Electricity: measuring and testing – Particle precession resonance – Determine fluid flow rate
Patent
1995-08-23
1996-10-15
Tokar, Michael
Electricity: measuring and testing
Particle precession resonance
Determine fluid flow rate
324309, 1286533, G01V 300
Patent
active
055657761
ABSTRACT:
An excitation pulse, a first refocusing pulse, and a second refocusing pulse are sequentially applied, a flow encode pulse for producing a phase shift in accordance with the velocity of a fluid is applied before the second refocusing pulse, an echo signal is observed after the application of the second refocusing pulse, and a velocity image is reconstructed on the basis of the echo signal. The application phases of the excitation pulse, the first refocusing pulse, and the second refocusing pulse, and the flip angles of the first and second refocusing pulses, are so adjusted that the intensity of the echo signal from the fluid changes in accordance with the velocity. In a stationary part, the absolute value of a spin echo component and the absolute value of a stimulated echo component are equal, and the phase difference between them is 180.degree.. That is, the signal in the stationary part is essentially 0. In a fluid, the absolute values of the spin echo component and the stimulated echo component are equal, and the phase difference between them approaches 0.degree. with increasing velocity. That is, the signal intensity in the fluid increases as the velocity increases. Accordingly, only an echo signal from the fluid can be observed. The intensity of this echo signal increases with velocity. On the basis of the echo signal, the fluid, rather than the stationary part, is imaged, and a velocity image whose luminance changes in accordance with the velocity is reconstructed.
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Kabushiki Kaisha Toshiba
Tokar Michael
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