Zhao Jinxin, Wang Yuanyuan, Yu Jinhua, Guo Wei, Zhang Shun, Aliabadi Saeid
1 Department of Electronic Engineering, Fudan University, Shanghai, China.
2 Key Laboratory of Medical Imaging Computing and Computer Assisted Intervention of Shanghai, Shanghai, China.
Ultrason Imaging. 2017 Jul;39(4):224-239. doi: 10.1177/0161734616688328. Epub 2017 Jan 9.
The short-lag spatial coherence (SLSC) imaging has been demonstrated to be advantageous over the traditional B-mode ultrasound imaging. With focused scanning beams, the SLSC imaging has an excellent performance in clutter reduction and lesion detection, especially in the low signal-to-noise ratio (SNR) scenarios. The synthetic aperture (SA) imaging is an appropriate mode for the SLSC imaging as the dynamic transmit focusing could keep a good focusing quality at any depth. However, the SLSC image may still suffer a bad resolution performance when a low lag value is used in the coherence summation to ensure the contrast enhancement. In this paper, an adaptive synthetic transmit (Tx) aperture focusing strategy is proposed for the SLSC imaging with the SA mode. Based on the achievements of adaptive beamforming, a minimum variance beamformer is applied in the Tx aperture to realize adaptive focusing. Spatial coherence is then measured in the receive aperture to form the SLSC image. Simulation and experimental studies were conducted to evaluate the proposed method. Experiments showed that the proposed method not only improved the poor resolution of the original SLSC image but also enhanced the speckle performance, which led to increased contrast-to-noise ratio and speckle SNR values.
短延迟空间相干（SLSC）成像已被证明比传统的B模式超声成像更具优势。通过聚焦扫描波束，SLSC成像在杂波抑制和病变检测方面具有出色的性能，尤其是在低信噪比（SNR）场景中。合成孔径（SA）成像适合SLSC成像，因为动态发射聚焦可以在任何深度保持良好的聚焦质量。然而，当在相干求和中使用低延迟值以确保对比度增强时，SLSC图像的分辨率性能可能仍然较差。本文针对SA模式的SLSC成像提出了一种自适应合成发射（Tx）孔径聚焦策略。基于自适应波束形成的成果，在Tx孔径中应用最小方差波束形成器以实现自适应聚焦。然后在接收孔径中测量空间相干性以形成SLSC图像。进行了仿真和实验研究以评估所提出的方法。实验表明，所提出的方法不仅改善了原始SLSC图像的低分辨率，还增强了散斑性能，从而提高了对比度噪声比和散斑SNR值。
