ABSTRACT
Immunotherapy has entered the clinical treatment for various tumors, among which the blockade therapy of PD-1/PD-L1 immune checkpoint is currently the most important tumor immunotherapy method. At present, immunohistochemical method are used in clinical practice to detect PD-L1 expression in tumor patients and screen for indications. However, this method is constrained by factors such as heterogeneity, dynamic changes in PD-L1 expression, and limited sample collection. PD-(L)1 PET imaging utilizes radiolabeled molecules to non-invasively assess PD-(L)1 expression in space and time, and complementary use with IHC has theoretically incomparable advantages. This article reviews the latest progress in the PD-(L)1 probe molecular imaging principles, clinical research and existing problems.