Diffusion Weighted MR Imaging And Proton MR Spectroscopy In Term Neonates With Hypoxic-Ischemic Encephalopathy: Initial Experience

Objective: To determine the utility of using diffusion-weighted MR imaging(DWI) and quantitative apparent diffusion coefficient (ADC) values, proton magnetic resonance spectroscopy (¹H-MRI) for early detection of brain injury caused by hypoxic-ischemic encephalopathy (HIE) in term neonates.Methods: Conventional Magnetic Resonance Images (MRI), DWI (b=1000s/mm²) and ¹H-MRS were performed in 35 neonates (gestational age range, 37～42 wk; mean, 39.5 wk) with asphyxy and clinically diagnosed HIE which were divided into mild group(n=12), moderate group(n=15) and severe group(n=8) clinically. The mean age of them is 5.1 days, range from 2-12 days. Fifteen term neonates (gestational age range, 37-42 wk, mean, 39.3 wk; age range, 1-12 days, mean, 5.7 days) without HIE served as control group. All neonates were scaned with GE Signa Hi-Speed 1.5T MRI scanner. T₁-Flair, T₂-FRFSE sequence, SE-EPI sequence and point-resolved spectroscopy sequence (PRESS) sequence were used for conventional MRI, DWI and ¹H-MRS. All data was processed by functool in GE Advantage workstation AW4.0₀5. The cortex and subcortical white matter, deep white matter, basal ganglia and thalami etc were observed with DWI and conventional MRI. ADC values were calculated in 12 predefines regions, including corona radiate, the posterior limb of the internal capsule (PLIC), thalami, etc, and were compared between groups. The spectral volume of interest was in the left basal ganglia and thalami (BGT). The ratios of N-acetylaspartate/choline (NAA/Cho), NAA/cretine (NAA/Cr), Cho/Cr, lactate/Cho (Lac/Cho) and Lac/Cr were measured. Statistical analysis was accessed by SPSS 10.0. A P value of <0.05 was considered to indicate a statistically significant difference. Results: It's more easily to detect the abnormality of deep white matter (WM) by using DWI than conventional MRI. But when comes to the cortex and subcortical white matter and the slight haemorrhage, conventional MRI has slight advantage. The difference of ADC values in all regions between mild HIE group and control subjects didn't reach statistically significant. ADC values in patients with moderate HIE were significantly different from those of control subjects in the posterior limb of the internal capsule (PLIC) and corona radiate (P=0.003 and P=0.001). ADC values in patients with severe HIE were significantly different in PLIC, corona radiate, thalami,...