Characterization of Cerebral White Matter Damage in Preterm Infants Using 1H and 31P Magnetic Resonance Spectroscopy

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Abstract
The biochemical characteristics of white matter damage (WMD) in preterm infants were assessed using magnetic resonance spectroscopy (MRS). The authors hypothesized that preterm infants with WMD at term had a persisting cerebral lactic alkalosis and reduced N-acetyl aspartate (NAA)/creatine plus phosphocreatine (Cr), similar to that previously documented in term infants weeks after perinatal hypoxia–ischemia (HI). Thirty infants (gestational age 27.9 ± 3.1 weeks, birth weight 1122 ± 445 g) were studied at postnatal age of 9.8 ± 4.1 weeks (corrected age 40.3 ± 3.9 weeks). Infants were grouped according to the presence or absence of WMD on magnetic resonance (MR) images. The peak area ratios of lactate/Cr, NAA/Cr, myo-inositol/Cr, and choline (Cho)/Cr were measured from an 8-cm3 voxel in the posterior periventricular white matter (WM) using proton MRS. Intracellular pH (pHi) was calculated using phosphorus MRS. Eighteen infants had normal WM on MR imaging; 12 had WMD. For infants with WMD, lactate/Cr and myo-inositol/Cr were related ( P < 0.01); lactate/Cr and pHi were not ( P = 0.8). In the WMD group, mean lactate/Cr and myo-inositol/Cr were higher ( P < 0.001, P < 0.05, respectively) than the normal WM group. There was no difference in the NAA/Cr, Cho/Cr, or pHi between the two groups, although pHi was not measured in all infants. These findings suggest that WMD in the preterm infant at term has a different biochemical profile compared with the term infant after perinatal HI.