Tc-99m ciprofloxacin scintigraphy in evaluation of orthopedic infections

Identification of bacterial infection in orthopedic practice is an important issue for appropriate management. Conventional radiography including CT examination has limited role in such a situation. A Tc-99m Ciprofloxacin has been developed to localize bacterial infection in order to differentiate infection from inflammation. Critical evaluation of role of Tc-99m Ciprofloxacin scintigraphy in orthopedic practice was done in the present study. 104 patients with suspected infection in orthopedic clinic were taken up for Tc-99m Ciprofloxacin scintigraphy. A dose of 370 MBq of Tc-99m Ciprofloxacin was injected intravenously. Imaging was performed using Siemens integrated DIACAM camera with low energy all parallel or high-resolution collimators. Multiple spot views at serial time (1 hour, 4 hours and 24 hours) were obtained in 256 x 256 matrix size in ICON computer. Focal area of abnormal radionuclide concentration, which increased with time, was considered to be the pattern suggestive of presence of infection. In cases of equivocal qualitative appearance, quantitation of uptake was ascertained by the count statistics obtained using region of interest program. Final diagnosis of sepsis was based on microbiological examination or evidence of beneficial response to antibiotic therapy. Tc-99 Ciprofloxacin scintigraphy showed most favourable results in peripheral tubercular as well as non-tubercular osteomyelitis, tubercular arthritis and in cases with prosthesis (including vascular stent). It showed limited role in Pott's spine. The best sensitivity, specificity and accuracy of Tc-99m Ciprofloxacin using the defined criteria was 90%, 84% and 88% respectively in cases with non-tubercular osteomyelitis. Serial imaging up to 24 hours was required in ∼ 70% of cases. In ∼ 30% of cases quantification was required to form an opinion. We conclude that Tc-99m Ciprofloxacin is a highly useful technique in the management of infection in orthopedic practice. The procedure should include serial delayed imaging up to 24 hrs after administration of radiopharmaceutical and quantitative analysis should be undertaken in cases of equivocal qualitative images