T1 measurement in CSF: Intrinsic compartmental differences and tracer concentration assessment in the healthy brain

Motivation: T1 mapping facilitates assessment of brain waste clearance by assessing native solutes or detection of endogenous tracers. Goal(s): To provide a method for accurate measurement of T1 in CSF, to investigate variations in intrinsic T1 of CSF and to measure tracer in CSF after intrathecal administration. Approach: A T2-weighted mixed spin-echo/inversion recovery sequence was implemented to measure T1 in CSF. Five healthy subjects were imaged prior to and four times after intrathecal gadobutrol injection. Results: Baseline R1 is lower in the ventricles than in the subarachnoid space. At 72 hours after injection, there is still gadobutrol in the subarachnoid space. Impact: Accurate T1 measurements in CSF facilitate quantitative study of brain clearance as concentration of Gd-based tracers in CSF can be established. Observed compartmental differences in intrinsic T1 of CSF indicate information on solute concentrations can be measured without endogenous tracer.