Mediastinal and heart wall invasion by actinomycosis: CT and MRI appearances

Widespread use of antibiotics facilitates the development of some uncommon chronic infections such as actinomycosis. The clinical and radiographic findings overlap those of other inflammatory and neoplastic conditions. With a review of the literature, we report the CT and MRI findings in a case of thoracic actinomycosis, presenting with right ventricular failure caused by heart involvement. CT was helpful in identifying the mediastinal extent of the disease and in demonstrating the absence of pulmonary involvement. MRI, however, offered complementary information, especially in assessing heart involvement without the need for intravenous contrast media. On T2-weighted images the mediastinal process was noted to be of relatively low signal intensity, possibly indicating its benign nature. The association with heart involvement was suggestive of thoracic actinomycosis.