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

Abstract

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