Spacing irregularities

Dear organizers, In your dataset description, slice thickness are described to be of 3.27 mm, 3.00 mm or 5.00 mm for PSMA whole-body PET However by analyzing the Nifti files, I found the following spacing distribution: - 251 patients with 2mm spacing - 230 patients with roughly 3.3 mm spacing - 119 patients with 5 mm spacing

Is there a mixup between 3 and 2 mm z spacing?

Regards Zhack

Dear Zhack,

this is a valid observation. Indeed there is a difference in the slice thickness (which we extracted from the original dicoms) and the slice spacing one extracts from the nifti files. This is a result of the acquisition: The slab, in which the slices are acquired have a partial overlap with each other. This means that they are e.g. spaced 2mm, while each of the slices has a thickness of 3mm, but this information is only available in the original dicoms. The niftis already have voxels in the correct spacing. There is no mixup in the values, just the slight difference between slice thickness and slice spacing.

Best, Balthasar