Hello,
I thought I'd ask the collective wisdom and experience of the SPM list if they've ever seen out of brain clusters like those in the attached image.
These are first-level individual subject SPMs at a FDR 0.05 10 voxel threshold. A number of subjects are showing highly significant clusters way outside the skull. Some are in the bone, but many are multiple mm away from any tissues, and I wonder what might be causing them? Could residual motion in anyway be responsible? I can't think of any design or preprocessing mistake I could have made that would or even could create these, but I am open to any suggestions!
I'm concerned it is some kind of scanner noise, and it seems to be appearing more frequently in my recent scans, and need to decide if we should suspend scanning.
Thanks,
Graeme
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Graeme C. Schwindt, HBSc
MD/PhD Student
University of Toronto
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