Fig. 1: Non-invasive MRI of BCSFB function: characterisation and validation.

a Schematic: the technique works by labelling arterial blood water in the brain’s feeding arteries and tuning the MRI acquisition (using TE = 220 ms) to measure only the signal from labelled blood water that has been transported to the CSF. b Above—the normalised traditional ASL signal that probes BBB function (taken from a cortical ROI) and novel BCSFB-ASL signal, as a function of TI (n = 12 biological independent animals examined over 12 independent experiments; error bars represent SEM); below—example ASL images from a single mouse at increasing TI for both techniques. c Normalised BCSFB-ASL signal (TI = 4 s) at the rostral and caudal section of the lateral ventricles. Example histological sections from rostral and caudal slices are shown for an example mouse that was imaged. n = 10; error bars represent SEM. ***p = 0.000000014 from a one-tailed t-test. d ASL signal (% relative to baseline) before and after administration (100 µU/ml, I.P 0.1 ml) of vasopressin or saline solution. Right column: standard ASL signal probing BBB function; left column: BCSFB-ASL signal. n = 4/5 biological independent animals examined over 4/5 independent experiments for vehicle and vasopressin, respectively; error bars represent SEM. e The pseudo-coefficient (D_app) of the standard ASL and control signal (grey box) and the BCSFB-ASL and control signal at three inflow times (TIs). n = 4 biological independent animals examined over four independent experiments; error bars represent SEM. **p = 0.008 from a one-tailed t-test. f Schematic illustrating modulation of arterial blood water labelling efficiency, the experimental strategy used for the data presented in g and h. g Measured normalised BBB (1st column) and BCSFB (2nd column) ASL signal as a function of TI with full (black line) and partial (grey line) labelling efficiency. n = 5 biological independent animals examined over five independent experiments; error bars represent SEM. h The % decrease in labelling efficiency for the BBB (y-axis) and BCSFB (x-axis) ASL signal across the five mice (p = 0.02, Pearson’s correlation analysis, two sided).