MC1R and melanoma: ReCCMSH, which has nanomolar affinity for MC1R, proved increased diagnostic efficacy in melanoma tumors upon labeling with PET isotopes 64Cu and 86Y. Biodistribution studies highlighted that the 86Y-DOTA-ReCCMSH and 64Cu-DOTA-ReCCMSH uptake was two times higher in tumors compared to that of the metabolic agent 18F-FDG.