A few scans failed initial QC due to small amounts of dura classified as brain at the top of the head that required editing and were mistakenly excluded. These scans are now included and do not change the results (in particular, \(CV_a\), as this is the most important for power calculations). We have included the results from the revised dataset in the manuscript. For the new QC procedure, eTIV was checked as suggested by the reviewer; this QC check is advantageous because it is the first step of recon-all and is sensitive to misregistration to the talairach template that could lead to inaccurate segmentations overall. Finally only 3 scans were rejected due to failing QC at the registration step, which were from the same subject at sites 4 and 6 and second subject at site 11. Three other scans were not included due to acquisition/ data transfer issues: One scan was not acquired due to time constraints, one scan was left out because part of the head was not acquired (possibly the files were corrupted), and one scan was erroneously deleted at the site. A column has been added in the acquisition tables to reflect how many actual scans were acquired at each site.