Dual-mode Ultrasound Arrays for Image-Guided Surgery

描述(申请人提供)：这项研究的长期目标是开发双模超声阵列(DMUA)系统，用于使用高强度聚焦超声(HIFU)非侵入性治疗癌症肿瘤。这些DMUA系统将能够产生治疗性脉冲HIFU光束，用于局部破坏目标组织，并使用相同的阵列元素间歇性地实时成像目标区域及其周围。利用一台1 MHz的元件的压电复合型DMUA样机，我们论证了使用同一换能器进行成像和治疗的可行性。使用适当的现场模拟工具，我们建议开发设计程序，以允许同时优化成像和治疗的DMUA。此外，我们建议设计和构建实时波束形成和信号处理能力，以允许在现实的实时测试中使用DMUA系统。在计划进行体内动物试验之前，这将是一个必要的步骤。我们将集中精力开发基于图像的反馈，以帮助在存在组织异质性和强散射目标的情况下重新聚焦HIFU光束。这将允许使用DMUA系统对肝脏和肾脏等腹部器官的肿瘤进行非侵入性治疗(通过在存在肋骨的情况下重新聚焦)。此外，我们将开发参数成像方法，在应用治疗性HIFU剂量之前、期间和之后评估被治疗的组织。特别是，我们将研究在亚治疗性暴露于靶区的HIFU束期间成像局部吸收、灌流和粘弹性特性(剪切模数和剪切粘度)的可行性。这些参数成像方法将被开发用于基于DMUA的成像和用于图像制导的商用超声扫描仪。这对于更好地理解DMUA(可能)有限的带宽和波束形成能力所造成的限制是必要的。此外，如果超声要作为一种图像引导方式继续存在，那么定量超声成像仍然是必要的。我们设想，在拟议研究的资助期内，将开发一个完全可操作的、基于图像反馈的实时DMUA系统，并在体外进行全面测试。一旦这个系统到位，我们计划与临床同事建立合作，在体内测试这个系统，为有针对性的临床应用做准备。如果我们成功，我们的DMUA系统将至少为其他图像引导方式，如MRI、CT或诊断超声增加重要价值。然而，如果基于DMUA的图像质量能够达到可以确保定量空间准确成像的水平，那么DMUA系统将为图像引导手术提供一种独特的方法。具体地说，我们将拥有自我引导的治疗阵列，能够在病变形成之前、期间和之后评估靶区。基于图像的反馈将有助于最大化目标的治疗剂量，同时将可能与治疗性HIFU光束相互作用的介入关键组织结构的附带损害降至最低。这对于治疗性HIFU在肝和肾肿瘤中的非侵入性应用至关重要。公共卫生相关性：将开发新一代超声阵列系统，用于癌症和其他组织异常的非侵入性治疗。该系统的显著特点是能够将高强度聚焦超声(HIFU)传输到目标组织，并使用相同的阵列单元提供来自治疗体积的图像反馈。治疗坐标系和成像坐标系之间的内在配准将导致图像引导外科手术的新范式。空间精确的基于图像的反馈将在存在组织异质性和其他强散射障碍的情况下通过重新聚焦HIFU光束来提高治疗效率。此外，在应用HIFU之前、期间和之后，在治疗性HIFU射束的准确位置上的组织反应的参数成像提供了一个独特的机会来监测治疗的进展并潜在地评估其结果。

DESCRIPTION (provided by applicant): The long-term objective of this research is the development of dual-mode ultrasound array (DMUA) systems for the noninvasive treatment of cancer tumors using high intensity focused ultrasound (HIFU). These DMUA systems will be capable of generating therapeutic pulsed HIFU beams for localized destruction of targeted tissue and intermittently imaging the targeted region and it's surroundings in real- time using the same array elements. Using a piezocomposite 1-MHz 64-element DMUA prototype, we have demonstrated the feasibility of using the same transducer for imaging and therapy. Using appropriate field simulation tools, we propose to develop design procedures that will allow the simultaneous optimization of DMUAs for both imaging and therapy. Furthermore, we propose to design and build the real-time beamforming and signal processing capabilities to allow the use of DMUA systems in realistic real-time testing. This will be a necessary step before planning to perform in vivo animal testing. We will focus our efforts on the development of image-based feedback that will help refocus the HIFU beam in the presence of tissue heterogeneity and strongly scattering objects. This will allow the use of DMUA systems for the noninvasive treatment of tumors in abdominal organs such as liver and kidney (by refocusing in the presence of the ribs). In addition, we will develop parametric imaging methods to assess the treated tissue before, during, and after the application of therapeutic HIFU dose. In particular, we will investigate the feasibility of imaging local absorption, perfusion, and viscoelastic properties (shear modulus and shear viscosity) during sub-therapeutic exposure to HIFU beams at the target. These parametric imaging methods will be developed for both DMUA-based imaging and commercial ultrasound scanners for image guidance. This is necessary to provide better understanding of the limitations imposed by the (possibly) limited bandwidth and beamforming capabilities of DMUAs. In addition, quantitative ultrasonic imaging is still needed if ultrasound is to remain viable as an image-guidance modality. We envision a fully operational real-time DMUA system with image-based feedback will be developed and fully tested in vitro during the funding period of the proposed research. Once this system is in place, we plan to establish collaborations with clinical colleagues to test this system in vivo in preparation for targeted clinical applications. If we are successful, our DMUA system will add, at a minimum, significant value to other image-guidance modalities, e.g. MRI, CT, or diagnostic ultrasound. However, if the quality of DMUA- based images can be brought to levels where quantitative spatially accurate imaging can be assured, then DMUA systems will provide a unique approach to image-guided surgery. Specifically, we will have self- guided therapeutic arrays capable of assessing the target region before, during, and after lesion formation. The image-based feedback will help maximize the therapeutic dose at the target while minimizing collateral damage to intervening critical tissue structures that may interact with the therapeutic HIFU beam. This will be essential for the noninvasive application of therapeutic HIFU to liver and kidney tumors. PUBLIC HEALTH RELEVANCE: A new generation of ultrasound array systems for the noninvasive treatment of cancer and other tissue abnormalities will be developed. The distinguishing characteristic of the system is its capability to deliver high intensity focused ultrasound (HIFU) to the target tissue and provide image feedback from the treatment volume using the same array elements. The inherent registration between the therapeutic and imaging coordinate systems will lead to a new paradigm in image-guided surgery. Spatially accurate image- based feedback will improve the treatment efficacy by refocusing the HIFU beam in the presence of tissue heterogeneities and other strongly scattering obstacles. Furthermore, parametric imaging of the tissue response at the exact location of the therapeutic HIFU beam before, during, and after the application of HIFU provides a unique opportunity to monitor the progression of the treatment and potentially assess its outcome.