Magnetic Resonance Biomarkers in Neonatal Encephalopathy (MARBLE)

N-acetylaspartate (NAA) is a surrogate neuronal marker and its proton magnetic resonance spectroscopy (1H MRS) signal decreases with increasing neuronal mortality associated with cerebral hypoxia-ischaemia. The MRS lactate (Lac)/NAA peak-area ratio increases during and after severe cerebral hypoxia-ischaemia reflecting mitochondrial injury and impaired oxidative phosphorylation.

Aims: (1) To establish normative ranges for thalamic 1H MRS NAA concentration and Lac/NAA in healthy newborn infants (2) To examine the accuracies of thalamic 1H MRS NAA concentration and Lac/NAA for predicting adverse neurodevelopmental outcome in neonatal encephalopathy (NE)

Design: Prospective observational study Methods: Year 1: Following 1H MRS methodology optimisation 40 healthy control infants will be recruited to collect normative data. Year 2 to 3: 115 infants with NE, undergoing therapeutic hypothermia will be recruited. MRS will be performed aged less than 4 days and 7 to 14 days and thalamic NAA levels and Lac/NAA will be quantified; Qualitative interviews to evaluate parental understanding of this biomarker. Year 4, 5: Outcome assessment by BSID III at 18 months.

Outcomes: Mean thalamic NAA levels and Lac/NAA and appropriate confidence intervals in normal infants, and thalamic NAA levels and Lac/NAA in infants with NE according to neurodevelopmental outcome. Areas under curves for thalamic NAA and Lac/NAA will be examined separately for early & late MRS. Accuracy of early MRS will inform utility of this investigation in decisions about withdrawal of life support; late MRS will inform about efficacy as a surrogate end point in clinical trials. Qualitative interviews will be thematically analysed and reported.