Correlation of basal ganglia magnetic resonance spectroscopy with apgar score in perinatal asphyxia

Background: Brain metabolite levels are measured by proton magnetic resonan ce spectroscopy (H-1 MRS) and include N-acetylaspartate (NAA), creatine (Cr ), choline (Cho),and lactate and the ratios NAA to Cho and Cr (NAA-ChoCr), NAA-Cr, NAA-Cho, and Cho-Cr. Brain metabolite levels may correlate with the degree of neonatal asphyxia. Objective: To determine which brain metabolite ratios have the strongest co rrelation with the Apgar scores in infants with possible asphyxia; whether the correlation is stronger with basal ganglia (BG) or anterior border-zone metabolites; and whether a combined approach using routine MR imaging (MRI ), diffusion-weighted MRI, and MRS can be used to evaluate the severity of neonatal asphyxia. Methods: Twenty infants with 1-minute Apgar scores of 6 or less were studie d at 2 to 28 days of age. The MRS variables were compared with routine and diffusion-weighted brain MRI. Clinical variables and MRS findings were subj ected to factor analysis and stepwise multiple regressions to determine int errelationships. Results: The BG region NAA-Cho and ChoCr ratios correlated with the 1-minut e (P < .001) and 5-minute (P = .01 for NAA-Cho; P = .006 for NAA-ChoCr). Th ere was no correlation between metabolite levels and the 10-minute Apgar sc ores. The strongest predictions exist between the 1-minute Apgar scores and the NAA-Cho and NAA-ChoCr ratios. In the anterior border zone, the only co rrelation was between the 1-minute Apgar score and the NAA-Cho ratio, but t here was a strong age effect in these data. Lactate was found in the BG of 3 infants, all of whom had 5-minute Apgar scores of 6 or less. Three patien ts had focal lesions on MRI; 2 of these had elevated lactate levels in the abnormal region; and the third, who had an intrauterine stroke, had no lact ate in the region. Conclusions: Correlations between NAA-Cho and NAA-ChoCr ratios and the 1- a nd 5-minute Apgar scores are stronger in the BG region than in the frontal border zone. The presence or absence of lactate may indicate the severity o f the brain insult, and the combination of MRS, MRI, and diffusion-weighted MRI may assist in localizing and predicting a long-term brain injury.