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Updated: Jan 21, 2026

MRI Mapping of Cerebrovascular Reactivity via Gas Inhalation Challenges
Published on: December 17, 2014
Cerebral OEF quantification: A comparison study between quantitative susceptibility mapping and dual-gas calibrated
Yuhan Ma1, Hongfu Sun2,3, Junghun Cho4
1McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada.
Purpose:
To compare regional oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen consumption (CMRO2 ) quantified from the microvascular quantitative susceptibility mapping (QSM) using a hypercapnic gas challenge with those measured by the dual-gas calibrated BOLD imaging (DGC-BOLD) in healthy subjects.
Methods:
Ten healthy subjects were scanned using a 3T MR system. The QSM data were acquired with a multi-echo gradient-echo sequence at baseline and hypercapnia. Cerebral blood flow data were acquired using the pseudo-continuous arterial spin labeling technique. Baseline OEF and CMRO2 were calculated using QSM and cerebral blood flow measurements. The DGC-BOLD data were also collected under a hypercapnic and a hyperoxic condition to yield baseline OEF and CMRO2 . The QSM-OEF and CMRO2 maps were compared with DGC-BOLD OEF and CMRO2 maps using region of interest (vascular territories) analysis and Bland-Altman plots.
Results:
Hypercapnia is a robust stimulus for mapping OEF in combination with QSM. Average OEF in 16 vascular territory regions of interest across 10 subjects was 0.40 ± 0.04 by QSM-OEF and 0.38 ± 0.09 by DGC-BOLD. The average CMRO2 was 176 ± 35 and 167 ± 53 μmol O2 /min/100g by QSM-OEF and DGC-BOLD, respectively. A Bland-Altman plot of regional OEF and CMRO2 in regions of interest revealed a statistically significant but small difference (OEF difference = 0.02, CMRO2 difference = 9 μmol O2 /min/100g, p < .05) between the 2 methods for the 10 healthy subjects.
Conclusion:
Hypercapnic challenge-assisted QSM-OEF is a feasible approach to quantify regional brain OEF and CMRO2 . Compared with DGC-BOLD, hypercapnia QSM-OEF results in smaller intersubject variability and requires only 1 gas challenge.
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