Implementing highly efficient internal volume codec that is targeting the volumes upsampled using the NN-interpolation.  This is a critical function during the PET-4D to MR registration.
User optimally desires best available resolution for both registered volume, which is typically a MR resolution.  However, for high timepoint # the resulting volumes might reach upto 7 GB  (compressed with the regular FireVoxel compression).
This new codec will allow much higher compression of such registered PET volumes.

It is lossless.