A compound comprising a pyridine carboxamide structure wherein an aromatic ring in the structure is substituted radio halogen atom 18F (fluorine) and wherein the substitution on the amide nitrogen atom is: a hydrogen atom and a tertiary aminoalkyl group or such that the amide nitrogen is a member of a saturated ring structure having a second nitrogen atom in the ring or a pharmaceutically acceptable salt of said compound. A structural representation of a possible compound is shown in formula (I). R3 and R4 can form an aryl ring fused to the pyridine ring. Also disclosed is a process for making a compound comprising the step of treating a precursor comprising a leaving group so as to replace said leaving group with the radiohalogen atom18F, said precursor comprising a pyridine carboxamide structure wherein an aromatic ring in the structure is substituted with said leaving group and wherein the substitution on the amide nitrogen atom is a hydrogen atom and a tertiary aminoalkyl group or the process includes the step of treating a solution of a precursor comprising a chloro leaving group in dimethylformamide with K[18F]-K2.2.2 K2CO3, and heating the mixture at 150 degrees C for 10 minutes said precursor comprising a pyridine carboxamide structure wherein an aromatic ring in the structure is substituted with said leaving group and wherein the substitution on the amide nitrogen atom is a hydrogen atom and a tertiary aminoalkyl group, such that the compound binds to melanin.
