Skeletal muscle mass: evaluation of neutron activation and dual
energy x-ray absorptiometry methods by computerized tomography.
Wang, Zi-Mian, Marjolein Visser, Ruimei Ma, Richard N. Baumgartner,
Donald Kotler, Dympna Gallagher, Steven B. Heymsfield.
Obesity Research Center, St. Luke's-Roosevelt Hospital, Columbia
University, College of Physicians and Surgeons, New York, N.Y.;
Department of Human Nutrition, Wageningen Agricultural University,
Wageningen, The Netherlands; Medical Department, Brookhaven National
Laboratory, Upton, N.Y.; Clinical Nutrition Laboratory, University of
New Mexico School of Medicine, Albuquerque, N.M.
APStracts 2:0463A, 1995.
Although skeletal muscle (SM) is a major body composition component,
whole body measurement methods remain limited and inadequately
investigated. The aim of the present study was to evaluate the
Burkinshaw in vivo neutron-activation analysis-whole body 40K
counting (IVNA) and dual energy X-ray absorptiometry (DXA) methods of
estimating SM by comparison to adipose tissue-free SM measured using
multiscan computerized axial tomography (CT). In the Burkinshaw
method the potassium to nitrogen ratio of SM and non-SM lean are
assumed constant; in the DXA method the ratio of appendicular SM to
total SM is assumed constant at 0.75. Seventeen healthy men (body
weight, X +/- SD, 77.5 +/- 13.8 kg) and 8 men with AIDS (65.5 +/- 7.6
kg) completed CT, IVNA, and DXA studies. SM measured by CT was 34.4
+/- 6.2 kg for the healthy subjects and 27.2 +/- 4.0 kg for the AIDS
patients. Compared with CT, the Burkinshaw method underestimated SM
by an average of 6.9 kg (20.1%, p = 0.0001) and 6.3 kg (23.2%, p =
0.01) in the healthy men and men with AIDS, respectively. The DXA
method minimally overestimated SM in both groups (2.0 kg and 5.8% in
healthy men, p = 0.001; 1.4 kg and 5.1% in men with AIDS, p = 0.16).
This overestimate could be explained by a higher actual than assumed
ratio of DXA-measured appendicular SM to total body SM (actual = 0.79
+/- 0.05, and assumed = 0.75). The current study results reveal that
large errors are present in the Burkinshaw SM method and that
substantial refinements in the models that form the basis of this
IVNA approach are needed. The model upon which the DXA-SM method is
based also needs further minor refinements, but this is a promising
in vivo approach because of less radiation exposure and lower cost
than with IVNA and CT.
Received 27 December 1994; accepted in final form 3 October 1995.
APS Manuscript Number A1343-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95