Dynamic oxygen-17 MRI with adaptive temporal resolution using golden-means-based 3D radial sampling

Purpose: The aim of this study was to develop a high-resolution 3D oxygen-17 (¹⁷ O) MRI method to delineate the kinetics of ¹⁷ O-enriched water (H₂¹⁷ O) across the entire mouse brain after a bolus injection via the tail vein.

Methods: The dynamic ¹⁷ O signal was acquired with a golden-means-based 3D radial sampling scheme. To achieve adequate temporal resolution with preserved spatial resolution, a k-space-weighted view sharing strategy was used in image reconstruction with an adaptive window size tailored to the kinetics of the ¹⁷ O signal. Simulation studies were performed to determine the adequate image reconstruction parameters. The established method was applied to delineating the kinetics of intravenously injected H₂¹⁷ O in vivo in the post-stroke mouse brain.

Results: The proposed dynamic ¹⁷ O-MRI method achieved an isotropic resolution of 1.21 mm (0.77 mm nominal) in mouse brain at 9.4T, with the temporal resolution increased gradually from 3 s at the initial phase of rapid signal increase to 15 s at the steady-state. The high spatial resolution enabled the delineation of the heterogeneous H₂¹⁷ O uptake and washout kinetics in stroke-affected mouse brain.

Conclusion: The current study demonstrated a 3D ¹⁷ O-MRI method for dynamic monitoring of ¹⁷ O signal changes with high spatial and temporal resolution. The method can be utilized to quantify physiological parameters such as cerebral blood flow and blood-brain barrier permeability by tracking injected H₂¹⁷ O. It can also be used to measure oxygen consumption rate in ¹⁷ O-oxygen inhalation studies.