ROI Tool

The term Region of Interest (ROI) is used throughout the tutorial as a synonym for a "Mask", "Binary Mask", "Segmentation" or "Volume of Interest". Technically, it is a binary 3D volumetric image matrix, which is quite similar to 3D image apart from the fact that voxel values are binary (on or off). Thus, a ROI has also the same properties as image (like resolution and matrix size).

ROIs can also be just 2D, however, one has to be remember that the 2D slice has also a position in 3D space, which can sometimes be confusing.
ROIs are close to what is represented by DICOM SEG objects. 

 

To open the ROI-tool just go via the toolbox menu of the vertical iconbar or use the shortcut via the "pen" icon:

                           

This opens the following toolbox window, which contains the access to all functionalities of the ROI-tool

On the right you have list of currently opened ROIs togeter with information about matrix size and patientID/studyID. There is also information about the size of ROI and several tool icons, which are explained in the following

 

	focuses the position of the viewer to the center of gravity of the current ROI
	turns the ROI to be the "current ROI" on which currently is drawn on
	toggles the visiblity of the ROI in all viewports
	open several options to modfiy ROIs (see below: ROI operations)
	save the ROI (upload to server)
	downloads the ROI to your local computer
	erases/clears all on voxels of the ROI
	deletes the ROI from workspace

 

 

Creating a ROI

 

Pen Options

 

 ROI operations  

• Morphological Operations: NORA provides the typical 4 operations (erosion, dilation, opening and closing) using a 6-neighborhood in the slicing of the ROI matrix, i.e. the size of the neighborhood varies depending on the underlying matrix size.
• Set Operations: NORA provides intersection, union and set difference. Select

ROI statistics