Photoacoustic (PA) imaging combining the advantages of high resolution of ultrasound imaging and high contrast of optical imaging provides images with good quality. PA imaging often suffers from disadvantages such as clutter noises and decreased signal-to-noise-ratio at higher depths. One studied method to reduce clutter noises is to use weighting factors such as coherence factor (CF) and its modified versions that improve resolution and contrast of images. In this study, we combined the Eigen-space based minimum variance (EIBMV) beamformer with the sign coherence factor (SCF) and show the ability of these methods for noise reduction when they are used in combination with each other. In addition, we compared the proposed method with delay-and-sum (DAS) and minimum variance (MV) beamformers in simulated and experimental studies. The simulation results show that the proposed EIBMV-SCF method improves the SNR about 94 dB, 87.65 dB, and 62.29 dB compared to the DAS, MV, and EIBMV, respectively, and the corresponding improvements were 79.37/34.43 dB, 77.25/26.96 dB, and 33.19/25.56 dB in the ex vivo/in vivo experiments.

中文翻译：

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基于特征空间的最小方差波束形成器结合符号相干因子：线阵光声成像的应用

光声 (PA) 成像结合了超声成像的高分辨率和光学成像的高对比度的优点，可提供高质量的图像。PA 成像通常存在一些缺点，例如杂波噪声和更高深度处的信噪比降低。一种减少杂波噪声的研究方法是使用加权因子，例如相干因子 (CF) 及其改进版本，以提高图像的分辨率和对比度。在本研究中，我们将基于特征空间的最小方差 (EIBMV) 波束成形器与符号相干因子 (SCF) 相结合，并展示了这些方法在相互结合使用时降噪的能力。此外，我们在模拟和实验研究中将所提出的方法与延迟求和 (DAS) 和最小方差 (MV) 波束形成器进行了比较。