Hydatid disease (echinococcosis) is a parasitic infection caused by the lar
val stage of the tapeworm Echinococcus. In humans, the two main forms are c
ystic hydatid disease, caused by E. granulosus, and less frequently alveola
r hydatid disease, caused by E. multilocularis. They can be found in variou
s sites in the body. The purpose of this essay is to illustrate the CT appe
arances of cystic and alveolar hydatid disease in various locations.