You can draw an oval Region of Interest (ROI) on a slice, and the ROI will then be shown on all of the images in the group, displaying area measurement, average pixel value, standard deviation and range of pixel value. The graphic is added automatically as a bookmark. Open the Bookmark list to see its details.
1. From the Viewer, select an image.
2. In the Graphics tab of the toolbar, select Persistent Oval 
from the ROI drop-down in the Measurements ribbon.
3. Click on the image where you want the ROI to start.
4. Click again when the ROI is defined.