Hi New Fei,
The subfield volume estimates are given in number of voxels of size 0.5mm isotropic - you'd need to divide by a factor of 8 to obtain measurments in mm^3.
The sum of the subfield volumes will not be the same as the total hippocampal volume in aseg.stats because the used computational methods are different. They should be close, though.
Hope this helps,
Koen
On Mon, Jun 27, 2011 at 1:25 PM, newfei@nmr.mgh.harvard.edu wrote:
Hi,
I have a couple of questions about hippocampal subfield segmentations generated using the kvlQuantifyHippocampalSubfieldSegmentations.sh script (recons performed using version 5.1).
The volumes obtained for each individual subfield are systematically larger than the total hippocampal segmentation volume generated by the recon-all. These volumes are also larger than the volumes in the paper (van Leemput, 2009) where CA1: 537-935 mm^3 and CA4/DG: 526 mm^3. For example in the dataset that I am working on , a typical subfield volume in the right hippocampus would be 2270 mm^3; CA2-3: 6477 mm^3; CA4-DG: 3796 mm^3.The sum of all subfields is 24437 mm^3.
c.f. hippocampal volume obtained from aseg.stats:3688 mm^3
First, are my values correct? Second, are the discrete subfield volumes supposed to match up with the hippocampal volume from aseg.stats?
Thanks, New Fei
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