AFNI Message Board

Dear AFNI users-

We are very pleased to announce that the new AFNI Message Board framework is up! Please join us at:

https://discuss.afni.nimh.nih.gov

Existing user accounts have been migrated, so returning users can login by requesting a password reset. New users can create accounts, as well, through a standard account creation process. Please note that these setup emails might initially go to spam folders (esp. for NIH users!), so please check those locations in the beginning.

The current Message Board discussion threads have been migrated to the new framework. The current Message Board will remain visible, but read-only, for a little while.

Sincerely, AFNI HQ

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Jatin Vaidya
November 26, 2008 01:30PM
Hi,

I recently noticed some ringing artifact on our fMRI images. It appears that this happens after volume registration using 3dvolreg (which we run after despiking and time shifting the data). We thought it was related to using the Fourier option in volreg but the ringing artifact is evident even when using cubic interpolation. This pattern is evident on all our images and I did not notice earlier because it only becomes apparent in the AFNI window when setting the image in question as an overlay (due to the way the values are auto scaled and color coded). Although you can't really tell on the images attached, the values outside of the brain gradually become smaller (e.g., a value of four closest to the brain and a value of 1 further away).

I'm curious if others see a similar pattern and if it is something to worry about if this ringing also evident inside the brain.

Thanks,

Jatin
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Subject Author Posted

ringing artifact

Jatin Vaidya November 26, 2008 01:30PM

Re: ringing artifact

bob cox November 27, 2008 11:54AM

Re: ringing artifact

Jatin December 01, 2008 11:55AM