Department of Electronic Engineering, Fudan University, Shanghai 200433, China.
Key Laboratory of Medical Imaging Computing and Computer Assisted Intervention (MICCAI) of Shanghai, Shanghai 200032, China.
Sensors (Basel). 2018 Nov 23;18(12):4099. doi: 10.3390/s18124099.
Plane wave compounding (PWC) is an effective modality for ultrafast ultrasound imaging. It can provide higher resolution and better noise reduction than plane wave imaging (PWI). In this paper, a novel beamformer integrating the two-dimensional (2-D) minimum variance (MV) with the generalized coherence factor (GCF) is proposed to maintain the high resolution and contrast along with a high frame rate for PWC. To specify, MV beamforming is adopted in both the transmitting aperture and the receiving one. The subarray technique is therefore upgraded into the sub-matrix division. Then, the output of each submatrix is used to adaptively compute the GCF using a 2-D fast Fourier transform (FFT). After the 2-D MV beamforming and the 2-D GCF weighting, the final output can be obtained. Results of simulations, phantom experiments, and in vivo studies confirm the advantages of the proposed method. Compared with the delay-and-sum (DAS) beamformer, the full width at half maximum (FWHM) is 90% smaller and the contrast ratio (CR) improvement is 154% in simulations. The over-suppression of desired signals, which is a typical drawback of the coherence factor (CF), can be effectively avoided. The robustness against sound velocity errors is also enhanced.
平面波复合（PWC）是一种用于超快超声成像的有效方法。与平面波成像（PWI）相比，它可以提供更高的分辨率和更好的降噪效果。在本文中，提出了一种新的波束形成器，将二维（2-D）最小方差（MV）与广义相干因子（GCF）相结合，以保持 PWC 的高分辨率和对比度以及高帧率。具体来说，在发射孔径和接收孔径中都采用 MV 波束形成。因此，子阵技术升级为子矩阵划分。然后，使用二维快速傅里叶变换（FFT）自适应地计算每个子矩阵的 GCF。完成二维 MV 波束形成和二维 GCF 加权后，即可获得最终输出。模拟、体模实验和体内研究的结果证实了该方法的优势。与延迟求和（DAS）波束形成器相比，在模拟中，全宽的 90%更小，对比度提高 154%。可以有效地避免相干因子（CF）的典型缺点，即对期望信号的过度抑制。对声速误差的鲁棒性也得到了增强。
