Which diagnostic modality would most directly measure flow through an abdominal aortic aneurysm by assessing velocity of blood flow?

• A. Doppler ultrasound velocity measurement
• B. CT angiography
• C. MRI spectroscopy
• D. X-ray fluoroscopy

Answer: (A)

Measuring how fast blood moves through an abdominal aortic aneurysm is most directly done with Doppler ultrasound. It uses the Doppler effect: sound waves transmitted from a transducer bounce off moving red blood cells, causing a frequency shift that is proportional to their velocity. This lets clinicians quantify flow velocity in real time, determine direction, and detect turbulent flow within the aneurysm.

CT angiography provides detailed anatomy and lumen images using contrast, but it does not give direct velocity data. MRI spectroscopy analyzes tissue chemistry rather than blood flow, and X-ray fluoroscopy shows motion with contrast but does not yield precise velocity measurements.