The method SUper-Resolution ultrasound imaging using the Erythrocytes as targets (SURE) is fully non-invasive, and can reliably visualize vessels with sizes down to 50 µm (1/3 of the wavelength) from a few seconds of data acquisition. Ideally, the acquisition and display should be done in seconds, but this is a challenge since the processing of SURE images is computationally demanding. Graphics Processing Units (GPUs) are specialized for high-throughput parallel processing, and in this paper it was explored whether a NVIDIA GeForce RTX 3090 GPU can enable real-time processing of SURE images, meaning the processing can keep up with the imaging rate of 417 Hz, allowing for a live video feed, similar to conventional ultrasound imaging. In-vivo data was acquired from a Sprague-Dawley rat kidney with a 168 channel GE-L8-18iD 10 MHz linear array probe connected to a Verasonics Vantage 256 scanner at a 62.5 MHz sampling rate. The GPU was used to perform beamforming, motion correction, stationary echo cancellation and peak localization. The resulting processing rate was 475 Hz for the beamforming, and 497 Hz for the proceeding processing steps, resulting in a total rate of 239 Hz. Consequently, SURE images can now be acquired in 2 seconds, and shown approximately 1 second after this, making it possible to visualize super resolution images of the microvasculature at the bedside, for immediate diagnosis of the patient.

This work presents a beamforming procedure that significantly reduces the number of operations when performing volumetric synthetic aperture imaging with row-column addressed arrays (RCAs). The proposed beamformer uses that the image values along the elevation direction of the low-resolution volume (LRV) are approximately constant. It is thus hypothesized that the entire LRV could be reconstructed from a single 2-D cross-section of the LRV. The presented method contains two stages; The first stage beamforms, for each emission, a crosssection using the conventional RCA beamformer. The second stage extrapolates the rest of the image points in the volume from the 2-D cross-sections. Assuming the image volume is covered by 3-D grid coordinates with a size of Nw × Nw × Nz, i.e., Nw samples along the x-and y-axis and Nz samples along the z-axis, the proposed beamformer reduces the number of mathematical operations by a factor of approximately N Nw/(N S + Nw). Here S is the ratio between the first and second stage axial sampling rate, and N is the receiving aperture's number of channels. Beamforming a 128 × 128 × 1024 volume from data acquired with N = 128 receiving channel can thus be achieved with 25.6 times fewer operations, when S = 4.A 9.23 times increase in the beamforming rate for a 100 × 100 × 200 volume with S = 2 was demonstrated on complex data from a 128 + 128 Vermon RCA probe. Real-time volumetric beamformation can, with this increase, be performed with a pulse repetition frequency of up to 1804.80 Hz.The proposed and conventional beamformer's output was visually indistinguishable and, the full width at half maximum (FWHM) and full width at tenth maximum (FWTM) were at most 1.19% larger with the proposed approach.The proposed beamformer can thus perform volumetric imaging significantly faster than the current approach, with a negligible difference in image quality.

This work presents a beamforming procedure that significantly reduces the number of operations when performing volumetric synthetic aperture imaging with row-column addressed arrays (RCAs). The proposed beamformer uses that the image values along the elevation direction of the low-resolution volume (LRV) are approximately constant. It is thus hypothesized that the entire LRV could be reconstructed from a single 2-D cross-section of the LRV. The presented method contains two stages; The first stage beamforms, for each emission, a crosssection using the conventional RCA beamformer. The second stage extrapolates the rest of the image points in the volume from the 2-D cross-sections. Assuming the image volume is covered by 3-D grid coordinates with a size of Nw × Nw × Nz, i.e., Nw samples along the x-and y-axis and Nz samples along the z-axis, the proposed beamformer reduces the number of mathematical operations by a factor of approximately N Nw/(N S + Nw). Here S is the ratio between the first and second stage axial sampling rate, and N is the receiving aperture's number of channels. Beamforming a 128 × 128 × 1024 volume from data acquired with N = 128 receiving channel can thus be achieved with 25.6 times fewer operations, when S = 4.A 9.23 times increase in the beamforming rate for a 100 × 100 × 200 volume with S = 2 was demonstrated on complex data from a 128 + 128 Vermon RCA probe. Real-time volumetric beamformation can, with this increase, be performed with a pulse repetition frequency of up to 1804.80 Hz.The proposed and conventional beamformer's output was visually indistinguishable and, the full width at half maximum (FWHM) and full width at tenth maximum (FWTM) were at most 1.19% larger with the proposed approach.The proposed beamformer can thus perform volumetric imaging significantly faster than the current approach, with a negligible difference in image quality.