Patent EP0218726A1 successfully refreshed from Google Patents.
EP0218726A1
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Method and apparatus for nuclear magnetic resonance for taking picture of cross section
Assignee: GE Healthcare Japan Corp
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Filing: 1985-07-02
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Granted: —
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Expires: 2005-07-02
Abstract
Abstract A method and apparatus for nuclear magnetic resonance for taking a picture of cross section relying upon the scan sequence of the Fourier method to obtain data without being affected by the static magnetic field that changes with the lapse of time. View data G(k, t) for a sample is measured where the spin phase in the sample is twisted in one direction by a given amount, and other view data G(-k, t) of a sample is measured where the spin phase in the sample is twisted in the opposite direction by the same amount within a period of time in which the intensity of static magnetic field changes neglib- ibly with the lapse of time. From these view data G(k, tl and G(-k,t) are taken data G(k, To) and G(-k,-t o ) at moments to and -to that are symmetrically relative to each other with respect to the origin of time of these view data. As for the data G(-k, -to), a complex conjugate GI-k, -to) is found, and a ratio A = G(k, to) G(-k, -to) of the data G(k, to) to G(-k, -to) is also found. The measured data is corrected by a signal which varies in proportion to an argument arg (A) of the ratio A.
Inventors
- 👤 Eiji Yoshitome
- 👤 Kazuya Hoshino
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 20:22
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/4818; G01R33/482; G01R33/54; G01R33/56; G01R33/565; G01R33/56563
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
208 words
A method of nuclear magnetic resonance imaging employing the Fourier transform imaging, comprising the steps of: measuring the view data G(k,t) for the body which is under diagnosis, under the condition that there is a specific value of twist of spin phase within said body, in a specific direction; measuring the view data G(-k,t) for the body which is under diagnosis, under the condition that the value of twist of the spin phase within said body is equal in amount and of opposite direction to the aforementioned value of twist of spin phase, with the time which elapses between said measurements of G(k,t) and G(-k,t) being sufficiently short that any change in the static magnetic field occurring therein can be ignored; deriving from said view data G(k,t) and G(-k,t) the data G(k,t o ) and G(-k,-to), for the respective time points to and -to which are mutually symmetrically disposed with respect to the time origin of said view data G(k,t) and G(-k,t); deriving the complex conjugate G(-k,-t 0 ) of the data G(-k,-t 0 ); deriving a value A which is the ratio G(k,t 0 )/ G(- k,-t 0 ), and; correcting measured data by a signal which is proportional to the argument arg(A) of the ratio A.
Claim 2
Independent Claim
208 words
A method of nuclear magnetic resonance imaging employing the Fourier transform imaging, comprising the steps of: measuring the view data G(k,t) for the body which is under diagnosis, under the condition that there is a specific value of twist of spin phase within said body, in a specific direction; measuring the view data G(-k,t) for the body which is under diagnosis, under the condition that the value of twist of the spin phase within said body is equal in amount and of opposite direction to the aforementioned value of twist of spin phase, with the time which elapses between said measurements of G(k,t) and G(-k,t) being sufficiently short that any change in the static magnetic field occurring therein can be ignored; deriving from said view data G(k,t) and G(-k,t) the data G(k,t o ) and G(-k,-to), for the respective time points to and -to which are mutually symmetrically disposed with respect to the time origin of said view data G(k,t) and G(-k,t); deriving the complex conjugate G(-k,-t 0 ) of the data G(-k,-t 0 ); deriving a value A which is the ratio G(k,t 0 )/ G(- k,-t 0 ), and; correcting measured data by a signal which is proportional to the argument arg(A) of the ratio A.
Claim 3
Dependent Claim
58 words
A method of nuclear magnetic resonance imaging according to claim 1, in which the proportional constant of said signal employed for correction of measured data is -1/(2γT), where γ is the magnetogyric ratio of spin and T is the time which elapses from the point of termination of selective excitation of spin until the time origin of measurement.
Claim 4
Dependent Claim
63 words
A method of nuclear magnetic resonance imaging according to claim 1, in which said measurement of view data G(k,t) and G(-k,t) is performed by taking a plurality of measurements, each taken under the condition that the amount of twist of spin phase is small, with the times at which said plurality of measurements are made being substantially uniformly dispersed throughout a scan sequence.
Claim 5
Dependent Claim
24 words
A method of nuclear magnetic resonance imaging according to claim 1, in which said measurements of view data G(k,t) and G(-k,t) are performed consecutively.
Claim 6
Dependent Claim
98 words
A method of nuclear magnetic resonance imaging according to claim 1, in which, in said derivation of data G(k,t 0 ) and G(-k,-t 0 ) for the time points to and - t 0 which are mutually symmetrically disposed with respect to the. time origin a plurality of pairs of said data values G(k,t o ) and G(-k,-to) are derived for respectively different values of t 0, with said signal used to correct measured data being made proportional to the average value of the arguments arg(A) which are obtained based on said plurality of pairs of data values.
Claim 7
Dependent Claim
24 words
A method of nuclear magnetic resonance imaging according to claim 1, in which the spin warp imaging is employed with the Fourier transform imaging.
Claim 8
Independent Claim
213 words
An apparatus for nuclear magnetic resonance imaging, comprising: means for measuring the view data G(k,t) for a body which is under diagnosis, under the condition that there is a specific amount of twist of the spin phase within said body in a specific direction, and for measuring the view data G(-k,t) for the body which is under diagnosis, under the condition that the value of twist of the spin phase within said body is equal in amount and of opposite direction to the aforementioned value of twist of spin phase, with the time which elapses between said measurements of G(k,t) and G(-k,t) being made sufficiently short that any change in static magnetic field occurring therein can be ignored; means for deriving from the view data G(k,t) and G(-k,t) the data G(k,t o ) and G(-k,-t 0 ), for the respective time points to and -to which are mutually symmetrically disposed with respect to the time origin of said view data G(k,t) and G(-k,t); means for deriving the complex conjugate G(-k,-t 0 ) of the data G(-k,-to); means for deriving a value A which is the ratio G(k,t 0 )/ G(-k,-t 0 ) , and; means for correcting measured data by a signal which is proportional to the argument arg(A) of the ratio A.
Claim 9
Independent Claim
213 words
An apparatus for nuclear magnetic resonance imaging, comprising: means for measuring the view data G(k,t) for a body which is under diagnosis, under the condition that there is a specific amount of twist of the spin phase within said body in a specific direction, and for measuring the view data G(-k,t) for the body which is under diagnosis, under the condition that the value of twist of the spin phase within said body is equal in amount and of opposite direction to the aforementioned value of twist of spin phase, with the time which elapses between said measurements of G(k,t) and G(-k,t) being made sufficiently short that any change in static magnetic field occurring therein can be ignored; means for deriving from the view data G(k,t) and G(-k,t) the data G(k,t o ) and G(-k,-t 0 ), for the respective time points to and -to which are mutually symmetrically disposed with respect to the time origin of said view data G(k,t) and G(-k,t); means for deriving the complex conjugate G(-k,-t 0 ) of the data G(-k,-to); means for deriving a value A which is the ratio G(k,t 0 )/ G(-k,-t 0 ) , and; means for correcting measured data by a signal which is proportional to the argument arg(A) of the ratio A.
Claim 10
Dependent Claim
58 words
An apparatus for nuclear magnetic resonance imaging according to claim 7, in which the proportional constant of said signal employed for correction of measured data is -1/(2γT), where γ is the magnetogyric ratio of spin and T is the time which elapses from the point of termination of selective excitation of spin until the time origin of measurement.
Claim 11
Dependent Claim
64 words
An apparatus for nuclear magnetic resonance imaging according to claim 7, in which said means for measurement of view data G(k,t) and G(-k,t) acts to perform a plurality of measurements, each taken under the condition that the amount of twist of spin phase is small, with the times at which said plurality of measurements are made being substantially uniformly dispersed throughout a scan sequence.
Claim 12
Dependent Claim
33 words
An apparatus for nuclear magnetic resonance imaging according to claim 7, in which said means for measurement of view data G(k,t) and G(-k,t) acts to perform said measurements of G(k,t) and G(-k,t) consecutively.
Claim 13
Dependent Claim
106 words
An apparatus for nuclear magnetic resonance imaging according to claim 7, in which, in said means for correction of measured data, which derives data G(k,t o ) and G(-k,-t 0 ) for time points t 0 and -to that are mutually symmetrically disposed with respect to the time origin, acts to derive a plurality of pairs of said data values G(k,t o ) and G(-k,-to) for respectively different values of t 0 , and causes said signal used to correct measured data to be made proportional to the average value of the arguments arg(A) which are obtained based on said plurality of pairs of data values.
Claim 14
Dependent Claim
28 words
An apparatus for nuclear magnetic resonance imaging according to claim 7, in which said Fourier transform imaging scan sequence means comprise sequence means for the spin warp imaging.
References Cited (Backward Citations)
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