A New Signal Processing Method Based on Doppler Effect for Targeted Ultrasound Contrast Agent Imaging

Targeted ultrasound molecular imaging technology is emerging as a novel imaging modality that shows initial successes in sensitive detecting of inflammation, heart transplant rejection, thrombus and angiogenesis. In the targeted imaging, one challenge is to detect the signal from targeted contrast microbubles. The paper presents a new targeted contrast agent imaging method which could differentiate adherent and free agents effectively by using Doppler frequency shift. The Doppler frequency shift is employed to analysis the flowing bubble signal and stationary bubble signal. The Doppler shift frequency can be calculated due to the reflecting central frequency and bandwidth in addition to the velocity of the free bubble controlled by a syringe pump in the experiment. The wall filter is applied for filtering the signal that brings up the Doppler shift frequency. By using the method, experimental study shows compressed the free contrast agent and tissue signals while leaving the targeted bubble signal unaffected.