MRI misinterpretation of spontaneous echo-contrast as a large left atrial thrombus.

A magnetic resonance imaging of the heart was obtained in a patient with history of mitral valve replacement, in whom cor triatriatum dexter was suspected. Dense left atrial echo-contrast, visualized during a previous transesophageal echocardiography, was incorrectly interpreted as a large thrombus extending into the pulmonary veins and the patient was referred for cardiac surgical evaluation.