NIFTI file format

Like DICOM, NIFTI, which stands for Neuroimaging Informatics Technology Initiative, is an open standard that is available at https://nifti.nimh.nih.gov/nifti-2. The standard has started out as a format to store neurological imaging data and has slowly seen a larger adoption across other types of biomedical imaging fields.

Some things that distinguish NIFTI from DICOM, though are:

• NIFTI is optimized to store serial data and thus can store entire image series (and even study) in a single file.
• NIFTI is not generated by scanners; therefore, it does not define nearly as many data elements as DICOM does. Compared to DICOM, there are barely any, and mostly they have to do with geometric aspects of the image. Therefore, NIFTI files by themselves can not constitute a valid patient record but could be used to optimize storage, alongside some sort of patient info database.
• NIFTI files have fields that define units of measurements and while DICOM files store all dimensions in mm, it’s always a good idea to check what units of measurement are used by NIFTI.
• When addressing voxels, DICOM uses a right-handed coordinate system for X, Y and Z axes, while NIFTI uses a left-handed coordinate system. Something to keep in mind, especially when mixing NIFTI and DICOM data.

Further Resources

• Background and history of the NIFTI: https://nifti.nimh.nih.gov/background/
• The most “official” reference of NIFTI data fields could be found in this C header file, published on the standard page: https://nifti.nimh.nih.gov/pub/dist/src/niftilib/nifti1.h or on this, slightly better-organized page: https://nifti.nimh.nih.gov/nifti-1/documentation/nifti1fields
• A great blog post on NIFTI file format: https://brainder.org/2012/09/23/the-nifti-file-format/

New Vocabulary

• NIFTI - Neuroimaging Informatics Technology Initiative, is an open standard that is used to store various biomedical data, including 3D images.