Spectroscopic imaging of stroke in humans: histopathology correlates of spectral changes.
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 begin 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.
Petroff
O A
OA
Department of Neurology, Yale University School of Medicine, New Haven, CT 06510.
Graham
G D
GD
Blamire
A M
AM
al-Rayess
M
M
Rothman
D L
DL
Fayad
P B
PB
Brass
L M
LM
Shulman
R G
RG
Prichard
J W
JW
D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D002452:Cell Count; D002561:Cerebrovascular Disorders / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed