Sodium mapping in focal cerebral ischemia in the rat by quantitative (23)Na MRI.
OBJECTIVE
To validate (23)Na twisted projection magnetic resonance imaging (MRI) as a quantitative technique to assess local brain sodium concentration ([Na(+)](br)) during rat focal ischemia every 5.3 minutes.


METHODS
The MRI protocol included an ultrashort echo-time (0.4 msec), a correction of radiofrequency (RF) inhomogeneities by B(1) mapping, and the use of 0-154 mM NaCl calibration standards. To compare MRI [Na(+)](br) values with those obtained by emission flame photometry in precision-punched brain samples of about 0.5 mm(3) size, MR images were aligned with a histological three-dimensional reconstruction of the punched brain and regions of interest (ROIs) were placed precisely over the punch voids.


RESULTS
The Bland-Altman analysis of [Na(+)](br) in normal and ischemic cortex and caudate putamen of seven rats quantitated by (23)Na MRI and flame photometry yielded a mean bias and limits of agreement (at +/-1.96 SD) of 2% and 43% of average, respectively. A linear increase in [Na(+)](br) was observed between 1 and 6 hours after middle cerebral artery occlusion.


CONCLUSIONS
(23)Na MRI provides accurate and reliable results within the whole range of [Na(+)](br) in ischemia with a temporal resolution of 5.3 minutes and precisely targeted submicroliter ROIs in selected brain structures.
Yushmanov
Victor E
VE
Department of Anesthesiology, Allegheny-Singer Research Institute, Pittsburgh, Pennsylvania, USA. vyushman@wpahs.org
Yanovski
Boris
B
Kharlamov
Alexander
A
LaVerde
George
G
Boada
Fernando E
FE
Jones
Stephen C
SC
D000818:Animals; D002545:Brain Ischemia / Q000175:diagnosis* / Q000473:pathology; D004195:Disease Models, Animal; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000737:chemistry; D013997:Time Factors
D012964:Sodium