Eventration of the diaphragm on radionuclide ventriculography

A 67-year-old man was referred for a radionuclide ventriculogram because of progressive dyspnea. Although the radionuclide ventriculogram demonstrated normal systolic left ventricular function, a large focus of extracardiac activity lateral and posterior to the heart was unexpected. A chest radiograph and subsequent CT scan revealed eventration of the left hemidiaphragm with clear lung fields and no evidence of a pulmonary arteriovenous malformation. The scintigraphic abnormality was caused by physiologic blood pool activity within the spleen, which was displaced upward due to the congenitally hypoplastic diaphragm.