There's no NII format, that's the file extension of a format called NIfTI. NIfTI is not meant to be a replacement for DICOM. It's meant to be a quick and simpl

There's no NII format, that's the file extension of a format called NIfTI. NIfTI is not meant to be a replacement for DICOM. It's meant to be a quick and simple file format only for neuroimaging and only for research. It's missing countless features that are required for clinical use and it stores 3D data. So it's not a good format for xrays, ultrasounds, etc.