MR spectroscopy in stroke.

Magnetic resonance spectroscopy (MRS) is a non-invasive in vivo method that allows the investigation of biochemical changes in both animals and humans. The application of MRS to the study of stroke has made possible dynamic studies of intracellular metabolism of cerebral ischaemia. The majority of the stroke studies have been carried out using proton [1H]-MRS which allows the detection of N-acetyl aspartate (NAA), a neuronal marker. [1H]-MRS changes in humans demonstrate that after an infarct, lactate appears, while NAA and total creatine are reduced compared to the contralateral hemisphere. Longitudinal studies demonstrate a further reduction of NAA suggesting that ischaemic injury continues for more than a week following infarction. Major advances in the treatment of acute stroke require the accurate prediction of the mortality of stroke patients. Patients with large infarcts are known to do badly. In patients with small infarcts, less than 80 cm3, the addition of core NAA concentrations and cerebral blood flow have enabled the identification of some of the patients likely to benefit from new drug treatment.