*4.2.2 Computed tomography*

Sometimes, the ultrasound does not help much in the diagnosis of liver hydatidosis for different reasons, such as obesity, presence of abundant intestinal gas, hydatid recurrence, or residual cavities secondary to previous surgery. When that is the case, CT is used, taking advantage of its higher sensitivity and specificity. Unenhanced CT allows to have a better radiological diagnosis of the different forms of cyst calcification [33]. The contrast-enhanced CT aids in choosing the best surgical techniques according to the different forms of presentation or complications related to the disease, e.g., by allowing a more accurate appreciation of the involvement of the vasculature and biliary tree. CT also aids in diagnosing the cystic migration to the thorax and the biliary tree [35, 36]. Another advantage of the use of contrast-enhanced CT is to achieve a better differential diagnosis from other focal liver lesions [37] (**Figures 5–11A**, **B**).

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**Figure 6.**

*Contrast-enhanced CT. Septated cyst (white arrow).*

**Figure 5.**

*Surgical Treatment of Hepatic Hydatidosis DOI: http://dx.doi.org/10.5772/intechopen.86319*

*4.2.4 Endoscopic retrograde cholangiography*

*Unilocular cyst (CE1, white arrow). Detached membrane. Cyst (CE2, white star).*

MRI is useful for diagnosis of cases of cholangiohydatidosis. Compared to US and CT, the MRI T2-weighted sequence is better at defining the internal structure of the cyst. In general, it is indicated for patients that present difficulties when performing ultrasound, such as bowel gas excess, previous surgeries, disseminated hydatidosis, and obesity. In addition, MRI is recommended when CT is contraindicated due to comorbidities. MRC is used to determine the existence of cysto-biliary fistula and the presence of hydatid material in the biliary tree. It also visualizes the cysto-biliary fistula both toward the bronchi and to the biliary tree [38, 39]

The rupture of a hydatid cyst in the intrahepatic bile duct can initiate some complications, which might become serious mainly due to the development of

*4.2.3 Magnetic resonance imaging*

(**Figures 11a**, **b**–**17**).

#### *Surgical Treatment of Hepatic Hydatidosis DOI: http://dx.doi.org/10.5772/intechopen.86319*
