JP3933768B2 - Magnetic resonance imaging system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic resonance imaging apparatus (hereinafter referred to as an MRI apparatus) that obtains a diagnostic image using a nuclear magnetic resonance phenomenon that occurs in a living tissue of a subject.
[0002]
[Prior art]
When performing cardiac function measurement or an IVR procedure that introduces a biopsy instrument to the target affected area, the slice plane to be observed is determined, and continuous imaging is performed while executing a high-speed imaging sequence for the slice, and time series The images that change are displayed sequentially. As a premise of such continuous imaging, for example, when a biopsy instrument is introduced, it is necessary to determine a cross section including both the affected part to be introduced and the biopsy instrument. For this reason, in conventional MR imaging, first, several slice images are obtained in advance along a predetermined axis, for example, the body axis, and a slice plane for continuous imaging is determined from these slice images. At this time, if both of the affected part and the biopsy instrument are included in one slice surface of the slice image taken in advance, the slice surface or the affected part and the biopsy instrument are included. The slice plane orthogonal to the slice plane may be used as a slice plane for continuous shooting. However, when there are two measurement targets to be observed simultaneously on different slice planes, the slice plane is determined as follows.
[0003]
That is, as shown in FIG. 7, when two measurement targets B1 and B2 are on different images A1 and A2, and the slice planes passing through these measurement targets B1 and B2 are determined, the operator must select images parallel to each other. After selecting A1 and the image A2, the image A1 is displayed on the display, the position of the measurement target B1 is visually confirmed, and the approximate position is stored. Next, the image A2 is displayed on the display, and the position of the measurement target B1 confirmed by visual observation earlier is designated as B3 as one point for slice setting. A slice line C1 connecting two points of B3 and the measurement target B2 displayed on the image A2 is obtained and slice positioning is performed, and a slice plane passing through the line C1 and orthogonal to A2 and A1 is determined. Such a slice plane contains both measurement targets B1 and B2 on the image plane.
[0004]
[Problems to be solved by the invention]
However, when performing slice positioning according to such a procedure, the position of B3 (FIG. 7) on the image A2 depends on the memory of the operator, and it is extremely difficult to reproduce the exact position of the measurement target B1. Met. For this reason, only one of the measurement targets B1 can be displayed inaccurately. Therefore, even if slice positioning is performed based on this measurement target B1, the measurement target B1 is often not displayed on the photographed slice plane. . For this reason, the operator also has the disadvantage of having to repeat the B3 position determination and slice plane imaging processes many times.
[0005]
In view of such a problem, the present invention accurately grasps the position of a measurement target when selecting and determining a slice plane so as to include a plurality of measurement targets in the same plane, and this is determined on another image plane. An object of the present invention is to provide an MRI apparatus capable of accurately and easily performing slice positioning by accurately reproducing and displaying.
[0006]
[Means for Solving the Problems]
In order to achieve such an object, the MRI apparatus of the present invention stores a calculation means for calculating and reconstructing an image by processing a nuclear magnetic resonance signal sent from an MR imaging unit, and image data formed by the calculation means. In a magnetic resonance imaging apparatus comprising a storage means for displaying and a display means for displaying a result of the arithmetic processing performed by the arithmetic means, a first including a first measurement target among the image data stored in the storage means Means for selecting and displaying an image of the cross section of the first cross section and an image of the second cross section including the second measurement target and parallel to the first cross section, and position coordinates of the first measurement target in the first cross section Means for reading and storing; means for displaying a position corresponding to the position coordinates of the first measurement target on the second image; and the position of the first measurement target displayed on the second image and the second Determine the slice position from the measurement target Characterized by comprising a means for.
[0007]
When two measurement targets for determining the cross section exist on separate screens, the coordinates of one measurement target displayed on one cross section are stored and displayed on the other cross section. By selecting one measurement target displayed on the cross section and the other measurement target existing in the cross section, slice positioning can be performed very easily.
[0008]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 3 is a schematic configuration diagram showing an embodiment of the MRI apparatus of the present invention, in which an MR imaging unit that generates nuclear magnetic resonance in nuclear spins constituting a subject tissue and measures a nuclear magnetic resonance signal from the tissue. 31, a calculation unit 32 that performs calculation for image reconstruction on the nuclear magnetic resonance signals collected by the MR imaging unit 31, a storage device 33 that stores the calculation result in the calculation unit 32, and a display that displays the calculation result An apparatus 34 and an input unit 35 for inputting shooting conditions and the like to the calculation unit 32 are provided.
[0009]
The MR imaging unit 31 further comprises a static magnetic field generating magnetic circuit 2, a gradient magnetic field generating system 3, a transmitting system 4, a receiving system 5, and a sequencer 7, as shown in FIG.
[0010]
The static magnetic field generating magnetic circuit 2 generates a uniform static magnetic field around the subject 1 in an arbitrary direction. In addition to the high frequency coil 14 a, gradient magnetic field coil groups 9 a and 9 b that generate a gradient magnetic field and a high frequency coil 14 b that is a reception coil of the reception system 5 are disposed inside the static magnetic field generation magnetic circuit 2. The gradient magnetic field generation system 3 includes gradient magnetic field coil groups 9a and 9b having a configuration capable of independently applying gradient magnetic fields in Cartesian coordinate axis directions orthogonal to each other, and a gradient magnetic field power source for supplying current to the gradient magnetic field coil groups 9a and 9b. 10 and a sequencer 7 for controlling the gradient magnetic field power supply 10.
[0011]
The transmission system 4 has a high-frequency transmitter 11, a modulator 12, and an irradiation coil as a high-frequency coil 14a. In response to a command from the sequencer 7, the high-frequency pulse from the high-frequency transmitter 11 is amplitude-modulated by the modulator 12, and this amplitude modulation is performed. The object 1 is irradiated with a predetermined pulsed electromagnetic wave by amplifying the supplied high-frequency pulse through the high-frequency amplifier 13 and supplying it to the high-frequency coil 14a.
[0012]
The reception system 5 includes a high frequency coil 14b as a reception coil, an amplifier 15 connected to the high frequency coil 14b, a quadrature phase detector 16, and an A / D converter 17. When the high-frequency coil 14b detects the NMR signal from the subject 1, the signal is converted into a digital quantity via the amplifier 15, the quadrature phase detector 16, and the A / D converter 17, and at the timing according to the command from the sequencer 7. It is converted into two series of collected data sampled by the quadrature detector 16 and sent to a central processing unit (CPU) 8.
[0013]
The CPU 8 corresponds to the calculation unit 32 of FIG. 3 and performs operations such as Fourier transform on the collected data to reconstruct an image, and in addition to a sequencer 7, a transmission system 4, a reception system 5, and a signal processing system according to a predetermined program Each of 6 is to be controlled. The sequencer 7 operates based on a control command from the central processing unit 8, sends various commands necessary for collecting tomographic image data of the subject 1, a transmission system 4, and a gradient magnetic field generation system 3 of the static magnetic field generation magnetic circuit 2. And sent to the receiving system 5.
[0014]
Various data such as image data and arithmetic processing information formed by the CPU 8 are stored in a magnetic tape device 19 or a magnetic disk device 18 as a storage device (33 in FIG. 3), and a CRT display if necessary. 20 (display device 34 in FIG. 3).
[0015]
The input device 35 is for an operator to perform a desired operation such as input to the CPU 8, and as shown in FIG. 5, a keyboard 50, various function key groups 51 to 53, a trackball 54, an EL display 55, a rotary Input means such as an encoder 56 is provided. These input means together with the CRT display 20 constitute a console having a man-machine interface function.
[0016]
The function key group includes an image display function key group 51 for selecting functions related to patient selection and image display, an image analysis function key group 52, a measurement function key group 53 for setting measurement conditions, and the like. As will be described below, the slice plane can be set by operating these function keys and the trackball 54. The EL display 55 displays display contents necessary for the operation such as measurement conditions. The rotary encoder 56 is used to change the window / level of the image displayed on the CRT display.
[0017]
Next, an example of a procedure for performing slice positioning in the MRI apparatus having such a configuration will be described with reference to FIGS.
[0018]
In FIG. 1, A1 and A2 are diagrams schematically showing tomographic images of heads, which are images parallel to each other in different positions, which are measured in advance prior to the main measurement and stored in the storage device 33. Thus, the coordinates (for example, XY) on the display screen are images of the same field of view that are identical to each other. B1 and B2 are measurement targets included in the respective images. Now, a case where a slice including both measurement targets B1 and B2 is determined will be described with reference to the flowchart of FIG.
[0019]
When positioning a slice, first, the patient list key of the image display function key group 51 shown in FIG. 5 is operated to display a patient list on the CRT display 20, and a target patient is searched from among them. Is selected "(step 101). Next, a list of images of the corresponding patient is selected, and a pre-measured image is displayed on the display (step 102), and two plane images A1 and A2 including the measurement target B1 or B2 and parallel to each other are displayed. Is selected (step 103).
[0020]
Next, the measurement function key group 53 is operated to determine the slice position. The slice position can be determined by drawing a straight line that determines the slice plane on the displayed screen and selecting the angle or position with a trackball (hereinafter, straight line drawing method) or any two points. To select a slice plane passing through the two points (hereinafter referred to as the two-point method), and any of these methods may be set in advance. Is selected (step 104). As a selection method, a menu for selecting these methods may be displayed on the CRT display 20 by pressing a menu selection key, and a desired method may be selected using a trackball or a direction key. A function for selecting one of the methods may be assigned to a predetermined function key.
[0021]
When the two-point method is selected (step 105), one of the already selected images A1 and A2 is displayed on the display 20 and a marker M1 is displayed (step 106). The marker M1 may be anything that can be recognized as a marker, and can be moved to an arbitrary position by operating the trackball 54. Now, assuming that the image A1 is displayed, the marker M1 is set at the position of the measurement target B1. Next, the “point selection” is performed by pressing the M button for specifying the marker position (step 107). By this operation, the CPU 8 (calculation unit 32) reads the position coordinate of the measurement target B1 and stores it in the storage device 33.
[0022]
Subsequently, the image display function key group 51 displays the image A2 on the display 20 (step 108), and the M button for specifying the marker position is pressed. As a result, the marker M2 is displayed on the image A2. The marker M2 is displayed at the same coordinates as the marker M1 based on the position information stored in step 107 of the point selection of the marker M1. Therefore, the marker M2 indicates the measurement target B1 on the image A1.
[0023]
As described above, since the imaging of a plurality of slices performed as a premise of continuous imaging is performed along the same axis (for example, the Z axis) in the same field of view, the images A1 and A2 are parallel and the display screen thereof The upper coordinates (XY) match. Therefore, one point on the image A1 has the same position coordinate on the image A2, and by designating a predetermined coordinate on the image A1 displayed on the display, the point on the image A2 parallel to it is designated. A point with the same coordinates can be specified.
[0024]
In the state where the positions of the two measurement targets are displayed on the image A2 as described above, the “point determination” is performed by designating the coordinates of the measurement target B2 (step 109). Thus, the slice line C1 connecting the measurement target B1 and the measurement target B2 can be obtained, and the slice position is determined (step 110). After a series of procedures as described above, continuous measurement is performed on the positioned slice (step 111).
[0025]
When the straight line drawing method is selected as the slice position determination method, one of the already selected images A1 and A2 is displayed on the display 20 and the marker M1 is displayed as in the two-point method described above. (Step 206). Assuming that the image A1 is displayed, the marker M1 is set at the position of the measurement target B1, and the marker position is designated (step 207). By this operation, the CPU 8 (calculation unit 32) reads the position coordinate of the measurement target B1 and stores it in the storage device 33.
[0026]
Next, the other image A2 is displayed (step 208), and the M button for specifying the marker position is pressed. As a result, the marker M2 is displayed on the image A2. The marker M2 is displayed at the same coordinates as the marker M1, based on the position information stored in step 107 of point selection of the marker M1.
[0027]
In the straight line drawing method, as shown in FIG. 6, a straight line C1 passing through the marker M2 is displayed on the screen together with the display of the marker M2 (step 209). The operator operates the trackball or the like to change the position and angle of the straight line C1 so that the straight line C1 passes through both the marker M2 and the measurement target B2 (210). Thereby, the slice position passing through the measurement targets B1 and B2 is determined. After these procedures, continuous measurement is performed on the positioned slice (step 211).
[0028]
As described above, the MRI apparatus of the present invention stores the position of one measurement target displayed on the image of one cross section when determining a slice including two measurement targets existing on different cross sections in one plane. And since the position was displayed on the image of the other cross section, the slice containing two measurement targets can be determined reliably. Therefore, the subsequent continuous measurement can be quickly executed.
[0029]
In addition, each step of the said Example can be changed arbitrarily in the range of the meaning of this invention. For example, in the above embodiment, after step 107 for “point selection” of the measurement target B1 on the image A1, the display of the image A2 and the marker M2 display operation are performed respectively, but at the same time as the display of the image A2. That is, the marker M2 can be displayed on the image A2 without separately operating the M button for displaying the marker M2.
[0030]
In the embodiment described above, the trackball is used for the operation of the marker and the line C1, but a directional key on the keyboard, a mouse, a joystick, or the like may be used. In addition, an input device having a special image display function key group 51 and a measurement function key group 53 was used. However, these functions can be operated with a normal keyboard 50, and each operation key and operation button can be set to other functions. Needless to say, the configuration of the keyboard and the like of the input device and the key operation of the operator on the input device can be arbitrarily changed, for example, using a key or a mouse.
[0031]
Further, in the above embodiment, the case where two selected points are on different parallel images and the field of view of the images is the same has been described. However, the present invention can be applied even when the fields of view are different. In this case, the step of reading the position coordinates of the marker M1 on the A1 image in the process of “point selection” (107, 207) and the step of displaying the position coordinates of the marker M1 on the coordinate plane of the A2 image (108, 208). ) Between the two coordinates may be inserted.
[0032]
【The invention's effect】
As described above, the MRI apparatus of the present invention includes means for reading and storing the position coordinates of the first measurement target on the first image, and the position coordinates of the first measurement target on the second image. And means for positioning the slice from a straight line connecting the first measurement target and the second measurement target displayed on the second image, on the second image plane. The position coordinates of the first measurement target can be accurately displayed together with the second measurement target. As a result, it is possible to accurately and easily position the slice including two measurement targets on different cross sections. There is an effect. Furthermore, when performing continuous imaging, it is possible to facilitate imaging of MRI images including a plurality of measurement targets on the same imaging plane.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of an embodiment using an MRI apparatus of the present invention.
FIG. 2 is a flowchart showing a slice positioning procedure using the MRI apparatus of the present invention.
FIG. 3 is an overall block diagram showing an embodiment of an MRI apparatus according to the present invention.
FIG. 4 is a schematic configuration diagram showing an embodiment of the MRI apparatus of the present invention.
FIG. 5 is a diagram showing an embodiment of an input device in the MRI apparatus of the present invention.
FIG. 6 is an explanatory view of another embodiment using the MRI apparatus of the present invention.
FIG. 7 is an explanatory diagram of an embodiment using a conventional MRI apparatus.
[Explanation of symbols]
31 …… Shooting device
32 …… Calculation unit
33 …… Storage device
34 …… Display device
35 …… Input device

Claims (3)

An arithmetic means for processing the nuclear magnetic resonance signal sent from the MR imaging unit to reconstruct an image, a storage means for storing image data formed by the arithmetic means, and a result of the arithmetic processing by the arithmetic means are displayed. In a magnetic resonance imaging apparatus comprising a display means,
Of the image data stored in the storage means, an image of a first cross section including a first measurement target, an image of a second cross section including the second measurement target and parallel to the first cross section, and Means for selecting and displaying, means for reading and storing the position coordinates of the first measurement target in the first cross section, and means for displaying the position corresponding to the first measurement target on the second image And, from the line connecting the position of the first measurement target displayed on the second image and the second measurement target , a slice plane including the line and perpendicular to the first cross section and the second cross section A magnetic resonance imaging apparatus comprising: means for determining a slice position . The magnetic resonance imaging apparatus according to claim 1,
The means for determining the slice position comprises input means for accepting designation of a desired position on the displayed screen, and the position of the first measurement target on the second image designated by the input means A magnetic resonance imaging apparatus, wherein a plane including a line passing through a position of a second measurement target is determined as a slice plane. The magnetic resonance imaging apparatus according to claim 1,
The means for determining the slice position includes input means for receiving a selection of a position change including drawing of a straight line on the screen and rotation and movement of the straight line, and a plane including the position of the straight line selected by the input means. A magnetic resonance imaging apparatus characterized in that it is determined as a slice plane.

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