Publications by authors named "Akio Tomiyama"
Article Synopsis
- - Treatment of vertebrobasilar junction (VBJ) aneurysms is complex, with flow diverters (FDs) being a potential option, but the geometry of these aneurysms poses challenges for intervention.
- - A case study of a 75-year-old male showed that occluding the left vertebral artery (VA) before FD placement led to better flow dynamics and a successful outcome, with the aneurysm disappearing after 18 months.
- - The study highlights the effectiveness of using preoperative computational fluid dynamics (CFD) analysis to guide hybrid surgical strategies for treating VBJ complex aneurysms.
Article Synopsis
- * A study involving a 71-year-old woman showed that using computational fluid dynamic analysis helped in understanding the properties of the aneurysm walls, allowing the surgeons to predict the difficulty of clipping each aneurysm before the operation.
- * After performing the surgery through a pterional craniotomy, the surgeons successfully clipped both aneurysms; the procedure went smoothly, and the patient was discharged without any neurological issues.
Background: The thin-walled regions (TIWRs) of intracranial aneurysms have a high risk of rupture during surgical manipulation. They have been reported to be predicted by wall shear stress and pressure (PS) based on computational fluid dynamics analysis, although this remains controversial. In this study, we investigated whether the oscillatory shear index (OSI) can predict TIWRs.
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- Researchers created a new computational fluid dynamics (CFD) tool to analyze factors related to cerebral aneurysm growth using time-of-flight magnetic resonance angiography (TOF-MRA) data.
- The study compared 6 growing aneurysms with 6 stable aneurysms, focusing on hemodynamic indices like wall shear stress (WSS).
- Results indicated that a temporary increase in WSS during the peak systolic phase may signal a higher risk for future aneurysm enlargement.
Article Synopsis
- The study explores wall shear stress vector cycle variation (WSSVV) as a predictor of thin-walled regions (TIWRs) in cerebral aneurysms, which are prone to rupture during surgery.
- Twelve unruptured cerebral aneurysms were examined, comparing images of TIWRs with those of thick-walled regions (TKWRs) using adjusted WSSVV color maps, leading to the calculation of an optimal maximum color bar value (MCBV) of 500 for effective prediction.
- Results show that low WSSVV values correlate with TIWRs, demonstrating a high sensitivity (89%) and specificity (94%) for identifying these risky areas within the aneurysms.
Implicit-correction-based immersed boundary-lattice Boltzmann method with two relaxation times.
Phys Rev E Stat Nonlin Soft Matter Phys
February 2014
In the present paper, we verify the effectiveness of the two-relaxation-time (TRT) collision operator in reducing boundary slip computed by the immersed boundary-lattice Boltzmann method (IB-LBM). In the linear collision operator of the TRT, we decompose the distribution function into symmetric and antisymmetric components and define the relaxation parameters for each part. The Chapman-Enskog expansion indicates that one relaxation time for the symmetric component is related to the kinematic viscosity.
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