Rea J A, Steiger P, Blake G M, Potts E, Smith I G, Fogelman I
Osteoporosis Screening and Research Unit, Guy's Hospital, London, United Kingdom.
J Bone Miner Res. 1998 Mar;13(3):464-74. doi: 10.1359/jbmr.1998.13.3.464.
Vertebral fractures are a common and important consequence of osteoporosis and are often identified via morphometric analysis of conventional lateral spine radiographs (morphometric radiography or MRX). A new method of performing vertebral morphometry using images acquired on dual-energy X-ray absorptiometry (DXA) scanners (morphometric X-ray absorptiometry or MXA) has recently been developed. In this study, we derive reference data for vertebral heights and height ratios using MXA scans as the data source and compare the results with previously published MRX studies. One thousand and nineteen Caucasian women (mean age 63 years, range 33-86) were recruited. An MXA scan, covering 13 vertebrae from L4 to T4, was acquired for each subject on one of four DXA systems located at three centers in the U.K. Analysis of variance found statistically significant but relatively small differences among centers, machines, and scan modes, and therefore data were pooled for reference range calculations. Three vertebral heights (anterior, mid, and posterior) were measured and four ratios (wedge, mid-wedge, and two crush) calculated. These data sets were trimmed using an iterative algorithm to remove extreme values assumed to represent deformed vertebrae, then mean and SD values were calculated using the remaining data. When the data were split by age, a small but statistically significant decrease in vertebral height between the sixth and eighth decades was found, but this was not replicated for the vertebral height ratios. Marked differences were observed between MXA data and MRX, but were comparable to those between different MRX studies. These may result from differences in image quality and point placement protocols, population differences, differences in radiographic technique, and differences in the derivation of a group of "normal" vertebrae. This study suggests that reference data of vertebral dimensions should be specific to the technique which uses those data as a reference, i.e., MXA.
椎体骨折是骨质疏松症常见且重要的后果，通常通过传统脊柱侧位X线片的形态计量分析（形态计量X线摄影或MRX）来识别。最近开发了一种利用双能X线吸收仪（DXA）扫描仪获取的图像进行椎体形态计量的新方法（形态计量X线吸收法或MXA）。在本研究中，我们以MXA扫描作为数据源得出椎体高度和高度比的参考数据，并将结果与先前发表的MRX研究进行比较。招募了1019名白人女性（平均年龄63岁，范围33 - 86岁）。在英国三个中心的四台DXA系统之一上，为每位受试者进行了一次覆盖从L4到T4共13个椎体的MXA扫描。方差分析发现各中心、机器和扫描模式之间存在统计学上显著但相对较小的差异，因此将数据合并以计算参考范围。测量了三个椎体高度（前部、中部和后部）并计算了四个比率（楔形变、中部楔形变和两个压缩比）。使用迭代算法对这些数据集进行修剪，以去除假定代表变形椎体的极值，然后使用剩余数据计算均值和标准差。当按年龄划分数据时，发现第六和第八个十年之间椎体高度有小幅但统计学上显著的下降，但椎体高度比未出现这种情况。观察到MXA数据与MRX之间存在明显差异，但与不同MRX研究之间的差异相当。这些差异可能源于图像质量和点放置方案的不同、人群差异、放射技术差异以及一组“正常”椎体推导过程中的差异。本研究表明，椎体尺寸的参考数据应特定于将这些数据用作参考的技术，即MXA。
