A real-time signal processing technique for ultrasonic imaging of tissue vibrations for localizing the source of a bruit in a 2D image with respect to the anatomy and/or for obtaining simultaneous information about vibrations and the underlying blood flow. The bruit can be quantitatively assessed using an ensemble of ultrasound echoes. Signal processing enables estimation of wall displacement and the display of time-resolved vibration spectrum. Vibrations are detected and color-coded according to their amplitude and frequency and overlaid on the B-mode and/or color-flow image in real time. Proposed vibration imaging algorithms use data acquired during conventional ultrasonic color-flow imaging and the clutter signal, normally suppressed in color-flow imaging, to detect and characterize tissue vibrations. Three vibration imaging algorithms based on parametric modeling of vibrations and other criteria distinguish between clutter, blood flow, and vibrations. The techniques are usable to detect, locate, image, and quantitatively grade stenoses in blood vessels.