The role of imaging in the evaluation of tumor response is expanding rapidly. The current response evaluation criteria in solid tumors (RECIST) based on anatomical changes suffers from many limitations related mainly to the inter- and intra-observer variability to delineate the tumoral edges. Consequently, there is a need to update and integrate the RECIST criteria beyond the classical anatomical changes with other more sophisticated methods using three-dimensional and functional criteria. The goal of this paper is to review the current criteria of RECIST measurements (RECIST 1.1) with their limitations and to evaluate the emerging solutions available with the new imaging techniques like PET-CT.