Post-therapeutical changes in the brain: novel trends in imaging and their infuence on external beam radiotherapy.

UNLABELLED: Presented is the analysis of patients who underwent external beam radiotherapy (EBRT) to the brain in the period from 2003 to 2006 at the department of Radiation Oncology of the St. Elisabeth Cancer Institute. <p align="justify">The aim of our analysis was to identify risk factors of late delayed therapy induced injuries (LDTI) in the brain. The patients were regularly examined with magnetic resonance (MRI), including conventional and advanced techniques: perfusion imaging (pMRI), diffusion weighted imaging (DWI), MRI spectroscopy (MRS). The results from MRI were correlated with ¹⁸fluoro-deoxyglucose positron emission tomography (¹⁸FDG/PET) scans, as none of the listed method is sufficiently sensitive and specific by itself. Also clinical data records and treatment plans of these patients were analyzed. </p><p align="justify">In our cohort we found 6 patients with abnormal post-therapeutical changes, 4 of them with MR and ¹⁸FDG/PET scans characteristics for LDTI - radiation necrosis. In one patient biopsy was performed and radiation necrosis (RN) was confirmed. </p> KEYWORDS: radiation necrosis, MRI, PET, 3D conformal radiotherapy (3D-CRT).