Documentation/4.8/Modules/GeodesicSlicer

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Home < Documentation < 4.8 < Modules < GeodesicSlicer


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GeodesicSlicer logo

Introduction and Acknowledgements

Author(s)/Contributor(s): Frederic Briend (ISTS, UNICAEN), Antoine Nourry (UMS 3408)
Acknowledgements: This work was supported by CHU Caen.
Contact: Frederic Briend, <email>briend@cyceron.fr</email>
ISTS

The module has been developed based on ideas and feedback from the community. We would like to especially thank:

  • Dr. Olivier Etard, M.D., Ph.D., CHU de Caen.
  • Dr. Sonia Dollfus, M.D., Ph.D., CHU de Caen, header of ISTS.
  • Dr. Csaba Pinter, MSc, Queen's University.
  • Dr. Andras Lasso, Ph.D., Queen's University.

Module Description

This module calculates geodesic path in 3D structure. Thanks to this geodesic path, this module could draw an EEG 10-20 system.

Terminology

  • Mesh A mesh or polygon mesh is a collection of vertices, edges and faces that defines the shape of a polyhedral object in 3D computer graphics and solid modeling.
  • Shortest path In graph theory, the shortest path problem is the problem of finding a path between two vertices (or nodes) in a graph such that the sum of the weights of its constituent edges is minimized.
  • 10-20 EEG system The International 10-20 system is commonly used for EEG electrode placement and for correlating external skull locations to underlying cortical areas.[1]

Use Cases

The overall goal is to allow users to find the shortest paths between nodes in a graph and via the Dijkstra's algorithm to make 10-20 system. This module can be used for:

  • Stimulation in psychiatry
  • surgery measurement
  • 3D printing

Panels and their use

Geodesic Slicer. Panel set

Create a mesh

Image à insérer: "wiki_main_picture2.png"

A typical straightforward Geodesic Slicer workflow for consists of the following steps:

  1. Load a volume.nii.
  2. Enter the Geodesic Slicer module using either the toolbar or the Modules menu button.
  3. Create a mesh.
    • Wait a moment
  4. Use this mesh.
    • If your background was named 't1' the label will be called 't1-label'.
  5. Go to Parameters to find the shortest path or Make 10-20 EEG system electrode section.

Parameters to find the shortest path

  1. Source points.
  2. Input STL model.
    • Calculate in centimeter the shortest path via the Dijkstra's algorithm.
    • Draw the Dijkstra's algorithm shortest path.
      • Length (cm)

10-20 system electrode

Run the Dijkstra's algorithm to make the 10-20 system electrode distances

4 anatomical landmarks

Four anatomical landmarks are used for the essential positioning of the electrodes:

  • 1/the nasion
  • 2/the inion
  • 3/the pre auricular to the left ear
  • 4/the pre auricular to the right ear

Input STL model

This model required to contain a dense set of points.

Make 10-20 EEG system electrode

Make 10-20 EEG system electrode via the Dijkstra's algorithm.

  • Distance T3-Stim in the T3P3 axis are give in centimeters.

Information for Developers

The code is available at Github.

References

  1. Jasper, H.H. The ten-twenty electrode system of the International Federation. Electroencephalogr. Clin. Neurophysiol., 1958, 10: 370-375