Prognostic utility of magnetic resonance imaging in neonatal hypoxic-ischemic encephalopathy: substudy of a randomized trial

Abstract

Objective: To investigate the effects of hypothermia treatment on magnetic resonance imaging (MRI) patterns of brain injury in newborns with hypoxic-ischemic encephalopathy compared with normothermia, including the prognostic utility of MRI for death and/or disability at a postnatal age of 2 years.

Design: Substudy of a randomized controlled trial.

Setting: Participating centers in the Infant Cooling Evaluation trial.

Participants: Trial participants (gestational age ≥35 weeks with moderate to severe hypoxic-ischemic encephalopathy, randomized to whole-body hypothermia or normothermia) with available MRIs.

Main exposure: We performed qualitative evaluation of T1- and T2-weighted and diffusion MRIs. The posterior limb of the internal capsule was classified as normal or abnormal, whereas the basal ganglia and thalami, white matter, and cortical gray matter were classified as normal or mildly abnormal or moderately/severely abnormal.

Main outcome measures: Death or major disability at 2 years.

Results: We evaluated 127 MRIs (66 patients treated with hypothermia and 61 with normothermia; mean age at scan, 6 postnatal days). The odds of having moderate/severe white matter or cortical gray matter abnormalities on T1- and T2-weighted MRI were reduced by hypothermia (white matter odds ratio, 0.28 [95% CI, 0.09-0.82]; gray matter odds ratio, 0.41 [0.17-1.00]). Abnormal MRI findings predicted adverse outcomes, with T1- and T2-weighted and diffusion MRI abnormalities in the posterior limb of the internal capsule and basal ganglia and thalami demonstrating the greatest predictive value. There was little evidence that prognostic value of the MRI was modified by therapeutic hypothermia (all interactions, P > .05).

Conclusions: Brain injury on T1- and T2-weighted MRI is reduced in hypothermia-treated newborns. Abnormal MRI findings are prognostic of long-term outcome in moderate to severe hypoxic-ischemic encephalopathy regardless of treatment with hypothermia.