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Hi.
Recently, I analyzed patients who have taken 1.5T MRI ; (Because they had to go in MRI room with some metal materials) and normal controls who took 3.0T MRI. And, after recon and preprocessing of each group of patients and controls in freesurfer v6, I've found that many cortices of patients (1.5T MRI) were significantly reduced, compared with normal age-sex matched controls (3.0T MRI). When I searched in order to know if there is difference between 1.5T vs 3.0T MRI and magnetic field can make a huge difference in calculating volumes or thickness of cortices in Freesurfer, I can find only one article by Heinen and his colleague, reporting there is no big difference and different(1.5 vs 3.0T) magnetic field strength cannot make a significant difference. (Plos ONE, 2016)
Furthermore, given that data which is taken in 1.5T MRI is more likely to have more increased volumes or thickness of cerebral cortices than those of 3.0T MRI, I think that reduced cortical volumes which are calculated using 1.5T MRI have more significance than controls of 3.0T MRI...
Is it true that different magnetic strengths of MRI cannot change the result significantly in Freesurfer?
Thank you always!
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Site effects, even from different scanners with comparable sequences, are a big issue is neuroimaging and discussed in many papers. I think you should be very careful with interpretation of results, especially since in your case, the scanners were different between the groups (!) and additionally operating at different T settings.
Tim
On August 6, 2020 at 6:16 AM Haewon Roh rofree1st@gmail.com wrote:
External Email - Use CautionHi.
Recently, I analyzed patients who have taken 1.5T MRI ; (Because they had to go in MRI room with some metal materials) and normal controls who took 3.0T MRI. And, after recon and preprocessing of each group of patients and controls in freesurfer v6, I've found that many cortices of patients (1.5T MRI) were significantly reduced, compared with normal age-sex matched controls (3.0T MRI). When I searched in order to know if there is difference between 1.5T vs 3.0T MRI and magnetic field can make a huge difference in calculating volumes or thickness of cortices in Freesurfer, I can find only one article by Heinen and his colleague, reporting there is no big difference and different(1.5 vs 3.0T) magnetic field strength cannot make a significant difference. (Plos ONE, 2016)
Furthermore, given that data which is taken in 1.5T MRI is more likely to have more increased volumes or thickness of cerebral cortices than those of 3.0T MRI, I think that reduced cortical volumes which are calculated using 1.5T MRI have more significance than controls of 3.0T MRI...
Is it true that different magnetic strengths of MRI cannot change the result significantly in Freesurfer?
Thank you always!
-- Hae Won ROH, M.D.
H.P: +82-10-4341-8142 E-mail: rofree1st@gmail.com _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
-- Dr. Tim Schäfer Postdoc Computational Neuroimaging Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy University Hospital Frankfurt, Goethe University Frankfurt am Main, Germany
Hi Haewon
The problem is that you will never be able to distinguish a scanner effect from a real biological effect since they are in the same subspace. At the very least you should find some control data on both scanners to show that there is no bias in the direction of the effect you are finding.
Cheers Bruce
From: freesurfer-bounces@nmr.mgh.harvard.edu freesurfer-bounces@nmr.mgh.harvard.edu On Behalf Of Haewon Roh Sent: Thursday, August 6, 2020 12:16 AM To: freesurfer@nmr.mgh.harvard.edu Subject: [Freesurfer] Needing advises for results in my study.
External Email - Use Caution Hi.
Recently, I analyzed patients who have taken 1.5T MRI ; (Because they had to go in MRI room with some metal materials) and normal controls who took 3.0T MRI. And, after recon and preprocessing of each group of patients and controls in freesurfer v6, I've found that many cortices of patients (1.5T MRI) were significantly reduced, compared with normal age-sex matched controls (3.0T MRI). When I searched in order to know if there is difference between 1.5T vs 3.0T MRI and magnetic field can make a huge difference in calculating volumes or thickness of cortices in Freesurfer, I can find only one article by Heinen and his colleague, reporting there is no big difference and different(1.5 vs 3.0T) magnetic field strength cannot make a significant difference. (Plos ONE, 2016)
Furthermore, given that data which is taken in 1.5T MRI is more likely to have more increased volumes or thickness of cerebral cortices than those of 3.0T MRI, I think that reduced cortical volumes which are calculated using 1.5T MRI have more significance than controls of 3.0T MRI...
Is it true that different magnetic strengths of MRI cannot change the result significantly in Freesurfer?
Thank you always!
-- Hae Won ROH, M.D.
H.P: +82-10-4341-8142 E-mail: rofree1st@gmail.commailto:rofree1st@gmail.com
freesurfer@nmr.mgh.harvard.edu
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Fischl, Bruce -
Haewon Roh -
Tim Schäfer