Maayke Hunfeld

149 MRI and prognosis MR images were acquired on a 1.5 Tesla scanner (General Electric Healthcare, Milwaukee, MI, USA) using an 8-channel head coil. The scan protocol included an axial T1-weighted sequence, axial T2-weighted sequence, and axial DWI sequence with calculated apparent diffusion coefficient (ADC) map. The degree of hypoxic ischemic injury on neuroimaging was independently assessed by 2 experienced neuroradiologists (MD, AE) on all brain MRI studies. In case of different opinions discussions were started until consensus was reached. A specific neuroimaging scoring systemwas designed for this particular study population based on relevant items of previously published scores and patterns of brain injury (11, 12, 16- 19). The score included assessment of brain injury in different brain areas. Items were scored for presence of injury, degree of injury and location and sidedness of injury, The degree of injury was scored as follows: 1.) No injury. 2.) Focal cortex/white matter injury (<50%) with or without involvement of deep grey matter. 3.) Extensive cortex/ white injury ( ≥ 50% of the cortex/white matter or in 4 or more of the defined brain regions) with or without involvement of deep grey matter. 4.) Involvement of the deep grey matter was divided into basal ganglia and thalami and classified as focal (<50%) or extensive ( ≥ 50%). Injury assessment was based on abnormal signal intensity on T1 and T2-weighted sequences or presence of diffusion restriction (cytotoxic edema) on DWI/ADC. See Supplemental Table 1 for a detailed description. Clinical outcomes Clinical outcome data were collected from patient records and during on-site visits at the follow-up outpatient clinic 2 years post-OHCA (MH, CB). When no follow-up visit took place, these outcomes, if available, were collected from patient records (records of hospital visits in Erasmus MC with other specialists). Neurological outcome was based on PCPC score, a 6-point scale of global neurological function (1 normal; 2 mild disability; 3 moderate disability; 4 severe disability; 5 coma and vegetative state; 6 death), Supplemental Table 2. All PCPC scores were determined by a pediatric neurologist (MH). PCPC scores of 1-2, or no difference between pre- and post-arrest were grouped as good neurological outcome, whereas 3-5 as poor neurological outcome and 6 as death. Children who died were further sub-classified as 1. brain death (BD); 2. death from WLST due to poor neurological prognosis (WLST-neuro); 3 death from WLST due to re-arrest of refractory circulatory or respiratory failure (WLST-cardio-pulmo). 5