Cerebral metabolic rate of oxygen (CMRO2) quantifies the amount of oxygen consumed by the brain, and relies on continuous delivery of nutrients and oxygen via cerebral blood flow (CBF). In sickle cell disease (SCD), CBF is elevated to compensate for chronic anaemia. This study investigates CMRO2 in adults with SCD using T2-prepared tissue relaxation with inversion recovery (T2-TRIR). CBF increased after acetazolamide-induced vasodilation in both groups but CMRO2 reduced even further in SCD patients while it remained stable in controls. Our results suggest that cerebral shunting is exacerbated by high flow conditions.