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Background
Hepatic alveolar echinococcosis (HAE) is a serious zoonotic infection that affects humans caused by the fox tapeworm Echinococcus multilocularis larvae. Occasionally, it shows the imaging features of an invasive tumor-like lesion, due to its infiltrative pattern. Alveolar echinococcosis is endemic in Asia, central Europe, and North America. Radiologists should be aware of the imaging findings of HAE, due to the diagnostic and management value of imaging. The purpose of this educational exhibit is to describe ultrasound (US), CT, and MRI findings of HAE and define the most common imaging findings, along with the prevalence and distribution of those findings. A literature review was conducted on the diagnosis and treatment of HAE, with a focus on specific characteristics that may aid in refining the differential diagnosis of these liver lesions.

Educational Goals / Teaching Points
To demonstrate the imaging findings of HAE on different radiological modalities and to illustrate the diagnostic and therapeutic features of this radiologically challenging pathology, which can sometimes be confused with malignant pathologies.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
In humans, the lesions of alveolar Ecchinococcus often resemble cancer in morphology. It proliferates indefinitely via exogenous budding, and this feature enables it to generate metastases via the bloodstream in distant tissues. HAE imaging features are variable and may lead the reporting radiologist to misdiagnosis. Imaging findings of HAE may resemble hepatocellular carcinoma, cholangiocarcinoma, and metastases. US, CT, and MRI work well together to aid in the diagnosis and treatment. Also, with the use of dual energy CT (DECT), virtual nonenhanced imaging is found to be comparable with actual nonenhanced imaging when evaluating HAE, leading to significant reduction in radiation dose. On US, CT, and MRI, HAE can be seen as few or multiple inhomogenous lesions with irregular/indistinct contours, which include cystic-necrotic areas and multiple distributed calcific foci. Pseudocystic, hemangioma-like, metastasis-like appearances may be seen. HAE lesions are often big in size.

Conclusion
HAE can present with a variety of imaging findings and can pose a diagnostic challenge for radiologists, particularly in areas where the disease is not prevalent. With the possible impact of this educational exhibit, it is hoped that these common imaging findings may aid radiologists to be able to diagnose HAE accurately and timely.