PurposeTo quantitatively map cerebral metabolic rate of oxygen ( ) and oxygen extraction fraction ( ) in human brains using quantitative susceptibility mapping (QSM) and arterial spin labeling‐measured cerebral blood flow (CBF) before and after caffeine vasoconstriction.MethodsUsing the multiecho, three‐dimensional gradient echo sequence and an oral bolus of 200 mg caffeine, whole brain and were mapped at 3‐mm isotropic resolution on 13 healthy subjects. The QSM‐based was compared with an ‐based to analyze the regional consistency within cortical gray matter (CGM) with the scaling in the method set to provide same total as the QSM method for each subject.ResultsCompared to precaffeine, susceptibility increased (5.1 ± 1.1 ppb; P < 0.01) and decreased (−23.6 ± 6.7 ml/100 g/min; P < 0.01) at 25‐min postcaffeine in CGM. This corresponded to a of 153.0 ± 26.4 μmol/100 g/min with an of 33.9 ± 9.6% and 54.5 ± 13.2% (P < 0.01) pre‐ and postcaffeine, respectively, at CGM, and a of 58.0 ± 26.6 μmol/100 g/min at white matter. from both QSM‐ and ‐based methods showed good regional consistency (P > 0.05), but quantitation of ‐based required an additional scaling factor.ConclusionQSM can be used with perfusion measurements pre‐ and postcaffeine vascoconstriction to map and OEF. Magn Reson Med 74:945–952, 2015. © 2014 Wiley Periodicals, Inc.