Maayke Hunfeld

147 MRI and prognosis Introduction In The United States, each year approximately 6000-8000 children experience an out-of-hospital cardiac arrest (OHCA) (1-4). The mortality is high, after achieving return of circulation (ROC) only 38% survives to hospital discharge (5). The causes of death after ROC before hospital discharge are diverse. In a retrospective cohort in our hospital, a tertiary pediatric center, the majority of children (67%) died due to withdrawal of life sustaining therapy (WLST), based on poor neurological prognosis (6). Contributing factors that led to this decision were mainly findings on neurological exam, but also results of ancillary tests such as electroencephalography (EEG) and neuroimaging were included in the decision. Predicting long-term outcome in children after cardiac arrest (CA), especially when they remain comatose the first days after ROC, is challenging (7). The precise role of neuromonitoring methods (neurological exam, electrophysiology, cerebral biomarkers and brain imaging) is still unclear because no single test is 100% accurate yet (8, 9). Brain MRI is a sensitive tool to identify brain injury after hypoxia-ischemia. Specifically, diffusion-weighted imaging (DWI) can reliably detect acute and early subacute findings of ischemia (10). However, the evidence of MRI brain abnormalities in children post-CA related to long-term outcome, is weak: over the past 20 years, only a limited number of studies with small sample sizes investigated the association between MRI findings and outcome (11-13). All studies included heterogenic groups of both in-hospital cardiac arrest (IHCA) and OHCA patients. Outcome was mainly short-term and the timing of brain MRI differed in these cohorts (ranging from 1 up to 14 days post-CA). Recently, Kirschen et al. showed that children (n=77, inclusion period 2005-2013) after OHCA with unfavorable outcomes at hospital discharge showed more extensive lesions on DWI and T2/fluid attenuated inversion recovery (FLAIR) MRI sequences, performed within 14 days post-arrest, compared to children with favorable outcomes (14). Studies on long-term outcome are lacking. The purpose of our study was to examine whether early brain MRI including DWI predicts neurological outcome at hospital discharge and 2 years post-OHCA in the individual pediatric patient. We hypothesized that a normal brain MRI is predictive for a good outcome. 5