Patent ID: 6261233
Filing Date: 2001-07-17
Classification: A61B

Abstract:
A method for determining a flow velocity of a flowing material suspended in a liquid and flowing in a conduit, comprising:irradiating the conduit with ultrasonic waves, wherein the conduit is a blood vessel;detecting first Doppler-shifted reflections of the waves from the flowing material, wherein the first Doppler-shifted reflections have a positive Doppler-shift;detecting second Doppler-shifted reflections of the waves from the flowing material, wherein the second Doppler-shifted reflections have a negative Doppler-shift;filtering at least one of the first and second reflections to provide a peak signal-amplitude, wherein the peak signal amplitude is substantially velocity independent to provide first and second reflection signals;generating a composite signal using the first and second reflection signals; andestimating the flow velocity as a function of the composite signal.