Department of Electronic Engineering, Fudan University, Shanghai, China.
Key Laboratory of Medical Imaging Computing and Computer Assisted Intervention (MICCAI) of Shanghai, Shanghai, China.
Biomed Eng Online. 2019 Apr 23;18(1):48. doi: 10.1186/s12938-019-0671-0.
Short-lag spatial coherence (SLSC) imaging, a newly proposed ultrasound imaging scheme, can offer a higher lesion detectability than conventional B-mode imaging. It requires a high focusing quality which can be satisfied by the synthetic aperture imaging mode. However, traditional nonadaptive synthesis for the SLSC still offers an unsatisfactory resolution. The spatial coherence estimation on the receive aperture cannot fully utilize the coherence information in two-dimensional (2D) echo data.
To overcome these drawbacks, an improved SLSC scheme with adaptive synthesis on dual apertures is proposed in this paper. The minimum variance (MV) beamformer is applied in synthesizing both the receiving and transmitting apertures, while the SLSC function is estimated on both apertures as well. In this way, the resolution is enhanced by the MV implementation, while the coherence in dual apertures is fully utilized.
Simulations, phantom experiments, and in vivo studies are conducted to evaluate the performance of the proposed method. Results demonstrate that the proposed method achieves the best performance in terms of the contrast ratio (CR), contrast-to-noise ratio (CNR), and the speckle signal-to-noise ratio (SNR). Specifically, compared with the delay-and-sum (DAS) method, the proposed method achieves 42.5% higher CR, 412.7% higher CNR, and 402.9% higher speckle SNR in simulations. The resolution is also better than the DAS and conventional SLSC beamformers.
The proposed method is a promising technique for improving the SLSC imaging quality and can provide better visualization for medical diagnosis.
短滞后空间相干（SLSC）成像是一种新提出的超声成像方案，与传统的 B 模式成像相比，它可以提供更高的病变检测能力。它需要高聚焦质量，这可以通过合成孔径成像模式来满足。然而，传统的 SLSC 非自适应合成仍然提供了不理想的分辨率。在接收孔径上的空间相干估计不能充分利用二维（2D）回波数据中的相干信息。
为了克服这些缺点，本文提出了一种带有双孔径自适应合成的改进 SLSC 方案。最小方差（MV）波束形成器应用于接收和发射孔径的合成，同时在两个孔径上估计 SLSC 函数。这样，通过 MV 实现来提高分辨率，同时充分利用双孔径中的相干性。
进行了模拟、体模实验和体内研究，以评估所提出方法的性能。结果表明，在所提出的方法中，对比度比（CR）、对比度噪声比（CNR）和散斑信号噪声比（SNR）方面的性能最佳。具体而言，与延迟求和（DAS）方法相比，所提出的方法在模拟中实现了 42.5%更高的 CR、412.7%更高的 CNR 和 402.9%更高的散斑 SNR。分辨率也优于 DAS 和传统的 SLSC 波束形成器。
所提出的方法是一种有前途的提高 SLSC 成像质量的技术，可以为医学诊断提供更好的可视化效果。
