Hepatic alveolar echinococcosis: MRI findings

The purpose of this study was to describe the magnetic resonance imaging (MRI) appearance of hepatic alveolar echinococcosis (HAE) on T1-weighted, T2-weighted and postgadolinium images. A total of 13 lesions were demonstrated in 13 patients. All patients underwent MR examination at 1 T imager. MR examinations included precontrast T1-weighted breathing averaged spin echo (SE), breath-hold spoiled gradient echo, T2-weighted TSE sequences with and without fat suppression, and T1-weighted breath-hold spoiled gradient echo (SGE) sequence following i.v. after gadolinium administration. All lesions were confirmed with histopathology. HAE hepatic lesions revealed geographic patterns of variable signal intensities on noncontrast T1- and T2-weighted images. Slightly hyperintense, iso- and hypointense signal on T1-weighted images corresponded to calcified regions, which appeared hypo-isointense signal on T2-weighted images. Necrotic areas were hypointense signal on T1-weighted and hyperintense signal on T2-weighted images. On postgadolinium images, lesions did not reveal enhancement. Dilatation of intrahepatic bile ducts distal to HAE abscesses were observed in five patients and portal vein invasion or compression was observed in four patients, lobar atrophy of the liver was coexistent finding in cases with portal vein compression. The MRI appearance of HAE abscesses included large irregularly marginated masses with heterogenous signal on T1- and T2-weighted images and lack of enhancement with gadolinium.