For magnetic resonance angiography, which type of sequence utilizes velocity-induced phase shifts for vascular signal?

Magnetic Resonance Angiography (MRA) employs various techniques to visualize blood vessels, and one of the methods that specifically utilizes velocity-induced phase shifts is known as phase contrast (PC) MRA. In PC MRA, the technique relies on the differences in the magnetic resonance signal due to the movement of blood. When blood flows through a magnetic field during an MRI scan, it experiences a phase shift in its MR signal based on its velocity.

This phase shift is detected and used to calculate blood flow velocity, which enhances the visualization of blood vessels against the surrounding tissue. It is particularly useful for assessing vascular conditions and flow dynamics in real-time, giving valuable information about the patency and health of the blood vessels.

The other techniques mentioned, such as Time-of-Flight (TOF) MRA, rely on different principles, like exploiting the difference in signal intensity based on the timing of radiofrequency pulses and gradients to capture flowing blood. Contrast-Enhanced (CE) MRA usually depends on the application of a contrast agent to enhance the vascular signal. Diffusion-weighted sequences focus on the random brownian motion of water molecules and are not specific to vascular signal imaging.

Thus, the unique feature of PC MRA is its application of