Mesh

Mesh Generation

We have a developed a series of software tools that allows us to reconstruct the arterial geometry for use with Nektar. The following is a brief overview of the arterial geometry reconstruction process.

Step 1: Acquisition of Geometric Data

Magnetic Resonance Angiography (MRA) and Computed Tomography (CT) combined with injection of a contrast into the arteries are widely used approaches for accurate and non-invasive acquisition of arterial geometric structure. In our study we use images of cross-sectional slices acquired by GE LX Signa Echospeed version 9.1 scanner at the Hadassah Hebrew University Medical Center.

Step 2: Contour Extraction

The images from step 1 are then used to extract the contours of arteries of interest. At this time a sub-region of the artery is interpolated onto a finer mesh where the actual contour extraction is performed. This has allowed us sub-pixel resolution to better capture the arterial geometry.

Step 3: Arterial Wall Reconstruction

At this point the arterial walls are constructed by interpolating the region between the contours extracted in step 2. Due to the relatively low resolution of CT/MRA images, we obtain a rough surface of the arterial wall. We employ an alternative bi-directional smoothing where each contour is smoothed in the azimutal and axial direction.

Step 4: Volume Mesh Creation

The data generated in step 3 is then fed into a series of scripts and imported into Griden, a commercially available mesh generator. At this point a straight faced mesh representation is available for computation.

Step 5: Curved Surface Creation

Elements created by Gridgen have flat faces. Representation of curved boundaries is acheived by projection of element faces on the arterial walls. Parametric representation of the arterial walls, saved in plot3D format and used for mesh generation, allows consistent mapping of a grid from computational to physical space.