Electricity: measuring and testing – Particle precession resonance – Using a nuclear resonance spectrometer system
Patent
1993-04-23
1994-09-13
Tokar, Michael J.
Electricity: measuring and testing
Particle precession resonance
Using a nuclear resonance spectrometer system
G01R 3320
Patent
active
053472187
ABSTRACT:
In a spin-echo magnetic resonance sequence a phase encoding gradient magnetic field (39) is applied after the 180.degree. rephasing pulse (32.sub.1). After detection of the spin-echo signal (33) the position dependent phases are compensated for by applying a further gradient magnetic field (39'), identical in size but opposite in sign. The phase difference (.phi..sub.32,1 -.phi..sub.31,1) between the RF-pulses (31.sub.1,32.sub.1) applied within a sequence is constant over the sequences. With no position dependent effects left at the end of a sequence the next sequence can be started immediately following the earlier one. A repetition time TR substantially shorter than the spin-spin relaxation time T.sub.2 is feasible, thereby developing a steady state of the magnetization. A TR of 50 ms or less can be obtained, as well as strong signals for long T.sub.2 substances and good T.sub.2 contrast. RF spoiling by changing phases of RF-pulses in subsequent sequences can destroy the T.sub.2 signal and provide images with pure T.sub.1 contrast.
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Slobod Jack D.
Tokar Michael J.
U.S. Philips Corporation
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