PURPOSE: Overhauser-enhanced MRI is a promising technique for imaging the distribution and dynamics of free radicals. A key challenge for Overhauser-enhanced MRI is attaining high spatial and temporal resolution while simultaneously limiting resonator and sample heating due to the long, high power radio-frequency pulses needed to saturate the electron resonance. METHODS: The approach presented here embeds EPR pulses within a balanced steady state free precession sequence. Unlike other Overhauser-enhanced MRI methods, no separate Overhauser prepolarization step is required. This steady-state approach also eliminates the problem of time-varying Overhauser-enhanced signal and provides constant polarization in the sample during the acquisition. A further increase in temporal resolution was achieved by incorporating undersampled k-space strategies and compressed sensing reconstruction. RESULTS: We demonstrate 1 x 2 x 3.5 mm3 resolution at 6.5 mT across a 54 x 54 x 110 mm3 sample in 33 s while sampling 30% of k-space. CONCLUSION: The work presented here overcomes the main limitations of Overhauser enhanced MRI as previously described in the literature, drastically improving speed and resolution, and enabling new opportunities for the measurement of free radicals in living organisms, and for the study of dynamic processes such as metabolism and flow. Magn Reson Med, 2013. (c) 2013 Wiley Periodicals, Inc.
[NMR paper] High-resolution paramagnetically enhanced solid-state NMR spectroscopy of membrane proteins at fast magic angle spinning.
High-resolution paramagnetically enhanced solid-state NMR spectroscopy of membrane proteins at fast magic angle spinning.
Related Articles High-resolution paramagnetically enhanced solid-state NMR spectroscopy of membrane proteins at fast magic angle spinning.
J Biomol NMR. 2013 Dec 13;
Authors: Ward ME, Wang S, Krishnamurthy S, Hutchins H, Fey M, Brown LS, Ladizhansky V
Abstract
Magic angle spinning nuclear magnetic resonance (MAS NMR) is well suited for the study of membrane proteins in membrane mimetic and native membrane...
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12-18-2013 04:00 PM
The Nuclear Overhauser Effect from a Quantitative Perspective
The Nuclear Overhauser Effect from a Quantitative Perspective
Publication date: Available online 22 November 2013
Source:Progress in Nuclear Magnetic Resonance Spectroscopy</br>
Author(s): Beat Vögeli</br>
The nuclear Overhauser enhancement or effect (NOE) is the most important measure in liquid-state NMR with macromolecules. Thus, the NOE is the subject of numerous reviews and books. Here, the NOE is revisited in light of our recently introduced measurements of exact nuclear Overhauser enhancements (eNOEs), which enabled the determination of multiple-state 3D...
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11-22-2013 03:09 PM
Overhauser dynamic nuclear polarization-enhanced NMR relaxometry
From The DNP-NMR Blog:
Overhauser dynamic nuclear polarization-enhanced NMR relaxometry
Franck, J.M., R. Kausik, and S. Han, Overhauser Dynamic Nuclear Polarization-Enhanced NMR Relaxometry. Microporous Mesoporous Mater, 2013. 178(0): p. 113-118.
http://www.ncbi.nlm.nih.gov/pubmed/23837010
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11-21-2013 01:14 AM
[NMR paper] Sampling scheme and compressed sensing applied to solid-state NMR spectroscopy.
Sampling scheme and compressed sensing applied to solid-state NMR spectroscopy.
Related Articles Sampling scheme and compressed sensing applied to solid-state NMR spectroscopy.
J Magn Reson. 2013 Oct 1;237C:40-48
Authors: Lin EC, Opella SJ
Abstract
We describe the incorporation of non-uniform sampling (NUS) compressed sensing (CS) into oriented sample (OS) solid-state NMR for stationary aligned samples and magic angle spinning (MAS) Solid-state NMR for unoriented 'powder' samples. Both simulated and experimental results indicate that...
[NMR paper] A comparison of convex and non-convex compressed sensing applied to multidimensional NMR.
A comparison of convex and non-convex compressed sensing applied to multidimensional NMR.
http://www.bionmr.com//www.ncbi.nlm.nih.gov/corehtml/query/egifs/http:--linkinghub.elsevier.com-ihub-images-PubMedLink.gif Related Articles A comparison of convex and non-convex compressed sensing applied to multidimensional NMR.
J Magn Reson. 2012 Oct;223:1-10
Authors: Kazimierczuk K, Orekhov VY
Abstract
The resolution of multidimensional NMR spectra can be severely limited when regular sampling based on the Nyquist-Shannon theorem is used. The...
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02-23-2013 01:51 PM
Compressed sensing reconstruction of undersampled 3D NOESY spectra: application to large membrane proteins
Compressed sensing reconstruction of undersampled 3D NOESY spectra: application to large membrane proteins
Abstract Central to structural studies of biomolecules are multidimensional experiments. These are lengthy to record due to the requirement to sample the full Nyquist grid. Time savings can be achieved through undersampling the indirectly-detected dimensions combined with non-Fourier Transform (FT) processing, provided the experimental signal-to-noise ratio is sufficient. Alternatively, resolution and signal-to-noise can be improved within a given experiment time. However, non-FT...
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07-30-2012 07:42 AM
Compressed sensing and the reconstruction of ultrafast 2D NMR data: Principles and biomolecular applications.
Compressed sensing and the reconstruction of ultrafast 2D NMR data: Principles and biomolecular applications.
Compressed sensing and the reconstruction of ultrafast 2D NMR data: Principles and biomolecular applications.
J Magn Reson. 2011 Apr;209(2):352-8
Authors: Shrot Y, Frydman L
A topic of active investigation in 2D NMR relates to the minimum number of scans required for acquiring this kind of spectra, particularly when these are dictated by sampling rather than by sensitivity considerations. Reductions in this minimum number of scans have...
High speed 3D overhauser-enhanced MRI using combined b-SSFP and compressed sensing
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