Reproducibility of CMRO determination using dynamic O MRI.

PURPOSE

To assess the reproducibility of O MRI-based determination of the cerebral metabolic rate of oxygen consumption (CMRO ) in healthy volunteers. To assess the influence of image acquisition and reconstruction parameters on dynamic quantification of functional parameters such as CMRO .

METHODS

Dynamic O MRI data were simulated and used to investigate influences of temporal resolution (Δt) and partial volume correction (PVC) on the determination of CMRO . Three healthy volunteers were examined in two separate examinations. In vivo O MRI measurements were conducted with a nominal spatial resolution of (7.5 mm) using a density-adapted radial sequence with golden angle acquisition scheme. In each measurement, 4.0 ± 0.1 L of 70%-enriched O gas were administered using a rebreathing system. Data were corrected with a PVC algorithm, and CMRO was determined in gray matter (GM) and white matter (WM) compartments using a three-phase metabolic model (baseline, O inhalation, decay phase).

RESULTS

Comparison with the ground truth of simulations revealed improved CMRO determination after application of PVC and with Δt ≤ 2:00 min. Evaluation of in vivo data yields to CMRO  = 2.31 ± 0.1 μmol/g/min and to CMRO  = 0.69 ± 0.04 μmol/g/min with coefficients of variation (CoV) of 0.3-5.5% and 4.3-5.0% for intra-volunteer and inter-volunteer data, respectively.

CONCLUSION

This in vivo O inhalation study demonstrated that the proposed experimental setup enables reproducible determination of CMRO in healthy volunteers. Magn Reson Med 79:2923-2934, 2018. © 2017 International Society for Magnetic Resonance in Medicine.