Experimental study on transient flow patterns in simplified saccular intracranial aneurysm models using particle image velocimetry

囊状脑动脉瘤简化模型内瞬态流场特性的粒子图像测速技术(PIV)实验研究

The hemodynamics of intracranial aneurysm(IA)comprises complex transient flow patterns that affect its growth and rupture.Owing to the combined effects of geometrical factors and pulsatile flow conditions,the transient flow patterns in the IA are still unclear.The purpose of this work is to reveal the effect of the aspect ratio(AR,sac height/neck width)on the evolution of the internal flow patterns and the hemodynamics of the IA.We proposed an easy method to fabricate three simplified elastic IA models and measured the transient flow characteristics by using particle image velocimetry(PIV).Transient vortex structures in the IA modes during a cardiac cycle were systemically measured and many new flow phenomena were found,including the vortex morphology(size,structure,and core location),a high-speed jet,wall compliance effects,and three flow modes during retrograde flow phase.The results show that the AR of the IA affects the transient flow patterns as well as the wall shear stress(WSS)in complex ways.The results could deepen our understanding of the transient flow behaviors in IA and guide related clinical studies.

颅内动脉瘤(Intracranial aneurysm,IA)内复杂的瞬态流场特性对动脉瘤生长和破裂有重要影响.由于几何参数和流场脉动条件的共同影响,脑动脉瘤瞬态流场特性尚不清楚.为了揭示动脉瘤几何比率(AR,囊高/颈部宽度)对内部流场特性演化和血流动力学参数的影响,提出了一种基于液滴成型的新方法,制作了三个简化、弹性、囊状脑动脉瘤模型,利用粒子图像测速技术(Particle image velocimetry,PIV),开展了瞬态流场特性测速实验,系统研究了不同心动周期内的瞬态流场结构,包括涡胞形态(尺寸、形状和涡心位置等)、高速射流、壁面顺应性和三种逆流状态下的流动模式等。研究结果表明,脑动脉瘤几何比率对瞬态流场特性和壁面剪切应力的影响复杂,深化了对脑动脉瘤瞬态流场特性的认识,对相关临床研究有一定的指导价值.