Detecting And Predicting Outcome In Term Neonates With Hypoxic-ischemic Encephalopathy: A Comparison Of Convention MRI, Diffusion-Weighted MR Imaging And Proton MR Spectroscopy

Objective: To prospectively evaluate CT, magnetic resonance (MR) imaging, hydrogen (~1H) MR spectroscopy, diffusion weighted imaging(DWI) and apparent diffusion coefficient (ADC) measurements for diagnosis and prediction of late neurologic outcome of HIE in term neonates in their earliest phase.Methods: Radiological examinations were performed in 38 term neonates with HIE with a 1.5 T MR scanner (GE Signa Hi-Speed). For conventional examinations, axial T1 weighted (TR/TE: 2200/11 msec) and T2 weighted (TR/TE: 6000/102 msec) sequences were obtained. DW imaging was obtained by using an echo planar imaging (EPI) sequence (b-value: 0. and 1000 s/mm~2). ~1H-MRS was obtained by using point-resolved spectroscopy sequence (PRESS) with the special volume at the left basal ganglia and thalami. All 32 patients (18boys, 14girls) that got the intelligence development and neurologic outcome after more than 6 months of birth were examined by conventional MR, DW imaging and MRS within the first 10 days of birth. And 15 control term infants without any asphyxia and with normal neurologic examination. All of them were examined by CT scan at the same day. The neonates were assigned to one of three groups according to their late outcome: those with an unfavorable outcome—that is, death or severe disability; those with a mild unfavorable outcome, and those with a favorable outcome. Clinical data, MR signal intensity abnormalities, ADCs, and ~1H-MR spectroscopy findings were compared by the analysis of variance to individualize the prognostic indicators. Data obtained in this study were analyzed with SPSS version 10.0.Results: DWI is more sensitive to detect the abnormality of deep white matter than conventional MRI and CT. But with the subcortical white matter and the hemorrhage, conventional MRI turns to have slight advantage. Among the late unfavorable group (n=5), the mild unfavorable group (n=9) and the favorable group (n=18), the late unfavorable neurologic outcome was associated with a mixed pattern of basal ganglia and posterior limb of the internal capsule (PLIC) signal intensity abnormalities on MR images. The unfavorable outcome was associated with the abnormal signal in basal ganglia or thalami or a lobe of brain or PLIC. ADCs in corona radiate, PLIC, thalami, lentiform nucleus and caudex cerebri were associated with the outcome, especially in corona radiate and PLIC. There were no significant differences between groups in anterior limb of internal capsule, deep parietal white matter, parietal gray matter, frontal gray matter, and cerebellum. In PLIC and caudex cerebri, ADCs were much lower in the group with neuromotor complaint than that without any neuromotor complaint. The ratios of metabolite in prognosis groupⅠand prognosis groupⅡdid not reach the statistical significance in comparison with the control group. The ratio of NAA/Cr in prognosis groupⅢwas significantly different from that in control group, the prognosis groupsⅠandⅡ. Besides, the ratio of NAA/Cho in prognosis groupⅢwas also a lot different between the control group and the prognosis groupⅠ. In addition, there were no significant differences between groups of the ratio of Cho/Cr and Lac/Cr. However, the X~2-test of Lac had the statistical significance.Conclusion: The abnormality of DWI, the change of ADC values, and the change of metabolite can reflect the injury degree of brain sensitively in the early phase of HIBD and can assess the prognosis of HIE at a certain extent. Especially, the decrease of ADCs in corona radiate and PLIC, as well as the reduction of NAA/C and NAA/Cho can evaluate the prognosis of HIBD efficaciously. The appearance of Lac may imply the unfavorable outcome. We suggest that the combination of DWI, ADCs and MRS can evaluate the prognosis of HIBD more efficaciously and exactly. Further studies on this case are still under way.