Matched-Pair Comparison of [68Ga]-DOTA-Toc PET/CT and [18F]-SiTATE PET/CT: Frequency of Pitfalls in patients with neuroendocrine tumors (G1-G2)

Ziel/Aim: Recently [18F]SiTATE has emerged as a promising SSTR-PET tracer option for imaging neuroendocrine tumors (NET). We retrospectively evaluated the frequency and characteristics of non-tumor-related uptake in comparison to [68Ga]-DOTA-Toc.

Methodik/Methods: 20 NET patients (G1-G2) were included as matched pairs, who underwent [68Ga] PET/CT and, as a follow-up 13.3±6.5 months later, the novel [18F]SiTATE PET/CT. All PET/CT scans (n=40) were reviewed by 2 nuclear medicine physicians. PET positive findings attributed to a benign origin based on known pitfalls and information from CT were included. The uptake intensity (SUV) of these benign findings was measured using a 50% isocontour volume of interest and compared between tracers.

Ergebnisse/Results: Overall, a total of 166 benign findings were identified, with 75 detected using [68Ga] and 91 with [18F]SiTATE. These findings were 51% physiological, 23% osteoblastic, 26% inflammation. With [68Ga] SUVmean being 8.28±4.4, 1.63±0.48, 3.98±2.04, respectively and 8.38±4.5, 2.38±0.59, 3.57±1.40, respectively for [18F]. Regionally, SUVmean and SUVmax values across specific anatomical sites—including the processus uncinatus, and cervical and presacral ganglia—were largely similar between [18F]SiTATE and [68Ga], with minimal variation. However, [18F]SiTATE demonstrated notable uptake in the gallbladder in 12 out of 20 patients (SUV 9.56±3.15), whereas no prominent gallbladder uptake was observed with [68Ga]. Additionally, [18F]SiTATE showed significant higher accumulation in osteoblastic findings compared to [68Ga](paired t-test p=0.04).

Schlussfolgerungen/Conclusions: In this preliminary analysis physiological findings were largely similar between [18F]SiTATE and [68Ga]. Yet [18F]SiTATE showed significant more uptake in the gallbladder and osteoblastic findings compared to [68Ga]. Further research is required to fully understand these uptake patterns and their implications for clinical interpretation.

Publication History

Article published online:
12 March 2025