The purpose of this multicenter study is to assess a diagnostic strategy concerning
differential diagnosis between radiation necrosis and relapse in brain metastases treated
with radiosurgery. Two non-invasive tests - positron emission tomography (PET) with
1F-fluoro-ethyl-tyrosine (FET) and magnetic resonance spectroscopy (MRS) - will be compared
to histology in a cohort of patients presenting growing lesions 6 months after radiosurgical
The results of this study should help to earlier diagnosis of recurrences after radiosurgery
and to perform an appropriate treatment for patients.