Determination of an estimate point of rupture for intracranial aneurysms using mathematical models applied to fluids dynamics
Authors: Figueredo Luisa Fernanda , Tobar Juliana Fernanda , Gomez Laura Fernanda , Pedraza‐Ciro Maria Camila , Lopez‐McCormick Juan Sebastian , Rueda Roberto Javier , Mejia‐Cordovez Juan Armando 
Published: June 2021

Background

Intracranial aneurysms represent a potential risk factor for various comorbidities, mainly associated with its rupture. Available information for aneurysms intervention is changing a paradigm and now, the decision of operating or not, varies in co‐dependence with the patient. We present the preliminary results of a potential tool that shows high rupture probability areas, predicting early rupture risk, also as an alternative for surgical planning.

Objective

To describe the mathematical models that best characterize the blood flow in an aneurysm and implement them through computational simulations to define the hemodynamic properties in terms of pressure, velocity and shear rate in artery walls.

Materials/Methods

Using the software ITK snap, an angioscanography of a patient from the Fundación Santa Fe de Bogotá was segmented. This program implements the methodology of snake evolution to obtain a 3D model by creating an estimated anatomical form and calculating internal forces of the image gradient inside of a closed curve. This gradient is determined by the pixel intensity on every point of the closed curve, which can be enhanced by contrast made previously to the volume. Secondly, with the purpose of having a non‐restriction model, the software Meshlab was used. This software edits and processes a model that is composed of triangular meshes. For this, a three Laplacian smooth was implemented in the final model. Finally, the blood flow within an aneurysm was modeled using the Comsol Multiphysics software assuming that blood behaves like Newtonian fluid with laminar flow, density of 1000 kg/m3 and a dynamic viscosity of 0.0035 Pa * s, governed by conservation of momentum and mass equations. For the simulation, a free tetrahedral mesh was used, with refinement at the edges of the geometry, whose size was defined by the previously established fluid dynamics.

Results

For our first model, the highest stress levels were found at two points of an aneurysm: at the entrance and at the wall, where the highest velocity of blood flow was present. As for the velocity of the blood, it was reduced in the model, meaning that recirculation was present which is to be expected when dealing with aneurysms. Lastly, the shear rate was highest at the neck of the aneurysm and its lowest degree inside the aneurysm.

Discussion

The mathematical models describe the behavior of different variables. The simulation of blood flow within an aneurysm model obtained from diagnostic images of a real patient generates a good approximation to the behavior of blood flow in real life.

Conclusion

Pressure, speed and shear stress on the arterial wall are the main factors involved in the development and possible rupture of an aneurysm. The mathematical models of this preliminary study will be implemented on a larger database. By doing so, a method capable of predicting the point in which there is a greater probability of rupture in an aneurysm can be developed, based on its hemodynamic properties.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.