I have original CT scans (.nii format) and a corresponding segmentation file (.nii format). Now I want to manually segment one/more organs using 3DSlicer and add to the existing segmentation file (.nii format). I am not sure how to perform this task. It will be helpful if you kindly suggest me the procedure.
If you can successfully import the existing segmentation into Slicer and the CT scan, then all you need is to create a new empty segmentation layer for your new organ segmentation, and continue from there.
Thanks a lot! It worked. 