B-0188 Dynamic contrast-enhanced MRI can assess vascularity within pseudarthrotic clefts and predicts good clinical outcome

M.-A. Weber, K. Bloess, I. Burkholder, D. Bender, G. Schmidmaier, H.-U. Kauczor, O. Schoierer | Thursday, March 7, 14:00 – 15:30 / Room E1

Purpose: To prospectively evaluate whether dynamic contrast-enhanced (DCE) MRI can assess vascularity within pseudarthrotic clefts and predicts clinical outcome better than the clinical non-union scoring system (NUSS).
Methods and Materials: Sixty-four patients (mean age, 49.3 years) with non-union of an extremity fracture in computed-tomography received 3-Tesla MRI including DCE (coronal T1-weighted fat-saturated VIBE, TR/TE=3.76/1.35ms, 17 measurements, 2 mm slice thickness) after 0.1mmol/kg body-weight of gadoterat. We assessed vascularity within the pseudarthrotic cleft using a region-of-interest analysis. Signal intensity curves were subdivided into those with more intense contrast-agent uptake in the pseudarthrotic cleft than in normal adjacent muscle tissue (vascularised non-union) and those with similar or less uptake. The pharmacokinetic parameters of the Tofts model (K_trans, K_ep, iAUC, V_e) were correlated to the clinical outcome at one-year follow-up (n=37).
Results: Despite inserted osteosynthesis material, DCE parameters could be evaluated in n=60 at first visit. Sensitivity/specificity of vascularised non-unions as indicator of good clinical outcome was 77.3%/46.7% compared to 95.5%/26.7% using NUSS. Logistic regression revealed non-significant impact of NUSS on clinical outcome (p=0.27, odds ratio=0.97). At first examination, median iAUC (initial area under the enhancement curve) was 24.13 in patients with good outcome compared with 10.96 in non-responders (p=0.032), while K_trans, K_ep, and V_e were not significantly different. Using a receiver operating characteristic analysis, sensitivity/specificity of iAUC at the optimal cut-off value of 17.5 to predict outcome was 68.2%/76.9%. All pharmacokinetic parameters did not change significantly at the one-year control (n=18).
Conclusion: DCE MRI can assess vascularity in pseudarthrotic clefts. A vascularised non-union indicates good clinical outcome.

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