18F-FDG PET/CT and 123I-Metaiodobenzylguanidine Imaging in High-Risk Neuroblastoma: Diagnostic Comparison and Survival Analysis

The aim of our study was to evaluate prospectively the diagnostic performance and prognostic significance of F-18-FDG PET/CT in comparison with I-123-metaiodobenzylguanidine (I-123-MIBG) imaging in patients with high-risk neuroblastoma. Methods: Twenty-eight patients with refractory or relapsed high-risk neuroblastoma (16 male and 12 female patients; age range, 2-45 y; median age, 7.5 y) were simultaneously evaluated with F-18-FDG PET/CT and I-123-MIBG imaging before treatment with high-dose I-131-MIBG. We compared the 2 methods in mapping tumor load, according to the extent of disease and intensity of positive lesions identified in each patient. Separate comparisons were performed for the soft-tissue and bone-bone marrow components of tumor burden. Survival analysis was performed to assess the prognostic significance of F-18-FDG and I-123-MIBG imaging parameters. Results: F-18-FDG PET/CT results were positive in 24 of 28 (86%) patients, whereas I-123-MIBG imaging results were positive in all patients. F-18-FDG was superior in mapping tumor load in 4 of 28 (14%) patients, whereas I-123-MIBG was better in 12 of 28 (43%) patients. In the remaining 12 (43%) patients, no major differences were noted between the 2 modalities. F-18-FDG PET/CT missed 5 cases of bone-bone marrow disease, 4 cases of soft-tissue disease, and 6 cases of skull involvement that were positive on I-123-MIBG scans. Cox regression and Kaplan-Meier survival curves showed that the group of patients (4/28) in whom F-18-FDG was superior to I-123-MIBG had a significantly lower survival rate than the others. Tumoral avidity for F-18-FDG (maximum standardized uptake value) and extent of F-18-FDG-avid bone-bone marrow disease were identified as adverse prognostic factors. Conclusion: I-123-MIBG imaging is superior to F-18-FDG PET/CT in the assessment of disease extent in high-risk neuroblastoma. However, F-18-FDG PET/CT has significant prognostic implications in these patients.