MR imaging of an intracerebral hydatid cyst.

We describe the CT and MR findings in a 1 0-year-old boy who presented with a 5-year history of headache, often relieved by vomiting. He had had a seizure approximately 1 year prior to admission and a second seizure 1 month before admission. The patient had performed poorly in school. On examination, there was a left-sided weakness and bilateral papilledema. The boy lived on a farm , where he played with dogs and other animals . CT scans obtained upon admission demonstrated a large cystic lesion in the right parietal area extending to the inner table of the skull (Fig. 1A). There was marked compression of the right lateral ventricle and displacement of midline structures to the left. The density of the cyst 's contents was similar to the CSF in the lateral ventricles. There was no enhancement of the lesion and no associated calcification. Ventricular dilatation was associated. Axial and coronal spin-echo MR images, 600/20/2, 2000f40f2 , and 2000/80/2 (TR/TE/ excitations), confirmed the sharply demarcated, spherical, cystic lesion. In both the 600/20 and 2000/80 images, the signal intensity of the cyst's contents was identical to the CSF of the lateral ventricles (Figs. 1 B and 1 C). On the 2000/40 images there was periventricular increased signal intensity consistent with transependymal permeation of CSF secondary to some compression of the foramina of Monro. On the 2000/80 images there was a thin rim of low signal intensity around the cyst. Prior to surgery, antiparasitic therapy for hydatid disease was instituted . At surgery , the classic pearly white appearance of a hydatid r.yst was seen projecting to the surface of the brain (Fig. 1 D). Pathology confirmed the diagnosis of a hydatid cyst demonstrating viable scoleces. After surgery , a repeat CT scan revealed ventricular dilatation, which responded to a ventriculoperitoneal shunt. Three months after discharge, the child appeared well . Discussion