## 4 Applications and Limitations  
VR has been used in neurosurgery to simulate the operating room experience so that surgical residents can rehearse cases before operating on live patients to promote their surgical skills and reduce patient risk [34]. Furthermore, VR has been used to provide preoperative plans for invasive treatment strategies and improve surgical outcomes [35]. The current CFD-VR method is a more suitable use for the latter purpose. The main difference between VR simulators and CFD-VR visualization in cerebral endovascular neurosurgery is that the first one is more focused on the implementation of the intervention, while the second one illustrates the consequences of the proposed method and conditions after treatment. Notably, the other important aspect of the current CFD-VR method is its applicability to design a unique patient-specific treatment method for every patient. The neurosurgeon could use computed tomography (CT) and/or magnetic resonance imaging (MRI) to build each patient's 3D aneurysm model (8). Then, the model could be transferred to computer-aided design (CAD) software and, using the generated model, the computational fluid dynamics simulation can be carried out for the cases where flow diverter devices with various geometries are used and deployed with varying positioning. The VR-visualized results would indicate the effect of various FD devices on blood flow and important hemodynamic parameters and produce significant insight for the neurosurgeon when selecting and positioning these kinds of tools. This could lead to a reduction in technical errors and greater treatment efficiency. Although the benefits are evident, the application of VR in neurosurgery faces several limitations. The first practical challenge is the usability of VR systems that need to be adopted into the surgical environment and require a minimum technical proficiency [35]. The development of robust VR software can be challenging and can require high-end computer systems with advanced graphics cards, high-resolution displays, and accurate tracking systems [36; 37]. In addition, professionals from various fields need to cooperate when designing VR software for application in clinical settings. These factors may increase the costs and influence the economic feasibility of the widespread use of virtual reality \begin{table}
\begin{tabular}{c c c c} \hline \hline  & \begin{tabular}{c} **Aneurysm-Averaged** \\ **Wall Shear Stress on the** \\ **Wall of the Sac (Pa)** \\ \end{tabular} & \
\begin{tabular}{c} **Aneurysm-Averaged** \\ **Kinetic Energy Inside** \\ **the Sac (m\({}^{2}\)/s\({}^{2}\))** \\ \end{tabular} &
\begin{tabular}{c} **Turnover Time** \\ **(s)** \\ \end{tabular} \\ \hline Without-stent & 0.771 & 0.00247 & 0.82 \\ With-stent1 & 0.963 & 0.00340 & 0.83 \\ With-stent2 & 0.356 & 0.00146 & 1.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Time-averaged hemodynamic parameters. Figure 22: Point clouds colored by dimensionless pressure, Without-stent, \(t=t2\). technology in neurosurgery [36]. Furthermore, neurosurgeons may be hesitant to adopt the proposed VR methodology because VR applications lack comprehensive technical standards [34; 35]. Furthermore, this type of technology may cause the gradual shift in decision making in surgery from human surgeons to computers, which could create ethical issues related to the use of this technology [34]. The above issues concerning VR surgery simulators are not as critical in relation to the current CFD-VR visualization method. On the one hand, due to the accelerating technology advances, low-cost and low-weight head-mounted displays and more powerful computer and graphics processors are available for rendering CFD three-dimensional images and animations. On the other hand, only CFD experts can work on CFD-VR visualization, so the costs of the current technology are reasonable.