Improving the Image Resolution in Diverging Wave Compounding Using the Sparse Arrays Method Combined with the Minimum Variance

In the field of ultrasound ultrafast imaging for biomedical applications, Diverging Wave Compounding (DWC) represents an emerging ultrasound modality and is gaining special attention in the research community. Among different applications, this modality presents the potential of trucking deepest moving structures in cardiac applications and transient elastography. The standard DWC is realized in larger arrays which lead to improved resolution at the cost of increased data size and the complexity of electronics to receive and perform fast data processing. Therefore, the Sparse Arrays (SA) method leads to reducing the number of receiving channels while producing high-quality images. In this work, we explore the abilities of the SA combined with the Minimum Variance (MV) to improve data rate while providing high-quality images in DWC. The simulated media of 22 scatterers was built using Field II and therefore, illuminated with different tilted DWC using a linear array L11-4v, 5.2 MHz and, the sampling frequency of 40.6 MHz. For adaptive processing, using the proposed methods, the emission was performed using different modes to sparsely activate the elements of the transducer. A total amount of 31 firing elements (FE) were taken as a reference when using the Delay and Sum (DAS) method. However, only three FE were considered for adaptive processing using the MV and the SA combined with the MV method (S-MV). The proposed beamformers were benchmarked for performance evaluation using the averaged Full Width at Half Maximum (FWHM) at both directions (i.e., lateral and axial). It was found that the spatial resolution provided by the S-MV65 is close or higher compared to that provided by DAS 31 FE. Moreover, the deeper scatterers were better resolved. The spatial resolution improved when compared to that provided by the standard DAS. The proposed methodology allows reducing the number of activated transducer elements and, therefore, the amount of data required to form the image while providing closer or superior spatial resolution.