Case Reports Visualization of Right Atrial Thrombus Associated with Constrictiva Pericarditis by Indium-111 Oxine Platelet Imaging

A right atrial thrombus is not often seen and only a few reports of visualization have been described. We report a 44-yr-old man who had a large atrial thrombus associated with constrictive pericarditis. Two-dimensional echocardiography and computed tomography showed a large right atrial mass, lndium-111 oxine platelet deposition was demonstrated on the surface of thrombus by platelet imaging. Platelet imaging was useful for differential diagnosis from cardiac tumor, and as an indication for surgical treatment, since right atrial thrombus may have a high risk of pulmonary embolism or severe right heart failure. J NucÃ-Med 28:1344-1347,1987 De etection of intracardiac thrombi is very important in determining the application of anticoagulant therapy or surgical treatment, since patients with such thrombi are at risk for systemic embolism (1). At present, two-dimensional echocardiography, computed tomography and indium-111 ("'In) oxine platelet imaging can be used for the noninvasive diagnosis of intracardiac thrombi (2-4). Left-sided cardiac thrombi are often associated with myocardial infarction, dilated cardio-myopathy or mitral valve disease. On the other hand, right-sided cardiac thrombi are less often seen and only a few case reports of right atrial thrombi have been described in the literature (5-7). We encountered a patient who had a large right atrial thrombus associated with constrictive pericarditis, which was differentiated from cardiac tumor by ["'In]oxine platelet imaging. CASE REPORT A 44-yr-old man was admitted to our hospital with a 4-yr history of progressive dyspnea on exertion. On admission, physical examination revealed an irregular pulse at 52/min and a blood pressure of 114/74 mmHg. A grade 3 diastolic rumbling murmur was audible best at the apex. Moderat