Objective To evaluate apparent diffusion coefficient (ADC), measured in specific infratentorial brain structures in the first weeks of life, as prognostic indicator of neuromotor outcome for HIE neonates both treated and not with whole-body hypothermia (TH).

Methods We retrospectively evaluated 71 MRI studies of term neonates, born between 2010 and 2013 at Boston Children’s Hospital. Selected cases were classified into three groups: 1) HIE neonates who underwent TH, 2) HIE normothermics (TN), and 3) controls. The neuromotor outcome was categorised as normal, abnormal and death. The ADCmean was calculated for six infratentorial brain regions.

Results 51 infants were included: 29 HIE TH treated, 11 HIE TN, and 11 controls (mean gestational age of 39.07 weeks; 62% male; 11.7% non-survivors). Mean age at first MRI was 3.6 days (range, 1–14 days). Statistically significant correlation was shown between motor outcome and the ADC mean in the vermis (p = 0.002), cerebellar left hemisphere (p = 0.035), midbrain (p = 0.028), and pons (p = 0.008). In patients treated with TH, only in the vermis did ADC mean remained significantly lower than controls (p = 0.03). There were significant correlation between infant survival and ADC mean in all ROIs except the pons and medulla.

Conclusions ADC mean values during the first week of life in vermis, cerebellar left hemisphere, midbrain and pons are correlated with the motor outcome in infants with HIE. Therefore, this objective tool could be used to detect particularly severe cases of HIE for assessing prognosis at the first week of life.