Print

Print
Hi Dear Steve,

I was trying to add a confound EV. I use 3 columns files, and use cat -v check, no hidden character; use wc check, the lines of confound EV  equal to the sum of the 8 original EV lines. (I have 7 task EVs and the 8th EV for scanner spikes). In the confound EV text file, all the spikes are set to 1 in 3rd column and other tasks are to 0 respectively. But the full model setting always prompt 'terminate called after throwing an instance of NEWMAT: Incompatible Dimension Exception'. Is there any mistake on my EV setting? I'll appreciate it if you have time to give a look at my timing files attached. The timing is from log file of Presentation(NBS).

Thanks,
Emma

On Wed, Jun 10, 2009 at 3:23 PM, Steve Smith <[log in to unmask]> wrote:
Hi - it depends how the artefact is interacting with the signal of interest.  If it's very strong then if may be best to ignore that timepoint completely, in which case you could add an extra regressor into FEAT that is zero at all timepoints except when the spike occurs.

Cheers.




On 9 Jun 2009, at 16:02, Emma Liang wrote:

Dear Dr Smith,

Thanks a lot. The ICA paper is very helpful. But I am a very beginer on signal processing methods, still need time to digest it. My current comprehension is that each MELODIC component is a part  of  original signal throughout the whole time serial. In my data, the scanner 'spike' noises affected each component and made the real activation signal very insignificant. I want to filter the EPI imaging by cutting all the intensity over 1000(machine spikes at over 2000) to 1000 and make them as a task. Is it ok? and is there a function to do that? Sorry if the question is too silly.

Cheers,
Emma

On Fri, Jun 5, 2009 at 4:07 PM, Steve Smith <[log in to unmask]> wrote:
Hi, see the FAQ:

http://www.fmrib.ox.ac.uk/fslfaq/#melodic_filter

Cheers.



On 3 Jun 2009, at 12:42, Emma Liang wrote:

Dear FSLers,

I have a EPI imaging with some white noise slices throughout(about 20 of 500 volumes contaminated)  because a unknown scanner fault. Is there any method to get rid of them or ignore? I'm going to make all the volumes with noise  as  a separated  task,  is it feasible?  Thanks!

Cheers,
Emma


---------------------------------------------------------------------------
Stephen M. Smith, Professor of Biomedical Engineering
Associate Director,  Oxford University FMRIB Centre

FMRIB, JR Hospital, Headington, Oxford  OX3 9DU, UK
+44 (0) 1865 222726  (fax 222717)
[log in to unmask]    http://www.fmrib.ox.ac.uk/~steve
---------------------------------------------------------------------------



---------------------------------------------------------------------------
Stephen M. Smith, Professor of Biomedical Engineering
Associate Director,  Oxford University FMRIB Centre

FMRIB, JR Hospital, Headington, Oxford  OX3 9DU, UK
+44 (0) 1865 222726  (fax 222717)
[log in to unmask]    http://www.fmrib.ox.ac.uk/~steve
---------------------------------------------------------------------------