Atlas-based VOI Statistics

When an image series has been loaded for which a suitable atlas exists, its use for VOI statistics is straightforward. First activate the VOI functionality, select the Template tab, and chose the template in the list on the Atlas pane.

The atlas description is read and the list of VOI labels populated. Initially, all regions are selected, and an overlay on the images marks their locations. The overlay can either show an open or a filled pixel raster, depending on the setting of the radio box above the Ovr check. To hide all template VOIs at once please un-check the Ovr box on the Template tab. To stop using the template VOIs select the X tab next to Atlas.

VOI Selection

Only the selected atlas regions are shown as VOIs and used for statistics calculations. The usual operations can be applied to select or de-select entries in the VOI list.

• CTRL+A: Select all entries.
• CTRL+Click: Check or un-check an entry without changing the others.
• SHIFT+Click: Select the range until the clicked entry.

VOI templates can co-exist with the standard VOI contours.

To modify the contour VOIs , select the List tab and use all of the functionality described for the contour VOIs sections above. Statistics calculates the statistics of the contour VOIs and the active template VOIs.

Using Atlas VOIs as Masks

In addition to using template VOIs for statistics, they can also be applied for masking contour VOIs. Illustrated below are a contour VOI from the List tab and a selected VOI from the Template tab which overlap. The indication in the O operation column is N for normal operation.

If the operation mode is changed to * for Mask operation by the indicated button, the atlas VOI acts as a mask for the contour VOI as shown below.

Atlas Visualization

If the 3D option has been purchased, the atlas can be rendered using the View all in 3D button located below the VOIs list.