Diffusion tensor imaging and MR spectroscopy in the evaluation of neonatal encephalopathies

BackgroundNeonatal encephalopathy is a broad term encompassing many underlying pathologies, most commonly hypoxic-ischemic encephalopathy. Though this diagnosis has long been derived from relevant history, examination and lab parameters, this study aims to illustrate the diagnostic power of advanced radiological techniques such as MR Spectroscopy and Diffusion Tensor Imaging to objectively classify subjects based on disease severity and predict adverse outcomes.Methods41 cases of neonatal encephalopathy with MRI Brain were included in the study. NAA/Cr, NAA/Cho, Cho/Cr and Lac/Cr ratios in basal ganglia and white matter, and DTI parameters of FA, ADC and MD in five major tracts were recorded. Developmental milestones were assessed on follow up of the child at 6 months. Correlation of the MRS and DTI values with disease severity and status at follow up was done.ResultsThe ratios of NAA/Cr and Lac/Cr in basal ganglia and white matter showed strong positive correlation with the disease severity at onset. Lac/Cr also positively correlated with the abnormal outcome group. FA values in the posterior limbs of internal capsule, thalami and corpus callosum were seen to most consistently correlate with the abnormal outcome group, substantiating these objective and reproducible metrics that can be employed for neuro-prognostication across all etiologies of neonatal encephalopathy.ConclusionNeonatal encephalopathy is an umbrella term for conditions that can cause devastating neurological sequelae, which necessitates radiological pattern recognition for identification of etiology, and use of supplementary quantitative techniques such as MRS and DTI is endorsed for objective evaluation of clinical outcomes.