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Quantification of brain oxygen extraction fraction using QSM and a hyperoxic challenge
Author(s) -
Ma Yuhan,
Mazerolle Erin L.,
Cho Junghun,
Sun Hongfu,
Wang Yi,
Pike G. Bruce
Publication year - 2020
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.28390
Subject(s) - hypercapnia , hyperoxia , cerebral blood flow , medicine , nuclear medicine , quantitative susceptibility mapping , nuclear magnetic resonance , anesthesia , magnetic resonance imaging , physics , respiratory system , radiology , lung
Purpose To use hyperoxia in combination with QSM to quantify microvascular oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO 2 ) in healthy subjects and to cross‐validate results with those from hypercapnia QSM‐OEF. Methods Ten healthy subjects were scanned on a 3T MRI scanner. At baseline normoxia and during hyperoxia (PetO 2 = +300 mmHg), QSM data were acquired using a multi‐echo gradient‐echo (GRE) sequence, and cerebral blood flow data were acquired using a pseudocontinuous arterial spin labeling sequence. The OEF and CMRO 2 maps were computed and compared with those from hypercapnia QSM‐OEF, acquired in the same subjects, using correlation and Bland‐Altman analysis in 16 vascular territories. Results Hyperoxia QSM‐OEF produced physiologically reasonable OEF and CMRO 2 values in all subjects (gray‐matter region of interest average OEF = 0.42 ± 0.04, average CMRO 2 = 181 ± 34 μmol O 2 /min/100 g). When compared with hypercapnia QSM‐OEF, Bland‐Altman plots revealed small deviations (mean OEF difference = 0.015, mean CMRO 2 difference = 4.9 μmol O 2 /min/100 g, P < .05). Good and excellent correlations of regional OEF and CMRO 2 were found for the two methods. In addition, hyperoxia had minimal impact on cerebral blood flow (average gray‐matter cerebral blood flow was reduced by 7.5 ± 5.4%). Conclusions Hyperoxia in combination with QSM is a robust approach to measure OEF. Compared with hypercapnia, hyperoxia is more comfortable and has minimal impact on cerebral blood flow.