Clean multiple echo magnetic resonance imaging using asymmetric

Details Clean multiple echo magnetic resonance imaging using asymmetric Clean multiple echo magnetic resonance imaging using asymmetric

1986-03-03

1987-10-27

Levy, Stewart J.

Electricity: measuring and testing

Particle precession resonance

Using a nuclear resonance spectrometer system

324307, G01R 3320

Patent

active

047032685

ABSTRACT:
A multi-pulse radio frequency signal sequence includes a 90.degree. excitation pulse (50) and at least a first 180.degree. refocusing pulse (52) and a second 180.degree. refocusing pulse (54). The excitation pulse and first refocusing pulse are separated by a duration A and the first and second refocusing pulses are separated by A+B. A free induction decay (60) follows the excitation pulse, a first spin echo (62) occurs a duration A after the first refocusing pulse and a second spin echo (64) occurs the duration B after the second refocusing pulse. A first read gradient (90) is applied between the excitation and first refocusing pulses; a second read gradient (92) is applied between the first refocusing pulse and the first spin echo; a third read gradient (94) is applied between the first spin echo and the second refocusing pulse; and a fourth read gradient (96) is applied between the second refocusing pulse and the second spin echo. Because the 90.degree. and 180.degree. pulses are imperfect, parasitic echoes occur at durations 3A+B, 3A+2B, and 4A+2B after the 90.degree. excitation pulse. To avoid contamination of the spin echo data by the parasitic echoes, the durations A and B are selected such that the parasitic echoes are each displaced from the spin echoes. To shift the parasitic echoes into times which are non-coincident with the spin echoes, the amplitudes of the read gradients are similarly varied between the spin echoes to shift the parasitic echoes relative to the spin echoes.

REFERENCES:
patent: 4297637 (1981-10-01), Crooks et al.
"Spin Echoes" E. L. Hahn, Physical Review, vol. 80, No. 4, Nov. 15, 1950, pp. 580-594.
"Effects of Diffusion on Free Precession in Nuclear Magnetic Resonance Experiments" H. Y. Carr and E. M. Purcell; Physical Review, vol. 94, No. 3, May 1, 1954, pp. 630-638.
"Effects of Diffusion in Nuclear Magnetic Resonance Spin-Echo Experiments", D. E. Woessner Journal of Chemical Physics, vol. 34, No. 6, Jun. 1961, pp. 2057-2061.
"Diffusion and Field Gradient Effects in NMR Fourier Spectroscopy", R. Kaiser, E. Bartholdi, and R. R. Ernst, Journal of Chemical Physics, vol. 60, No. 8, Apr. 1974, pp. 2966-2979.

Affiliated with

Also associated with

Rating

Clean multiple echo magnetic resonance imaging using asymmetric does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Clean multiple echo magnetic resonance imaging using asymmetric , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Clean multiple echo magnetic resonance imaging using asymmetric will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1274130