Authors: Yuhao Huang; Timothy Singer; Michael Iv; Bryan Lanzman; James Stadler III; Jia Wang; Gerald Grant; Samuel Cheshier; Kristen Yeom (Stanford, CA)

Introduction: Pediatric patients with intracranial arteriovenous malformations (AVMs) undergo digital subtraction angiography (DSA) for surveillance following surgical intervention. However, DSA carries substantial radiation risk, particularly for the pediatric population. We evaluated whether magnetic resonance (MR) with ferumoxytol contrast can be used to surveil residual AVM. Methods: A retrospective cohort was assembled for children treated with AVM from 2014 to 2016 who underwent surveillance by DSA and ferumoxytol-based MR imaging. Arterial spin labeling (ASL) and spoiled gradient recalled acquisition (SPGR) were the MR series used. Two radiologists blinded to DSA results independently assessed MR scans for residual AVM and lesion evolution. Diagnostic confidence was examined using a Likert scale. Sensitivity, specificity, and inter-modality reliability were determined with DSA as the gold standard. Radiation exposure was calculated as total dose area product (TDAP), total air kerma (TAK) and peak air kerma (PAK). Results: Fifteen patients were included in this study (mean: 11 years, range: 3-17). The average time between the first surveillance DSA and subsequent MR was 17 days (SD: 98). Inter-modality agreement was excellent between SPGR and DSA (k = 0.848, p < 0.001), but poor between ASL and DSA (k = 0.393, p = 0.014). Sensitivity and specificity of SPGR and ASL in diagnosing AVM were 92% and 100%, 72% and 100%, respectively. Radiologists reported greater diagnostic confidence with ferumoxytol-based MR versus standard MR. On average, patients received two DSA studies during surveillance. Per DSA, radiation for TDAP, TAK and PAK was 58,632 mGy.cm 2 (95% CI: 38,570 - 78,693), 562 mGy (95% CI: 378 - 747), and 310 mGy (95% CI: 209 - 411), respectively. Two surveillance DSA studies constitute 56% of the 2Gy safety threshold (95% CI: 38-75%). Conclusion: Ferumoxytol-based MR performed similarly to DSA for AVM surveillance in the pediatric population and can be considered an equal alternative.