[Pseudoprogression or pseudoresponse: a challenge for the diagnostic imaging in Glioblastoma multiforme].

This methodological paper on magnetic resonance tomography imaging recalls the assessment criteria on therapy response of Glioblastoma multiforme as defined by David Macdonald in 1990 that have remained State of the Art since their first publication. It defines the terms "pseudoprogression", "radiation induced necrosis" and "pseudoresponse". These phenomena are seen increasingly since the introduction of radiochemotherapy with Temozolomide as treatment standard in glioblastoma and since the use of antiangiogenetic therapy in malignant gliomas. Therefore, the assessment criteria have been recently updated with the newly proposed "RANO criteria (Response assessment in Neuro-Oncology)". Furthermore, the potential of additional information to conventional MR by MR perfusion, MR diffusion and MR spectroscopy is briefly discussed.