Treatment for brain gliomas is a combined approach of surgery, radiation therapy and chemotherapy. Nevertheless, high-grade gliomas usually recur despite treatment. Ionizing radiation therapy to the central nervous system may cause post-radiation damage. Differentiation between post-irradiation necrosis and recurrent glioma on the basis of clinical signs and symptomatology has not been possible. Computed tomography (CT) and magnetic resonance imaging (MRI) suffer from significant limitations when applied to differentiate recurrent brain tumor from radiation necrosis. We reviewed the contribution of recent MRI techniques, single-photon emission CT and positron emission tomography to discriminate necrosis for glioma recurrence. We concluded that despite the progress being made, further research is needed to establish reliable imaging modalities that distinguish between true tumour progression and treatment-related necrosis.