Role of radionuclide imaging in the diagnosis of postoperative infection

Postoperative infections are a serious cause of morbidity and mortality and are difficult to diagnose. Signs and symptoms that are generally associate d with infection may be masked by, or mistaken for, normal postoperative ch anges. Anatomic imaging modalities provide high-quality anatomic detail and are the procedures of choice in affected patients because of their availab ility, ease of performance, accuracy, and value in the selection of treatme nt options. However, radionuclide studies demonstrate physiologic processes , which often precede anatomic changes, and can help distinguish normal pos toperative inflammation from infection. Radionuclide studies are also usefu l in identifying complicated orthopedic infections, in which the often exte nsive distortions produced by metallic hardware can confound the interpreta tion of anatomic images. Of the three agents (gallium-67 citrate, indium-11 1-labeled leukocytes, technetium-99m-labeled leukocytes) that are currently approved in the United States for imaging of infection, In-111-labeled leu kocyte imaging is the procedure of choice for diagnosing postoperative infe ction. Gallium scintigraphy is best reserved for those situations in which leukocyte imaging is not available or there is concern that the suspected i nfection may not incite a neutrophil response. In general, the value of rad ionuclide imaging is maximized when used only in those patients for whom th e results of anatomic imaging are negative, nondiagnostic, or at odds with the clinical impression.