[Nuclear medicine approach for the detection and characterization of liver metastasis]

Nuclear Medicine procedures include in vitro techniques able to detect and characterize liver metastases. Among the in vitro applications, circulating tumour markers level determination provides information about the response to therapy and the presence of active disease. While after a successful antineoplastic treatment the serum biological marker level usually falls, a progressive increase represents an alarm signal of occult/residual tumour or metastatic dissemination. However, this method is not able to identify the site of the lesion, therefore complementary imaging techniques are needed to confirm or exclude the diagnostic suspicion. The main advantages of the in vitro methods are the low cost and, consequently, the possibility of periodically checking of tumour activity. The in vivo nuclear medicine techniques are usually performed as second level test. In fact, they can play a role in detecting and characterizing hepatic metastases when radiological methods are inconclusive or when selected tumour seeking agents (i.e. radiolabelled antibodies, radioiodinated mIBG, Octreotide, etc.) can be used. Moreover, the introduction of PET procedures has provided physicians with a useful tool for the evaluation of tumour behaviour (glucose consumption, proteic, synthesis, receptor expression). A further significant diagnostic improvement is represented by the recent introduction of the multimodality co-registration of images (including CT scan, MRI, SPET, PET). The fusion imaging allows a superimposition of the functional and metabolic information to the morphological one.