PTGS2 and cancer: In this regard, non-invasive imaging of COX-2 in vivo by means of radiolabeled probes for single photon emission computed tomography (SPECT) or positron emission tomography (PET), e.g., by 18F-labeled COX-2 inhibitors, for early diagnosis or therapy monitoring of cancer represents an unmet need [7,8,9,10,11].