Radio-frequency antenna system for examining voluminous bodies by nuclear magnetic resonance and imaging apparatus using such a system.

摘要

The invention relates to an antenna system making it possible to confine a radio-frequency magnetic field inside a lenticular volume of revolution. It consists of several coaxial coils akin to radio-frequency current loops: a central coil 2 and at least one pair of lateral coils 3. The radio-frequency magnetic field produced by the coils 3 is 180 DEG out of phase with the field of the central coil 2 and has an amplitude such that the axial component of the field @1 resulting from their superposition decreases rapidly on moving away from the middle plane of the central coil 2. This confinement effect can be enhanced by appending one or more pairs of lateral coils, each 180 DEG out of phase with the preceding one. The antenna system placed in a homogeneous static magnetic field @0 produced by the electromagnet 1 generates a radio-frequency magnetic field @1, perpendicular to @0 which causes the nuclear magnetic resonance NMR of the nuclei located inside the central coil 2, in its middle plane. The antenna system according to the invention is thus, by virtue of its properties of selective irradiation, well suited to applications in NMR imaging. <IMAGE>