Which technique is specifically used to visualize the direction of blood flow?

Doppler ultrasound is specifically designed to visualize the direction and velocity of blood flow within vessels. This technique utilizes the Doppler effect, where sound waves emitted by the ultrasound transducer shift in frequency when they reflect off moving red blood cells. By analyzing these frequency changes, the system can determine both the speed and direction of blood flow, which is crucial for identifying abnormalities such as stenosis or thrombosis.

The other techniques listed, while valuable in medical imaging, do not possess the same capabilities for assessing blood flow direction. Echocardiography primarily focuses on the structure and function of the heart, providing images of heart chambers and valves rather than detailed flow dynamics. Computed tomography is generally utilized for providing cross-sectional images of the body and is not specifically designed for flow evaluation. Magnetic resonance imaging produces detailed anatomical images and can sometimes assess flow through techniques like phase contrast MRI, but it is not as direct or standard for blood flow visualization compared to Doppler ultrasound.