Review of WHO 2016 Changes to Classification of Gliomas; Incorporation of Molecular Markers

In 2016, the World Health Organization (WHO) updated its brain tumor classification system to recognize the importance of key genetic alterations in glioma, incorporating these features into the definitions of a variety of brain tumors for the first time. Several of these genetic alterations, such as IDH mutation and 1p/19q codeletion, can be assessed at imaging, with approaches including visual inspection, advanced MR and PET techniques, and machine learning reported in the literature. Reliable noninvasive assessment of these genetic features by imaging may allow for improved treatment planning and patient counseling, and an understanding of how the various genetically defined tumor types respond to therapy is useful in interpretation of post-treatment imaging. In the future, the importance of genetic features in glioma diagnosis and treatment will only increase, and it is incumbent upon neuroradiologists to stay abreast of these developments in order to provide optimal patient care.