Region of Interest Appearance

How Regions of Interest Look

A Region of Interest (ROI) can be in one of several "states":

Unselected. The ROI is shown with a red outline.
Selected. The ROI is shown with a light blue outline.
Selected and editable. The ROI is shown in light blue, and also has centre, edge and corner "handles".
Selected, editing outline. Irregular and Spline ROIs in this state are shown with handles at points around the outline.
Deleted. The ROI is shown in dark blue. A deleted ROI may not be changed in any way.

Note: These colours are configurable in the user preferences.

These five states are shown below for a small irregular ROI:

The appearance of an ROI in different states.
roi_unselected roi_selected roi_editable roi_edit_outline roi_deleted

Unselected Selected Selected and editable Editing outline Deleted

The appearance of an ROI in different states.

Unselected	Selected	Selected and editable	Editing outline	Deleted

Note: Deleted ROIs are not normally visible. To view deleted ROIs select the Show Deleted ROIs check-box in the View menu of the ROI Toolkit window: show_deleted_rois .

You change from one state to another according to these rules:

To select an ROI, click on the (red) outline of the ROI. When selected, the statistics about the ROI are shown, if the "Show Statistics" is checked:
To deselect an ROI, click anywhere in the display window.
To select more than one ROI, press the "Shift" key down as you make your selection with the mouse. When more than one ROI is selected, combined statistics about all selected ROIs are shown.
To select all ROIs, or those in the selected slice, use the keyboard shortcut Ctrl-A.
When the ROI toolkit is in Edit Mode, a selected ROI is automatically editable. When in View Mode an ROI is never editable.
If you have selected an Irregular, a Curved Line, Closed, or Open Spline ROI, you can click again on the outline of the ROI to change to Editing the Outline. You can also edit the outline of an Irregular or Spline ROI by selecting Edit Outline from the Edit menu in the ROI toolkit, or using the keyboard accelerator "Control-O".
An ROI is marked as "Deleted" when it has previously been saved to disk, and then retrieved and deleted. Deleted ROIs are only visible if you turn on the Show Deleted ROIs check-box in the View menu of the ROI toolkit. See the audit trail section for more information.

You can also select ROIs by lassoing them. To lasso one or more ROIs, hold down the left mouse button and drag the mouse to enclose ROIs as shown below. Any ROIs within the red dotted lasso rectangle will be selected when the mouse button is released.

Lassoing ROIs with a mouse drag gesture.

To learn how to edit ROIs see the ROI editing section.

You can select ROIs that are connected (overlap) in adjacent slices by first selecting one or more ROIs, and then pressing the SelectAcrossSlices button (keyboard accelerator: j). This button only becomes active when there are ROIs in different slices. This action checks in slices adjacent for ROIs that connect, or overlap with the selected ROIs, and also selects the overlapping ROIs. It also checks for overlapping ROIs in adjacent to these newly-selected ROIs and propagates across all slices to select ROIs that form connected regions in 3-D.
Note: although ROIs may be selected by this method across multiple slices, this may not be evident if the slices containing selected ROIs are not visible on screen. Care must be taken when performing operations on ROIs selected in this way, since any changes to ROIs may not be evident.

ROI Colours

The default ROI colours depend on the state of the ROIs, as shown above. However, you can also set the colour of ROIs (including the colour of Text ROIs) individually. To set the colour of an ROI, first select it. Then choose the colour from the menu of possible colours in the ROI Toolkit: roi_colours_menu .

There are eight colours to choose from, labelled Colour 1 to Colour 8, as well as the default colours as above. Although you are restricted to one of eight colours, you can choose any eight colours to be your colour palette. To choose a different palette of eight colours, set them in the user preferences. If you choose a colour from the menu before creating an ROI, the newly-created ROI will have the chosen colour.

When you explicity set an ROI colour from the palette, it will be displayed with that colour regardless of its state. Only the handles that appear on an ROI will show you that it is selected.

Note: if you save ROIs to disk with certain colours, and then change your palette of colours, when you reload the ROIs from disk, they will be shown with different colours from the new palette.

You can use a keyboard accelerator to set the colour of a selected ROI: press the digits 1 to 8 to set a colour from the palette, or the digit 0 (zero) to set back to the default colour.

Edit and View Modes

View Mode provides a way to view previously-defined ROIs in a safe way, without the possibility of accidentally changing them. When in View Mode, ROIs may not be edited in any way. To switch between Edit and View Modes, select the appropriate button at the top of the ROI Toolkit frame:

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