Dual-mode Ultrasound Arrays for Image-Guided Surgery

描述（由申请人提供）：本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）对癌症肿瘤进行无创治疗。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件对目标区域及其周围环境进行实时间歇性成像。使用压电复合材料 1 MHz 64 元件 DMUA 原型，我们证明了使用相同换能器进行成像和治疗的可行性。我们建议使用适当的现场模拟工具开发设计程序，以便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成形和信号处理功能，以便在实际的实时测试中使用 DMUA 系统。这将是计划进行体内动物测试之前的必要步骤。我们将集中精力开发基于图像的反馈，这将有助于在存在组织异质性和强散射物体的情况下重新聚焦 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无创治疗（通过在肋骨存在的情况下重新聚焦）。此外，我们将开发参数成像方法来评估应用治疗 HIFU 剂量之前、期间和之后的治疗组织。特别是，我们将研究在亚治疗暴露于目标处的 HIFU 光束期间对局部吸收、灌注和粘弹性特性（剪切模量和剪切粘度）进行成像的可行性。这些参数化成像方法将针对基于 DMUA 的成像和用于图像引导的商用超声扫描仪而开发。为了更好地理解 DMUA（可能）有限的带宽和波束赋形功能所带来的限制，这是必要的。此外，如果超声要保持作为图像引导方式的可行性，则仍然需要定量超声成像。我们设想在拟议研究的资助期间，将开发一个具有基于图像反馈的完全可操作的实时 DMUA 系统，并在体外进行全面测试。一旦该系统到位，我们计划与临床同事建立合作，在体内测试该系统，为有针对性的临床应用做好准备。如果我们成功，我们的 DMUA 系统将至少为其他图像引导模式增加显着的价值，例如MRI、CT 或诊断超声。然而，如果基于 DMUA 的图像质量能够达到可以保证定量空间精确成像的水平，那么 DMUA 系统将为图像引导手术提供一种独特的方法。具体来说，我们将拥有能够在病变形成之前、期间和之后评估目标区域的自引导治疗阵列。基于图像的反馈将有助于最大限度地提高目标处的治疗剂量，同时最大限度地减少对可能与治疗性 HIFU 光束相互作用的关键组织结构的附带损害。这对于 HIFU 治疗肝脏和肾脏肿瘤的无创应用至关重要。 公共健康相关性：将开发用于癌症和其他组织异常的无创治疗的新一代超声阵列系统。该系统的显着特点是能够向目标组织传送高强度聚焦超声 (HIFU)，并使用相同的阵列元件从治疗区提供图像反馈。治疗坐标系和成像坐标系之间的固有配准将带来图像引导手术的新范例。基于空间精确图像的反馈将通过在存在组织异质性和其他强散射障碍物的情况下重新聚焦 HIFU 光束来提高治疗效果。此外，在应用 HIFU 之前、期间和之后，在 HIFU 治疗光束的确切位置对组织反应进行参数化成像，为监测治疗进展并可能评估其结果提供了独特的机会。

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.