Comparison Between Tc-99m WBC SPECT/CT and MRI for the Diagnosis of Biopsy-proven Diabetic Foot Osteomyelitis

Objective. Magnetic resonance imaging (MRI) is the recommended diagnostic imaging technique for diabetic foot osteomyelitis (DFO), with a reported accuracy of 79%. The gold standard to diagnose osteomyelitis is bone biopsy, with a positive culture and/or histopathology findings consistent with osteomyelitis. The purposes of this study are to assess the accuracy of technetium-99m (Tc-99m) labeled white blood cell (WBC) single-photon emission computed tomography/computed tomography (SPECT/CT) hybrid imaging for diagnosing DFO confirmed by bone biopsy and to compare that to the diagnostic accuracy of an MRI. Materials and Methods. The authors performed a retrospective chart review of 166 patients who received a bone biopsy to confirm the diagnosis of a suspected DFO at a large municipal hospital between 2010 and 2013. Patients were selected on the basis of whether they received an MRI or a SPELT/CT. Patients whose scans were not within a clinically relevant time frame of the biopsy were excluded. Imaging results were correlated with probability of osteomyelitis determined by bone biopsy. Results. For inclusion criteria, 110 patients met the study's Criteria: 52 SPECT/CT patients and 58 MRI patients. The sensitivity, specificity; positive predictive value, and negative predictive value of SPECT/CT were 89%, 35%, 74%, and 60%, respectively;, the corresponding values for MRI were 87%, 37%, 74%, and 58%, respectively. There Were no significant differences in accuracy of diagnosing DFO between imaging techniques. Conclusion: This data suggests that the diagnostic accuracy of SPECT/CT imaging in DFOs is similar to an MRI.