What is the normal post-injection PSV threshold?

• A. >40 cm/s
• B. >20 cm/s
• C. >30 cm/s
• D. >50 cm/s

Answer: (C)

Understanding how peak systolic velocity (PSV) behaves after a contrast or bolus injection helps interpret whether flow is within normal limits or suggestive of a problem. In this context, a normal post-injection PSV is around 30 cm/s. This value sits in the range that indicates typical, unobstructed arterial inflow after the bolus, reflecting a healthy, nonstenotic segment with normal pulsatile flow.

Velocities closer to 40–50 cm/s tend to imply increased flow velocity that can accompany a stenotic narrowing, while velocities much lower (e.g., around 20 cm/s) could reflect reduced inflow or poor perfusion. Since the scenario seeks the normal post-injection threshold, 30 cm/s is the best balance point that aligns with expected physiologic inflow after the injection.