Applications and research progress of PET/CT in dynamic monitoring of immunotherapy in melanoma.

BACKGROUND

Melanoma is a highly aggressive malignancy, and conventional therapies have limited efficacy in metastatic cases. The advent of immune checkpoint inhibitors (ICIs) has significantly improved patient prognosis. However, challenges such as heterogeneous responses, resistance, and immune-related adverse events (irAEs) necessitate reliable tools for early efficacy prediction and dynamic assessment.

MAIN BODY: As a molecular imaging modality that integrates structural and functional information, Positron Emission Tomography/Computed Tomography (PET/CT)-particularly through 18F-fluorodeoxyglucose (18F-FDG) metabolic imaging-can identify atypical response patterns during immunotherapy, including pseudoprogression, hyperprogression, and immune-detached responses (iDRs). It also enables accurate evaluation of therapeutic efficacy using criteria such as PERCIST and PERCIMT. Moreover, PET/CT shows unique value in the early detection of irAEs, with metabolic alterations (e.g., thyroiditis or colitis) preceding clinical symptoms. In recent years, novel probes targeting immune components such as PD-1/PD-L1 and CD8⁺ T cells (Immuno-PET) have further enhanced the capacity for real-time monitoring of the tumor immune microenvironment.

CONCLUSIONS

PET/CT represents a valuable imaging modality for comprehensive assessment of immunotherapy in melanoma. With continued refinement of response criteria and the development of immune-targeted tracers, PET-based imaging is expected to further facilitate personalized and dynamic immunotherapy strategies.