Noninvasive Temperature Estimation with Ultrasound

描述(由申请人提供)： 热疗是一种肿瘤升高到细胞毒作用的癌症治疗方法。 温度(41-45摄氏度)，以帮助他们的控制。一种非侵入性方法 对于在治疗过程中以体积来确定温度分布 极大地增强了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温度图， 非侵入性、方便、低成本，具有0.5oC精度和1cm3 决议。对于这一目的，超声波是一种有吸引力的手段。中的更改 已经研究了声速、衰减和回声的位置 其他，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随温度的变化 为判断该模型的精度和空间分辨率提供了基础 接近。在我们的前期工作中，我们为变化开发了一个分析模型 在背向散射能量中与来自组织不均匀的温度 小(亚波长)散射体的形式。我们预测的变化在 背向散射能量与组织样本的体外测量结果相匹配。 尽管如此，使用我们的方法估计温度的能力仍然是一个 然而，这是一个高风险的命题，因为在以下方面仍然存在问题 能力：1)跟踪体外和体内的散射体；2)跟踪散射体 校准从它们接收到的能量的温度依赖关系 散布者。为了回答其中一些问题，我们计划研究各种 组织样本在体外，温度范围在37到50摄氏度。具体来说， 我们的目的是：1)测量和模拟背向散射超声的变化 来自个体散射体的能量，2)跟踪个体的位置 具有热膨胀和声速变化的散射体，以及3) 使用后向散射特性估计小体积的温度 感兴趣的体积中所有可分辨的散射体。如果中的更改 背向散射能量可以用来估计温度，好处可能是 对热疗、其他热疗和超声成像非常重要 将军。因为我们的方法利用了组织中存在的不均质性， 我们相信，如果它在体外成功；它有望在体内 申请。

DESCRIPTION (provided by applicant): Hyperthermia is a cancer treatment in which tumors are elevated to cytotoxic temperatures (41- 45 oC) in order to aid in their control. A noninvasive method for volumetrically determining temperature distribution during treatment would greatly enhance the ability to uniformly heat tumors at therapeutic levels. Our long-term goal is to produce three-dimensional temperature maps in soft tissue, noninvasively, conveniently, and at low cost, with 0.5 oC accuracy and 1 cm3 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 with temperature to provide a foundation for judging the accuracy and spatial resolution of this approach. In our preliminary work we developed an analytic model for the change in backscattered energy with temperature from tissue inhomogeneities in the form of small (subwavelength) scatterers. Our predicted changes in backscattered energy were matched by in vitro measurements in tissue samples. The ability to use our approach to estimate temperatures is nonetheless a high-risk proposition, however, because questions still exist with regard to the ability: 1) to track scatterers both in vitro and in vivo, and 2) to calibrate the temperature dependence of the energy received from these scatterers. To answer some of these questions, we plan to study a variety of tissue samples in vitro, over the 37 to 50 oC temperature range. Specifically, we intend: 1) to measure and model the change in backscattered ultrasonic energy from individual scatterers, 2) to track the position of individual scatterers with thermal expansion and changes in speed of sound, and 3) to estimate temperature over small volumes by using the backscatter properties of all the resolvable scatterers in the volume of interest. If changes in backscattered energy can used to estimate temperature, the benefits could be important for hyperthermia, other thermal therapies, and ultrasonic imaging in general. Because our approach exploits the inhomogeneities present in tissue, we believe that if it is successful in vitro; it holds promise for in vivo application.