Inhomogeneous sodium accumulation in the ischemic core in rat focal cerebral ischemia by 23Na MRI.
OBJECTIVE
To test the hypotheses that (i) the regional heterogeneity of brain sodium concentration ([Na(+)](br)) provides a parameter for ischemic progression not available from apparent diffusion coefficient (ADC) data, and (ii) [Na(+)](br) increases more in ischemic cortex than in the caudate putamen (CP) with its lesser collateral circulation after middle cerebral artery occlusion in the rat.


METHODS
(23)Na twisted projection MRI was performed at 3 Tesla. [Na(+)](br) was independently determined by flame photometry. The ischemic core was localized by ADC, by microtubule-associated protein-2 immunohistochemistry, and by changes in surface reflectivity.


RESULTS
Within the ischemic core, the ADC ratio relative to the contralateral tissue was homogeneous (0.63 +/- 0.07), whereas the rate of [Na(+)](br) increase (slope) was heterogeneous (P < 0.005): 22 +/- 4%/h in the sites of maximum slope versus 14 +/- 1%/h elsewhere (here 100% is [Na(+)](br) in the contralateral brain). Maximum slopes in the cortex were higher than in CP (P < 0.05). In the ischemic regions, there was no slope/ADC correlation between animals and within the same brain (P > 0.1). Maximum slope was located at the periphery of ischemic core in 8/10 animals.


CONCLUSIONS
Unlike ADC, (23)Na MRI detected within-core ischemic lesion heterogeneity.
Yushmanov
Victor E
VE
Department of Anesthesiology, Allegheny-Singer Research Institute, Pittsburgh, Pennsylvania 15212-4772, USA. vyushman@wpahs.org
Kharlamov
Alexander
A
Yanovski
Boris
B
LaVerde
George
G
Boada
Fernando E
FE
Jones
Stephen C
SC
D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D002545:Brain Ischemia / Q000378:metabolism*; D001931:Brain Mapping / Q000379:methods; D004195:Disease Models, Animal; D018450:Disease Progression; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010783:Photometry; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000378:metabolism*; D012975:Sodium Isotopes / Q000378:metabolism
D015415:Biomarkers; D012975:Sodium Isotopes; D012964:Sodium