Submitted to: Journal of the American College of Nutrition
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/1/2004
Publication Date: 12/1/2004
Citation: Koo, W.W., Hammami, M., Shypailo, R.J., Ellis, K.J. 2004. Bone and body composition measurements of small subjects: discrepancies from software for fan-beam dual energy x-ray absorptiometry. Journal of the American College of Nutrition. 23(6):647-650. Interpretive Summary: There is increasing evident that the pattern of human growth during early infancy can influence health outcomes as adults. To better understand the changes in bone, muscle and body fat in infancy, the measurements must be precise and accurate. We have tested the performance of the commercial software for an instrument, called a dual-energy x-ray absorptiometer (DXA), using small piglets to approximate the body sizes of infants. We determined that major inaccuracies for bone mineral and body composition measurements were obtained when this software was used.
Technical Abstract: A piglet model was used to determine the variations in measurements from different software algorithms used in the same type of dual energy X ray absorptiometry (DXA) instruments from the same manufacturer. Forty-one piglets (6190 +/- 5856g, mean +/- SD) were scanned in duplicate with a fan-beam densitometer (Hologic QDR4500A, Hologic Inc, Bedford, MA) in the infant whole body scan mode. The same scans were analyzed with two software versions: vKH6 (validated with carcass chemical measurement) and v11.2 (commercial software from the same densitometer manufacturer). All analysis values were highly correlated (r = 0.90 to 1.00) and DXA values for total weights were almost identical. However, v11.2 results consistently overestimated bone mineral content (49.3 +/- 23.4%, mean +/- SD), bone area (21.1 +/- 8.2%), bone mineral density (24.1 +/- 22.2%), and fat mass (160.9 +/- 71.7%) but underestimated lean mass (-14.3 +/- 5.5%) when compared to the values from vKH6. Differences between software versions increased with heavier piglets. The commercial software for fan-beam DXA measurement of piglets, matched for the size of human infants and young children, has major inaccuracies for bone mineral and body composition that become further exaggerated with increasing weight of the subject.