Right atrial free-floating thrombus in a patient with massive pulmonary embolism: a case of 'emboli in transit'.

A 78-year-old man was admitted with sudden onset of dyspnea followed by syncope. Contrast-enhanced computed tomography showed embolism in the right main pulmonary artery and left upper pulmonary artery. Echocardiography revealed a large, free-floating thrombus and cine magnetic resonance imaging showed highly mobile, low-signal intensity mass in the right atrium, which protruded into the right ventricle during diastole. During surgery the thrombus migrated into the pulmonary artery trunk, but it was successfully removed.