Patent ID: 7798968

Claim:
A method for determining frequency shift parameters relating to blood flow characteristics, comprising: obtaining a plurality of Doppler signals from ultrasonic echoes acquired from a patient during a first basic time interval using an ultrasonic Doppler device; determining a power spectral density of the Doppler signals acquired during the first basic time interval; analyzing the power spectral density of the Doppler signals to obtain one or more power spectral lines; calculating a noise threshold of the power spectral density of the Doppler signals acquired during the first basic time interval using a mean noise level of a previous basic time interval; calculating a mean noise level of the power spectral density of the first basic time interval using the mean noise level of the previous basic time interval, the power spectral density of the Doppler signals acquired during the first basic time interval, and the noise threshold; and determining frequency shift parameters relating to the blood flow characteristics corresponding to a selected one of the one or more power spectral lines using the mean noise level of the first basic time interval, the noise threshold, and the selected power spectral line, wherein the frequency shift parameters comprise a maximum frequency shift and a mean frequency shift, and wherein one or more of the frequency shift parameters determines a blood flow velocity.