University of Washington experts looked at 160 MRI scans taken from a cohort of 9-to-17-year-olds collected in 2018 then compared these to scans to 130 taken post-pandemic in 2021-2022. University of Washington experts looked at 160 MRI scans taken from a cohort of 9-to-17-year-olds collected in 2018 then compared these to scans to 130 taken post-pandemic in 2021-2022.