Cerebral hydatid cysts: CT findings.

The CT features of cerebral hydatid cysts are divided into two groups. In the unilocular cases, the cyst is large, spherical in shape with sharply defined borders. One side of the cyst wall is very close to the calvarium. The cyst may calcify and may have septae inside. There is no enhancement with contrast media and also no edema surrounding the cyst. In the second group there are multiple and small multilocular cysts. These cysts are in ovoid or polygonal forms like a bunch of grapes, with perifocal edema. After contrast media administration, there is enhancement in the cyst wall. In one case there were numerous cysts in both hemispheres.