Morphometric Study of the Midsagittal MR Imaging Plane in Cases of Hydrocephalus and Atrophy and in Normal Brains
Yoram Segeva,
Ur Metsera,
Liana Beni-Adania,
Chanoch Elrana,
Irith-Irena Reider-Groswassera and
Shlomi Constantinia
a From the Radiology Department, Neuroradiology Unit (S.Y., M.U., R.-G.I.-I.) and the Neurosurgery Department (B.-A.L., E.C., C.S.), Sourasky Medical Center, Tel-Aviv, Israel.
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FIG 1. A, Normal midsagittal spin-echo T1-weighted MR image of the brain (400/12 [TR/TE]).
B, Schematic representation of the parameters, which are defined in the text.
A, chiasmal line; B, third ventricular line; C, callosal line; D, callosal height; E, anterior callosal height; F, mammillocommissural distance; G, mammillopontine distance; H, third ventricular splenial distance; I, spleniochiasmal distance.
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FIG 2. Hydrocephalus secondary to aqueductal stenosis.
A, Spin-echo T1-weighted image at 400/12. When compared with normal appearance in fig 1, there is clockwise rotation of the chiasm, the mammillopontine distance is decreased, the mammillocommissural distance is increased, and the third ventricular floor is concave with consequent counterclockwise rotation of its line.
B, Following endoscopic third ventriculostomy, there is a significant improvement but not normalization of midline appearance. The change in ventricular size was minimal and difficult to appreciate in the axial plane.
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FIG 3. Shunt overdrainage. Spin-echo T1-weighted image at 500/15. Following surgery for marked hydrocephalus secondary to aqueductal stenosis, the classic clinical and radiologic pictures of overdrainage were present. Note beyond normal changes of midline structures, including reversal of the mammillary body ratio. Following third ventriculostomy, with marked clinical improvement, midline structures changed in the expected direction (not shown). Encephalomalacic, including cystic, changes are present in the corpus callosum secondary to impingement. FIG 4. Marked atrophy in a case of long- standing multiple sclerosis. Spin-echo T1-weighted image at 400/12. Relations between midline structures are similar to those of normal brain
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