Spectroscopic imaging of stroke in humans: histopathology correlates of spectral changes
Petroff, O.A.; Graham, G.D.; Blamire, A.M.; al-Rayess, M.; Rothman, D.L.; Fayad, P.B.; Brass, L.M.; Shulman, R.G.; Prichard, J.W.
Neurology 42(7): 1349-1354
1992
ISSN/ISBN: 0028-3878 PMID: 1620345 Document Number: 390084
Previous studies of human stroke by 1H nuclear magnetic resonance spectroscopy have shown elevation of lactate lasting 3 to 6 months. Complete metabolic turnover of the elevated lactate pool has been demonstrated 5 weeks after a stroke. Its cellular localization is among the first questions requiring clarification. Information pertinent to this question came to us from a patient with a 2-week-old stroke by 1H nuclear magnetic resonance spectroscopic imaging 1 week before his death led to neuropathologic examination of the brain. 1H spectra from voxels including the infarcts showed increased lactate and decreased N-acetylaspartate. Histopathology showed sheets of foamy macrophages in the infarct, but few neurons. Macrophage density ranged from 196 cells/mm2 near the surface of the infarct to 788 near its medial margin. Glial density was 500 to 800 cells/mm2. Lactate concentration in voxels including portions of the infarct was estimated at 7 to 14 mM. Voxels showing low N-acetylaspartate and high lactate on spectroscopic imaging were associated with histopathologic sections containing foamy macrophages. Brain macrophages-which began to appear 3 days after infarction and gradually disappear over several months - could be a major source of elevated lactate signals that persist for months after stroke.