[Eeglablist] fMRI artifact removal

Yuko Yotsumoto yuko at nmr.mgh.harvard.edu
Wed Sep 28 11:53:36 PDT 2005


Hi Marcel,

According to their publication and web page, fMRIb plug-in works with as 
low as 2048 Hz sampling rate, which I think makes this plug-in very 
valuable.

But 957 Hz is probably too low... I am wondering if anybody knows the 
minimum requirement for sampling rate to apply fMRIb.

Thanks,
Yuko

Marcel Bastiaansen wrote:

> 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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