Measuring leg muscle and fat mass in humans: comparison of CT and dual-energy X-ray absorptiometry

Date: 
01-01-2000

Measuring leg muscle and fat mass in humans: comparison of
CT and dual-energy X-ray absorptiometry. J. Appl. Physiol.
88: 452–456, 2000.—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 (r2 5 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 r2 5 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.

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Authors: 
JAMES A. LEVINE, LANA ABBOUD, MITCHEL BARRY, JUDD E. REED, PATRICK F. SHEEDY, AND MICHAEL D. JENSEN