RESEARCH OUTPUT

Our group has been actively involved in the design of advanced imaging methods and signal processing strategies for both B-mode imaging and Doppler ultrasound. We also have a track record in the development of novel ultrasound systems and applications, as well as in the theoretical modeling of Doppler ultrasound signals. The following is a summary of our research output.

A) Synthetic Aperture Techniques

In attempt to improve the imaging quality, we have been exploring the use of synthetic aperture techniques for acquiring ultrasound images with better resolution (Yiu et al., Proc. IEEE Ultrason. Symp., 2008). Also, we have expanded this imaging paradigm to obtain vector flow estimates from the vasculature (Tsang et al., Proc. IEEE Ultrason. Symp., 2009b).

B) Pre-Beamform Data Acquisition System

To enable experimental evaluation of new imaging paradigms, our team has been developing a multi-channel pre-beamform data acquisition system that can be interfaced with the Sonix-RP research scanner (Tsang et al., Proc. IEEE Ultrason. Symp., 2009a). It should be the first of its kind commercially available to ultrasound system researchers.

C) Adaptive Flow Detection and Estimation

Another key imaging research topic that we have worked on is the design of advanced detection and estimation techniques for color Doppler imaging. We have designed eigen-based clutter filters that can help more reliably detect for blood flow in the presence of tissue motion (Yu and Cobbold, IEEE Trans. UFFC, 2008a), and have developed an eigen-based flow estimator that has more robust performance than the widely-used autocorrelation-based estimator (Yu and Cobbold, IEEE Trans. UFFC, 2008b).


In collaboration with NTNU in Norway, we have been investigating the performance of eigen-based clutter filters in various clinical imaging scenarios (Yu and Lovstakken, Proc. IEEE Ultrason. Symp., 2007, Lovstakken et al., Proc. IEEE Ultrason. Symp., 2007).

A) Carotid Pulse Assessment

Aside from our work in advanced ultrasound imaging, we are also active in designing novel ultrasound-based medical devices. For instance, with his Philips Research colleagues, Alfred has previously helped to develop an ultrasound-based carotid pulse checking device that is based on active sensing via Doppler principles (Yu et al., IEEE Trans. Biomed. Eng., 2008). It has shown potential in reliably monitoring a patient's resuscitation progress during cardiac arrest emergencies.

B) Osteogenesis Enhancement of Tissue-Engineered Cells

Together with the Tissue Engineering Lab at HKU, we have been investigating whether ultrasound can be used to accelerate the growth of tissue-engineered bone-like particles (Wong et al., Proc. IEEE Ultrason. Symp., 2009). We have shown that by applying low-intensity ultrasound exposure daily for the first few days in a three-week experimental period, an increase in the osteogenesis of the bone-like particles can be observed.

A) Spectral Broadening and Beam Steering Analysis

In addition to engineering developments in biomedical ultrasound, our group has strength in the theoretical modeling of ultrasound signals as well. As part of his graduate research, Alfred has proposed a novel signal model for pulsed Doppler signals based on generalized amplitude modulation principles (Yu et al., IEEE Trans. UFFC, 2006). He has also analyzed the effects of beam steering on the pulsed Doppler estimation accuracy when using commercial scanners to perform such diagnosis (Steinman et al., Ultrasound Med. Biol., 2005).

B) Color Doppler Signal Processing

We have demonstrated mastery on how signal processing can be performed in color Doppler imaging. Indeed, Alfred has been the primary author of a review article on the signal processing issues in color flow imaging (Yu et al., Can. Acoust., 2007). He has recently wrote another one in collaboration with NTNU in Norway (Yu and Lovstakken, IEEE Trans. UFFC, to-appear).