Coded excitation plane wave imaging for shear wave motion detection.
Coded excitation plane wave imaging for shear wave motion detection.
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DOI：
10.1109/tuffc.2015.007062
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发表时间：
2015-07
期刊：
影响因子：
--
通讯作者：
Chen S
中科院分区：
文献类型：
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作者：
Song P;Urban MW;Manduca A;Greenleaf JF;Chen S
平面波成像由于其超快的成像帧速率和大视场（FOV）而极大地推进了剪切波弹性成像领域。然而，由于缺乏发射聚焦，平面波成像也具有降低的穿透性，这使得在深层组织和肥胖患者中使用平面波进行剪切波检测具有挑战性。本研究调查了在平面波成像中实施编码激励以进行剪切波检测的可行性，假设与传统超声信号相比，编码超声信号可以提供上级检测穿透力和剪切波信噪比（SNR）。研究了相位编码（巴克码）和频率编码（线性调频码）两种方法。第一个体模实验表明，编码脉冲的穿透增益约为2-4 cm。随后的两项体模研究表明，所有编码脉冲通过对小运动提供上级灵敏度和对弱超声信号的鲁棒性而优于传统的短成像脉冲。最后，对肥胖受试者（身体质量指数= 40）的体内肝脏病例研究证明了使用所提出的方法用于体内应用的可行性，并表明所有编码脉冲都可以提供比传统短脉冲更高的SNR剪切波信号。这些发现表明，通过使用编码激励剪切波检测，可以受益于平面波成像提供的超快成像帧速率和大视场，同时保持良好的穿透力和剪切波信号质量，这对于获得稳健的组织剪切弹性测量至关重要。
Plane wave imaging has greatly advanced the field of shear wave elastography thanks to its ultrafast imaging frame rate and the large field-of-view (FOV). However, plane wave imaging also has decreased penetration due to lack of transmit focusing, which makes it challenging to use plane waves for shear wave detection in deep tissues and in obese patients. This study investigated the feasibility of implementing coded excitation in plane wave imaging for shear wave detection, with the hypothesis that coded ultrasound signals can provide superior detection penetration and shear wave signal-to-noise-ratio (SNR) compared to conventional ultrasound signals. Both phase encoding (Barker code) and frequency encoding (chirp code) methods were studied. A first phantom experiment showed an approximate penetration gain of 2-4 cm for the coded pulses. Two subsequent phantom studies showed that all coded pulses outperformed the conventional short imaging pulse by providing superior sensitivity to small motion and robustness to weak ultrasound signals. Finally, an in vivo liver case study on an obese subject (Body Mass Index = 40) demonstrated the feasibility of using the proposed method for in vivo applications, and showed that all coded pulses could provide higher SNR shear wave signals than the conventional short pulse. These findings indicate that by using coded excitation shear wave detection, one can benefit from the ultrafast imaging frame rate and large FOV provided by plane wave imaging while preserving good penetration and shear wave signal quality, which is essential for obtaining robust shear elasticity measurements of tissue.