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Imaging has a key role in tumor response assessment, either in clinical trial or daily practice. The RECIST criteria, based on unidimensional measurement of tumor lesions, are still the most often used in 2018, despite their known limitations, especially since the development of targeted therapies. Other criteria, including the CHOI criteria for GIST evaluation, the modified RECIST criteria (mRECIST) for hepatocellular carcinoma evaluation and the CHUN criteria for colorectal liver metastases evaluation, have been developed and are available alternatives. More recently, the introduction of immunotherapies showed different types of response to this kind of treatment and highlighted the concept of pseudo-progression. In this context, the iRECIST criteria were created. They are used more and more, and they need to be known and applied to avoid missing delayed responses. Finally, functional imaging techniques, such as diffusion- weighted imaging or perfusion imaging, as well as the concept of depth of response and early tumor shrinkage, are imaging tools that are available for tumor evaluation; however, they are still in the research phase. [ABSTRACT FROM AUTHOR]

Stereotactic body radiation therapy takes more and more an important place in the therapeutic arsenal of primitive and secondary liver tumours. The administration of ablative radiation doses can result in specific changes to both the tumour and the healthy hepatic parenchyma, relative to conventional radiation therapy, making the assessment of local changes after stereotactic body radiation therapy, in terms of local control and reaction of healthy tissue, often difficult. It is mandatory to standardize and simplify our evaluation criteria to benefit from a better understanding of the effectiveness of this new treatment modality and allow better reproducibility of available imaging exams. This article presents a literature review of the various radiological changes observed after stereotactic body radiation therapy for liver tumours according to the multiple assessment methods used to determine local control. From the data available, we recommend using modified RECIST criteria proposed by the American Association for the Study of Liver Diseases (AASLD), as objective and relevant criteria of local control after stereotactic body radiation therapy for liver tumours., (Copyright © 2014 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.)