Characterization of the Cerebral Distribution of General Anesthetics in Vivo by Two-dimensional 19F Chemical Shift Imaging

The distribution of two fluorinated anesthetics, halothane and isoflurane, in rabbit brain was mapped during the course of their uptake using 19F NMR chemical shift imaging techniques. Use of a short phase-encoding time and free induction decay acquisition minimized T2-related signal losses in two-dimensional chemical shift imaging. Localization of the brain and exclusion of surrounding tissues was achieved by the use of a surface coil. The spatial distribution of halothane and isoflurane in the brain was nonuniform and both anesthetics were detected predominantly in the cerebral cortex. During the early stages of uptake, anesthetic concentration in the brain was extremely low, but it continued to increase for several hours with sustained anesthetic delivery. Time-dependent variations in anesthetic concentration were observed in different brain regions.