Cerebral hydatid disease: CT and MR imaging findings

Cerebral hydatid disease is very rare, representing only 2% of all cerebral space occupying lesions even in the countries where the disease is endemic. The aim of this paper is to describe the characteristic features of cerebral hydatid disease in computed tomography (CT) and magnetic resonance imaging (MRI). We retrospectively reviewed the CT and MR imaging findings of 18 patients with pathologically confirmed cerebral hydatid disease over a period of 13 years (1990-2002). The study group consisted of 17 cases of Echinococcus granulosus and 1 case of Echinococcus multilocularis (alveolaris). They were 12 male (66.7%), and 6 female patients (33.3%), ages ranging from 7 to 50 years with an average age of 20.3 years. Headache, vomiting and seizures were the predominant symptoms. Papilloedema was present in 14 patients (77.7%). Common CT and MR imaging findings of E. granulosus lesions were welldefined, smooth thin-walled, spherical, homogeneous cystic lesions with no contrast enhancement, no calcification, and no surrounding oedema. The lesion seen with E. multilocularis was a well-defined multiseptated mass consisting of solid and cystic components with calcification in the solid portion. Cystic lesions with surrounding hyperintensity of perifocal oedema with complete or incomplete rim enhancement were seen in two patients, and were labeled as complicated and infected cysts. Although cystic cerebral hydatid disease is well demonstrated by CT and MR examinations, CT is superior in detecting calcification in the cyst, when present, MR is better in demonstrating cyst capsule, detecting multiplicity and defining the anatomic relationship of the lesion with the adjacent structures, and it is more helpful in surgical planning.