Immunotherapy is an anti-tumor response based on the autoimmune system and has changed the treatment landscape of many cancers. However

the mechanism of immune checkpoint inhibitor (ICI) is complex

and delayed response

pseudo-progression

hyper-progression

and even immune-related adverse events often occur in tumor patients. Although the new version of immune response evaluation criteria in solid tumor (iRECIST) is applied to tumor immunotherapy

the traditional i

mage-based solid tumor efficacy evaluation criteria have some limitations and evaluation blind spots.

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F-FDG positron emission tomography (PET)/computed tomography (CT) has a potential role in assessing treatment response and predicting prognosis. New radiopharmaceuticals such as targeting immune checkpoints such as programmed death ligand 1 (PD-L1) and CD8

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T cell imaging also provide a unique opportunity to define the tumor immune microenvironment to better monitor immune efficacy in patients. This article reviewed current concepts of immunotherapy response assessment

current oncology applications and imaging needs of cancer immunotherapy. And the use of FDG PET/CT in immunotherapy surveillance and emerging non-FDG PET imaging radiometric tracers for cancer immunotherapy imaging were also discussed

aiming to describe future trends in molecular imaging in the field of immunotherapy.