1975-2000: a quarter century of ultrasound technology.

The most popular forms of ultrasonic diagnostic technology experienced a major transition around 1975 with the introduction of real-time B-mode imaging and the combination of real-time imaging with pulsed Doppler in the Ultrasonic Duplex Scanner. At about the same time, the superposition of Doppler data as color on the gray-scale B-mode image was conceived and demonstrated. Since that time, the instruments have been commercialized and distributed broadly. Except for advancements in scanhead design, the introduction of dynamic focussing on echo receive, and conversion of the instruments from analog to digital processing, little has changed in ultrasound instruments; their size, price, features, and portability have been constant. A fully trained examiner using the most modern instrument made in 1978 can easily adapt the same examination methods to instruments made in 1990. The major change in ultrasound technology has been the increased application of ultrasound examination, specifically Doppler examinations to new organ systems. These trends will change in this final decade of the century. The comments here are from a perspective of noninvasive vascular diagnosis. Each of the advancements in ultrasound technology have resulted from the combined efforts and cooperation of many people. I will not attempt to credit those people here.