Also, correlations so specific to the ventricles can be enhanced by breathing and heart pulsations, which is probably why Peter asked about your acquisition parameters (e.g. TR or multi-band options). But it also seems possible that you are choosing a seed location that hits or is in a ventricle (the question on registration may be alluding to that). Exactly how are you choosing and applying a seed? Especially if it is just a single coordinate or a "sphere", have you looked to see where it is on each subject?
- rick
