If the volume loaded and displayed in the first slot is a single volume (i.e, not a time-series) and is not a floating point format volume (i.e., not a float or double volume), the contents of the first volume can be replaced by a mask corresponding to a particular traced structure and then saved as follows:
The resulting file will be in the same format at the volume originally loaded in the first slot, including all header information. The mask values corresponding to the structure will be set to the highest value representable by the data format, and all other values will be zero.
If the first volume is not editable (because it is a time series or because it is a floating point format), you can load an editable volume with identical dimensions and voxel sizes in the first slot, keeping the current contours when prompted, at which point you will be able to create masks. However, it would be safest to save your contour data first so that you can reload it with an editable volume later if something goes wrong.
You do not need to reload the original volume to create a mask for a second structure. Simply select the next structure and choose "Create Structure Mask" again.
If you view the mask and original trace with magnification, you may see discrepancies produced by rasterizing the image and also artifacts related to interpolation (unless you are using nearest neighbor interpolation). The discrepancies are created when rasterizing high resolution traces back onto the lower resolution images. You are strongly encouraged not to measure structure areas or volumes by counting non-zero voxels in masks. MultiTracer should produce more accurate measures of volumes and areas by computing them directly from the high resolution traces. The intent in making masks available in MultiTracer is to allow generation of regions-of-interest for other tools that do not support contour data.
©2001-2012 Roger P. Woods, M.D.
Modified: August 29, 2012