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Computation fluid dynamics (CFD)is widely used to simulate blood flow in vascular systems. Most of the studies focus on identification of reasons behind the cardiovascular disorders. In this study, magnetic resonance angiography data belonging to a patient were used to obtain brain vasculature solid model. This model prior to CFD simulations was evaluated in terms of surface quality and critical region was identified to be investigated. After CFD analysis, the regions with low and high velocity vector fields, pressure, contours and wall shear stresses (WSS) were obtained. The effect of shape and orientation of vessels was observed. It was seen that increased blood velocity increases the pressure and WSS especially in narrow regions. © 2014 IEEE. 2014 18th National Biomedical Engineering Meeting, BIYOMUT 2014 -- 16 October 2014 through 17 October 2014 -- -- 110485

Background: Giant aneurysms at carotid arteries are typically treated with flow diverter (FD) stents in the clinic. Although the goal of an FD stent is to direct most of the blood flow into the main artery, not much is known regarding the effects of wire number an FD possesses on the hemodynamics inside the aneurysm. Methods: In this study, 48-, 72-, and 96-wire FD stents were separately implanted into the site of aneurysm of a 45-year-old woman to evaluate the effects of the FD's number of wires on fluid flow behavior in the aneurysm sac. Time evolution of both finite-time Lyapunov exponent (FTLE) and hyperbolic time fields in the aneurysm sac were calculated by using computational fluid dynamics along with Lagrangian coherent structure (LCS) methods. Results: The computations reveal that a 48-wire FD stent allows a large amount of blood to enter inside the aneurysm sac revealing scattered nonstagnant flow zones formation. Besides, time-dependent results of LCS analysis show that most of the blood flow is diverted into the main artery when 72- and 96-wire number Surpass brand FD stents are separately implanted into the site of the aneurysm, yielding a small amount of blood flow to penetrate into the aneurysm sac. Conclusions: Furthermore, FTLE and hyperbolic time field plots are in good agreement with the patient's digital subtraction angiography image captured 3.5 minutes after 72-wire Surpass brand FD stent implantation. © 2019 Elsevier Inc. 117M491 Türkiye Bilimsel ve Teknolojik Araştirma Kurumu Conflict of interest statement: This work was supported by The Scientific and Technological Research Council of Turkey (TUBITAK) under the 1001 Program (Project no. 117M491).

Blood flow behavior inside an aneurysm is a complex three-dimensional fluid mechanics problem and clarity on this subject can improve or enhance the effectiveness of the treatment. In this study, the fluid flow properties such as velocity, viscosity, wall shear, and pressure are examined by using a computational fluid dynamics (CFD) technique. The patient's angiographic images are provided by the Radiology Department of Uludag University Medical School. These images are converted into a three-dimensional solid model; then, this model is used as a fluid domain in CFD. The blood flow is defined as non-Newtonian, laminar and parabolic pulsatile with two different maximum velocities so that the difference in velocity can be evaluated. The findings are presented in charts for each fluid flow parameter (e.g., velocity, viscosity, wall shear, pressure). © 2019 IEEE. 2019 Medical Technologies Congress, TIPTEKNO 2019 -- 3 October 2019 through 5 October 2019 -- -- 154293 117M491 ACKNOWLEDGMENT This work has been supported by TUBITAK (The Scientific and Technological Research Council of Turkey) under 1001 Program, Project #: 117M491.

Background: Flow diverter stents are often used in the treatment of giant aneurysms at carotid arteries. Although these stents promise to decrease blood flow into the aneurysm sac, little is known about hemodynamics inside the aneurysm once the stent is planted into the aneurysm neck. To further explore this, computational fluid dynamics and Lagrangian coherent structure (LCS) techniques were used to evaluate the time evolution mechanism of stagnation regions inside an aneurysm. The purpose of this work is to provide a quantitative effectiveness comparison of 2 different flow diverter stents placed into the aneurysm neck based on their stagnation zone formations in the sac. Methods: In numerical modeling, Womersley function, and fluidsolid interaction were defined as the 3 cardiac cycles for blood velocity and the aneurysm wall, respectively. Moreover, blood was accepted as a non-Newtonian fluid, and mean arterial blood pressure of the patient was entered into the computational domain to accurately mimic the hemodynamics inside the aneurysm sac accurately. Results: The numerical analyses revealed that the use of a Fred-type stent in the aneurysm neck causes fluid flow zone formations yielding to sequenced stagnated regions. Time evolution of stagnation regions in an aneurysm sac was shown just after a flow diverter stent was employed at a patient's aneurysm neck. Furthermore, the stagnation field in the Fred stent–fitted aneurysm was nearly 4.8 times the stagnation area of the Surpass brand stent–attached aneurysm. Conclusions: Finite time Lyapunov exponent fields obtained from the LCS techniques demonstrated a good agreement with the patient's digital subtraction angiography images obtained just after treatment. © 2019 Elsevier Inc.

The effectiveness of clinical treatments in-stent modeling have been recently started to be analyzed using Computational Fluid Dynamics (CFD) technique. Particularly, variation of pressure loss with flow velocity is used to evaluate permeability and internal resistance coefficients of the flow diverter stents to describe the stent properties to CFD model. The velocity profile is described as pulsatile parabolic at the inlet, the pressure is described at the outlet to be 93 mmHg as a mean arterial pressure (MAP) in the present study. The results implied that there was no significant difference found between porous media and stent implantation of a flow diverter stent modelings based on the studied cases. However, fluid flow simulations indicated that use of 48 wires stent allows more blood flow passing into the aneurysm sac compared to the 72 and 96 wires stents for the studied geometry. Effect of pressure change in the vessel and shape factor of the artery was neglected. © 2019 IEEE. 2019 Medical Technologies Congress, TIPTEKNO 2019 -- 3 October 2019 through 5 October 2019 -- -- 154293 117M491 This work has been supported by TUBITAK (The Scientific and Technological Research Council of Turkey) under 1001 Program, Project #: 117M491.

This study aims classification of phosphorus magnetic resonance spectroscopic imaging (31P-MRSI) data of human brain tumors using machine-learning algorithms. The metabolite peak intensities and ratios were estimated for brain tumor and healthy 31P MR spectra acquired at 3T. The spectra were classified based on metabolite characteristics using logistic regression and support vector machine. This study showed that machine learning could be successfully applied for classification of 31P-MR spectra of brain tumors. Future studies will measure the performance of classification algorithms for 31P-MRSI of brain tumors in a larger patient cohort. © 2014 IEEE. 2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2014 -- 26 August 2014 through 30 August 2014 -- -- 109045

Aneurysms that bulge on intracranial carotid arteries can be detected by using medical imaging technologies. Aneurysm, which is detected in this scope of study, is isolated from the rest of the arteries and vessel cloud with the help of Computer Aided Design (CAD) programme. Obtained geometry is transferred into Computational Fluid Dynamics (CFD) with applicable extension. Drop in pressure, velocity values (x, y, z plane) and wall shear stress (WWS) is recorded through the aneurysm and arteries which aneurysm initialize on. At the same time, this study gave us an opportunity to analyze parameters that affect aneurysm and its' around via visual way. We observed homogenous WWS distribution and consistent velocity values in our simulation outputs. In addition, change in pressure through the aneurysm was recorded. As a result, patient-specific investigation of hemodynamics parameters in-vivo is a quite challenging problem so that image-based CFD is powerful and convenient tool to acquire mentioned parameters for the diagnosis and treatment procedure. © 2015 IEEE. 19th National Biomedical Engineering Meeting, BIYOMUT 2015 -- 5 November 2015 through 6 November 2015 -- -- 118881