Dynamic contrast-enhanced magnetic resonance imaging can assess vascularity within fracture non-unions and predicts good outcome.

ABSTRACT

OBJECTIVES: To prospectively evaluate whether dynamic contrast-enhanced (DCE) MRI can assess vascularity within non-unions and predicts clinical outcome in combination with the clinical Non-Union Scoring System (NUSS). METHODS: Fifty-eight patients with non-unions of extremities on CT underwent 3-T DCE MRI. Signal intensity curves obtained from a region-of-interest analysis were subdivided into those with more intense contrast agent uptake within the non-union than in adjacent muscle (vascularised non-union) and those with similar or less contrast uptake. The pharmacokinetic parameters of the Tofts model K trans, K ep, iAUC and V e were correlated with union at CT 1 year later (n = 49). RESULTS: Despite inserted osteosynthetic material, DCE parameters could be evaluated in 57 fractures. The sensitivity/specificity of vascularised non-unions as an indicator of good outcome was 83.9%/50.0 % compared to 96.8%/33.3% using NUSS (n = 49). Logistic regression revealed a significant impact of NUSS on outcome (P = 0.04, odds ratio = 0.93). At first examination, median iAUC (initial area under the enhancement curve) for the ratio non-union/muscle was 10.28 in patients with good outcome compared with 3.77 in non-responders (P = 0.023). K trans, K ep and Ve within the non-union were not significantly different initially (n = 57) or 1 year later (n = 19). CONCLUSIONS: DCE MRI can assess vascularity in fracture non-unions. A vascularised non-union correlates with good outcome. KEY POINTS • Dynamic contrast-enhanced magnetic resonance imaging can assess vascularity within bony non-unions. • Vascularised ununited fractures appear better at 1-year CT than poorly vascularised fractures. • Non-union healing after osteosynthesis or osteoinductive drugs fundamentally requires vascularity. • DCE MRI predicts treatment outcome better than the clinical Non-Union Scoring System. • DCE MRI is clinically feasible to predict treatment outcome in bony non-unions.