Article Figures & Data
Figures
- Fig 1.
Case 1. A, Sagittal TSE T2 image shows third ventricle enlargement with downward displacement of the floor of the third ventricle consistent with hydrocephalus. The cerebral aqueduct and foramen of Magendie are open widely, showing extensive flow void phenomenon. There is a mild enlargement in the fourth ventricle. There is no sign of obstructive membrane in the prepontine cistern. B, Left parasagittal TSE T2 images through the left lateral ventricular exit show no direct or indirect sign of membrane. C, Axial TSE T2 image through the fourth ventricular exits demonstrates prominent signal intensity void in the fourth ventricle, but there is no direct or indirect sign of obstructive membrane at the foramina of Luschka. D, Left parasagittal 3D-CISS image clearly points out the membrane itself in the foramen of Luschka. There is extensive intensity difference between the fourth ventricle and the neighboring cistern. E, Sagittal 3D-CISS image clearly demonstrates prepontine membranes extending from the clivus to the basilar artery. F, Left parasagittal follow-up 3D-CISS image indicates persistent membrane in the fourth ventricle exit foramen, though the intensity differences between cistern and ventricle have disappeared.
- Fig 2.
Case 2. A, Axial TSE T2 image through the posterior fossa shows left cerebellar hypoplasia and enlargement of the bilateral cerebellomedullary cistern without any evidence of membrane at the fourth ventricle exit foramina. B, Axial oblique reformatted image of sagittal 3D-CISS reveals obstructing membranes of foramina of Luschka, bulging into the cerebellomedullary cisterns.
- Fig 3.
Case 3. A, Sagittal TSE T2 image shows an enlarged third ventricle. The cerebral aqueduct seems to be open. B, Sagittal 3D-CISS demonstrates superior medullary velum synechia, causing triventricular hydrocephalus. There is a spontaneous third ventriculostomy at the floor of the ventricle, just behind the tip of the basilar artery. Sagittal CISS revealed the anatomic defect, whereas cine PC did not detect any flow through the defect.
- Fig 4.
Case 4. A, Sagittal TSE T2 image demonstrates enlarged third ventricle, extensive flow void phenomenon in the cerebral aqueduct, the fourth ventricle, and prepontine/interpeduncular cisterns compatible with communicating hydrocephalus. B, Sagittal 3D-CISS image shows Liliequist membrane just below the downward bulging floor of the third ventricle. In addition to this, there is a thin membrane extending from the clivus to the basilar artery, dividing the prepontine cistern into upper and lower parts. The signal intensity difference between 2 parts with a sharp, linear zone of transition was seen. C, Coronal oblique reformatted image of 3D-CISS through the cisterns demonstrates lateral extension of the prepontine membrane, trapping CSF between the Liliequist membrane and the prepontine membrane. D, During ETV, after the floor of the third ventricle through the Liliequist membrane is opened, a complete membrane without any aperture is seen. E, The same view after the membrane is opened and removed, the cisternal part of the left abducens nerve is seen partly. F, On the follow-up sagittal 3D-CISS image, there is free communication between the third ventricle and the prepontine cistern through the interpeduncular cistern. G, Follow-up coronal oblique reformatted image of 3D-CISS after ETV through the cisterns (same view as in C) reveals nearly complete removal of the prepontine membrane. The difference in signal intensity between the 2 parts of the cisterns has almost completely disappeared.
- Fig 5.
Case 4. A, Axial TSE T2 image through the lateral ventricle demonstrates unilateral right lateral ventriculomegaly. B, Coronal TSE T2 image through the foramen of Monro falsely demonstrates a free communication between the right lateral ventricle and the third ventricle. C, Coronal reformatted sagittal 3D-CISS image points out a complete membranous obstruction in the right foramen of Monro. D, Follow-up axial-oblique reformatted image revealing complete removal of obstructing membrane and normal-appearing lateral ventricles.
Tables
Sequences Imaging Plane TR/TE/ETL Time of Acquisition Voxel Size (mm3) Section/Partition Thickness/Gap (mm) FA/BW (Hz/Px) TSE T2 Axial 3590/101/13 1.53 1.75 5/0.5 90/100 TSE T2 Sagittal 3000/131/13 1.41 1.2 2/0.2 90/100 TSE T2 Coronal 4850/132/13 1.36 1.08 3/0.75 90/100 Cine PC Oblique 59/11/− 3–5 1.08 3 35/391 3D Turbo flash T1 Sagittal 2000/3.9/− 4.14 0.51 0.8 20/130 TSE T1 Axial 500/13/2 2 2.05 5/0.5 70/155 3D-CISS Sagittal 13.6/5.7/− 4.44 0.216 0.6 50/130 Note:—ETL indicates echo-train length; FA, flip angle; BW, bandwidth; TSE, turbo spin-echo; cine PC, cine phase-contrast; 3D turbo flash T1, 3D turbo fast low-angle shot T1; 3D-CISS, 3D constructive interference in the steady state.
- Table 2:
Site of membranous obstruction on the basis of examination of different sequences
Sequences Localization of Obstructive Membranes Total Number of Membranes Foramen of Monro Cerebral Aqueducts Superior Velum Medullary Synechia Foramen of Magendie Foramina of Luschka Foramen Magnum Cisterns Conventional T1 and T2 7* 41 1 4 3 0 1 57 3D CISS 7 41 5 28 46 2 28 157 * These cases were indirectly diagnosed on the basis of unilateral or bilateral lateral ventricular dilation. There are 2 bilateral membranes in 5 cases.
- Table 3:
Classification of hydrocephalus on the basis of examination of different sequences
Sequences Number of Communicating Hydrocephalus Cases Number of Noncommunicating Hydrocephalus Cases with Obstructive Membranes Total Number of Cases with Obstructive Membranes Number of Cases with no Visible Obstructive Membrane Number of Cases with Only an Obstructive Cisternal Membrane Number of Cases with Only an Obstructive Intraventricular Membrane Number of Cases with Obstructive Ventricular Membrane Plus Obstructive Cisternal Membrane Conventional T1 and T2 46 0 47 1 48 3D-CISS 13 7 63 22 92
