3D Noninvasive Temperature Estimation with Ultrasound

描述(申请人提供)：在癌症的热疗中，肿瘤被提升到细胞毒性温度(41-45oC)，以帮助控制它们。非侵入性温度成像将增强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，具有0.5oC的精度和1cm3的分辨率。对于这一目的，超声波是一种有吸引力的手段。其他人已经探索了声速、衰减和回声位置的变化，但尚未减少到临床实践。在这里，我们计划研究超声背向散射能量(CBE)随温度的变化，为判断该方法的精度和空间分辨率提供基础。此前，我们预测了某些亚波长散射体的CBE单调变化。我们测量的CBE值与我们在组织图像中的预测类似，这些组织图像中的明显轴向和横向运动得到了补偿。为了扩展R21资助的这项前期工作，我们计划如下：1)使用组织学研究验证我们的模型对单个散射体反向散射超声能量(CBE)随温度的变化，并通过开发一个有效的计算框架来扩展该模型，以从散射体集合的模拟图像估计依赖于温度的CBE；2)生成实验数据，以便在体外标本的3D和体内制备的2D中表征CBE作为温度的函数，同时识别依赖于成像系统的CBE效应；3)开发运动跟踪算法，对掩盖了CBE温度依赖性的真实和/或表观运动进行补偿，然后在运动补偿后的图像中校准CBE以进行温度估计。如果背向散射能量的变化可以用来准确和可靠地估计温度，那么这一好处可能对热疗、其他热疗和一般的超声成像都很重要。通过拟议的研究，在动物制剂中成功地进行CBE温度估计，将为最终在临床热疗中以非侵入性、方便和低成本的方式在软组织中生成3D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.