Synthesis and PET Imaging of [68Ga]Ga-FAPI-46

The synthesis of [⁶⁸Ga]Ga-FAPI-46 was performed as previously described [15 (link)]. Briefly, we obtained ⁶⁸Ga from our in-house ⁶⁸Ge/⁶⁸Ga generator (iThemba LABS, Somerset West, South Africa). The FAPI peptide was obtained from SOFIE Biosciences, Inc., Culver City, CA, USA. The radiolabeling was conducted in-house and the labelling efficiency exceeded 95%. There was no specific patient preparation applied for the [⁶⁸Ga] Ga-FAPI PET scan. The mean injected activity of [⁶⁸Ga]Ga-FAPI was 5 ± 0.6 mCi/185 ± 22.2 MBq (range: 4.2–6 mCi). After an uptake period of 60 min, we acquired whole-body (vertex to mid-thigh) images. PET imaging was acquired in 3D mode at 3 min per bed position. Ordered subset expectation maximization (OSEM) iterative reconstruction algorithm (four iterations, eight subsets) was performed on the images followed by post-reconstruction filtering. The CT scan was a non-diagnostic scan and was performed in line with recommendations and as per our departmental protocol (previously published [26 (link)]). All patients were imaged on one of two systems, namely the Biograph 40 Truepoint PET/CT scanner (Siemens Medical Solutions, Hoffman Estates, IL, USA) and the Biograph Vision 450 PET/CT scanner (Siemens Medical Solutions, IL, USA).