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Hey FreeSurfer Support,

Recently I've been seeing some pial extensions into the subcortical region in FreeSurfer 7.3.2 which cause subcortical segmentation errors in the hippocampus. Turning on wm.mgz, I see erroneous bands of 250 voxels that seem to be causing the extension and subsequent segmentation error. I've tried erasing these bands, but they keep returning upon relaunch.

I've also tried treating it like a pial extension into the cerebellum (i.e. editing brain.finalsurfs.manedit.mgz to correct the boundary) and even tried that edit in conjunction with edits on wm.mgz with voxel value 255 for both. Neither method yielded beneficial results. The pial boundary isn't satisfactorily corrected, the hippocampal exclusion remains, and WM hypointensities are introduced.

I'm not sure what else to try at this point. Is there any reason as to why the 250 voxels keep returning on wm.mgz? Is there a better way to try editing this type of error?

Sincerely,

Hunter Smith, MS, BA

Neuroimaging Engineer

Imaging Core Laboratory (Benzinger)

Washington University in St. Louis School of Medicine

4525 Scott Ave., Campus Box 8225

St. Louis, MO 63110

Cell: 502-759-6661

Email: smiththomas@wustl.edu

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