# Coherent Multi-Transducer Ultrasound Imaging

## TL;DR

This paper introduces a novel multi-transducer ultrasound imaging method that coherently combines data from multiple synchronized transducers to enhance image resolution and target detectability without external tracking.

## Contribution

It develops a framework for coherent data compounding from multiple transducers, improving ultrasound image quality without external localization devices.

## Key findings

- Lateral resolution improved from 0.67 mm to 0.18 mm.
- Contrast-to-noise ratio increased from 0.702 to 0.721.
- Method demonstrated successfully in 2-D phantom and free-hand experiments.

## Abstract

An extended aperture has the potential to greatly improve ultrasound imaging performance. This work extends the effective aperture size by coherently compounding the received radio frequency data from multiple transducers. A framework is developed in which an ultrasound imaging system consisting of $N$ synchronized matrix arrays, each with partly shared field of view, take turns to transmit plane waves. Only one individual transducer transmits at each time while all $N$ transducers simultaneously receive. The subwavelength localization accuracy required to combine information from multiple transducers is achieved without the use of any external tracking device. The method developed in this study is based on the study of the backscattered echoes received by the same transducer and resulting from a targeted scatterer point in the medium insonated by the multiple ultrasound probes of the system. The current transducer locations along with the speed of sound in the medium are deduced by optimizing the cross-correlation between these echoes. The method is demonstrated experimentally in 2-D using ultrasound point and anechoic lesion phantoms and a first demonstration of a free-hand experiment is also shown. Results demonstrate that the coherent multi-transducer imaging has the potential to improve ultrasound image quality, improving resolution and target detectability. Lateral resolution, contrast and contrast-to-noise ratio improved from 0.67 mm, -6.708 dB and 0.702, respectively, when using a single probe, to 0.18 mm, -7.251 dB and 0.721 in the coherent multi-transducer imaging case.