Fast acquisition scheme for achieving high‐resolution MRS with J‐scaling under inhomogeneous fields

Abstract

Intermolecular multiple-quantum coherences (iMQCs) can refocus the phase dispersion caused by magnetic field inhomogeneities while preserving the chemical shift, so they have been applied to achieve high-resolution MR spectroscopy free of line broadening caused by susceptibility gradients. However, previous iMQC high-resolution methods all require two-dimensional spectra sampling of the full range of chemical shifts of solute evolutions in both F(1) and F(2) dimensions, resulting in a prolonged scanning time for data acquisition. In this work, sparse sampling in the t(1) dimension and subsequent fold-over correction are used to speed up the intermolecular zero-quantum coherence spectroscopy by up to 50 times on high-field MR systems. Furthermore, three types of spectra with homo-decoupling, original J-coupling constants, and doubled J-coupling constants respectively are obtained with manipulation of the t(1) period. The water suppression is also improved by the combined use of intermolecular double-quantum filter and excitation sculpting. The feasibilities of this group of new sequences are demonstrated by experiments using an agar gel phantom with an air bubble, in vitro pig brain tissues and an intact postmortem mudskipper.