Fig. 2

Up to 33% and on average 25% of the intrathecally injected tracer spreads into the brain over a time frame of 24–48 h. A T1-weighted MRI at baseline and overlay with tracer concentrations (mmol/L) after \(\sim \)6, 24, and 48 h in a sample subject; B–D: total amount of tracer (mmol) in the brain (B), cerebral cortex (C) or subcortical white matter (D) over time for all subjects combined. Error bars represent standard deviation