Quantification of CSF T1 and T2 in the Subarachnoid Space: Implication for Brain-CSF Exchange

It has been suggested that the brain’s waste clearance system involves water exchange between brain tissue and CSF in perivascular spaces, which are part of the subarachnoid space (SAS). In this work, we found CSF T1 and T2 in SAS were shorter than corresponding values in the frontal-horns of lateral ventricle, which have minimal exchange. Numerical simulations showed that a higher brain-CSF water exchange rate was associated with lower apparent relaxation time in SAS, providing a potential means to estimate brain-CSF water exchange rate in vivo.