Dual-energy x-ray absorptiometry body composition model: review of
physical concepts.
Pietrobelli, Angelo, Carmelo Formica, Zimian Wang, Steven B.
Heymsfield.
Obesity Research Center, St. Luke's/Roosevelt Hospital, Columbia
University, College of Physicians & Surgeons, New York, NY
APStracts 3:0191E, 1996.
Although dual-energy x-ray absorptiometry (DXA) is widely used in
clinical research as a means of quantifying body composition, there
remains at present little published information that reviews the
method's underlying physical basis. As a clear understanding of DXA
physical concepts is integral to appropriate use and interpretation,
we present here a three-section review that includes both relevant in
vitro and in vivo experimental demonstrations. In the first section
we describe the main physical principals upon which DXA is based. The
section that follows presents a step-by-step analysis of the DXA two
-component soft tissue model. In the final section we demonstrate how
knowledge of physical concepts can lead to resolution of important
methodological concerns such as the influence of hydration changes on
DXA fat estimates. A thorough understanding of DXA physical concepts
provides a basis for appropriate interpretation of measurement
results and stimulates many new and important research questions.
Received 5 June 1996; accepted in final form 26 August 1996.
APS Manuscript Number E281-6.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 19 September 1996