Vokes T J, Giger M L, Chinander M R, Karrison T G, Favus M J, Dixon L B
Department of Medicine, University of Chicago, Chicago, IL, USA.
Osteoporos Int. 2006 Oct;17(10):1472-82. doi: 10.1007/s00198-006-0089-y. Epub 2006 Jul 13.
Bone fragility is determined by bone mass, measured as bone mineral density (BMD), and by trabecular structure, which cannot be easily measured using currently available noninvasive methods. In previous studies, radiographic texture analysis (RTA) performed on the radiographic images of the spine, proximal femur, and os calcis differentiated subjects with and without osteoporotic fractures. The present cross-sectional study was undertaken to determine whether such differentiation could also be made using high-resolution os calcis images obtained on a peripheral densitometer.
In 170 postmenopausal women (42 with and 128 without prevalent vertebral fractures) who had no secondary causes of osteoporosis and were not receiving treatment for osteoporosis, BMD of the lumbar spine, proximal femur, and os calcis was measured using dual energy x-ray absorptiometry. Vertebral fractures were diagnosed on densitometric spine images. RTA, including Fourier-based and fractal analyses, was performed on densitometric images of os calcis.
BMD at all three sites and all texture features was significantly different in subjects with and without fractures, with the most significant differences observed for the femoral neck and total hip measurements and for the RTA feature Minkowski fractal (p<0.001). In univariate logistic regression analysis, Minkowski fractal predicted the presence of vertebral fractures as well as femoral neck BMD (p<0.001). In multivariate logistic regression analysis, both femoral neck BMD and Minkowski fractal yielded significant predictive effects (p=0.001), and when age was added to the model, the effect of RTA remained significant (p=0.002), suggesting that RTA reflects an aspect of bone fragility that is not captured by age or BMD. Finally, when RTA was compared in 42 fracture patients and 42 nonfracture patients matched for age and BMD, the RTA features were significantly different between the groups (p=0.003 to p=0.04), although BMD and age were not.
This study suggests that RTA of densitometer-generated calcaneus images provides an estimate of bone fragility independent of and complementary to BMD measurement and age.
骨脆性由骨量（以骨矿物质密度[BMD]衡量）和小梁结构决定，而小梁结构无法通过目前可用的非侵入性方法轻易测量。在先前的研究中，对脊柱、股骨近端和跟骨的X线图像进行的放射学纹理分析（RTA）能够区分有无骨质疏松性骨折的受试者。本横断面研究旨在确定使用在外周骨密度仪上获得的高分辨率跟骨图像是否也能进行这种区分。
在170名无骨质疏松继发原因且未接受骨质疏松治疗的绝经后女性（42名有椎体骨折史，128名无椎体骨折史）中，使用双能X线吸收法测量腰椎、股骨近端和跟骨的骨密度。在骨密度仪脊柱图像上诊断椎体骨折。对跟骨的骨密度图像进行RTA，包括基于傅里叶变换和分形分析。
有骨折和无骨折的受试者在所有三个部位的骨密度和所有纹理特征均有显著差异，股骨颈和全髋测量以及RTA特征闵可夫斯基分形的差异最为显著（p<0.001）。在单因素逻辑回归分析中，闵可夫斯基分形预测椎体骨折的存在以及股骨颈骨密度（p<0.001）。在多因素逻辑回归分析中，股骨颈骨密度和闵可夫斯基分形均产生显著的预测效果（p=0.001），当将年龄纳入模型时，RTA的效果仍然显著（p=0.002），这表明RTA反映了骨脆性的一个方面，而年龄或骨密度并未体现这一点。最后，在42名骨折患者和42名年龄及骨密度匹配的非骨折患者中比较RTA时，两组之间的RTA特征有显著差异（p=0.003至p=0.04），尽管骨密度和年龄并无差异。
本研究表明，骨密度仪生成的跟骨图像的RTA提供了一种独立于骨密度测量和年龄且与之互补的骨脆性评估方法。
