Characterization of cerebral white matter damage in preterm infants using H-1 and P-31 magnetic resonance spectroscopy

The biochemical characteristics of white matter damage (WMD) in preterm inf ants were assessed using magnetic resonance spectroscopy (MRS). The authors hypothesized that preterm infants with WMD at term had a persisting cerebr al lactic alkalosis and reduced N-acetyl aspartate (NAA)/ creatine plus pho sphocreatine (Cr), similar to that previously documented in term infants we eks 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 +/- 39 weeks). Infants were gr ouped 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-cm(3) voxel in the posterior periv entricular white matter (WM) using proton MRS. Intracellular pH (pH(i)) was calculated using phosphorus MRS. Eighteen infants hall normal WM on MR ima ging; 12 had WMD. For infants with WMD, lactate/Cr and myo-inositol/Cr were related (P < 0.01); lactate/Cr and pH, were not (P = 0.8). In the WMD grou p, mean lactate/Cr and myo-inositol/Cr were higher (P < 0.001, P < 0.05, re spectively) than the normal WM group. There was no difference in the NAA/Cr , Cho/Cr, or pH, between the two groups, although pH(i) 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 pe rinatal HI.