Method for Rapid MRI Quantification of Global Cerebral Metabolic Rate of Oxygen

Abstract

A recently reported quantitative magnetic resonance imaging (MRI) method denoted OxFlow has been shown to be able to quantify whole-brain cerebral metabolic rate of oxygen (CMRO2) by simultaneously measuring oxygen saturation ( S v O 2) in the superior sagittal sinus and cerebral blood flow (CBF) in the arteries feeding the brain in 30 seconds, which is adequate for measurement at baseline but not necessarily in response to neuronal activation. Here, we present an accelerated version of the method (referred to as F-OxFlow) that quantifies CMRO2 in 8 seconds scan time under full retention of the parent method's capabilities and compared it with its predecessor at baseline in 10 healthy subjects. Results indicate excellent agreement between both sequences, with mean bias of 2.2% ( P = 0.18, two-tailed t-test), 3.4% ( P = 0.08, two-tailed t-test), and 2.0% ( P = 0.56, two-tailed t-test) for SvO2, CBF, and CMRO2, respectively. F-OxFlow's potential to monitor dynamic changes in SvO2, CBF, and CMRO2 is illustrated in a paradigm of volitional apnea applied to five of the study subjects. The sequence captured an average increase in SvO2, CBF, and CMRO2 of 10.1 ± 2.5%, 43.2 ± 9.2%, and 7.1 ± 2.2%, respectively, in good agreement with literature values. The method may therefore be suited for monitoring alterations in CBF and SvO2 in response to neurovascular stimuli.