Objective Brain proton (¹H) magnetic resonance spectroscopy (MRS) lactate/N-acetylaspartate (Lac/NAA) peak area ratio is used for prognostication in neonatal encephalopathy (NE). At 3 Tesla in NE babies, the objectives were to assess: (1) sensitivity and specificity of basal ganglia and thalamus (BGT) ¹H MRS Lac/NAA for the prediction of Bayley III outcomes at 2 years using optimised metabolite fitting (Tarquin) with threonine and total NAA; (2) prediction of motor outcome with diffusion-weighted MRI; (3) BGT Lac/NAA correlation with the National Institute of Child Health and Human Development (NICHD) MRI score.

Subjects and methods 55 (16 inborn, 39 outborn) infants at 39w+5 d (35w+5d–42w+0d) with NE admitted between February 2012 and August 2014 to University College London Hospitals for therapeutic hypothermia underwent MRI and ¹H MRS at 3T on day 2–14 (median day 5). MRIs were scored. Bayley III was assessed at 24 (22–26) months.

Results 16 babies died (1 inborn, 15 outborn); 20, 19 and 21 babies had poor motor, cognitive and language outcomes. Using a threshold of 0.39, sensitivity and specificity of BGT Lac/NAA for 2-year motor outcome was 100% and 97%, cognition 90% and 97% and language 81% and 97%, respectively. Sensitivity and specificity for motor outcome of mean diffusivity (threshold 0.001 mm²/s) up to day 9 was 72% and 100% and fractional anisotropy (threshold 0.198) was 39% and 94%, respectively. Lac/NAA correlated with BGT injury on NICHD scores (2A, 2B, 3).

Conclusion BGT Lac/NAA on ¹H MRS at 3T within 14 days accurately predicts 2-year motor, cognitive and language outcome and may be a marker directing decisions for therapies after cooling.