We are writing on behalf of the Data Format Working Group (DFWG), a committee set up under the Neuroimaging Informatics Technology Initiative (NIfTI, [nifti.nimh.nih.gov]), which is jointly sponsored by NIMH and NINDS. We have been charged with arriving "at a technical solution to the problem of multiple data formats in fMRI." We have met several times and decided that one of our first priorities is to describe and attempt to merge the variants of the ANALYZE(TM) 7.5 image header that are being used by the developers of the major fMRI data analysis packages.

We have defined a compromise data format, dubbed NIfTI-1, that is based on these variants and is "mostly compatible" with the ANALYZE(TM) 7.5 header, while using many of the "unused and lesser-used" fields for fMRI-specific purposes. Developers of five of the major fMRI data analysis packages (FSL, SPM, AFNI, BrainVoyager, and FreeSurfer) have agreed to use this compromise format in the future, and will support both input and output of the NIfTI-1 format. A considerable effort was required to reach agreement with all of these developers. Given the extremely limited space in the 348 byte header, it is unlikely that any substantial changes will be possible in the NIfTI-1 format if we are to retain the support of all five packages.

We envisage NIfTI-1 replacing the current range of ANALYZE 7.5 variants both for file interchange and data storage. NIfTI-1, while still limited, contains a considerably richer set of metadata than exists in the ANALYZE-based formats.

As of this message, the NIfTI-1 format specification, demonstration programs, and related documents are being released to the general neuroimaging community on the DFWG website [nifti.nimh.nih.gov]
along with an interactive forum for comments and discussion. The DFWG committee will next meet in early May 2004, and any comments you care to make and would like to have considered at the next committee meeting should be received by April 15, 2004.

Please feel free to pass this message along to any other person you think might be interested. Comments and questions should be directed to the NIfTI-1 interactive forum, and not to DFWG committee members via e-mail, and not to the AFNI message board. The full list of DFWG committee members can be found at the DFWG website.

Stephen Strother, PhD
Chair, Data Format Working Group
Professor of Radiology
University of Minnesota

Robert W Cox, PhD
SSCC/NIMH/NIH/DHHS/USA/Earth

[nifti.nimh.nih.gov]