We have a study where subjects are scanned one, and a second time 6 months later. I am looking for changes between the two time point and often times there is a large difference in the "number of defect holes prior to fixing" within the same subject.
Can anyone comment on the significance of this? Given the same brain being scanned 6 months later, how / why is there such a difference?
[Logo] Brad J. Matushewski, M.Sc., R.Kin., CSEP-CEP. Laboratory for Brain & Heart Health School of Kinesiology Western University Room 402, Arthur & Sonia Labatt Health Sciences Building London, ON, Canada, N6A 5B9 Tel: (519) 661-2111 x 89066 Fax: (519) 850-2447
Hi Brad
number of defects is probably a pretty unstable measure. You can change the segmentation of a single WM voxel and cause a defect to appear/disappear. You can also have differences in scan quality due to e.g. motion that can change things. Are the scan visually of different CNR?
cheers Bruce On Fri, 24 Mar 2017, Brad Matushewski wrote:
We have a study where subjects are scanned one, and a second time 6 months later. I am looking for changes between the two time point and often times there is a large difference in the “number of defect holes prior to fixing” within the same subject.
Can anyone comment on the significance of this? Given the same brain being scanned 6 months later, how / why is there such a difference?
Logo
Brad J. Matushewski, M.Sc., R.Kin., CSEP-CEP.
Laboratory for Brain & Heart Health School of Kinesiology Western University Room 402, Arthur & Sonia Labatt Health Sciences Building London, ON, Canada, N6A 5B9 Tel: (519) 661-2111 x 89066 Fax: (519) 850-2447
Not that I specifically compared.
-----Original Message----- From: freesurfer-bounces@nmr.mgh.harvard.edu [mailto:freesurfer-bounces@nmr.mgh.harvard.edu] On Behalf Of Bruce Fischl Sent: March 24, 2017 11:58 AM To: Freesurfer support list freesurfer@nmr.mgh.harvard.edu Subject: Re: [Freesurfer] Defect Holes different between scans in same subject
Hi Brad
number of defects is probably a pretty unstable measure. You can change the segmentation of a single WM voxel and cause a defect to appear/disappear. You can also have differences in scan quality due to e.g. motion that can change things. Are the scan visually of different CNR?
cheers Bruce On Fri, 24 Mar 2017, Brad Matushewski wrote:
We have a study where subjects are scanned one, and a second time 6 months later. I am looking for changes between the two time point and often times there is a large difference in the “number of defect holes prior to fixing” within the same subject.
Can anyone comment on the significance of this? Given the same brain being scanned 6 months later, how / why is there such a difference?
Logo
Brad J. Matushewski, M.Sc., R.Kin., CSEP-CEP.
Laboratory for Brain & Heart Health School of Kinesiology Western University Room 402, Arthur & Sonia Labatt Health Sciences Building London, ON, Canada, N6A 5B9 Tel: (519) 661-2111 x 89066 Fax: (519) 850-2447
freesurfer@nmr.mgh.harvard.edu
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Brad Matushewski -
Bruce Fischl