3D Noninvasive Temperature Estimation with Ultrasound

描述（由申请人提供）：在癌症的热疗治疗中，将肿瘤升高到细胞毒性温度（41 - 45℃）以帮助其控制。无创温度成像将提高在治疗水平上均匀加热肿瘤的能力。我们的长期目标是在软组织中制作三维（3D）温度图，无创，方便，低成本，精度为0.5℃，分辨率为1cm3。超声是一种有吸引力的治疗方法。其他人已经对声速、衰减和回声位置的变化进行了探索，但尚未用于临床实践。本文拟研究超声背散射能量随温度的变化，为判断该方法的精度和空间分辨率提供依据。以前，我们预测了某些亚波长散射体的CBE单调变化。我们已经测量了CBE值类似于我们的预测，在图像中补偿了明显的轴向和横向运动的组织。为了扩展这项由R21资助的初步工作，我们计划如下：1)使用组织学研究验证我们的模型，用于单个散射体的温度依赖变化的后向散射超声能量（CBE），并通过开发一个有效的计算框架来扩展它，用于从散射体集合的模拟图像中估计温度依赖的CBE；2)生成实验数据，以便将体外标本的三维和体内制剂的二维CBE表征为温度的函数，同时确定依赖于成像系统的CBE效应；3)开发运动跟踪算法，以补偿掩盖CBE对温度依赖性的真实和/或表观运动，然后在运动补偿图像中校准CBE以进行温度估计。如果后向散射能量的变化可以用来准确可靠地估计温度，那么它对热疗、其他热疗法和超声波成像的好处可能是重要的。通过本研究在动物制剂中成功进行CBE体内温度估计，将为最终在临床热疗中以无创、方便、低成本的方式生成软组织三维温度图奠定基础。

DESCRIPTION (provided by applicant): In hyperthermia treatment of cancer, tumors are elevated to cytotoxic temperatures (41 - 45oC) in order to aid in their control. Noninvasive temperature imaging would enhance the ability to uniformly heat tumors at therapeutic levels. Our long-term goal is to produce 3-dimensional (3D) temperature maps in soft tissue, noninvasively, conveniently, and at low cost, with 0.5oC accuracy and 1cm3 resolution. Ultrasound is an attractive modality for this purpose. Changes in speed of sound, attenuation, and the location of echoes have been explored by others, but as yet not reduced to clinical practice. Here we plan to investigate changes in ultrasonic backscattered energy (CBE) with temperature to provide a foundation for judging the accuracy and spatial resolution of this approach. Previously, we predicted monotonic changes in CBE for certain sub wavelength scatterers. We have measured CBE values similar to our predictions in images of tissue that were compensated for apparent axial and lateral motion in the images. To extend this preliminary work performed with R21 funding we plan the following: 1) to validate our model for the temperature-dependent change in backscattered ultrasonic energy (CBE) from individual scatterers using histological studies, and to extend it by developing an efficient computational framework for estimating temperature-dependent CBE from simulated images of collections of scatterers; 2) to generate experimental data in order to characterize CBE as a function of temperature in 3D from ex vivo specimens and in 2D from in vivo preparations while identifying CBE effects that are dependent on the imaging system; and 3) to develop motion tracking algorithms to compensate for real and/or apparent motion that obscures the temperature dependence of CBE then calibrate CBE in motion-compensated images for temperature estimation. If changes in backscattered energy can be used to estimate temperature accurately and reliably, the benefits could be important for hyperthermia, other thermal therapies, and ultrasonic imaging in general. In vivo success of CBE temperature estimation in animal preparations through the proposed studies will serve as the foundation for the eventual generation of 3D temperature maps in soft tissue in a noninvasive, convenient, and low-cost way in clinical hyperthermia.