[Mristudio-users] checkered artifact

[Mark A. Pinsk]

Hi everyone,

We're seeing an artifact in our DTI images (most visible in the non-DWI images, but they show up everywhere including the calculated FA maps).  I assume this will negatively impact any tracking analyses.   It's a checkered pattern that originates from high intensity regions (i.e. ventricles) and goes in both the frequency and the phase encode directions.  Links to snapshots below.   I was told by one person that they are Fourier truncation artifacts, but I was also told by another person that they are flow artifacts.

Can someone clarify for me (1) what they are, (2) should I be concerned, and (3) how do I avoid them ?

http://dl.dropbox.com/u/3889124/dti_snapshot1.tiff
http://dl.dropbox.com/u/3889124/dti_snapshot2.tiff

Thanks very much!
Mark