123 I-mIBG scintigraphy in neuroblastoma: development of a SIOPEN semi-quantitative reporting ,method by an international panel.

Purpose: A robust method is required to standardise objective reporting of diagnostic ¹²³ I-mIBG images in neuroblastoma. Prerequisites for an appropriate system are low inter- and intra-observer error and reproducibility across a broad disease spectrum. We present a new reporting method, developed and tested for SIOPEN by an international expert panel.
Method: Patterns of abnormal skeletal ¹²³ I-mIBG uptake were defined and assigned numerical scores [0-6] based on disease extent within 12 body segments. Uptake intensity was excluded from the analysis. Data sets from 82 patients were scored independently by six experienced specialists as unblinded pairs (pre- and post-induction chemotherapy) and in random order as a blinded study. Response was defined as ≥50 % reduction in post induction score compared with baseline.
Results: In total, 1968 image sets were reviewed individually. Response rates of 88 % and 82 % were recorded for patients with baseline skeletal scores ≤23 and 24-48 respectively, compared with 44 % response in patients with skeletal scores >48 (p = 0.02). Reducing the number of segments or extension scale had a small but statistically negative impact upon the number of responses detected. Intraclass correlation coefficients [ICCs] calculated for the unblinded and blinded study were 0.95 at diagnosis and 0.98 and 0.99 post-induction chemotherapy, respectively.
Conclusions: The SIOPEN mIBG score method is reproducible across the full spectrum of disease in high risk neuroblastoma. Numerical assessment of skeletal disease extent avoids subjective evaluation of uptake intensity. This robust approach provides a reliable means with which to examine the role of 123I mIBG scintigraphy as a prognostic indicator in neuroblastoma.
Competing Interests: Compliance with ethical standards All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. This article does not contain any studies with animals performed by any of the authors. Informed consent Informed consent was obtained from all individual participants or legitimate representatives included in the study. Funding Charity Adam’s Hats supported the pilot study. The trial RDE database was supported by grants provided by Amgen International and Amgen UK. EC grant QLRI-CT-2002-01768 for the SIOPEN-R-NET project supporting national and international data management. Conflict of interest Lewington V declares that she has no conflict of interest. Poetschger U declares that she has no conflict of interest. Lambert B declares that she has no conflict of interest. Bar Sever Z declares that he has no conflict of interest. Castellani MR declares that she has no conflict of interest. Lynch T declares that he has no conflict of interest. Giammarile F declares that he has no conflict of interest. McEwan AJB declares that he has no conflict of interest. Shulkin B declares that he has no conflict of interest. Staudenherz A declares that he has no conflict of interest. Mario Drobics declares that he has no conflict of interest. Ladenstein R declares that she has no conflict of interest.