Early post-contrast signal changes in CSF spaces and CSF outflow-related regions on 7 Tesla MRI

Abstract Brain fluid exchange can be studied in vivo with post-contrast MRI, but serial semiquantitative 7 T heavily T2-weighted FLAIR data in healthy adults remain limited. In this prospective study, we characterized post-contrast signal kinetics in CSF spaces and CSF outflow-related regions up to four hours after intravenous gadolinium administration. Fifteen healthy volunteers underwent 7 T MRI before and at 30, 90, 180, and 240 min after gadoterate meglumine administration. Signal intensity (SI) was measured manually in predefined dorsal parasagittal/perivenous regions, ventral perineural regions, and CSF spaces on heavily T2-weighted 3D FLAIR. SI ratios were calculated relative to the splenium, and linear mixed models were used to test time-dependent change. A sensitivity analysis used the choroid glomus as alternative reference. All sampled compartments showed significant time-dependent signal change. Dorsal parasagittal/perivenous regions showed rapid SI-ratio increase by 30 min with later decline, Meckel’s cave showed a similar but slower pattern, and the optic nerve sheath peaked later. CSF spaces showed smaller and slower changes. The main temporal patterns in dorsal and ventral regions persisted with glomus normalization, whereas CSF-space changes were attenuated. These findings provide a normative 7 T semiquantitative benchmark and show distinct compartment-specific post-contrast temporal profiles together with inter-individual variability.