Handels H, Ehrhardt J, Plötz W, Pöppl S J
Institute for Medical Informatics, Medical University of Lübeck, Lübeck, Germany.
Comput Aided Surg. 2001;6(2):65-76. doi: 10.1002/igs.1010.
This article presents the VIRTOPS (VIRTual Operation Planning in Orthopaedic Surgery) software system for virtual preoperative planning and simulation of hip operations. The system is applied to simulate the endoprosthetic reconstruction of the hip joint with hemipelvic replacement, and supports the individual design of anatomically adaptable, modular prostheses in bone tumor surgery. The virtual planning of the operation and the construction of the individual implant are supported by virtual reality techniques. The central step of the operation planning procedure, the placement of the cutting plane in the hip bone, depends strongly on the tumor's position. Segmentation of the tumor and the bones in MR and CT data, as well as fusion of MR and CT image sequences, is necessary to visualize the tumor's position within the hip bone.
Three-dimensional models of the patient's hip are generated based on CT image data. A ROI-based segmentation algorithm enables the separation of the bone tumor in multispectral MR image sequences. A special registration method using segmentation results has been developed to transfer CT and MR data into one common coordinate system. During the 3D planning process, the surgeon simulates the operation and defines the position and geometry of the custom-made endoprosthesis. Stereoscopic visualization and 3D input devices facilitate navigation and 3D interaction in the virtual environment. Special visualization techniques such as texture mapping, color coding of quantitative parameters, and transparency support the determination of the correct position and geometry of the prosthesis.
The VIRTOPS system enables the complete virtual planning of hip operations with endoprosthetic reconstruction, as well as the optimal placement and design of endoprostheses. After the registration and segmentation of CT and MR data, 3D visualizations of the tumor within the bone are generated to support the surgeon during the planning procedure. In the virtual planning environment, individually adapted endoprostheses can be constructed without the need to generate expensive solid 3D models. Furthermore, different operation strategies can be compared easily. Three-dimensional images and digital movies generated during the virtual operation planning can be used for case documentation and patient information purposes.
本文介绍了用于髋关节手术虚拟术前规划和模拟的VIRTOPS（骨科手术虚拟操作规划）软件系统。该系统用于模拟髋关节半骨盆置换的假体植入重建，并支持骨肿瘤手术中解剖适应性模块化假体的个性化设计。手术的虚拟规划和个性化植入物的构建由虚拟现实技术提供支持。手术规划程序的核心步骤，即髋关节骨切割平面的放置，很大程度上取决于肿瘤的位置。对MR和CT数据中的肿瘤和骨骼进行分割，以及融合MR和CT图像序列，对于可视化肿瘤在髋关节骨内的位置是必要的。
基于CT图像数据生成患者髋关节的三维模型。基于感兴趣区域的分割算法能够在多光谱MR图像序列中分离骨肿瘤。已开发出一种使用分割结果的特殊配准方法，以将CT和MR数据转换到一个公共坐标系中。在三维规划过程中，外科医生模拟手术并定义定制假体的位置和几何形状。立体可视化和三维输入设备便于在虚拟环境中导航和进行三维交互。特殊的可视化技术，如纹理映射、定量参数的颜色编码和透明度，有助于确定假体的正确位置和几何形状。
VIRTOPS系统能够实现髋关节假体植入重建手术的完整虚拟规划，以及假体的最佳放置和设计。在对CT和MR数据进行配准和分割后，生成骨内肿瘤的三维可视化图像，以在规划过程中为外科医生提供支持。在虚拟规划环境中，可以构建个性化适配的假体，而无需生成昂贵的实体三维模型。此外，可以轻松比较不同的手术策略。虚拟手术规划过程中生成的三维图像和数字电影可用于病例记录和患者信息目的。
