Magnetic resonance spectroscopy as a tool for psychopharmacological studies

Lithium has a natural abundance of 93% and a relatively high MR visibility, 29% relative to hydrogen CH). As therapeutic serum levels are in the range of 1 mEqlL, brain lithium levels may be detected and quantified with relative ease [1]. This was first demonstrated by Renshaw and Wicklund reference lithium brain lithium 50 40 30 20 10 ppm o −10 −20 FIGURE 1 7Li-MRS. Lithium resonances from a 6-cm axial slice through the brain (center) and from an external standard (left). (Data from the McLean Hospital Brain Imaging Center.) in 1988 [2] (Fig. 1); subsequently, a number of research groups have developed methods for measuring brain lithium levels [3,4]. In practice the major problems associated with measuring brain lithium levels are the hardware requirements for detection of the lithium-7 eLi) nucleus and the relatively slow relaxation rates of this weakly quadrupolar, spin 3/2 nucleus [5].