Fig. 3

Distribution of the Gd-tracer over time in each representative region for CSF space and drainage pathways. In the forebrain section (b), signal ratio maps of the KO and WT groups and subtraction images (generated by subtracting the signal ratio maps of the WT group from those of the KO group and converting them into color maps) are shown. Each signal ratio map represents the average data for the five rats in each group. In the subtraction images, violet indicates a lower tracer distribution in the KO group than that in the WT group, whereas orange indicates the opposite. Each subtraction image is shown in sections of the nasal cavity, dural lymphatics, and dorsal and ventral CSF spaces (c). Cross-sectional references are indicated by orange dashed lines (a). In the KO group, Gd-tracer distribution along the optic nerve sheath (arrows in B), upper nasal turbinate (dashed circles in c), and dural lymphatics (arrows in c) was reduced compared to that in the WT group. In contrast, the Gd-tracer distribution in the CSF space of the KO group was higher than that of the WT group (dotted rectangles in b and c, respectively). CSF, cerebrospinal fluid; DL, dural lymphatics; Gd, gadolinium-based contrast agents; KO, aquaporin 4 knockout; OPT, optic nerve sheath; UNT, upper nasal turbinate; WT, wild type.