Whole-Body MRI and Whole Body [123I]-I-mIBG Scintigraphy: a Comparison in Intermediate and High Risk Neuroblastoma and validation of SIOPEN Scoring System in WB-MRI

Purpose: To assess the agreement between 123I-metaiodobenzylguanidine or [123I]-I-mIBG and Whole Body Magnetic Resonance Imaging with diffusion-weighted whole-body imaging with background body signal suppression (WB MRI-DWIBS) in High and Intermediate risk Neuroblastoma, a retrospective review was performed on [123I]-I-mIBG and DWIBS paired scans acquired at diagnosis, response-to-therapy, after-surgery, off therapy and after relapse with systemic involvement, and osteo-bone marrow metastatic load was evaluated for each of them. Methods: 80 paired [123I]-I-mIBG and DWIBS scans were acquired for 31 patients between June 2009 and June 2019 within 30 days and without intercurrent therapy. SIOPEN Semi-quantitative Scoring Systems for NB with 12 body sections was applied at whole body MIBG and WB MRI-DWIBS acquired to evaluate the skeletal disease extent. In each case thoracic-abdominal SPECT was used to confirm or exclude doubtful scintigraphic alterations. We evaluated specificity, sensitivity, overall accuracy, positive predictive value (PPV) and negative predictive value (NPV) of WB MRI-DWIBS respect [123I]-I-mIBG scintigraphy considered as gold standard. The inverse theoretical statistic exercise was performed for [123I]-I-mIBG respect DWIBS results. Results: DWIBS and [123I]-I-mIBG images were concordant in 890 out of the 960 analyzed segments, with high agreement between the two techniques (Kendal=0.85 P < 0.0001 and Chi 536.5975 P < 0.0001). Considering [123I]-I-mIBG as gold standard, WB MRI-DWIBS overall accuracy was 93%, sensitivity 78%, specificity 95%, PPV 77% and NPV 96%. Otherwise, on the theoretical statistic exercise, [123I]-I-mIBG overall accuracy was 93%; sensitivity 77%; specificity 97%; VPP 78%; VPN 95%, respect DWIBS. [123I]-I-mIBG and WB MRI-DWIBS SIOPEN scoring resulted superimposable (Rho Spearman=0.88, P < 0.0001). Conclusion: DWIBS and [123I]-I-mIBG images showed a very high concordance: a first validation of SIOPEN Scoring System seems possible on the basis of these data. WB MRI may represent an alternative in weak-avid MIBG tumors and for follow up assessment. A multimodal imaging protocol is proposed for High and Intermediate Risk protocols.