• Dunsby, Chris
• Hansen-Shearer, Joseph
• Yan, Jipeng
• Lerendegui, Marcelo
• Huang, Biao
• Toulemonde, Matthieu
• Riemer, Kai
• Tan, Qingyuan
• Tang, Meng-Xing
• Tonko, Johanna
• Weinberg, Peter D.

Abstract

The row-column addressed array is an emerging probe for ultrafast 3-D ultrasound imaging. It achieves this with far fewer independent electronic channels and a wider field of view than traditional 2-D matrix arrays, of the same channel count, making it a good candidate for clinical translation. However, the image quality of row-column arrays is generally poor, particularly when investigating tissue. Ultrasound localisation microscopy allows for the production of super-resolution images even when the initial image resolution is not high. Unfortunately, the row-column probe can suffer from imaging artefacts that can degrade the quality of super-resolution images as `secondary' lobes from bright microbubbles can be mistaken as microbubble events, particularly when operated using plane wave imaging. These false events move through the image in a physiologically realistic way so can be challenging to remove via tracking, leading to the production of 'false vessels'. Here, a new type of rolling window image reconstruction procedure was developed, which integrated a row-column array-specific coherence-based beamforming technique with acoustic sub-aperture processing for the purposes of reducing `secondary' lobe artefacts, noise and increasing the effective frame rate. Using an {{in vitro}} cross tube, it was found that the procedure reduced the percentage of `false' locations from 26\% to 15\% compared to traditional orthogonal plane wave compounding. Additionally, it was found that the noise could be reduced by 7 dB and that the effective frame rate could be increased to over 4000 fps. Subsequently, {{in vivo}} ultrasound localisation microscopy was used to produce images non-invasively of a rabbit kidney and a human thyroid.

Topics

• impedance spectroscopy
• microscopy