Convert NII.GZ to IGES

Technical note

NII.GZ to IGES: what to expect from the conversion

The standard NII.GZ header has no fields for a patient's name, birth date or accession number, only an 80-character free-text description, which is one reason research pipelines convert DICOM to NIfTI before data is shared. That does not make every output anonymous. A head scan contains the face, and a 3D rendering of the volume can reconstruct it well enough to recognise someone, which is why public datasets are usually defaced first. Slices that pass through the front of the head carry the same risk. NII.GZ is made of pixels and IGES stores geometry, so the conversion traces the image into real lines, arcs and polylines. The result is editable in CAD: entities can be selected, snapped to and measured, rather than a bitmap wrapped inside a IGES container, which is what a viewer or a lightweight converter usually produces. It is still derived geometry, so expect contours rather than a structured drawing. Dimensions, blocks and meaningful layer names were never in the NII.GZ to begin with.