Comparison of 99mTc ciprofloxacin, 99mTc white blood cell and three-phase bone imaging in the diagnosis of hip prosthesis infections:: improved diagnostic accuracy with extended imaging time

The purpose of this study was to compare the utility of Tc-99m labelled ciprofloxacin (Infecton) imaging with the Tc-99m white blood cell and three-phase bone imaging procedures for identifying hip prosthesis infection. We studied 30 symptomatic patients in whom infection was confirmed in eight and excluded in 22 cases based on clinical and microbiological findings, (99)mTc ciprofloxacin images were obtained at 1, 4 and 24 h after the injection of the tracer, and the data were compared to those obtained from Tc-99m leukocyte and three-phase bone imaging. The Tc-99m ciprofloxacin imaging correctly identified all true infections. In 13 (59%) of the noninfected patients, non-specific uptake of Tc-99m ciprofloxacin was found in the 1-h and 4-h images, which disappeared, however, in the 24-h images. When the early and late Tc-99m ciprofloxacin images were compared, the specificity was found to improve from 41% to 95%, positive predictive value from 38% to 89%, and the diagnostic accuracy from 57% to 97%. The accuracy of the conventional Tc-99m leukocyte imaging was 90%. Dynamic bone imaging also yielded abnormal findings in all the infected patients although also in 23% of the non-infected patients. Current data indicate that Tc-99m ciprofloxacin is a useful method for confirming hip prosthesis infection. The diagnostic efficiency of this method is improved when the imaging time is extended to 24 h post-injection of the tracer. ((C) 2002 Lippincott Williams Wilkins).