The Value Of Diffusion Tensor MR Imaging In Evaluating Myelination And Prognosis Of Neonatal Hypoxic-ischemic Encephalopathy

Objective. To determine the utility of using quantitative diffusion isotropy and anisotropy values as an objective means of detection infants who suffered from hypoxic-ischemic encephalo(?)athy (HIE) in full-term neonatal period. In order to evaluate the follow-up value of DTI on full-term HIE and the affection of HIE on myelination and prognosis of the suffered infants.Materials and Methods. Conventional MR images and quantitative diffusion tensor MR images from 45 infants who had clinically diagnosed HIE before, including 20 cases of mild type, 16 cases of moderate type, 9 cases of severe type. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were calculated in predefined regions in the three groups. A one-way ANOVA(analysis of varriance) was performed to compare ADC and FA values among the groups for each region .ADC maps and color-coded FA maps and three-dimensional color-coded tensor maps were reconstructed to compare the mild group with other groups. Correlation analyse was performed among DTI with NBNA in neonatal period and clinic symptoms in infant period.Results. ADC values of the three groups were significantly different in regions of intresting (ROIs) : splenium of corpus callosum , posterior limb of internal capsule,corona radiate,front white matter,parietal white matter and putamina nuclei .while FA values were significantly different in the same ROIs except putamina nuclei . ADC values increased and FA values decreased by the order of ascending degree of HIE except putamina nuclei . ADC maps and color-coded FA maps were sensitive to show abnormal of white matters than conventional MRI images. From the different color on the images ,we can observed that ADC values increased by types of mild and moderate and severe HIE group, while FA values decreased by the same order. DTI correlated with NBNA in neonatal period and clinic symptoms in infantperiod (r=0.637, P=0.000; r=0.780P =0.000) .Conclusion. Quantitative diffusion tensor of isotropy and anisotropy values combined with ADC maps and color-coded FA maps can improve conspicuity than conventional MRI images and provide an obj'ective measure of hypoxic-ischemic injury on myelination of white matters. It correlates with NBNA in neonatal period and clinic symptoms in infant period. Calculation of isotropy and anisotropy values may provide a valuable marker index for the severity of hypoxic-ischemic injury and a predictor for prognosis.