Microwave Induced Thermal Imaging

微波感应热成像

• 批准号: 6966329
• 负责人: Matthew O'Donnell
• 金额: $ 22.37万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-05 至 2007-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6966329
• 关键词: atherosclerotic plaque; bioengineering /biomedical engineering; biomedical equipment development; cardiovascular disorder diagnosis; cardiovascular imaging /visualization; clinical biomedical equipment; microwave radiation; noninvasive diagnosis; phantom model

DESCRIPTION (provided by applicant): Among all atherosclerotic lesions, vulnerable plaque is particularly lethal and its sudden rupture typically leads to intraluminal thrombus, directly linked to a variety of clinical manifestations such as stroke and acute coronary syndromes. These rupture-prone plaques usually consist of a large lipid-rich core in the central portion of the eccentrically thickened intima and a thin fibrous cap. Reliable, noninvasive imaging tools are needed to identify these potentially fatal plaques before their disruption. We have developed a technique, called microwave-induced thermal imaging (MITI), to image tissue dielectric and thermal properties with potentially high spatial and contrast resolution. Under a reasonable set of assumptions, the imaging parameter is simply the product of the microwave absorption coefficient (alpha) with the derivative of the sound speed with respect to temperature (lambda). Generally, water-bearing tissue can be easily distinguished from lipids based on lambda, which can be particularly valuable in plaque composition characterization and vulnerability assessment. Consequently, we rename MITI thermal strain imaging (TSI) to indicate our new focus on the imaging parameter lambda in the model. This also allows us to explore other energy delivery methods in addition to microwaves without degrading system performance. We propose to test TSI for high-risk plaque identification in peripheral arteries, especially the carotid. If successful, it will represent a high performance, cost-effective, noninvasive alternative to current techniques such as IVUS, OCT, ultrafast computed tomography (UFCT) and magnetic resonance imaging (MRI). This revised R21 application presents a plan to test TSI as a potentially noninvasive, simple, and cheap imaging tool providing information about arterial plaque vulnerability with high spatial and contrast resolution. It is the aim, therefore, of the work proposed here to address the following issues in detail. 1.) Construct a heating source fully integrated with an ultrasound imaging system to provide controlled energy delivery to tissue equivalent phantoms and excised tissue samples during routine ultrasound scanning. Both ultrasound and microwave heating sources will be investigated. 2.) Develop robust pulse sequence and data acquisition schemes for controlled heating with simultaneous ultrasonic imaging. 3.) Develop signal processing methods to remove the effects of unwanted tissue motion during TSI data acquisition. Like all high precision speckle tracking methods, TSI is susceptible to tissue motion artifacts. Methods must be developed to identify and minimize these artifacts. 4.) Demonstrate that TSI can separate water-bearing tissues from lipids in images similar to methods developed for magnetic resonance imaging but with high spatial resolution for peripheral vascular applications. 5.) Demonstrate on excised arterial samples that TSI can identify the lipid pool within an arterial plaque. The results of these preliminary experiments will test TSI as an imaging technique for vulnerable plaque detection. If it proves viable, we will develop an RO1 proposal to build an integrated imaging system combining ultrasound with a controlled heat source and explore the possibility of noninvasive, in vivo highrisk plaque identification in the carotid and other peripheral arteries.

描述（由申请人提供）： 在所有动脉粥样硬化病变中，易损斑块尤其致命，其突然破裂通常会导致腔内血栓，与中风和急性冠脉综合征等多种临床表现直接相关。这些易于破裂的斑块通常由偏心增厚的内膜中央部分的大的富含脂质的核心和薄的纤维帽组成。需要可靠的非侵入性成像工具来在这些潜在致命的斑块破裂之前识别出它们。 我们开发了一种称为微波诱导热成像 (MITI) 的技术，能够以潜在的高空间和对比度分辨率对组织介电和热特性进行成像。在一组合理的假设下，成像参数只是微波吸收系数 (alpha) 与声速相对于温度的导数 (lambda) 的乘积。一般来说，基于 lambda 可以轻松区分含水组织和脂质，这在斑块成分表征和脆弱性评估中​​特别有价值。因此，我们将其重命名为 MITI 热应变成像 (TSI)，以表明我们新的重点是模型中的成像参数 lambda。这也使我们能够探索除微波之外的其他能量传输方法，而不会降低系统性能。我们建议测试 TSI 来识别外周动脉（尤其是颈动脉）中的高风险斑块。如果成功，它将成为 IVUS、OCT、超快计算机断层扫描 (UFCT) 和磁共振成像 (MRI) 等当前技术的高性能、经济高效、无创替代方案。 修订后的 R21 申请提出了一项计划，测试 TSI 作为一种潜在的无创、简单且廉价的成像工具，以高空间和对比度分辨率提供有关动脉斑块脆弱性的信息。因此，这里提出的工作的目的是详细解决以下问题。 1.) 构建与超声成像系统完全集成的加热源，以在常规超声扫描期间向组织等效体模和切除的组织样本提供受控的能量输送。超声波和微波加热源都将被研究。 2.) 开发强大的脉冲序列和数据采集方案，用于通过同步超声成像控制加热。 3.) 开发信号处理方法以消除 TSI 数据采集过程中不需要的组织运动的影响。与所有高精度散斑跟踪方法一样，TSI 容易受到组织运动伪影的影响。必须开发方法来识别和最小化这些伪影。 4.) 证明 TSI 可以在类似于磁共振成像方法的图像中将含水组织与脂质分离，但具有针对外周血管应用的高空间分辨率。 5.) 在切除的动脉样本上证明 TSI 可以识别动脉斑块内的脂质池。 这些初步实验的结果将测试 TSI 作为易损斑块检测的成像技术。如果证明可行，我们将制定RO1提案，建立一个将超声波与受控热源相结合的集成成像系统，并探索颈动脉和其他外周动脉中非侵入性体内高风险斑块识别的可能性。