How does a noninvasive vascular study via Doppler ultrasound help diagnose arterial occlusion?

• A. Visualizes the arterial lumen with high-detail CT.
• B. Measures blood flow velocity and waveforms; abnormal waveforms indicate stenosis or occlusion.
• C. Measures blood oxygen saturation in tissues.
• D. Replaces MRI in all cases.

Answer: (B)

Doppler ultrasound in this context is about assessing blood flow dynamics, not just anatomy. By using the Doppler effect, it measures how fast the blood cells are moving and shows waveforms that reflect the pattern of flow in the artery. This hemodynamic information reveals whether there is narrowing or a blockage.

In a healthy artery, the flow waveform is typically normal and pulsatile. With narrowing (stenosis), the velocity at the narrowed segment increases and the waveform can become dampened or irregular, sometimes with spectral broadening. If the artery is completely occluded, little or no flow is detected beyond the blockage. So, abnormal waveforms and reduced or absent flow point to stenosis or occlusion, making Doppler ultrasound a key noninvasive tool for diagnosing arterial occlusion.

Other imaging modalities like CT provide detailed anatomical images of the lumen but are not the same as Doppler flow assessment; tissue oxygen saturation measures are not about flow in vessels, and Doppler ultrasound does not replace MRI in all situations.