Segmentation and advanced processing

To display a specific feature within the image, you can define what part of the exam data should be visible, and what part should not. The main tools you will use for this are:

• Thresholding: to extract a region of interest by selecting a range of voxel values that represents a specific tissue or anatomical feature.
• Scalpel: to perform cuts in the 3D volume to define the region of interest.
• Paint: to mark the region of interest with colored paint and then display only this region.
• Auto–select: to select an object and add it on or remove it from the selected view.

The process of removing structures is sometimes referred to as volume segmentation because the 3D volume is segmented, or split, in two parts: the volume of interest that is currently displayed, and the remainder that is removed from view.

After volume segmentation, the displayed part of the 3D model consists of one or more 3D objects. A 3D object is a part of the 3D model that is separate from other parts. Two 3D objects are separate if there is at least one voxel width of empty space between them.

Sometimes, two seemingly separate objects still act as one, because they are still connected somewhere by a bridge of voxels. It is also possible that a seemingly single object turns out to consist of two or more parts, separated by narrow gaps. The tools on the Advanced Processing screen can help you to deal with these effects.

For an overview of the segmentation icons, see Toolbar: segmentation icons