Magnetic resonance imaging system

Claim 2

A magnetic resonance imaging system comprising: magnetic field applying means (1-4, 7, 8, 11) for applying a static field, gradient field pulses, and an RF field to an object to be examined so as to cause mag­netic resonance in an imaging region of the object; a plurality of signal detecting means (9, 10, 11), including a plurality of surface coils (9a-9e) arranged to surround the region of the object, for detecting mag­netic resonance signals from the object through said surface coils (9a-9e); convolution integration means (13) for performing convolution integration of the magnetic resonance sig­nals respectively detected by said plurality of signal detecting means (9, 10, 11) and an inverse Fourier transform result of a weighting function defined in advance as a spatial position function for each of said plurality of surface coils (9a-9e); synthesizing means (13) for additively synthesizing convolution integration results obtained by said convo­lution integration means (13) and corresponding to said plurality of signal detecting means (9, 10, 11); and imaging means (13) for obtaining an image of the imaging region by performing Fourier transform of data obtained by said synthesizing means (13).

Claim 3

A system according to claim 1, wherein the weighting function is a function proportional to a spatial distribution of an RF field generated when an RF current flows in each of said surface coils (9a-9e).

Claim 4

A system according claim 1, further comprising means (13) for measuring the weighting function prior to imaging.

Claim 5

A system according to claim 1, further compris­ing means (13) for calculating the weighting function by a simulation based on an arrangement of said surface coils (9a-9e).

Claim 6

A system according to claim 1, further compris­ing decoupling means (20a-20j) for performing decoupling said plurality of surface coils (9a-9e).

Claim 7

A system according to claim 1, wherein said plurality of signal detecting means (9, 10, 11) include a plurality of A/D converters (19a-19e) for digitizing the magnetic resonance signals detected through said plurality of surface coils (9a-9e) upon sampling at a predetermined sampling interval, and simultaneously detect the magnetic resonance signals from said plural­ity of surface coils (9a-9e).

Claim 8

A system according to claim 1, wherein said plurality of signal detecting means (9, 10, 11) include a plurality of A/D converters (19a-19e) for digitizing the magnetic resonance signals detected through said plurality of surface coils (9a-9e) upon sampling at a predetermined sampling interval, and repeatedly perform sequential sampling of the magnetic resonance signals from said plurality of surface coils (9a-9e) at the sampling interval within a magnetic resonance signal observation time.

Claim 9

A magnetic resonance imaging system comprising: static field applying means (101, 102) for applying a static field to an object to be examined; gradient field applying means (103, 104) for apply­ing gradient field pulses to the object; a homogeneous coil (109) for transmitting/receiving an RF field, said homogeneous coil (109) being arranged to correspond to a desired imaging region of the object and having homogeneous RF field distribution character­istics within a predetermined region; transmitting means (107) for applying an RF field to the object through said homogeneous coil (109); a plurality of surface coils (110) arranged inside said homogeneous coil (109); signal detecting means (111) for detecting magnetic resonance signals generated in the object through said homogeneous coil (109) and said plurality of surface coils (110); imaging processing means (112, 113) for performing imaging processing including image reconstruction of the magnetic resonance signals detected by said signal detecting means (111) and respectively corresponding to said homogeneous coil (109) and said plurality of sur­face coils (110), and generating image data of a plural­ity of channels respectively corresponding to said homogeneous coil (109) and said plurality of surface coils (110); weighting function determining means (113) for obtaining a weighting function as a pixel position func­tion for each of said plurality of surface coils (110) by using the image data of the plurality of channels corresponding to said homogeneous coil (109) and said plurality of surface coils (110); and synthesizing means (113) for obtaining an image of the desired region by performing a weighting/adding operation of pixel data corresponding to the same spatial positions of those image data from among the image data of the plurality of channels which correspond to said surface coils (110), by using the weighting functions.

Claim 10

A magnetic resonance imaging system comprising: static field applying means (101, 102) for applying a static field to an object to be examined; gradient field applying means (103, 104) for apply­ing gradient field pulses to the object; a homogeneous coil (109) for transmitting/receiving an RF field, said homogeneous coil (109) being arranged to correspond to a desired imaging region of the object and having homogeneous RF field distribution character­istics within a predetermined region; transmitting means (107) for applying an RF field to the object through said homogeneous coil (109); a plurality of surface coils (110) arranged inside said homogeneous coil (109); signal detecting means (111) for detecting magnetic resonance signals generated in the object through said homogeneous coil (109) and said plurality of surface coils (110); imaging processing means (112, 113) for performing imaging processing including image reconstruction of the magnetic resonance signals detected by said signal detecting means (111) and respectively corresponding to said homogeneous coil (109) and said plurality of sur­face coils (110), and generating image data of a plural­ity of channels respectively corresponding to said homogeneous coil (109) and said plurality of surface coils (110); weighting function determining means (113) for obtaining a weighting function as a pixel position func­tion for each of said plurality of surface coils (110) by using the image data of the plurality of channels corresponding to said homogeneous coil (109) and said plurality of surface coils (110); and synthesizing means (113) for obtaining an image of the desired region by performing a weighting/adding operation of pixel data corresponding to the same spatial positions of those image data from among the image data of the plurality of channels which correspond to said surface coils (110), by using the weighting functions.

Claim 11

A system according to claim 8, wherein said weighting function determining means (113) obtains RF field distributions of said plurality of surface coils (110) by using the image of the plurality of channels respectively corresponding to said homogeneous coil (109) and said plurality of surface coils (110), and determines the weighting functions on the basis of the RF field distributions.

Claim 12

A system according to claim 8, further compris­ing decoupling means (20a-20j; 162; 163) for decoupling at least adjacent coils of said plurality of surface coils (110).

Claim 13

A system according to claim 10, wherein said decoupling means includes a figure-8-shaped coil (162) which is arranged to overlap said adjacent coils so as to cancel a magnetic flux coupled.

Claim 14

A system according to claim 10, wherein said decoupling means includes a loop-like coil (163) which is arranged to overlap said adjacent coils so as to cancel a magnetic flux coupled.

Claim 15

A system according to claim 8, further compris­ing decoupling means (20a-20j; 162; 163) for decoupling at least some of said plurality of surface coils (110) and said homogeneous coil (109).

Claim 16

A system according to claim 8, further compris­ing decoupling means (20a-20j; 162; 163) for decoupling at least the adjacent coils of said plurality of surface coils (110) and at least some of said plurality of sur­face coils (110) and said homogeneous coil (109).

Claim 17

A system according to claim 8, wherein at least some of said plurality of surface coils (110) are con­stituted by a differential coil (110a-110f) having a pair of identical coils (141, 142) arranged to be coaxial and parallel to each other, said pair of coils (141, 142) being connected to cause currents to flow in opposite directions.

Claim 18

A system according to claim 15, wherein said weighting function determining means (113) obtains RF field distributions of said plurality of surface coils (110) by using the image of the plurality of channels respectively corresponding to said homogeneous coil (109) and said plurality of surface coils (110), and determines the weighting functions on the basis of the RF field distributions.

Claim 19

A system according to claim 15, further com­prising decoupling means (162; 163) for decoupling at least adjacent coils of said plurality of surface coils (110).

Claim 20

A system according to claim 17, wherein said decoupling means includes a figure-8-shaped (162) coil which is arranged to overlap said adjacent coils so as to cancel a magnetic flux coupled.

Claim 21

A system according to claim 17, wherein said decoupling means includes a loop-like coil (163) which is arranged to overlap said adjacent coils so as to cancel a magnetic flux coupled.

Claim 22

A system according to claim 17, further com­prising decoupling means for decoupling at least some of said plurality of surface coils (110) and said homogene­ous coil (109).

Claim 23

A magnetic resonance imaging system comprising: magnetic field applying means (101, 102, 107, 109) for applying a static field and an RF field to an object to be examined so as to cause magnetic resonance in the object; and signal detecting means (110, 111), including a plu­rality of surface coils. (110) arranged to surround a desired region of the object, for detecting magnetic resonance signals from the object through said surface coils (110), each of said surface coils (110) being con­stituted by a differential coil having a pair of identi­cal coils (141, 142) which are coaxially arranged and are connected to cause currents to flow in opposite directions, wherein said plurality of surface coils (110) are arranged such that linking magnetic fields of RF fields generated by at least adjacent coils of said surface coils (110) amount to 0 in intensity, and decoupling is performed between at least said adjacent coils.

Claim 24

A magnetic resonance imaging system comprising: magnetic field applying means (101, 102, 107, 109) for applying a static field and an RF field to an object to be examined so as to cause magnetic resonance in the object; and signal detecting means (110, 111), including a plu­rality of surface coils. (110) arranged to surround a desired region of the object, for detecting magnetic resonance signals from the object through said surface coils (110), each of said surface coils (110) being con­stituted by a differential coil having a pair of identi­cal coils (141, 142) which are coaxially arranged and are connected to cause currents to flow in opposite directions, wherein said plurality of surface coils (110) are arranged such that linking magnetic fields of RF fields generated by at least adjacent coils of said surface coils (110) amount to 0 in intensity, and decoupling is performed between at least said adjacent coils.