Lee C S, Frizzell L A
Department of Electrical and Computer Engineering, University of Illinois, Urbana 61801.
Ultrasound Med Biol. 1988;14(8):735-42. doi: 10.1016/0301-5629(88)90029-4.
The levels for hind limb paralysis from 1 MHz, continuous wave, unfocused ultrasound in the neonatal mouse were determined at 1 and 16 bars hydrostatic pressure and at 10 and 37 degrees C. Above a specific intensity level at each temperature, the exposure duration for paralysis of 50% of specimens exposed (t50) was found to be greater at 16 bars than at 1 bar suggesting a threshold for cavitational involvement. Using these results, the intensity thresholds for cavitation were found to be in the ranges of 120-150 W/cm2 and 53-74 W/cm2 at 10 degrees C and 37 degrees C, respectively. This temperature dependence is consistent with a cavitation mechanism. In addition, the t50 at 289 W/cm2 and 10 degrees C was measured as a function of hydrostatic pressure and showed that cavitation was suppressed at hydrostatic pressures above approximately 10 bars. This result and the intensity threshold for cavitation at 1 bar and 10 degrees C yielded similar values for the threshold negative total pressure for cavitation in the neonatal mouse.
在新生小鼠中，测定了1兆赫兹连续波非聚焦超声导致后肢麻痹的水平，测定条件为1巴和16巴静水压以及10摄氏度和37摄氏度。在每个温度下，高于特定强度水平时，发现50%受暴露标本出现麻痹的暴露持续时间（t50）在16巴时比在1巴时更长，这表明存在空化参与阈值。利用这些结果，发现在10摄氏度和37摄氏度时空化的强度阈值分别在120 - 150瓦/平方厘米和53 - 74瓦/平方厘米范围内。这种温度依赖性与空化机制一致。此外，测量了在289瓦/平方厘米和10摄氏度时t50作为静水压的函数，结果表明在静水压高于约10巴时空化受到抑制。该结果以及在1巴和10摄氏度时空化的强度阈值得出了新生小鼠中空化阈值负总压力的相似值。
