Sodium mapping in focal cerebral ischemia in the rat by quantitative 23Na MRI

✍ Scribed by Victor E. Yushmanov; Boris Yanovski; Alexander Kharlamov; George LaVerde; Fernando E. Boada; Stephen C. Jones

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 430 KB
• Volume: 29
• Category: Article
• ISSN: 1053-1807
• DOI: 10.1002/jmri.21643

✦ Synopsis

Abstract

Purpose

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.

Materials and 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.

Conclusion

^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. J. Magn. Reson. Imaging 2009;29:962–966. © 2009 Wiley‐Liss, Inc.