Preliminary study of synthetic aperture tissue harmonic imaging on in-vivo data
A method for synthetic aperture tissue harmonic imaging is investigated. It combines synthetic aperture sequen-
tial beamforming (SASB) with tissue harmonic imaging (THI) to produce an increased and more uniform spatial
resolution and improved side lobe reduction compared to conventional B-mode imaging. Synthetic aperture
sequential beamforming tissue harmonic imaging (SASB-THI) was implemented on a commercially available BK
2202 Pro Focus UltraView ultrasound system and compared to dynamic receive focused tissue harmonic imag-
ing (DRF-THI) in clinical scans. The scan sequence that was implemented on the UltraView system acquires
both SASB-THI and DRF-THI simultaneously. Twenty-four simultaneously acquired video sequences of in-vivo 
abdominal SASB-THI and DRF-THI scans on 3 volunteers of 4 different sections of liver and kidney tissues were
created. Videos of the in-vivo scans were presented in double blinded studies to two radiologists for image quality
performance scoring. Limitations to the systems transmit stage prevented user defined transmit apodization to
be applied. Field II simulations showed that side lobes in SASB could be improved by using Hanning transmit
apodization. Results from the image quality study show, that in the current configuration on the UltraView
system, where no transmit apodization was applied, SASB-THI and DRF-THI produced equally good images.
It is expected that given the use of transmit apodization, SASB-THI could be further improved.