Estimating Intracellular Lithium in Brain in Vivo by Lithium-7 MRS
Pearce J, Komoroski R
University of Arkansas for Medical Sciences
The fraction of intracellular lithium (Li) in the brain for subjects under treatment for bipolar disorder is not known. Localized 7Li MRS can measure the total Li concentration in brain in vivo. Biexponential 7Li T2s in rat brain in vivo were measured so as to estimate the Li compartmental distribution. These biexponential T2 results were also used for estimating Li compartmental distribution from previously determined monoexponential T2 decays by a simple linear approximation. Unlike for Na, a substantial fraction of Li enters the cell. Depending on estimation method, an average % intracellular Li of 49-63% was found.