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---
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layout : default
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- title : NFT
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- long_title : NFT
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parent : NFT
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grand_parent : Plugins
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+ render_with_liquid : false
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+ title : Chapter-02-Head-Modeling-from-MR-Images
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+ long_title : Chapter-02-Head-Modeling-from-MR-Images
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---
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The steps of head modeling are segmentation, mesh generation, and
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co-registration of electrode locations with scalp surface. User may also
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generate a source space to be used in the solution of the inverse
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problem. Figure 2 shows the steps of head modeling using MR images.
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- <center >
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![ Figure 2: steps of head modeling using MR images] ( NFM_Toolboox_UsersManual_html_2aaa1b22.gif )
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- </center >
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Each step in realistic head modeling is implemented as a separate GUI
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module reachable from the main menu. These modules are described in the
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following sub-sections.
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panels. The available choices are the MR volume, the filtered volume or
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various stages of segmentation.
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- <center >
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![ ] ( NFT_from_MRI_segmentation.png ) .....
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![ Figure 3: Interface for segmentation] ( NFT_segmentation.png )
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- </center >
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The panel on the right of the segmentation GUI shows the segmentation
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steps that will be performed on the volume in order:
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images. The result of Brain segmentation can be seen by selecting “Brain
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Mask”.
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- <center >
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![ Figure 4: Interface of segmentation during setting lowest point
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for cerebellum.] ( NFT_cerebellarlowpoint.png " wikilink ") ......
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![ Figure 5: Interface of segmentation during a seed point
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selection on WM.] ( NFT_WMpointselection.png " wikilink ")
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- </center >
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### Outer skull segmentation
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For outer skull segmentation, seed points for the eye lobes are selected
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to click on eye lobes. Once the eyes are selected the outer skull is
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segmented and can be seen by “Outer skull mask”.
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- <center >
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![ Figure 6: Interface of segmentation to select an axial slice where the eyes are clearly observed.] ( NFT_eyeselection.png " wikilink ")
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- </center >
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- <center >
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![ Figure 7: Matlab figure to click on eye lobes.] ( NFT_eyelobes.png " wikilink ")
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- </center >
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### Inner skull segmentation
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Inner skull segmentation does not require any user input. After the
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of the mesh file is given in [ Appendix A] ( /NFT_Appendix_A " wikilink ") .
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The mesh generation process is described below.
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- <center >
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![ ] ( NFT_from_MRI_mesh_gen.png " wikilink ") .....
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![ Figure 8: Interface for mesh
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generation.] ( NFT_meshgeneration_ui.png " wikilink ")
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- </center >
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Mesh Generation module creates triangular meshes that fits the
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boundaries of the segmentation. The aim is to approximate the geometry
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parametric inverse problem solution to find a coarse estimate of the
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dipole position.
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- <center >
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![ ] ( NFT_from_MRI_source_space.png " wikilink ") .....
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![ Figure 9: Interface for source space generation.] ( NFT_sourcespacegen.png " wikilink ")
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- </center >
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Co-registration of electrode locations
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--------------------------------------
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@@ -287,12 +264,9 @@ the electrode positions change. Therefore, the co-registration output is
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specific to a session. The result of electrode co-registration is saved
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as Session_Name_Subject_Name_headsensors.sens in ASCII format.
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- <center >
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![ ] ( NFT_from_MRI_coreg.png " wikilink ") ....
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![ Figure 10: Interface for co-registration.] ( NFT_coregistration.png " wikilink ")
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- </center >
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Head Modeling using Template Warping
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------------------------------------
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In Figure 11 the interface for warping module is shown.
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![ ] ( NFT_from_Warping.png " wikilink ") .....
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![ Figure 11: Interface warping of a template head model.] ( NFT_warping_ui.png " wikilink ")
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- </center >
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------------------------------------------------------------------------
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References
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