Boys and Toys and they all give different measurements of Grey Matter Volumes

Studies disagree on the location of grey matter (GM) atrophy in the multiple sclerosis (MS) brain.
AIM:To examine the consistency between FSL, FreeSurfer, SPM for GM atrophy measurement (for volumes, patient/control discrimination, and correlations with cognition).
MATERIALS AND METHODS:127 MS patients and 50 controls were included and cortical and deep grey matter (DGM) volumetrics were performed. Consistency of volumes was assessed. Consistency of association with cognition was assessed. Voxel-based morphometry (SPM-VBM and FSL-VBM) and vertex-wise FreeSurfer were used for group-level comparisons.
RESULTS:The highest volumetry ICC were between SPM and FreeSurfer for cortical regions, and the lowest between SPM and FreeSurfer for DGM. The caudate nucleus and temporal lobes had high consistency between all software, while amygdala had lowest volumetric consistency. Consistency of patients/controls discrimination was largest in the DGM for all software, especially for thalamus and pallidum. The penalized double-loop logistic classifier most often selected the thalamus, pallidum and amygdala for all software. FSL yielded the largest number of significant correlations. DGM yielded stronger correlations with cognition than cortical volumes. Bilateral putamen and left insula volumes correlated with cognition using all methods.
CONCLUSION: GM volumes from FreeSurfer, FSL and SPM are different, especially for cortical regions. While group-level separation between MS and controls is comparable, correlations between regional GM volumes and clinical/cognitive variables in MS should be cautiously interpreted.

MRI is used to measure lesion volumes and there has been a lot of interest in finding the volume of the grey matter lesions, which were historically missed by this approach for the longest period of time. 


Then it was found by histology after the pathologists realised that there is myelin in grey matter and that it goes in MS. 

So in this study they look at three types of analysis and they were different. However there is no way to really know, which is correct.
As there is no true correlation with pathology, it is impossible to tell and this is the problem of developing techniques using undefined natural disease.

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