Pseudoprogression in Gliomas: the Use of Advanced MRI for Treatment Decisions

Purpose of review: The definitions of pseudoprogression (PsP) have greatly varied with time, with a reported incidence ranging from 10 to 30%. PsP is mainly a radiological definition, as a new or enlarging area of contrast agent enhancement, without argument of true tumor progression (TP), which will resolve or stabilize without any change in treatment. Because anatomical magnetic resonance imaging (MRI) is unsatisfactory in differentiating PsP from TP, advanced MR techniques are needed, adding sensitivity and specificity to obtain a more solid diagnosis. Recent findings: Because of its high reported diagnostic accuracy, perfusion MR seems to be the most reliable technique to better identify PsP, the lack of standardization of MR spectroscopy compromising its availability in daily practice. Summary: A multi-modal and dynamic MR approach is recommended, after harmonization of image acquisition and post-processing. Due to the recent interest of immunotherapies, identifying PsP will continue to be an issue, particularly in better including true progressing patients in clinical trials.