Spector E, LeBlanc A, Shackelford L
KRUG Life Sciences, Houston, Texas 77058, USA.
Osteoporos Int. 1995;5(6):440-5. doi: 10.1007/BF01626605.
This study reports on the short-term in vivo precision and absolute measurements of three combinations of whole-body scan modes and analysis software using a Hologic QDR 2000 dual-energy X-ray densitometer. A group of 21 normal, healthy volunteers (11 male and 10 female) were scanned six times, receiving one pencil-beam and one array whole-body scan on three occasions approximately 1 week apart. The following combinations of scan modes and analysis software were used: pencil-beam scans analyzed with Hologic's standard whole-body software (PB scans); the same pencil-beam analyzed with Hologic's newer "enhanced" software (EPB scans); and array scans analyzed with the enhanced software (EA scans). Precision values (% coefficient of variation, %CV) were calculated for whole-body and regional bone mineral content (BMC), bone mineral density (BMD), fat mass, lean mass, %fat and total mass. In general, there was no significant difference among the three scan types with respect to short-term precision of BMD and only slight differences in the precision of BMC. Precision of BMC and BMD for all three scan types was excellent: < 1% CV for whole-body values, with most regional values in the 1%-2% range. Pencil-beam scans demonstrated significantly better soft tissue precision than did array scans. Precision errors for whole-body lean mass were: 0.9% (PB), 1.1% (EPB) and 1.9% (EA). Precision errors for whole-body fat mass were: 1.7% (PB), 2.4% (EPB) and 5.6% (EA). EPB precision errors were slightly higher than PB precision errors for lean, fat and %fat measurements of all regions except the head, although these differences were significant only for the fat and % fat of the arms and legs. In addition EPB precision values exhibited greater individual variability than PB precision values. Finally, absolute values of bone and soft tissue were compared among the three combinations of scan and analysis modes. BMC, BMD, fat mass, %fat and lean mass were significantly different between PB scans and either of the EPB or EA scans. Differences were as large as 20%-25% for certain regional fat and BMD measurements. Additional work may be needed to examine the relative accuracy of the scan mode/software combinations and to identify reasons for the differences in soft tissue precision with the array whole-body scan mode.
本研究报告了使用Hologic QDR 2000双能X线骨密度仪对三种全身扫描模式与分析软件组合进行的短期体内精度和绝对测量。一组21名正常、健康的志愿者（11名男性和10名女性）接受了六次扫描，在大约相隔1周的三个时间段分别进行了一次笔形束和一次阵列全身扫描。使用了以下扫描模式与分析软件的组合：用Hologic标准全身软件分析的笔形束扫描（PB扫描）；用Hologic更新的“增强”软件分析的相同笔形束扫描（EPB扫描）；以及用增强软件分析的阵列扫描（EA扫描）。计算了全身和局部骨矿物质含量（BMC）、骨矿物质密度（BMD）、脂肪量、瘦体重、%脂肪和总体重的精度值（变异系数百分比，%CV）。总体而言，三种扫描类型在BMD的短期精度方面没有显著差异，在BMC的精度方面只有轻微差异。所有三种扫描类型的BMC和BMD精度都非常好：全身值的变异系数<1%，大多数局部值在1%-2%范围内。笔形束扫描显示出比阵列扫描明显更好的软组织精度。全身瘦体重的精度误差分别为：0.9%（PB）、1.1%（EPB）和1.9%（EA）。全身脂肪量的精度误差分别为：1.7%（PB）、2.4%（EPB）和5.6%（EA）。除头部外，在所有区域的瘦体重、脂肪量和%脂肪测量中，EPB的精度误差略高于PB的精度误差，不过这些差异仅在手臂和腿部的脂肪量和%脂肪方面具有显著性。此外，EPB的精度值比PB的精度值表现出更大的个体变异性。最后，比较了三种扫描与分析模式组合之间的骨和软组织绝对值。PB扫描与EPB或EA扫描中的任何一种之间，BMC、BMD、脂肪量、%脂肪和瘦体重均存在显著差异。对于某些局部脂肪和BMD测量，差异高达20%-25%。可能需要进一步开展工作来检验扫描模式/软件组合的相对准确性，并确定阵列全身扫描模式下软组织精度存在差异的原因。
