Semi-quantitative MIBG scores in relapsed/refractory neuroblastoma: Prognostic insights from post-131I-MIBG treatment scans and impact of SPECT-CT imaging.

Objectives: Neuroblastoma often demonstrates high uptake of MIBG, which is used for imaging and therapy. This retrospective observational study aimed to assess the prognostic significance of modified Curie scores (mCS) and SIOPEN scores (SS) derived from post-treatment ¹³¹I-MIBG scans in relapsed/refractory neuroblastoma. Additionally, the impact of SPECT-CT imaging on these scores was investigated as a secondary goal.

Material and methods: Pediatric patients with relapsed/refractory neuroblastoma, who underwent ¹³¹I-MIBG treatment, were included (n=35). mCS and SS were calculated from planar images of post-treatment ¹³¹I-MIBG scans. Patients were then categorized based on the cut-off values obtained from these scans, and survival analysis was conducted. To investigate the impact of SPECT-CT imaging on scores, mCS and SS were also calculated from both planar and SPECT-CT images of diagnostic ¹²³I-MIBG scans separately.

Results: Patients with mCS>12 or SS>23 on post-treatment ¹³¹I-MIBG scans had significantly worse overall survival. mCS and SS from SPECT-CT were significantly higher than planar images in pre- and post-treatment diagnostic ¹²³I-MIBG scans. SPECT-CT caused changes in mCS for 61% and SS for 55% of patients, predominantly in axial and appendicular skeleton regions.

Conclusions: Both mCS and SS from post-treatment ¹³¹I-MIBG planar scans correlated significantly with overall survival in relapsed/refractory neuroblastoma. Patients with mCS>12 or SS>23 had poorer survival. SPECT-CT imaging influenced scores for a substantial portion of patients, emphasizing its value alongside planar imaging. Larger, comprehensive studies are warranted to validate these findings and refine prognostic cut-offs. Incorporating SPECT-CT in relevant body regions is recommended for improved disease assessment.