Magnetic resonance spectroscopy in hypoxic-ischemic encephalopathy.

In vivo magnetic resonance spectroscopy (MRS) allows repetitive, noninvasive measurement of cerebral metabolites, including ATP, phosphocreatine (PCr), inorganic phosphate (Pi), intracellular pH, lactate, and N-acetyl aspartate. MRS has been used extensively to study cerebral metabolic changes in neonatal neurologic disorders. In babies with severe hypoxic-ischemic encephalopathy, PCr decreases and Pi increases, causing a fall in PCr/Pi and PCr/ATP, and a rise in Pi/ATP. These changes correlate with neurodevelopmental outcome. Decreased ATP is only seen in extremely severe hypoxic-ischemic encephalopathy and is usually associated with death in the neonatal period. Serial MRS studies may be helpful in selecting babies who would benefit from interventional treatment. Ongoing advances in MRS technology will permit localized, multinuclear spectroscopy, improving our ability to identify cerebral metabolic changes.