Premium
Monitoring of brain potassium with rubidium flame photometry and MRI
Author(s) -
Yushmanov Victor E.,
Kharlamov Alexander,
Boada Fernando E.,
Jones Stephen C.
Publication year - 2007
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.21155
Subject(s) - flame photometry , rubidium , ischemia , potassium , chemistry , nuclear medicine , magnetic resonance imaging , cortex (anatomy) , nuclear magnetic resonance , medicine , physics , radiology , biology , neuroscience , organic chemistry
An animal model was developed to monitor [K + ] in the brain using partial K + replacement with Rb + and 87 Rb MRI. Fifty‐one rats were given 0–80 mM of RbCl in the drinking water for up to 90 days. Focal cerebral ischemia was produced in 15 of the animals. Na, K, and Rb content in precision‐guided submilligram samples of cortical brain were determined by emission flame photometry. Multinuclear 87 Rb/ 23 Na/ 1 H MRI was performed on phantoms and rats at 3T using a twisted projection imaging (TPI) scheme for 87 Rb/ 23 Na, and custom‐built surface or parallel cosine transmit/receive coils. Brain [Rb + ] was safely brought up to 17–25 mEq/kg within 2–3 weeks of feeding. The characteristic patterns of [K + ] decrease (with a sharp drop at 3–4 hr of ischemia) and [Na + ] increase (at a rate of 31%/hr) observed previously in animals without Rb/K substitution were reproduced in ischemic cortex. The Rb/(Rb+K) ratio increased over time in ischemic areas (R = 0.91, P < 0.001), suggesting an additional index of ischemia progression. Preliminary 87 Rb MRI gave an estimate of 20–25 mEq Rb/kg brain weight ( N = 2). In conclusion, brain Rb + is detectable by 87 Rb MRI and does not significantly interfere with ion dynamics in ischemic brain, which enables 87 Rb MRI studies of K + in ischemia. Magn Reson Med 57:494–500, 2007. © 2007 Wiley‐Liss, Inc.