afni.nimh.nih.gov

Glad you figured it out. It looks like you're looking at single slice data, so there's a little strangeness in that the third dimension has to be 1, in keeping with the NIFTI specs. What software produced this?

"... NIFTI-1 reserves dimensions 1,2,3 for space (x,y,z), 4 for time (t), and 5,6,7 for anything else needed."