Diffusion MRI
File Formats
DICOM
DICOM Mosaic
Analyze
NIfTI
The NIfTI format was created by the Neuroimaging Informatics Technology Initiative at NIH. It is a superset of Analyze 7.5, re-purposing empty fields in the Analyze format to support more features. Fortunately for us, the NIfTI reference library is available in the public domain, and $G/src/nifti is set up to download the latest version (with make download), build it, and install it in $G/lib/nifti and $G/include/nifti. You might also try snooping around $G/doc/nifti to see what they have to say in their documentation.
The online documentation for NIfTI is also pretty sweet: