1	Virtual Simulation of Particle Imaging Velocity in cerebral aneurysm Takao, H.¹ Murayama, Y.¹ Saguchi, T.¹ Ishibashi, T.¹ Ebara, M.¹ Irie, K.¹ Harada, T.² Qian, Y.² Umezu, M.² Abe, T.¹ ¹The Jikei University School of Medicine, Tokyo, JAPAN ²Waseda University, Tokyo, JAPAN
2	Purpose Hemodynamic factors play an important role in initiation, growth, and rupture of cerebral aneurysm. However, it is difficult to evaluate this phenomenon. Usually curvature and the aspect ratio of the aneurysm were introduced as decisive factors in medical treatmentWe evaluated these factors by using Computation Fluid Dynamics　(CFD) technology.
3	Virtual Simulation of Particle Imaging Velocity in cerebral aneurysm
4	Contents Study A NON-Pulsatile flow simulation under basic models Modeling of ideal cerebral aneurysm; nine basic models were developed with 3 arterial curvatures (CV) and 3 aspect ratios (AR). Steady flow simulation were carried out using these models. Study B Comparative evaluation of NON-pulsatile flow and Pulsatile flow 　Pulsatile flow model was also created and compared to non-pulsatile flow model
5	Non-pulsatile flow simulation under 9 different models Study A
6	Geometry and simulation parameters Aneurysm geometry and parent artery was set as following　conditions. Arterial length: 60 mm Arterial diameter: 6 mm Aneurysm diameter: 12.5 mm. The aspect ratio was set as 1, 1.5 and 2 The arterial curvatures was set as 0, 90, 180.
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11	Result Non-pulsatile flow simulation under basic models
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14	Non-pulsatile flow simulation
15	Curvature and inflow per square
16	Flow resident time in the aneurysms vs. curvatures
17	Conclusion of Non pulsatile models simulation • The inflow increased by curvature increasing. • The inflow increased by aspect ratio decreasing The highest inflow was found at the case of aspect ratio 1 and curvature 180. For a basic models, a numeric analysis of flow was evaluated.
18	non-pulsatile flow vs pulsatile flow Study B
19	method Pulsatile flow simulations were carried out. Highest inflow　velocisty in steady flow was used. （aspect rate 1.0 , curvature 180) The blood flow conditions which were used the pulsatile flow simulation were measured from a healthy person using Carotid Ultrasound evaluation. The pulsatile results at systole and diastole conditions were used to compare with the result from pulsatile simulation A movement which was created by pulsation at the aneurysm neck was estimated using the results of pulstile simulations.
20	Pulsatile flow
21	Result of pulsatile flow vs non-pulsatile flow
22	Non-Pulsatile flow vs. Pulsatile flow Inflow per square
23	Dynamic Pressure on aneurysmal wall
24	Conclusion of Non-pulsatile flow vs Pulsatile flow Inlet flow per aneurysmal neck square in condition of non-pulsatile and pulsatile is different values. The flow rate of systole was about 2.28 times the value of diastole. The dynamic pressure had about three times the difference between pulsatile flow and non-pulsatile flow. The dynamic pressure may be used to be as one of indicator in prediction of aneurysm growth and ruptured
25	Conclusion Non-pulsatile flow simulation were carried out using the nine basic models that were developed using various artery curvatures (CV) and aspect ratios (AR). The inflow increased by curvature increasing and by aspect ratio decreasing. Pulsatile flow simulation were performed under several typical models, and used to be compared with the results of non-pulsatile flow model. is thought that aneurysm growth and rupture may be predictable by using the dynamic pressure.. In the future, a serial of in-vitro and in-vivo validations will be carried to confirm above simulation results. Furthermore, several hundred clinical cases which were experienced in the Jikei University School of Medicine will be analysed step-by-step.
26	clinical model simulation As example, one clinical model was simulated The clinical case is planed to be evaluated by using this technology in the future.
27	From the clinical images to the analytical images
28	Flow until analyzing by computer simulation
29	Clinical case simulation velocity
30	Clinical case simulation velocity near aneurysmal neck
31	Clinical case simulation velocity and pressure
32	Future 1. In-vitro and in-vivo validation will be carried to confirm the CFD results. 2. Flow patterns and flow mechanisms will be analysed using CFD and other technologies. A serial of methods to control blood flow through into the aneurysm will be proposed. These methods will provide to medical doctors an important standard to diagnosis and treatment the aneurysmal rupture and growing