Comparison of Iodine-123 Metaiodobenzylguanidine scintigraphy with SPECT/CT and Fluorine-18-aluminum fluoride-1,4,7-triazacyclononane-1,4,7-triacetic acid-octreotide PET/CT in recurrent High-risk neuroblastoma after complete remission.

Abstract

To evaluate and compare the diagnostic performance of fluorine-18-aluminum fluoride-1,4,7-triazacyclononane-1,4,7-triacetic acid-octreotide (¹⁸F-AlF-NOTATATE) PET/CT and iodine-123 Metaiodobenzylguanidine (¹²³I-MIBG) scintigraphy with SPECT/CT in detecting recurrent high-risk neuroblastoma (HR-NB) after complete response (CR), and to evaluate their impact on clinical decision-making. This retrospective study included 68 HR-NB patients (67 with confirmed recurrences, 1 without recurrence) who underwent ¹⁸F-AlF-NOTATATE PET/CT and ¹²³I-MIBG scintigraphy with SPECT/CT within 7 days. Imaging findings were analyzed for sensitivity, lesion patterns, anatomical locations, spatial distribution, and semiquantitative Curie scores. The impact on clinical management was evaluated by comparing actual versus hypothetical treatment decisions. Recurrence was confirmed using a composite reference standard (histopathology or ≥ 6-month of imaging/clinical follow-up). ¹⁸F-AlF-NOTATATE PET/CT demonstrated numerically higher sensitivity than ¹²³I-MIBG scintigraphy with SPECT/CT (97.0% vs. 88.2%). The combined use of both modalities achieved 100% sensitivity, a statistically significant improvement over either single modality (p < 0.001). Recurrences predominantly exhibited focal/mixed patterns (94.0%) and distant metastases (82.0%; p < 0.001). ¹⁸F-AlF-NOTATATE PET/CT yielded significantly higher Curie scores (p = 0.002). Clinically, ¹⁸F-AlF-NOTATATE PET/CT influenced therapeutic decisions in 37.5% of cases, versus 5% for ¹²³I-MIBG scintigraphy with SPECT/CT alone. Combined imaging affected management in 58.8% of cases (72.5% therapeutic shifts). ¹⁸F-AlF-NOTATATE PET/CT provides critical complementary value to ¹²³I-MIBG scintigraphy with SPECT/CT. It provides a numerical sensitivity benefit, mitigates MIBG non-avidity limitations, and informs clinical decision-making. The combined use of both imaging modalities achieves 100% sensitivity, supporting the integration of this dual-modality approach into HR-NB surveillance protocols.