Computer-Assisted Applications in Medicine (CAiM), ETH Zurich, Zurich, Switzerland.
Computer Assisted Research and Development (CARD), Balgrist University Hospital, University of Zurich, Zurich, Switzerland.
Int J Comput Assist Radiol Surg. 2018 Jun;13(6):827-836. doi: 10.1007/s11548-018-1756-0. Epub 2018 Apr 5.
For guidance of orthopedic surgery, the registration of preoperative images and corresponding surgical plans with the surgical setting can be of great value. Ultrasound (US) is an ideal modality for surgical guidance, as it is non-ionizing, real time, easy to use, and requires minimal (magnetic/radiation) safety limitations. By extracting bone surfaces from 3D freehand US and registering these to preoperative bone models, complementary information from these modalities can be fused and presented in the surgical realm.
A partial bone surface is extracted from US using phase symmetry and a factor graph-based approach. This is registered to the detailed 3D bone model, conventionally generated for preoperative planning, based on a proposed multi-initialization and surface-based scheme robust to partial surfaces.
36 forearm US volumes acquired using a tracked US probe were independently registered to a 3D model of the radius, manually extracted from MRI. Given intraoperative time restrictions, a computationally efficient algorithm was determined based on a comparison of different approaches. For all 36 registrations, a mean (± SD) point-to-point surface distance of [Formula: see text] was obtained from manual gold standard US bone annotations (not used during the registration) to the 3D bone model.
A registration framework based on the bone surface extraction from 3D freehand US and a subsequent fast, automatic surface alignment robust to single-sided view and large false-positive rates from US was shown to achieve registration accuracy feasible for practical orthopedic scenarios and a qualitative outcome indicating good visual image alignment.
为了指导骨科手术，将术前图像和相应的手术计划与手术环境进行配准具有重要价值。超声（US）是一种理想的手术引导方式，因为它是非电离的、实时的、易于使用的，并且对最小（磁/辐射）安全限制要求较低。通过从 3D 自由手 US 中提取骨表面，并将这些表面注册到术前骨模型中，可以融合这些模态的补充信息并在手术领域呈现。
使用相位对称和基于因子图的方法从 US 中提取部分骨表面。根据提出的多初始化和基于表面的方案，基于该方案，该表面对部分表面具有鲁棒性，将其注册到常规生成的术前规划的详细 3D 骨模型上。
使用跟踪 US 探头采集了 36 个前臂 US 体积，这些体积分别独立地注册到从 MRI 手动提取的桡骨 3D 模型上。由于术中时间限制，根据不同方法的比较，确定了一种计算效率高的算法。对于所有 36 次配准，从手动金标准 US 骨注释（未在配准过程中使用）到 3D 骨模型的平均（±SD）点到点表面距离为[公式：见正文]。
从 3D 自由手 US 中提取骨骼表面并随后进行快速、自动的表面对齐的注册框架，该框架对单边视图和来自 US 的高错误率具有鲁棒性，该框架被证明能够实现适用于实际骨科场景的注册精度，并具有良好的视觉图像对齐的定性结果。
