Provided herein are methods and apparatuses for determining a level of cellular metabolic activity for a region of interest in order to detect and map on-going gliovascular unit metabolic activity using high-resolution 1H2O MRI. In one example approach, a computer-implemented method includes receiving a first set of DCE-MRI time-course data for a region, wherein a contrast agent is administered prior to imaging, identifying a region of interest from the first set of DCE-MRI time-course data for further analysis, performing shutter-speed pharmacokinetic analysis of the time-course data associated with the region of interest using computer-implemented software to obtain a finite and non-zero mean water molecule capillary lifetime in the region of interest, and indicating a level of cellular metabolic activity in the brain based on the mean water molecule capillary lifetime.