Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, USA.
J Digit Imaging. 2009 Oct;22(5):483-91. doi: 10.1007/s10278-008-9151-y. Epub 2008 Sep 3.
Medical imaging technologies have allowed for in vivo exploration and evaluation of the human musculoskeletal system. Three-dimensional bone models generated using image-segmentation techniques provide a means to optimize individualized orthopedic surgical procedures using engineering analyses. However, many of the current segmentation techniques are not clinically practical due to the required time and human intervention. As a proof of concept, we demonstrate the use of an expectation maximization (EM) algorithm to segment the hand phalanx bones, and hypothesize that this semi-automated technique will improve the efficiency while providing similar definitions as compared to a manual rater. Our results show a relative overlap of the proximal, middle, and distal phalanx bones of 0.83, 0.79, and 0.72 for the EM technique when compared to validated manual segmentations. The EM segmentations were also compared to 3D surface scans of the cadaveric specimens, which resulted in distance maps showing an average distance for the proximal, middle, and distal phalanx bones of 0.45, 0.46, and 0.51 mm, respectively. The EM segmentation improved on the segmentation speed of the manual techniques by a factor of eight. Overall, the manual segmentations had greater relative overlap metric values, which suggests that the manual segmentations are a better fit to the actual surface of the bone. As shown by the comparison to the bone surface scans, the EM technique provides a similar representation of the anatomic structure and offers an increase in efficiency that could help to reduce the time needed for defining anatomical structures from CT scans.
医学成像技术允许对人体肌肉骨骼系统进行体内探索和评估。使用图像分割技术生成的三维骨骼模型为使用工程分析优化个体化骨科手术程序提供了一种手段。然而，由于所需的时间和人为干预，许多当前的分割技术在临床上并不实用。作为概念验证，我们展示了使用期望最大化 (EM) 算法对手指指骨进行分割，并假设这种半自动技术将提高效率，同时与手动评分器相比提供相似的定义。我们的结果显示，与经过验证的手动分割相比，EM 技术对手指近节、中节和远节指骨的相对重叠分别为 0.83、0.79 和 0.72。EM 分割还与尸体标本的 3D 表面扫描进行了比较，得到的距离图显示，近节、中节和远节指骨的平均距离分别为 0.45、0.46 和 0.51 毫米。EM 分割将手动技术的分割速度提高了 8 倍。总体而言，手动分割具有更高的相对重叠度量值，这表明手动分割更适合骨骼的实际表面。如与骨表面扫描的比较所示，EM 技术提供了对解剖结构的相似表示，并提高了效率，可以帮助减少从 CT 扫描定义解剖结构所需的时间。
