旋转中心偏移对显微CT松质骨定量分析的影响  

The influence of center of rotation on the assessment of trabecular bone densitometric and structural properties

作　　者：盛志峰[1] 徐康[1] 戴如春[1] 伍贤平[1] 廖二元[1] 

机构地区：[1]中南大学湘雅二医院代谢内分泌研究所,湖南长沙410011

出　　处：《中华骨质疏松和骨矿盐疾病杂志》2009年第2期134-141,共8页Chinese Journal Of Osteoporosis And Bone Mineral Research

基　　金：国家自然科学基金资助项目（30400514）;卫生部临床学科重点建设资助项目（2004-468-50）

摘　　要：目的观察旋转中心微小偏移对显微CT测量参数的影响。方法20只7月龄sD大鼠随机分为去卵巢组（OVX）和假手术组（SHAM）。手术后3周处死，应用显微cT扫描胫骨近干骺端。手动校正以获取每次扫描的最佳旋转中心，分析各旋转中心在偏移±0．5、±1．0、±1．5和±2．0像素条件下的密度及微结构参数。结果一般线性模型分析结果显示OVX组与SHAM组比较，表观骨密度、组织骨密度、骨体积分数、骨小梁数量和联接密度明显下降，骨小梁间隔明显增宽（P〈0．05）。组织骨密度、各向异性度、骨小梁面积密度和联接密度随旋转中心的偏移下降，骨体积分数和骨小梁厚度随偏移幅度的加大逐渐升高。旋转中心偏移±1．5像素内，对组织骨密度、骨体积分数、各向异性度和联接密度的测量无影响。而骨小梁厚度和骨小梁面积密度在旋转中心偏移±1．0像素内影响较小。OVX组与SHAM组各参数随旋转中心偏移的变化趋势基本一致。各参数随旋转中心偏移服从二次回归方程趋势。通过二次回归方程拟合，可以获得实际旋转中心。以该中心获取的图像质量高，并能确保定量分析数据的准确。实际旋转中心与人为校正的最佳旋转中心之间存在微小差异。结论旋转中心的微小偏移对表观骨密度、结构模型指数、骨小梁间隔和数量的测量无明显影响。组织骨密度、骨小梁厚度、骨小梁面积密度、骨体积分数、各向异性度和联接密度受旋转中心偏移影响较大。通过二次曲线方程拟合能找到正确的旋转中心，该中心与人为校正获取的最佳旋转中心存在一定误差。Objective To evaluate the influence of center of rotation on the assessment of trabecular bone densitometric and structural properties. Methods Twenty female Sprague-Dawley rats of 7-month-old were randomly assigned to ovariectomized （OVX） and SHAM-operated （SHAM） groups. The left tibiae were harvested at 3 weeks postoperatively. High resolution micro-computed tomography （p, CT） was used to identify the densitometric and microstructural properties of trabeculae in the proximal ends of tibia. After CT scanning, the best artificial rotation center for each scan was obtained. Densitometric and microstructural analysis was performed on the centers at different places away from the best center of ± 0. 5, ± 1.0, ± 1.5 and ± 2. 0 pixels, respectively. Results The general linear model （GLM） repeated measures procedure was used to investigate the difference in the parameters between the two groups （OVX vs. Sham） and the possible effects of center displacements. A significant difference between OVX and SHAM groups was found in all parameters （P 〈 0. 05 ） except Tb. Th, DA and BS/BV. TBMD, DA, BS/BV and ConrL D were decreased while BV/TV and Tb. Th were increased with the center deflection. Variations of these parameters were acceptable when the displacements were limited within ± 1.5 pixels for tBMD, BV/TV, DA and Corm. D, and ± 1.0 pixels for Tb. Th and BS/BV. These changes were similar in both OVX and SHAM groups. The changing curves of bone parameters vs. centers could be well fitted by quadric regression models, by which the actual centers could be acquired. Moreover, there were some differences between the best artificial and actual center. Conclusion The small displacements in the center of rotation would not change the values of total bone mineral content, apparent BMD, SMI, rib. Sp and Th. N. Tissue BMD, BV/TV, BS/BV, Tb. Th, DA and Conn. D would be significantly changed by displacement of the rotation center. The actual center could be obtained by quadric regression models, but ther

关 键 词：显微CT 旋转中心 阈值 骨密度 微结构 

分 类 号：R814.42[医药卫生—影像医学与核医学]