Neurological imaging tool FreeSurfer, curated at the Martinos Center for Biomedical Imaging, is a commonly-used open-source software tool employed by researchers to measure cortical thickness and volume of varying brain structures from the MRI scan of a patient. Recent research has shown that the calculations, given the same input, can vary up to 15 percent between different versions of the software, and up to five percent between Linux and OSX. No explanation has been given by the curators for the phenomenon.
