Centerline computation problem - straight lines

Hi all.

I have been working with 3D slicer for a few months now. I am trying to isolate coronary arteries from CCTA scans, get the centerlines and quantify some geometric features I need for further analysis.

As far, I have managed to get some adequate segmentations of the coronaries and succesful network model - curves - properties. What I cannot seem to get is accurate centerlines. Specifically, while I get an (almost) correct centerline model, the centerline curves constructed are not good. I’m attaching an image for reference. Could someone explain why do I get this result? I have messed with the endpoints (both manually placed and auto detected) and I always get these weird straight lines. When computing the centerline curves, I get this warning:

[VTK] Warning: In vtkDelaunay3D.cxx, line 526
[VTK] vtkDelaunay3D (00000236E6A111E0): 1 degenerate triangles encountered, mesh quality suspect

Here is an image of the constructed centerline tree:

As a reference, the centerline model is pretty accurate:

I’m trying to get the centerline tree geometry quantification because I want to compute angles of bifurcations along other features, and after some research I found out it is better suited for this task (reference post : Separating centerline metrics ).

My questions are:

  • why do I get these weird straight lines. How can I access this “mesh quality” error? How can I fix it?
  • what is the correct way to place the endpoints if there is some preffered manned that is.
  • Does it matter that in the same segmentation also lives the Right Coronary Artery?