JPH0318350A - Magnetic resonance imaging device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic resonance imaging device (hereinafter referred to as MR device).

[Conventional technology]

For example, in MRI, which can obtain tomographic images of the human body, in order to obtain the necessary tomographic images, a tomographic image is first taken, and from this tomographic image, positional information of the tomographic image to be obtained next is calculated. It is obtained based on the location information.

That is, by setting an arbitrary line that crosses a tomographic image taken on a CRT display using an external input device, it is possible to obtain a new tomographic image in a plane that includes that line and is orthogonal to the tomographic image. It has become.

[Problem to be solved by the invention]

However, in the tomographic image obtained in this way (on a CRT display), there are cases where it is desired to position the edge part of the tomographic image in the center of the display. In this case, the front tomographic image is means for shifting the screen on the display surface.

However, this operation is troublesome, and is mainly performed at the stage of setting a desired tomogram in the base tomogram before obtaining a new tomogram (the stage of setting a line that determines the tomographic part). The part to be observed may be obvious.

Therefore, the present invention has been made in view of the above circumstances, and it is an object of the present invention to obtain a new tomographic image based on a certain tomographic image in a plane perpendicular to the tomographic image by a simple operation. It is an object of the present invention to provide a magnetic resonance imaging device that can immediately display the part of a tomographic image that is desired to be observed at the center of the display.

[Means to solve the problem]

In order to achieve such problems, the present invention basically provides a magnetic resonance imaging apparatus equipped with a display for displaying tomographic images, in which each line or virtual line that crosses the tomographic image is displayed on the display surface. a first means for inputting coordinate information of both end points; a second means for inputting coordinate information of one point on the line; and a plane including the line from the output of the first means and perpendicular to the tomographic image plane. and a fourth means for positioning the one point on the tomographic image plane obtained by the third means from the output of the second means at the center point of the display. It is something.

[Effect]

With this configuration, when setting the tomographic plane to be obtained, the point to be positioned at the center of the tomographic plane, that is, the center of the display, can be set, making the operation extremely simple. -3=4- Therefore, it becomes possible to obtain a new tomographic image in which the part to be mainly observed is positioned at the center of the display.

〔Example〕

An embodiment of the MHI according to the present invention will be described below with reference to the drawings.

FIG. 2 shows an overall configuration diagram of MRI according to the present invention. In the figure, a human body or the like serving as a sample is placed in a uniform magnetic field Ho within a static magnetic field coil 101.

X-axis gradient magnetic field coil 102, Y-axis gradient magnetic field coil 103
, and the Z-axis gradient magnetic field coil 104 are designed to generate mutually orthogonal gradient magnetic fields within the magnetic field Ho, and are used for so-called selective excitation of slices, phase dispersion, and focusing of nuclear spins in the sample. It is now possible to Each gradient magnetic field coil 102, 103, 104
The magnetic strength is determined by controlling the electric power supplied from the gradient magnetic field power supply 105 by the gradient magnetic field control device 106. High frequency magnetic field coil 10
7 is for exciting nuclear spins in the sample, and the high-frequency magnetic field pulse irradiated from here is generated when the output from the high-frequency pulse generator 111 is supplied via the amplifier 109. There is. The shape of the radio-frequency magnetic field pulse determines the shape of the slice, and the amplitude determines the nutation angle of the spins. When the nuclear spins excited by the high-frequency magnetic field pulse are performing free induction decay motion, the signal detection probe 1
A nuclear magnetic resonance signal is induced at 08.

After passing through an amplifier 110, this induced signal is orthogonally detected by a quadrature detector 112 using a signal generated by a high frequency pulse generator 111 as a reference wave. The detected signal is A/D converted by an A/D converter 114 and then taken into a central processing unit 115. Each of the gradient magnetic field coils 102, 103, 104
gradient magnetic field, application timing of the high frequency magnetic field etc. of the high frequency magnetic field irradiation coil 107, magnetic field strength, the A/D converter 11
4 is controlled by the sequencer 1{3-5-, and this sequencer 113 is controlled by the central processing unit 115. Further, the central processing unit 115 includes a keyboard 117,
Output from the trackball 118 is input, and output is also output to the display 116. The display 116 is adapted to be used to display images and other information.

The keyboard 117 transmits various information to the central processing unit 115.
It is designed to be used as an input. The trackball 118 is used to move marks displayed on the display 116.

The MRI having such a basic configuration is capable of performing the following operations. As shown in FIGS. 3 and 4, the tomographic image 1 taken in advance is displayed on the display 116 (step 1), and the mark 3 representing the tomographic plane to be newly taken is specified using the trackball 118 (step 2) trackball 118 again
The mark 4 representing the center of the field of view is designated by (step 3). At this time, the mark 4 can be moved over the previously designated mark 3. Next, when the field of view size is input using the keyboard 117 (step 4), the newly imaged tomographic plane 2 is perpendicular to the tomographic plane 1, has a visual field center 8 that coincides with the mark 4, and also has the input field of view size. It becomes a fault plane with a

Such operations are performed by the central processing unit 115, and the means incorporated in this central processing unit fill5 are as shown in the drawing. Note that in this figure, the display 116 and trackball 118 are shown overlappingly with those shown in FIG. 2 above. In the figure, on the tomographic image obtained on the display 1l6,
Furthermore, specify the tomographic plane (corresponding to code 3 in Figure 4) to be obtained, and the coordinate information of points a and b on this tomographic plane is
It is adapted to be taken out by means 51. The output from the first means 51 is input to the second means 52, where the coordinate information of the points a and b is converted into a virtual coordinate system within the magnet, and the converted coordinate information a ',b' are obtained.

Next, based on the coordinate information a', b', the third means 53 calculates a matrix M to be converted into the cross section B to be photographed next. Further, a fourth means 54 determines the field of view L in cross section B from the distance of the coordinate information a', b'. Furthermore, this field of view L is changed by the fifth means 5' so that the output from the eighth means, which will be described later, is positioned at the center.Then, the fifth means 55 changes the field of view L and its corresponding signal The detection band ωf is determined by calculation.

On the other hand, information regarding the coordinates of the origin ○ of the display 116 is retrieved by a sixth means 56,
This information is converted into a virtual coordinate system within the magnetic field by the seventh means 57, and this conversion information is designated as O'. Next, in the eighth means, this information ○' is coordinate-transformed by the matrix M obtained by the third means 53, and this information is made into ○".Furthermore, in the ninth means, the origin is set to O. The reference frequency ω1 at the time of signal measurement is calculated to set the reference frequency ω1 to ″.

Further, by operating the trackball 118, the point P is moved on the a-b line, and at this time, information regarding the coordinates of the point P is obtained from the trackball 118 by the first O means 60. It looks like this. Next, the eleventh means 61 converts the coordinates of the point P into a virtual coordinate system within the magnetic field, and converts the converted coordinates into a virtual coordinate system within the magnetic field.
’. Further, in the twelfth means 62, the transformed coordinate P' is coordinate-transformed using the matrix M obtained by the third means 53, and this information is set as P'. Then, in the third means 63, the output vector ○"P' from the eighth means 58 is obtained, and from this, the deviation Δω of the reference frequency is calculated. This calculated value Δω is calculated by the fourteenth means 58. 64, and together with the output from the ninth means, a reference frequency ω=ω1+Δω for setting the origin at P' is obtained.

9- Thus, the signal corresponding to ωf from the fifth means 55,
and a signal corresponding to ω from the fourteenth means 64 to
A cross-sectional image perpendicular to the b line is set on the ab line at a point P
It becomes possible to display an image while positioning it at the center of the display earthwork 6. That is, as is well known, a sampling signal is extracted from the MNR signal, and since the interval between the sampling signals is proportional to the visual field, the visual field can be set to any desired value using the signal corresponding to the ωf. . Furthermore, since the period of the NMR signal is proportional to the center shift of the image, the center of the image can be arbitrarily set using the signal corresponding to ω.

FIG. 5 is an explanatory diagram showing another embodiment according to the present invention. In the figure, a mark 5 representing a tomographic plane to be newly imaged is specified using an arbitrary input device for a tomographic image 1 on a CRT that has been previously imaged. This mark 5 may be a solid line or a broken line, and the length of the line represents the size of the field of view. The newly photographed tomographic plane 2 is orthogonal to the tomographic image 1, has a visual field center 8 at the center of the mark 5, and has a visual field size equal to the length of the mark 5. .

The configuration for doing this is such that by specifying the mark 5, a, b, and P shown in FIG. 1 are automatically set, and their information can be retrieved. Signal processing is performed in a configuration similar to that shown in FIG.

Furthermore, FIG. 6 is an explanatory diagram for showing another embodiment. For the tomographic image (2) that has been photographed in advance, a mark 6 representing the edge of the field of view of the tomographic plane to be newly photographed is specified using an arbitrary input device. Next, the mark 7 representing the other end of the visual field is designated using the same input device. At this time, marks 6 and 7 do not necessarily have to be on the same tomographic plane; in any case,
It is assumed that the length between mark 6 and mark 7 represents the size of the field of view of a new tomographic plane. A newly photographed tomographic plane 2 is perpendicular to the tomographic plane 1 and has a visual field center 8 at the center of the marks 6 and 11-12-7.

In this case, if marks 6 and 7 are on different tomographic planes, the center of the field of view is when mark 6 is projected onto the tomographic plane where mark 7 exists, or when mark 7 is projected onto the tomographic plane where mark 6 exists. It is possible to select the length between the two points, or the center between the marks 6 and 7.

In this case as well, by specifying mark 6 and mark 7, a, b and P are automatically set and their information can be obtained, as in FIG.

Furthermore, another embodiment of the present invention will be described with reference to FIG.

A mark 5 representing a tomographic plane to be newly photographed is specified using an arbitrary input device for a tomographic image 1 on a CRT that has been photographed in advance. As before, the length of this mark represents the size of the field of view. Next, another mark 5' is designated for the same tomographic imager. This mark 5' also has the same meaning as the mark 5 described above. By doing so, the tomographic planes 2, 2' newly photographed by the marks 5, 5' are perpendicular to the tomographic image 1, and have the center of view 8, 8' at the midpoint between the marks 5 and 5'. In this way, when multiple marks are made on the same tomographic image, simultaneous multiple tomography (
By using the multi-slice method (multi-slice method), it is possible to image all designated tomographic planes in one image capture. Furthermore, it is also possible to make any number of marks, one or more, on one tomographic image.

Furthermore, another embodiment of the present invention will be described using FIG. Marks 5, 5' representing tomographic planes 5, 5' to be newly imaged are specified using an arbitrary input device for the two tomographic images 1, 1' taken in advance. Then, the tomographic planes 2 and 2' to be newly photographed are perpendicular to the tomographic images 1 and 1', respectively, the size of the field of view is equal to the length of the marks 5 and 5', and the center of the field of view is at the marks 5 and 1', respectively. It is located at the center 8, 8' of 5'.

Similarly to the above, simultaneous multiple tomography allows imaging of all tomographic planes in one imaging. Furthermore, it is also possible to apply a plurality of marks to l tomographic images 1, or to apply a plurality of marks to one or more arbitrary tomographic images.

Still another embodiment of the present invention will be described with reference to FIG. A mark 5 representing a tomographic plane to be newly photographed is specified using an arbitrary input device for a tomographic image 1 that has been photographed in advance. This mark 5 may be a solid line or a broken line, but its length represents the size of the field of view, and its width represents the thickness of the tomographic plane. The tomographic plane 2 to be newly photographed is perpendicular to the tomographic plane 1, has a field of view center 8 at the center in the longitudinal direction of the mark 5, has a field of view size equal to the length of the mark 5, and is equal to the width of the mark 5. The fault plane becomes thick.

〔Effect of the invention〕

As is clear from the above explanation, according to the magnetic resonance imaging apparatus according to the present invention, if one takes precautions in this way, when trying to set the tomographic plane to be obtained, the center of the tomographic plane, i.e. Since the point to be positioned at the center of the display can be set, a new tomographic image can be obtained with the part to be observed mainly positioned at the center of the display by an extremely simple operation.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the MRI according to the present invention, FIG. 2 is an overall block diagram showing an outline of the MHI according to the present invention, FIG. 3 is a flow diagram showing the operation of the MRI according to the present invention, and FIG. 4 to 9 are block diagrams showing other embodiments of the MRI according to the present invention. 115...Central processing unit, 116...Display,
117...Keyboard, 118...Trackball.

Claims (1)

[Claims] 1. In a magnetic resonance imaging apparatus equipped with a display for displaying tomographic images, a first step of inputting coordinate information of each end point of a line or a virtual line that crosses the tomographic image on the display surface. a second means for inputting coordinate information of a point on the line; a third means for obtaining a tomographic image in a plane including the line and perpendicular to the tomographic image plane from the output of the first means; From the output of the second means, the third
A magnetic resonance imaging apparatus comprising: fourth means for positioning the one point on the tomographic image plane obtained by the means at the center point of the display. 2. The magnetic resonance imaging apparatus according to claim 1, wherein when a line that crosses a tomographic image on the display surface is input, coordinate information of both end points of the line can be automatically set. 3. The magnetic resonance imaging apparatus according to claim 1, wherein by inputting two points on the display surface, a virtual line that crosses the tomographic image on the display surface can be set. 4. The magnetic resonance imaging apparatus according to claim 1, wherein when a line or a virtual line that crosses the tomographic image is set on the display surface, the one point can be automatically set at the center of the line.