A 66-year-old man had shortness of breath and a clear chest x-ray. Tc-99m MAA perfusion study revealed a moderate-sized, wedge-shaped defect in the left upper lobe seen on oblique images. Neither the posterior perfusion view, nor the posterior xenon-133 ventilation scan demonstrated the abnormality. However, correlation to a previous chest CT established that this defect was due to a hypertrophic left first costosternal articulation. A confident reading of "normal" was rendered. Awareness of such artifactual causes of perfusion defects is important in the interpretation of radionuclide lung scans.
From the Nuclear Medicine Department, Crawford Long Hospital, Emory University System of Health Care, Atlanta, Georgia
Received for publication November 7, 1996; accepted December 19, 1996.
Reprint requests: David M. Schuster, M.D., Division of Nuclear Medicine, Emory University Hospital, Room E145, 1364 Clifton Road, NE, Atlanta, GA 30322.