Dynamic Contrast-Enhanced Sonography and Dynamic Contrast-Enhanced Magnetic Resonance Imaging for Preoperative Diagnosis of Infected Nonunions

Bone regeneration depends on perfusion of the fracture tissue, whereby hypervascularityis associated with infection, which itself causes nonunions. To date, nonunionperfusion has not been assessed with contrast- enhancedsonography. The aim of this study was to evaluate the potential of contrast- enhancedsonography in the analysis of nonuniontissue perfusion.Nonunion vascularity of 31 patients before revision surgery was prospectively examined with qualitative contrast- enhancedsonography and dynamic contrast- enhancedmagnetic resonance imaging (MRI). Time-intensity curves from 2-minute contrast- enhancedsonographic video clips were generated, and parameters such as wash-in rate, rise time, and peak enhancementwere quantified. On dynamic contrast-enhanced MRI, the initial area under the enhancementcurve was quantified. Preoperative radiographs, computed tomograms, the clinical nonunionscore, laboratory infection features, as well as contrast- enhancedsonographic and dynamic contrast-enhanced MRIperfusion were correlated with microbiologicalresults from the nonuniontissue.Both qualitative and quantitative contrast- enhancedsonography showed significant differences between infected and aseptic nonunions(P = .015 and .020). The qualitative dynamic contrast-enhanced MRIanalysis was not significant (P= .244), but after quantification, a strong correlation (P = .007) with microbiologicalresults was noted. A receiver operating characteristic analysis calculated ideal cutoff values for quantitative contrast- enhancedsonography and dynamic contrast-enhanced MRIso that their combination detected infected nonunionswith sensitivity and specificity of 88.9% and 77.3%, respectively. Clinical, radiologic, and laboratory examinations did not correlate with microbiologicalresults (P > .05).Contrast- enhancedsonography can visualize the vascularity of nonunionsin real time, while quantification software allows for a semiobjective evaluation of bone perfusion. The correlations of both quantitative contrast- enhancedsonography and dynamic contrast-enhanced MRIwith microbiologicalresults show their high value for differentiation of infected from aseptic nonunions.