Purpose: To describe and correlate with radiation therapy the occurrence of cerebral radiation necrosis in patients irradiated for nasopharyngeal or ethmoidal tumor. Materials and Methods. From 1986 to 1998, 1 201 patients, 981 with nasopharyngeal tumors, and 220 with ethmoidal tumors were treated by radiotherapy. Twenty eight developed cerebral necrosis. MRI were performed in all patients and CT in 18 patients. Diagnosis was considered at imaging, and confirmed by follow-up.
Results: The incidence of cerebral radionecrosis was 2.33%. The time interval between treatment and necrosis ranged from 2 months to 9 years. CT showed edema and/or focal enhancement in all cases except for 4 patients with normal CT examinations. MRI showed edema and/or abnormal focal punctate or gyriform enhancement in all patients. Lesions were localized in the temporal lobe (n=18), frontal lobe (n=9), pons (n=3) and optic nerve (n=2). The doses related to the areas of necrosis ranged from 13 to 135Gy. In 2 cases necrosis was situated at the boundaries of the radiation field. Imaging follow-up showed complete (n=3) or incomplete remission (n=1), lesion progression (n=11), cerebral atrophy (n=5) and stability (n=7).
Conclusion: MRI is useful to diagnose cerebral necrosis. New technologies may reduce the incidence of this complication.