Figure 7.

Newborn hypoxic/ischemic injury. Typical MR spectra of the thalamus of acute mild newborn hypoxic/ischemic injury (HIE) with clinically unremarkable follow up (A,C) versus severe HIE followed by death or significant disability (B,D). Note that spectra (A) + (B) were acquired with a short echo time (TE = 35 ms), whereas spectra (C) + (D) were acquired with long TE = 288 ms. Metabolic markers of severe injury that have been consistently reported in the literature are elevated lactate (Lac) and lipids, reduced NAA, and elevated glutamine (Gln). The above spectra were scaled to the approximate absolute metabolite levels ((A) vs. (B) and (C) vs. (D)). Edema formation and/or cell death and depletion of intracellular metabolites in severe HIE may explain generally lower absolute concentrations. In long-TE spectra, signals from lipid, glutamate, and glutamine are suppressed resulting in a more unambiguous detection and quantitation of NAA and lactate, which may simplify the determination of the important Lac/NAA ratio. Spectra were acquired within 1 week of injury on a clinical 3T scanner with SV-PRESS, TR = 2 s, and TE as indicated above.