Prospects for Cancer Diagnosis, Treatment, and Surveillance: [18F]FDG PET/CT and Innovative Molecular Imaging to Direct Immunotherapy in Cancer

Positron Emission Tomography (PET), a noninvasive technique, is most suitable for quantitative evaluation of in vivo tumor biology. Based on its metabolic activity, the accumulation of F-18 fluorodeoxyglucose ([18F]FDG), a positron emitter radionuclide, is most explored indicative of tumor features. Quantitative evaluation of FDG uptake is frequently used for treatment monitoring following chemotherapy or chemoradiotherapy. Several investigations showed that FDG PET, which measures metabolic change, was a more sensitive marker than CT or MRI, which measures morphological change. [18F]FDG is now frequently used to assess tumor metabolism as well as to track the effectiveness of immunotherapy, which is a useful treatment for several malignancies. With the use of in vivo whole-body CD8+ T cell and PD-L1 expression imaging, for instance, radiopharmaceuticals that are novel in nature offer the rare chance to characterize the immunological tumor microenvironment (TME) and more accurately forecast which patients may react to therapy. Longitudinal molecular imaging may also aid in clarifying potent changes, especially in instances of resistance that occurred during immunotherapy, and aid in guiding a more individualized therapeutic strategy. To categorize, forecast, and track treatment response and molecular dynamics in areas of therapeutic need, this review focuses on new and existing uses of [18F]FDG for imaging.