Apparent diffusion coefficient in quantitative analysis of brain injury in term neonates with hypoxic-ischemic encephalopathy

Abstract

Objective Applying diffusion weighted image (DWI) and apparent diffusion coefficient (ADC) to analyze brain injury caused by hypoxic-ischemic encephalopathy (HIE) in term neonates.Methods From June 1,2010 to January 5,2011,thirty-eight full term neonates with HIE were hospitalized in the Second Hospital of Tianjin Medical University.Those with nervous system diseases were excluded.The 38 cases were divided to mild HIE group (n=24) and moderate-to-severe HIE group (n=14).The control group included 10 normal full term neonates without history of asphyxia.All babies were scanned by magnetic resonance imaging (MRI).Spin echo-echo planar imaging sequence was used for DWI images.ADC values of nine regions (frontal lobe gray matter,frontal white matter,parietal gray matter,parietal white matter,corona radiata,caudate nucleus,putamen,posterior limb of the internal capsule and thalamus) were measured.MRI and DWI images were compared.ADC values were compared by analysis of variance and Student-Newman-Keuls test.Results ADC values of the nine indicated regions (frontal lobe gray matter,frontal white matter,parietal gray matter,parietal white matter,corona radiata,caudate nucleus,putamen,posterior limb of the internal capsule and thalamus) were (1.37±0.07),(1.81±0.12),(1.35±0.10),(1.84±0.09),(1.23±0.11),(1.28±0.09),(1.18±0.08),(1.05±0.07) and (1.15±0.08) ×10-3 mm2/s in control group,(1.28±0.11),(1.60±0.15),(1.27±0.09),(1.59±0.20),(1.19±0.15),(1.19±0.13),(1.11±0.09),(0.97±0.11) and (1.06±0.12) ×10-3 mm2/s in mild HIE group,and (1.18±0.14),(1.51±0.22),(1.19±0.09),(1.56±0.19),(1.03±0.16),(1.08±0.07),(1.02±0.07),(0.87±0.09) and (0.96±0.12) × 10-3 mm2/s in moderate-to-severe HIE group.ADC values among the three groups had statistical difference (F=3.89,3.21,4.05,3.30,3.28,3.27,4.12,4.75and 4.72,all P＜0.05).ADC values of frontal lobe gray matter,frontal white matter,parietal gray matter,parietal white matter,putamen,posterior limb of the internal capsule and thalamus in mild HIE group were lower than those in control group (all P＜0.05).All of the ADC values of nine regions in moderate-to-severe HIE group were lower than those in control group (all P＜0.05).ADC value of frontal lobe gray matter,parietal gray matter,corona radiata,caudate nucleus,putamen,posterior limb of the internal capsule and thalamus in moderate-to-severe HIE group were lower than those in mild HIE group (all P＜0.05).Conclusion DWI and ADC values could reflect brain injury caused by HIE,and ADC values can be used to quantitatively analyze the degree of hypoxic-ischemic injury. Key words: Hypoxia-ischemia, brain; Infant, newborn; Diffusion magnetic resonance imaging