Microembolus Sizing in a Blood-Mimicking Fluid Using a Novel Dual-Frequency Pulsed Doppler.

Sizing of emboli in a blood-mimicking fluid is explored with the application of a theoretical description of emboli to embolic signatures obtained in a phantom flow loop. The theoretical predictions for the backscattered power versus embolus size are based on the embolus to blood power ratio (EBR) model. The experimental setup utilizes a customized ultrasound pulsed Doppler that is capable of interrogating a sample volume with two different frequencies concurrently. Polystyrene "emboli" having nominal diameters of 161 &mgr;m are placed in a specially constructed flow loop and scattering signatures are recorded. These signatures are investigated and the effect of beam refraction is discussed, which, combined with the EBR theory, yields a method to determine embolus size from an embolic signal. Embolus size determined experimentally is in close agreement with manufacturer's reported size. (ECHOCARDIOGRAPHY, Volume 13, September 1996)