Non-invasive MRI of choroid plexus vascular function.

Choroid plexus (ChP) is a highly vascularized tissue in the ventricles of the brain, and it plays an important role in the production of cerebrospinal fluid (CSF) and formation of the blood-CSF barrier. The function of ChP vessels has been implicated in waste clearance efficiency during aging and neurodegenerative diseases. At present, postmortem studies are the main method to assess choroid plexus vascular integrity, with a few tools to measure ChP function in living humans. Here, we proposed a non-invasive MRI approach to assess ChP vascular elasticity based on the detection of MRI signal changes in response to vasoactive challenges. The mechanism of the signal is hypothesized to be due to reciprocal blood and stroma volume alterations during vessel expansion. We demonstrated that ChP vascular elasticity can be evaluated with BOLD MRI using a hypercapnia challenge of CO2 inhalation. This effect is specifically located in the brain ventricles where ChP is abundant. We revealed the ability of the technique in detecting age-related reduction in ChP vascular elasticity. We further showed that this effect can be assessed with gas-free methods, including intermittent breath modulation and resting-state BOLD fMRI. We characterized the image contrast requirement under which this effect can be detected. This technique may provide a clinically feasible tool for assessing ChP vascular function in health and disease.