| Autor: |
Deckers PT; Department of Neurosurgery, University Medical Center Utrecht, Utrecht, Netherlands., Bhogal AA; Department of Radiology, Center for Image Sciences, University Medical Center Utrecht, Utrecht, Netherlands., Dijsselhof MB; Department of Radiology, Center for Image Sciences, University Medical Center Utrecht, Utrecht, Netherlands.; Department of Radiology and Nuclear Medicine, Amsterdam Neuroscience, Amsterdam UMC (location VUmc), Amsterdam, Netherlands., Faraco CC; Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA., Liu P; Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA., Lu H; Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA., Donahue MJ; Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA., Siero JC; Department of Radiology, Center for Image Sciences, University Medical Center Utrecht, Utrecht, Netherlands.; Spinoza Centre for Neuroimaging, Amsterdam, Netherlands. |
| Abstrakt: |
Blood oxygenation level-dependent (BOLD) or arterial spin labeling (ASL) MRI with hypercapnic stimuli allow for measuring cerebrovascular reactivity (CVR). Hypercapnic stimuli are also employed in calibrated BOLD functional MRI for quantifying neuronally-evoked changes in cerebral oxygen metabolism (CMRO 2 ). It is often assumed that hypercapnic stimuli (with or without hyperoxia) are iso-metabolic; increasing arterial CO 2 or O 2 does not affect CMRO 2 . We evaluated the null hypothesis that two common hypercapnic stimuli, 'CO 2 in air' and carbogen, are iso-metabolic. TRUST and ASL MRI were used to measure the cerebral venous oxygenation and cerebral blood flow (CBF), from which the oxygen extraction fraction (OEF) and CMRO 2 were calculated for room-air, 'CO 2 in air' and carbogen. As expected, CBF significantly increased (9.9% ± 9.3% and 12.1% ± 8.8% for 'CO 2 in air' and carbogen, respectively). CMRO 2 decreased for 'CO 2 in air' (-13.4% ± 13.0%, p < 0.01) compared to room-air, while the CMRO 2 during carbogen did not significantly change. Our findings indicate that 'CO 2 in air' is not iso-metabolic, while carbogen appears to elicit a mixed effect; the CMRO 2 reduction during hypercapnia is mitigated when including hyperoxia. These findings can be important for interpreting measurements using hypercapnic or hypercapnic-hyperoxic (carbogen) stimuli. |
