Fourier Domain Beamforming for Medical Ultrasound

TL;DR

This paper introduces a Fourier domain beamforming method for medical ultrasound that significantly reduces sampling rates while maintaining image quality, enabling more efficient data acquisition and processing.

Contribution

It develops a Fourier domain beamforming approach that allows sub-Nyquist sampling, building on compressed sensing and Xampling techniques, to improve ultrasound imaging efficiency.

Findings

Achieves up to 1/25 reduction in sampling rate compared to standard methods

Maintains high-quality image reconstruction from fewer samples

Demonstrates effectiveness on in vivo cardiac ultrasound data

Abstract

Sonography techniques use multiple transducer elements for tissue visualization. Signals detected at each element are sampled prior to digital beamforming. The required sampling rates are up to 4 times the Nyquist rate of the signal and result in considerable amount of data, that needs to be stored and processed. A developed technique, based on the finite rate of innovation model, compressed sensing (CS) and Xampling ideas, allows to reduce the number of samples needed to reconstruct an image comprised of strong reflectors. A significant drawback of this method is its inability to treat speckle, which is of significant importance in medical imaging. Here we build on previous work and show explicitly how to perform beamforming in the Fourier domain. Beamforming in frequency exploits the low bandwidth of the beamformed signal and allows to bypass the oversampling dictated by digital implementation of beamforming in time. We show that this allows to obtain the same beamformed image as in standard beamforming but from far fewer samples. Finally, we present an analysis based CS-technique that allows for further reduction in sampling rate, using only a portion of the beamformed signal's bandwidth, namely, sampling the signal at sub-Nyquist rates. We demonstrate our methods on in vivo cardiac ultrasound data and show that reductions up to 1/25 over standard beamforming rates are possible.