EP0122593A2 — Imaging apparatus and method using nuclear magnet…

Claim 1

Independent Claim 250 words

An imaging apparatus using the nuclear magnetic resonance and provided with means (1, 10) for forming a static magnetic field in a predetermined field of view, means (4x, 4z, 5, 6, 7, 8) for forming a gradient magnetic field in said field of view, means (3, 12, 13) for forming a high-frequency magnetic field in said field of view, signal detecting means (3, 14, 15) for detecting a nuclear magnetic resonance signal from a to-be-inspected body (2) placed in said field of view, and a computer (9) for performing an arithmetic operation for the detected signal to obtain the nuclear magnetic resonance signal intensity distribution in said field of view from measured values of said nuclear magnetic resonance signal intensity distribution at various points on a rectangular coordinate system in the Fourier space, said imaging apparatus comprising: a first memory (17) for storing therein first image data, said first image data being obtained, by calculation, from the output of said signal detecting means, said first image data indicating said nuclear magnetic resonance signal intensity distribution in said to-be-inspected body on the basis of a measuring coordinate system; and a second memory (18) for storing therein data with respect to the magnetic field intensity distribution in said field of view, to correct the coordinate of said first image data stored in said first memory on the basis of said data stored in said second memory, thereby producing second image data, said second image data being displayed on a display device (16).

Claim 2

Dependent Claim 250 words

An imaging apparatus using the nuclear magnetic resonance and provided with means (1, 10) for forming a static magnetic field in a predetermined field of view, means (4x, 4z, 5, 6, 7, 8) for forming a gradient magnetic field in said field of view, means (3, 12, 13) for forming a high-frequency magnetic field in said field of view, signal detecting means (3, 14, 15) for detecting a nuclear magnetic resonance signal from a to-be-inspected body (2) placed in said field of view, and a computer (9) for performing an arithmetic operation for the detected signal to obtain the nuclear magnetic resonance signal intensity distribution in said field of view from measured values of said nuclear magnetic resonance signal intensity distribution at various points on a rectangular coordinate system in the Fourier space, said imaging apparatus comprising: a first memory (17) for storing therein first image data, said first image data being obtained, by calculation, from the output of said signal detecting means, said first image data indicating said nuclear magnetic resonance signal intensity distribution in said to-be-inspected body on the basis of a measuring coordinate system; and a second memory (18) for storing therein data with respect to the magnetic field intensity distribution in said field of view, to correct the coordinate of said first image data stored in said first memory on the basis of said data stored in said second memory, thereby producing second image data, said second image data being displayed on a display device (16).

Claim 3

Dependent Claim 38 words

An imaging apparatus using the nuclear magnetic resonance according to Claim 1, wherein said second memory stores therein data indicating the spatial distribution of the deviation of the intensity of said static magnetic field from a predetermined value.

Claim 4

Dependent Claim 60 words

An imaging apparatus using the nuclear magnetic resonance according to Claim 1, wherein said second memory stores therein data indicating the spatial distribution of the deviation of the intensity of said static magnetic field from a predetermined value and data indicating the spatial distribution of the deviation of the intensity of said gradient magnetic field from a predetermined, linearly-varying intensity.

Claim 5

Dependent Claim 65 words

An imaging apparatus using the nuclear magnetic resonance according to Claim 1, wherein said second memory stores therein data previously calculated from measured values with respect to the intensity distribution of said static magnetic field and/or the intensity distribution of said gradient magnetic field for converting said first image data C'(I', J') into said second image data C(I, J) through the transformation of coordinate system.

Claim 6

Dependent Claim 100 words

An imaging apparatus using the nuclear magnetic resonance according to Claim 4, wherein coordinates ç; and n of said first image data corresponding to coordinates I and J on a to-be-displayed image (where I = 0, 1, ..., N-l; J = 0 , 1, ..., N-1) are divided into discrete coordinate components i and j and error components Δ 1 and Δ 2 as indicated by equations Δ 1 ξ= - i and Δ 2 = n-j, and said second memory stores therein said discrete coordinate components i and j and said error components Δ 1 and Δ 2 .

Claim 7

Dependent Claim 77 words

An imaging apparatus using the nuclear magnetic resonance according to Claim 5, wherein said coordinates and n are corrected by said components i, j, Δ 1 , and Δ 2 in such a manner that said second image data is obtained by interpolation from said first image data at four positions having coordinates i and j, coordinates i and j + 1, coordinates i + 1 and j, and coordinates i + 1 and j + 1.

Claim 8

Dependent Claim 93 words

An imaging apparatus using the nuclear magnetic resonance according to Claim 5, wherein said coordinates and n are calculated substantially from the following equations: where G x indicates an intensity increment of a gradient magnetic field having an intensity gradient in an x-direction per one picture element, G y an intensity increment of a gradient magnetic field having an intensity gradient in a y-direction per one picture element, and E(I, J) the deviation of the intensity of said static magnetic field from a predetermined value at a position having coordinates I and J.

Claim 9

Dependent Claim 161 words

An imaging apparatus using the nuclear magnetic resonance according to Claim 5, wherein said coordinates S and n are calculated substantially from the following equations: where G indicates an intensity increment of a gradient magnetic field having an intensity gradient in an x-direction per one picture element, Gyan intensity increment of a gradient magnetic field having an intensity gradient in a y-direction per one picture element, E(I, J) the deviation of the intensity of said static magnetic field from a predetermined value at a position having coordinates I and J, h 1 (I, J) the deviation of the intensity of said gradient magnetic field having an intensity gradient in the x-direction from a predetermined, linearly-varying intensity at said position having the coordinates I and J, and h 2 (I, J) the deviation of the intensity of said gradient magnetic field having an intensity gradient in the y-direction from a predetermined, linearly-varying intensity at said position having the coordinates I and J.

Claim 10

Dependent Claim 179 words

An imaging apparatus using the nuclear magnetic resonance according to Claim 5, wherein a 180° high-frequency pulse is applied to said to-be-inspected body to detect said nuclear magnetic resonance signal, and said coordinates ξ and n are calculated from the following equations: where x is taken in the direction of the gradient of a gradient magnetic field applied for measuring a nuclear magnetic resonance signal, G indicates an intensity increment of a gradient magnetic field having an intensity gradient in an x-direction per one picture element, E(I, J} the deviation of the intensity of said static magnetic field from a predetermined value at a position having coordinates I and J, hl(I, J) the deviation of the intensity of said gradient magnetic field having an intensity gradient in the x-direction from a predetermined, linearly-varying intensity at said position having the coordinates I and J, and h 2 (I, J) the deviation of the intensity of a gradient magnetic field having an intensity gradient in a y-direction from a predetermined, linearly-varying intensity at said position having the coordinates I and J.

Claim 11

Dependent Claim 33 words

An imaging apparatus using the nuclear magnetic resonance according to Claim 1, wherein said second image data is an image signal whose intensity has been corrected by data stored in said first memory.

Claim 12

Dependent Claim 97 words

An imaging apparatus using the nuclear magnetic resonance according to Claim 4, wherein a 180° high-frequency pulse is applied to said to-be-inspected body to detect said nuclear magnetic resonance signal, and wherein one coordinate of coordinates and n of said first image data corresponding to coordinates I and J on a to-be-displayed image is divided into a discrete coordinate component i and an error component A 1 as indicated by an equation Δ 1 = ξ - i, and said second memory stores therein said coordinate component i and said error compo- nen t Δ 1 .

Claim 13

Dependent Claim 57 words

An imaging apparatus using the nuclear magnetic resonance according to Claim 11, wherein said coordinate is corrected by said components i and Δ 1 in such a manner that said second image data is obtained by interpolation from said first image data at two positions having coordinates i and J and coordinates i + 1 and J.

Claim 14

Dependent Claim 69 words

An imaging apparatus .using the nuclear magnetic resonance according to Claim 11, wherein said coordinate is calculated from the following equation: wherein G x indicates an intensity increment of a gradient magnetic field having an intensity gradient in an x-direction per one picture element, and E(I, J) the deviation of the intensity of said static magnetic field from a predetermined value at a position having coordinates I and J.

Claim 15

Dependent Claim 81 words

An imaging method comprising the steps of: (a) measuring values of a nuclear magnetic resonance signal intensity distribution in a field of view at various points on a rectangular coordinate system in the Fourier space, (b) correcting values of coordinates in said measured values in a form of an image data with a data of a magnetic distribution measured in said field of view, and (c) displaying said corrected values in said form of said image data in a display (16).

Claim 16

Dependent Claim 81 words

An imaging method comprising the steps of: (a) measuring values of a nuclear magnetic resonance signal intensity distribution in a field of view at various points on a rectangular coordinate system in the Fourier space, (b) correcting values of coordinates in said measured values in a form of an image data with a data of a magnetic distribution measured in said field of view, and (c) displaying said corrected values in said form of said image data in a display (16).

Imaging apparatus and method using nuclear magnetic resonance

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