Preliminary studies of EDDA-tricine-HYNIC-Tyr³-octreotide labelled with technetium-99m: radiopharmaceutical development for the diagnosis of neuroendocrine tumours

The use of labelled molecules with high specificity for an organ or receptor in scintigraphy generates good local images and minimises the exposure of other organs. Octreotide was the first somatostatin synthetic analogue introduced in clinical use in the localisation of tumours with superexpression of somatostatin receptor (sstr). This work studied the labelling of HYNIC-Tyr3-octreotide with 99mTc and the biodistribution of labelled compounds in normal Swiss mice. A high radiochemical yield was obtained when using 20 μg of HYNIC-TOC, 10 mg of EDDA, 20 mg of tricine, 15 μg of SnCl2.2H2O, pH 7.5 and 10 min of boiling water bath. Biodistribution studies showed fast blood clearance of the labelled peptide with high kidney uptake and urinary excretion. The low background in the abdominal region is favourable for the diagnosis of neuroendocrine tumours.