Electricity: measuring and testing – Particle precession resonance – Spectrometer components
Patent
1988-05-26
1989-11-07
Levy, Stewart J.
Electricity: measuring and testing
Particle precession resonance
Spectrometer components
324322, G01R 3320
Patent
active
048795160
ABSTRACT:
A magnetic resonance imager includes a quadrature coil assembly (20) for transmitting radio frequency signals into and receiving magnetic resonance signal from an examination region. The quadrature coils assembly includes a first coil (22) and a second coil (24). A shunt path (32, 64, 74, 84, 94, 98, 100, 112, 114, 122) provides a current path by shunting at least a portion of one of the coils. A variable impedance (34, 66, 76, 86, 96, 110, 120) adjusts the amount of current flow through the shunt path and the current flow through the bypassed coil portion. More specifically, adjusting the impedance changes the magnetization vector generated by the coil assembly in a transmit mode and adjusts their relative isolation in a receive mode. The quadrature coils are mounted such that they are offset by about, but not quite, 90.degree.. The variable impedance is adjusted until the offset is brought precisely to 90.degree.. In this manner, the quadrature coils are adjusted electronically after assembly to insure the precision of their isolation.
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Mehdizadeh Mehrdad
Misic George J.
Patrick John L.
Levy Stewart J.
O'Shea Kevin D.
Picker International Inc.
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