Inhomogeneity-free heteronuclear iMQC

Abstract

Intermolecular dipolar interactions between proton and carbon spins can be used to indirectly detect carbon spectra with high sensitivity. In this communication, we present a modified sequence that, in addition to the high sensitivity of heteronuclear intermolecular multiple quantum coherence (iMQC) experiments, retains the line narrowing capability characteristic of homonuclear zero quantum coherences. We demonstrate that this sequence can be used to obtain high resolution 13 C spectra in the presence of magnetic field inhomogeneities, both for thermal and hyperpolarized samples, and discuss applications to water-hyperpolarized carbon imaging.

Fast quantification of fatty acid profile of intact fish by intermolecular double‐quantum coherence 1H‐NMR spectroscopy

“…It shows great potential for non‐invasive investigation of lipids, such as in fish nutrition and quality, fat‐related human diseases of clinical diagnostics as well as physiological research. The low sensitivity of the iDQC method may pose an obstacle in some practical applications, so incorporation of signal enhancement techniques may be needed, for example, the use of Hadamard encoding , hyperpolarization , and higher magnetic fields.…”

Correlation distance dependence of the resonance frequency of intermolecular zero quantum coherences and its implication for MR thermometry

“…The situation will be different for a system of mixed heteronuclear spins, in which the effect of microscopic field inhomogeneities on the iZQC frequency, although reduced, cannot be completely removed, as the frequency offset Δω ( r i ) produced by the susceptibility gradients will be different for the different nuclei. However, with an appropriate selection of zero and double quantum coherences, the iMQC signal can be made to evolve at in the indirect dimension , such that the dependence of the frequency on sample microstructure will be eliminated.…”

“…b : Heteronuclear iZQC sequence. c : Modified version of the inhomogeneity‐free iDQC/iZQC sequence proposed in .…”

“…The iMQC signal is generated by exceedingly small long‐range dipolar interactions among spins that reside in different molecules , and sometimes even in different compartments . In the past, these signals have been used for a wide range of imaging and spectroscopy applications, which include contrast enhancement in MRI experiments , and suppression of temporal and spatial inhomogeneities . The removal of macroscopic field inhomogeneities via iMQCs is typically accomplished by the selection of a specific order of coherence, the intermolecular zero‐quantum coherences (iZQCs), even though, in general, with a proper design of the pulse sequence any other coherence can be used for such a purpose .…”

Remote detection of hyperpolarized 129Xe resonances via multiple distant dipolar field interactions with 1H

“…For example, imaging sequences utilizing DDF have been devised to provide new contrast in magnetic resonance imaging applications, 7,8 to reduce linewidths in magnetic resonance spectroscopy experiments in the presence of large magnetic field inhomogeneities, [9][10][11] for functional MRI studies, 12,13 for brown adipose tissue detection, [14][15][16] and to measure temperature in vivo with high accuracy. 17,18 The main feature of DDF-based sequences is that the DDFderived signal comes primarily from pairs of nuclear spins that are separated by a "correlation distance," a user-controllable distance that can be tuned from a few micrometers to several millimeters, allowing sample structures to be probed at a microscopic scale without the loss of sensitivity.…”