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Background
Peptide receptor radionuclide therapy (PRRT) is a novel targeted radiopharmaceutical treatment used for neuroendocrine tumors (NETs), primarily those arising from the gastrointestinal tract. Patients receive an IV injection of a peptide-conjugated with a radioisotope for therapy, 177Lutetium (177Lu). The radioligands, octreotide (DOTATOC) or octreotate (DOTATATE), bind to somatostatin receptors on tumor cells, are subsequently internalized and induce cell killing by beta irradiation. Approved by the FDA in 2018, PRRT with 177Lu-DOTATATE is a novel treatment for those with advanced, metastatic NETs that are not suitable for surgery or unresponsive to other treatments. The treatment involves up to four sessions, typically outpatient, spaced about 8 weeks apart, each lasting approximately 6 hours. The unique mechanism of this therapy is to deliver radiation directly to tumor cells, primarily sparing healthy tissues. By slowing or halting tumor progression, providing symptom relief, and improving the quality of life, treatment with minimal to no side effects is a game changer for many patients. Research into PRRT is rapidly growing, with ongoing clinical trials exploring various peptides, isotopes, and combinational therapies to boost efficacy.

Educational Goals / Teaching Points
The purpose of this case-based pictorial exhibit is to enable participants to gain a comprehensive understanding of PRRT as a specialized and targeted treatment for NETs. 1) Identify the clinical and imaging features associated with NETs. 2) Define PRRT and its primary application in treating NETs, particularly those originating from the gastroentero-pancreatic system. 3) Recognize the key properties of radionuclides used in PRRT, such as 177Lu, and the mechanism of how these drugs target tumor cells and induce tumor-killing. 4) Understand the significance of 177Lu-DOTATATE in treating advanced NETs. 5) Understand a typical 177Lu-DOTATATE treatment plan. 6) Identify the side effects of the treatment, their management strategies, recognize essential radiation safety measures, and understand other related procedural topics. 7) Participants will also learn current research pathways, including ongoing clinical trials aimed to enhance efficacy of PRRT through various combinatorial methods.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
We present a case-based multimodality pictorial review with 68Gallium-DOTATATE PET-CT, CT, ultrasound, and MRI to highlighting the key concepts in diagnosis and management of NETs. We will also talk about the implementation of a radioligand treatment program based on our own home institutional experience.

Conclusion
PRRT is a novel targeted treatment of NETs; leveraging the cutting-edge combination of radiopharmaceutical and molecular imaging techniques to target and treat metastatic tumors. PRRT offers many patients with advanced and metastatic NETs an effective, and well-tolerated treatment option.