Abstract
Purpose: Somatostatin receptor imaging with (18)F-AlF-NOTA-octreotide ((18)F-AlF-OC) has shown promising performance in neuroendocrine neoplasms (NENs). In this study, we aim to investigate the diagnostic performance and clinical impact of (18)F-AlF-OC in a large prospective cohort of patients with NEN. Methods: Between January 2023 and November 2023, a total of 219 patients with confirmed or suspected NEN were enrolled prospectively and underwent (18)F-AlF-OC PET/CT at 2 h post-injection. The primary endpoint was the diagnostic performance, including sensitivity, specificity, and accuracy. An additional primary endpoint was the impact of (18)F-AlF-OC on clinical management. The reference standard was based on the results of histopathology or radiological follow-up. Results: 205 patients were included in the final analysis. The patient-level sensitivity, specificity, and accuracy of (18)F-AlF-OC PET/CT compared with contrast-enhanced CT/MRI were 90.5% vs. 81.8%, 93.1% vs. 71.1%, and 91.2% vs. 79.4%, respectively. 26 patients had tiny gastrointestinal NENs (smaller than 1 cm in diameter). The patient-based sensitivity of (18)F-AlF-OC PET/CT and contrast-enhanced CT/MRI were 61.5% (16/26) and 37.5% (9/24), respectively. The smallest diameter of gastrointestinal NEN detected by (18)F-AlF-OC PET/CT was 0.6 cm in the rectum, 0.3 cm in the stomach, and 0.5 cm in the duodenum. (18)F-AlF-OC PET/CT results led to changes in clinical management in 19.5% of patients (40/205), owing mainly to new or unexpected findings compared to contrast-enhanced CT/MRI. Conclusion: (18)F-AlF-OC PET/CT demonstrated great diagnostic performance in patients with NEN, particularly for detecting tiny gastrointestinal NEN. Furthermore, (18)F-AlF-OC PET/CT impacted the therapeutic management in 19.5% of patients. Our results further validate the role of (18)F-AlF-OC as a somatostatin receptor imaging tracer in clinical practice.