Ultrasonic Duplex Echo-Doppler Scanner

Ultrasonic B-mode displays are produced by a new diagnostic scanner that yields dynamic Doppler information from blood flow in addition to both static and dynamic echo information from stationary and more slowly moving tissues. The effect is produced by combining the flow imaging capability of a multigate pulse-Doppler flow detector with a fast rotational pulse-echo B-mode scanner. The duplex system was designed for performing ultrasonic echo-Doppler arteriography where the location and geometry of the interface between occlusive atherosclerotic tissue and blood is of prime concern. Initial results on normal arteries in vivo are illustrated. Spatial alignment of echo and Doppler images is obtained by using the same transducer and scanning mechanism for both. However, clinical trials on patients with verified occlusive arterial disease indicated a two-transducer system would be more desirable. It is concluded that superposition of images of both tissue and blood decreases the uncertainties inherent in the display of either image alone.