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ABSTRACT:
Alexander Pines and colleagues at Berkeley Lab have developed a method to improve NMR/MRI resolution either inside of poorly shimmed magnets or outside of portable one-sided magnet systems, which accommodate arbitrarily sized samples. This technique will enable for the first time the collection of multidimensional NMR/ MRI information in cases where on-the-spot medical diagnosis is critical, where samples cannot be moved to or placed inside of a superconducting magnet, or where inexpensive, highly inhomogeneous magnets are being used. Other ex situ systems give relaxation data and sometimes slice-selective images, but not spectra and true 3D images. The Berkeley Lab method combines elements of two previous inventions by the Pines research group, RF field matching (IB-1717) and shim pulse refocusing (IB-2026), to alleviate the exacting hardware requirements of the RF field matching method and reduce the power and other technical requirements of shim pulse refocusing. The original RF field matching technique corrects static magnetic field variations with correlative radio frequency field inhomogeneity created by a series of RF pulses precisely varied in energy, duration, and timing. This method requires a well-defined RF field produced by a coil specifically designed to reproduce the spatial static field dependence or just a monotonic behavior. The original shim pulse method depends on modulation of the RF and gradient pulses to create an effectively “shimmed” field. By combining the two techniques, the Berkeley Lab researchers have developed a less demanding and therefore less expensive ex situ methodology. |
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STATUS:
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FOR MORE INFORMATION: Topgaard,D., Martin, R.W., Sakellariou, D., Meriles, C.A., Pines, A., " 'Shim Pulses' for NMR Spectroscopy anmd Imaging," PNAS 2004, 101, 17576-17581. |
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REFERENCE NUMBER: IB-2185 |
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