List,
I am trying to determine exactly what the difference is between an
"adjusted" VOI value is, and one where no adjustment has taken place.
See this gif for a graphical description:
http://neuropet-bri.org/spm/spm01.gif
I am looking for linear changes in perfusion with treatment over seven
scans, as compared to a group of untreated controls. After I produce the
Z-map, I placed a 5mm VOI over a blob. The two graphs at bottom represent
adjusted and nonadjusted responses, respectively.
I guess my questions are:
1. How do I get the mean voxel value from the VOI after the image has been
globally scaled? Is this what "no adjustment" means?
2. Why do neither of these graphs (see link below) of the patient VOI values
compared to the mean of the control VOI values bear any resemblance to the
contrast that I am using? In other words, this does not look like linear
changes to me, despite the fact that it was produced by the contrast shown.
Can anyone explain this, please?
Thanks,
James Patterson
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|