Generating constant wall thickness of a patient-specific geometry (aortic dissection)

[Malte R.-P.]

Hi,

I have a patient-specific geometry of an aortic dissection which consists of the inner aortic wall only (.stl - file). To perform a finite element analysis on the aortic wall (solid domain) I need to generate a constant wall thickness to the existing geometry of an aortic dissection with its false and trum lumen. Is there any possibility to do this with SimVascular?

I hope that someone can help me out!

All the best,
Malte

[Kathrin Baumler]

Hi Malte,

There is no straight-forward way to do this kind of stl-manipulation in SimVascular at the moment.
I would recommend using meshmixer (http://www.meshmixer.com) which is free for download.

A possible workflow in Meshmixer would then look like this:
1) Import your stl file into meshmixer
2) Choose the "Make solid" filter (Edit--> Make solid), and set the following options:
Choose the cell size for "Solid accuracy" at or below your current spatial resolution
Choose the cell size for "Mesh Density" at or below your current spatial resolution
Choose "Offset Distance" to be your desired wall thickness

3) you can play around with the other options, especially "sharp edge preserving" or "accuracy" are sometimes helpful.
4) Clean up the resulting file. (especially if some branches are very close together, they may intersect after the extrusion, so watch out for that).

Hope that works for you, let us know if you have any follow-up questions.
Best,
Kathrin

[Kathrin Baumler]

... Oh and I should add:
If you see a dent in the extruded mesh where the flap was, then you'll have to clean up those regions manually, either by "erasing and refilling" cells in those areas or by using smoothing or sculpting tools in meshmixer..

To then get your final wall model, use your original stl as the inner wall and the extruded model as the outer wall. To get the closed rings at inlets and outlets it might be best to use a plane cut tool.

You can find documentation about creating the corresponding volume meshes in SimVascular - and some more tips on how to use meshmixer - on the website at
https://simvascular.github.io/docssvFSI ... _meshmixer

[Malte R.-P.]

Hi Kathrin,

thank you so much for your quick and comprehensive response! I will carry out your suggestion directly.

All the best,
Malte