Towa Rene T, Miller Rita J, Frizzell Leon A, Zachary James F, O'Brien William D
Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 61801, USA.
IEEE Trans Ultrason Ferroelectr Freq Control. 2002 Oct;49(10):1411-20. doi: 10.1109/tuffc.2002.1041082.
Attenuation coefficient and propagation speed of intercostal tissues were estimated as functions of temperature (22, 30, and 37 degrees C) from fresh chest walls from eight 10- to 11-week-old female Sprague-Dawley (SD) rats, eight 21- to 24-week-old female Long-Evans (LE) rats, and ten 6- to 10-week-old mixed sex Yorkshire (York) pigs. The primary purpose of the study was to estimate the temperature dependence of the intercostal tissue's attenuation coefficient so that accurate estimates of the in situ (at the pleural surface) acoustic pressure levels could be made for our ultrasound-induced lung hemorrhage studies. The attenuation coefficient of intercostal tissue for both species was independent of the temperature at the discrete frequencies of 3.1 MHz (-0.0076, 0.0065, and 0.016 dB/cm/degrees C for SD rats, LE rats, and York pigs, respectively) and 6.2 MHz (-0.015, 0.014, and 0.014 dB/cm/degrees C for SD rats, LE rats, and York pigs, respectively). However, the temperature-dependent regressions yielded a significant temperature dependency of the intercostal tissue attenuation coefficients in SD and LE rats (over the 3.1 to 9.6 MHz frequency range); there was no temperature dependency in York pigs (over the 3.1 to 8.6 MHz frequency range). There was no significant temperature dependency of the intercostal tissue propagation speed in SD rats; there was a temperature dependency in LE rats and York pigs (-0.59, -1.6, and -2.9 m/s/degrees C for SD rats, LE rats, and York pigs, respectively). Even though the attenuation coefficient's temperature dependency was significant from the linear regression functions, the differences were not very great (-0.040 to -0.13, 0.011 to 0.18, and 0.055 to 0.10 dB/cm/degrees C for SD rats, LE rats, and York pigs, respectively, over the data frequency range). These findings suggest that it is not necessary to determine the attenuation coefficient of intercostal tissue at body temperature (37 degrees C), but rather it is sufficient to determine the attenuation coefficient at room temperature (22 degrees C), a much easier experimental procedure.
从8只10至11周龄的雌性斯普拉格-道利（SD）大鼠、8只21至24周龄的雌性长-伊文斯（LE）大鼠以及10只6至10周龄的混合性别的约克郡（York）猪的新鲜胸壁中，估计肋间组织的衰减系数和传播速度作为温度（22、30和37摄氏度）的函数。该研究的主要目的是估计肋间组织衰减系数对温度的依赖性，以便能够为我们的超声诱导肺出血研究准确估计原位（在胸膜表面）声压水平。两种动物肋间组织的衰减系数在3.1 MHz（SD大鼠、LE大鼠和York猪分别为-0.0076、0.0065和0.016 dB/cm/摄氏度）和6.2 MHz（SD大鼠、LE大鼠和York猪分别为-0.015、0.014和0.014 dB/cm/摄氏度）的离散频率下与温度无关。然而，温度依赖性回归显示SD大鼠和LE大鼠的肋间组织衰减系数存在显著的温度依赖性（在3.1至9.6 MHz频率范围内）；York猪不存在温度依赖性（在3.1至8.6 MHz频率范围内）。SD大鼠肋间组织的传播速度不存在显著的温度依赖性；LE大鼠和York猪存在温度依赖性（SD大鼠、LE大鼠和York猪分别为-0.59、-1.6和-2.9 m/s/摄氏度）。尽管从线性回归函数来看衰减系数的温度依赖性显著，但差异并不是很大（在数据频率范围内，SD大鼠、LE大鼠和York猪分别为-0.040至-0.13、0.011至0.18和0.055至0.10 dB/cm/摄氏度）。这些发现表明没有必要在体温（37摄氏度）下测定肋间组织的衰减系数，而是在室温（22摄氏度）下测定就足够了，这是一个容易得多的实验程序。
