Precisely Shaped Acoustic Ablation of Tumors Under 3D Ultrasound Image Guidance

摘要 许多最近的研究已经证明了间质消融方法治疗 肝肿瘤，包括化学消融、冷冻消融和使用RF等能量源的热消融， 激光、微波或聚焦超声。尽管有这些有希望的结果，目前的系统仍然高度 依赖于操作者的技术，并且不能治疗许多肿瘤，因为几乎不能控制肿瘤的大小和形状 坏死区的位置，并且无法控制消融器在组织内的轨迹。解决这个问题需要 末端效应器设计的进步、消融器装置到期望目标位置的精确操纵，以及真实的- 对坏死区进行时间监测，以确保完成治疗。术中超声成像 提供了也许是最佳和最容易获得的方法为目标，但同时手动 B型超声（US）探头和消融装置的操作是一项具有挑战性的任务， 即使是最有经验的医生也会犯下重大错误。组织变形和目标运动 使得极难将烧蚀装置精确地放置到目标中。不规则形状目标 体积通常需要多次插入和几个重叠的热损伤， 在不对周围环境造成过度损害的情况下， 正常组织为了解决这些问题，我们提出了一种创新的方法， 关于空间配准的非手术US体积的跟踪和工具配准，而不依赖于 外部追踪装置这种三维超声（3DUS）将与灵活的蛇形 一种称为主动套管（AC）的轻便廉价机器人，用于帮助精确放置 可操纵的超声热消融器进入肝脏，并实时监测组织消融的进展 3D注册超声。植入式或组织间高能超声治疗器的研究进展 已经证明了非常可控和穿透的加热模式， 动态地改变，为顺应性热外科手术提供理想的机制。这种可控性和 穿透是非常期望的，并且将提供对现有RF和微波的显著改进。 (MW)用于肝肿瘤微创热消融的技术。然而，迄今为止， 这种微创技术的评价主要限于体内犬前列腺， 中度灌注组织，未包括必要的设计迭代和全面评价 用于治疗高灌注肝组织内的肿瘤。热疗的初步热数据 灌注肝脏（C部分）令人鼓舞。超声间质热疗（USITT）技术是 我们将扩展该技术，以优化其在肝肿瘤治疗中的应用。的 这项研究和开发的总体目标是提供一种用于转向，放置， 引导、适形消融治疗的经皮递送和治疗的在线监测。

ABSTRACT Many recent studies have demonstrated the efficacy of interstitial ablative approaches for the treatment of hepatic tumors, including chemical ablation, cryoablation, and thermal ablation using energy sources like RF, laser, microwave, or focused ultrasound. Despite these promising results, current systems remain highly dependent on operator skill, and cannot treat many tumors because there is little control of the size and shape of the zone of necrosis, and no control over ablator trajectory within tissue. Remedying this problem requires advances in end-effector design, precise steering of the ablator device to the desired target location, and real- time monitoring of the zone of necrosis to ensure complete treatment. Intra-procedure ultrasound imaging provides perhaps the optimal and most readily available method for targeting, but simultaneous manual handling of the B-mode ultrasound (US) probe and the ablator device is a challenging task that is prone to significant errors in the hands of even the most experienced physicians. Tissue deformation and target motion make it extremely difficult to place the ablator device precisely into the target. Irregularly shaped target volumes typically require multiple insertions and several overlapping thermal lesions, which are even more challenging to accomplish in a precise and timely manner without causing excessive damage to surrounding normal tissues. In answer to these problems, we propose to develop an innovative method for accurate tracking and tool registration with respect to spatially-registered intaoperative US volumes without relying on an external tracking device. This three-dimensional ultrasound (3DUS) will be integrated with a flexible, snake-like lightweight and inexpensive robotic, called the Active Cannula (AC), to facilitate precise placement of a steerable ultrasound thermal ablator into the liver and to monitor the progress of tissue ablation with real-time 3D registered ultrasound. Recent developments of implantable or interstitial high-power ultrasound applicators have demonstrated extremely controllable and penetrating heating patterns which can be shaped and dynamically altered, providing an ideal mechanism for conformable thermal surgery. This controllability and penetration is highly desirable and would provide significant improvement over existing RF and microwave (MW) technology used for minimally invasive thermal ablation of liver tumors. However, to date the extensive evaluation of this minimally invasive technology has been limited mostly to in vivo canine prostates and moderately perfused tissues, and have not included the design iterations and thorough evaluations necessary for treating tumors within highly perfused liver tissue. The preliminary thermal data from thermal therapy of perfused liver (Section C) are encouraging. Ultrasound Interstitial Thermal Therapy (USITT) technology is promising and we will extend the technology to optimize its use for the treatment of hepatic tumors. The overall goal of this research and development is to provide a true closed-loop system for steering, placement, guidance, percutaneous delivery of conformal ablative therapy, and on-line monitoring of treatment.