Imaging Findings in Liver Hydatidosis: Pictorial Assay Poster No.: C-1790 Congress: ECR 2014 Type: Educational Exhibit Authors: A. S. Eksioglu, B. Ucan, E. Çakmakc#, P. S. Öztekin, M. Pala Akdogan; Ankara/TR Keywords: Parasites, Infection, Cysts, Diagnostic procedure, Ultrasound, MR, CT, Paediatric, Liver, Abdomen DOI: 10.1594/ecr2014/C-1790 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myesr.org Page 1 of 18
Learning objectives We aim to assess different ultrasound (US), Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) findings in liver hydatidosis at different stages of the disease. US is the modality of choice for diagnosis. The sonographic findings revealing the morphology and structure of the hydatid cysts are accepted to correspond to their evolutionary stage. Therefore, classifications are generally based on the ultrasound findings. CT and MRI are mainly useful in obese patients, extraabdominal disease, or complications and for planning surgery or interventional therapy. Page 2 of 18
Background Hydatid disease is a parasitic infection caused by the larval stage of four different types of Echinococcus cestodes. Humans are the accidental dead-end intermediate hosts for the parasite which develop cysts after ingesting the parasite's of liver passed from an infected carnivore like a dog which are definite hosts. Echinococcus granulosus is the endemic type in Turkey and its cysts are most commonly found in liver (up to 80% of the cases) followed by lungs by approximately 20% [1]. The definitive diagnosis of liver echinococcosis requires a combination of imaging, serologic, and immunologic studies [2]. US, being cost-effective, accessible, radiation free and having a high sensitivity ranging from 93% to 98% has become the preferred modality in imaging of liver hydatidosis [3,4]. It is successful in demonstrating the inner structure of a hydatid cyst and depicting specific signs like undulating membranes and is also an efficient way to examine the relationship of intrahepatic and extrahepatic bile ducts with the cyst [5, 6]. The sensitivity of CT ranges from 90 to 98% [3,4]. Two major disadvantages of CT are cost and radiation. MRI is reported to reproduce the ultrasound-defined features of hydatid cyst better than CT [7]. When used with MR cholangiography it is a valuable technique to assess the biliary tree and any cysto-biliary fistula-related complications [8]. Page 3 of 18
Findings and procedure details World Health organisation (WHO) standardized classification of echinococcus granulosus is based on ultrasonographic images and describes 5+1 different stages corresponding to the parasite's normal developmental stages [9]. CL is active unilocular cyst with uniform anechoic content and not clearly visible cystic wall (Fig. 1 on page 5) ; CE1 is active unilocular cyst with uniform anechoic content and cystic wall well visible (Fig. 2 on page 5 Fig. 3 on page 6) ; CE2 is active multivesicular, multiseptated cyst with cystic wall well visible (Fig. 4 on page 7 ); CE3 is active unilocular cyst with inner floating detached membrane (Fig. 5 on page 8 Fig. 6 on page 9) ; CE4 is an inactive cyst with pseudotumor, solid sonographic pattern (Fig. 7 on page 10 Fig. 8 on page 11 Fig. 9 on page 12) ; CE5 is a cyst with calcified wall (Fig. 10 on page 13 ). Large CE1, CE2 are regarded as "active", CE3 as "transitional" and CE4 and CE5 as "inactive" cyst stages. 'Cyst wall calcification' is not considered as a stage defining finding by itself, as recently shown in a large data set [10] ( Fig. 10 on page 13 Fig. 11 on page 14). In this educational poster exhibit US images for different stages, showing some characteristic sonographic appearances of liver hydatidosis are given along with some examples of CT and MR findings from our archive. Page 4 of 18
Images for this section: Fig. 1: CT image shows a small solitary active unilocular cyst with uniform anechoic content and not clearly visible cystic wall (WHO type CL) located at segment 8. Page 5 of 18
Fig. 2: US image shows a large active unilocular simple cyst with uniform anechoic content and cystic wall well visible (WHO type CE 1) at subcapsular location in segments 2/4. Page 6 of 18
Fig. 3: US image demonstrates a simple thick-walled cyts with slightly detached endocyst (WHO type CE 1) in segment 8. Another simple cyst with visible walls (WHO type CE 1) in segment 2 is also partially visualized. Page 7 of 18
Fig. 4: T2 weighted MR image shows large WHO type CE 2 subcapsular cysts both in liver and spleen which pose a risk for rupture. Note that T2 weighted MR image demonstrates the internal details of the cysts successfully. Page 8 of 18
Fig. 5: US image of a patient with liver hydatidosis shows detached folating membranes in a cyst in segment 6 (WHO type CE 3). Page 9 of 18
Fig. 6: CT image of the same patient as in Figure 8 fails to demonstrate the floating detached membranes of a WHO type CE 3 hydatid cyst as clearly as US. Page 10 of 18
Fig. 7: PA chest X-ray of a pediatric patient with liver hydatidosis shows the elevation of right hemidiaphragma. Page 11 of 18
Fig. 8: US image of the same patient in Figure 4 demonstrates complex solid-cystic multivesicular hydatid cyst ( WHO type CE 4) in segments 7/8. Round daughter cysts,collapsed endomembrane and debris form the appearance of pseudotumor. Page 12 of 18
Fig. 9: CT image of the same patient in Figure 3 and 4. A large subdiaphragmatically located distended cyst with internal septations is seen in segments 7/8. Note that US demonstrates more internal details for this cyst than CT does. In this image cyst apeears to be WHO type CE 2 by CT features (it is WHO type CE 4 by US). Page 13 of 18
Fig. 10: CT image of a patient with multiple hydatid cysts some with wall calcifications. (WHO type CE1) and some totally calcified and inactive (WHO type CE5) (arrow). Page 14 of 18
Fig. 11: Coronal T1 weighted MR image of a patient with hydatid cyst located in segment 3/4 shows the thick wall and wall calcifications. Page 15 of 18
Conclusion Although a rare diagnosis in western Europe or USA, in endemic countries like Turkey a cystic lesion in liver is very frequently a hydatid cyst. A radiologist, especially if practicing in one of these endemic locations, should be aware of its classical appearances and staging. Ultrasound gives information about the 'activity' status of the lesion and can help determining the type of treatment. CT and especially MRI are helpful in selected cases. Page 16 of 18
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10. Hosch W, Stojkovic M, Janisch T, Kauffmann GW, Junghanss T. The role of calcification for staging cystic echinococcosis (CE). Eur Radiol. 2007 Oct;17(10):2538-45. Page 18 of 18