三维超声图像引导机器人系统在精确微波凝固治疗肝脏恶性肿瘤中的应用。
Three-dimensional ultrasound image-guided robotic system for accurate microwave coagulation of malignant liver tumours.
机构信息
Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI 48823, USA.
出版信息
Int J Med Robot. 2010 Sep;6(3):256-68. doi: 10.1002/rcs.313.
BACKGROUND
The further application of conventional ultrasound (US) image-guided microwave (MW) ablation of liver cancer is often limited by two-dimensional (2D) imaging, inaccurate needle placement and the resulting skill requirement. The three-dimensional (3D) image-guided robotic-assisted system provides an appealing alternative option, enabling the physician to perform consistent, accurate therapy with improved treatment effectiveness.
METHODS
Our robotic system is constructed by integrating an imaging module, a needle-driven robot, a MW thermal field simulation module, and surgical navigation software in a practical and user-friendly manner. The robot executes precise needle placement based on the 3D model reconstructed from freehand-tracked 2D B-scans. A qualitative slice guidance method for fine registration is introduced to reduce the placement error caused by target motion. By incorporating the 3D MW specific absorption rate (SAR) model into the heat transfer equation, the MW thermal field simulation module determines the MW power level and the coagulation time for improved ablation therapy. Two types of wrists are developed for the robot: a 'remote centre of motion' (RCM) wrist and a non-RCM wrist, which is preferred in real applications.
RESULTS
The needle placement accuracies were < 3 mm for both wrists in the mechanical phantom experiment. The target accuracy for the robot with the RCM wrist was improved to 1.6 +/- 1.0 mm when real-time 2D US feedback was used in the artificial-tissue phantom experiment. By using the slice guidance method, the robot with the non-RCM wrist achieved accuracy of 1.8 +/- 0.9 mm in the ex vivo experiment; even target motion was introduced. In the thermal field experiment, a 5.6% relative mean error was observed between the experimental coagulated neurosis volume and the simulation result.
CONCLUSION
The proposed robotic system holds promise to enhance the clinical performance of percutaneous MW ablation of malignant liver tumours.
背景
传统超声（US）引导微波（MW）消融肝癌的进一步应用常受到二维（2D）成像、针道不准确和由此导致的技能要求的限制。三维（3D）图像引导机器人辅助系统提供了一种有吸引力的替代方案，使医生能够进行一致、准确的治疗，提高治疗效果。
方法
我们的机器人系统通过以实用和用户友好的方式集成成像模块、针驱动机器人、MW 热场模拟模块和手术导航软件来构建。机器人根据从自由追踪 2D B 扫描重建的 3D 模型执行精确的针道放置。引入了定性切片引导方法来进行精细注册，以减少由于目标运动引起的放置误差。通过将 3D MW 比吸收率（SAR）模型纳入传热方程，MW 热场模拟模块确定 MW 功率水平和凝固时间，以改善消融治疗。机器人开发了两种腕部：一种是“远程运动中心”（RCM）腕部，另一种是在实际应用中更受欢迎的非 RCM 腕部。
结果
在机械体模实验中，两种腕部的针道放置精度均<3mm。在人工组织体模实验中使用实时 2D US 反馈时，具有 RCM 腕部的机器人的目标精度提高到 1.6 +/- 1.0mm。通过使用切片引导方法，在离体实验中具有非 RCM 腕部的机器人达到了 1.8 +/- 0.9mm 的精度；即使引入了目标运动。在热场实验中，实验凝固神经节体积与模拟结果之间观察到 5.6%的相对平均误差。
结论
所提出的机器人系统有望提高经皮 MW 消融恶性肝肿瘤的临床性能。
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