High contrast ultrasound imaging by motion-compensated time-averaging method

Motion-Compensated Time-Averaged Imaging (MTI), a method of accumulating frames with a motion compensation technique using small subregions was conducted to improve Power Doppler and B-mode imaging. In our previous study, MTI was shown to be able to clearly image vasculature with contrast agents without image blurring even if the target tissue was moving ^[1]. The purpose of this study is to investigate whether MTI is applicable to Power Doppler and B-mode imaging. It was found that image qualities improved in each case. The motion artifact of a Power Doppler image of rabbit kidney was reduced without blurring the image. Also, in the B-mode image of a human carotid artery, the inner membrane was clearly imaged, which is not possible with conventional imaging. The motion of carotid arteries in the slice direction leads to signal compounding at various angles in that direction and results in clear imaging without speckles. Although MTI is a powerful tool for improving ultrasound images, it incurs high computational costs because tissue motion must be compensated in every consecutive frame of an MTI image. As a feasibility test, we investigated whether we could carry out real-time MTI processing with a MAP processor (Equator technologies, inc.), which decreases computational cost. We estimated the cost of carrying out MTI with a MAP processor and found that it can be done at frame rates of up to 23 frames per second.