Body composition by DEXA in older adults: accuracy and influence of scan mode

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Abstract
Dual energy x-ray absorptiometry (DEXA) measures bone mineral content(BMC), bone mineral density (BMD), fat-free mass (FFM), and provides estimates of percent body fat. Changes in scan mode geometry (pencil beam vs array) may impact these measures and body composition estimates using multi-compartment models. Forty-one adults, ages 59-79 yr, were scanned in each mode and also underwent hydrostatic weighing and measurement of total body water (tritiated water dilution). The effect of scan mode on measurement of DEXA BMC, BMD, FFM, and percent body fat (DEXA%Fat) was examined. The effect of scan mode on percentage body fat determined by a 4-compartment body composition model (4 Comp%Fat) and comparison of DEXA%Fat and 4 Comp%Fat were also examined. BMC and DEXA%Fat were greater (1.3% and 3.9%, respectively, P P