itksnap binary package in Ubuntu Focal amd64

 SNAP provides semi-automatic segmentation of structures in medical
 images (e.g. magnetic resonance images of the brain) using active
 contour methods, as well as manual delineation and image navigation.
 Noteworthy features are:
 .
  * Linked cursor for seamless 3D navigation
  * Manual segmentation in three orthogonal planes at once
  * Support for many different 3D image formats, including NIfTI
  * Support for concurrent, linked viewing and segmentation of multiple images
  * Limited support for color images (e.g., diffusion tensor maps)
  * 3D cut-plane tool for fast post-processing of segmentation results

Source package