Three-dimensional T1 measurement in the cerebrospinal fluid using the SPACE-FLAIR sequence

Motivation: The longitudinal relaxation time (T1) of cerebrospinal fluid (CSF) informs on tissue-CSF water exchange, but current protocols are two-dimensional and low-resolution. Goal(s): To develop a high-resolution three-dimensional (3D) protocol for measuring T1 of CSF in the whole brain. Approach: The 3D-SPACE-FLAIR sequence was optimised with high isotropic resolution, two long inversion times, and an ultralong echo time, delivering two images for inversion-recovery-based T1 mapping of CSF. Results: Whole-brain high-resolution T1 maps of CSF were obtained in five healthy subjects. T1 values across the brain were within the expected range. Regional values of T1 demonstrated shortening in areas with greater tissue-CSF water exchange. Impact: We propose a high-resolution 3D protocol for investigating relative differences in T1 across the cerebral CSF due to tissue-CSF water exchange. This methodology may help characterise processes of waste removal from the brain to which CSF is thought to contribute.