scholarly journals Virtual Reality Visualization of CFD Simulated Blood Flow in Cerebral Aneurysms Treated with Flow Diverter Stents

2021 ◽  
Vol 11 (17) ◽  
pp. 8082
Author(s):  
Sima Baheri Islami ◽  
Mike Wesolowski ◽  
William Revell ◽  
Xiongbiao Chen
Keyword(s):  
Blood Flow ◽  
Virtual Reality ◽  
Flow Behavior ◽  
Cerebral Aneurysms ◽  
Point Clouds ◽  
Parent Artery ◽  
Time Varying ◽  
Head Mounted Display ◽  
Aneurysm Treatment ◽  
The Impact

Virtual reality (VR) has the potential to be a powerful tool for the visualization of simulated blood flow in cerebral aneurysms. This paper presents our study aimed at developing the VR visualization of computational fluid dynamics (CFD) simulations of cerebral aneurysms treated with flow-diverting (FD) stents. First, a spherical sidewall aneurysm located at a simplified internal carotid artery was considered for investigating the impact of stent deployment and positioning on the corresponding spatially time-varying blood flow behavior. The three-dimensional unsteady blood flow over a cardiac cycle was simulated numerically using the finite volume method, and the distributions of hemodynamic parameters inside the aneurysm sac, and on its wall, were presented with and without stent cases. Two stent positions, with and without a gap between the artery wall and stent, were considered to show the influence of correct stent position on aneurysm treatment. Second, a straightforward workflow was developed to import, process, and visualize the CFD analysis data in a VR environment by using open-source software with a high resolution. The Unity3D engine was used for displaying the processed animations in a VR environment operated on a head-mounted display (HMD). The refining process of each frame of time-varying CFD data was automated. The animated flow elements rendered in the VR environment were velocity vectors, velocity contours, streamlines, particle traces, and point clouds. CFD results showed that proper stenting facilitates thrombosis and occlusion of the aneurysm by modification of the flow patterns, which leads to lower inflow jet velocities into the aneurysm, longer turnover time, lower aneurysm-averaged kinetic energy, and lower wall shear stress. Additionally, the results indicated that a gap between the stent and the parent artery may lead to undesirable hemodynamic alterations. The VR visualization illustrated that the recognition of the potential in danger regions of aneurysms and the evaluation of the performance of FD stents in aneurysm treatment can be conducted without the need for several slices through the parent artery and aneurysm, as is required for traditional postprocessing methods. Through VR visualization, the details of the simulation results become readily available by navigating in the 3D animated flow elements using a high-degree-of-freedom headset.

scholarly journals Gamification and Hazard Communication in Virtual Reality: A Qualitative Study

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4663
Author(s):  
Janaina Cavalcanti ◽  
Victor Valls ◽  
Manuel Contero ◽  
David Fonseca
Keyword(s):  
Virtual Reality ◽  
New Technologies ◽  
Training Environment ◽  
Hazard Communication ◽  
Head Mounted Display ◽  
Compliance Behavior ◽  
Before And After ◽  
Recorded Data ◽  
The Impact ◽  
Different Levels

An effective warning attracts attention, elicits knowledge, and enables compliance behavior. Game mechanics, which are directly linked to human desires, stand out as training, evaluation, and improvement tools. Immersive virtual reality (VR) facilitates training without risk to participants, evaluates the impact of an incorrect action/decision, and creates a smart training environment. The present study analyzes the user experience in a gamified virtual environment of risks using the HTC Vive head-mounted display. The game was developed in the Unreal game engine and consisted of a walk-through maze composed of evident dangers and different signaling variables while user action data were recorded. To demonstrate which aspects provide better interaction, experience, perception and memory, three different warning configurations (dynamic, static and smart) and two different levels of danger (low and high) were presented. To properly assess the impact of the experience, we conducted a survey about personality and knowledge before and after using the game. We proceeded with the qualitative approach by using questions in a bipolar laddering assessment that was compared with the recorded data during the game. The findings indicate that when users are engaged in VR, they tend to test the consequences of their actions rather than maintaining safety. The results also reveal that textual signal variables are not accessed when users are faced with the stress factor of time. Progress is needed in implementing new technologies for warnings and advance notifications to improve the evaluation of human behavior in virtual environments of high-risk surroundings.

Cinematic Angiography for Measurements of Blood Flow in Cerebral Aneurysms With Stents

2007 ◽  
Author(s):  
Makoto Ohta ◽  
Naoko Fujimura ◽  
Luca Augsburger ◽  
Hasan Yilmaz ◽  
Daniel A. Ru¨fenacht
Keyword(s):  
Blood Flow ◽  
High Speed ◽  
Cerebral Aneurysms ◽  
Flow Speed ◽  
Circulation System ◽  
Parent Artery ◽  
Vortex Center ◽  
System A ◽  
Before And After ◽  
Movement Distance

Background and Purpose: The assessment of blood flow speed by imaging modalities is important for endovascular treatments, such as stent implantation, of cerebral aneurysms. The subtracted vortex centers path line method (SVC method) is one of the ways of determining flow speed quantitatively using the image sequence. And a cinematic angiography (CA) is a high speed image acquisition system using X-ray and contrast media integrated in Digital Subtraction Angiography (DSA) for endovascular therapy. The combination of SVC and CA may useful for determining the blood flow speed during the operation using DSA. In this study, we applied this combination to analyze hemodynamic changes before and after stenting. Methods: A transparent tubular model was constructed of silicone which included an aneurysm 10 mm in diameter and having a 5 mm neck on a straight parent artery with a diameter of 3.5 mm. The model was integrated into a pulsatile circulation system. A double layer stent was placed in the parent artery on the aneurysm. By CA, successive images at 25 frames per second with injection of contrast were obtained. Results and conclusion: Rotating vortexes of contrast, which advanced along the wall of the aneurysm, were observed in successive images of the aneurysm cavity. The movement distance of the vortex center was measured and the results show that the vortex speed decrease after stenting. This indicates the possibility of applying the SVC method to medical imaging equipment for analysis of the flow in aneurysms containing stent.

scholarly journals Discrepancy between two-dimensional and three-dimensional digital subtraction angiography for the planning of endovascular coiling of small cerebral aneurysms <5 mm

2020 ◽  
Vol 26 (6) ◽  
pp. 733-740
Author(s):  
Te-Chang Wu ◽  
Yu-Kun Tsui ◽  
Tai-Yuan Chen ◽  
Ching-Chung Ko ◽  
Chien-Jen Lin ◽  
...  
Keyword(s):  
Digital Subtraction Angiography ◽  
Three Dimensional ◽  
Cerebral Aneurysms ◽  
Endovascular Coiling ◽  
Parent Artery ◽  
Two Dimensional ◽  
Digital Subtraction ◽  
Rotational Angiography ◽  
Treatment Choices ◽  
The Impact

Background To investigate the discrepancy between two-dimensional digital subtraction angiography and three-dimensional rotational angiography for small (<5 mm) cerebral aneurysms and the impact on decision making among neuro-interventional experts as evaluated by online questionnaire. Materials and methods Eight small (<5 mm) ruptured aneurysms were visually identified in 16 image sets in either two-dimensional or three-dimensional format for placement in a questionnaire for 11 invited neuro-interventionalists. For each set, two questions were posed: Question 1: “Which of the following is the preferred treatment choice: simple coiling, balloon remodeling or stent assisted coiling?”; Question 2: “Is it achievable to secure the aneurysm with pure simple coiling?” The discrepancies of angio-architecture parameters and treatment choices between two-dimensional-digital subtraction angiography and three-dimensional rotational angiography were evaluated. Results In all eight cases, the neck images via three-dimensional rotational angiography were larger than two-dimensional-digital subtraction angiography with a mean difference of 0.95 mm. All eight cases analyzed with three-dimensional rotational angiography, but only one case with two-dimensional-digital subtraction angiography were classified as wide-neck aneurysms with dome-to-neck ratio < 1.5. The treatment choices based on the two-dimensional or three-dimensional information were different in 56 of 88 (63.6%) paired answers. Simple coiling was the preferred choice in 66 (75%) and 26 (29.6%) answers based on two-dimensional and three-dimensional information, respectively. Three types of angio-architecture with a narrow gap between the aneurysm sidewall and parent artery were proposed as an explanation for neck overestimation with three-dimensional rotational angiography. Conclusions Aneurysm neck overestimation with three-dimensional rotational angiography predisposed neuro-interventionalists to more complex treatment techniques. Additional two-dimensional information is crucial for endovascular treatment planning for small cerebral aneurysms.

scholarly journals Predictive modeling and in vivo assessment of cerebral blood flow in the management of complex cerebral aneurysms

2016 ◽  
Vol 36 (6) ◽  
pp. 998-1003 ◽  
Author(s):  
Brian P Walcott ◽  
Clemens Reinshagen ◽  
Christopher J Stapleton ◽  
Omar Choudhri ◽  
Vitaliy Rayz ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Aneurysms ◽  
Improve Risk Stratification ◽  
Complex Aneurysms ◽  
Aneurysm Treatment ◽  
Circulation Patterns ◽  
Recent Developments ◽  
Surgical Bypass ◽  
In Vivo Assessment

Cerebral aneurysms are weakened blood vessel dilatations that can result in spontaneous, devastating hemorrhage events. Aneurysm treatment aims to reduce hemorrhage events, and strategies for complex aneurysms often require surgical bypass or endovascular stenting for blood flow diversion. Interventions that divert blood flow from their normal circulation patterns have the potential to result in unintentional ischemia. Recent developments in computational modeling and in vivo assessment of hemodynamics for cerebral aneurysm treatment have entered into clinical practice. Herein, we review how these techniques are currently utilized to improve risk stratification and treatment planning.

ANALYSIS OF BLOOD FLOW PASSING THROUGH AORTIC AND MITRAL VALVES USING A COMPUTATIONAL MODEL OF CONCENTRATED PARAMETERS

2014 ◽  
Vol 26 (06) ◽  
pp. 1450068
Author(s):  
J. Del Río Palma ◽  
E. Romero V. ◽  
M. Cerrolaza
Keyword(s):  
Blood Flow ◽  
Heart Valves ◽  
Computational Models ◽  
Flow Behavior ◽  
Flow Analysis ◽  
High Mobility ◽  
Abnormal Behavior ◽  
Factors Affecting ◽  
Main Factors ◽  
The Impact

Blood flow has been extensively studied because of its close relationship with cardiovascular disease. Heart valves blood flow analysis is particularly complex due to the high mobility of its leaflets, a fact that has stimulated the development of computational models aimed to its better understanding. For studying heart valves blood flow, we developed a mathematical model derived from clinical observations based on echocardiographic images, which describe valve leaflets motion and its influence on blood flow. This work presents a concentrated-parameters-based model of heart valves blood flow that takes into consideration five main factors affecting such a flow in the mitral and aortic valves. This model considers factors that are related to blood fluid and valve leaflets characteristics. Considering the main factors involved, it was found that blood flow exhibit an abnormal behavior in response to small variations (less than 10%) in blood pressure gradient or in leaflets stiffness. Likewise, after changing the roughness of the leaflets, the impact is smaller, only slightly affecting blood flow behavior with changes beyond 30%. Moreover, it was observed that the influence of fluid vortices originated behind the valves can be disregarded and the kinetic energy induced by them is almost negligible.

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.

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.

scholarly journals Effect of Immersive Virtual Reality on Pain and Anxiety at a Veterans Affairs Health Care Facility

2021 ◽  
Vol 2 ◽  
Author(s):  
Caitlin R. Rawlins ◽  
Zachary Veigulis ◽  
Catherine Hebert ◽  
Catherine Curtin ◽  
Thomas F. Osborne
Keyword(s):  
Health Care ◽  
Virtual Reality ◽  
Rating Scale ◽  
Medical Center ◽  
Care Facility ◽  
Veterans Affairs ◽  
Primary Objective ◽  
Head Mounted Display ◽  
Anxiety Levels ◽  
The Impact

Objectives: The primary objective of this evaluation is to determine the impact of virtual reality (VR) distraction on acute and chronic pain in Veterans within the Veterans Affairs Health Care System (VA). A secondary objective is to determine the impact of VR on the experience of stress and anxiety in Veterans utilizing VR for the indication of pain. A third objective is to develop an understanding of the Veteran experience of using VR in a healthcare setting.Methods: This prospective, pretest-posttest mixed methods assessment was performed at a VA medical center from August 30, 2019 to November 23, 2020. VR experiences lasted between 10 and 30 min utilizing an immersive head-mounted display with multiple, autonomously chosen virtual environments. Qualitative data was collected concurrently to provide context to quantitative measures which included pain scores and stress/anxiety levels. Data from 79 participants was included in this analysis. Data included pre- and post-VR session Defense and Veterans Pain Rating Scale and stress/anxiety levels.Results: Results for the cohort demonstrated a statistically significant decrease in pain intensity (p &lt;0 .001) with an average 12% decrease in pain levels and an 92% reduction in anxiety for those in concurrent pain.Conclusion: VR as a non-pharmacological adjunct or alternative modality, appears to be a viable option for improving pain management and reducing anxiety in Veteran populations across various age ranges, and levels of acuity and chronicity. VR was found to be an effective distraction from pain, a pleasurable experience for the majority, and opened the door to other non-pharmacological modalities in a Veteran population.

scholarly journals Virtual reality as a tool for environmental conservation and fundraising

2019 ◽  
Author(s):  
Katherine M. Nelson ◽  
Eva Anggraini ◽  
Achim Schlüter
Keyword(s):  
Virtual Reality ◽  
Field Experiments ◽  
New Technologies ◽  
Message Framing ◽  
Marine Conservation ◽  
Environmental Conservation ◽  
Head Mounted Display ◽  
Positive Message ◽  
Negative Message ◽  
The Impact

AbstractAnecdotal evidence from philanthropic fundraisers shows that virtual reality (VR) technology increases empathy and can influence people toward pro-environmental behavior. Non-profit organizations are increasingly marketing their causes using virtual reality and they report increased donations when VR technology is employed. In VR, users are immersed in situations intended to feel more like the real world through technology, such as 360° video screened through 3D headsets that block out visual and auditory distractions. The framing of the message as either positive or negative has long shown to have an effect on behavior, although consensus on the impact of framing has not been reached in relation to encouraging contributions to public goods. This paper focuses on field experiments used to investigate the effects of varying degrees of visual immersion and positive versus negative message framing on respondents’ contributions to a conservation charity. Participants were exposed to a five-minute underwater film about coral reefs and the importance of protecting them. We employed a 2×2 experimental design using 3D head-mounted displays comparing 360° film footage vs. unidirectional film and a positive message vs. a negative message. After watching the film, each participant completed a short questionnaire and had the opportunity to donate to a marine conservation charity. In addition, we tested a control treatment where no video was observed. The video was filmed in Indonesia which is host to some of the world’s most biodiverse reefs that are under great threat from human activity. We also conducted the study in Indonesia, sampling a total of 1006 participants from the Bogor city area and tourists on the island of Gili Trawangan - which is popular for scuba diving and snorkeling. We find significant differences in observed behavior and reported emotions between all treatments compared to the control condition. Among the tourist sample, we find significant differences between the 360° film with a negative message which garnered significantly larger average donation amounts compared to the unidirectional film with both positive and negative framing. Overall, we can infer from these studies that virtual reality is an effective way to raise awareness of environmental threats and encourage behavioral action, especially when tailored to target groups. New technology, such as the VR head-mounted display, is highly effective at attracting interest which is an important point to encourage organizations to invest in new technologies.

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