ANALYSIS WITH NMR LOCALIZED SPECTROSCOPY OF RAT-BRAIN IN-VIVO AND EX-VIVO

The volume-selected MRS of rat brain was performed on a 200 MHz broad horizontal-bore nuclear magnetic resonance imaging spectrometer. The l ocalized proton spectroscopy of rat brain was acquired using the doubl e spin-echo pulse sequence (PRESS) to select the position and size of the volume. Water signal was suppressed hy CHESS sequence which was co mposed of chemical shift selective rf pulses and dephasing gradients. The parameter TE was taken as 40 ms and 135 ms in the experiment. The localized MRS oi the rat brain with the status of live and death was o btained in various TE values. Results showed that volume-selected prot on MRS of the rat brain in vivo with longer TE consisted mainly of sig nals produced by N-acetylaspartate (NAA), creatine (Crc), choline (Cho ) and rite lactate spectral peak occurred in the MRS oi the rat brain ex vivo. On the other hand, the MRS of the rat brain with shorter TE c ontained glutamine/glutamate and lipid signals besides those signals m entioned previously. Although the information abstracted from the MRS of the rat brain with shorter TE mag-be more than that with longer TE, the spectral resolution of the MRS with shorter TE was slightly worse , in addition, it might indicate that the absolute concentration of NA A was decreased in dead rat brain because the SNR of NAA peak in the M RS ex vivo got lower.