Peptide imaging with somatostatin analogues: more than cancer probes.

Somastostatin (SS) scintigraphy (SRS) is an effective diagnostic tool for neuroendocrine tumours (NET). High diagnostic accuracy is based on the high affinity binding between SS and its receptors (sstr) expressed both in NET and in some non neoplastic cells. Different SS analogues have been proposed in clinical practice because of the short half-life of the native peptide. Among all synthetic compounds Pentetreotide labelled with In-111 is the most widely used for imaging because of high affinity for sstr 2 and 5. New tracers, showing a different and/or wider affinity, are now available and radio- labelling has been obtained both with gamma and positron emitters. The broader spectrum of interaction with sstr gives a better chance to detect, over NET, other pathological conditions, as chronic inflammation, because of the sstr expression on inflammatory cells, including activated lymphocytes, epithelioid and monocytes.