RT Journal Article SR Electronic T1 SUV Analysis for the Nepenthe Trial: An Evaluation of 123I-mIBG Semi-Quantitative Analysis as a Predictor of Biopsy Yield and Genetic Biomarkers in Relapsed Neuroblastoma JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 119 OP 119 VO 61 IS supplement 1 A1 Alai, Emma A1 Samoyedny, Andrew A1 Mccord, Sandy A1 Srinivasan, Abhay A1 Cahill, Anne Marie A1 States, Lisa YR 2020 UL http://jnm.snmjournals.org/content/61/supplement_1/119.abstract AB 119Introduction: Neuroblastoma (NBL) is the most common extracranial solid tumor in children and accounts for nearly 15% of pediatric cancer fatalities. Nepenthe is a clinical trial for high risk NBL patients who are unresponsive to standard treatment. The trial matches genomic aberrations in NBL cells to targeted inhibitor therapy. 123I-methyliodobenzylguanidine (mIBG) has high sensitivity for NBL and can be used to identify a biopsy site. Purpose: The purpose of this study is to assess the utility of using a quantitative 123I-mIBG SPECT/CT standardized uptake value (SUV) to determine an SUV ratio cutoff value above which a successful biopsy with actionable genetic data can be predicted. Methods: This study includes 14 patients with refractory NBL who underwent 123I-mIBG SPECT/CT scans from 2/2018 to 6/2019 within a month of biopsy. Data was obtained via review of patient medical and pathology records (EPIC EMR) as well as Foundation Medicine Next Generation Sequencing (NGS) genetic reports from Nepenthe records. 123I-mIBG scans with SPECT/CT were performed on Siemens Symbia Intevo scanners. All biospies were performed by interventional radiology. The reports were used to identify the biopsy site to be measured. The lesion morphology was recorded as soft tissue or marrow infiltration confirmed on MRI. Using the Siemens syngovia processing package, standardized uptake values (SUV) were measured using a region of interest (ROI) drawn on the lesion (SUVmax) and background ROIs drawn on the right lobe of the liver and the psoas muscle (SUVmean). Results: In this research, max lesion to mean psoas SUV ratio was used due to lower variability within and between participants than max lesion to mean liver SUV ratio (SD = 0.23 vs SD = 0.99). Psoas to liver SUV ratios can be interchanged as the ratios are highly correlated (R = 0.91, p<0.01). There is a correlation between increasing ratio of lesion SUVmax to psoas SUVmean and increasing tumor cell percentage (%) within the specimen (R2=0.355, p=0.0246). A higher tumor cell % was found to correlate with actionable genetic findings (Pearson’s R = 0.602, p<0.05). This data shows that an SUV ratio of at least 5.0 increases the chance of having a biopsy with a successful high tumor cell %. Conclusions: 1. Quantitation of 123I-mIBG uptake can predict biopsy yield for increased chance of successful NGS testing in order to personalize treatment for children with relapsed or refractory NBL. 2. Background activity using psoas 123I-mIBG SUVmean is a reliable alternative to liver 123I-mIBG SUVmean. 3. An SUV ratio minimum would help clinicians determine the best site for biopsy. If a lesion does not reach the 123I-mIBG SUV minimum for biopsy, a PET scan may be a useful alternative in localizing biopsy sites and predicting biopsy yield.