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系统将能够使用相同的阵列元件产生用于靶组织的局部破坏的治疗性脉冲HIFU射束，并且间歇地对靶区域及其周围环境进行真实的实时成像。使用压电复合1 MHz 64元件DMUA原型，我们已经证明了使用相同的换能器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，将允许同时优化DMUAs成像和治疗。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。这将是计划进行体内动物试验之前的必要步骤。我们将集中精力发展基于图像的反馈，这将有助于在组织异质性和强散射物体的存在下重新聚焦HIFU束。这将允许使用DMUA系统对腹部器官（如肝脏和肾脏）中的肿瘤进行非侵入性治疗（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，以评估治疗性HIFU剂量应用之前，期间和之后的治疗组织。特别是，我们将调查的可行性成像局部吸收，灌注，和粘弹性（剪切模量和剪切粘度）亚治疗暴露于HIFU束在目标。这些参数成像方法将被开发用于基于DMUA的成像和用于图像引导的商业超声扫描仪。这是必要的，以提供更好地理解的限制所施加的（可能）有限的带宽和波束成形能力的DMUA。此外，如果要使超声作为一种图像引导方式保持可行性，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的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。如果我们取得成功，我们的DMUA系统将至少为其他图像引导模式（例如MRI、CT或诊断超声）增加重要价值。然而，如果基于DMUA的图像的质量可以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独特的方法。具体来说，我们将有自我引导的治疗阵列，能够评估之前，期间和之后的病变形成的目标区域。基于图像的反馈将有助于最大化目标处的治疗剂量，同时最小化对可能与治疗性HIFU射束相互作用的介入关键组织结构的附带损伤。这将是必要的非侵入性应用治疗性HIFU肝和肾肿瘤。 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）输送到靶组织，并使用相同的阵列元件从治疗体积提供图像反馈。治疗坐标系和成像坐标系之间的固有配准将导致图像引导手术的新范例。空间精确的基于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射束来提高治疗功效。此外，在应用HIFU之前、期间和之后，在治疗性HIFU束的确切位置处对组织反应进行参数成像，提供了监测治疗进展并可能评估其结果的独特机会。

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.