1H Detected 13C Echo Planar Imaging

Abstract

Cyclic J cross polarisation (CYCLCROP) is a sensitive method for the noninvasive monitoring of 13C distributions and fluxes. The PRAWN rotating frame Hartmann-Hahn mixing sequence ameliorates problems associated with sensitivity to Hartmann-Hahn mismatch and reduces RF power deposition. The combination of CYCLCROP with echo planar imaging (EPI) for spatial encoding of the proton detected carbon signal allows efficient use of the available signal to be made, permitting a significant improvement in the temporal resolution of any study. We report here on some initial experiments to demonstrate the feasibility of echo planar proton detected 13C imaging using CYCLCROP based upon the PRAWN module, including the application of the technique to the measurement of transport and accumulation of 13C-labelled sucrose in a castor bean seedling. Two methods that can be used to eliminate the effect of the J-splitting in the EP images are presented. In addition, a fast, image-based B1 field-mapping method which may be used to quantitatively map the low frequency RF field in a dual resonant (13C/1H) probe is presented. The technique utilises the above described imaging method, permitting fully quantitative, 64×64 axial field maps to be generated in about a minute.