Different Radioactivity Uptake between Somatostatin Analogues Labelled with In-111 and Y-90/88 in Rat Kidney
Abstract
Somatostatin receptor targeting is a valuable method to treat somatostatin receptor-positive tumours. In peptide receptor radionuclide therapy, it is essential to determine the highest activity that can be safely administered to the patient.
As Y-90 emits no gamma rays, absorbed doses for Y-90 are usually estimated using the same peptide labelled with In-111. The aim of the study was to determine if replacement of Y-90/88 by In-111 affects the biodistribution profile of five selected somatostatin analogues in preclinical experiments.
Materials and Methods: Radiolabelled peptides were atministered in to male Wistar rats. Results: The peptides under studs, labelled either with In-111 or with Y-88/90 showed similar distribution profiles in all tissues excepting the kidney.
The kidney radioactivity uptake was significantly lower for Y-88/90-labeled peptide in comparison with the one of In-111. Conclusion: We conclude that a radiation-absorbed dose after Y-90-labelled somatostatin analogues appears to be lower than that predicted by the In-111-labelled peptide.