Choroid plexus tissue perfusion and secretory function in rats measured by non-invasive MRI reveal significant effects of anesthesia

The choroid plexus (ChP) of the cerebral ventricles is a source of cerebrospinal fluid (CSF) production and also plays a key role in immune surveillance at the level of blood-to-CSF-barrier (BCSFB). In this study, we quantify ChP blood perfusion and BCSFB mediated water exchange from arterial blood into ventricular CSF using non-invasive continuous arterial spin labelling magnetic resonance imaging (CASL-MRI). Systemic administration of anti-diuretic hormone (vasopressin) was used to validate BCSFB mediated water exchange as a metric of choroidal CSF secretory function. To further investigate the coupling between ChP perfusion and CSF secretory function, we characterized the effects of two anesthetic regimens known to have large-scale differential effects on cerebral blood flow. For quantification of ChP blood perfusion a multi-compartment perfusion model was employed, and we discovered that partial volume correction improved measurement accuracy. Vasopressin significantly reduced both ChP blood perfusion and CSF secretory function. ChP perfusion was significantly higher with pure isoflurane anesthesia (2-2.5%) when compared to a balanced anesthesia with dexmedetomidine and low-dose isoflurane (1.0 %), however there was no significant difference in BCSFB water secretory function. In summary, here we introduce a non-invasive, robust, and spatially resolved in vivo imaging platform to quantify ChP perfusion as well as BCSFB water secretory function which can be applied to study coupling of these two key parameters in future clinical translational studies.