Figure 3. Velocity pulsatility index (left) and area pulsatility index (right) per vessel for each segment showing inverse trends across segments for the velocity pulsatility and area pulsatility indices.

The area pulsatility decreases between C1 and C3, and subsequently increases again to C7, the velocity pulsatility increases between C1 and C3 and decreases again at C7. aPI indicates area pulsatility index; BA, basilar artery; ICA, internal carotid artery; and vPI, velocity pulsatility index.