All these compounds displayed high stability in human serum, high binding affinity toward sstR2 that was similar to that of [68Ga|Ga-DOTA-TATE, excretion via the kidneys and high accumulation in tumours with low bone uptake (i.e. low 18F− defluorination) in ex vivo biodistribution studies in tumour-bearing CD1-nu/nu mice. The gene discussed is SSTR2; the disease is neoplasm.