Ultrasound (US) imaging is a widely used modality since it is non-invasive, safe, portable and cost-effective. Clinical and pre-clinical imaging are two applications of this modality based on the frequency of operation. The advent of array transducer technology over the last two decades has contributed to significant improvement in the state-of-the-art in clinical imaging (center frequency~1-10 MHz). However, emergent healthcare demand of obtaining better quality images at higher frame rates, without increasing the system hardware complexity, is an active research interest. Contrary to clinical imaging, pre-clinical imaging (center frequency >20 MHz) is still in its infancy due to the challenges in manufacturing an array transducer having thin and small sized active elements. The current practice of mechanical articulation of a single US transducer element yields considerably limited image quality compared to imaging at clinical frequency.
Beamforming, being one of the most important components of US scanner, dictates the final reconstructed image quality. Recently, several non-linear beamformers were proposed to improve the resolution of final reconstructed image at the expense of low CNR. Apodization, which is a crucial stage in beamforming can improve the CNR in linear beamformers. Surprisingly, apodization techniques have not been developed for these non-linear beamformers.
In this work development of novel non-linear beamformers by incorporating apodization to improve the state-of-the-art in clinical imaging was done and it was shown that both the image quality (> 50 % improvement) and the frame rate (16 times improvement) can be enhanced simultaneously without any additional hardware requirements. The developed beamformers are integrated with novel acquisition schemes, like the minimum-redundancy synthetic aperture approach using only two elements, for pre-clinical imaging to improve the image quality considerably compared to the state-of-the-art without the need for multi-element transducer arrays. Also, the developed methodology was experimentally validated for imaging at high-frequency (20 MHz) and was shown that the image quality enhanced (> 60 % improvement) compared to the state-of-the-art with minimal need of additional hardware.
The developed methods and results from simulations and experiments on tissue-mimicking phantoms for clinical and pre-clinical imaging will be shared in this presentation.