This study characterizes the Doppler signal from simulated microemboli of various sizes in blood mimicking fluid using spectral energy parameters. The goal of this research is to detect microemboli as a non-invasive diagnostic tool, or intra-operatively as a surgical aid. A dual beam diffraction-grating ultrasound probe operating at 10 MHz (Model Echoflow BVM-1, EchoCath, Inc., Princeton, NJ) was used with a flow phantom. Microemboli were polystyrene microspheres in 200 to 1000 micron diameters, in concentrations of 0.1, 0.5, and 1.0 per ml. Average flow velocities were 25, 50, 75, and 100 cm/sec. The distribution of peak values of the power spectrum at 2.5 msec windows was plotted over 15 seconds. The means of the distributions corresponding to the microspheres and background fluid were averaged for the four velocity conditions. Embolic peak spectral power ranged from approximately 12 to 25 dB relative to the background. A detection method based on these measurements is currently being developed.

Date Published: 23 May 2003
PDF: 9 pages
Proc. SPIE 5035, Medical Imaging 2003: Ultrasonic Imaging and Signal Processing, (23 May 2003); doi: 10.1117/12.479951

Published in SPIE Proceedings Vol. 5035:
Medical Imaging 2003: Ultrasonic Imaging and Signal Processing
William F. Walker; Michael F. Insana, Editor(s)