Quality Control , AccuracM and Prediction Capacity of Dual Energy X - ray Absorptiometry Variables and Data Acquisition

The acquisition of soft tissue measurements, fat (chemical) or adipose tissue (morphological) quantitics, is essential in clinical research and nutritional status and its associated health risks, This has led to a proliferation of methods for the in-vivo deterrnination of body composition, None of the indirect in-vivo approaches to estimate body adipose tissue has been validated against direct dissection data except fbr the skinfold. Since the development of DEXA as a measurernent tool of bone density and mineral content fbr the detection of osteoporosis, it became a tool fbr measuring regional and whole body masses, lean tissue, and fat, A number of validation attempts have been made, however mostly against other indirect in-vivo techniques. The purpose of this study was to conduct an in-vitro validation and quality control of the data acquisition ofDEXA using dissection as the criterion method. Fourteen poreine hind legs were scanned with DEXA, weighed in air and water and disseeted into skin, adipose tissue, muscle and bone, Normal distribution, means, standard deviations, paired student t-test, Pearson correlation coeMcients, inteTclass correlations test, and a Btand-Altman plot were used. The results show systematically good to excellent correlations between DEXA and dissection data acquisition (r2=O.75 to O.99), but absolute indirect DEXA and direct dissection values are significantly different (p<O,05). DEXA ovcrestimates total weight, lean mass, and fat free mass and underestimates both mass and % adipose tissue, DEXA provides erroneous values for bone density. Data produced by DEXA are rnorphological, not chemical values, as claimed by the manufacturer. This `pilot' study indicates that a `simple' combination of skin, adipose tissue, muscle, and bone from hind legs may give an incomplete picture of reality as one needs to measure viscera, connective tissue, and air pockets of the body, Validation studies with intact bodies are advised. J PArysiol Anthfiopol 27(bj: 317-323, 2008 http://wwwjstage,jst,go, jptbrowseijpa2 [DOI: 102114ljpa2.27.317]