Radiological classification of hydatid cyst:
Fig. 3: CLASSIFICATION OF HYDATID CYSTS
Fig. 4: CLASSIFICATION OF HYDATID CYSTS
Sites of involvement(5)
Fig. 2: INCIDENCE AND SITE SPECIFIC COMPLICATIONS OF HYDATID DISEASE
References: Eckert J, Gemmell MA, Meslin FX, Pawlowski ZS: WHO/OIE manual on echinococcosis in humans and animals: a public health problem of global concern. Paris: World Organisation for Animal Health, 2002; 20–72
- Liver is the most commonly affected organ (68 to 75% of cases),
with the right lobe being the most frequently involved portion.
- Imaging findings in hepatic HD depend on the stage of cyst growth
- Complications such as rupture into the biliary tree or transdiaphragmatic migration to involve the thoracic cavity can occur.
Fig. 5: Hepatic Hydatid cyst.
Axial CT scan (b) Coronal CT scan demonstrates trilaminar pattern of the hepatic hydatid cyst with separation of the endocyst and fine peripheral enhancement of the cystic walls.
Fig. 6: (A) USG image, (B) axial T2 MRI (C) representative pic (D) Axial CT demonstrating cyst with a predominantly thick membranes.
Fig. 7: Hepatic hydatid with cart wheel like appearance.
Axial CT scan of liver and USG demonstrates hepatic hydatid cyst with multiple daughter cyst giving cart wheel like appearance with partial cyst wall calcification.
Fig. 8: A) Axial and (B) Coronal T2w MRI of liver demonstrates hepatic hydatid cyst with multiple daughter cysts in right lobe of liver.
Fig. 9: (A) and (B) Axial MRI, (C) Axial CT (D) representative image demonstrating cyst with calcified wall and internal contents, representing an involuting/ degenerating cyst.
- Pulmonary lesions can be primary or secondary to intrathoracic rupture of a hepatic hydatid cyst.
It can also involve the pleural cavity,
mediastinum and chest wall.
- Pulmonary cysts may range between 1 and 20 cm in diameter.
Larger lesions cause mediastinal shift,
can induce a pleural reaction or cause atelectasis of adjacent lung.
Calcification of pulmonary cysts is rare .
- Computed tomography (CT) scan may demonstrate a thin enhancing rim if the cyst is intact.
The contents of closed simple cysts are homogeneous and show fluid attenuation.
Daughter cysts may be seen attached to the endocyst or lying free within the main cyst.
- The MRI characteristics of a hydatid cyst may differ depending on the developmental phase (infected/viable/dead).
On magnetic resonance imaging (MRI),
cysts show low signal intensity on T1-weighted images and high signal intensity on T2-weighted images
Fig. 15: LUNG HYDATID CYST.
Axial CT showing pulmonary hydatid with floating internal membranes, (B) Representative image.
Fig. 16: Pulmonary hydatid with intrabronchial communication (A,B,C), Image D showing air within cyst secondary to bronchial communication
Hydatid cyst can virtually involve any organ and the imaging appearance depends on stage.
Smooth walled cystic lesions with internal septations/ membranes or daugther cysts should help us in considering hydatid disease in the differentials particularly in the endemic areas.
Fig. 11: Adrenal hydatic cyst.
Axial and coronal, pre and post contrast CT scan demonstrates right adrenal gland hydatid cyst, additional hepatic hydatid cyst in segment VIII.
Fig. 12: Renal hydatid. Axial CT scan with thick walled cyst with internal membranes showing enhancement with few daughter cysts within in left kidney.
Fig. 13: Intraperitoneal hydatid cysts
Fig. 14: BONE HYDATID CYST.
(A,B)Axial CT scans demonstrates partial destruction of the acetabulum with adjacent soft tissue component with cystic areas within.
(C,D,E) MRI images in same patient demonstrates Cystic lesion with daughter cysts within suggestive of bony hydatid cyst.
Fig. 17: SPINAL HYDATID CYST
Fig. 18: BRAIN HYDATID CYST.