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

• Published in: Journal of magnetic resonance imaging 2009-04, Vol.29 (4), p.962-966
• Main Authors: Yushmanov, Victor E, Yanovski, Boris, Kharlamov, Alexander, LaVerde, George, Boada, Fernando E, Jones, Stephen C
• Format: Article
• Language: English
• Subjects: Animals; Brain Ischemia - diagnosis; Brain Ischemia - pathology; Disease Models, Animal; Magnetic Resonance Imaging - methods; Male; Rats; Rats, Sprague-Dawley; Sodium - chemistry; Time Factors
• ISSN: 1053-1807
• DOI: 10.1002/jmri.21643

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. 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. 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. (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.