Takashi Suzuki1, Hiroyuki Takao1,2,3, Takamasa Suzuki4, Tomoaki Suzuki2, Shunsuke Masuda2, Chihebeddine Dahmani2,5, Mitsuyoshi Watanabe2, Hiroya Mamori6, Toshihiro Ishibashi2, Hideki Yamamoto4, Makoto Yamamoto6, Yuichi Murayama2. 1. Graduate School of Mechanical Engineering, Tokyo University of Science, Tokyo, Japan. 2. Division of Endovascular Neurosurgery, Department of Neurosurgery, The Jikei University School of Medicine, Tokyo, Japan. 3. Department of Innovation for Medical Information Technology, The Jikei University School of Medicine, Tokyo, Japan. 4. Department of Chemical, Energy and Environment Engineering, Kansai University, Osaka, Japan. 5. Siemens Japan K.K., Shinagawa-ku, Tokyo, Japan. 6. Department of Mechanical Engineering, Tokyo University of Science, Tokyo, Japan.
Abstract
BACKGROUND: In most simulations of intracranial aneurysm hemodynamics, blood is assumed to be a Newtonian fluid. However, it is a non-Newtonian fluid, and its viscosity profile differs among individuals. Therefore, the common viscosity assumption may not be valid for all patients. OBJECTIVE: This study aims to test the suitability of the common viscosity assumption. METHODS: Blood viscosity datasets were obtained from two healthy volunteers. Three simulations were performed for three different-sized aneurysms, two using measured value-based non-Newtonian models and one using a Newtonian model. The parameters proposed to predict an aneurysmal rupture obtained using the non-Newtonian models were compared with those obtained using the Newtonian model. RESULTS: The largest difference (25%) in the normalized wall shear stress (NWSS) was observed in the smallest aneurysm. Comparing the difference ratio to the NWSS with the Newtonian model between the two Non-Newtonian models, the difference of the ratio was 17.3%. CONCLUSIONS: Irrespective of the aneurysmal size, computational fluid dynamics simulations with either the common Newtonian or non-Newtonian viscosity assumption could lead to values different from those of the patient-specific viscosity model for hemodynamic parameters such as NWSS.
BACKGROUND: In most simulations of intracranial aneurysm hemodynamics, blood is assumed to be a Newtonian fluid. However, it is a non-Newtonian fluid, and its viscosity profile differs among individuals. Therefore, the common viscosity assumption may not be valid for all patients. OBJECTIVE: This study aims to test the suitability of the common viscosity assumption. METHODS: Blood viscosity datasets were obtained from two healthy volunteers. Three simulations were performed for three different-sized aneurysms, two using measured value-based non-Newtonian models and one using a Newtonian model. The parameters proposed to predict an aneurysmal rupture obtained using the non-Newtonian models were compared with those obtained using the Newtonian model. RESULTS: The largest difference (25%) in the normalized wall shear stress (NWSS) was observed in the smallest aneurysm. Comparing the difference ratio to the NWSS with the Newtonian model between the two Non-Newtonian models, the difference of the ratio was 17.3%. CONCLUSIONS: Irrespective of the aneurysmal size, computational fluid dynamics simulations with either the common Newtonian or non-Newtonian viscosity assumption could lead to values different from those of the patient-specific viscosity model for hemodynamic parameters such as NWSS.
Authors: Rafał Morga; Marek Moskała; Tadeusz Popiela; Marek Rajzer; Aleksander Wilk; Michał Kłosiński; Tomasz Muszyński; Mariusz Trystuła Journal: Med Sci Monit Date: 2020-03-31