Magnetic resonance imaging apparatus including an interference-poor r.f. coil

Claim 1

In a magnetic resonance imaging apparatus including a magnet system for generating a substantially steady magnetic field along a central axis in a measurement space, RF coil apparatus comprising: a connection pad proximate said measurement space for excitation with an RF source at a resonance frequency; a generally cylindrical unitary conductor shield within said measurement space directed axially from a first transverse end plane to a second transverse end plane; a first pair of separate coaxial cable feed portions extending from said connection pad to said first end plane, each said coaxial cable feed portion having a center conductor and an individual outer conductor shield, the center conductors of said feed portions being respectively individually fed at said connection pad; the individual outer conductor shields of said feed portions being connected at said first end plane to said generally cylindrical unitary conductor shield; said center conductor having individual outer conductor shields removed so as to form non-individually shielded portions extending from the first end plane to the second end plane within said unitary conductor shield parallel to the central axis and transversely spaced apart from each other, said center conductors at said second coil end plane respectively comprising the center conductors of a pair of individual coaxial cable lead-out portions, each said individual coaxial cable lead-out portion having an individual outer conductor shield which is connected to said unitary conductor shield, and separate means terminating each of said coaxial cable lead-out portions so as to produce a standing wave transverse electric field varying along the length of each center conductor, the length of each lead-out portion and each said termination means being selected to produce a node in the standing wave electric field on the non-individually shielded portion of each center conductor within said unitary conductor shield.

Claim 8

The apparatus according to any of claims 1-4, further comprising a second pair of separate coaxial cable feed portions extending to said first end plane, having their center conductors extending non-individually shielded, within said unitary conductor shield, parallel to the central axis and transversely spaced apart from each other and from said non-individually shielded portions of the center conductors of said first coaxial cable feed portions, having their own coaxial cable lead-out portions and termination means.