Hopper T A J, Meder R, Pope J M
School of Physical and Chemical Sciences, Queensland University of Technology, Brisbane, Australia.
Magn Reson Imaging. 2004 Sep;22(7):953-61. doi: 10.1016/j.mri.2004.02.008.
Magnetic resonance imaging (MRI) has been used to analyze trabecular bone architecture in femur heads taken from adult Wistar rats. The aim of this study was to validate the use of MRI in assessing trabecular structure and morphology by comparing standard measures of bone morphology in the rat femur obtained from high resolution MRI with those obtained by conventional optical microscopy and by scanning electron microscopy (SEM). MR images were obtained on a Bruker 4.7 T micro-imaging system using a three-dimensional spin echo sequence with spatial resolution of 23 microm in-plane and a slice thickness of 39 microm. Optical images were obtained by de-calcifying the bone in EDTA and then sectioning 5-microm-thick slices. SEM images were obtained from bone embedded in epoxy resin with surface preparation by diamond polishing. Values of standard bone morphological parameters were compared and correlation coefficients between the MRI and the optical- and SEM-derived measures of morphology were calculated. Partial volume effects in MRI were minimized in this study by the use of very thin slices, yielding better agreement with optical- and SEM-derived measures of trabecular bone morphology than have been obtained in previous studies. Correlations between the MRI and optical data were significantly lower than those between the MRI and SEM data. Effects of de-calcification were also investigated. The results indicate that comparison of MRI with thin (de-calcified) optical images may be inherently flawed due to the destructive de-calcification and sectioning process used to prepare samples for the optical imaging.
磁共振成像（MRI）已被用于分析成年Wistar大鼠股骨头的小梁骨结构。本研究的目的是通过比较从高分辨率MRI获得的大鼠股骨骨形态学标准测量值与通过传统光学显微镜和扫描电子显微镜（SEM）获得的测量值，来验证MRI在评估小梁结构和形态方面的应用。使用三维自旋回波序列在Bruker 4.7 T微成像系统上获得MR图像，其平面内空间分辨率为23微米，切片厚度为39微米。通过在乙二胺四乙酸（EDTA）中对骨进行脱钙，然后切成5微米厚的切片来获得光学图像。从嵌入环氧树脂的骨中获得SEM图像，并通过金刚石抛光进行表面处理。比较标准骨形态学参数的值，并计算MRI与光学和SEM衍生的形态学测量值之间的相关系数。在本研究中，通过使用非常薄的切片将MRI中的部分容积效应降至最低，与先前研究相比，与光学和SEM衍生的小梁骨形态学测量值的一致性更好。MRI与光学数据之间的相关性明显低于MRI与SEM数据之间的相关性。还研究了脱钙的影响。结果表明，由于用于光学成像样品制备的破坏性脱钙和切片过程，将MRI与薄（脱钙）光学图像进行比较可能存在固有缺陷。
