Antenna device and magnetic resonance imaging device

摘要

Manufacture cost and maintenance cost of RF coils of MRI devices are reduced without any limitation concerning size of the coils. By constituting an antenna device for magnetic resonance imaging devices with a cylindrical outer conductor, a looped ribbon-shaped conductor disposed inside the cylindrical outer conductor along the cylindrical surface, and a feed point for transmission and/or reception between the cylindrical conductor and the ribbon-shaped conductor, and disposing the ribbon-shaped conductor so that length thereof can be readily adjusted, there is provided an antenna device for magnetic resonance imaging devices that generates a magnetic field component perpendicular to the central axis of the cylinder at a desired resonance frequency and shows sensitivity without using capacitors and without being imposed any limitation concerning size in the diametral direction of the cylinder.

主权项

1. An RF antenna device of an MRI apparatus used for transmission and/or reception of a signal, comprising:
a cylindrical conductor having a cylindrical shape; a ribbon-shaped conductor having a length longer than the circumference of the cylindrical conductor; and a cable connected to the cylindrical conductor and the ribbon-shaped conductor, which transmits and receives signals to and from the RF antenna device, wherein the ribbon-shaped conductor is disposed on a cylindrical surface inside of the cylindrical conductor in the form of a loop so as to generate a magnetic field having a component perpendicular to a central axis of the cylindrical conductor in the inside of the cylindrical conductor, the ribbon-shaped conductor comprises: a plurality of first portions having a component parallel to the central axis direction of the cylindrical conductor, and a plurality of second portions having a component in the circumferential direction of the cylindrical conductor connecting the first portions, wherein the first portions are disposed so that a component along the circumferential direction of the cylindrical conductor of one first portion does not overlap with a component along the circumferential direction of the cylindrical conductor of an adjacent first portion, and where a number of the first portions of the ribbon-shaped conductor is represented as 2N (where N is equal to a wavenumber of an electromagnetic wave to be transmitted or received), a length of the ribbon-shaped conductor is represented as L, and a specific propagation velocity ratio of the whole propagation line of the ribbon-shaped conductor with the cylindrical conductor as a ground plane, with respect to the velocity of light in a vacuum, is represented as A, a value obtained by dividing the length L by the specific propagation velocity ratio A is substantially equal to (N−1) or (N+1) times the wavelength of an electromagnetic wave in a vacuum that resonates with the antenna device.