Null Subtraction Imaging (NSI) is a novel beamforming technique that can produce B-mode images resulting in high spatial resolution and low computational cost compared to other beamforming techniques. Previous work has demonstrated that in addition to a beam pattern with a narrow main lobe and low side lobes, NSI can also reduce or mitigate grating lobes, which can appear when the array pitch is larger than one half the wavelength of the transmitted pulse. These grating lobes can result in imaging artifacts that produce clutter and lower contrast. By lowering grating lobe levels, a larger pitch array could be used, which could allow arrays with a larger field of view while maintaining a standard element count. This could have important benefits for specific applications such as ultrasonic abdominal imaging. Experiments were conducted to examine the feasibility of using NSI with large pitch, wide field-of-view arrays. Grating lobe reduction was measured against array pitch, DC offset, and f-number. Experiments were conducted on wire targets and contrast targets in a phantom and results were further verified in vivo by imaging the liver of a rabbit. The results demonstrated that NSI was able to reduce grating lobe brightness by up to 45 dB compared to delay-and-sum (DAS) beamforming when using planewave transmissions, reduce the generalized contrast-to-noise ratio (gCNR) of grating lobe regions from 0.60 to 0.08, and maintain a similar speckle quality to DAS. The gCNR of anechoic regions also improves, increasing from 0.09 to 0.15 on an array with a pitch of 5 wavelengths. Due to significant grating lobe level reduction, NSI shows potential to improve image quality over DAS on a large pitch, wide field-of-view array.

中文翻译：

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使用零减成像对大节距阵列进行光栅波瓣缓解

空减成像 (NSI) 是一种新颖的波束形成技术，与其他波束形成技术相比，它可以生成 B 模式图像，从而实现高空间分辨率和低计算成本。先前的工作已经证明，除了具有窄主瓣和低旁瓣的波束方向图外，NSI 还可以减少或减轻栅瓣，当阵列节距大于发射脉冲波长的一半时，就会出现栅瓣。这些光栅瓣会导致成像伪影，从而产生混乱和降低对比度。通过降低光栅波瓣水平，可以使用更大节距的阵列，这可以允许阵列具有更大的视场，同时保持标准元件数量。这对于超声腹部成像等特定应用具有重要的好处。进行了实验来检验使用具有大间距、宽视场阵列的 NSI 的可行性。根据阵列节距、直流偏移和光圈值测量光栅波瓣减小情况。在体模中的线目标和对比目标上进行了实验，并通过对兔子的肝脏成像在体内进一步验证了结果。结果表明，在使用平面波传输时，与延迟求和 (DAS) 波束形成相比，NSI 能够将光栅瓣亮度降低多达 45 dB，从而将光栅瓣区域的广义对比度噪声比 (gCNR) 降低0.60 至 0.08，并保持与 DAS 类似的散斑质量。消声区域的 gCNR 也有所改善，在间距为 5 个波长的阵列上从 0.09 增加到 0.15。由于栅瓣水平显着降低，NSI 显示出在大间距、宽视场阵列上比 DAS 提高图像质量的潜力。