Our study included 35 men and 20 women,
between 11 and 72 years.
Median age was 46.5 years.
Five of them had a known medical history of hydatid disease.
In the different imaging techniques intrahepatic cystic lesions were shown (localised in the right lobe in 23 cases): hypoechoic on US,
hypodense with a non enhanced wall on CT and T1 hypointense,
T2 Hyperintense with a characteristic T2 hypointense wall on MRI.
Cysts were type 1,
2 and 3 of Gharbi classification in 85 % of the cases.
Rupture occured into the commun hepatic duct (9 cases),
in the lobar biliary branches specially the right one (12 cases),in the small inrahepatic bile ducts (31 cases) and in the gallbladder(3 cases).
1- INDIRECT SIGNS:
US is the first imaging exam to be performed.
Although it is not specific,
it helps suggesting the diagnosis.
In our study indirect signs of intra biliary rupture were noticed in all cases such as:
- Deformation of the cyst (42%)
- Crampled or detached hydatid membrane (60%)
- Dilatation of the biliary tree ( 100 %)
- Close contact between the cyst and a bilairy branch ( 61%)
- Interrupted calcified or not cystic wall (46 %)
- Fluid-fat level in the cyst (1 case)
- Distented gall bladder (2 cases)
Cysto biliary communication leads to infection,
explaining the thickening of biliary wall found in 30 % of cases
2- DIRECT SIGNS:
The diagnosis is reinforced by the visualisation of the cysto-biliary communication itself which is sometimes associated with germinative membrane or daughter vesicles in th biliary duct lumen,
if a large duct is involved.
MRI is the most sensitive technique.
In fact MRCP and T2 weighted sequence are very important.They show a focal defect of the hypointense cystic wall communicating with a dilated biliary duct.
In case of a large communication,
US and especially CT may demonstrate cysto-biliary fistula.
Intra biliary daughter vesicles (nodular strutures),
fragmented germinative membrane (irregular linear strutures) and hydatic sand are un unequivocal sign of communicating rupture and have some caracteristic features in different techniques:
-Hyper and sometimes hypoechoic on sonography.
-Hyperdense in CT and T2 hypointense in MRI.
They should be differentiated from the other possible intra biliary content such as sludge,
blood,
pus,
parasites,
and non shadowing calculi.