BrainVoyager v23.0

Volumes-Of-Interest

The volume renderer can also visualize volumes-of-interest (VOIs), which provides useful additional information int for visualizing volumes. When opening the volume renderer, the program checks whether a volume-of-interest file is linked to the current VMR dataset. If this is the case, the volume-of-interest file is loaded. Alternatively, one can use the Load VOIs button in the Volume Renderer Controls panel to load any (matching) volume-of-interest file. If a VOI file has been loaded, the Volumes-Of-Interest (VOIs) panel is displayed automatically (see left side in screenshot below), and it can be toggled using the VOIs Panel entry in the context menu of the Render View.

The names of the available VOIs are listed in the VOIs list at the top of the VOIs panel. A VOI can be selected by checking the selection box on the left side of its name. It is also possible to show or hide all available VOIs using the Show All or Hide All buttons below the VOIs list (see red arrow in the screenshot below).

VOIs are included in volume visualizations by rendering voxels hit by volume rendering rays in the color defined by the respective VOI. This includes also anatomical slicing as shown in the screenshots above. Note that unselected VOIs are also somewhat visible in case that the Hidden transp value is set larger than 0.0 (default value: 0.1).

Besides adding useful information for visualization, VOIs can also be used to dynamically remove volumetric regions from volume rendering by turning on the Select VOIs mask anatomy option. An example is demonstrated below where a VMR dataset is shown on the left in combination with a "defacing" VOI. The VOI and VMR are both transformed in MNI space (the VOI is available in the 'Docoments/BrainVoyager/MNITemplates' folder).

On the right side the Select VOIs mask anatomy option has been turned on (see red arrow) temporarily removing the respective region from volume rendering. This possibility allows to create complex 'cuts' of a volume that are not achievable with standard slice planes.