Intense Focal Renal 18F-MFBG Uptake Attributable to Radiation in a Pediatric Patient With Neuroblastoma

A 9-year-old boy with neuroblastoma was enrolled in a clinical trial. After radiotherapy to the primary tumor site, 18 F-MFBG PET/CT was performed 2 months later. No abnormal radiotracer accumulation suggestive of metastatic disease was identified. However, focal intense 18 F-MFBG uptake was observed in the upper pole of the left kidney, within the previously irradiated field. No structural renal lesion was identified on cross-sectional imaging, and no evidence of renal tumor was found during 12 months of clinical and imaging follow-up. This case illustrates that intense localized renal 18 F-MFBG uptake may result from radiation and should be recognized as a potential pitfall in post-radiotherapy 18 F-MFBG PET/CT interpretation.