Safe Flexible Intracerebral Navigation with Steerable Needles

描述（由申请人提供）：针头放置的准确性在诸如肿瘤手术和深部脑刺激（DBS）等脑干预中至关重要，并且需要改进以提高治疗效果。为了满足这一需求，我们开发了一种计算机控制系统，设计用于引导柔性针头穿过脑组织，使用一种优雅的简单技术，在插入过程中以“职责循环”的方式缓慢旋转针头，并按比例控制转向角度。该系统可用于到达大脑深处的目标，并可在需要时绕道而行，以避免损伤敏感区域。该系统的初步测试已在体外明胶基质和人体尸体中进行。迄今为止，对该技术进行的测试仅侧重于达到特定目标的有效性。仍有几个未解决的需求，特别是在体内跟踪柔性探针尖端的方法的发展。然而，在解决这些问题之前，需要在几个领域进行研究，以确保该技术的安全性。本建议的具体目的如下：调整尖端几何形状和速度包络以保证脑实质的安全。这将需要对针尖几何形状和针尖旋转过程进行有限元建模，以优化探针的材料、斜角、边缘锐度、旋转速度和插入速度，以避免损伤组织。这项工作的结果将在体外和体内的新鲜动物脑组织中进行验证。2. 调整尖端几何形状和速度包络，以确保与血管的安全接触。这一目标将包括在猪模型中进行体内测试，与标准的直侧活检针进行比较，以验证针头的几何形状、旋转速度和探针的插入速度，以避免在插入过程中损伤接触的血管。目标是将通过CT检测到的出血量限制在目前临床直探头脑针设计所显示的出血量。3. 优化设计和速度包络线，以避免沿曲针轨迹长度的组织损伤。与直探头不同，柔性针的插入当然会沿着针径的外曲率施加一定的应力。因此，除了上述专门处理针尖的工作外，还需要模拟柔性针与沿轴的组织之间的相互作用，优化针规和速度包络线的设计，以避免沿轨迹损伤组织。这项工作也将有助于防止任何可能性的“旋转”或“鞭打”运动的尖端的柔性针轴旋转。这项工作将在体外动物组织中进行验证，然后在猪体内模型中进行验证。这些目标预计会导致针尖看起来不太像斜尖针，而更像圆尖针，圆尖的高点偏离中心。

DESCRIPTION (provided by applicant): Accuracy of needle placement is a matter of fundamental importance in brain interventions such as tumor surgery and deep brain stimulation (DBS), and there is a need for improvements in order to increase efficacy of treatment. In response to this need, we have developed a computer-controlled system designed to steer a flexible needle through brain tissue, with proportional control of steering angle, using an elegantly simple technique of slowly rotating the needle in a "duty-cycled" fashion during insertion. The system can be used to reach targets deep in the brain, and can detour when needed in order to avoid damaging sensitive areas. Preliminary testing of the system has been performed in vitro in a gelatin substrate and in human cadavers. The testing that has been performed to date on this technology has focused solely on efficacy in reaching a particular target. There remain several unanswered needs, especially the development of means for tracking the tip of the flexible probe in vivo. However, before progressing to these questions, research is needed in several areas in order to ensure the safety of the technique. The specific aims of this proposal are as follows: 1. To adapt the tip geometry and the velocity envelope for safety in brain parenchyma. This will require finite element modeling of the needle tip geometry and the process of needle rotation in order to optimize the material, bevel angle, edge sharpness, rotation speed, and insertion speed of the probe in order to avoid damage to tissue. Results of the work will be validated in fresh animal brain tissue in vitro and then in vivo. 2. To adapt the tip geometry and the velocity envelope for safety in contact with blood vessels. This aim will involve testing in vivo in a porcine model, with comparisons to standard straight-sided biopsy needles, in order to validate the needle geometry, rotation speed, and insertion speed of the probe, to avoid damage to blood vessels that are contacted during insertion. The goal will be to limit the amount of bleeding detected via CT to that exhibited by present clinical straight-probe brain needle designs. 3. To optimize the design and the velocity envelope to avoid tissue damage along the length of the curved needle trajectory. Unlike a straight probe, insertion of a flexible needle of course places a certain amount of stress along the outer curvature of the needle path. Therefore, in addition to the above work dealing specifically with the needle tip, it will be necessary to model the interaction between the flexible needle and the tissue all along the shaft, optimizing the design of the needle gauge and the velocity envelope to avoid tissue damage along the trajectory. This work will also serve to prevent the possibility of any "whirling" or "whipping" motion of the tip of the flexible needle as the shaft is rotated. This work will be validated in animal tissue in vitro and then in a porcine model in vivo. These aims are expected to result in a needle tip that looks less like a bevel-tipped needle and more like a round-tipped needle with the high point of the round tip shifted off-center. PUBLIC HEALTH RELEVANCE: This research involves the development of improved techniques for reaching treatment sites deep in the brain, while causing minimal disturbance to surrounding healthy parts of the brain. It has the potential to improve treatment outcomes for cancer, Parkinson's disease, and other disorders.