Distinguishing recurrent high-grade gliomas from radiation injury: a pilot study using dynamic contrast-enhanced MR imaging

Rationale and objectives: The accurate delineation of tumor recurrence and its differentiation from radiation injury in the follow-up of adjuvantly treated high-grade gliomas presents a significant problem in neuro-oncology. The aim of this study was to investigate whether hemodynamic parameters derived from dynamic contrast-enhanced (DCE) T1-weighted magnetic resonance imaging (MRI) can be used to distinguish recurrent gliomas from radiation necrosis.

Materials and methods: Eighteen patients who were being treated for glial neoplasms underwent prospectively conventional and DCE-MRI using a 3T scanner. The pharmacokinetic modelling was based on a two-compartment model that allows for the calculation of K(trans) (transfer constant between intra- and extravascular, extracellular space), v(e) (extravascular, extracellular space), k(ep) (transfer constant from the extracellular, extravascular space into the plasma), and iAUC (initial area under the signal intensity-time curve). Regions of interest (ROIs) were drawn around the entire recurrence-suspected contrast-enhanced region. A definitive diagnosis was established at subsequent surgical resection or clinicoradiologic follow-up. The hemodynamic parameters in the contralateral normal white matter, the radiation injury sites, and the tumor recurrent lesions were compared using nonparametric tests.

Results: The K(trans), v(e), k(ep), and iAUC values in the normal white matter were significantly different than those in the radiation necrosis and recurrent gliomas (0.01, <P < .0001). The only significantly different hemodynamic parameter between the recurrent tumor lesions and the radiation-induced necrotic sites were K(trans) and iAUC, which were significantly higher in the recurrent glioma group than in the radiation necrosis group (P ≤ .0184). A K(trans) cutoff value higher than 0.19 showed 100% sensitivity and 83% specificity for detecting the recurrent gliomas, whereas an iAUC cutoff value higher than 15.35 had 71% sensitivity and 71% specificity. The v(e) and k(ep) values in recurrent tumors were not significantly higher than those in radiation-induced necrotic lesions.

Conclusions: These findings suggest that DCE-MRI may be used to distinguish between recurrent gliomas and radiation injury and thus, assist in follow-up patient management strategy.