Multibeam minimum variance beamforming for ring array ultrasound imaging

Objective. Delay-and-sum (DAS) and minimum variance (MV) are two of the most important beamformers researched in ultrasound imaging. Compared with DAS, MV beamformer is different in respect of the aperture weights calculation, and can enhance the image quality by minimizing interference signal power. Various MV beamformers in linear array are studied, but linear array only provides a limited field of view. Ring array can provide better resolution and a full viewing angle; however, few studies have been explored based on ring array transducers.Approach. In this study, we proposed the multibeam MV (MB-MV) beamformer based on the conventional MV to enhance the image quality in ring array ultrasound imaging. To assess the effectiveness of the proposed approach, we conducted simulations, phantom experiments, andin vivohuman experiments to compare MB-MV with DAS and spatial smoothing (SS) MV beamformers.Main results. The results show that the MB-MV method achieves at least 50% enhancement in terms of full width at half maximum compared to the others. Additionally, the MB-MV method improves the contrast ratio by approximate 6 dB and 4 dB compared with DAS and SS MV, respectively.Significance. This work demonstrates the feasibility of MB-MV method for ring array ultrasound imaging, and proves that MB-MV can improve the imaging quality in medical ultrasound imaging. According to our results, MB-MV method provides great potential in distinguishing between lesion and non-lesion areas in clinics, and further promotes the practical application of ring arrays in ultrasound imaging.