High Signal Intensity of the Septum Pellucidum at MR Imaging:Significance in Hydrocephalus

ABSTRACT

PURPOSE: To evaluate the significance of high signal intensity of the septum pellucidum in hydrocephalus on proton density-weighted brain MR images. MATERIALS AND METHODS: Authors reviewed the MR images of 418 cases of patients with normal(175 cases), hydrocephalic(35 cases), atrophic(58 cases), and other groups(150 cases) retrospectively. We analyzed the signal intensity of the septum pellucidum in the normal group and the incidences of high signal intensities of periventricular area of frontal horn of lateral ventricle(area 1), periventricular area except area 1(area 2), callososeptal area(area 3), and septum pellucidum(area 4) in the normal and abnormal groups. RESULTS: In the normal group, the septurn pellucidum was isointense to the head of caudate nucleus on proton density-weighted image. High signal intensity of the septurn pellucidurn was seen in 31 cases (22 cases of hydrocephalus, 5 cases of brain atrophy, and 4 cases of others), and showed high specificity(91.4%) for hydrocephalus in spite of low sensitivity(62.9%), as compared with periventricular hyperintensities of other areas. CONCLUSION: High signal intensity of the septum pellucidum on proton density-weighted image may be caused by transependymal CSF migration in the patients with hydrocephalus, and considered as an additional finding of hydrocephalus in the cases of ventriculomegaly.