Fig. 7

The Velocity Contours on the Longitudinal Section at the systolic peak (t = 0.2 s). Pre-operatively, the blood flow velocity was rapid in the aneurysm sac without stagnation region. In the immediate post-operative period, the velocity in the sac become lower, and formed a stagnation region (V < 0.1 m/s). An obvious flow impingement region was observed in the remnant neck of the recanalized aneurysm. In the first follow-up, the flow impingement at the remnant neck of recanalized aneurysm became stronger and formed a wide area, while the stagnation area had reduced. In the second follow-up, the flow impingement became weaker than the previous follow-up and the impingement region became narrow, while the stagnation region enlarged. For the panel inside the image of Fig. 7, the red region on the top responds to high velocity, while the blue region at the bottom responds to low velocity