Objective: To investigate the diagnostic efficacy of indigenously developed single vial kit preparation of Tc-ciprofloxacin (Diagnobact) for the detection of orthopedic infections.
Methods: Seventy-seven patients [25 with clinical suspicion of diabetic foot osteomyelitis (DFOM), 25 with orthopedic device-related infection (ODRI) and 27 with tubercular bone infection] underwent three-phase Tc-methylenediphosphonate bone scintigraphy followed by static Tc-ciprofloxacin imaging at 1, 4 and 24 h. Imaging (anterior and posterior views) was performed under a dual-head gamma-camera using a low-energy, high-resolution, parallel-hole collimator. The lesion-to-background ratio (LBR) of the radiotracer was calculated on the static isotime Tc-ciprofloxacin images using semiquantitative analysis. Scintigraphic (Diagnobact) results were compared with the histopathological and/or culture/PCR analysis as a gold standard.
Results: The mean LBR of the radiotracer (Tc-ciprofloxacin) in the positive scans (n=29; 16 ODRI, 13 DFOM) was > or =2.0 at 1 h postinjection and remained consistent till 24 h. In contrast, the mean LBR in the negative scans (n=21; 12 DFOM, nine ODRI) was < or =1.5 at 1 h and declined significantly (P<0.05) at 24 h. The observed trend in the mean LBR in positive (n=18) and negative (n=9) scans for tubercular osteomyelitis was identical to that seen in the nontubercular bacterial infections.
Conclusion: The management protocol for patients with suspected bony infection may include a three-phase bone scan followed by Tc-ciprofloxacin scan. An LBR of > or =2.0 at 1 h that remained consistent till 24 h on Tc-ciprofloxacin scan is indicative of active bacterial infection. However, resistance to ciprofloxacin at the bacterial cell membrane may be a limitation of this technique.