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EP0250050A1 Expired / Lapsed EP ⏱️ 0.0 years remaining

Method of reconstructing a nuclear magnetization distribution from a partial magnetic resonance measurement

Assignee: Koninklijke Philips NV
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Filing: 1987-06-16
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Granted: —
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Expires: 2007-06-16
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Abstract

Abstract Methods are known for reconstructing magnetic resonance images from a magnetic resonance measurement performed on a body, which methods utilize only one half (or slightly more) of the data of the complete resonance measurement for reaching a resolution corresponding to a complete resonance measurement. Such methods utilize an estimation of the phase of the image from data known as sampling values from a central part of a data matrix filled with the sampling values, the partly filled data matrix being supplemented by zeroes prior to the reconstruction of the image. The known methods offer reasonable results, subject to the condition that the phase of the image varies smoothly and changes slowly in the relevant image dimensions. A method is proposed for reducing the residual artefacts, such as blurring, which occurs in the image when the known methods are used for example due to phase errors. In accordance with the proposed method, a number of steps are performed per column in the data matrix so as to produce an ever better estimation for the data not known from sampling. After the reconstruction, the image will have a phase which at least approximates the phase estimated from the central part of the data matrix. In the case of phase errors, substantially no residual artefacts will remain and at the same time the signal-to-noise ratio in the image will be superior to that obtained by means of the known methods.

Inventors

  • 👤 Johannes Josephus Maria Cuppen

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-07 12:56
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/54; G01R33/56; G01R33/561

Claims Analysis

Total Claims: 6
Claim 1
Independent Claim 198 words
A method of reconstructing an at least one-dimensional image of a nuclear magnetization distribution in a body by a complex Fourier transformation of an at least one-dimensional data matrix which is filled with sampling values of resonance signals obtained from a magnetic resonance measurement performed on the body, the data matrix in one dimension at least half being filled with sampling values, a real and an imaginary image component being obtained after the complex Fourier transformation, the reconstruction utilizing a phase which is estimated from data of a central part of the data matrix which is known as sampling values, characterized in that in the case of more than one dimension, the complex Fourier transformation is performed first on the sampling values in the other dimensions, in the one dimension a Fourier transformation step being performed on each column partly filled with sampling values in a number of steps after an estimation for the data not known from sampling, the estimation of the data not known from sampling being adapted in each subsequent step in order to obtain, after reconstruction, an image whose phase at least approximates the phase estimated from the central part of the data matrix.
Claim 2
Independent Claim 198 words
A method of reconstructing an at least one-dimensional image of a nuclear magnetization distribution in a body by a complex Fourier transformation of an at least one-dimensional data matrix which is filled with sampling values of resonance signals obtained from a magnetic resonance measurement performed on the body, the data matrix in one dimension at least half being filled with sampling values, a real and an imaginary image component being obtained after the complex Fourier transformation, the reconstruction utilizing a phase which is estimated from data of a central part of the data matrix which is known as sampling values, characterized in that in the case of more than one dimension, the complex Fourier transformation is performed first on the sampling values in the other dimensions, in the one dimension a Fourier transformation step being performed on each column partly filled with sampling values in a number of steps after an estimation for the data not known from sampling, the estimation of the data not known from sampling being adapted in each subsequent step in order to obtain, after reconstruction, an image whose phase at least approximates the phase estimated from the central part of the data matrix.
Claim 3
Dependent Claim 113 words
A method as claimed in Claim 1, involving an initial estimation for the data not known from sampling, characterized in that in a step after the Fourier transformation step of the column a next estimation is obtained from the data not known from sampling in the column from an image profile thus obtained in the one dimension, said next estimation, after Fourier transformation thereof followed by elimination of the phase, increasing the real image component in the image profile and decreasing the imaginary image component in the image profile, after which in subsequent steps ever smaller imaginary image components and an ever better approximation of the phase of the image profile are obtained.
Claim 4
Dependent Claim 42 words
A method as claimed in Claim 2, characterized in that the next estimation for the data not known from sampling values is realized by performing a Fourier transformation on the conjugated complex image profile of the preceding estimation with double the phase.
Claim 5
Independent Claim 24 words
A method as claimed in any one of the preceding Claims characterized in that each estimation is performed in a fixed number of steps.
Claim 6
Independent Claim 15 words
A device for performing a method as claimed in any one of the preceding Claims.

References Cited (Backward Citations)

WO1985005693A1 Cited
FR2574551A1 Cited
EP0208483A2 Cited
EP0211277A1 Cited

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