Dominique A. Hepatic Alveolar Echinococcosis HAE is a rare but life-threatening parasitic disease which has the feature of infiltrating growth like tumor. It is necessary to look into those imaging development to establish an optimal strategy for HAE diagnosis. US is the first choice due to its widespread availability, radiation-free and low costs. It has limited contribution for small peripheral lesions, and is unsatisfactory in the evaluation of extension into the adjacent periparasitic liver.
Though radiation is the drawback of CT, it remains the mainstream modality for morphologic imaging assessment of HAE lesions in most of developing countries or districts. CT has a clear superiority over MR and US, particularly in demonstrating calcification, especially in small clusters. It also helps to stage the disease and provide comprehensive information about vascular, biliary, and extrahepatic extension. With high resolution for soft tissue and without any radiation, MRI is the best modality for characterizing the parasitic lesions and depicting vascular or biliary tree involvement and extra-hepatic extension.
It provides valuable information in surveillance of the efficacy of chemotherapy. Its value in detecting metastases has still to be evaluated. Yet it is costly and not readily available, so it has a limited availability, especially in those developing countries and districts.
Micro-bubble contrast agents have been developed to improve US imaging and the technique of CEUS was proposed for the diagnosis and evaluation of HAE lesions in both human beings and in the rat model Zeng Hongchun et al. CT perfusion provides an interesting functional imaging for detecting the micro-circulation of HAE. It shows different levels of blood perfusion on the margin, center of HAE and nearby hepatic perenchyma.
Energy spectral CT, with much lower radiation, demonstrates the same changes in blood supply of HAE by measuring iodine concentration instead of CT perfusion.
