Advances in Molecular Imaging for Neuroendocrine Neoplasms

Neuroendocrine neoplasms (NENs) represent a heterogenous group of tumors with significant inter- and intra-patient variability. Once considered to be rare, neuroendocrine neoplasms are being increasingly recognized through the advent of advanced diagnostic techniques, which may be contributing to the significant increase in the incidence and detection rate of these tumors. NENs can be classified into well differentiated and poorly differentiated neuroendocrine tumors (NETs) or neuroendocrine carcinomas (NECs). The proliferation rate of NETs can vary from Ki-67 1-55%. In addition, the SSTR expression can vary significantly. Because of this high "heterogeneity", their detection and characterization have become essential to disease management, leading to dual-tracer imaging, most commonly with FDG- and SSTR-targeted PET/CT. Because of the complexity of the disease, the optimal treatment of patients depends on a combination of imaging, serological biomarkers, and clinical information. There remains a significant portion of patients who do not respond as anticipated, and the management of their disease remains challenging with current techniques, necessitating the refinement of our technologies and the development of new ones. In addition to new biological targets, improved peptide vector targeting for the somatostatin receptor needs further development. This review aims to evaluate the existing imaging techniques utilized in the diagnosis, assessment, and treatment of NENs, as well as the emerging radiopharmaceuticals and technologies, which will expand our imaging repertoire as well as our management options.