We evaluated cerebral oxygen extraction fraction (OEF) in patients with sickle cell disease (SCD) and controls using two MR techniques: asymmetric spin echo (ASE) and T2-relaxation-under-spin-tagging (TRUST). We hypothesized that both methods would yield similar OEF and that TRUST-derived OEF would be elevated in patients with SCD vs. controls as previously found using ASE-derived OEF. ASE-derived and TRUST-derived OEF using the Lu 2012 calibration model showed a positive correlation (rho=0.823, p<0.001). Conversely, ASE-derived vs. TRUST-derived OEF using the Bush 2021 model showed a negative association (rho=-0.569, p<0.001). The directionality of these associations was heavily dependent on the calibration model used.