Fig. 1

Left) Midsagittal T2-weighted image, flow acquisition planes for (1) cerebral aqueduct and (2) prepontine cistern. Planes were defined perpendicular to CSF flow. Center top) Example of cerebral aqueduct (T2 TruFisp) with the region of interest for the flow quantification outlined in red. Center Bottom) Example of the phase contrast sequence for the cerebral aqueduct during peak caudal CSF flow. Right top) Example of prepontine cistern (T2 TruFisp) with the region of interest for the flow quantification outlined in red and the basilar artery highlighted in yellow. Right bottom) Example of the phase contrast sequence for the prepontine cistern during peak caudal CSF flow