Which ultrasound technique is used to assess blood flow in major arteries and veins?

• A. B-mode
• B. Doppler
• C. M-mode
• D. 3D imaging

Answer: (B)

Doppler ultrasound is the method that measures blood flow by detecting frequency shifts of the ultrasound waves as they reflect off moving red blood cells. This lets you determine flow direction, speed, and pattern, which is essential for evaluating arteries and veins for things like stenosis or occlusion. B-mode provides grayscale images of anatomy without flow information, M-mode tracks motion of structures over time but isn’t used to quantify flow, and 3D imaging focuses on reconstructing volume anatomy rather than assessing dynamic flow. Doppler can be used in different forms, such as color Doppler to show flow on top of anatomy and spectral Doppler to quantify velocity and obtain waveforms.