Technical Note: Cortical thickness and density estimation from clinical CT using a prior thickness-density relationship
Technical Note: Cortical thickness and density estimation from clinical CT using a prior thickness-density relationship
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DOI：
10.1118/1.4944501
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发表时间：
2016-04-01
期刊：
影响因子：
3.8
通讯作者：
van Rietbergen, Bert
中科院分区：
文献类型：
--
作者：
Humbert, Ludovic;Marangalou, Javad Hazrati;van Rietbergen, Bert
目的：皮质厚度和密度是决定骨结构强度的关键因素。计算机断层扫描（CT）是一种可能的方式来分析在三维皮层。本文提出了一种基于模型的临床CT图像皮质骨厚度和密度测量方法。方法：将皮质密度变化建模为皮质厚度和密度、皮质位置、周围组织密度和成像模糊的函数。分析了尸体股骨近端高分辨率微ct数据，以确定皮质厚度与密度之间的关系。这种厚度-密度关系被用作纳入模型的先验信息，以便从临床CT体积中获得皮质厚度和密度的准确测量。该方法通过23具尸体近端股骨的微ct扫描得到验证。利用微CT数据生成不同体素大小的临床CT模拟图像。利用该方法从模拟图像中估计皮质厚度和密度，并与微ct图像测量结果进行比较，以评估体素大小对方法准确性的影响。然后，对23例标本中的19例进行临床CT扫描。利用该方法从临床CT图像中估计皮质厚度和密度，并与显微CT测量值进行比较。最后，我们进行了一项病例对照研究，包括20名骨质疏松症患者和20名骨密度正常的年龄匹配的对照组，以在临床环境中评估所提出的方法。结果：使用最小体素（0.33x0.33x0.5 mm(3)）的模拟临床CT体积，皮质厚度（密度）估计误差为0.07 +/- 0.19 mm(-18 +/- 92 mg/cm(3))；使用最大体素（1.0 × 1.0 × 3.0 mm(3)）的模拟临床CT体积，皮质厚度（密度）估计误差为0.10 +/- 0.24 mm（-10 +/- 115 mg/cm(3)）。观察到皮质厚度和密度估计误差随体素大小而增加的趋势，并且对于薄皮质更为明显。利用23个样本中19个的临床CT数据，发现皮质厚度的平均误差为0.18 +/- 0.24 mm，密度的平均误差为15 +/- 106 mg/cm(3)。病例对照研究显示，骨质疏松患者股骨近端皮质较薄，皮质密度较低，与年龄匹配的对照组相比，平均差异为-0.8 mm和-58.6 mg/cm(3) （p值< 0.001）。结论：该方法可能是一种很有前途的方法，用于定量皮质骨厚度和密度的临床常规影像学技术。未来的工作将集中在研究这种方法如何改善骨结构机械强度的估计，预防骨折和骨质疏松症的管理。(C) 2016年美国医学物理学家协会。
Purpose: Cortical thickness and density are critical components in determining the strength of bony structures. Computed tomography (CT) is one possible modality for analyzing the cortex in 3D. In this paper, a model-based approach for measuring the cortical bone thickness and density from clinical CT images is proposed.Methods: Density variations across the cortex were modeled as a function of the cortical thickness and density, location of the cortex, density of surrounding tissues, and imaging blur. High resolution micro-CT data of cadaver proximal femurs were analyzed to determine a relationship between cortical thickness and density. This thickness-density relationship was used as prior information to be incorporated in the model to obtain accurate measurements of cortical thickness and density from clinical CT volumes. The method was validated using micro-CT scans of 23 cadaver proximal femurs. Simulated clinical CT images with different voxel sizes were generated from the micro-CT data. Cortical thickness and density were estimated from the simulated images using the proposed method and compared with measurements obtained using the micro-CT images to evaluate the effect of voxel size on the accuracy of the method. Then, 19 of the 23 specimens were imaged using a clinical CT scanner. Cortical thickness and density were estimated from the clinical CT images using the proposed method and compared with the micro-CT measurements. Finally, a case-control study including 20 patients with osteoporosis and 20 age-matched controls with normal bone density was performed to evaluate the proposed method in a clinical context.Results: Cortical thickness (density) estimation errors were 0.07 +/- 0.19 mm (-18 +/- 92 mg/cm(3)) using the simulated clinical CT volumes with the smallest voxel size (0.33x0.33x0.5 mm(3)), and 0.10 +/- 0.24 mm (-10 +/- 115 mg/cm(3)) using the volumes with the largest voxel size (1.0x1.0x3.0 mm(3)). A trend for the cortical thickness and density estimation errors to increase with voxel size was observed and was more pronounced for thin cortices. Using clinical CT data for 19 of the 23 samples, mean errors of 0.18 +/- 0.24 mm for the cortical thickness and 15 +/- 106 mg/cm(3) for the density were found. The case-control study showed that osteoporotic patients had a thinner cortex and a lower cortical density, with average differences of -0.8 mm and -58.6 mg/cm(3) at the proximal femur in comparison with age-matched controls (p-value < 0.001).Conclusions: This method might be a promising approach for the quantification of cortical bone thickness and density using clinical routine imaging techniques. Future work will concentrate on investigating how this approach can improve the estimation of mechanical strength of bony structures, the prevention of fracture, and the management of osteoporosis. (C) 2016 American Association of Physicists in Medicine.