Whole-brain and segmented CBF and OEF between cohorts. Although there was no difference in CBF among the 3 cohorts in the whole brain, gray matter, or white matter (A), there was a significant decrease in whole brain, gray matter and white matter OEF in the cohort receiving HU therapy (blue) compared with those not receiving disease-modifying therapy (red), but not to the extent of those receiving CTT (green) (B). *Statistically significant after Benjamini-Hochberg step-up procedure used to correct for multiple comparisons.