Clinical experience with ¹⁸F-fluorodeoxyglucose positron emission tomography and ¹²³I-metaiodobenzylguanine scintigraphy in pediatric neuroblastoma: Complementary roles in follow-up of patients

Purpose: To evaluate the potential utility of ¹²³I-metaiodobenzylguanine (¹²³I-MIBG) scintigraphy and 18F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) for the detection of primary and metastatic lesions in pediatric neuroblastoma (NBL) patients, and to determine whether ¹⁸F-FDG PET is as beneficial as 123I-MIBG imaging. Methods: We selected 8 NBL patients with significant residual mass after operation and who had paired ¹²³I-MIBG and ¹⁸F-FDG PET images that were obtained during the follow-up. We retrospectively reviewed the clinical charts and the findings of 45 paired scans. Results: Both scans correlated relatively well with the disease status as determined by standard imaging modalities during follow-up; the overall concordance rates were 32/45 (71.1%) for primary tumor sites and 33/45 (73.3%) for bone-bone marrow (BM) metastatic sites. In detecting primary tumor sites, ¹²³IMIBG might be superior to ¹⁸F-FDG PET. The sensitivity of ¹²³I-MIBG and ¹⁸F-FDG PET were 96.7% and 70.9%, respectively, and their specificity were 85.7% and 92.8%, respectively. ¹⁸F-FDG PET failed to detect 9 true NBL lesions in 45 follow-up scans (false negative rate, 29%) with positive ¹²³I-MIBG. For bone-BM metastatic sites, the sensitivity of ¹²³I-MIBG and F18-FDG PET were 72.7% and 81.8%, respectively, and the specificity were 79.1% and 100%, respectively. ¹²³I-MIBG scans showed higher false positivity (20.8%) than ¹⁸F-FDG PET (0%). Conclusion: ¹²³I-MIBG is superior for delineating primary tumor sites, and ¹⁸F-FDG PET could aid in discriminating inconclusive findings on bony metastatic NBL. Both scans can be complementarily used to clearly determine discrepancies or inconclusive findings on primary or bone-BM metastatic NBL during follow-up.