 |
 |
I've noticed that after the realignment of different sessions
there's only one meanEPI file created with different rp.txt files for each
session. So I assume this mean EPI is the mean of all sessions (which I will
be using for coregistration), but the txt files will be put in later model
specification for each session? Thank you all for the valuable help.
Wei
From: SPM (Statistical
Parametric Mapping) [mailto:[log in to unmask]] On Behalf Of MCLAREN,
Donald
Sent: Thursday, December 10, 2009 11:44 AM
To: [log in to unmask]
Subject: Re: [SPM] realignment of different sessions
They should be treated separately, but aligned to the same
target time point. To do this, enter each scan as a different session under
Realign --> Data. You will have 2 sessions under data. Now all the data are
aligned and you can do the same procedures to all the time points in the
following steps. Just remember to have 2 sessions for each step.
Best Regards, Donald McLaren
=================
D.G. McLaren
University of Wisconsin - Madison
Neuroscience Training Program
Office: (608) 520-0586
=====================
This e-mail contains CONFIDENTIAL INFORMATION which may contain PROTECTED
HEALTHCARE INFORMATION and may also be LEGALLY PRIVILEGED and which is intended
only for the use of the individual or entity named above. If the reader of the
e-mail is not the intended recipient or the employee or agent responsible for
delivering it to the intended recipient, you are hereby notified that you are
in possession of confidential and privileged information. Any unauthorized use,
disclosure, copying or the taking of any action in reliance on the contents of
this information is strictly prohibited and may be unlawful. If you have received
this e-mail unintentionally, please immediately notify the sender via telephone
at (608) 520-0586 or email.
On Thu, Dec 10, 2009 at 10:37 AM, Julie McEntee <[log in to unmask]> wrote:
You
have to treat each scan separately; scans cannot be concatenated.
You should realign each session independently (the spikes you see between
sessions reflect movement of the subject between scans- when a scan isn’t being
ran, which frequently occurs). You should only be concerned about within-scan
motion; if the most you have is 0.2 mm, that’s great (I would say the generally
accepted amount within scans is below 2 mm; others may comment on this).
You would then model each session independently and use the con files in a
second-level analysis (which type depends on your research question).
-Julie
Julie E. McEntee, MA, CCRP
Senior Research Program Coordinator
Department of Psychiatry- Neuroimaging
Johns Hopkins University School of Medicine
600 N. Wolfe St./Phipps 300
Baltimore, MD 21287
Phone: 410-502-0468
Fax: 410-614-3676
On 12/10/09 11:21 AM, "Huang, Wei (Psychiatry)" <[log in to unmask]" target="_blank">[log in to unmask]>
wrote:
Dear All,
I'm a beginner and am trying to figure out the following: I have multiple EPI sessions from the same subject on the same day. I'm trying to include these EPIs in the realignment step. The result gave me a below 0.2mm translation within scans but there's at least 2mm spikes between sessions. Is this 2mm very bad? Would my later result still be reliable based on this first step? My EPI pixel size is 1.8x1.8x4mm.
Thanks in advance for your help.
Wei