X射线显微CT用于大鼠骨小梁结构分析的研究

应用X射线显微CT(X-μCT)对正常及骨质疏松大鼠的骨小梁结构进行了分析，并与骨组织形态计量法的测量值进行了比较，探讨了X射线光谱技术在骨结构分析中的应用。实验对大鼠骨样品进行X-μCT扫描，扫描条件为 80 kVp，80 μA，360°旋转，帧平均4帧，角度增益 0.4°，分辨率14 μm。三维重建并分析了骨小梁结构，结构参数包括骨体积分数(BV/TV)、骨小梁厚度(Tb.Th)、骨小梁数量(Tb.N)以及骨小梁间隔(Tb.Sp)。结果表明，采用X-μCT分析不同组大鼠的骨小梁结构参数值之间存在显著差异(P<0.05)，测定值与传统骨组织形态计量法的测定值显著相关，其中胫骨骨小梁BV/TV，Tb.Th，Tb.N，Tb.Sp的相关系数r分别为0.984，0.960，0.995，0.988，腰椎骨小梁各结构参数的相关系数分别为0.938，0.968，0.877，0.951。因此，X-μCT可以较好地呈现并区分正常骨组织、骨质疏松骨组织以及经雌激素治疗后骨组织的微观结构，可以实现对骨小梁结构参数的分析测定，与骨组织形态计量法相比是一种更精确、立体、快速且无损测量骨微结构和评价骨质量的方法。

A Quantitative Trabecular Structural Analysis Using X-Ray Micro CT in Ovariectomized Rats

The objective of the present paper was to evaluate the X-ray three-dimensional micro-computed tomography (X-μCT) method applied in assessing the trabecular structure in ovariectomized rats. Three-month-old female Sprague-Dawley rats (n=30) were ovariectomized (OVX) or sham-operated (SHAM). OVX rats were treated with vehicle, or 17β-estradiol (E2, positive control) for 3 months. For the conventional histomorphometric analysis, undecalcified sections were prepared and stained with the Li Chunhong technique to obtain high-contrast two-dimensional images. Prior to the histologic sectioning the samples were measured by X-μCT, providing a 14 μm resolution. The morphometric parameters computed by both methods in two or three dimensions, respectively, were bone volume over total volume (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N) and trabecular separation (Tb.Sp). Results showed that there were significant differences in the trabecular structure among three groups. In the OVX control group, the platelike structure was mostly resolved into a rodlike structure, with lots of the connecting rods missing. Whereas in OVX+E2 groups, this loss of trabecular bone mass and connectivity was prevented, with the results being nearly the same as those in the SHAM group. It was shown that highly significant correlations between conventional histology and X-μCT for BV/TV，Tb.Th，Tb.N and Tb.Sp were 0.984, 0.960, 0.995, and 0.988 in tibia，and 0.938，0.968，0.877 and 0.951 in lumbar. The high correlations between conventional histomorphometric and micro-tomographic analysis are very promising for the use of micro-tomographic imaging. X-μCT is a nondestructive, fast, and very precise procedure that allows the measurement of cancellous tissue in unprocessed biopsies or small bones, as well as a fully automatic determination of three-dimensional morphometric indices.