ULTRASONIC ATTENUATION AND VELOCITY IN FRESH PIG SOFT TISSUES IN VITRO

Ultrasonic attenuation and velocity were measured for six fresh pig tissues:blood vessel,brain,heart,liver,spleen and kidney by using the pulse insertion method. Frequency dependence of attenuation has been found to be nearly linear,with the power rangingfrom 0.96 to 1.39 over the 1—13 MHz at 37℃. Velocity dispersion has been observed for all of the six tissues and the average value was 0.11—O.38 m/s.MHz for frequency range from 5 to 13 MHz at 37℃. Temperature effect over the 7—37℃ range for brain was also studied.Velocity at 1 MHz wasfound to be of positive temperature coefficient with average value 1.3m/s·℃and attenuation at 1,3,5MHz decreased with increasing temperature. Velocity for six tissues studied was an approximately linear function of their whole protein content.Every unit protein percentage concentration raises velocity by about 2.9m/s at 5 MHz and 37℃.     

纹肌组织声速各向异性的研究

本文对一般紧密排列的圆柱形纤维结构的二元系统的声速各向异性问题进行了讨论。理论分析表明,对这种系统,不论纤维之间的充填媒质的弹性模量是否大于纤维本身的弹性模量,声波平行于纤维传播的声速总是大于垂直于纤维传播的声速。文章进而把理论分析用于讨论动物的纹肌组织,将纹肌组织看成是由肌纤维组织和肌纤维束膜结缔组织组成的二元体系。计算表明,平行于肌纤维传播声波的声速比垂直传播声速约大12m/s。这一结果为我们的实验数据及其它有关文献上报道的数据所证实,从而揭示了纹肌组织声速各向异性的物理本质。     

ANISOTROPY OF ULTRASONIC SPEED IN MUSCULAR TISSUES

In the present study,a simplified model is used to work out the anisotropy of sound speed in afiber bundle.First it explains qualitatively why the sound speed in the direction of fiber is greater thanthat in the direction perpendicular to the fiber.Them.it gives an estimation of the difference in speedThe estimation is in agreement with the experimental data.     

猪的新鲜离体软组织的超声衰减和速度

本文使用脉冲插入取代法测量了猪的6种新鲜软组织(血管、脑、肾、心、脾及肝)的超声衰减和传播速度。在37℃下,6种软组织的超声衰减系数a_s与频率a_s-f~n之间均满足幂函数关系。在所研究的l—13MHz频段内,n值在0.96—1.39之间。六种软组织的超声速度均表现出微量但颇为明显的频散现象,在5—13MHz频段内平均频散量为0.11—0.38m/s.在7一37℃温度范围内对脑组织超声衰减和传播速度的研究表明:声速(1MHz)随温度单调上升,变化趋势与水中声速类似。声衰减(1、3、5MHz)则随温度上升而下降,但对较低频率,下降的速度变缓。6种软组织的声速值(5MHz,37℃)近似地与它们各自的总蛋白含量成正比,蛋白含量每增加1％约使声速升高2.9m/s。