Seminars in radiation oncology
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In recent years, the management of glioma has evolved significantly, reflecting our better understanding of the underlying mechanisms of tumor development, tumor progression, and treatment response. Glioma grade, along with a number of underlying molecular and genetic biomarkers, has been recognized as an important prognostic and predictive factor that can help guide the management of patients. This article highlights advances in magnetic resonance imaging (MRI), including diffusion-weighted imaging, diffusion tensor imaging, magnetic resonance spectroscopy, dynamic contrast-enhanced imaging, and perfusion MRI, as well as position emission tomography using various tracers including methyl-(11)C-l-methionine and O-(2-(18)F-fluoroethyl)-l-tyrosine. Use of multiparametric imaging data has improved the diagnostic strength of imaging, introduced the potential to noninvasively interrogate underlying molecular features of low-grade glioma and to guide local therapies such as surgery and radiotherapy.
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Following combined-modality therapy for the treatment of low-grade gliomas, the assessment of treatment response and the evaluation of disease progression are uniformly challenging. In this article, we review existing response criteria, and discuss the limitations of conventional magnetic resonance imaging to distinguish between progression and treatment effect. We review the data on advanced imaging techniques including positron emission tomography and functional magnetic resonance imaging, which may enhance the interpretation of posttreatment changes, and enable the earlier assessment of the efficacy and toxicity of therapy in these patients with prolonged survival.