Abstract
Fluorine-18-labeled somatostatin analogs (SSAs) could represent a valid alternative to the current gold standard gallium-68-labeled SSAs for somatostatin receptor (SSTR) imaging in patients with neuroendocrine tumors (NETs), given their logistical advantages. Recently, 18F-AlF-NOTA-octreotide (18F-AlF-OC) has emerged as a promising candidate, but a thorough comparison with 68Ga-DOTA-SSA in large patient groups is needed. This prospective, multicenter trial aims to demonstrate non-inferiority of 18F-AlF-OC compared with 68Ga-DOTA-SSA PET in NET patients (ClinicalTrials.gov: NCT04552847). Methods: Seventy-five patients with histologically confirmed NET and a routine clinical 68Ga-DOTATATE (n = 56) or 68Ga-DOTANOC (n = 19) PET, performed within a 3-month interval of the study scan (median: 7 days; range: -30 to +32 days), were included. Patients underwent a whole-body PET, two hours after IV injection of 4 MBq/kg 18F-AlF-OC. A randomized, blinded consensus read was performed by two experienced readers to count tumor lesions. Following unblinding, the detection ratio (DR) was determined for each scan, i.e. the fraction of lesions detected on a scan compared to the union of lesions of both scans. The differential detection ratio (DDR; difference in DR between 18F-AlF-OC and 68Ga-DOTATATE/NOC) per patient was calculated. Tracer uptake was evaluated by comparing SUVmax and tumor-to-background ratios (TBRs) in concordant lesions. Results: In total, 4709 different tumor lesions were detected, 3454 with 68Ga-DOTATATE/NOC and 4278 with 18F-AlF-OC. The mean DR with 18F-AlF-OC was significantly higher than with 68Ga-DOTATATE/NOC (91.1% vs. 75.3%; P<10-5). The resulting mean DDR was 15.8% with a lower margin of the 95% confidence interval (95% CI: 9.6%–22.0%) higher than -15%, the pre-specified boundary for non-inferiority. The mean DDR for the 68Ga-DOTATATE and 68Ga-DOTANOC subgroups were 11.8% (95% CI: 4.3–19.3) and 27.5% (95% CI: 17.8–37.1), respectively. The mean DDR for most organs was higher than zero, except for bone lesions (mean DDR -2.8% (95% CI: -17.8–12.2)). No significant differences in mean SUVmax were observed (P = 0.067), but mean TBR was significantly higher with 18F-AlF-OC than with 68Ga-DOTATATE/NOC (31.7±36.5 vs. 25.1±32.7; P = 0.001). Conclusion: 18F-AlF-OC is non-inferior and even superior compared with 68Ga-DOTATATE/NOC PET in NET patients. This validates 18F-AlF-OC as an option for clinical practice SSTR PET.
- Neuroendocrine
- Oncology: Endocrine
- PET
- PET/CT
- Radiopharmaceuticals
- 18F-AlF-NOTA-octreotide
- 68Ga-DOTANOC
- 68Ga-DOTATATE
- neuroendocrine tumor
- somatostatin receptor
- Copyright © 2022 by the Society of Nuclear Medicine and Molecular Imaging, Inc.