Novel ⁶⁸Ga-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 ¹⁸F-FDG PET/CT. ⁶⁸Ga-fibroblast-activation protein inhibitor (FAPI) PET/CT is a new oncologic imaging tool that may overcome this limitation. Methods: We assessed postvaccine head-to-head and same-day ¹⁸F-FDG and ⁶⁸Ga-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. Result: Significant visual lymph node uptake adjacent to the injection site was noted in 11 of 11 (100%) patients with ¹⁸F-FDG PET/CT, versus 0 of 11 (0%) with ⁶⁸Ga-FAPI PET/CT. ¹⁸F-FDG detected 73% and ⁶⁸Ga-FAPI PET/CT 94% of all tumor lesions. Conclusion: In this case-series study, ⁶⁸Ga-FAPI showed its potential to avoid ¹⁸F-FDG PET/CT postvaccination pitfalls and presented superior tumor localization.