Dr. McLaren,
Thank you for the quick reply.
I plan to set the slices and their regressors to 0. Sorry for the confusion.
Thank you,
Robert
________________________________________
From: SPM (Statistical Parametric Mapping) [[log in to unmask]] on behalf of MCLAREN, Donald [[log in to unmask]]
Sent: Monday, May 13, 2013 4:48 PM
To: [log in to unmask]
Subject: Re: [SPM] Removing Noisy Slices
Do you mean slices or did you mean volumes?
If you meant volumes, this will cause issues with the convolution of
the HRF function. The preferred approach is to add 1 regressor for
each volume you want to remove. Each regressor will contain all 0s
except for the volume that is bad. This approach effectively removes
the volume from the analysis. It would be difficult to form the design
matrix and then filter the volumes out due to the number of references
to row numbers and matrix sizes.
If you meant slices, then we'd need more information about what you
are doing by removing them (e.g. shifting the remaining slices or
setting the slice to 0.
Best Regards, Donald McLaren
=================
D.G. McLaren, Ph.D.
Research Fellow, Department of Neurology, Massachusetts General Hospital and
Harvard Medical School
Postdoctoral Research Fellow, GRECC, Bedford VA
Website: http://www.martinos.org/~mclaren
Office: (773) 406-2464
=====================
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 (773)
406-2464 or email.
On Mon, May 13, 2013 at 4:35 PM, Robert Kim <[log in to unmask]> wrote:
> Dear SPM users,
>
> I have a simple MATLAB script that computes motion artifacts and framewise displacement from fMRI image slices (.swm files). I plan to identify noisy slices using my script and remove them along with their corresponding regressors manually from my design matrix before performing SPM GLM analysis. Is this reasonable?
>
> Thanks in advance,
>
> Robert
|