DocumentCode :
994647
Title :
RF front end for a 4.1 Tesla clinical NMR spectrometer
Author :
Vaughan, Thomas J. ; Haupt, David N. ; Noa, Paul J. ; Vaughn, Michael J. ; Pohost, Gerald M.
Author_Institution :
Center for Nucl. Imaging Res., Alabama Univ., Birmingham, AL, USA
Volume :
42
Issue :
4
fYear :
1995
fDate :
8/1/1995 12:00:00 AM
Firstpage :
1333
Lastpage :
1337
Abstract :
With increased signal-to-noise, spatial, temporal, and spectral resolution, blood oxygenation level contrast, and other benefits of high field NMR, 4T NMR systems enhance the potential for using multinuclear imaging and spectroscopy for medical science and clinical diagnostics. A new NMR spectrometer is needed however. The magnet aside, the key difference between present clinical or animal systems, and 4T+ clinical systems is the RF front end. Including the power amplifier, transmit/receive (T/R) switch, preamplifier, and RF coils, the front end is required to operate at power levels, bandwidths, and circuit lengths unique in the NMR field. New technology has been developed for these components to optimize the performance of the spectrometer. To cover broader spectral bandwidths, and to compensate for chemical shift dispersion error, two 15 kW solid state amplifiers have been developed for implementation on a “home-built” 4.1T clinical system. A stripline transformed, nonmagnetic, tuned GaAsFET preamp has been built for achieving high gain and low noise at the RF coil. A nonmagnetic dual quadrature hybrid-PIN diode T/R switch was developed to isolate the RF power amplifier from the receiver. New high frequency coils have made use of tuned cavities and transmission lines
Keywords :
NMR spectrometers; biological NMR; nuclear electronics; 15 kW; 4.1 T; 4.1 Tesla clinical NMR spectrometer; NMR field; RF coils; RF front end; T/R switch; bandwidths; blood oxygenation level contrast; chemical shift dispersion error; clinical diagnostics; high field NMR; multinuclear imaging; nonmagnetic dual quadrature hybrid-PIN diode T/R switch; power amplifier; preamplifier; signal-to-noise; spatial resolution; spectral bandwidths; spectral resolution; stripline transformed nonmagnetic tuned GaAsFET preamp; temporal resolution; transmit/receive switch; tuned cavities; Bandwidth; Coils; Image resolution; Nuclear magnetic resonance; Power amplifiers; Radio frequency; Radiofrequency amplifiers; Spatial resolution; Spectroscopy; Switches;
fLanguage :
English
Journal_Title :
Nuclear Science, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9499
Type :
jour
DOI :
10.1109/23.467862
Filename :
467862
Link To Document :
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