Grouping Regions of Interest (ROIs)
You may want to "group" several ROIs together in order to:
- Logically link the ROIs if together they form a particular anatomical structure.
- More easily change the annotation or
colour
of all the ROIs in the group.
- Create 3-D connected volumes-of-interest (VOIs) from ROIs in different slices.
Forming a group
An ROI group can be formed in one of two ways:
- Select all the ROIs to be grouped together. You
can select ROIs in several slices, as long as all the slices are
displayed. Then either use the keyboard accelerator CONTROL-G or select
Group
ROIs from the ROI Toolkit's Edit menu:
- Select
Create VOI Groups from the ROI Toolkit's Edit menu:
.
This will automatically create ROI groups from ROIs that form 3-D structures by connecting
overlapping ROIs across slices. This could be used, for example, if you have outlined anatomical
regions that stretch across multiple slices, and want to form each individual region into a
group. The result will be one or more groups of ROIs, each outlining a structure that is
connected in 3-D.
Editing a group
You can select all the ROIs in a group by selecting any of the ROIs in the group.
Note: care is required. If the group's ROIs extends across multiple slices, and those slice
are not visible on-screen, they other ROIs will still be selected. Changing a group's ROIs can
therefore have hidden consequences.
Once a group is selected, changing the annotation or
colour will change the annotation or colour of all
ROIs in the group. However, the shape of individual ROIs in a group cannot be changed: if shape
changes are needed, the ROIs must be ungrouped first.
To ungroup ROIs, either use the keyboard accelerator CONTROL-U or select Ungroup
ROIs from the ROI Toolkit's Edit menu:
When you save ROIs to disk, any groupings that exist
will be saved, and those groupings restored when you load
the ROIs
again.