Low intensity T1 FreeSurfer

Hi everyone,
I have some T1 images that show reduced intensity (or signal loss) in dorsal cortical areas, and those regions are therefore cut off when FreeSurfer is used for cortical segmentation (see example). Does anyone have a suggestion on how to correct for this signal drop-out somehow before running FreeSurfer or if it is possible to change settings in FreeSurfer to make it more sensitive to pick up on these lower signals?
Thanks!

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