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EP0121312A2
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EP
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High speed NMR imaging system
Assignee: Individual
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Filing: 1984-02-17
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Granted: —
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Expires: 2004-02-17
Abstract
Abstract A cross-sectional image ofthe NMR activity in the body is formed by taking a sequence of projections, each having a differenttransverse gradient structure. Following each excitation the spins in the cross section are driven back to equilibrium. For imaging relaxation times, the sequence of projection signals are processed so as to represent an acquisition at a specific desired time.
Inventors
- 👤 Albert Macovski
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 22:32
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/54; G01R33/56; G01R33/561; G01R33/50
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
90 words
In a method for producing a cross-sectional planar image of an object using nuclear magnetic resonance the steps of: exciting the magnetization of a plane of the object in the presence of a magnetic gradient normal to the plane; receiving rf signals from the nuclear spins in the plane using a first transverse gradient arrangement; processing the received rf signals to produce projection signals; driving the magnetization in the plane back to equilibrium; repeating the sequence using different transverse gradient arrangements; and reconstructing the cross-sectional image using the projection signals.
Claim 2
Dependent Claim
90 words
In a method for producing a cross-sectional planar image of an object using nuclear magnetic resonance the steps of: exciting the magnetization of a plane of the object in the presence of a magnetic gradient normal to the plane; receiving rf signals from the nuclear spins in the plane using a first transverse gradient arrangement; processing the received rf signals to produce projection signals; driving the magnetization in the plane back to equilibrium; repeating the sequence using different transverse gradient arrangements; and reconstructing the cross-sectional image using the projection signals.
Claim 3
Dependent Claim
62 words
2 . The method as described in claim 1 where the step of driving the magnetization back to equilibrium includes the steps of: inverting the nuclear spins in the plane following the decay of the received signal; and exciting the plane with an rf pulse occurring at the peak of the received spin echo signal providing a tipping angle of substantially 90°.
Claim 4
Dependent Claim
48 words
The method as described in claim 1 where the sequence of excitations occur during a relaxation period of the nuclei in the plane and including the step of processing the array of projection signals so that they substantially represent the signals that would occur at a specific time.
Claim 5
Dependent Claim
48 words
4 . The method as described in claim 3 where the step of processing the I signals includes the step of multiplying the projection signals by the ratio of the Integral of the projection signals occurring substantially at the specific time to the integral of the projection signals.
Claim 6
Dependent Claim
57 words
The method as described in claim 3 where the step of processing the signals includes the step of multiplying the exponential portions of the projection signals by the ratio of the integral of the exponential portions of the projection signals occurring substantially at the specific time to the integral of the exponential portions of the projection signals.
Claim 7
Dependent Claim
56 words
6 . The method as described in claim 3 where the sequence of excitations Includes pairs of excitations each having the same transverse gradient arrangement with each excitation occurring substantially equally before and after the specific time and where the step of processing includes the step of adding the projection signals resulting from each excitation pair.
Claim 8
Dependent Claim
40 words
The method as described in claim 6 including the step of multiplying the added projection signals by the ratio of the integral of the projection signals occurring substantially at the specific time to the integral of the added projection signals.
Claim 9
Dependent Claim
52 words
The method as described in claim 6 including the step of multiplying the exponential portions of the added projection signals by the ratio of the integral of the exponential portions of the projection signals occurring substantially at the specific time to the integral of the exponential portions of the added projection signals.
Claim 10
Dependent Claim
78 words
Apparatus for providing an image of the nmr activity in a region comprising: means for providing a sequence of rf excitations each involving a different magnetic gradient to provide an array of received signals; means for processing the received signals to form an array of projection signals; means for driving the magnetization resulting from the rf excitations back to equilibrium between rf excitations; and means for reconstructing the image of the region using the array of projection signals.
Claim 11
Dependent Claim
78 words
Apparatus for providing an image of the nmr activity in a region comprising: means for providing a sequence of rf excitations each involving a different magnetic gradient to provide an array of received signals; means for processing the received signals to form an array of projection signals; means for driving the magnetization resulting from the rf excitations back to equilibrium between rf excitations; and means for reconstructing the image of the region using the array of projection signals.
Claim 12
Dependent Claim
60 words
Apparatus as described in claim 9 wherein the means for driving the magnetization back to equilibrium includes: means for exciting the region with an rf inversion pulse following the decay of the received signal; and means for exciting the region with an rf pulse occurring at the peak of the received spin-echo signal providing a tipping angle of substantially 90°.
Claim 13
Dependent Claim
46 words
Apparatus as described in claim 9 wherein the sequence of rf excitations occur during a relaxation period of the nuclei in the region and including means for processing the array of projection signals so that they substantially represent signals that would occur at a specific time.
Claim 14
Dependent Claim
45 words
. Apparatus as described in claim 11 wherein the means for processing the projection signals includes means for multiplying the projection signals by the ratio of the integral of the projection signals occurring substantially at the specific time to the integral of the projection signals.
Claim 15
Dependent Claim
56 words
Apparatus as described in claim 11 wherein the means for processing the projection signals includes means for multiplying the exponential portions of the projection signals by the ratio of the integral of the exponential portions of the projection signals occurring substantially at the specific time to the integral of the exponential portions of the projection signals.
Claim 16
Dependent Claim
33 words
Apparatus as described in claim 11 wherein the means for processing the projection signals includes means for multiplying the exponential portion of the projection signals by a function of the average relaxation time.
References Cited (Backward Citations)
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