Overlays in MPR

Overlays may be vizualized in the MPR view in a similar way to any image window in the nordicICE workspace. There is, however, one significant difference in the display of overlays in the image window and in the MPR window. In the image window overlays are interpolated into the coordinate system of the underlay. This means that parts of overlay volumes that extend beyond the bounds of the underlay volume are truncated. In MPR overlays may be displayed in their full extent. Overlays may extend above or below the underlay, e.g. to regions of the head where there are no underlay slices. One illustration is given below, in which one overlay is color coded in red and the underlay is greyscale.

Loading from file

Loading overlays in MPR:

  • On the main menu of the MPR window: Overlay -> Load...
  • On the popup menu of the MPR window: Overlay -> Load...

Any number of overlays may be loaded in MPR as long as enough memory is available on the computer system. When defining an overlay in MPR, i.e. when loading an image volume as overlay, the image window for which MPR was launched also loads the overlay volume. The opposite is true also, so that if an overlay is defined for an image window, either by drag-and-drop or by loading a new image volume as overlay, the corresponding MPR window loads the overlay volume.

If visualization of the palette color bar is enabled, as decribed in the section on MPR Viewing options, a color bar is displayed on the left hand side of the axial projection panel when an overlay is defined in the MPR window. This color bar shows the range of overlay intensity values in the current overlay.

Modifications

Modifying overlays in MPR:

  • On the main menu of the MPR window: Overlay -> Modify...
  • On the popup menu of the MPR window: Overlay -> Modify...

As for overlays displayed in an image window in the nordicICE workspace one may modify various settings with the overlay. The topic is treated for the main window in the section Modify image overlays.

Deletion

Deletion of overlays in MPR:

  • On the main menu of the MPR window: Overlay -> Delete
  • On the popup menu of the MPR window: Overlay -> Delete

When overlays are deleted from the MPR window, the overlay is also removed from the corresponding image window, and vice versa.

Zero below threshold

Zero overlay intensities below threshold in MPR:

  • On the main menu of the MPR window: Overlay -> Zero below threshold
  • On the popup menu of the MPR window: Overlay -> Zero below threshold

The user may zero pixel intensities in the overlay that are below the threshold specified in Settings' Win L/W Presets tab.

Tips:

  • Many of the actions described above are accessible using keyboard shortcuts.