Method for cortical bone structural analysis from magnetic resonance images
Method for cortical bone structural analysis from magnetic resonance images
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DOI：
10.1016/j.acra.2005.06.012
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发表时间：
2005-10-01
影响因子：
4.8
通讯作者：
Wehrli, FW
中科院分区：
文献类型：
--
作者：
Gomberg, BR;Saha, PK;Wehrli, FW
理由和目标。作为评估骨强度的手段，皮质骨结构的定量评价通常基于通过双能X射线吸收测定法（DXA）或计算机断层扫描获得的图像来完成。磁共振（MR）成像对于该任务具有潜在的优势，因为其允许以高空间分辨率在任意扫描平面中成像。然而，要使这种方法实用化，必须克服几个障碍，包括解决与非线性接收线圈灵敏度、骨髓成分变化以及骨膜等强度组织的存在相关的问题，这些问题都使分割复杂化。本研究的目的是开发MR采集和分析方法，用于检测股骨颈等复杂几何结构中的皮质边界。皮质边界检测是通过径向追踪与骨的骨膜和骨内膜边界相交的强度分布来实现的。随后将轮廓标准化为骨髓信号的强度，用形态学图像算子处理，并二值化。将得到的边界映射回空间图像，并删除错误的边界点。根据检测到的皮质边界，计算皮质横截面积和厚度。在1.5特斯拉场强下获得的高分辨率图像的基础上，对皮质骨标本和人类志愿者的方法进行了评价。为了评估该方法是否敏感，以检测预期的依赖性的皮质参数在承重骨的整体体质，10名妇女年龄在46-73岁（平均年龄，56岁）进行了皮质成像协议在股骨近端，并将结果与DXA骨密度参数的髋关节和脊柱。繁殖率约为2%。研究的10名女性股骨颈的双斜位图像显示，皮质横截面积与身高密切相关（r = 0.88; p = 0.0008），而皮质直径与年龄接近显著性（r = 0.61; p = 0.06）。在标本中的一些皮质参数的测量表明分辨率依赖。然而，请注意，在研究的所有分辨率中，每个参数内的标本排名保持不变。数据表明，新方法在任意解剖位置的标准临床MR扫描仪上具有稳健性和适用性，可产生具有临床意义的定量结果。
Rationale and Objectives. Quantitative evaluation of cortical bone architecture as a means to assess bone strength typically is accomplished on the basis of images obtained by means of dual-energy X-ray absorptiometry (DXA) or computed tomography. Magnetic resonance (MR) imaging has potential advantages for this task in that it allows imaging in arbitrary scan planes at high spatial resolution. However, several hurdles have to be overcome to make this approach practical, including resolution of issues related to nonlinear receive coil sensitivity, variations in marrow composition, and the presence of periosteal isointense tissues, which all complicate segmentation. The aim of this study is to develop MR acquisition and analysis methods optimized for the detection of cortical boundaries in such complex geometries as the femoral neck.Materials and Methods. Cortical boundary detection is achieved by radially tracing intensity profiles that intersect the periosteal and endosteal boundaries of bone. Profiles subsequently are normalized to the intensity of the marrow signal, processed with morphologic image operators, and binarized. The resulting boundaries are mapped back onto the spatial image, and erroneous boundary points are removed. From the detected cortical boundaries, cortical cross-sectional area and thickness are computed. The method was evaluated on cortical bone specimens and human volunteers on the basis of high-resolution images acquired at a 1.5-Tesla field strength. To assess whether the method is sensitive to detect the expected dependencies of cortical parameters in weight-bearing bone on overall habitus, 10 women aged 46-73 years (mean age, 56 years) underwent the cortical imaging protocol in the proximal femur, and results were compared with DXA bone mineral density parameters of the hip and spine.Results. Reproducibility was approximately 2%. Double oblique images of the femoral neck in the 10 women studied showed that cortical cross-sectional area correlated strongly with height (r = 0.88; p =.0008), whereas cortical diameter versus age approached significance (r = 0.61; p =.06). Measurements in specimens of some cortical parameters indicated resolution dependence. However, note that specimen ranking within each parameter remained constant across all resolutions studied.Conclusion. Data suggest the new method to be robust and applicable on standard clinical MR scanners at arbitrary anatomic locations to yield clinically meaningful quantitative results.