NMR in vivo multinuclear imaging at 7T

Since the installation of 7T MRI system (NIRS/KOBELCO/Bruker) in October 2004, we have been working on the in vivo multinuclear imaging and MRS. The magnet was developed by NIRS and JASTEC (KOBELCO), 400mm bore, self shielded, and zero boil off freezing system for liquid helium. This report is on the multinuclear applications to the pharmacodynamical study of fluorine containing drug 5-FU with 19F, and 17O imaging towards CMRO2 in mice. In order to obtain images from low concentration or low sensitivity nuclear spins, fast sequences are compared for 19F at 282 MHz, and for 17O at 40MHz. Fast spin echo was better than true-FISP for 19F in giving stable image intensity for all the metabolites in various organs. FSE is also capable of giving the full time course of drug dynamics by simultaneous multi-spectral line selection: the distribution of effective anabolites sepecially at the tumor, the formation and excretion of catabolotes from the liver as well as the fate of administrated drug. The method is benefited by the wide chemical shift separation and high sensitivity of high field MR. For 17O, true-FISP was the best among FISP, FSE and Flash. Unlike the case of 19F, the smaller effect of magnetic susceptibility at the resonance frequency of 40MHz enabled us to use FISP for whole body MRI of 17O.The 6th Japan-France Workshop on Radiobiology and Isotopic imagin