基于体素的股骨近端骨密度和骨皮质厚度的测量及可重复性研究

目的研究基于定量CT(quantitative computed tomography,QCT)的股骨近段骨密度和骨皮质厚度体素化测量的可重复性,为髋部骨折研究提供技术支持。方法选择28例短时间内QCT扫描两次的髋部骨折患者,其中男性6例,女性22例。从QCT影像中手动分割出股骨近段结构。借助体素形态学分析(voxel-based morphometry,VBM)思想,选择一个形状和结构适中的股骨近段结构作为标准模板,通过三维弹性配准算法将其他股骨近段映射到标准模板上。采用最小二乘和列文伯格-马夸尔特(Levenberg-Marquardt)方法将CT值转化成体素化的骨密度和骨皮质厚度值。最后,使用统计参数图(statistical parametric mapping,SPM)方法对28例患者短时间内两次QCT扫描数据的股骨近段骨密度和骨皮质厚度进行统计分析,获取三维统计参数图。结果所选28例骨折患者短时间内两次QCT扫描数据的股骨近段骨密度和骨皮质厚度的测量结果差异无统计学意义(P0.05),一致性均较好,说明测量结果较为准确。结论股骨近段骨密度和骨皮质厚度的测量方法具有较好的可重复性,为髋部骨折风险评估提供有效手段。

Reproducibility of voxel-based measurement of bone mineral density and cortical thickness of the proximal femur

Objective To provide a technical support for the study of hip fracture, quantitative computed tomography (QCT) was used to analyze the repeatability of voxel-based measurement of proximal femur bone mineral density (BMD) and cortical thickness (CTh). Methods 28 hip fracture patients who had two CT scans in a short time were selected, including 6 males and 22 females. Proximal femur was segmented from QCT image manually. With the idea of voxel-based morphometry (VBM), one proximal femoral structure of the average shape and structure was selected as the standard template, and other proximal femurs were mapped to the standard template by the elastic registration algorithm. CT values were converted to BMD and CTh using the Least Squares and the Levenberg-Marquardt method. Finally, using Statistical Parametric Mapping (SPM) method, we analyzed the BMD and CTh of proximal femur in 28 fracture patients who had two QCT scans in a short time, and obtained three-dimensional statistical parameter map. Results There were no significant differences in the measurement results of proximal femur BMD and CTh of the 28 fracture patients with two QCT scans in a short time (P>0.05), and the results of these two scans had good consistency. This indicates that the measurement results are accurate. Conclusion The voxel-based measurement of proximal femur BMD and CTh has good repeatability and provides an effective method for the risk assessment of hip fracture.