ACCURACY OF MEASUREMENTS OF BODY-COMPOSITION BY DUAL-ENERGY X-RAY ABSORPTIOMETRY INVIVO

The accuracy of body-composition measurements in vivo by dual-energy x -ray absorptiometry (DEXA) was assessed in seven pigs (weight: 35-95 k g) by measurement by DEXA in vivo and chemical analysis after postmort em homogenization. The regression lines between these measurements wer e not significantly different from the line of identity (P > 0.05), th e r values were > 0.97, and the corresponding SEEs were 2.9%, 1.9 kg, and 2.7 kg for percent fat, fat tissue mass, and lean body mass, respe ctively. Changes in fat and lean tissue mass (simulated by placing 8.8 kg porcine lard on the trunk of six women) were accurately measured b y DEXA. The measured total-body bone mineral (TBBM) was significantly affected by the lard (P < 0.05). In conclusion, DEXA is an accurate me thod for measurement of soft-tissue body composition. TBBM measurement s in longitudinal studies may, however, be difficult to interpret if c onsiderable change in soft-tissue composition has occurred.