Guideline viewer interpretation
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The document summarizes the key features and functionality of an epilepsy viewer software. It allows viewing patient MRI and EEG data in axial, sagittal, and coronal planes. EEG source localization overlays can be displayed on the MRI to visualize the estimated origin of seizure activity. Users can view the average spike waveform and localization for a cluster, as well as individual spikes. Controls are provided to change views, windowing, and select different image sets and overlays. The software aims to smoothly switch between views as data pre-loads for improved navigation of neurological data.
Guideline viewer interpretation
- 1. w w w . e p i l o g . c a r e
- 2. Starting the viewer Launch the viewer for a patient by clicking this icon. A new browser tab or window will open.
- 3. Data loading The blue bar indicates overall progress of data loading for this patient. When it is completely full, all data for this patient is loaded. The red bar indicates progress of data loading of one specific image – for example an MRI of the patient, or the EEG source reconstruction image of one of the detected spike clusters. To ensure smooth switching between different views and images while using the viewer, all data is pre-loaded when the viewer is started. As this requires a download of several 3D image volumes, it may take several minutes. This depends heavily on the internet connection speed. Progress of the data loading process is indicated by the progress bars.
- 4. Viewing planes The central (main) viewport is used to visualize each of the planes and the 3-plane view in detail. When the 3-plane view is displayed, it can be rotated in 3D by clicking and dragging inside the viewport. Zooming in and out can be done by using the mouse scrolling wheel. By clicking one of the small views in the right-hand column, this view is displayed in the central (main) viewport. Scrolling through the small views can be done by moving the slider on the blue, red and green bars. The viewer allows visualization in the axial (blue), sagittal (red) and coronal (green) plane. There is also a 3-plane view.
- 5. Viewing planes When the axial, sagittal or coronal plane is shown in the central (main) viewport, the mouse scrolling wheel can be used to scroll through the slices. Alternatively, this can also be done by moving the slider on the blue, red or green bar. Greyscale windowing can be changed by clicking and dragging within the viewport. When one of the small views is clicked, that plane is displayed in the central (main) viewport. The view that was shown in the central viewport is then shown in the small view. As an example, the axial plane has been clicked here. The 3-plane view, which was previously shown in the central viewport, is now shown in the small view at the top. By clicking this symbol, the original windowing settings can be restored.
- 6. Selecting image sets and overlays By moving the mouse pointer over the 'Imaging' bar in the left border, a different MRI of the patient (T1w, T2w) can be selected (if available). By moving the mouse pointer over the 'EEG' bar in the left border an overlay can be selected. For each detected spike cluster an overlay of the average spike is available, as well as of the 10 single spikes with the highest similarity to the average spike. Through this panel the pdf report can also be opened, and the patient-specific head model can be visualized by scrolling downward in the panel. Visualization of the EEG source imaging data is done by using overlays. These are color-coded images that are displayed on top of the patient MRI image.
- 7. Average spike The EEG of the average spike is displayed on the left-hand side. The color map of the overlay uses blue for low values and red for high values. This means that the red area is where the average spike most probably originated. By clicking the 'average' icon ( ) for one of the spike clusters, the EEG source estimation of the average spike is displayed as an overlay. The overlay can be switched on and off by pressing the space bar. The green crossmark indicates the maximum value of the EEG source estimation for the average spike. All imaging planes are automatically centered on this point.
- 8. Single spikes The EEG of the single spike is displayed on the left-hand side. By clicking this panel, the EEG of the next single spike will be shown in the panel. The viewing planes will also automatically be centered on the maximum point of EEG source estimation for that single spike. By clicking the 'singles' icon ( ) for one of the spike clusters, the maximum points of the EEG source estimation of the 10 single spikes with the highest similarity to the average spike. The maximum points of the EEG source estimation of all 10 single spikes are shown as green diamonds. The viewing planes are automatically centered on the maximum point of the single spike shown in the EEG panel.
- 9. Head model From white to black, the 6 different discriminated tissue types are shown: n Scalp n Skull n CSF n White matter n Grey matter n Air By clicking the 'head model' icon ( ) in the EEG panel, the patient- specific head model is displayed. This head model discriminates 6 tissue types and is used to perform EEG source estimation.