MRS, perfusion MRI separate radiation necrosis from tumor

Increasingly aggressive treatment protocols are being used in the hope of improving patient survival rates. These regimens, however, can lead to a wide spectrum of complications owing to the overlap between “effective” and “neurotoxic” doses of radiation. Differentiating tumor recurrence from treatmentinduced change is a clinical and radiological challenge. Researchers have suggested three mechanisms to explain radiationinduced neurotoxic effects in the brain: • Direct cellular damage. Radiation generates reactive oxygen species that damage cellular DNA, eventually leading to the induction of cellular apoptosis. Tumor cells with a high mitotic rate are affected the most because they are less able than normal cells to instigate DNA repair.