Hi there,
I know in the past, it was recommended to acquire 2 T1 scans so that they could be averaged for better SNR, etc. in order to improve cortical thickness and surface area measurements. Is this still the recommendation? We have a few extra minutes in our scanning protocol and are debating whether to include a 2nd T1.
Our parameters are: MPRAGE with .8mm^3 voxel size, slice thickness of .8, FA = 8 degrees, TR = 2400ms, TE = 2.72ms, TI = 1060ms.
Best, Alessandra
Are you getting a 0.8mm isotropic T2w or FLAIR? You would probably get better mileage out of a different type of scan that can help exclude dura and blood vessels if you aren’t already getting one. Also what coil are you using? I might prefer a TI=1000ms simply because it spreads the CSF, GM, and WM histogram peaks out a little more evenly, whereas 1060 will have GM and WM closer together than GM and CSF.
Peace,
Matt.
From: <freesurfer-bounces@nmr.mgh.harvard.edumailto:freesurfer-bounces@nmr.mgh.harvard.edu> on behalf of Alessandra Macbeth <alessandramacbeth@gmail.commailto:alessandramacbeth@gmail.com> Reply-To: Freesurfer support list <freesurfer@nmr.mgh.harvard.edumailto:freesurfer@nmr.mgh.harvard.edu> Date: Wednesday, March 7, 2018 at 1:29 PM To: "freesurfer@nmr.mgh.harvard.edumailto:freesurfer@nmr.mgh.harvard.edu" <freesurfer@nmr.mgh.harvard.edumailto:freesurfer@nmr.mgh.harvard.edu> Subject: [Freesurfer] Collecting 2 T1s Best?
Hi there,
I know in the past, it was recommended to acquire 2 T1 scans so that they could be averaged for better SNR, etc. in order to improve cortical thickness and surface area measurements. Is this still the recommendation? We have a few extra minutes in our scanning protocol and are debating whether to include a 2nd T1.
Our parameters are: MPRAGE with .8mm^3 voxel size, slice thickness of .8, FA = 8 degrees, TR = 2400ms, TE = 2.72ms, TI = 1060ms.
Best, Alessandra
-- Alessandra Macbeth, M.A. Doctoral Candidate - Department of Psychology University of California, Riverside
Hi Alessandra
it's really an empirical question. If 1 image has sufficient SNR/CNR, then adding a second doesn't always help (as it induces some blurring due to interpolation). But if your single image is noisy, which it might be at 0.8 iso, then a second will help. You might try it on one or two subjects and see what you think. An alternative, if you are not already getting them, would be a T2-space or FLAIR T2-space, which can help avoid dura and such
cheers Bruce
On Wed, 7 Mar 2018, Alessandra Macbeth wrote:
Hi there, I know in the past, it was recommended to acquire 2 T1 scans so that they could be averaged for better SNR, etc. in order to improve cortical thickness and surface area measurements. Is this still the recommendation? We have a few extra minutes in our scanning protocol and are debating whether to include a 2nd T1.
Our parameters are: MPRAGE with .8mm^3 voxel size, slice thickness of .8, FA = 8 degrees, TR = 2400ms, TE = 2.72ms, TI = 1060ms.
Best, Alessandra
-- Alessandra Macbeth, M.A. Doctoral Candidate - Department of PsychologyUniversity of California, Riverside
freesurfer@nmr.mgh.harvard.edu
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Alessandra Macbeth -
Bruce Fischl -
Glasser, Matthew