OBJECTIVETo elucidate that diffusion weighted imaging (DWI) can be used to predict the injured regions of neonatal brain with hypoxic-ischemic encephalopathy (HIE) in the early phase of injury, and to measure the apparent diffusion coefficient (ADC) values in the multiple regions of the brain.

METHODThe participants in this study were twenty-six infants with HIE from neonatology ward hospitalized between July 2006 and July 2009. Nineteen patients had severe HIE, and seven had moderate HIE. DWI and conventional magnetic resonance imaging (MRI) were performed for each case within the first 72 hrs. The ADC values of eight regions of interest (ROIs) were measured in ten cases with severe HIE (ADC values group). ROIs included posterior limb of internal capsule (PLIC), ventrolateral thalami, basal ganglia, perirolandic cortex, occipital cortex, centrum semiovale, brainstem, and frontal white matter. Twelve neonates were enrolled as the control subjects.

RESULTSDuring the first 72 hrs, the conventional MRI of 26 patients showed subarachnoid hemorrhage in 5, subdural hemorrhage in 2, and mild high signal intensity in the cortex of only one patient. In the 19 cases with severe HIE, abnormal signal intensities were seen in ventrolateral thalami and perirolandic cortex of 17 patients (89%), and the remaining 2 infants showed abnormal cortex and subcortical white matter. In 7 cases with moderate HIE, 4 had abnormal signal intensity in the cortex and subcortical white matter, 2 had abnormal periventricular white matter, and only one showed abnormal signal intensity in the ventrolateral thalami and perirolandic cortex. In the ADC values group, the average ADC values of posterior limb of internal capsule (PLIC), ventrolateral thalami, basal ganglia, perirolandic cortex, occipital cortex, centrum semiovale, brainstem, and frontal white matter respectively were 0.68 (0.56 - 0.88), 0.73 ± 0.13, 0.67 ± 0.11, 0.78 ± 0.22, 0.90 ± 0.16, 0.87 ± 0.21, 0.73 ± 0.19, 1.32 ± 0.22 × 10(-3) mm(2)/S. In the control group, the average ADC values of posterior limb of internal capsule (PLIC), ventrolateral thalami, basal ganglia, perirolandic cortex, occipital cortex, centrum semiovale, brainstem, and frontal white matter respectively were 0.96 (0.95 - 1.02), 1.02 ± 0.90, 1.15 ± 0.99, 1.08 ± 0.07, 1.09 ± 0.08, 1.39 ± 0.20, 0.96 ± 0.05, 1.58 ± 0.18× 10(-3) mm(2)/S. There was statistically significant difference in the average ADC values between each of 8 ROIs of infants with HIE and healthy neonates (P < 0.01).

CONCLUSIONIn the first days after birth, the major injured regions of severe HIE were ventrolateral thalami and perirolandic cortex, the minor injured regions were cortex and subcortical white matter. Multiple regions of moderate HIE were injured, including cortex with subcortical white matter, periventricular white matter, and ventrolateral thalami with perirolandic cortex. The ADC values of the regions with abnormal signal intensity decreased, also some regions with the normal signal intensity.