New enhancing lesions after surgery and chemoradiation for high grade glioma commonly contain variable proportions of tumor recurrence (TR), tissue necrosis and treatment related changes. Our purpose is to determine whether the pattern of contrast enhancement and perfusion MR parameters correlate with the percentage of TR in these lesions. Methods: We prospectively enrolled 30 patients with high grade gliomas who presented with a new enhancing lesion suspicious for tumor recurrence. Each patient underwent conventional MRI with DCE and DSC perfusion MRI. The pattern of enhancement was classified by a blinded neuroradiologist in 5 different categories (solid, focal nodular, peripheral rim, hazy, punctate). A hot spot region-of-interest analysis was performed for each parametric map (Ktrans, AUC, Vp, corrected CBV). TR percentage was defined histopathologically. The lesions were categorized into predominant TR (=tumor>70%), predominant treatment related changes (T=<35%) and mixed lesions (35 %< T=<70%). Differences between the groups were assessed via Kruskal-Wallis and Mann-Whitney U tests. Results: There were 32 lesions (4 predominantly treatment related lesions,5 mixed lesions,23 predominant tumor recurrence). There is no significant difference in the enhancement pattern between the three groups (p=0.18).Statistically significant difference was only seen for corrected CBV between the three groups (p=0.01), mainly between the mixed and predominant tumor groups. The rest of the perfusion parameters did not show a statistically significant difference between the groups(p>0.05). Conclusion: Corrected CBV might be useful in predicting the proportion of tumor recurrence in post-treatment high grade gliomas.