A REAL-TIME SYSTEM FOR QUANTIFYING AND DISPLAYING 2-DIMENSIONAL VELOCITIES USING ULTRASOUND

This paper describes a system that has been developed for measuring tw o-dimensional velocities in real time using ultrasound. The instrument tracks interframe speckle pattern motion using a Sum-Absolute-Differe nce (SAD) algorithm in order to produce a vector map of 2D velocities. The system's parallel architecture allows calculation of approximatel y 20,000 vectors per second using the current tracking geometry. A pro grammable graphics processor encodes individual velocity vectors with color and displays them superimposed on the B-mode image in real time. In vitro tests indicate that the system can track velocities well ove r the Doppler aliasing limit in any direction in the scan plane with g reater than 94% accuracy. A color encoded image obtained from a flow p hantom highlights the system's ability to display lateral motion with uniform coloration, in contrast to the two-color display of current ul trasonic Doppler instruments.