Proceedings of the 13th International Newborn Brain Conference: Neuro-imaging studies.

BACKGROUND/PURPOSE: Therapeutic hypothermia (TH) initiated within the fi rst 6 hours after birth, is proven to decrease brain tissue injury in moderate to severe neonatal encephalopathy (NE) and improve 18-24 month neurological outcomes.Recently, a correlation between the resistive index (RI) of the anterior cerebral artery on head ultrasound (HUS) performed after rewarming and severity of injury on MRI was reported.It remains unknown whether early RI anomalies (before rewarming) may be associated with severity of injury on MRI and as such, might have prognostic value for infants too unstable to undergo an MRI within the optimal time window.The aim of this study was to evaluate: (i) the association between a low anterior cerebral artery RI on HUS obtained during active TH and the severity of brain injury on MRI, and to examine the association between the RI value and outcomes at 48 months of age. METHODOLOGY:A retrospective study was performed.Electronic patient data records and patient charts were reviewed to identify infants born ≥35 weeks of gestation between October 2009 and December 2016, who received TH, at the Children's Hospital of Eastern Ontario.RI on HUS in the fi rst three days of life were compared to brain MRI fi ndings based on the scoring system by Weeke et al.Outcomes at 48 months of life were based on the Ages and Stages questionnaire administered during a clinic visit.RESULTS: Of the 101 newborns (median 39 weeks (IQR 38, 40); median birth weight 3.4 kg (IQR 3.0-3.8))who underwent TH, 74 had doppler ultrasound of the anterior cerebral artery.The median age at which TH was achieved was 5.8 hours of life (IQR = 4.0 -8.1).The median (IQR) for time to fi rst ultrasound was 16.5 (10.7-24.3)hours.The mean RI in the initial ultrasound was 0.65 (IQR 0.59 -0.73).62 newborns had brain MRI, with a median of the total Weeke score of 2.5 (IQR = 0 -11); the median grey matter score was 0 (IQR 0.0 -4.0).Overall, there is little to no correlation between the mean RI and total Weeke score.There is a weak negative correlation between the mean RI and the Weeke grey matter score (Pearson(95% CI): -0.37 (-0.57-0.13;p-value=0.05).The logistic regression model, did not show any signifi cant association between mean RI and neurologic outcome at 48 months (p=0.39).CONCLUSION: Despite the small sample size of the study cohort, the mean RI of the anterior cerebral artery shows some degree of correlation with the Weeke grey matter score on MRI.This suggests it may be helpful as a