Quantitative lithium magnetic resonance spectroscopy in the normal human brain on a 3 T clinical scanner

Abstract

Lithium (Li) is a core for many neuropsychiatric conditions. The safe serum range of Li treatment is narrow, and regular monitoring by blood test is required, although serum levels are thought to be a poor indicator of Li concentration in the brain itself. Brain Li concentration can be measured by magnetic resonance spectroscopy. However, little data exist in the healthy human brain, and there are no studies of the relaxation properties of brain 7 Li at 3 T. Here, 11 healthy male subjects were prescribed Li over a period of 11 days. In seven subjects, the in vivo T 1 of 7 Li was measured to be 2.1 6 0.7 s. In the remaining subjects, spectroscopic imaging (1D) yielded a mean brain 7 Li concentration of 0.71 6 0.1 mM, with no significant difference between gray and white matter. Mean serum concentration was 0.9 6 0.16 mM, giving a mean brain/ serum ratio of 0.78 6 0.26. Magn Reson Med 66:945-949,

Accumulation of Lithium in the Hippocampus of Patients With Bipolar Disorder: A Lithium-7 Magnetic Resonance Imaging Study at 7 Tesla

“…By exploiting the experimental T 1 and T 2 relaxation times of 7 Li in a subset of patients with BD, [Li] maps were established. Those global monoexponential T 1,mono and T 2,mono values were well within the range of previous reports (20,22,48). It is of interest to note here that the use of an SSFP sequence with an ultra-short TE minimizes the T 2 * weighting and reduces sensibly the T 2 weighting of the 7 Li image than a balanced SSFP sequence (28).…”

“…It is at this point that nuclear magnetic resonance (NMR) provides a unique solution to detect and quantify in a noninvasive manner the local concentration of Li ([Li]). Indeed, Lithium-7 ( 7 Li), the most abundant stable Li isotope, possesses a good NMR sensitivity (w29% of 1 H), and its detection using in vivo 7 Li NMR spectroscopy has been performed successfully in animal models as well as in humans (19)(20)(21). More recently, 7 Li NMR spectroscopic imaging (22)(23)(24)(25) and magnetic resonance imaging (MRI) (26)(27)(28) have been applied for the noninvasive determination of brain Li distribution in patients with BD.…”

4‐T 7Li 3D MR spectroscopy imaging in the brains of bipolar disorder subjects

“…Two early MRS imaging (MRSI) studies were performed on a clinical scanner, both at the relatively low magnetic field strength of 1.5 T (6, 7). Most recently, a one‐dimensional (1‐D) 7 Li MRSI study using a surface coil approach at 3 T was reported (8). Although these studies demonstrated the feasibility of the technique and localized signals from lithium were observed, the results were limited.…”

NMR-Active Nuclei for Biological and Biomedical Applications

“…A quantitative 7 Li magnetic resonance spectroscopy study of the normal human brain measured the in vivo T1 of 7 Li as 2.1 ± 0.7 seconds. The mean brain 7 Li concentration was 0.71 ± 0.1 mM, with no significant difference between grey and white matter, and the mean serum concentration was 0.9 ± 0.16 mM [73]. A later quantitative study on bipolar patients stable on long-term lithium treatment demonstrated a biexponential lithium T2 relaxation in the majority of cases with an average short decay time of 5.3 ± 1.4 ms and an average long decay time of 68.2 ± 10.2 ms.…”