NMR local coil with improved decoupling

Details NMR local coil with improved decoupling NMR local coil with improved decoupling

1986-08-15

1988-02-16

Levy, Stewart J.

Electricity: measuring and testing

Particle precession resonance

Spectrometer components

333219, 324311, G01R 3320

Patent

active

047257792

ABSTRACT:
A local coil for use in NMR imaging includes a pair of loop-gap resonators which are geometrically arranged to be intrinsically isolated. The local coil also includes passive decoupling means to completely decouple the local coil during excitation. In a first embodiment, the pair of loop-gap resonators are disposed axially and the passive decoupling means comprises a pair of back-to-back diodes across the loop-gap resonators. In a second embodiment, the pair of loop-gap resonators are disposed in a plane and the passive decoupling means comprises two single turn loops inside each loop-gap resonator with back-to-back diodes across an open segment of each single turn loop. During excitation, the diodes fire thereby lowering the Q and shifting the resonant frequency of the local coil. Using a combination of intrinsic isolation and passive decoupling, the local coil is completely decoupled from the excitation field. During periods of reception, the diodes revert to their nonconducting state and the intrinsic isolation continues to function providing some degree of noise immunity for the local coil.

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