Michael,
In general, spatial smoothing should not be done when an ROI analysis is
subsequently intended. This is because spatial smoothing introduces a
partial volume error into the ROI signal.
Eric
>
> Furthermore, if you are doing a ROI analysis (extracting the mean
> perfusion in a large ROI like the vascular region of the posterior
> cerebral artery) instead of a voxel-based analysis (no random field
> theory!), is it necessary to smooth the image? If so, what would be a
> criterion for the size of the smoothing kernel, e.g. for a acquired
> voxel size of [2 2 8], normalized to a voxel size of [2 2 2]?
>
> Thanks in advance,
> Michael Hermes
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