Adjusting for the partial volume effect in cortical bone analyses of pQCT images.
Adjusting for the partial volume effect in cortical bone analyses of pQCT images.
复制标题
调整 pQCT 图像皮质骨分析中的部分体积效应。
DOI：
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发表时间：
2004
影响因子：
1.9
通讯作者：
D. Felsenberg
中科院分区：
文献类型：
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作者：
Jörn Rittweger;I. Michaelis;M. Giehl;P. Wüsecke;D. Felsenberg
由于影响具有不同大小或以不同分辨率评估的对象(例如，骨骼)的部分体积效应，对计算机断层扫描图像的定量分析容易产生误差。我们建立了一组方程，既适用于模拟皮质骨的部分体积效应，也适用于进行相应的调整。用含1%硅的铝制作了7个中空圆柱体和2个长方体体模。用pQCT机(XCT2002，Stratec MedizinTechnik，Pforzheim，德国)扫描标本，并用集成软件5.50版进行分析。在空气和林格溶液中以不同的分辨率(体素大小=0.20到0.75 mm)进行测量，并在不同的检测阈值下进行分析。应用校正方程组，可以将皮质密度的误差减小80%左右。在与皮质骨密度和背景密度的平均值相等的阈值(Theta0)下，皮质区的评估误差可以忽略不计。当选择0作为检测阈值时，密度误差降低到2%以下。我们建议分几个步骤评估皮质面积和皮质密度，然后首先评估面积和密度。每当需要“真实世界”值或比较不同大小的对象时，应用此方法应该是有益的。
Quantitative analyses of computed tomography images are prone to errors due to the partial volume effect which affects objects (e.g., bones) that have a different size or are assessed with different resolution. We have developed a set of equations suitable for both modeling the partial volume effect in cortical bone and for performing the corresponding adjustment. Seven hollow cylinders and 2 cuboid phantoms were made out of Al with 1% Si. The specimens were scanned with a pQCT machine (XCT2002, Stratec Medizintechnik, Pforzheim, Germany) and analyzed with the integrated software, version 5.50. Measurements were performed at different resolutions (voxel size=0.20 to 0.75 mm), both in air and in Ringer solution, and analyses were performed at different detection thresholds. Applying the correcting equations set we could reduce the errors in cortical density by about 80%. The cortical area was assessed with a negligible error at a threshold (theta0) that is equivalent to the mean of the cortical bone density and of the background density. On choosing theta0 as the detection threshold the error in density was lowered to less than 2%. We propose to assess cortical area and cortical density in several steps, first assessing the area and density thereafter. Applying this method should be beneficial whenever "true world" values are required, or objects of different size are compared.