Quantification of regional CMRO in human brain using dynamic O-MRI at 3T.

OBJECTIVE

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

METHODS

CMRO represents a key indicator of the physiological state of brain tissue. Dynamic O-MRI with inhalation of isotopically enriched O gas has been used to quantify global CMRO in brain white (WM) and gray matter (GM). However, global CMRO 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 CMRO at a clinical 3 T MRI system, CMRO 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 CMRO 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 O-PET studies.

RESULTS

In cortical GM the determined CMRO 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 CMRO in the occipital GM compared to the frontal and parietal GM. By contrast, no significant difference of CMRO was observed across the WM. In addition, CMRO 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 O-MRI enables direct, non-invasive determination of regional CMRO in brain structures in healthy volunteers at 3T.