False perfusion defect on myocardial perfusion SPECT induced by sternal tumoral uptake

A 61-year-old man with chronic chest pain was referred for a myocardial perfusion scan. Following dipyridamole infusion, 99mTc-MIBI was injected and the reconstructed images showed decreased activity in the anteroseptal wall, which prompted the supervising physician to review the cinematic data. Reviewing the cinematic images revealed abnormal 99mTc-MIBI uptake by the ribs, clavicles, and more intensely in the sternum. The next morning, whole-body planar imaging was performed 20 minutes after injection of 99mTc-MIBI at rest, which again revealed widespread abnormal 99mTc-MIBI uptake. Subsequently, a skull X-ray showed multiple areas of osteolysis, typical of punched-out lesions. In view of this evidence, the patient underwent bone marrow aspiration, which revealed marked plasmocytosis and confirmed the diagnosis of multiple myeloma. Our case indicates a false positive perfusion defect induced by sternal sestamibi uptake secondary to sternal tumoral involvement. As the sternum is in close proximity to the myocardium, the effects of its unusual radiotracer uptake on the pattern of myocardial perfusion can be significant. The interpretation of a myocardial perfusion scan should not be limited to the heart and, as the ultimate goal is the patient's wellbeing, any available information should be interpreted.