Abstract
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Objectives: Neuroblastoma is most common extracranial solid malignancy of childhood. Metastatic disease is seen in more than half of neuroblastoma patients at the time of diagnosis. 131I-MIBG scintigraphy & 18F-DOPA PET/CT are established imaging modalities in evaluation of neuroblastoma. As of now none of the studies has described disease extent in the patients of neuroblastoma using standardised scoring methods. We aim to compare 131I-MIBG and 18F-DOPA PET/CT in picking up the lesions and to evaluate extent of the disease using standardised scoring methods i.e SIOPEN and Curie Scoring systems.
Methods: Biopsy proven consecutive neuroblastoma patients underwent 131I-MIBG (planar & SPECT/CT) scan and 18F-DOPA PET/CT scan within 1 month of each scan at random. 131I-MIBG scan was done following 37±12 MBq intravenous administration of 131I-MIBG and imaging was acquired after 48-72 hours. Planar images were obtained and single photon emission computed tomography/Computed tomography (SPECT/CT) of the region of interest were performed. 18F-DOPA PET/CT was done following 5 MBq/kg intravenous administration of 18F-DOPA and imaging was acquired after 45-60 min. Curie and SIOPEN system scoring of both the modalities were compared and correlation between the same were assessed. Number of lesions detected in planar 131I-MIBG vs MIP image of 18F-DOPA and SPECT/CT vs fused PET/CT images were correlated.
Results: In total 35 patients were included, 23 were males and 12 females. Patients age ranged from 3 months to 84 months (Mean age was 33 ± 22 months). Out of 35 patients, 24 patients were indicated for initial staging and 11 patients for restaging. They were staged according to INRGSS staging (L=7, L2=9, M=13, MS=6). MYCN gene evaluation was done in 5 patients (1=positive, 4=negative). In 13 patients urinary catecholamines were elevated. Bone marrow biopsy was performed in 23 patients, out of which 12 were positive & 11 were negative. Both 131I-MIBG & 18F-DOPA PET/CT scan was positive in 31 patients & negative in 4 patients. Curie score in 131I-MIBG scan ranged from 0-28 (Mean - 6.51) and in 18F-DOPA PET/CT ranged from 0-30 (Mean - 7.94). SIOPEN score in 131I-MIBG ranged from 0-44 (Mean - 8.14) and in 18F-DOPA PET/CT ranged from 0-51 (Mean - 9.94). Strong correlation in describing the disease extent was noted between 131I-MIBG and 18F-DOPA in both Curie (Spearman correlation, ρ = 0.79) and SIOPEN scoring (ρ = 0.85). Total no. of lesions detected in planar 131I-MIBG v/s MIP 18F-DOPA were 192 v/s 273 (ρ = 0.86). Total no. of lesions SPECT/CT 131I-MIBG v/s fused PET/CT 18F-DOPA were 173 v/s 297 (ρ = 0.76). Higher number of bone/bone marrow lesions were picked up on 18F-DOPA PET/CT.
Conclusions: Total number of lesions picked up were more in 18F-DOPA MIP and corresponding PET/CT images in comparison to 131I-MIBG planar and SPECT/CT images, respectively.