Apparatus and methods are disclosed for the detection and imaging of ultrasonic contrast agents. Ultrasonic apparatus is provided for coherent imaging of ultrasonic contrast agents, and for detecting harmonic contrast agents. The inventive apparatus includes a dual display for simultaneously viewing a real time image which displays the location of the contrast agent and a triggered contrast image. Methods of contrast agent detection and imaging include the measurement of perfusion rate characteristics, multizone contrast imaging, multifrequency contrast imaging, tissue perfusion display, and high PRF contrast image artifact elimination.