OBJECTIVETo review the applications of magnetic resonance imaging (MRI) techniques in assessing treatment response to gamma knife radiosurgery for brain tumors.

DATA SOURCESPublished articles about assessing treatment response to gamma knife radiosurgery for brain tumors were selected using PubMed. The search terms were "MRI", "gamma knife" and "brain tumors".

STUDY SELECTIONArticles regarding the MRI techniques using for early assessment of treatment response of gamma knife were selected.

RESULTSMRI techniques, especially diffusion weighted imaging, perfusion weighted imaging, magnetic resonance spectroscopy, are useful for early assessment of treatment response of gamma knife by detecting the hemodynamic, metabolic, and cellular alterations. Moreover, they can also provide important information on prognosis.

CONCLUSIONSDiffusion weighted imaging, perfusion weighted imaging and magnetic resonance spectroscopy can provide early assessment of treatment response of gamma knife for brain tumors, and also information of tumor progression or recurrence earlier than conventional MRI. But there are still many questions to be answered which should be based on the development and advancement of MRI and related disciplines.