How to create an implantation scheme (Stereotactic EEG) ?

This functionality is designed for advanced users.  It enables to draw a 2D or a 3D view of the depth electrodes.

Two options are available :

1. the location of the depth electrodes can be projected on a 2D view (sagittal, axial or coronal views). The entry and target point are represented with a colored disk. The body of the electrode is represented as a dot line. a red color corresponds to a depth electrode in the left hemisphere, a green color for a depth electrode in the right hemisphere).
2. the depth electrode can be represented as a 3D object in the 3D rendering window (see “3D rendering tools”). The user can rotate around the object to visualize its intersection with the brain and its direction in space.

Creation of the depth electrode table

The "depth electrodes" table is the place where the coordinate values of the depth electrodes are kept in memory.

1. Select a DICOM volume in the database (see “How to display a DICOM volume ?”),
2. Select the CA, CP, VB and VU points and reslice the volume according to Leksell points (See “How to reslice a DICOM volume ?”),
3. Navigate in the DICOM volume and choose the entry or target points of each depth electrode. If necessary, use a previously registered CT-scan in a second layer to show the location of each depthelectrode.
4. Select the “Target” or the “Entry” push button in the “depth electrodes” table to keep the coordinate values in memory. A new row is displayed in the table:

5. Edit the table (F2 or push button “Edit”) to rename the depth electrode, 
6. Repeat this procedure to register all the target and entry points of the depth electrodes,
7. Check that each electrode has a target and an entry point, and that the name of the target and the entry point are identical (column “Name”).

Creation of a 2D projection of the depth electrodes

When the user press the icon , the projection of the depth electrodes is displayed on each viewing window. The darker color corresponds to the target (red for depth electrodes on the left hemisphere, green for depth electrodes on the right hemisphere, see below:

When the user double-click on a row of the “depth electrodes” table, the viewing windows are automatically updated to the point coordinate registered in the table.

The user can navigate quickly between the target and entry points of the depth electrodes using the “move one step to the target point” or “move one step to the entry point” tool button at the bottom of the coordinates window. Each step is of 1.6 mm length according to the interval between two recording points of Dixi© depth electrodes. The current recording point number and the total number of the recording points are displayed.

see above :

A’ 1/14 = 

• Depth electrode’s name = A’,
• current position = recording point 1 (target point),
• total number of recording points = 14.

The name of the depth electrode is displayed on the left bottom of each target point. The left depth electrodes are colored in red, the right depth electrodes are colored in green.

Creation of a 3D view of the depth electrodes

It is also possible to create a 3D view of the depth electrodes and to display them alone or associated with 3D structures such as a volumetric representation of the gray matter or a volumetric  representation of the bone segmentation.

This functionality is accessible through the icon . Click on tab “Display depth electrodes - slices”. Check the box “depth electrodes” and press OK.

The depth electrodes are now displayed in the 3D viewing window “3D View”.See below the difference between the two ways of representing the depth electrodes:

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