Doppler ultrasonography, used to study vascular structure and the behavior of flowing blood, appeared in which decade?

• A. 1960s
• B. 1980s
• C. 2000s
• D. 1990s

Answer: (B)

Doppler ultrasonography uses the Doppler effect to detect motion of blood cells and measure their velocity, by noting shifts in the frequency of the reflected ultrasound. While the basic principle existed earlier, the imaging modality that combines this flow information with real-time anatomical imaging—duplex imaging, including color Doppler—became clinically available in the 1980s. That decade saw the introduction of practical scanners that could simultaneously show tissue anatomy and blood flow, allowing straightforward visualization of vascular structure and flow behavior. Subsequent decades improved resolution and added advanced techniques, but the appearance of Doppler ultrasonography as a widely used imaging tool is tied to the 1980s.