The efficacy of technetium-99m ciprofloxacin (Infecton) imaging in suspected orthopaedic infection: a comparison with sequential bone/gallium imaging

Technetium-99m ciprofloxacin (Infecton) has recently become established as a new radiopharmaceutical for the imaging of infection. This study was performed to determine the value of Infecton imaging in demonstrating orthopaedic infection and to compare the results with bone/gallium imaging. Twenty-two patients (12 female, 10 male; mean age 51.7+/-16.8 years) with suspected orthopaedic infective conditions were included in the study. The patients underwent three scintigraphic studies in the following sequence: 740 MBq 99mTc-methylene diphosphonate (MDP) three-phase bone scintigraphy; at least 2 days later, 370 MBq Infecton scan at 1-4 h; and finally, 185 MBq gallium-67 scintigraphy. 67Ga imaging could not be performed on four patients. All images were blindly interpreted by two independent observers. The final diagnosis was made by consensus when the readings were different. Interpretation of the early and late Infecton images was made separately, with visual findings being classified according to a four-grade scale (0, +, ++, +++). Images graded 0 and +, and also those regions which showed a decrease in uptake grade on late images as compared with early images, were classified as negative for infection; grades ++ and +++ were classified as positive. Bone/gallium images were considered positive when the images were spatially incongruent or when gallium uptake was more intense than that of 99mTc-MDP. The diagnosis was confirmed by intraoperative microbiological or histological findings, or by the presence of gross purulence. The sensitivity of Infecton imaging was found to be 85%, the specificity 92% and the accuracy 88%, as compared to figures of 78%, 100% and 90%, respectively, for bone/gallium imaging. Although the two modalities showed a similar clinical yield, the easy availability of Infecton and the short investigation time make Infecton imaging the better option for the detection of orthopaedic infection.