For submission to Journal of Labelled Compounds and Radiopharmaceuticals Imaging COX-2 expression in cancer using PET/SPECT radioligands: Current status and future directions Short title:- PET/SPECT imaging of COX-2 expression

The role of COX-2 as a driving force in early tumourigenesis and the current interest in the combination of COX-2 inhibitors with standard therapy in clinical trials creates an urgent need to establish clinically relevant diagnostic tests for COX-2 expression. Molecular imaging using small molecule probes radiolabelled for both PET and SPECT offer the potential to meet this need, providing a minimally invasive readout for the whole disease burden. This review summarises current approaches to the radiolabelling of small molecule COX-2 inhibitors and their analogues for PET and SPECT imaging, and gives an overview of their biological evaluation and likely success of clinical application.