生物组织成像中用反相位脉冲技术提高二次谐波信噪比的研究

SNR enhancement for the second harmonics in tissue imaging by the use of the pulse inversion technique

本文基于有限振幅声波在介质中的非线性传播理论,分析了反相位脉冲技术对生物组织中二次谐波增强的原理。实验中利用反相位脉冲激发超声换能器,对生物组织中传播的非线性信号相加分析。结果表明反相位脉冲技术可有效抑制基波及奇次谐波信号,而可增强偶次谐波信号6dB。与滤波器滤波法相比,反相位脉冲技术在抑制基波信号的同时,可有效地提高二次谐波的信噪比,因而在生物组织的二次谐波成像中具有广阔的应用前景。

Enhancement of the second harmonic signal in biological tissues with the pulse inversion technique is herein analyzed, based on the theory of the finite amplitude sound wave. in the experiments, two inverted modulated burst signals are used to excite the transmitting transducer. After adding the received signals, the fundamental and the odd order harmonic components are effectively suppressed while the even order harmonic components are enhanced by 6dB. Compared with the traditional filter technique, the pulse inversion technique can enhance the signal to noise ratio of the second harmonic component, and thus will provide potential application in the second harmonic imaging of biological tissues.