Phase and Amplitude Modulation Methods for Nonlinear Ultrasound Imaging With CMUTs.
Phase and Amplitude Modulation Methods for Nonlinear Ultrasound Imaging With CMUTs.
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使用 CMUT 进行非线性超声成像的相位和幅度调制方法。
DOI：
10.1109/tuffc.2016.2557621
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Degertekin,FLevent
中科院分区：
文献类型：
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作者：
Satir,Sarp;Degertekin,FLevent
用于非线性组织和超声造影剂的选择性成像的常规幅度和相位调制脉冲序列被设计用于线性行为的压电换能器。电容式微机械超声换能器（CMUT）的固有非线性，特别是在大信号操作期间，使得这些方法不适用。在本文中，我们提出了不同的脉冲序列的非线性成像是有效的小信号和大信号CMUT操作。对于小信号操作，提出了用于微泡和组织谐波成像的双脉冲幅度和相位调制方法，其中CMUT非线性通过分谐波激励来补偿。在大信号制度，使用非线性模型，我们首先表明，有一个简单的线性关系之间的相位产生的每个谐波失真分量和输入驱动信号。基于该观察，我们展示了使用N + 1个连续相位调制发射事件的脉冲序列，以提取未被CMUT非线性破坏的非线性造影剂回波内容的N个谐波。所提出的方法假设没有先验信息的传感器，因此，适用于任何CMUT。相位调制方法也适用于具有泰勒级数描述的非线性的压电换能器和系统，其中输入信号和谐波含量之间的相同相位关系是有效的。使用商业造影剂的原理实验的证明验证了CMUT的相位调制脉冲序列，在高度非线性的脉冲骤回模式和压电换能器中操作。
Conventional amplitude and phase modulated pulse sequences for selective imaging of nonlinear tissue and ultrasound contrast agents are designed for piezoelectric transducers that behave linearly. Inherent nonlinearity of capacitive micromachined ultrasonic transducers (CMUTs), especially during large-signal operation, renders these methods inapplicable. In this paper, we present different pulse sequences for nonlinear imaging that are valid for small- and large-signal CMUT operations. For small-signal operation, two-pulse amplitude and phase modulation methods for microbubble and tissue harmonic imaging are presented, where CMUT nonlinearity is compensated via subharmonic excitation. In the large-signal regime, using a nonlinear model, we first show that there is a simple linear relationship between the phases of each harmonic distortion component generated and the input drive signal. Based on this observation, we demonstrate a pulse sequence using N + 1 consecutive phase modulated transmit events to extract N harmonics of the nonlinear contrast agent echo content uncorrupted by CMUT nonlinearity. The proposed methods assume no a priori information about the transducer and, therefore, are applicable to any CMUT. The phase modulation method is also valid for piezoelectric transducers and systems with nonlinearities described by Taylor series where the same phase relationship between the input signal and the harmonic content is valid. The proof of principle experiments using a commercial contrast agent validates the phase modulated pulse sequences for CMUTs, operating in a highly nonlinear collapse-snapback mode and for piezoelectric transducers.