651 - Diffusion-Tensor Imaging and Neurodevelopmental Outcomes in Neonates with Hypoxic-Ischemic Encephalopathy treated with Therapeutic Hypothermia

Maria Jose Castro Gomez, McGill University Faculty of Medicine and Health Sciences, Montreal, PQ, Canada; Hossein Jomleh, McGill University Faculty of Medicine and Health Sciences, Montréal, PQ, Canada; Emmanouil Rampakakis, McGill University Faculty of Medicine and Health Sciences, Montreal, PQ, Canada; Guillaume Gilbert, Philips Healthcare, Mississauga, ON, Canada; Pia Wintermark, McGill University, Montreal, PQ, Canada

Background: Birth asphyxia leading to hypoxic-ischemic encephalopathy (HIE) can cause brain injuries and long-term neurodevelopmental impairments. Therapeutic hypothermia (TH) is the standard treatment, but up to 29% of treated neonates still develop brain injuries and neurological sequelae. Magnetic resonance imaging (MRI) and diffusion-tensor imaging (DTI), which assesses brain microstructure, have been used to study brain injury in neonates with HIE. DTI may help evaluate the relationship between brain microstructure and neurodevelopmental outcomes in HIE neonates treated with TH.

Objective: To investigate the association between DTI metrics and neurodevelopmental outcomes in neonates with HIE treated with TH.

Design/Methods: We conducted a prospective neuroimaging study on neonates with HIE treated with TH, comparing those without adverse outcome at 2 years (noAO) to those with adverse outcome (AO). Neurodevelopmental outcomes, including cerebral palsy (CP), global developmental delay (GDD), and epilepsy, were assessed at 2 years, a critical time-point for diagnosing CP and evaluating long-term outcomes. Brain MRIs were performed around days 2, 10, and 30 of life, and fractional anisotropy (FA) and the apparent diffusion coefficient (ADC) values were measured in seven regions of interest (ROIs), mainly, the posterior limb of the internal capsule (PLIC), thalamus, lentiform nuclei, anterior/posterior white matter, genu and splenium of the corpus callosum. Separate generalized linear models were used to compare DTI metrics between the groups, adjusting for gestational age and MRI time-point.

Results: Eighty-one participants (49 noAO and 32 AO) were scanned in the first month of life, with a total of 154 MRI scans performed at different time points. On day 2, FA values did not differ between the groups. However, by days 10 and 30, FA values were significantly lower in AO neonates in the PLIC, thalamus, lentiform nuclei, anterior white matter, and splenium of the corpus callosum. FA values in the genu of the corpus callosum were decreased on day 10 but were not different by day 30, while the posterior white matter showed FA reduction by day 30. ADC values did not significantly differ between groups across time points.

Conclusion(s): Microstructural impairments, as assessed by DTI, during the first month of life were associated with 2-year adverse neurodevelopmental outcomes in HIE-TH neonates. Furthermore, FA measurements can detect subtle microstructural changes associated with adverse outcomes that may not be visible on conventional imaging.

Figure 1.
Fractional Anisotropy (FA) and Apparent Diffusion Coefficient (ADC) values over time in the Posterior Limb of the Internal Capsule (PLIC) (A, C) and the Anterior White Matter (B, D) respectively. FA values were decreased on days 10 and 30 in both ROIs in the neonates with HIE with adverse outcomes (AO) at 2-year follow-up. ADC values did not significantly differ between groups across time points. Significance: * p ≤ 0.05, ** p ≤ 0.01, *** p ≤ 0.001.