Fasciola hepatica – Parasite infection witch is often found in developing countries. Humans are infected accidentally by drinking contaminated water, eating freshwater plants and et cetera. Parasites migrate from GI tract to the liver, then invade the biliary tract where adult flukes live. In advansed cases they move to the peritoneum and penetrate into various organs ( lung, heart, brain, skin... ).

During hepatic phase MR images may show hepatomegaly and focal thikening of the liver capsule due to the penetration of parasited into Gleson’s capsule. MRI demonstrates capsule pseudotumors with T2WI hyper or slightly hyperintense signals and DWI restriction. MRI findins of hepatic fascioliasis include multiple usualy subbcapsulad round or oval small lesions with low signal intensity on T2Wi arradned as „tunnels and caves“ - „cluster sign“. These lesions have peripherial enhancement in early arterial phase after contrast administration. „Claster sign“ is associated with pyogenic hepatic abscesses and differential diagnosis includes metastases, infarction, biliary cystadenocarcinoma and mycobacterial infection. A large  cystlike necrotic lesion may also be observed. The  biliary phase – when adult flukes invade in the bile ducts and MRI demonstrates biliary tructs dilatation by produce a mechanical obstruction, mucosal inflammation, adenomatous hyperplasia and periductal fibrosis. Cholecystitis and angiocolitis are common due to obstruction of bile ducts. Inflammation is manifested by thickening of the walls of bile ducts, DWI redtrictions and hyperenhancment. Therefore it is necessary to make a differential diagnosis with cholangiocarcinoma. Intraductal flukes may visible as filling defects on MRCP. In the parenchymal phase we may sometimes notice a worm. [Fig.1.2]

Subcapsular hematoma is a rare complication of the hepatic phase, which is present as T1WI hyperintense rim shape lesion. Subcapsular hematoma associated with peripheral eosinopilia is a sign not only of fasciolitis, but olso of polyarterytis nodosa.

The imaging findings of granuloma differ according to type. Athough MRI is the best radiological study for diagnosing this disease, there still are some pitfalls.  DWI resttriction is characteristic to both inflamation and neoplasia, which frequently becomes the cause of error; Fatty liver and cirrosis accompanyng lesion makes us think of its other origin. The differential diagnosis included nodular liver pathologies, liver metastaese and  primery mallignant neoplasms such as hepatocellular carcinoma and cholangiocellular carcinoma. 

 Caseating granuloma mainly refers to tuberculous granuloma. Abdominal tuberculosis is  rare form of infection with mycobacterium tuberculosis. Caseaus necrosis develops in the core of tuberculoma, therefore lesion has a necrotic center. Radiologic features usually are non specific. May develop hepatomegaly or hepatosplenomegaly.  A granuloma can be detected as small nodules ( micro or macronoduled ) or large mass. Nodules can be multiple or single. MRI imaging findings of granuloma: isointense or hypointense on T1WI, hyperintense on T2WI, hyper or slightly hyperintense onT2 STIRR and variable on T1C+(Gd). [Fig.3].

 Non caseating granulomas scattered throught the liver in the  most common presentation of multisystem sarcoidosis (Boeck’s). The pathophysiology remains unknown. They have no specific features and usualy range from submillimeter to two centimeters in size. Large lesion has a greater amount of reticulin and is bounded by fibrotic hepatic parenchyma, due to a more strong immune response to the unknown causative agents. Granuloma appears as hypointense on T1WI, T2WI and STIRR weighted imaging sequences. They become rapidly isointense or hyperintense to liver parenchyma after intravenous contrast administration, with persistent enhancement. MR imagings show hepatomegaly or hepatosplenomegaly. Sarcoidosis is as usually characterized by portal lymphadenopathy. [Fig.4].

 The fibrin ring granulomas can be found in infections, in Hodgkin lymphoma or may be  drug induced. These granulomas MRI features are nonspecific but because fibrous component, they are seen as bulk lesions, which are hypovescular but show delay enhancement.

Eosinophilic granuloma is caused by chronic inflammation, autoimmune disease, or drug reactions. MRI will reveal T1WI isointensity, T2WI  hiper or isointensity and  T1Gd  isointensity in arteryal phase and iregular low signal in venous phase. [Fig5].