title: Regional skeletal muscle measurement: evaluation of new dual-energy X-ray absorptiometry model.
abstract: Although there is growing interest in studying muscle distribution, regional skeletal muscle (SM) mass measurement methods remain limited. The aim of the present study was to develop a new dual-energy X-ray absorptiometry (DEXA) model for estimating regional adipose tissue-free skeletal muscle mass (AT-free SM). Relationships were derived from Reference Man data between tissue-system- level components (i.e., AT-free SM, AT, skeleton, and skin) and molecular-level components including fat-free soft tissue, fat, and bone mineral. The proposed DEXA-SM model was evaluated by multiscan computerized axial tomography (CT). Twenty-seven male subjects [age, 36 +/- 12 (SD) yr; body mass, 73.2 +/- 12.4 kg; 20 were healthy, and 7 had acquired immunodeficiency syndrome] completed DEXA and CT studies. Identical landmarks for DEXA and CT measurements were selected in three regions, including calves, thighs, and forearms. There was a strong correlation for AT-free SM estimates between the new DEXA and CT methods (e.g., sum of three regions, r = 0.86, P < 0.001). Regional AT-free SM measured in the 27 subjects by DEXA and CT, respectively, were 3.44 +/- 0.60 and 3. 47 +/- 0.55 kg (difference 0.9%, P > 0.05) for calves, 10.49 +/- 1. 77 and 10.05 +/- 1.79 kg (difference 4.4%, P < 0.05) for thighs, 1. 36 +/- 0.49 and 1.20 +/- 0.41 kg (difference 13.3%, P < 0.01) for forearms, and 15.29 +/- 2.33 and 14.72 +/- 2.33 kg (difference 3.9%, P < 0.05) for the sum all three regions. Although the suggested DEXA-SM model needs minor refinements, this is a promising in vivo approach for measurement of regional SM, because DEXA is widely available, relatively inexpensive, and radiation exposure is low.
authors.affiliation: Obesity Research Center, St. Luke's-Roosevelt Hospital, Columbia University, College of Physicians and Surgeons, New York, New York 10025, USA.
authors.forename: W
authors.initials: W
authors.lastname: Wang
authors.forename: Z
authors.initials: Z
authors.lastname: Wang
authors.forename: M S
authors.initials: MS
authors.lastname: Faith
authors.forename: D
authors.initials: D
authors.lastname: Kotler
authors.forename: R
authors.initials: R
authors.lastname: Shih
authors.forename: S B
authors.initials: SB
authors.lastname: Heymsfield
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods*; D000273:Adipose Tissue / Q000033:anatomy & histology / Q000502:physiology; D000328:Adult; D000465:Algorithms; D001823:Body Composition / Q000502:physiology*; D015519:Bone Density; D005542:Forearm / Q000502:physiology; D006801:Humans; D007866:Leg / Q000502:physiology; D008297:Male; D008954:Models, Biological; D018482:Muscle, Skeletal / Q000737:chemistry*; D009929:Organ Size / Q000502:physiology; D011237:Predictive Value of Tests; D012867:Skin / Q000033:anatomy & histology / Q000737:chemistry; D012885:Skinfold Thickness; D014057:Tomography, X-Ray Computed