Contrast-enhanced studies also show that focal thickening takes place at the exit of the nerve in the interpeduncular cistern
without enhancement of the cavernous sinus or adjacent dura.
On MR angiography, the internal cerebral vein and the vein of Galen were observed to be dilated and an arteriovenous malformation (AVM) was noted originating from the interpeduncular cistern
extending into the quadrigeminal cistern and lateral ventricle, nourished by the posterior cerebral artery, draining into the internal cerebral vein and vein of Galen.
The normal relationship between these supra- and infratentorial structures and their measurements including the mammillary-pontine distance, height of the interpeduncular cistern
at the plane of the cecum, and the ratio of these measurements are illustrated in Figure 1.
Dysgenesis of the pontomesencephalic isthmus results in the molar tooth appearance with widening of the interpeduncular cistern
and abnormal thickening of the elevated superior cerebellar peduncles.
Magnetic resonance imaging (MRI) of the brain with contrast showed a well-enhanced mass in the suprasellar region, extending posteriorly into interpeduncular cistern
and compressing the posterior cerebral arteries.
Because patients are usually scanned in the supine position, particularly important locations include the interpeduncular cistern
, the occipital horns of the lateral ventricles, the quadrigeminal plate cistern, and the dependent portions of the Sylvian fissures (Figure 1).
The tumor extended into the prepontine and interpeduncular cisterns
. The mass measured approximately 3.6 cm transversely and 4.2 cm in the anteroposterior plane.
In most cadaveric dissection, Liliequist's membrane was composed of two distinct leaves: A diencephalic leaf directed toward the diencephalon (separated chiasmatic and interpeduncular cisterns
) and a mesencephalic leaf directed toward the mesencephalon (separated interpeduncular and prepontine cisterns).