Noninvasive temperature estimation in tissue via ultrasound echo-shifts .1. Analytical model
Noninvasive temperature estimation in tissue via ultrasound echo-shifts .1. Analytical model
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DOI：
10.1121/1.417359
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发表时间：
1996-10-01
影响因子：
2.4
通讯作者：
Damianou, CA
中科院分区：
文献类型：
--
作者：
MaassMoreno, R;Damianou, CA
由高强度聚焦超声引起的组织中的温度变化导致穿过加热组织的回波的时间偏移。这些时间偏移是由声速分布的热致变化和组织内的热膨胀引起的，我们的分析模型将这些偏移与温度分布的变化联系起来。有人建议，这些关系可以被用来作为一种方法的非侵入性估计的组织内的温度。该模型表明，回波位移主要取决于平均速度的变化沿着的声学路径的回波和没有明确的信息的形状的速度分布是必需的。相比之下，组织热膨胀的影响很小，但在某些条件下可能很显著。该理论以及数值模拟还预测，时移具有作为温度的函数的近似线性行为。这表明可以确定用于温度预测的经验线性延迟-温度关系。它还表明，或者，在组织中的温度分布可以估计从沿沿着的声学path. In建议的系统中，低电平脉冲回波采样期间短暂的时间内，当高强度的超声波照射是关闭的，从而假设线性声学行为的回波延迟的分布。非线性后效和其他干扰限制这种方法的可能性进行了讨论。(C)1996年美国声学学会。
Temperature changes in tissue, caused by high-intensity focused ultrasound, cause time shifts in the echoes that traverse the heated tissue. These time shifts are caused by thermally induced changes in the distribution of the velocity of sound and by thermal expansion within the tissue, Our analytical model relates these shifts to changes in temperature distribution. It is proposed that these relationships can be used as a method for the noninvasive estimation of temperature within the tissue. The model shows that the echo shifts depend mostly on changes in the mean velocity along the acoustical path of the echoes and that no explicit information about the shape of the velocity distribution is required. The effects of the tissue thermal expansion are small in comparison, but may be significant under certain conditions. The theory, as well as numerical simulations, also predicts that the time shifts have an approximately linear behavior as a function of temperature. This suggests that an empirical linear delay-temperature relationship can be determined for temperature prediction. It is also shown that, alternatively, the distribution of temperature in the tissue can be estimated from the distribution of echo delays along the acoustical path. In the proposed system, low-level pulse echoes are sampled during brief periods when the high-intensity ultrasonic irradiation is off, and thus linear acoustic behavior is assumed. The possibility of nonlinear aftereffects and other disturbances limiting this approach is discussed. (C) 1996 Acoustical Society of America.