Nowitz Michael, Monahan Paula
Pacific Radiology, Wakefield Hospital, Newtown, Wellington, New Zealand.
Department of Medicine, University of Otago, Wellington, New Zealand.
J Med Imaging Radiat Oncol. 2018 Apr;62(2):179-182. doi: 10.1111/1754-9485.12646. Epub 2017 Jul 29.
Dual-energy X-ray absorptiometry (DXA) is increasingly being used to assess abnormalities in body composition associated with a wide variety of conditions including obesity, sarcopenia, diabetes, anorexia, human immunodeficiency virus lipodystrophy, malabsorption and neuromuscular disorders The objective of this study was to determine the short-term in vivo precision and least significant change in serial body composition measurements provided by the Hologic Horizon A densitometer as there is no published, peer reviewed body composition precision data on Horizon scanners in the medical literature.
After acquiring two new Hologic Horizon A densitometers, short term precision scanning was performed on the two scanners using different groups of 30 volunteers, who had duplicate scans with all scans performed by the same operator. Using the International Society of Clinical Densitometry's advanced precision tool, the scan data were recorded and the coefficient of variation (CV) and least significant change (LSC) determined for total fat, lean and bone mineral content (BMC) and bone mineral density (BMD).
Coefficients of variation of 0.78% and 0.77% were achieved for total fat (LSC at 95% confidence 2.15%) and 0.52% and 0.40% for total lean (LSC at 95% confidence 1.45% and 1.11%).
These results indicate that the two Horizon A scanners in this study exceeded the minimum acceptable precision values by roughly a factor of four and are therefore capable of detecting small differences in lean and fat mass of 1-2% between two measurements at 95% confidence.
双能X线吸收法（DXA）越来越多地用于评估与多种病症相关的身体成分异常，这些病症包括肥胖症、肌肉减少症、糖尿病、厌食症、人类免疫缺陷病毒脂肪代谢障碍、吸收不良和神经肌肉疾病。本研究的目的是确定Hologic Horizon A骨密度仪提供的系列身体成分测量的短期体内精密度和最小显著变化，因为医学文献中没有关于Horizon扫描仪的已发表的、经过同行评审的身体成分精密度数据。
购置两台新的Hologic Horizon A骨密度仪后，使用不同组的30名志愿者在两台扫描仪上进行短期精密度扫描，所有扫描均由同一操作员进行重复扫描。使用国际临床骨密度测量学会的高级精密度工具，记录扫描数据，并确定总脂肪、瘦体重、骨矿物质含量（BMC）和骨矿物质密度（BMD）的变异系数（CV）和最小显著变化（LSC）。
总脂肪的变异系数分别为0.78%和0.77%（95%置信度下的LSC为2.15%），总瘦体重的变异系数分别为0.52%和0.40%（95%置信度下的LSC为1.45%和1.11%）。
这些结果表明，本研究中的两台Horizon A扫描仪的精密度超出了可接受的最低精密度值约四倍，因此能够在95%置信度下检测出两次测量之间1-2%的瘦体重和脂肪量的微小差异。
