Ultrasound imaging system with intrinsic doppler capability

Abstract

An ultrasound imaging system capable of generating a flow image from B-mode echo frames. For each location in a target region, phase information is derived from the B-mode echo frames, and frame-to-frame changes in the phase information are processed to detect the presence of fluid flow at that location. A demodulator receives the B-mode echo frames and demodulates them into baseband signal components from which the phase information is derived. Preferably, the demodulator is highly accurate and robust, such that frame-to-frame changes in the phase information are reliably measured. From the reliably measured phase information, a phase shift metric is then computed and thresholded by a user-adjustable threshold value. Flow is present if the phase shift metric is greater than the threshold value and is absent otherwise. The user may adjust the threshold value in real time through an input device, such as a knob or keyboard, to increase or decrease the flow sensitivity as desired and/or to eliminate the slow-moving clutter. Together with a B-mode image, the flow image is provided to an ultrasound display. For further clutter removal, the flow image may be suppressed for those locations having B-mode intensities below a predetermined lower threshold or above a predetermined upper threshold. The provided system provides a real-time flow image having the same high frame rate, spatial resolution, and coverage area as the B-mode image.