Publications (3)4.45 Total impact
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Article: Computational fluid dynamics of carotid arteries after carotid endarterectomy or carotid artery stenting based on postoperative patient-specific computed tomography angiography and ultrasound flow data.
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ABSTRACT: There are significant differences in the postoperative morphological and hemodynamic conditions of the carotid arteries between carotid artery stenting (CAS) and endarterectomy (CEA). To compare the postoperative rheological conditions after CAS with those after CEA with patch angioplasty (patch CEA) through the use of computational fluid dynamics (CFD) based on patient-specific data. The rheological conditions in the carotid arteries were simulated in 2 patients after CAS and in 2 patients after patch CEA by CFD calculations. Three-dimensional reconstruction of the carotid arteries was performed with the images obtained with computed tomography angiography. The streamlines and wall shear stress (WSS) were calculated by a supercomputer. Adequate boundary conditions were determined by comparing the simulation results with ultrasound flow data. CFD was successfully calculated for all patients. The differences between the flow velocities of ultrasound data and those of the simulation results were limited. In the streamline analysis, the maximum flow velocities in the internal carotid artery after patch CEA were around two-thirds of those after CAS. Rotational slow flow was observed in the internal carotid artery bulb after patch CEA. WSS analysis found regional low WSS near the outer wall of the bulb. High WSS was observed at the distal end of the arteriotomy after patch CEA and at the residual stenosis after CAS. CFD of postoperative carotid arteries disclosed the differences in streamlines and WSS between CAS and patch CEA. CFD may allow us to obtain adequate rheological conditions conducive to achieving the best clinical results.Neurosurgery 01/2011; 68(4):1096-101; discussion 1101. · 2.79 Impact Factor -
Chapter: 3D Observation of Expansion of Stent and Elastic Recoil using Micro-CT
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ABSTRACT: The behavior of an expansion of balloon-expandable stent is in three-dimensional space. Therefore, it is necessary to observe in three-dimensions, however little previous research measures this behavior in three-dimensional space. Micro-CT is an image device that can observe more accurately with three-dimensions than the conventional CT. We reconstructed the stent shape using the medical image obtained by Micro-CT in three-dimensions. We observed the behavior of stent and the elastic recoil of stent (ERS), and measured ERS quantitatively. This aim is to observe the three-dimensional expansion behavior and ERS using Micro-CT, and evaluate quantitatively. We observed the three-dimensional expansion behavior of stent. Despite, the similarity of structures, the expansion behavior of stent and ERS were different in each structure. Moreover, we evaluated ERS quantitatively in proximal and distal of each structure influence from the balloon pressure. ERS ratio ranged from 4.7 % to 6.7 % in proximal and distal. When dividing stent into two in the direction of the length axis, ERS is shown proximal < distal in structures 1st to 3rd, and ERS is shown proximal > distal in structures 4th to 6th. And it reduces in the direction of a minor axis by maximum ERS 5.7%. We observed three-dimensional behavior of balloon-expandable stent and the ERS, and evaluate ERS quantitatively using Micro-CT. We found that it is necessary to observe in three-dimensions. KeywordsThree-dimensional-Micro-CT-Elastic Recoil of Stent-Expansion Behavior-Balloon-Expandable Stent01/2010: pages 235-238; -
Article: Vertebrobasilar junction fenestration with dumbbell-shaped aneurysms formation: computational fluid dynamics analysis.
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ABSTRACT: We report 8 rare cases of paired ANs involving fenestrated vertebrobasilar junction and demonstrate the flow patterns of the paired ANs by qualitative CFD analysis in 5 cases. Two-dimensional and 3-dimensional angiographic features of 8 cases were reviewed. Nine patient-specific geometries of CFD models in 5 cases were created for flow analysis. All 8 cases had 2 ANs, one large and the other small, projecting to the opposite sides at the proximal end of fenestrated vertebrobasilar junction. The different angiographic findings between right VA and left VA suggested the different hemodynamic characteristics of the respective VAs. Computational fluid dynamics analysis also demonstrated that the inflows of these paired ANs were different between right VA and left VA. Flow simulations by CFD were consistent with angiographic findings. Intrinsic wall defects at fenestrated vertebrobasilar junction and specific hemodynamic stresses from 2 inflows may contribute to the formation of a pair of dumbbell-shaped ANs.Surgical Neurology 09/2009; 72 Suppl 2:S11-9. · 1.67 Impact Factor
