Novel Ga-FAPI PET/CT Offers Oncologic Staging Without COVID-19 Vaccine-Related Pitfalls.

In the setting of ongoing coronavirus disease 2019 vaccination, vaccine-related tracer uptake in locoregional lymph nodes has become a well-known issue in tumor staging by F-FDG PET/CT. Ga-fibroblast-activation protein inhibitor (FAPI) PET/CT is a new oncologic imaging tool that may overcome this limitation. We assessed postvaccine head-to-head and same-day F-FDG and Ga-FAPI-46 PET/CT findings in a series of 11 patients from a large, prospective imaging registry. All patients with documented tracer uptake in locoregional lymph nodes on PET/CT or PET/MRI, after vaccination within 6 wk, were eligible for investigation. Significant visual lymph node uptake adjacent to the injection site was noted in 11 of 11 (100%) patients with F-FDG PET/CT, versus 0 of 11 (0%) with Ga-FAPI PET/CT. F-FDG detected 73% and Ga-FAPI PET/CT 94% of all tumor lesions. In this case-series study, Ga-FAPI showed its potential to avoid F-FDG PET/CT postvaccination pitfalls and presented superior tumor localization.