FIG 5. Aqueductal stenosis without spontaneous ventriculostomy in patient with active obstructive hydrocephalus that required ventricular shunting.

A. Sagittal midline T1-weighted image (SE 450/15/2) reveals severe ventricular dilatation with distal narrowing of aqueduct.

B. Sagittal midline phase-contrast MR imaging (2D-FISP 70/13/15°). Images represent a point in midsystole (left) and middiastole (right). Craniocaudal pulsatile flow is not seen through aqueduct. Note asynchronic CSF flow between anteroinferior part of third ventricle (arrow) and prepontine subarachnoid spaces (arrowhead).