[Eeglablist] fMRI artifact removal

Marcel Bastiaansen Marcel.Bastiaansen at fcdonders.ru.nl
Wed Sep 28 01:57:55 PDT 2005


Dear Yuko,

I have no experience with the fMRIb tool, but:

It is my experience that everything below 1 KHz is way too low to 
adequately sample the gradient artefacts produced by the EPI sequence.
This will result in a shape of the gradient artefact that varies from 
volume to volume. This makes it impossible to compute anaverage gradient 
artefact for the subtraction.

You should sample at 5 KHz or higher to get rid of this problem.

Kindly,
Marcel Bastiaansen

Yuko Yotsumoto wrote:

> Hi all,
>
> I have EEG data recorded in the fMRI scanner.
> Our EEGs were recorded with 957 Hz, while fMRI was operating at 4TR 
> with 35 slices. Recording time was about 160 sec. Trigger signals were 
> obtained at every image acquisition (=35 triggers for 4 TR).
>
> I'm trying to remove EPI noise artifacts with fMRIb plug-in, but have 
> been unable to get clean results.
>
> With fMRIb plug-in, I used parameter sets such as follows.
>
> Low-pass filter cut off : 30
> Interpolation folds : 21
> Artifact-timing event : slice
> ANC : on
> Correct for missing triggers : off
> Relative trigger location : 0
> # of residuals PC to remove : auto
>
> I am wondering if our sampling rate of 957 Hz might not be high enough 
> to use fMRIb plug-in. Have anybody in this mailing list tried this 
> plug in with a similar sampling rate? Did it work?
>
> Thanks!
>
> Yuko
>
>
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-- 
dr. Marcel C.M. Bastiaansen.
FC Donders Centre for Cognitive Neuroimaging
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