Sternal Infection and Retrosternal Abscess Shown on Tc-99m HMPAO-Labeled Leukocyte Scintigraphy

We report a case of a 61-year-old man who underwent coronary artery bypass grafting in 1975 and progressively developed chronic sternal osteomyelitis. He was examined for fever with an increase of pain and swelling of thesternal scar. Computed tomographic scan performed 2 weeks before was normal. The patient was referred to the nuclear medicine department for a bone scan. There was a high level of blood-pool activity in the lower thorax in the blood-pool phase, and intense linear midline uptake was observed extending from the lower thorax into the upper abdomen in the late phase. Anterior and posterior Tc-99m HMPAO-labeled leukocyte images of the chest and abdomen obtained approximately 24 hours after injection demonstrated major accumulation in the same location extending to the anterior mediastinum. A control computed tomographic scan for comparison obtained 1 day later demonstrated a large retrosternal abscess with sternal osteomyelitis. This was confirmed at surgery with drainage of pus. Staphylococcus aureus was isolated. The patient was treated with appropriate antibiotics with good effect.