High frame-rate and high resolution medical imaging using adaptive beamforming

Recently, significant improvement in image quality has been demonstrated by applying the minimum variance (MV) beamformer to medical ultrasound imaging. In this paper we show that the low sidelobe level and narrow beamwidth of the MV beamformer can be utilized, not only to increase resolution, but to enhance image quality in several ways: Fewer and wider transmit beams combined with increased number of parallel receive beams may be used to increase frame rate. We demonstrate that the resolution obtained using an MV beamformer is equal to a conventionally beamformed image of wire targets, using 1/4th of the number of transmit beams and four parallel receive beams, potentially increasing the frame-rate by a factor four. The enhanced resolution of the MV beamformer may also be utilized to decrease the number of focal zones required to form a high resolution image. We demonstrate better resolution using one focal zone with an MV beamformer, compared to full dynamic focus using DAS. Finally, we show that by lowering the frequency of the transmitted beam and beamforming the received data with the adaptive beamformer, increased depth of penetration is achieved without sacrificing lateral resolution.