High resolution ultrasound imaging using adaptive beamforming with reduced number of active elements

In this paper, the adaptive, minimum variance (MV) beamformer is applied to ultrasound data. Due to near-field properties, the energy of the ultrasound data reduces towards the edges of the transducer. The influence of this near-field effect is demonstrated, and a method to reduce this influence is proposed. By reducing the number of active sensor elements, an increased resolution can be obtained with the MV beamformer. This observation is directly opposite the well-known relation between the spatial extent of the aperture and the achievable resolution. The investigations are based on Field II simulated data using a 128-element transducer with a large spatial extent. The results show that an increased resolution can be obtained, when using only the central part of the transducer compared to using the entire spatial extent. Using the central 32 or 48 elements provides an increased resolution compared to using all 128 elements.