Improving the spatial resolution of ultrasonic imaging using coded excitation

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DESCRIPTION (provided by applicant): The long term goal of the proposed research is to develop a new technology that will significantly improve the diagnostic capabilities of medical ultrasonic imaging and quantitative ultrasound (QUS) imaging. A novel technique, the resolution enhancement compression (REC) technique, is introduced that enables existing ultrasonic sources to increase their effective bandwidth, thereby improving axial resolution, and also providing a significant increase to the echo signal-to-noise ratio (eSNR). The technique does not require new ultrasonic sources to be constructed and could allow conventional transducers to compete with cMUT devices in terms of bandwidth. The innovations in this proposal will greatly improve conventional ultrasonic imaging by increasing the axial resolution and bandwidth of the system. The improved resolution will allow smaller structures to be imaged leading to improved diagnostic capabilities. In addition, the increase in eSNR leads to greater depth of penetration for ultrasonic imaging systems. Finally, the increased bandwidth can be used to further improve contrast resolution (CR) with frequency compounding techniques. Similarly, QUS imaging techniques would be greatly improved by larger bandwidth imaging systems. Larger bandwidth leads to smaller variance in spectral estimates (i. e. scatterer size) which in turn suggests that tissues will be more differentiable with QUS imaging techniques. Preliminary data suggests the approach is feasible, but a thorough testing of image quality through a set of quantifiable metrics must be examined to determine the true clinical benefits offered by the REC technique. To develop this technology for ultrasonic imaging and meet this long term goal two specific aims are proposed. The first specific aim is to examine the use of the REC technique to improve axial resolution, eSNR, and CR of conventional ultrasonic imaging. The improvement in conventional ultrasonic imaging through the REC technique will be quantified through several image quality metrics: the eSNR, modulation transfer function, CR through the contrast-to-noise ratio, and mainlobe-sidelobe ratios. The second specific aim is to quantify the improvement in spectral estimates of scatterer properties (QUS) using conventional pulsing techniques and the REC technique. The improvement in QUS imaging through the REC technique will be quantified through several quality metrics: the useable bandwidth, estimate variance, and estimate bias. Measurements on tissue mimicking phantoms with high and low contrast targets and simulations will be conducted using the REC technique and compared with measurements using conventional pulsing techniques. Effects of focusing, phase aberration and attenuation on performance of the REC technique will be quantified.