1. A method for real-time analysis and measurement of variations in ultrasonic signals comprising the steps of: acquiring and storing a predetermined number ultrasonic image frames; updating the stored number of image frames with deletion of the oldest frame and inclusion of a new image frame; making the stored number of image frames available for digital data analysis; digitally analyzing the temporal evolution at each spatial coordinate in the stored ultrasonic image frames; storing the result of the temporal analysis as a non-binary indicator image; and displaying said non-binary indicator image on a display unit.