Shankar P M, Dala Krishna P, Newhouse V L
Department of Electrical and Computer Engineering, Drexel University, Philadelphia, PA 19104, USA.
Ultrasound Med Biol. 1998 Mar;24(3):395-9. doi: 10.1016/s0301-5629(97)00262-7.
It is shown experimentally that backscatter from two ultrasonic contrast agents suspended in water or saline contains subharmonics of the incident frequency that are stronger than those backscattered at the same incident pressure from chicken breast. It is also shown that the ratio of subharmonic backscattered from contrast to that backscattered from tissue, is stronger than the ratio of backscattered second harmonic. In consequence, blood that contains contrast should be more easily detectable with respect to tissue if the subharmonic, rather than the second harmonic, is used for imaging.
实验表明，悬浮在水或盐水中的两种超声造影剂的反向散射包含入射频率的次谐波，这些次谐波比在相同入射压力下从鸡胸肉反向散射的次谐波更强。还表明，造影剂反向散射的次谐波与组织反向散射的次谐波之比，比反向散射的二次谐波之比更强。因此，如果使用次谐波而非二次谐波进行成像，相对于组织而言，含有造影剂的血液应该更容易被检测到。
