In the setting of ongoing COVID-19 vaccination, vaccine-related tracer uptake in locoregional lymph nodes has become a well-known issue in tumor staging by 18 F-FDG PET/CT. 68 Ga-FAPI PET/CT is a new oncologic imaging tool that may overcome this limitation.Methods: We assessed post-vaccine, head-to-head and same-day 18 F-FDG and 68 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, following vaccination within 6 weeks, were eligible for investigation.Result: Significant visual lymph node uptake adjacent to the injection site was noted in 11/11 (100%) patients with 18 F-FDG PET/CT versus 0/11 (0%) with 68 Ga-FAPI PET/CT. 18 F-FDG detected 73% and 68 Ga-FAPI PET/CT 94% of all tumor lesions. Conclusion:In this case-series study, 68 Ga-FAPI showed its potential to avoid 18 F-FDG-PET/CT post-vaccination pitfalls and presented superior tumor localization.Squibb, Celgene, Eisbach Bio, Roche/Genentech; he holds ownership and serves on the Board of Directors of Pharma15, all outside the submitted work.Benedikt M. Schaarschmidt received a research grant from PharmaCept for an undergoing investigator-initiated study not related to this paper.

We aim to evaluate the efficacy and safety of 124 I-metaiodobenzylguanidine (MIBG) dosimetry-guided high-activity 131 I-MIBG therapy of advanced pheochromocytoma or neuroblastoma. Methods: Fourteen patients with advanced pheochromocytoma or neuroblastoma, age 9-69 y, underwent 124 I-MIBG PET scans and whole-body retention measurements to assess the whole-body dose as a surrogate of bone marrow toxicity and tumor (absorbed) dose per unit of administered activity. Dosimetry results together with individual patient characteristics were combined to guide a single therapeutic activity to achieve a high tumor dose without exceeding toxicity threshold. Toxicity was assessed for hematologic, hepatic, and renal function. Response was evaluated by RECIST, International Society of Pediatric Oncology Europe Neuroblastoma-like score, change in PET uptake, and quantitative PET parameters (SUV max , SUV peak , metabolic tumor volume, total lesion glycolysis), as well as visual decrease in number or in visual intensity of lesions on baseline to follow-up 124 I-MIBG PET/CT. Results: The average therapeutic activity was 14 GBq. Eleven of 14 patients (79%) received each more than 10 GBq. One male patient was treated with a single activity of 50 GBq. Three patients were treated with lower activities between 3.5 and 7.0 GBq. Median overall survival was 85 mo (95% CI), and median progression-free survival was 25 mo (95% CI). Four (29%) and 5 (36%) patients demonstrated response (complete response or partial response) by RECIST and functional imaging, respectively. One patient exceeded whole-body dose of 2 Gy and demonstrated grade 3 hematologic toxicity, which resolved spontaneously within 12 mo after the therapy without the need for further treatment. Three patients (21%) demonstrated transient grade 1 renal toxicity. Conclusion: 124 I-MIBG dosimetry-guided high-activity 131 I-MIBG therapy in patients with advanced pheochromocytoma or neuroblastoma resulted in durable responses with a low rate of manageable adverse events. Efficacy of 124 I-MIBG-guided activity escalation should further be assessed in a prospective setting.

This cohort study examines positron emission tomography in renal cell carcinoma and its association with overall survival among adults.