Color Doppler imaging of acoustic streaming in blood and clot

Acoustic streaming was generated in blood during coagulation using high intensity focused ultrasound (HIFU) and imaged in real-time with regular color Doppler imaging. The streaming velocity was measured at various time points during the coagulation process until a clot was well formed. In unclotted blood the mean streaming velocity was 3.8 cm/s. During the clot formation the velocity decreased gradually to 1.6 cm/s and the reverse flow disappeared entirely. The changes in velocity magnitude and flow pattern appear to provide a method to differentiate clots from fluidic blood and estimate the state of coagulation.