Fig. 3
Ventricular reflux grades 0–4, describing degree of supra-aqueductal tracer enrichment, are associated with other independent measures of CSF tracer transport and CSF flow. For Ventricular Reflux Grades 0 to 4, there were significant differences in tracer enrichment in 3rd ventricle after 6 h (a; n = 79; P < 0.001), and 24 h (b; n = 86; P < 0.001), and differences in tracer enrichment within lateral ventricles after 6 h (c; n = 76; P < 0.001), and 24 h (d; n = 86; P < 0.001). The Ventricular Reflux Grades 0–4 also differentiated pressure-gradient (dP) in cerebral aqueduct (e; n = 83; P < 0.001), and the CSFAq-CCJ-Ratio (f; n = 27; P < 0.001), i.e. a high degree of supra-aqueductal tracer enrichment was related to a higher pressure gradient in the cerebral aqueduct and also a higher proportion of cranial directed CSF flow in CCJ be transported retrograde in the cerebral aqueduct. The Ventricular Reflux Grade also differentiated mean ICP wave amplitude (MWA) serving as surrogate marker of intracranial compliance (g; n = 53; P = 0.001), though the static ICP (mean ICP) was not different between the Ventricular Reflux Grades (h; n = 51; P = 0.349). Hence, higher MWA, indicative of impaired intracranial compliance was associated with higher degree of supra-aqueductal CSF tracer enrichment. Data presented as box plots with 25th and 75th percentiles and ranges. Statistical differences determined by one-way ANOVA with Bonferroni-corrected post hoc tests