Proton magnetic resonance spectroscopy in neonates with hypoxic-ischemic injury and its prognostic value

Abstract

It is difficult to predict the neurologic outcome of neonates with hypoxic-ischemic encephalopathy (HIE). Our goal was to investigate the prognostic values of magnetic resonance spectroscopy (MRS) in neonatal HIE. During this study, 46 neonates with HIE underwent magnetic resonance imaging (MRI) and proton MRS ((1)HMRS). The sample included 25 cases of mild HIE, 11 cases of moderate HIE, and 10 cases of severe HIE. Nine healthy neonates without asphyxia served as controls. (1)HMRS techniques included single-voxel MRS and 2-D-point-resolved spatially localized spectroscopy (PRESS) multivoxel chemical shift spectroscopy imaging. Then, 31 of 46 neonates with HIE were divided into 3 groups according to their prognosis: dead, abnormal, and normal outcome. Abnormal and normal outcome were defined by follow-up MRI. Metabolic changes were analyzed and compared with HIE grading and prognosis. As a result, the GLx-alpha peak was markedly increased in the moderate and severe HIE groups. The GLx-alpha/Cr ratio in the control, mild, moderate, and severe HIE groups was 0.18, 0.21, 0.64, 1.31, respectively. The Lac/Cr ratio was 0.12, 0.14, 0.19, and 0.26, respectively. A Spearman rank correlation test confirmed that the ratio of GLx-alpha/Cr and Lac/Cr had significant positive correlation with clinical grading of HIE (P < 0.01). The GLx-alpha/Cr ratio in the dead, abnormal, and normal outcome groups was 1.28, 0.82, and 0.25, respectively; the Lac/Cr ratio was 0.34, 0.19, and 0.14, respectively. An anaylsis of variance demonstrated that the differences were significant (both P < 0.01). A Spearman rank correlation test confirmed that the ratio of GLx-alpha/Cr and Lac/Cr had significant negative correlation with prognosis of HIE; GLx-alpha/Cr showed a much stronger correlation than the Lac/Cr ratio (P < 0.01). The formula of the relationship between the poor prognosis of HIE and the ratio of GLx-alpha/Cr in basal ganglia was established by the logistic regression model. In conclusion, (1)HMRS is a useful tool for evaluating the severity and prognosis of HIE. The higher ratio of GLx-alpha/Cr in the basal ganglia and thalamus may predict a poor outcome in neonates with HIE.