Imaging for PRRT Selection and Response Assessment in Neuroendocrine Neoplasms: Is SSTR Pet/Ct Sufficient?

Peptide receptor radionuclide therapy (PRRT) has emerged as an established treatment option for selected patients with advanced somatostatin receptor (SSTR) – positive neuroendocrine neoplasms, particularly well – differentiated gastroenteropancreatic neuroendocrine tumors (GEP – NETs). In this setting, imaging is central not only to treatment selection, but also to biological risk stratification and post-treatment response evaluation. This structured narrative review examines the role of SSTR PET/CT, 18F – FDG PET/CT, and conventional cross – sectional imaging in PRRT candidate selection and response assessment. The literature search was performed in PubMed and focused on studies published from 2015 onward, with additional targeted identification of landmark clinical trials, consensus statements, and practice recommendations. Available evidence indicates that baseline SSTR PET/CT is essential for PRRT eligibility assessment, however, receptor positivity alone may be insufficient in biologically heterogeneous disease. In selected patients, particularly those with intermediate- or high-grade tumors, rapid progression, or discordance between clinical behavior and receptor imaging findings, 18F-FDG PET/CT provides complementary information on tumor aggressiveness and lesion-level heterogeneity. After PRRT, response assessment continues to rely predominantly on CT or MRI and RECIST 1.1, although this framework remains suboptimal in indolent, multifocal, bone-predominant, or mixed-response disease. Overall, current evidence supports a multimodal imaging strategy in which SSTR PET/CT remains the central theranostic tool, but is interpreted in conjunction with clinical context, cross-sectional imaging, and selective use of 18F-FDG PET/CT.