Magnetic resonance apparatus

Claim 2

An apparatus according to Claim 1 wherein the gradient coil (44, 80) is mounted on a dielectric substrate (50) disposed between the gradient coil (44, 80) and the radio frequency coil (70, 82).

Claim 3

An apparatus according to Claim 2 wherein the dielectric substrate (50) has a dielectric constant less than 4.0.

Claim 6

An apparatus according to Claim 5 wherein the filter means (64) are mounted intermittently along the gradient coil (44, 80) to connect electrical conductor segments to block the flow of the radio frequency currents thereacross while permitting the flow of lower frequency currents for generating gradient magnetic fields.

Claim 7

An apparatus according to Claim 5 wherein the filter means (60) are connected between ground and intermediate points along the electrical conductors (52), the filter means (60) selectively passing the preselected radio frequency signal to ground while blocking the flow of kHz range currents for generating the gradient magnetic fields.

Claim 10

An apparatus according to Claim 9 further including a radio frequency shield (76, 84) between the insertable gradient coil (44, 80) and the whole body radio frequency coil (32) for preventing radio frequency signals of the preselected radio frequency from the insertable radio frequency coil (70, 82) from reaching the whole body radio frequency and whole body gradient coils (30 and 32).

Claim 13

A magnetic resonance apparatus comprising: an array of annular magnets (10) for generating a substantially uniform, static magnetic field through a central bore (12) thereof; a whole body gradient magnetic field coil assembly (30) mounted around the central bore (12) for selectively generating gradient magnetic fields within the central bore (12); a whole body radio frequency coil assembly (32) mounted around the central bore (12) adjacent the whole body gradient magnetic field coil assembly (30) for selectively generating radio frequency signals in and receiving radio frequency signals from the central bore (12); a radio frequency transmitter (110) which is connectable with the whole body radio frequency coil assembly (32) for supplying radio frequency signals of a selected frequency thereto; and a radio frequency receiver (116) which is connectable with the whole body radio frequency coil assembly (32) for receiving and demodulating radio frequency magnetic resonance signals of substantially the selected radio frequency therefrom; characterised by: a coil assembly (44, 80, 70, 82) insertable into the central bore (12) and including a gradient coil (44, 80) and a radio frequency coil (70, 82) which are mounted in close proximity to each other without an intervening shield coil, the radio frequency transmitter (110) and receiver (116) being selectively connectable with the insertable radio frequency coil (70, 82), the insertable gradient and radio frequency coils (44, 80 and 70, 82) being configured such that the gradient coil (44, 80) has high impedances at the selected radio frequency and such that capacitive coupling between the radio frequency and gradient coils (44, 80 and 70, 82) is minimized.

Claim 14

An apparatus according to Claim 13 wherein a dielectric former (50) having a dielectric constant of less than 4.0 is disposed between, and supports at least one of, the insertable radio frequency and gradient coils (70, 82 and 44, 80).

Claim 15

An apparatus according to Claim 13 wherein the insertable gradient coil (44, 80) includes narrow, relatively widely spaced electrical conductors (52) which are interconnected with filters (60, 64) which inhibit the electrical conductors (52) from supporting currents of said selected radio frequency and support currents in a kHz range for generating the magnetic field gradients.

Claim 16

An apparatus according to Claim 13 further including an RF filter (106) connected with the insertable gradient coil (44, 80) and interconnected between the insertable gradient coil (44, 80) and an electrical cable (108) connecting the insertable gradient coil (44, 80) with a gradient magnetic field control (100) for preventing signals of said selected radio frequency from being transmitted from the cable (108) to the insertable gradient coil (44, 80).

Claim 17

An apparatus according to Claim 13 wherein the insertable gradient coil (44, 80) includes a first pair of coil portions (44A, B or 90A, B) for generating magnetic field gradients along a second axis orthogonal to the first axis and wherein the insertable radio frequency coil (70, 82) is a quadrature detection radio frequency coil which is oriented for quadrature detection along quadrature detection axes which are rotated about 45° relative to the first and second orthogonal axes.

Claim 18

An apparatus according to Claim 13 wherein the insertable radio frequency (70, 82) and gradient (44, 80) coils include a pair of gradient coil portions (44A, B or 80A, B) which are mounted on parallel planes on opposite sides of an examination region and a pair of radio frequency coil portions (70A, B or 82A, B) which are mounted on parallel planes on opposite sides of the examination region and further including a radio frequency shield (76 or 84) mounted around the insertable coil assembly (44, 70, 80, 82) between the insertable coil assembly (44, 70, 80, 82) and the whole body radio frequency and gradient magnetic field coil assemblies (30, 32).