Distinguishing glioma recurrence from treatment effect after radiochemotherapy and immunotherapy

Recent advancements have made radiation and chemotherapy the standard of care for newly diagnosed glioblastomas. The use of these therapies has resulted in an increased diagnosis of pseudoprogression and radiation-induced necrosis. Standard MRI techniques are inadequate in differentiating tumor recurrence from posttreatment effects. Diagnosis of a posttreatment lesion as glioma recurrence rather than radiochemotherapy or immunotherapy treatment effect is critical. This increase in accuracy plays a role as newer immunotherapies incurring posttreatment effects on MRI emerge. Advancements with magnetic resonance spectroscopy, diffusion-weighted imaging, and functional positron emission tomography scans have shown promising capabilities. Further investigations are necessary to assess the imaging algorithms and accuracy of these modalities to differentiate true glioma recurrence from radiotherapy or immunotherapy treatment effect.