Detecting Isolated Multifocal Leptomeningeal Metastases With 18F-MFBG PET/CT in a Pediatric Patient With High-risk Neuroblastoma.

A 2-year-old girl was diagnosed with high-risk neuroblastoma. Baseline 18F-MFBG PET/CT demonstrated primary abdominal disease with concurrent multiple metastases. Following induction therapy, restaging 18F-MFBG PET/CT did not show any abnormal 18F-MFBG uptake. However, at six-month follow-up, repeat 18F-MFBG PET/CT revealed multifocal 18F-MFBG-avid lesions confined exclusively to the cranial compartment, with no evidence of extracranial disease recurrence. Subsequent contrast-enhanced brain MRI confirmed the presence of leptomeningeal metastases. This case illustrates that isolated multifocal leptomeningeal metastases may be reliably detected on 18F-MFBG PET/CT, underscoring the utility of this modality in the surveillance of central nervous system involvement in pediatric patients with neuroblastoma.