Another goal was to reduce the uncertainty about diverse ANALYZE™-7.5 extensions used in this community. The NIfTI-1 format has been carefully designed so that unmodified FMRI analysis programs that read ANALYZE™-7.5 files are likely to work with NIfTI-1 files for example, the NIfTI-1 header is still 348 bytes long. → i.e., contains 'extra' data not defined in ANALYZE™-7.5. (9) 'Magic' string indicates if header is NIfTI-1 compliant: → 21 types of statistics are encodable parameters can be global or voxel-dependent. (8) Codes and parameters for data 'meaning' (e.g., values are t-statistics with 23.7 DOF): (7) Affine data scaling (i.e., true-data-value≡α*data-in-file+β α, β stored in header).

(6) Standardized way to store vector-valued datasets (e.g., a matrix at each voxel). (5) 'Complete' set of 8.128 bit data type codes. (4) Codes to indicate temporal and spatial acquisition ordering for MRI. (3) Codes to indicate units of spatial and temporal dimensions.

(2) Codes to indicate spatial normalization type (e.g., MNI-152). → global coordinates are + x=Right, + y=Anterior, + z=Superior. → one general affine transform, to indicate mapping to a 'normalized' space → one orthogonal transform, to indicate orientation/location of data in scanner coordinates (1) Two affine coordinate definitions relating voxel index to spatial location:

Since the ANALYZE™-7.5 file format (.hdr/.img file pairs) is simple, widely used, and contains some unused/little-used fields, for the first phase we decided to modify this format to add features that the DFWG agreed were highly desirable for FMRI analysis purposes. The DFWG decided to proceed in two phases: near- and long-terms. The Data Format Working Group (DFWG) within NIfTI was chartered to deal with the particular issue of data interoperability that is, making it simpler to interchange image (etc.) data between analysis packages. The problem of interoperability of neuroimaging data analysis software is being addressed by the NIfTI (Neuroimaging Informatics Technology Initiative) task force. Robert W Cox 1, John Ashburner, 2, Hester Breman, 3, Kate Fissell, 4, Christian Haselgrove, 5, Colin J Holmes, 6, Jack L Lancaster, 7, David E Rex, 8, Stephen M Smith, 9, Jeffrey B Woodward, 10, Stephen C Strother, 11ġNIMH/NIH/DHHS/Bethesda, 2FIL/London, 3Brain Innovation/Maastricht, 4U Pittsburgh/Pittsburgh, 5MGH/Charlestown, 6SGI/Mountain View, 7RIC/UTHSCSA/San Antonio, 8LONI/UCLA/Los Angeles, 9FMRIB/Oxford, 10Dartmouth College/Hanover, 11U Minnesota/Minneapolis and DFWG Chair A (Sort of) New Image Data Format Standard: NIfTI-1

Human brain mapping submission