Seo Chi Hyung, Yen Jesse T
University of Southern California, Biomedical Engineering, Los Angeles, CA, USA.
IEEE Trans Ultrason Ferroelectr Freq Control. 2009 Feb;56(2):291-303. doi: 10.1109/TUFFC.2009.1038.
We have recently presented a new method to suppress side lobes and clutter in ultrasound imaging called dual apodization with cross-correlation (DAX). However, due to the random nature of speckle, artifactual black spots may arise with DAX-processed images. In this paper, we present one possible solution, called dynamic DAX, to reduce these black spots. We also evaluate the robustness of dynamic DAX in the presence of phase aberration and noise. Simulation results using a 5 MHz, 128-element linear array are presented using dynamic DAX with aberrator strengths ranging from 25 ns root-mean-square (RMS) to 45 ns RMS and correlation lengths of 3 mm and 5 mm. When simulating a 3 mm diameter anechoic cyst, at least 100% improvement in the contrast-to-noise ratio (CNR) compared with standard beamforming is seen using dynamic DAX, except in the most severe case. Layers of pig skin, fat, and muscle were used as experimental aberrators. Simulation and experimental results are also presented using dynamic DAX in the presence of noise. With a system signal-to-noise ratio (SNR) of at least 15 dB, we have a CNR improvement of more than 100% compared with standard beamforming. This work shows that dynamic DAX is able to improve the contrast-to-noise ratio reliably in the presence of phase aberration and noise.
我们最近提出了一种在超声成像中抑制旁瓣和杂波的新方法，称为互相关双窗技术（DAX）。然而，由于散斑的随机性，经DAX处理的图像可能会出现伪黑斑。在本文中，我们提出了一种可能的解决方案，称为动态DAX，以减少这些黑斑。我们还评估了动态DAX在存在相位畸变和噪声情况下的鲁棒性。给出了使用5MHz、128阵元线性阵列的仿真结果，采用动态DAX，其像差强度范围从25纳秒均方根（RMS）到45纳秒RMS，相关长度为3毫米和5毫米。在模拟直径为3毫米的无回声囊肿时，使用动态DAX与标准波束形成相比，除了在最严重的情况下，对比度噪声比（CNR）至少提高了100%。猪皮、脂肪和肌肉层用作实验像差。还给出了在存在噪声情况下使用动态DAX的仿真和实验结果。在系统信噪比（SNR）至少为15dB的情况下，与标准波束形成相比，我们的CNR提高了100%以上。这项工作表明，动态DAX能够在存在相位畸变和噪声的情况下可靠地提高对比度噪声比。
