Fundamental concepts regarding sizing and discrimination of air bubbles and red cell aggregates using pulsed-Doppler ultrasound

The embolus to blood power ratio (EBR) model is briefly described, which predicts that emboli become more detectable as Doppler carrier frequency decreases and vessel diameter decreases. The EBR model indicates that the use of the backscattered power front the blood in the Doppler sample volume and the use of more than one carrier frequency will be useful in discriminating size and composition of an embolic signal. The EBR model is shown to provide both sizing and discrimination of red cell aggregates from air bubbles, using dual frequency interrogation of an embolus (1.6 and 2.4 Mhz).