Electricity: measuring and testing – Particle precession resonance – Using a nuclear resonance spectrometer system
Patent
1993-07-22
1994-08-30
Arana, Louis
Electricity: measuring and testing
Particle precession resonance
Using a nuclear resonance spectrometer system
324307, G01V 300
Patent
active
053431499
ABSTRACT:
In a magnetic resonance imaging system having an automatic power control function for adjusting the transmission power of an RF pulse so as to set a desired flip angle of a spin, in an automatic power control mode, a plane including only a portion of an object to be examined in an imaging region having a uniform field intensity, e.g., a transaxial plane or a plane slightly inclined from the transaxial plane is excited by a gradient magnetic field Gz in the direction of the body axis of the object as a slice gradient magnetic field regardless of a plane to be imaged. The peak values of MR echo signals are detected while the transmission power of the RF pulse is changed. An RF pulse transmission power at which the maximum peak value appears is detected from these detection values. The transmission power of the RF pulse in imaging, i.e., the output of an RF oscillator having a predetermined frequency, is attenuated on the basis of the relationship between the transmission power and the maximum peak value, thereby adjusting the attenuation amount of an attenuator for supplying a current to an RF coil.
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William H. Perman et al., "A Method for Correctly Setting the rf Flip Angle", Magnetic Resonance In Medicine, 9 (1989) Jan., No. 1, Duluth, Minn, US, pp. 16-24.
Arana Louis
Kabushiki Kaisha Toshiba
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