Non-invasive estimation of hyperthermia temperatures with ultrasound
Non-invasive estimation of hyperthermia temperatures with ultrasound
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DOI：
10.1080/02656730500159103
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发表时间：
2005-09-01
影响因子：
3.1
通讯作者：
Moros, EG
中科院分区：
文献类型：
--
作者：
Arthur, RM;Straube, WL;Moros, EG
超声波是一种有吸引力的温度监测方式，因为它是非电离的，方便，便宜，并具有相对简单的信号处理要求。如果可以识别、测量和校准与温度相关的超声参数，则该模态对于温度估计可能是有用的。使用超声波作为非侵入式温度计的最突出的方法利用（1）由于组织热膨胀和声速（SOS）的变化引起的回波偏移，（2）衰减系数的变化或（3）来自组织不均匀性的反向散射能量的变化。在过去的十年里，回声移位的使用受到了最多的关注。通过跟踪散射体积和测量接收到的回波的时移，研究人员已经能够从理论上和实验上预测在体模中感兴趣区域的温度，在体外和初步的体内研究中的孤立组织区域。一般温度监测的这种方法的局限性是SOS和热膨胀系数的先验知识是必要的。声衰减取决于温度，但只有在50摄氏度以上的温度下才会发生显著变化，这可能导致其在热消融治疗中的使用。然而，低于该温度范围的衰减的最小变化降低了其用于临床热疗的吸引力。后向散射能量变化的模型和测量表明，在临床热疗温度范围内，后向散射能量的变化取决于单个散射体或散射区域的性质。校准来自不同组织区域的背散射能量是这种方法的重要目标。所有的方法必须能够科普运动的图像特征的温度估计的基础上。确定可行的超声温度估计方法的关键步骤是其在体内测试期间的性能。
Ultrasound is an attractive modality for temperature monitoring because it is non-ionizing, convenient, inexpensive and has relatively simple signal processing requirements. This modality may be useful for temperature estimation if a temperature-dependent ultrasonic parameter can be identified, measured and calibrated. The most prominent methods for using ultrasound as a non-invasive thermometer exploit either (1) echo shifts due to changes in tissue thermal expansion and speed of sound (SOS), (2) variation in the attenuation coefficient or (3) change in backscattered energy from tissue inhomogeneities. The use of echo shifts has received the most attention in the last decade. By tracking scattering volumes and measuring the time shift of received echoes, investigators have been able to predict the temperature from a region of interest both theoretically and experimentally in phantoms, in isolated tissue regions in vitro and preliminary in vivo studies. A limitation of this method for general temperature monitoring is that prior knowledge of both SOS and thermal-expansion coefficients is necessary. Acoustic attenuation is dependent on temperature, but with significant changes occurring only at temperatures above 50 degrees C, which may lead to its use in thermal ablation therapies. Minimal change in attenuation, however, below this temperature range reduces its attractiveness for use in clinical hyperthermia. Models and measurements of the change in backscattered energy suggest that, over the clinical hyperthermia temperature range, changes in backscattered energy are dependent on the properties of individual scatterers or scattering regions. Calibration of the backscattered energy from different tissue regions is an important goal of this approach. All methods must be able to cope with motion of the image features on which temperature estimates are based. A crucial step in identifying a viable ultrasonic approach to temperature estimation is its performance during in vivo tests.