Quantification of regional CMRO2 in human brain using dynamic 17O-MRI at 3T

Hao Song; Johannes Fisher; Ali Caglar Özen; Burak Akin; Stefan Schumann; Michael Bock

doi:10.1016/j.zemedi.2023.07.004

Quantification of regional CMRO₂ in human brain using dynamic ¹⁷O-MRI at 3T

Z Med Phys. 2023 Aug 7:S0939-3889(23)00086-7. doi: 10.1016/j.zemedi.2023.07.004. Online ahead of print.

Authors

Hao Song¹, Johannes Fisher², Ali Caglar Özen², Burak Akin³, Stefan Schumann⁴, Michael Bock²

Affiliations

¹ Division of Medical Physics, Department of Diagnostic and Interventional Radiology, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany. Electronic address: hao.song@uniklinik-freiburg.de.
² Division of Medical Physics, Department of Diagnostic and Interventional Radiology, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
³ Section on Functional Imaging Methods, NIMH, NIH, Bethesda, MD, USA.
⁴ Department of Anesthesiology and Critical Care, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

PMID: 37558527
DOI: 10.1016/j.zemedi.2023.07.004

Abstract

Objective: To investigate the feasibility of cerebral metabolic rate of oxygen consumption (CMRO₂) measurements with MRI at 3 Tesla in different brain regions.

Methods: CMRO₂ represents a key indicator of the physiological state of brain tissue. Dynamic ¹⁷O-MRI with inhalation of isotopically enriched ¹⁷O gas has been used to quantify global CMRO₂ in brain white (WM) and gray matter (GM). However, global CMRO₂ can only reflect the overall oxygen metabolism of the brain and cannot provide enough information on local tissue oxygen metabolism. To investigate the feasibility of determination of regional CMRO₂ at a clinical 3 T MRI system, CMRO₂ values in frontal, parietal and occipital WM and GM were determined in 5 healthy volunteers and compared to evaluate the regional differences of oxygen metabolism in WM and GM. Additionally, regional CMRO₂ values were determined in deep brain structures including thalamus, dorsal striatum, caudate nucleus and insula cortex and in the cerebella, and compared with literature values from ¹⁵O-PET studies.

Results: In cortical GM the determined CMRO₂ values were in good agreement with the literature, whereas values in WM were about 32-48% higher than literature values. Regional analysis revealed a significantly higher CMRO₂ in the occipital GM compared to the frontal and parietal GM. By contrast, no significant difference of CMRO₂ was observed across the WM. In addition, CMRO₂ in deep brain structures was lower compared to literature values and in the cerebella a good hemispheric symmetry of the tissue oxygen metabolism was found.

Conclusion: Dynamic ¹⁷O-MRI enables direct, non-invasive determination of regional CMRO₂ in brain structures in healthy volunteers at 3T.

Keywords: (17)O-MRI; Brain oxygen metabolism; Cerebral metabolic rate of oxygen consumption (CMRO(2)); Non-proton MRI; Regional quantification of CMRO(2).