Evaluation of [¹⁸F]alf-Nota-octreotide PET/CT in Routine Clinical Use: a Retrospective Analysis in 288 Neuroendocrine Tumor Patients

Fluorine-18-labeled somatostatin receptor (SSTR) tracers are increasingly adopted as an alternative to generator-produced gallium-68 compounds for imaging neuroendocrine neoplasms (NENs). While [¹⁸F]AlF-NOTA-octreotide ([¹⁸F]AlF-OC) has shown comparable or even superior diagnostic performance in controlled clinical studies, real-world evidence remains limited, particularly for underrepresented NEN subtypes. This study evaluates the clinical implementation, biodistribution, and uptake characteristics of [¹⁸F]AlF-OC PET/CT in routine practice across the full NEN spectrum. In this retrospective single-center analysis, all patients referred for SSTR PET/CT between March 2023 and January 2024 were included. Relevant clinical and demographic data, along with procedural details, were collected. Lesions were segmented semi-automatically using MIM version 7.3.4 and quantitatively assessed. Uptake patterns were analyzed according to tumor grade, primary tumor origin, organ site and clinical indication. A total of 322 scans were performed in 288 patients (median age 64 years). The cohort included 93 Grade 1 (G1), 84 G2, 17 G3 NETs and 3 neuroendocrine carcinomas of gastroenteropancreatic (GEP) or unknown origin, alongside 15 phaeochromocytoma/paraganglioma (PPGL) cases and 40 lung NETs. In total, 4,677 lesions were evaluated. Mean injected activity was 208.5 ± 73.6 MBq with an average uptake time of 121 ± 14 min. G3 NETs demonstrated sufficient uptake (mean SUVmax 19.0), comparable to low-grade NETs. Uptake varied by primary origin, with the highest mean SUVmax values observed in gastric (53.3), sigmoidal (22.0), rectal (20.5), small intestinal (19.1) and pancreatic NETs (17.1). Lung NETs (17.0) also have comparable uptake. Strong tracer avidity was observed in lesions within the liver (19.8) and bone (12.1). Physiological distribution was consistent with known SSTR-expressing tissues. This large real-world series confirms that [¹⁸F]AlF-OC PET/CT is a robust and broadly applicable SSTR imaging modality across diverse NEN subtypes, including tumor groups traditionally underrepresented in prospective trials of SSTR tracers. The tracer demonstrates reliable uptake across grades and organ sites, supporting its routine clinical use as a practical, high-throughput alternative to ⁶⁸Ga-labeled SSAs.