Department of Radiation Oncology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA.
Int J Hyperthermia. 2010;26(6):586-93. doi: 10.3109/02656731003801469.
To elucidate the causation mechanism of Spectral Doppler ultrasound signals (DUS) observed during high temperature thermal ablation and evaluate their potential for image-guidance.
Sixteen ex vivo ablations were performed in fresh turkey breast muscle, eight with radiofrequency ablation (RFA) devices, and eight with a conductive interstitial thermal therapy (CITT) device. Temperature changes in the ablation zone were measured with thermocouples located at 1 to 10 mm away from the ablation probes. Concomitantly, DUS were recorded using a standard diagnostic ultrasound scanner. Retrospectively, sustained observations of DUS were correlated with measured temperatures. Sustained DUS was arbitrarily defined as the Doppler signals lasting more than 10 s as observed in the diagnostic ultrasound videos captured from the scanner.
For RFA experiments, minimum average temperature (T1 +/- SD) at which sustained DUS were observed was 97.2 +/- 7.3 degrees C, while the maximum average temperature (T2 +/- SD) at which DUS were not seen was 74.3 +/- 9.1 degrees C. For CITT ablation, T1 and T2 were 95.7 +/- 5.9 degrees C and 91.6 +/- 7.2 degrees C, respectively. It was also observed, especially during CITT ablation, that temperatures remained relatively constant during Doppler activity.
The value of T1 was near the standard boiling point of water (99.61 degrees C) while T2 was below it. Together, T1 and T2 support the conclusion that DUS during high temperature thermal ablation are the result of boiling (phase change). This conclusion is also supported by the nearly constant temperature histories maintained at locations from which DUS emanated.
阐明高温热消融过程中所观察到的光谱多普勒超声信号（DUS）的产生机制，并评估其在影像引导中的潜在应用价值。
在新鲜火鸡胸脯肉中进行了 16 次离体消融实验，其中 8 次使用射频消融（RFA）设备，8 次使用传导间质热疗（CITT）设备。使用位于消融探针 1 至 10 毫米处的热电偶测量消融区域的温度变化。同时，使用标准诊断超声扫描仪记录 DUS。回顾性地，将 DUS 的持续观察与测量的温度相关联。DUS 的持续存在被任意定义为在从扫描仪捕获的诊断超声视频中观察到的持续超过 10 秒的多普勒信号。
对于 RFA 实验，观察到持续 DUS 的平均最低温度（T1 ± SD）为 97.2 ± 7.3°C，而未观察到 DUS 的平均最高温度（T2 ± SD）为 74.3 ± 9.1°C。对于 CITT 消融，T1 和 T2 分别为 95.7 ± 5.9°C 和 91.6 ± 7.2°C。还观察到，特别是在 CITT 消融期间，多普勒活动期间温度保持相对稳定。
T1 的值接近水的标准沸点（99.61°C），而 T2 低于该值。T1 和 T2 共同支持这样的结论，即高温热消融过程中的 DUS 是沸腾（相变）的结果。这一结论也得到了来自发出 DUS 的位置的温度历史几乎保持不变的支持。
