Yea, not sure. It could be that the uptake in WM near the NAcc is
somewhat less than average (GTM assumes constant throughout). If so,
then the GTM would subtract too much from the NAcc in an attempt to
remove the spill in from WM. This is more of a problem for amyoild and
tau ligands because
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Thanks Doug. we double checked the registration with gtm.seg.mgz and it
looks good. Also the uptake in Acc is not much smaller than other regions
and is pretty similar on both hemispheres so we are not sure what could be
causing this. Any suggestions
It may or may not be something that needs to be fixed. The PVC is just a linear
model where the regression coefficients are the uptake in each ROI. As with any
model, it adjusts the regression coefs to minimize the error in the fit. If
some end up being less than zero when you really expect all
