Subependymal giant cell astrocytoma (SEGA) is a clinically benign brain tumor associated with tuberous sclerosis complex (TSC). There are still controversies on early diagnosis of the tumor.
CT and MR imaging of 20 patients with pathologically confirmed SEGA were retrospectively reviewed. Two radiologists evaluated the location, shape, size, number, edge, cerebral edema, homogeneous or heterogeneous appearance, attenuation and signal intensity, degree of enhancement and calcification of lesions. Their prognoses were based on clinical observations.
SEGA showed similar features in imaging: an extra-axial, well-circumscribed, periventricular mass, isodense or slightly hyperdense on CT, hypointensity on T1-weighted imaging and isointensity to hyperintensity on T2-weighted imaging. The mass enhanced markedly and heterogeneously after the administration of contrast agent. Subependymal nodules were demonstrated in 5 cases. Remarkably, 17 patients (85%) showed ventricular dilatation and 14 patients (70%) showed calcification in CT and MR imaging. Moreover, perifocal edema was not significantly near the masses. Four cases are associated with tuberous sclerosis complex (TSC).
Although there are no pathognomonic imaging findings for SEGA, the following clinical and imaging features might be helpful for the diagnosis, such as the initial age of first or second decade, typical location in the periventricular regions adjacent to the foramen of Monro, hydrocephalus accompanied with raised intracranial pressure, TSC and marked heterogeneous enhancement.