The contribution of wall shear stress insult to the growth of small unruptured cerebral aneurysms in longitudinal 3D-TOF-MRA.

Abstract Objective Aneurysm growth is a risk factor for rupture, however the detailed mechanism remains unclear. The present study was performed to identify whether hemodynamic insult could prompt small unruptured aneurysms to grow. Methods Six pairs of unruptured small ( 50% volume increase; n = 6) and an angiographic stable group (with ±10% volume changes; n = 6). Patient-specific computational fluid dynamic models were created and run under pulsatile flow conditions. Reverse reconstruction technique was used to simulate the status of before aneurysm generation. Relevant hemodynamic variables were calculated and compared between the two groups. Results In the enlarged group, wall shear stress (WSS) decreased from aneurysm neck to dome, whereas WSS at the aneurysm neck (58.68 ± 34.45 Pa) and body (52.68 ± 46.37 Pa) was significantly higher than the stable group (neck: 36.83 ± 18.20 Pa and body: 30.77 ± 18.85 Pa) (P  Conclusion Local elevated WSS to the arterial wall contributed to cerebral aneurysm generation, whereas turbulent flow patterns and elevated WSS at the aneurysm neck and body worked together to result in further growth of small aneurysms.