COMPARISON OF TC-99M INFECTON IMAGING WITH RADIOLABELED WHITE-CELL IMAGING IN THE EVALUATION OF BACTERIAL-INFECTION

Background Bacterial infection can pose a substantial diagnostic dilem ma. Techniques involving radiolabelled leucocytes can pinpoint the sit e of inflammation. However, previous radiolabelling techniques have fa iled to distinguish between bacterial-mediated infection and non-bacte rial inflammation. To overcome this difficulty, we have studied a radi opharmaceutical, technetium-99m (Tc-99m) Infecton, which is based on t he antibiotic ciprofloxacin. Methods We used this agent to image bacte rial infection in 56 patients (one twice) with known or suspected site s of infection. We then compared the imaging results of these patients with those from a radiolabelled leucocyte study. Findings The concord ance rate was 68% (39 out of 57 images). In 18 discordant results Tc-9 9m Infecton was correctly positive in 8 out of 9 positive studies and correctly negative in 4 out of 9 negative studies. 4 out of 5 of the f alsely negative studies were in patients who had taken antibiotics for over 7 days. We found that Tc-99m Infecton gave better imaging result s than radiolabelled leucocytes. Comparison between Tc-99m infecton an d leucocyte imaging gave sensitivities of 84% and 81%, and specificiti es of 96% and 77%, respectively. Interpretation We believe that the sp ecificity Tc-99m Infecton confers for bacterial infection and its ease of administration are the main advantages of this new agent.