Increased detectability of alpha brain glutamate/glutamine in neonatal hypoxic-ischemic encephalopathy

BACKGROUND AND PURPOSE: Proton MR spectroscopy (MRS) detectability of brain glutamate/glutamine (Glx) is increased in hypoxic-ischemic insults and is implicated in the neuronal injury and death that follows. Our aim was to co rrelate the proton MRS detectability of alpha-CH protons of Glx (alpha-Glx) with the Sarnat stage of neonatal hypoxic-ischemic encephalopathy (HIE). METHODS: Initial and follow-up proton MRS studies at 1.9 T were performed i n 28 neonates aged 1 to 7 days (seven healthy control subjects and 21 with HIE: 10 mild, nine moderate, and two severe) and in 12 neonates aged 13 to 17 days (12 with HIE: eight mild, three moderate, and one severe), respecti vely. Both point-resolved spectroscopy (PRESS) and stimulated-echo acquisit ion mode (STEAM) sequences were used, The spectral volume of interest was i n the basal ganglia, thalami, and adjoining regions. The detectability of a lpha-Glx was assessed by two different parameters: the detection rate of th e a-Glx peak and the peak-area ratio of alpha-Glx to creatine and phosphocr eatine. RESULTS: On both the initial and follow-up PRESS studies, all the neonates with moderate and severe HIE showed an a-Glx peak, compared with one health y control subject in the initial study and one neonate with mild HIE in bot h the studies. They also demonstrated a significantly higher peak-area rati o of alpha-Glx/(creatine and phosphocreatine) on both the initial and follo wup studies. The peak-area ratios in neonates with HIE positively correlate d with the Sarnat stage of HIE on both the initial and follow-up studies. N eonates with moderate and severe HIE also showed a consistently higher alph a-Glx peak on both the initial and follow-up studies with the STEAM sequenc e. CONCLUSION: Proton MRS detectability of alpha-Glx is increased in moderate and severe HIE and correlates with the Sarnat stage of HIE.