Bowers M E, Trinh N, Tung G A, Crisco J J, Kimia B B, Fleming B C
Bioengineering Laboratory, Division of Orthopaedic Research, The Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, RI 02903, United States.
Osteoarthritis Cartilage. 2008 Oct;16(10):1167-73. doi: 10.1016/j.joca.2008.03.005. Epub 2008 Apr 14.
To assess the reliability and accuracy of manual and semi-automated segmentation methods for quantifying knee cartilage thickness. This study employed both manual and LiveWire-based semi-automated segmentation methods, ex vivo and in vivo, to measure tibiofemoral (TF) cartilage thickness.
The articular cartilage of a cadaver knee and a healthy volunteer's knee were segmented manually and with LiveWire from multiple 3T MR images. The cadaver specimen's cartilage thickness was also evaluated with a 3D laser scanner, which was assumed to be the gold standard. Thickness measurements were made within specific cartilage regions. The reliability of each segmentation method was assessed both ex vivo and in vivo, and accuracy was assessed ex vivo by comparing segmentation results to those obtained with laser scanning.
The cadaver specimen thickness measurements showed mean coefficients of variation (CVs) of 4.16%, 3.02%, and 1.59%, when evaluated with manual segmentation, LiveWire segmentation, and laser scanning, respectively. The cadaver specimen showed mean absolute errors versus laser scanning of 4.07% and 7.46% for manual and LiveWire segmentation, respectively. In vivo thickness measurements showed mean CVs of 2.71% and 3.65% when segmented manually and with LiveWire, respectively.
Manual segmentation, LiveWire segmentation, and laser scanning are repeatable methods for quantifying knee cartilage thickness; however, the measurements are technique-dependent. Ex vivo, the manual segmentation error was distributed around the laser scanning mean, while LiveWire consistently underestimated laser scanning by 8.9%. Although LiveWire offers repeatability and decreased segmentation time, manual segmentation more closely approximates true cartilage thickness, particularly in cartilage contact regions.
评估用于量化膝关节软骨厚度的手动和半自动分割方法的可靠性和准确性。本研究采用手动和基于LiveWire的半自动分割方法，在体外和体内测量胫股（TF）软骨厚度。
从多个3T MR图像中手动和使用LiveWire对尸体膝关节和健康志愿者膝关节的关节软骨进行分割。还使用3D激光扫描仪评估尸体标本的软骨厚度，将其视为金标准。在特定软骨区域内进行厚度测量。在体外和体内评估每种分割方法的可靠性，并通过将分割结果与激光扫描获得的结果进行比较在体外评估准确性。
尸体标本厚度测量结果显示，分别采用手动分割、LiveWire分割和激光扫描评估时，平均变异系数（CV）分别为4.16%、3.02%和1.59%。与激光扫描相比，尸体标本手动分割和LiveWire分割的平均绝对误差分别为4.07%和7.46%。体内厚度测量结果显示，手动分割和使用LiveWire分割时，平均CV分别为2.71%和3.65%。
手动分割、LiveWire分割和激光扫描是量化膝关节软骨厚度的可重复方法；然而，测量结果取决于技术。在体外，手动分割误差分布在激光扫描平均值周围，而LiveWire始终比激光扫描低估8.9%。尽管LiveWire具有可重复性且分割时间缩短，但手动分割更接近真实软骨厚度，尤其是在软骨接触区域。
