Evaluation of Cerebral Aneurysm Stent Performance in a Subject-Specific Computational Model

2010 ◽  
Author(s):  
Timothy J. Gundert ◽  
John F. LaDisa
Keyword(s):  
United States ◽  
Blood Flow ◽  
Computational Model ◽  
Cerebral Aneurysm ◽  
Cerebral Aneurysms ◽  
The United States ◽  
Flow Stagnation ◽  
Subject Specific ◽  
Endovascular Devices ◽  
Saccular Aneurysms

Rupture of cerebral aneurysms is the second leading cause of stroke in the United States [1]. Altered hemodynamics is thought to play a role in the progression and subsequent rupture of aneurysms. Blood flow into an aneurysm can be occluded by surgically clipping the aneurysm or using endovascular devices, such as stents or coils. In saccular aneurysms, coiling alone may be a sufficient method of inducing flow stagnation in the aneurysm, causing thrombosis and preventing rupture. When treating wide-necked aneurysms, stenting is often used in conjunction with coiling to prevent the migration of coils. Many investigators have studied the ability of a stent-only treatment to favorably alter flow in aneurysms [2, 3].

Paradoxical Trends in the Management of Unruptured Cerebral Aneurysms in the United States

Stroke ◽  
2011 ◽  
Vol 42 (6) ◽  
pp. 1730-1735 ◽  
Author(s):  
Michael C. Huang ◽  
Ali A. Baaj ◽  
Katheryne Downes ◽  
A. Samy Youssef ◽  
Eric Sauvageau ◽  
...  
Keyword(s):  
United States ◽  
Cerebral Aneurysms ◽  
The United States ◽  
Unruptured Cerebral Aneurysms

scholarly journals Computed Tomography Image under Optimized Iterative Reconstruction Algorithm to Analyze the Characteristics of Blood Flow Field in Cerebral Aneurysm before and after Stent Implantation

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Kunyang Bao ◽  
Chao Liu ◽  
Jin Li ◽  
Xiang Liu ◽  
Wenzhang Luo ◽  
...  
Keyword(s):  
Blood Flow ◽  
Flow Field ◽  
Cerebral Aneurysm ◽  
Iterative Reconstruction ◽  
Stent Implantation ◽  
Cerebral Aneurysms ◽  
Reconstruction Algorithm ◽  
Ct Images ◽  
Iterative Reconstruction Algorithm ◽  
The Difference

In order to analyze the change characteristics of blood flow field in cerebral aneurysms before and after stent implantation, this study first constructed an optimized iterative reconstruction algorithm to reconstruct CT images of patients with cerebral aneurysms and used it to solve the problem of image sharpness. In addition, backprojection image reconstruction algorithm and Fourier transform analytic method were introduced. According to the CT images of cerebral arteries of patients, the lesions were presented in a three-dimensional and visual way through the reconstructed three-dimensional images, thus achieving the effects of simulation and simulation. The results showed that the sensitivity, specificity, and accuracy of the optimized iterative reconstruction algorithm were 90.78%, 83.27%, and 94.82%, which were significantly higher than those of the backprojection image reconstruction algorithm and Fourier transform analysis method, and the difference was statistically significant ( P < 0.05 ). Before operation, the blood flow velocity in the neck of aneurysm was 7.35 × 10−2 m/s, the exit velocity was 1.51 × 10−1 m/s, and the maximum velocity appeared in the upstream part of the exit. After passing through the aneurysm, the blood flow velocity began to decrease gradually, forming a vortex at the top of the tumor. After stent implantation, the neck and outlet velocities of cerebral aneurysm were 9.352 × 10−2 m/s and 1.897 × 10−2 m/s, respectively. The velocity of blood flow decreased after entering the aneurysm, and there was no vortex at the top of the aneurysm. Among the outlet velocities of arterial blood vessels, the velocity before stent implantation was significantly lower than that after stent implantation, and the difference was statistically significant ( P < 0.05 ). Compared with prestent, the shear force distribution on the wall of cerebral aneurysm showed a significant decrease, and the difference was statistically significant ( P < 0.05 ). To sum up, pelvic floor ultrasound based on hybrid iterative reconstruction algorithm has high accuracy in diagnosing the changes of blood flow field in cerebral aneurysms. The application of CT images in the diagnosis of cerebral aneurysms can objectively provide imaging data for clinical practice and has high application value.

scholarly journals In vivo cerebral aneurysm models

2019 ◽  
Vol 47 (1) ◽  
pp. E20 ◽  
Author(s):  
John W. Thompson ◽  
Omar Elwardany ◽  
David J. McCarthy ◽  
Dallas L. Sheinberg ◽  
Carlos M. Alvarez ◽  
...  
Keyword(s):  
Cerebral Aneurysm ◽  
Surgical Techniques ◽  
Cerebral Aneurysms ◽  
Aneurysm Rupture ◽  
Large Animal ◽  
Pharmacological Interventions ◽  
Large Animal Models ◽  
First Line Therapy ◽  
Endovascular Devices

Cerebral aneurysm rupture is a devastating event resulting in subarachnoid hemorrhage and is associated with significant morbidity and death. Up to 50% of individuals do not survive aneurysm rupture, with the majority of survivors suffering some degree of neurological deficit. Therefore, prior to aneurysm rupture, a large number of diagnosed patients are treated either microsurgically via clipping or endovascularly to prevent aneurysm filling. With the advancement of endovascular surgical techniques and devices, endovascular treatment of cerebral aneurysms is becoming the first-line therapy at many hospitals. Despite this fact, a large number of endovascularly treated patients will have aneurysm recanalization and progression and will require retreatment. The lack of approved pharmacological interventions for cerebral aneurysms and the need for retreatment have led to a growing interest in understanding the molecular, cellular, and physiological determinants of cerebral aneurysm pathogenesis, maturation, and rupture. To this end, the use of animal cerebral aneurysm models has contributed significantly to our current understanding of cerebral aneurysm biology and to the development of and training in endovascular devices. This review summarizes the small and large animal models of cerebral aneurysm that are being used to explore the pathophysiology of cerebral aneurysms, as well as the development of novel endovascular devices for aneurysm treatment.

Surface Stiffness of Patient-Specific Arterial Segments With Varying Plaque Compositions

2013 ◽  
Author(s):  
Craig J. Bennetts ◽  
Ahmet Erdemir ◽  
Melissa Young
Keyword(s):  
United States ◽  
Blood Flow ◽  
Peripheral Arterial Disease ◽  
Arterial Disease ◽  
The United States ◽  
Patient Specific ◽  
Large Arteries ◽  
Surface Stiffness ◽  
Peripheral Arterial

Peripheral arterial disease (PAD), resulting from the accumulation of plaque, causes obstruction of blood flow in the large arteries in the arm and leg. In the United States, approximately 8.4 million people over the age of 40 have PAD [1]. If not treated, PAD can cause ischemic ulcerations and gangrene, which could eventually lead to amputation. Approximately, 25% of patients with PAD have worsening limb symptoms over 5 years, 7% requiring revascularization, and 4% requiring amputation [2].

Development of Stent Strut Pattern for Cerebral Aneurysm

2010 ◽  
Author(s):  
Toshio Nakayama ◽  
Shinkyu Jeong ◽  
Srinivas Karkenahalli ◽  
Makoto Ohta
Keyword(s):  
Blood Flow ◽  
Cerebral Aneurysm ◽  
Cerebral Aneurysms ◽  
Optimization Method ◽  
Flow Speed ◽  
Parent Artery ◽  
Stent Strut ◽  
Computational Fluid Dynamics Cfd ◽  
Commercial Solver ◽  
Volume Method

Background and purpose: Stent implantation (stenting) in intracranial arteries is termed as endovascular treatment. The number of such cases has been increasing worldwide because the surgical damage resulting from stenting seem to be less than that of other treatments. The role of stenting for cerebral aneurysms is to reduce the blood flow speed in cerebral aneurysms. We have developed a computational fluid dynamics (CFD) system using a realistic stent and blood vessel and have studied the effect of the stent. Results of our study showed the stent strut pattern and stenting position to be very effective for reducing the blood flow speed in cerebral aneurysms. We have in describe the designing method used to design the stent strut pattern which reduces both the blood flow speed and the wall shear stress (WSS). Methods: An idealized aneurysm, a parent artery, and various stent shapes were used. The shape of the parent artery was a straight pipe and the aneurysm was a sphere. The stent was implanted in the neck of the aneurysm. The porosity remained of 80%, and the width of the stent strut ranged from 90 to 160[μm]. The stent strut height was fixed at a constant 150 [μm]. For the constructed shape data, a tetrahedron numerical mesh was generated. Calculation using the finite volume method was performed by a commercial solver. The optimization method was applied to the CFD results, and the stent strut patterns that reduced the blood flow speed and the WSS most were determined. Conclusion: The development method of stent strut pattern was proposed. Various stent strut patterns to reduce blood flow speed and WSS in/on cerebral aneurysm were tested. The stent strut pattern that reduced the blood flow speed and that reduced the WSS were determined. In the future works, the number of CFD cases should be increased and the optimal stent strut pattern determined.

Simulation of Blood Flow in Deformable Arteries Using Subject-Specific Geometry and Variable Vessel Wall Properties

2009 ◽  
Author(s):  
Guanglei Xiong ◽  
C. Alberto Figueroa ◽  
Nan Xiao ◽  
Charles A. Taylor
Keyword(s):  
Blood Flow ◽  
Geometric Model ◽  
Cerebral Aneurysms ◽  
Patient Specific ◽  
Wall Properties ◽  
Subject Specific ◽  
Vessel Wall Properties ◽  
Specific Geometry ◽  
Variable Wall ◽  
Dynamics Simulations

Previous efforts to simulate blood flow in patient-specific models either assumed rigid vessel walls or deformable walls with constant mechanical property [1]. We have developed a new workflow to enable blood flow and vessel dynamics simulations using subject-specific geometry and variable wall properties. The geometric model construction is based on 3D segmentation and geometric processing which greatly reduce human labor and increase the objectivity of the model. Variable wall properties are assigned to the model based on combining centerline-based and surface-based methods. This new approach was successfully applied to simulate blood flow and wall dynamics in models with abdominal, thoracic, and cerebral aneurysms.

Classification of Blood Flow in Cerebral Aneurysm Considering the Parent Artery Curves

2013 ◽  
Author(s):  
Toshio Nakayama ◽  
Shin-ichiro Sugiyama ◽  
Makoto Ohta
Keyword(s):  
Blood Flow ◽  
Flow Pattern ◽  
Cerebral Aneurysm ◽  
Cerebral Aneurysms ◽  
Flow Simulation ◽  
Flow Speed ◽  
Parent Artery ◽  
Blood Flow Pattern ◽  
Stent Strut

Background and purpose: Recently, the number of endovascular treatments has increased worldwide because of advances in minimally invasive surgery. We considered the effect of reduced flow due to stent implantation and proposed the design of stent strut pattern from the viewpoint of fluid dynamics. We developed an optimized stent strut pattern using a computational fluid dynamics (CFD) system. A classification of cerebral aneurysms was proposed using the aspect ratio (AR) and the stent strut pattern was optimized. The results of optimal stent strut pattern for reduced blood flow speed and wall shear stress were different, and the influence of the AR values was small because there was no dependence on relationship between blood flow and the AR values due to the use of a straight pipe in the parent artery. The classification of blood flow pattern in a cerebral aneurysm must consider the parent artery curves. In this study, we investigated the relationship between the blood flow pattern in cerebral aneurysms and parent artery curves using CFD. Methods: To investigate the influence of blood flow based on the parent artery curve, the parent artery shape was constructed as follows. Patient-specific parent artery shape with a cerebral aneurysm was reconstructed using OsiriX. Center line was extracted using a vascular modeling tool kit. The parent artery shape was reconstructed based on this center line using CAD. The diameter of the parent artery was 4 mm. The cerebral aneurysm shape was a combination of a straight pipe and a half sphere, and the AR value was fixed at 1.0. The cerebral aneurysm position varied from the original position to a 180° rotated position. Tetrahedral numerical mesh was generated with a commercial mesh generator (ICEM CFD 14.0; Ansys Inc.) for the CFD analysis. The numerical blood flow simulation was performed on a supercomputer using the commercial ANSYS FLUENT 6.3 software package and the finite volume method, and a steady flow simulation was performed. Boundary conditions were set for velocity at the inlet, pressure at the outlet, no-slip parent artery, and stent surface. Reynolds numbers at the inlet determined from the mean blood flow speed were 240 and 600. Results and discussion: In this study, we revealed the blood flow pattern in some cerebral aneurysms using CFD. The pattern in a cerebral aneurysm was influenced by the aneurysm direction and parent artery curves. The blood flow pattern in a neck cerebral aneurysm was classified into two types.

Abstract 1122‐000063: Postoperative Recanalization Factors of Coil Embolization for Cerebral Aneurysms with Comparable Volume Embolization Ratio

2021 ◽  
Vol 1 (S1) ◽  
Author(s):  
Hayato Uchikawa ◽  
Hiroyuki Takao ◽  
Soichiro Fujimura ◽  
Yuya Uchiyama ◽  
Yuma Yamanaka ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Aneurysm ◽  
High Velocity ◽  
Coil Embolization ◽  
Cerebral Aneurysms ◽  
Mean Value ◽  
Morphological Parameters ◽  
Hemodynamic Parameters ◽  
Concentrated Flow ◽  
Coil Shape

Introduction : Volume embolization ratio (VER) has been reported to be involved in postoperative recanalization of coil embolization. However, despite comparable VER, some cases remained stable, and the others showed recanalization. Hemodynamic and morphological factors, as described in previous studies, may also influence recanalization in addition to VER. In this study, we focused on cerebral aneurysms treated by coil embolization with comparable VER. Blood flow analysis using computational fluid dynamics (CFD) and geometrical measurements were performed to investigate the recanalization factors. Methods : We focused on the aneurysms that underwent coil embolization with 15–20% VER. The criteria for the case selection were that the size of the aneurysms was 5–10 mm and that the aneurysm was treated by only coil (i.e., the stent‐assisted cases were excluded). Aneurysms that recanalized after coil embolization and underwent additional coil deployment were defined as “recanalized”, and aneurysms that remained stable after coil embolization without coil compaction were defined as “stable”. Finally, we selected 7 recanalized cases (ICA: 1, MCA: 3, ACA: 3) and 18 stable cases (ICA: 6, MCA: 3, ACA: 9). CFD analysis and morphometry were performed on the vessel geometry after coil embolization. The coil shape was modeled by the virtual coil technique. We calculated three morphological parameters and 34 hemodynamic parameters, then we compared them between the recanalized and stable cases using the Mann‐Whitney U test to identify recanalization factors. In addition, we reconstructed the coil shape from medical images and compared its structure and flow characters for stable and recanalized cases. Results : The average VER for the cases analyzed in this study were 16.7% for recanalized cases and 17.7% for stable cases. As hemodynamic parameters, the spatially averaged velocity normal to the neck plane into the cerebral aneurysm ( NV neck ), and the ratio of the area where blood flows into the cerebral aneurysm after the coil embolization to the area of the neck surface (inflow area ratio: IAR) showed significant difference. Although the hemodynamic parameters were significantly different, morphological parameters did not show statistically significance. In the recanalized case, NV neck tended to be higher (mean value, recanalized: 0.931, stable: 0.822, P < 0.05), and IAR tended to be lower (mean value, recanalized: 0.319, stable: 0.408, P < 0.01). The high NV neck and low IAR indicate that the aneurysm had concentrated flow with a high velocity at the neck surface. There was the concentrated blood flow with the high velocity that collided with the modeled coil in a CFD result for the recanalized case. The area where the blood flow impinged on the modeled coil coincided with the compacted coil region reconstructed from medical images. Therefore, a large force on the coil indicated by these hemodynamic parameters may cause the postoperative recanalization. Conclusions : Even with the same level of VER, there was a possibility of recanalization in aneurysms with a high velocity and concentrated flow into the aneurysm. It is necessary to consider not only VER but also hemodynamic factors to investigate recanalization factors after the coil embolization.

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