Spin‐Noise‐Detected Two‐Dimensional Nuclear Magnetic Resonance at Triple Sensitivity

Abstract

A major breakthrough in speed and sensitivity of 2 D spin‐noise‐detected NMR is achieved owing to a new acquisition and processing scheme called “double block usage” (DBU) that utilizes each recorded noise block in two independent cross‐correlations. The mixing, evolution, and acquisition periods are repeated head‐to‐tail without any recovery delays and well‐known building blocks of multidimensional NMR (constant‐time evolution and quadrature detection in the indirect dimension as well as pulsed field gradients) provide further enhancement and artifact suppression. Modified timing of the receiver electronics eliminates spurious random excitation. We achieve a threefold sensitivity increase over the original snHMQC (spin‐noise‐detected heteronuclear multiple quantum correlation) experiment (K. Chandra et al., J. Phys. Chem. Lett. 2013, 4, 3853) and demonstrate the feasibility of spin‐noise‐detected long‐range correlation.

Nuclear spin noise tomography in three dimensions with iterative simultaneous algebraic reconstruction technique (SART) processing

“…For completeness, we discuss the concept of indirect detection of the spatial dimension in Fourier imaging with spin noise. Even though spin noise has random phase, one can devise a way to encode spatial information in the indirect dimension similarly to the way used for 2D spin-noise-detected spectroscopy (Chandra et al, 2013;Ginthör et al, 2018). This would require a location-encoding gradient sandwiched between two acquisition blocks and incremented in the usual way to yield the indirect k-space dimension.…”

“…(3) Signals acquired in the absence of rf pulses are devoid of limitations imposed by pulse imperfections and bandwidth. The theoretical and technical aspects of nuclear spin noise detected by Faraday induction have been studied extensively in recent years (Marion and Desvaux, 2008;Nausner et al, 2009;Desvaux et al, 2009;Müller et al, 2013;Chandra et al, 2013;Ferrand et al, 2015;Pöschko et al, 2017;Ginthör et al, 2018). In the research we report here, a major sensitivity and image quality improvement in the case of spin noise imaging (SNI; Müller and Jerschow, 2006) is achieved by exploiting the tuning dependence of the spin noise line shape (Pöschko et al, 2014).…”

“…An intrinsic problem of the inverse radon transform is that it almost always produces artifacts if the projections contain substantial noise contributions or if the imaged distribution function is not smooth (Kabanikhin, 2008). In particular, the latter is a relevant restriction in most practical applications, as hard edges are very common features (e.g., bones in the human body).…”

Nuclear spin noise tomography in three dimensions

“…years (Marion and Desvaux, 2008) (Nausner et al, 2009) (Desvaux et al, 2009) (Müller et al, 2013) (Chandra et al, 2013) (Ferrand et al, 2015) (Pöschko et al, 2017) (Ginthör et al, 2018). In the research we report here, a major sensitivity and image quality improvement in the case of spin noise imaging (SNI) (Müller and Jerschow, 2006) is achieved by exploiting the tuning dependence of the spin noise line shape (Pöschko et al, 2014).…”

“…Even though spin noise has random phase, one can devise a way to encode spatial information in the indirect dimension similar to the way used for 2D spin-noise-detected spectroscopy (Chandra et al, 2013) (Ginthör et al, 2018). This would require a location-encoding gradient sandwiched between two acquisition blocks and incremented in the usual way to yield the indirect k-space dimension.…”