ARTERIAL PROPERTIES FROM STIMULATED ACOUSTICAL EMISSION

组织的低频材料特性，如硬度或 流动性，已被证明与疾病有关， 动脉粥样硬化和肿瘤。 该计划的长期目标是 以产生用于测量和成像低频材料的方法， 使用高分辨率和高对比度的生物组织特性 我们新的超声激发声发射方法。 所得 动脉硬度的非侵入性测量将适合于研究 在人群中。在目前提出的方案中，我们追求的目标是 检测和成像切除内的钙化和非钙化斑块 动脉，并在动物模型中，使用成像技术， 声发射将物体的机械响应映射到局部 由干涉超声波束产生的循环辐射力。 的 我们的方法的新奇在于检测组织的诱导运动 通过其声发射导致对位移的敏感性， 几个安格利亚人的数量级 我们称之为“超声波”的方法 受激声发射（USAE）"，似乎非常适合于微 钙化和较少硬组织的检测和宏观检测。 该方法是由超声辐射压力刺激产生的， 使用双光束或共焦换能器几何形状的振动。 这 程序研究切除人类和体内猪动脉， 无疾病，比较USAE图像和光谱与组织学 动脉的分析。 初步结果清楚地描绘了 USAE图像中的钙化、非钙化和正常动脉节段 在7 kHz至41 kHz范围内的声发射频率下获得。 使用非侵入性仪器进行动脉粥样硬化的极早期检测 例如配备有超声激励的现代超声扫描仪 声发射，将提供一种有用的方法来描绘非 有症状的动脉粥样硬化患者， 没有这种系统性隐匿性疾病 成功完成本 该计划将导致USAE方法，立即适用于 临床研究。

Low-frequency material properties of tissues, such as stiffness or mobility, have been shown to be associated with diseases such as atherosclerosis and neoplasms. The long-term goal of this program is to produce methods for measuring and imaging low-frequency material properties of biologic tissues with high resolution and contrast using our novel ultrasound stimulated acoustic emission method. The resulting noninvasive measures of arterial stiffness would be amenable to studies in populations. In the currently proposed program we pursue the goal of detecting and imaging calcified and non-calcified placque within excised arteries, and in animal models, with an imaging technique that uses acoustic emission to map the mechanical response of an object to local cyclic radiation forces produced by interfering ultrasound beams. The novelty of our approach is that the induced motion of tissue is detected by its acoustic emission resulting in a sensitivity to displacement of the order of a few Angstroms. The method, which we call "Ultrasonic Stimulated Acoustic Emission (USAE)", appears well suited to both micro- detection and macro-detection of calcification and less hard tissues. The approach results from ultrasonic radiation pressure stimulation of vibration using dual beam or confocal transducer geometries. This program studies excised human and in vivo swine arteries, with and without disease, comparing USAE images and spectra to histologic analyses of the arteries. Preliminary results clearly delineate calcified, non-calcified, and normal arterial segments in USAE images obtained at acoustic emission frequencies ranging from 7 kHz to 41 kHz. Very early detection of atherosclerosis using a noninvasive instrument such as a modern ultrasound scanner equipped with ultrasonic stimulated acoustic emission, would provide a useful method of delineating non- symptomatic atherosclerosis patients with nascent disease from those without this systemic occult disease. Successful completion of this program will result in USAE methods that are immediately applicable to clinical studies.