MR Imaging of Neoplastic Central Nervous System Lesions: Review and Recommendations for Current Practice

Abstract

SUMMARY: MR imaging is the preferred technique for the diagnosis, treatment planning, and monitoring of patients with neoplastic CNS lesions. Conventional MR imaging, with gadolinium-based contrast enhancement, is increasingly combined with advanced, functional MR imaging techniques to offer morphologic, metabolic, and physiologic information. This article provides updated recommendations to neuroradiologists, neuro-oncologists, neurosurgeons, and radiation oncologists on the practical applications of MR imaging of neoplastic CNS lesions in adults, with particular focus on gliomas, based on a review of the clinical trial evidence and personal experiences shared at a recent international meeting of experts in neuroradiology, neuro-oncology, neurosurgery, and radio-oncology.ABBREVIATIONS: ADC ϭ apparent diffusion coefficient; CBV ϭ cerebral blood volume; CNS ϭ central nervous system; DCE ϭ dynamic contrast-enhanced; DSC ϭ dynamic susceptibility contrast; DTI ϭ diffusion tensor imaging; DWI ϭ diffusion-weighted imaging; FLAIR ϭ fluid-attenuated inversion recovery; FSE ϭ fast spin-echo; GFR ϭ glomerular filtration rate; GRE ϭ gradient recalled-echo; K trans ϭ volume transfer coefficient; MRS ϭ MR spectroscopy; PET ϭ positronemission tomography; PWI ϭ perfusion-weighted imaging; rCBV ϭ relative cerebral blood volume; TSE ϭ turbo spin-echo N eoplastic CNS lesions are a heterogeneous group of diseases with a variable outcome that reflects the precision of diagnosis and the delivery of optimal and specific treatment. CNS imaging has a pivotal role in directing management decisions.The goals and requirements for CNS imaging are multiple and include the establishment of a diagnosis and differential diagnosis, with accurate lesion grading for characterization of tumor biology. Imaging is an essential part of the decisionmaking process for therapy and later for planning of surgical or radiotherapeutic interventions. In the case of neurosurgery, neuroimaging can precisely define the location and accurately delineate the lesion and its relationship to eloquent gray-and white-matter structures, before intervention. In radiation therapy, imaging can define and demarcate margins for therapy planning. Imaging is mandatory after therapeutic intervention for monitoring disease and possible side effects.MR imaging is the standard technique for visualizing and characterizing neoplastic CNS lesions, with superior sensitivity compared with alternative modalities.1-4 Diagnosis and treatment planning are routinely based on conventional MR imaging, such as T2-weighted imaging, FLAIR, and T1 unenhanced FSE or GRE. Following contrast-enhanced T1-weighted imaging, sequences including 3D GRE or 2D TSE or FSE are used routinely for assessment of brain tumors. Through enhancing tissue relaxation, gadolinium-based contrast media improve the sensitivity and specificity of conventional and perfusion-weighted MR imaging examinations, with the capability to identify lesions not visible on unenhanced MR imaging and to provide additional information o...

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