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

OBJECTIVES: Bone regeneration depends on perfusion of the fracture tissue, whereby hypervascularity is associated with infection, which itself causes nonunions. To date, nonunion perfusion has not been assessed with contrast-enhanced sonography. The aim of this study was to evaluate the potential of contrast-enhanced sonography in the analysis of nonunion tissue perfusion.

METHODS: Nonunion vascularity of 31 patients before revision surgery was prospectively examined with qualitative contrast-enhanced sonography and dynamic contrast-enhanced magnetic resonance imaging (MRI). Time-intensity curves from 2-minute contrast-enhanced sonographic video clips were generated, and parameters such as wash-in rate, rise time, and peak enhancement were quantified. On dynamic contrast-enhanced MRI, the initial area under the enhancement curve was quantified. Preoperative radiographs, computed tomograms, the clinical nonunion score, laboratory infection features, as well as contrast-enhanced sonographic and dynamic contrast-enhanced MRI perfusion were correlated with microbiological results from the nonunion tissue.

RESULTS: Both qualitative and quantitative contrast-enhanced sonography showed significant differences between infected and aseptic nonunions (P = .015 and .020). The qualitative dynamic contrast-enhanced MRI analysis was not significant (P= .244), but after quantification, a strong correlation (P = .007) with microbiological results was noted. A receiver operating characteristic analysis calculated ideal cutoff values for quantitative contrast-enhanced sonography and dynamic contrast-enhanced MRI so that their combination detected infected nonunions with sensitivity and specificity of 88.9% and 77.3%, respectively. Clinical, radiologic, and laboratory examinations did not correlate with microbiological results (P > .05).

CONCLUSIONS: Contrast-enhanced sonography can visualize the vascularity of nonunions in real time, while quantification software allows for a semiobjective evaluation of bone perfusion. The correlations of both quantitative contrast-enhanced sonography and dynamic contrast-enhanced MRI with microbiological results show their high value for differentiation of infected from aseptic nonunions.