Hi Sandra,
are you referring to (structural) MRI or fMRI? I do not have much experience with structural MRI, but generally speaking I do not think it makes much sense to compare data from different sequences to say anything different than about the sequence itself. But perhaps others with more experience in longitudinal MRI can advise on that.
When you really must, I would stick with the old inferior sequence. Adding noise to your data is IMHO less of an issue than inducing a big confounding factor, At least when you find something you can be more certain that it is valid. When you only compare findings qualitatively you might get away with it.
Or start over with the new sequence and wait another 2 years ;-)
But as said, my remarks are rather general, others might know more. I'd add more detail in your description of the problem (what is your measurment, what are you going to analyse and how) in a follow up post.
Good luck,
Bas
--------------------------------------------------
Dr. S.F.W. Neggers
Division of Brain Research
Rudolf Magnus Institute for Neuroscience
Utrecht University Medical Center
Visiting : Heidelberglaan 100, 3584 CX Utrecht
Room B.01.1.03
Mail : Huispost B01.206, P.O. Box 85500
3508 GA Utrecht, the Netherlands
Tel : +31 (0)88 7559609
Fax : +31 (0)88 7555443
E-mail : [log in to unmask]
Web : http://www.neuromri.nl/people/bas-neggers
: http://www.brainsciencetools.com (CEO)
--------------------------------------------------
________________________________________
From: Sandra Chanraud [[log in to unmask]]
Sent: Friday, July 20, 2012 1:06 PM
To: Neggers, S.F.W.
Cc: [log in to unmask]
Subject: Re: [SPM] Longitudinal resting state study
Hi Bas,
Thanks a lot for your response.
Unfortunately, the sequence we used at first is poor.
What about scanning 10 subjects with the previous and the new sequences (during activation and rest conditions) and checking for differences?
Best,
Sandra.
Le Vendredi 20 Juillet 2012 12:54 CEST, "Neggers, S.F.W." <[log in to unmask]> a écrit:
> Hi Sandra,
>
> this of course will highly depend on the differences in your sequence, hard to tell otherwise. But why dont you simply use the same sequence in the first place? That would be optimal. Mostly, results from different sequences are hard to compare quantitatively, especially for fMRI, IMHO.
>
> Good luck,
>
> Bas
>
>
> --------------------------------------------------
> Dr. S.F.W. Neggers
> Division of Brain Research
> Rudolf Magnus Institute for Neuroscience
> Utrecht University Medical Center
>
> Visiting : Heidelberglaan 100, 3584 CX Utrecht
> Room B.01.1.03
> Mail : Huispost B01.206, P.O. Box 85500
> 3508 GA Utrecht, the Netherlands
> Tel : +31 (0)88 7559609
> Fax : +31 (0)88 7555443
> E-mail : [log in to unmask]
> Web : http://www.neuromri.nl/people/bas-neggers
> : http://www.brainsciencetools.com (CEO)
> --------------------------------------------------
>
> ________________________________________
> From: SPM (Statistical Parametric Mapping) [[log in to unmask]] on behalf of Sandra Chanraud [[log in to unmask]]
> Sent: Friday, July 20, 2012 12:20 PM
> To: [log in to unmask]
> Subject: [SPM] Longitudinal resting state study
>
> Dear all,
>
> We are planning to scan people who already had a MRI protocol about 2 years ago. The functional sequence that we will be using is different from the previous one, so that we wonder about the validity of comparing data from the 2 different scans.
>
> Any advise?
>
> Thanks in advance.
>
> Best,
> Sandra.
>
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