_terms: D015502:Absorptiometry, Photon; D000273:Adipose Tissue / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000502:physiology; D000328:Adult; D005260:Female; D006801:Humans; D007866:Leg / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000502:physiology; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology*; D012044:Regression Analysis; D013848:Thigh / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology