大鼠活体骨量测量质控的影响因素分析

Analysis of quality control of rat bone mass measurement in vivo

目的:探讨双能X线骨密度仪测量活体大鼠骨量时鼠龄、测量部位、扫描方式对测量精确度、准确度的影响。方法:雌性SD大鼠60只,从3月龄开始定期采用双能X线骨密度仪进行骨量测量,对两次扫描之间的变异进行计算分析。于不同月龄处死大鼠,对腰椎灰重与骨矿含量进行回归分析。结果:全身骨密度测量的精确度与月龄无明显相关,3-24月龄内变异系数均<1%;腰椎骨密度测量精确度随月龄增加明显改善,周围骨扫描方式优于全身扫描方式;各月龄两种扫描方式的腰椎骨矿含量与灰重之间均具有良好的相关性,3月龄测量值与真值的差异度高于12及24月龄。结论:双能X线测量活体大鼠骨密度时,鼠龄、测量部位、扫描方式对测量的精确性和准确性均有影响。

Objective： To evaluate the influence of age, measurement site and scan style on the precision and accuracy of rat bone mass measurement in vivo with dual energy X-ray absorptiometry （ DEXA ）. Methods ： Bone mass measurement had been performed on 60 virgin female Sprague-Dawley rats since they were 3 months old. Total body BMD and lumbar vertebrae （L2-5） BMD were measured under two scan styles： total body scan and appendicular scan. Repeated measurement was performed and coefficient of variation （CV） was determined. 20 rats were sacrificed at the age of 3, 12 and 24 months and the ash weight of 2-5 lumbar vertebrae was measured. The correlation and regression analysis was thus done between ash weight and bone mineral content （BMC）. Results： 1. The precision of total body BMD measurement was kept below the level of 1% during 3-24 months of age and was not influenced by age; 2. Lumbar vertebrae BMD was also analyzable from the image of total body scan, and the precision improved significantly with age from 12 months（2.22% -3.36% ） ; 3. Under appendicular scan, the precision of lumbar vertebrae BMD measurement improved with age after 12 months and was significantly higher than that under total body scan （1.55 % -1.8%, P 〈 0.05 ） ; 4. Lumbar vertebrae （2-5） BMC were well correlated with ash weight at all ages and under both scan styles, but the variant at the age of 3 months was higher than that at the age of 12 and 24 months. Conclusion： Animal age, measurement site and scan style all influence the precision and accuracy of rat bone mass measurement in vivo with dual-en- ergy X-ray absorptiometry.