Magnetic resonance imaging system
First Claim
1. A magnetic resonance imaging system in which a magnetic resonance phenomenon is caused in an object to be examined, a magnetic resonance signal which is induced by the magnetic resonance phenomenon is detected, projection data, in which resonance data of specific nucleus is projected on a specific slice of the object to be examined, can be obtained in many directions in accordance with a detection signal, an image reconstruction processing using the projection data is performed, and image data which represents at least one of a spin density of the specific nucleus and a relaxation time constant is obtained, comprising an image reconstruction processing means for performing the image reconstruction processing, said image reconstruction processing means comprising:
- a central processing unit for respectively generating data of a reconstruction starting point of projection data about a first line parallel to a second direction in a reconstruction image matrix in which coordinate axes consist of a first direction corresponding to a direction parallel to a projection angle reference direction and the second direction perpendicular to the first direction, and data of a sampling interval and data of a predetermined correction coefficient value of the projection data along the first and second directions for every projection;
a constant generating circuit for sequentially generating respective data of the sampling interval for the second direction and the correction coefficient value for every projection and for generating the reconstruction starting point data of respective lines which are aligned along the first direction and parallel to the second direction in correspondence to the reconstruction starting point of the first line parallel to the second direction, and the sampling intervals for the first and second directions and the correction coefficient value which are provided from said central processing unit;
a reconstructor in which reconstruction sampling positions of the projection data along a line direction parallel to the second direction corresponding to the reconstruction starting points are obtained by adding the sampling intervals to the respective reconstruction starting points in correspondence with the data of the sampling interval for the second direction and the correction coefficient values and reconstruction starting points of the respective lines parallel to the second direction in the reconstruction image matrix which are supplied from said constant generating circuit, thereby performing back projection on the reconstruction image matrix for the sampling positions;
an image memory for accumulating and holding image data which is back-projected by said reconstructor; and
a timing controlling unit for generating control signals for determining an operation timing and supplying the same to said constant generating circuit, said reconstructor and said image memory.
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Abstract
In an MRI system of the present invention, data of a reconstruction starting point, a sampling interval of projection data for respective lines along a specific line direction in a reconstruction image matrix and a predetermined correction coefficient value of the projection data are transferred to a constant generating circuit. In response to these data, the data of the sampling interval and the correction coefficient value for the specific line direction by every projection are generated, and the reconstruction starting points of the respective lines are sequentially generated. An output from the constant generating circuit is supplied to a reconstructor. In the reconstructor, the sampling interval is added to the reconstruction starting point, thereby obtaining reconstruction sampling positions of the projection data for the line direction corresponding to the reconstruction starting point. Then, the projection data corresponding to the respective sampling positions are back-projected onto a coordinate matrix, thereby performing fast back projection for the corresponding lines. Image data which is back-projected by the reconstructor is cumulatively held in an image memory.
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Citations
7 Claims
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1. A magnetic resonance imaging system in which a magnetic resonance phenomenon is caused in an object to be examined, a magnetic resonance signal which is induced by the magnetic resonance phenomenon is detected, projection data, in which resonance data of specific nucleus is projected on a specific slice of the object to be examined, can be obtained in many directions in accordance with a detection signal, an image reconstruction processing using the projection data is performed, and image data which represents at least one of a spin density of the specific nucleus and a relaxation time constant is obtained, comprising an image reconstruction processing means for performing the image reconstruction processing, said image reconstruction processing means comprising:
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a central processing unit for respectively generating data of a reconstruction starting point of projection data about a first line parallel to a second direction in a reconstruction image matrix in which coordinate axes consist of a first direction corresponding to a direction parallel to a projection angle reference direction and the second direction perpendicular to the first direction, and data of a sampling interval and data of a predetermined correction coefficient value of the projection data along the first and second directions for every projection; a constant generating circuit for sequentially generating respective data of the sampling interval for the second direction and the correction coefficient value for every projection and for generating the reconstruction starting point data of respective lines which are aligned along the first direction and parallel to the second direction in correspondence to the reconstruction starting point of the first line parallel to the second direction, and the sampling intervals for the first and second directions and the correction coefficient value which are provided from said central processing unit; a reconstructor in which reconstruction sampling positions of the projection data along a line direction parallel to the second direction corresponding to the reconstruction starting points are obtained by adding the sampling intervals to the respective reconstruction starting points in correspondence with the data of the sampling interval for the second direction and the correction coefficient values and reconstruction starting points of the respective lines parallel to the second direction in the reconstruction image matrix which are supplied from said constant generating circuit, thereby performing back projection on the reconstruction image matrix for the sampling positions; an image memory for accumulating and holding image data which is back-projected by said reconstructor; and a timing controlling unit for generating control signals for determining an operation timing and supplying the same to said constant generating circuit, said reconstructor and said image memory. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification