DOUBLE-QUANTUM SURFACE-COIL NMR-STUDIES OF SODIUM AND POTASSIUM IN THE RAT-BRAIN

Double‐quantum filtered and conventional single‐pulse sodium and potassium NMR spectra were obtained from in situ rat brain at 7.0 T, using a surface coil. In contrast to the ca. 14% decrease observed in single‐pulse sodium NMR spectra upon death, increases as large as ca. 800% were observed in double‐quantum filtered sodium spectra. Conversely, a ca. 26% increase was observed in single‐pulse potassium spectra upon death, while double‐quantum filtered potassium spectra decreased below the noise level, for the shortest preparation time used. The decay rate of double‐quantum sodium coherence in the in situ rat brain after death was dependent upon the double‐quantum preparation time: this behavior results from the nonuniformity of the brain, and may be related to physiological com‐partmentalization. The potential application to sodium NMR imaging of cerebral functionality is briefly discussed. © 1991 Academic Press. Inc. Copyright © 1991 Wiley‐Liss, Inc., A Wiley Company