Hello all, I want to calculate a Ventricle-to-Brain ratio (VBR) as a measure of parenchymal atrophy using Freesurfer version 5.3.0. I have tried to go about this using the aseg.stats output (using asegstats2table), but am running into inconsistencies.
The basic calculation for VBR is: (Total Ventricular Volume/Total Brain Volume) * 100 i.e. Bigler, E. D. (2013). Traumatic brain injury, neuroimaging, and neurodegeneration. *Frontiers in human neuroscience*, *7*, 395. What is the best way to get Total Ventricular Volume (TVV) and Total Brain Volume (TBV) for this calculation? I have tried several ways, which lead to different values: TVV = left lateral ventricle + left inf lateral ventricle + right lateral ventricle + right inf lateral ventricle + 3rd ventricle + 4th ventricle + 5th ventricle + choroid plexus which gives me a different result than TVV = BrainSegVol - BrainSegVolNotVent and for TBV TBV = TotalGrayVol + CorticalWhiteMatterVol which differs from TBV = BrainSegVolNotVent Thank you for your help, James Gullickson
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