JP2003126063A - Method of imaging for alignment for mri and mri apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform an accurate alignment for a diseased area with a MRI without complicating alignment procedures using an image for alignment and without increasing time for alignment. SOLUTION: A MRI apparatus is equipped with a means to prepare an image for alignment of two intersecting slice planes depending on a desired imaging area of a subject, a means to display two prepared images for alignment, a means to specify an imaging range in two directions among the read direction, the encode direction, and the slice direction on an image for alignment out of two displayed images for alignment and to specify an imaging range in the remaining direction among the three directions on the other image for alignment, and a means to take the number of the images, corresponding to the specified imaging range in the slice direction, of a slice including a region corresponding to the specified imaging range in the read and encode directions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses two positioning images (hereinafter referred to as a parent image) in MRI (Nuclear Magnetic Resonance Imaging), and a slice diagnostic image (hereinafter referred to as a parent image) at the time of actual imaging. , And a MRI apparatus, in which a photographing position of a child image is preset and photographed.

[0002]

2. Description of the Related Art Conventionally, as a positioning and photographing method in MRI, a method using a light projector and a method using a parent image are known. Among them, as a method of using a parent image, a method called "CROSS (cross) plan" and a method called "SAME (same) plan" using one parent image are known. .

Among these, the CROSS plan is for photographing by specifying in advance the position of a child image orthogonal to the parent image. As shown in the example of head imaging in FIG. 16, this is to specify the image center position in the lead direction, the imaging range, and the number of slices while viewing the sagittal image that is the parent image in FIG. 16A on the monitor screen. At the same time, as the image center position and range in the encoding direction, an appropriate numerical value is commanded by calculation, and the actual photographing is performed based on these command information. As a result, a plurality of child images that are orthogonal to the parent image of FIG. Also, this C
In the ROSS plan, the axial image (child image) of FIG. 18B is obtained from the coronal image (parent image) of FIG. 18A similarly in the case of abdominal imaging.

On the other hand, in the SAME plan, the position of the child image parallel to the parent image is designated and photographed. As shown in the example of head imaging in FIG. 20, this is to specify the image center position and the imaging range in the read direction and the encoding direction while viewing the axial image (parent image) in FIG. 20A on the monitor screen. At the same time, the slice position parallel to the axial image and the imaging range (the number of slices) are specified by the operator's calculation. As a result, at the time of actual photographing, a plurality of axial images (child images) shown in FIG.

Regarding the method of setting the image center position in the encoding direction, the method of matching the image center position with the system center, the method of setting the slice position of the parent image in the encoding direction as the image center position, and the method of designating a numerical value. However, the CROSS plan and the SAME plan described above are one form of such a numerical designation method.

[0006]

However, according to the positioning photographing method using the CROSS plan based on the one parent image described above, the image center position and the photographing range in the lead direction (or the encode direction) can be specified. , There is a situation where the image center position in the encoding direction (or the reading direction) and the shooting range cannot be specified while confirming on the screen (when the encoding change is performed, the encoding direction and the reading direction are replaced). As described above, various inconveniences have occurred.

First, the case of head imaging according to the CROSS plan will be described with reference to FIG. The operator is
Although it is possible to specify the image center position in the lead direction and the shooting range while viewing the parent image (sagittal image) shown in FIG. 6 (a) on the monitor screen, while confirming with the operator's eyes on the monitor screen. It is impossible to specify the image center position and the shooting range in the encoding direction.

Therefore, for the purpose of shortening the scan time, a technique of varying the image range in the encoding direction (for example, rectangular FOV (Field of View) method, arbitrary matrix method) is used, and the parent image of FIG. Currently, the operator's experience relies on how small the range in the encoding direction may be made when a child image is designated. In other words, the range is specified by inputting a numerical value that relies on the intuition when planning a shooting based on the parent image. If the value is too small, folding artifacts will occur as shown in FIG. On the other hand, if a large numerical value is entered for safety, aliasing artifacts are avoided, but the original purpose of the arbitrary matrix method such as shortening the scan time is halved.

By the way, in the plan of FIG. 16, the center of the subject in the encoding direction may deviate from the center of the screen. To improve the positional deviation, the positioning photographing method based on FIG. 17 is adopted. There is also. That is,
As shown in FIG. 17 (a), first, an axial image of the head is taken, the midline of this axial image is designated while looking at the monitor screen, and then the sagittal image of the midline is again designated (see FIG. b)) is taken as a positioning image. Then, while looking at the monitor screen of this sagittal image (at this time, there is no axial image screen), an imaging plan is made by the method of FIG. 16 described above, at which time the center position in the lead direction and the imaging range are specified. At the same time, the center position of the image in the encoding direction is designated. As a result, FIG.
As shown in (c), the center of the axial image can be made to substantially coincide with the center of the screen.

However, in obtaining the axial image of FIG. 17 (c), although it is possible to align the center positions, the photographing plan performed at the stage of monitoring FIG. 17 (b) will be described with reference to FIG. Similarly, it is still impossible to specify the image center position in the encoding direction and its shooting range. That is, using a method such as a rectangle FOV,
As described above, there are problems that artifacts are generated due to folding back (see FIG. 7C) and the scan time is extended. Furthermore, since the procedure of photographing an axial image and designating the median line of the axial image is added as a pre-stage of the photographing plan, the problem that the whole procedure of the photographing plan becomes complicated and takes time is derived.

Further, the case of abdominal imaging according to the CROSS plan will be described with reference to FIG. While the operator can specify the image center position in the lead direction and the photographing range while viewing the coronal image (parent image) of the abdomen shown in FIG. 18A on the monitor screen, the operator encodes on the monitor screen. It is impossible to specify while confirming the image center position in the direction and the shooting range. For this reason,
Regarding the axial image obtained as shown in FIG. 16B, the same problem as in the case of FIG. 16 occurred.

In order to make the center of the subject in the encoding direction and the center of the screen in the axial image of FIG. 18 (b) substantially coincide with each other, a two-step positioning method shown in FIG. 19 may be adopted. That is, as shown in FIG. 19A, an axial image of the abdomen is first taken, the center line of this axial image is specified while looking at the monitor screen, and then the coronal image of the center line (FIG. (B)) is photographed as a positioning image. Then, while looking at the monitor screen of the coronal image (there is no screen of the axial image at this time), a photographing plan is made by the method shown in FIG. At that time, the center position in the read direction and the photographing range are specified, and the image center position in the encode direction is specified. As a result, the center of the axial image can be made to substantially coincide with the center of the screen as shown in FIG. However, also in this case, the same problem as the positioning described in FIG. 17 remains. FIG. 19C shows the case where the folding artifact occurs.

On the other hand, even in the above-mentioned SAME plan (see FIG. 20), there is no problem in designating the shooting range and the center position of the child image in the read direction and the encode direction, but the slice range is displayed on the monitor screen. It cannot be confirmed visually. In other words, since the specification of the slice range of the child image depends on the intuition of the operator, the number of slices,
Depending on how the slice thickness, slice gap, etc. are selected, the slice range may deviate from the lesion D, as shown in FIG. 21, and it may not be possible to truly cover the region to be imaged. In such a case, it is necessary to take the image again.

The present invention has been made in view of the problems of the conventional method, and the operator does not complicate the positioning procedure using the parent image and hardly increases the positioning time, and the operator can perform the lesioned part. It is an object of the present invention to provide a positioning imaging method capable of performing reliable positioning with respect to the MRI apparatus and an MRI apparatus capable of implementing this imaging method. In particular, when the arbitrary matrix method or the like is used, an artifact due to folding back does not occur in the child image, and
Provided are a positioning imaging method capable of shortening a scanning time and an MRI apparatus capable of implementing this imaging method. Furthermore, in particular, a positioning photographing method for improving the operation efficiency of the operator and this photographing method can be implemented M
An RI device is provided.

[0015]

In order to achieve the above-mentioned object, the MRI apparatus according to the present invention has, as one aspect,
Positioning image preparing means for preparing positioning images for two intersecting slice planes according to a desired imaging region of the subject, and 2 prepared by this positioning image preparing means
Display means for displaying one positioning image, and two directions of a read direction, an encoding direction, and a slice direction on one of the two positioning images displayed by the display means. And a shooting range designating means for designating a shooting range in the remaining one of the three directions on the remaining positioning image.
And a main photographing unit for photographing the slices having the areas corresponding to the photographing ranges in the read direction and the encoding direction designated by the photographing range designating unit in the number corresponding to the photographing range in the designated slice direction. Is characterized by.

According to another aspect of the present invention, a positioning image preparing means for preparing positioning images of two intersecting slice planes according to a desired imaging region of the subject, and the positioning image preparing means. Display means for displaying the two positioning images prepared by the image preparing means, and one of the two positioning images displayed by the display means, in the read direction and the encoding direction. A range can be specified, and an imaging range of one of the read direction and the encoding direction and the slice direction can be specified on the remaining positioning images, and the imaging range can be specified on the two positioning images. And a photographing range designating means for finally designating a photographing range in the read direction, the encoding direction, and the slice direction, and the photographing range designating means. The slices having a region corresponding to the imaging range of the read direction and the encoding direction that, number of sheets in accordance with the imaging range of the specified slice direction, characterized by comprising a main imaging means for photographing.

Furthermore, according to the present invention, as another aspect, there is provided a positioning imaging method in magnetic resonance imaging, which is performed by a magnetic resonance imaging apparatus to determine an imaging position of a subject and obtain an image of the imaging position. It This positioning imaging method uses the magnetic resonance imaging apparatus according to (i) 2 according to a desired imaging region of the subject.
Prepare the positioning images of the intersecting slice planes, and
i) Display the two positioning images prepared, (ii)
i) Of the two displayed positioning images, one of the positioning images specifies the shooting range in two directions of the read direction, the encoding direction, and the slice direction, and the remaining positioning images are used. An imaging range in the remaining one of the three directions is specified on the image, and (iv) a slice having an area corresponding to the imaging range in the specified read direction and encoding direction is acquired in the specified slice direction. It is characterized in that the image at the photographing position is obtained by operating so as to photograph the number of images corresponding to the range.

[0018]

According to the MRI apparatus and the positioning photographing method executed by the apparatus according to the present invention,
At the time of positioning, two intersecting positioning images that are set in advance according to the desired imaging region are prepared.
The two positioning images are, for example, images of two orthogonal slice planes, and are prepared by simultaneously (for example, by multi-angle / multi-slice imaging) or sequentially by individually imaging both images. It Further, the two orthogonal slice planes are, for example, an axial image and a sagittal image when the imaging region is the head, and an axial image and a coronal image when the imaging region is the abdomen.

Next, the operator designates the information for defining the photographing range, for example, while viewing the two positioning images thus prepared on the monitor screen. At this time, as an example, the image center position and the image range (shooting range) in the read direction and the encode direction of the slice image at the time of actual shooting are specified on one of the two positioning images. And on the other positioning image,
A shooting range in the slice direction (the number of slices, a slice range in the slice direction, etc.) for the main shot image is designated.

Further, in the invention described in claim 2, in particular, on one of the positioning images, the shooting range in the lead direction or the encoding direction at the time of actual shooting is specified, and on the other positioning images, It is also possible to specify the shooting range in the encode direction or the read direction and the shooting direction at the time of the main shooting together. The shooting range in the read direction or the encode direction may be set using either one of the one and the other positioning images, or may be set using both.

In this way, while checking the two positioning images photographed easily and in a short time on the monitor screen,
The attributes of the image of the slice to be photographed (the photographing range and position in each direction) intended by the operator are accurately specified. Images of a desired number of slices are taken according to this designation information.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will now be described with reference to FIGS.
A description will be given based on FIG.

The MRI system shown in FIG. 1 includes a magnet section for generating a static magnetic field, a gradient magnetic field section for generating a gradient magnetic field for giving positional information to the static magnetic field, and a transmitting / receiving section for magnetic excitation and NMR signal reception. It functionally has a receiving unit and a control / arithmetic unit.

Specifically, the magnet section is, for example, a normal conducting magnet 1 and a static magnetic field power supply 2 for supplying a current to the magnet 1.
And a static magnetic field H in the z-axis direction of the opening in which the subject P enters.
Generates ₀ . Further, the gradient magnetic field unit is composed of three pairs of gradient magnetic field coils 4 ... 4 incorporated in the magnet 1 in the x, y and z directions.
(Only a part thereof is shown), and these gradient magnetic field coils 4 ...
Drive circuit 5 and gradient magnetic field control device 6 for supplying current to 4
And a gradient magnetic field power source. Gradient magnetic field controller 6
Activates the drive circuit 5 according to the pulse sequence supplied from the main controller 7. As a result, in order to provide position information for imaging, a linear magnetic field is superimposed on the static magnetic field H ₀ to form a gradient magnetic field. The transmission / reception unit includes a transmission coil 8a and a reception coil 8b arranged to face the subject P in the opening of the magnet 1, and a transmitter 9 individually connected to the transmission coil 8a and the reception coil 8b. And a receiver 10. The transmitter 9 generates a high frequency pulse for exciting NMR based on a command from the control device 7. The receiver 10 detects and amplifies the NMR signal obtained by the coil 8b, and sends the NMR signal to the storage device 11 based on a command from the control device 7.

Further, the control / arithmetic unit includes a control device 7 connected to the transmitter 9, the receiver 10 and the gradient magnetic field control device 6, a storage device 11 for storing an NMR signal, and an operation command to the control device 7. And an arithmetic unit 12 for processing the stored signal of the storage unit 11, and a display unit 13 for display.
With. An input device 14 such as a keyboard is connected to the arithmetic unit 12. The arithmetic unit 12 subjects the acquired NMR signal to a huge amount of arithmetic processing including Fourier transform and the like to generate image data. This image data is displayed on the display device 13 as needed.

The storage device 11 stores, as one of fixed data, a procedure capable of controlling from a predetermined photographing plan to actual photographing, and when the system is started,
It is called into the work area of the arithmetic unit 12. Therefore, according to the procedure, after the positioning, for example, multi-slice imaging based on the selective excitation method is performed in a gapless manner, while displaying a message on the display device 13 and performing a necessary dialogue with the operator. Based on the results, it is designed to digest the prescribed procedure.

Next, the operation and effect of this embodiment will be described with reference to FIGS.

First, an example of a procedure from positioning to actual photographing (including preparation by only an operator) will be described with reference to FIG. First, place the patient on the tabletop (step 2 in Figure 2).
0), straighten the patient, and use the light from the projector to adjust it to the Z-axis and X-axis reference positions (step 2 in the figure).
1). Next, an RF coil suitable for the imaged site is set on the mount (step 22 in the figure). The whole-body coil is already installed on the mount. After the installation of this RF coil, the patient is inserted into the pedestal for each tabletop (step 2 in the figure).
3) After this, the operator uses the input device 14 to perform patient registration such as patient name, date of birth, and measurement position (procedure 24 in the figure).

When these preparations have been completed, the operator commands the input device 14 to capture a positioning image (step 25 in the figure). By this command, the images of the parent images for positioning are sequentially or simultaneously displayed on the monitor screen of the display device 13. Therefore, the operator makes a shooting plan while visually observing those parent images, and the child images for the main shooting are made. Attribute data relating to the positioning of the is input from the input device 14 (step 2 in FIG.
6). When this input is completed, the actual shooting is automatically performed (step 27 in the figure).

Of the above procedures, procedures 25 to 27, which are photographing routines including positioning, will be described in more detail with reference to FIG. The arithmetic unit 12 determines in step 30 of FIG. 3 whether or not to take a positioning image, based on a command from the operator. In the case of NO in this determination, the arithmetic unit 12 waits while repeating the determination, but YES
In the case of, the processing of steps 31 and 32 is sequentially performed. Of these, the imaging region information is input in step 31, and step 3
In step 2, it is determined whether the input is completed.

When the determination in step 32 is YES, the arithmetic unit 12 shifts the processing to step 33, and the processing unit 12 clinically matches the preset imaging region.
One designated slice plane is called from the storage device 11. For example, when the imaging region instructed in step 31 is the head, the axial plane and the sagittal plane orthogonal to each other are called (see FIG. 4), and in the case of the abdomen, the axial plane and the coronal plane orthogonal to each other (see FIG. 5). ) Is called.

Then, the processing shifts to step 34, and the arithmetic unit 12 takes the two slice planes designated in step 33 by using the multi-angle / multi-slice method in order to obtain the positioning image. Send a command to. With this one-time imaging, tomographic images of two slice planes can be obtained at the same time. This tomographic image is used as a parent image for positioning, and in this embodiment, the axial image A and the sagittal image S shown in FIGS. 6A and 6B are obtained at the time of head imaging, and the axial image A at the time of abdominal imaging is obtained. 7 (a)
An axial image A and a coronal image C shown in (b) are obtained. These images are temporarily stored in a predetermined area of the storage device 11.

After the parent image as the positioning image is prepared in this way, the arithmetic unit 12 performs steps 35 to 37.
Process. As a result, in step 35, one of the two parent images (for example, the axial image A when the head is photographed) is displayed on the display device 13. And
In step 36, the operator sets a ROI (region of interest) on the screen while looking at the displayed parent image (axial image) to make a photographing plan, and specifies attributes of the child image to be photographed (axial). In the case of an image, data e regarding the image center position and range in the encoding direction and data r regarding the image center position and range in the reading direction: see FIG. 6A. Next, in step 37, it is judged whether or not the input of one of the attributes is completed, and if YES,
The processing of steps 38-40 is performed.

Of these, in step 38, the photographed 2
The remaining parent image (sagittal image S at the time of photographing the head) of the one parent image is displayed on the display device 13. In step 39, the operator sets a ROI (region of interest) on the screen while looking at the displayed parent image (sagittal image) to make a photographing plan, and specifies the remaining attributes of the child image to be photographed ( Data s regarding the slice range in the slice direction and the number of sheets in the sagittal image: see FIG. 6B).
Next, at step 40, it is judged whether or not the input of the remaining attributes is completed, and if YES, the main photographing at step 41 is instructed.

The main photographing in step 41 is performed by, for example, conventionally well-known multi-slice photographing, and an axial image (for example, FIG. 6) as a plurality of child images is obtained by one scan.
(See (c)) is obtained, and these image data are stored in the storage device 11 and displayed on the display device 13.

On the other hand, when the abdominal imaging is instructed in step 31 described above, in this embodiment, the axial image A and the coronal image C (FIGS. 7A and 7B) of the abdomen which are perpendicular to each other are used as parent images for positioning. (See) is simultaneously photographed (steps 33 and 34). Then, on these images, for the axial image A, the data e and r relating to the image center position / range in the encoding direction and the reading direction are R.
Each is designated through the OI, and for the coronal image C, data s regarding the range in the slice direction and the number of sheets is designated by the ROI (steps 36 and 39). Therefore, in the actual shooting, as shown in FIG. 7C, a specified number of axial images as child images determined by the specified attributes are obtained.

As described above, two parent images orthogonal to each other are obtained at the same time, a photographing plan is made while viewing the parent images on the monitor screen, and the attributes of the child images to be photographed are designated. In other words, when specifying the attribute of the child image, two parent images that are in a complementary relationship with each other can be used, and the attribute is set to RO.
It can be performed almost completely while checking on the screen using I. For this reason, it is possible to eliminate the procedure of relying on part of the attributes as in the conventional method, so that it is possible to surely match the image centers with each other and to accurately capture the lesion by accurately specifying the attributes. In addition, it is possible to prevent artifacts due to aliasing when the encoding range is too narrow, and it is possible to shorten the scan time by utilizing the encoding range variable technique such as the arbitrary matrix method or the rectangular FOV.

Further, since the two parent images for positioning are photographed at the same time in one photographing, the time for the positioning photographing is almost the same as the conventional method, and the procedure for the positioning photographing is not complicated. The entire inspection related to the method can be performed quickly and smoothly, and the burden on the operator can be reduced.

Note that the attributes of the child images that can be designated based on the above-described two parent images are summarized in FIG. 8 (however, when performing an encode change, the encode direction and the read direction are replaced). . according to this,
In the sagittal image (head photographing) and the coronal image (abdomen photographing), which are parent images, in addition to the slice direction range, the lead direction range (FOV) and the center position can be specified (in the figure, “ "Yes" indicates that it can be specified, and "No" indicates that it cannot be specified). Therefore, in the present invention, the range (FO) in the encoding direction from one parent image (axial image)
V) and the center position may be designated, and the range in the lead direction and the center position and the range in the slice direction may be designated from the other parent image (sagittal image, coronal image).

Next, a second embodiment will be described with reference to FIGS. The MRI system according to the second embodiment performs positioning imaging in consideration of the saturation method. The hardware system configuration is the same as that of the first embodiment.

The saturation method respirations by suppressing the generation of MR signals from a specific portion of the object to be imaged.
It eliminates artifacts and blood flow artifacts caused by body movements. For example, when a sagittal image of the cervical spine is captured, as shown in FIG. 9A, the swallowing artifact DG may overlap the desired portion of the image, making diagnosis impossible. In order to avoid this, in the saturation method, the saturation region is positively designated so as to cover the portion where the artifact is generated. As a result, for example, as shown in FIG. 9B, the portion where the saturation region ST is set appears black on the diagnostic image. However, MR from the site of swallowing movement
Signal generation can be blocked and artifacts can be eliminated.

Below, an example of a positioning photographing procedure and an image example in which the above-mentioned saturation method is added will be explained based on FIG. 10 and FIG. In addition, here, FIG.
The procedures described are carried out as well. Further, in the procedure shown in FIG. 10, the same or equivalent steps as those in FIG. 3 are designated by the same reference numerals, and detailed description thereof will be omitted.

When it is decided that the positioning image is to be taken by the arithmetic unit 12 (step 30 in FIG. 10), step 3 is executed.
In step 1, for example, "cervical vertebra" is read as the imaging region information. When this input is completed (step 32), the information of the two designated slice planes corresponding to the imaging region “cervical spine”, which is predetermined in step 33, is called. For the cervical spine, the two designated slice planes are, for example, a sagittal plane and a coronal plane. When the slice plane is determined, the arithmetic unit 12
In step 34, the sagittal image S and the coronal image C, which are parent images for positioning, are photographed by using, for example, the multi-angle multi-slice method and the two-dimensional Fourier transform method.

Next, in step 35, the arithmetic unit 12 obtains the sagittal image S, which is one of the parent images, as shown in FIG.
Is displayed on the display device 13. After this, step 35
Go to A and specify that the saturation method is applied. As a result, information on the saturation region is also required as an attribute that the child image shot in the main shooting should have. Therefore, in step 36, the operator looks at the displayed sagittal image S while watching the ROI.
By setting a, the shooting range in the encoding direction (FO
V) The ED and the center position of the region, the photographing range (FOV) RD in the lead direction and the center position of the region are designated, while the region of interest ROIb is designated to designate the saturation region ST. Since the saturation region is limited to a slab-like shape in principle, the designation is made by specifying the thickness of the slab, the position of the slab, the inclination angle of the slab, and the number of slabs (combining multiple slabs as shown in Fig. 12 There is also).

When the designation of the attributes of the child image in the one parent image is completed (step 37), the coronal image C, which is the other parent image, is displayed in step 38 in FIG.
Display as shown in (b). Next, in step 39, the operator uses the region of interest ROIc while looking at the displayed coronal image C and selects the desired slice region SL.
Specify as an attribute in the slice direction.

When this designation is completed (step 40), the process proceeds to step 41, and a diagnostic image is photographed according to the attributes designated in steps 36 and 39. This imaging is performed here based on the multi-slice method and the two-dimensional Fourier transform method. As a result, as shown in FIG. 11C, the number of sagittal images (child images) specified by the number of slices is obtained by one scan.

These child images have the same image range as the photographing range in the encoding direction and the reading direction designated on the parent image S, and the center position of the image is at the center position of the monitor of the display device 13. I am doing it. As a result, it is possible to obtain the same effect as that of the above-described first embodiment that a child image with high positioning accuracy is obtained based on the positioning as intended by the operator without relying on intuition or experience. In addition, in this embodiment, since the MR signal is not received from the portion of the saturation region ST designated on the parent image S, the slab-shaped region ST is displayed in black, and instead, the swallowing motion is caused. The resulting artifact can be eliminated from the child image, and the image quality can be improved and the diagnostic ability can be improved.

Note that the attribute designation of the child image to which the saturation method is applied is not limited to the above-described cervical spine imaging, but can be applied to the imaging of any diagnostic site. Also,
It goes without saying that the slice planes of the two parent images can be arbitrarily selected according to the diagnosis region. Further, in the above-described embodiment, the case where the saturation position is designated by only one parent image has been described, but the saturation region can be set by each of the two parent images.

Further, in each of the above-described embodiments, the two parent images are sequentially displayed and the required attributes are designated each time, but this method is suitable when the monitor screen is small. On the other hand, if the monitor screen is large enough, the two parent images are split and displayed on one monitor screen so that both attributes can be specified on the same screen without updating the screen. May be.

Further, in the above-described embodiment, the two parent images are simultaneously photographed by the multi-angle / multi-slice photography. However, although this slightly extends the photography time, it is possible to separately photograph them by normal photography. May be.

Further, in each of the above-described embodiments, the two parent images are orthogonal images, but they do not necessarily have to be orthogonal and the attributes of the encoding direction, the reading direction and the slice direction are designated. If possible, the oblique slice planes may be inclined to each other.
Further, the designation of the two slice planes is not limited to the above-described head and abdominal radiography, but is determined in consideration of the clinical aspect according to the radiographed region.

Further, a third embodiment will be described with reference to FIGS. The third embodiment provides a positioning photographing method capable of accurately designating a photographing range without displaying one of the parent images on the display device and looking at the screen.

The principle of positioning in the third embodiment will be described. A region (profile) where a subject exists in the encoding direction and the reading direction can be detected without capturing an image. FIG. 13 shows a state in which the abdomen of the patient P is inserted into the magnet bore BR. The center of the radial cross section of the bore BR is set to the system center O (origin), the X axis (horizontal axis in the figure) passing through this system center O is the read direction, and the Y axis (vertical axis in the figure) is encoded. As a direction, its coordinate system is set as shown. In this state, the profile Py in the Y-axis direction is obtained by applying the read gradient magnetic field in the Y-axis direction without applying the encode gradient magnetic field and performing Fourier transform on the collected MR data. The profile Px in the X-axis direction is obtained by applying the encode gradient magnetic field in the X-axis direction without applying the read gradient magnetic field and performing Fourier transform on the collected MR data. The origin (reference point) in the X-axis direction and the Y-axis direction is uniquely determined corresponding to the system origin O. Therefore, even if the abdomen of the patient P is displaced from the system center P as shown in the figure, the profiles Px, P in the respective axial directions are obtained.
Differences Δx and Δy between the center position of the half width of y and the origin O of each axis
Thus, the center position of the shooting range (that is, the center position at the time of image reconstruction) can be defined. Further, the length of the imaging range (FOV) in the encoding direction and the reading direction can also be determined using the half-value widths of the profiles Px and Py.

Next, an example of the procedure of positioning and photographing executed by the arithmetic unit 12 will be described with reference to FIG.

Steps 50 to 52 in FIG. 14 are the same as the steps 30 to 32 described in FIG. In step 51, it is assumed that the abdomen is designated as the information of the part to be imaged.

Next, the arithmetic unit 12 sequentially executes the processings after step 53. In step 53, first, a slice plane (for example, a coronal plane for the abdomen) capable of designating a slice direction attribute of a child image to be described later is set.
In this step, the slice plane of the other non-displayed parent image is also automatically determined according to a predetermined procedure. Next, in step 54, the encoding direction is set to a predetermined axial direction (for example, the Y-axis direction). In this step, it is automatically determined which axial direction the lead direction should be. Then, in step 55, a parent image along the set slice plane is captured.

After that, the process proceeds to step 56, the profile data Px and Py in the encode direction and the read direction are collected as described above, and the data is temporarily stored in the storage device 11. And step 57
Then, based on the stored profile data Px, Py, the half width of the profile in the encoding direction (here, the Y-axis direction) and the read direction (here, the X-axis direction) and the differences Δx, Δy from the system center O are calculated. Of the calculated data, the half width in each direction is multiplied by a predetermined coefficient (for example, 1.1) in step 58. This is to ensure that a slight margin is provided between the photographic range (FOV) in each direction and the subject, so that aliasing artifacts are reliably avoided.

After the above arithmetic processing is completed, at step 59, the parent image (here, the coronal image C) already taken at step 55 is displayed as shown in FIG. 15A, for example. Next, at step 60, the slice range (attribute in the slice direction) intended by the operator is set to the region of interest ROI.
Specified by setting d. At this time, in this embodiment, not only the slice direction but also the read direction attribute is specified by using the coronal image C that is the parent image. That is, when the region of interest ROId is displayed by the preset default function, the region of interest R
The center position of the OId is displayed at the center of the subject in the lead direction (center of the profile Px), and the length L _R of the region of interest ROId in the lead direction is calculated based on the profile data Px (that is, It is automatically set to a value obtained by multiplying the value obtained by doubling the half-value width by a coefficient). As a result, the center position of the imaging range in the read direction and the range are automatically set in accordance with the attribute setting in the slice direction, and the setting state can be visually confirmed.

When the end of this attribute setting is confirmed in step 61, the process proceeds to step 62, and a child image for diagnosis is photographed by, for example, the multi-slice method. This imaging is performed based on the center position of the imaging range in the encoding direction and the reading direction calculated by the processing up to step 58 and its range, and the slice range input in step 60. As a result, the center position of the designated imaging range becomes the center position at the time of image reconstruction, and the abdominal axial image having the designated FOV image range is obtained by the number of designated slices (see FIG. 15B). ).

As described above, unlike the above-described two embodiments, it is not necessary to display the parent image relating to the attribute setting of the encoding direction and the reading direction, and the automatic setting can be surely performed by the calculation in the system from the profile data. For this reason,
It is better to set only the attribute in the slice direction using the parent image. The attribute in the read direction can be visually confirmed by the operator when setting the attribute in the slice direction.

As a result, according to the third embodiment, the parent image need only be displayed once, and the attribute setting need only be done once in the slice direction, so that the operation becomes easy and the operator's operation labor is reduced. There is an advantage. Also, especially regarding the center position of image reconstruction in the encoding direction,
The method of substituting the slice position in the encoding direction of the parent image or the center position of the system is unnecessary. As a result, similar to the above-described two embodiments, the center position of the subject can be reliably aligned with the center position of the FOV on the screen, and the subject can be accurately accommodated within the range of the FOV in the encoding direction, and aliasing artifacts can occur. Can be prevented.

In the third embodiment described above, the automatic setting function of the photographing range (the range and the center position) can be provided only in the encoding direction if necessary.

[0063]

As described above, according to the present invention, two positioning images which intersect each other and which are preset according to a desired region to be imaged are prepared, and these two positioning images are prepared. While viewing on the monitor screen, the information specifying the imaging range within the subject is specified, and the image of the desired number of slices is main-photographed according to the specified information. Therefore, for example, while the operator visually checks the two positioning images, for example, the attributes of the encoding direction and the reading direction are designated on one of the positioning images, and the attributes of the slice direction are designated on the remaining positioning images. Can be specified. Further, for example, the attributes of the encoding direction or the reading direction may be designated on one of the positioning images, and the attributes of the reading direction or the encoding direction and the slice direction may be designated on the remaining positioning images. As a result, it is possible to accurately specify the imaging ranges in the three directions by using the two positioning images that intersect each other, so that it takes no special time to prepare the positioning images, and the positioning procedure can be complicated. Without, since it is possible to eliminate the part relying on the operator's intuition in the positioning procedure, it is possible to prevent the occurrence of folding artifacts due to the ambiguity of the positioning, and
The scanning time can be shortened by making full use of a technique such as an arbitrary matrix method, and the entire positioning imaging can be performed accurately and quickly.

[Brief description of drawings]

FIG. 1 is a functional block diagram of an MRI system that realizes a positioning imaging method according to a first embodiment of the present invention.

FIG. 2 is a schematic flowchart showing an example of an inspection procedure including positioning.

FIG. 3 is a schematic flowchart showing an example of the procedure from positioning to actual shooting through a shooting plan (attribute specification).

FIG. 4 is an explanatory diagram illustrating a slice plane of a parent image at the time of photographing a head.

FIG. 5 is an explanatory diagram illustrating a slice plane of a parent image when abdominal imaging is performed.

FIG. 6 is an explanatory diagram illustrating a relationship between attribute designations on parent images (a) and (b) and child images (c) regarding head imaging.

FIG. 7 is an explanatory diagram illustrating a relationship between attribute designations on parent images (a) and (b) and child images (c) regarding abdominal imaging.

FIG. 8 is an explanatory diagram showing a relationship between a parent image and a specifiable attribute.

9 (a) and 9 (b) are explanatory views for explaining the necessity of the saturation method according to the second embodiment of the present invention.

FIG. 10 is a schematic flowchart showing an example of a procedure from positioning to actual photographing in the second embodiment.

FIG. 11 is an explanatory diagram illustrating a relationship between attribute designation on the parent images (a) and (b) and child image (c) regarding cervical spine imaging in the second embodiment.

FIG. 12 is an explanatory diagram showing an example of a combination of a plurality of saturation regions.

FIG. 13 is an explanatory view for explaining the principle of the positioning photographing method in the third embodiment of the present invention.

FIG. 14 is a schematic flowchart showing an example of a procedure from positioning to actual photographing in the third embodiment.

FIG. 15 is an explanatory diagram illustrating the relationship between attribute designation on the parent image (a) and child image (b) relating to abdominal imaging in the third embodiment.

FIG. 16 is an explanatory diagram of a parent image (a) and a child image (b) for explaining a conventional CROSS plan (at the time of head imaging).

FIG. 17 is an explanatory diagram of a preparation image (a), a parent image (b), and a child image (c) for explaining a conventional improved CROSS plan (at the time of head imaging).

FIG. 18 is an explanatory diagram of a parent image (a) and a child image (b) for explaining a conventional CROSS plan (at the time of abdominal imaging).

FIG. 19 is an explanatory diagram of a preparation image (a), a parent image (b), and a child image (c) for explaining a conventional improved CROSS plan (at the time of abdominal imaging).

FIG. 20 is an explanatory diagram of a parent image (a) and a child image (b) for explaining a conventional SAME plan (at the time of head imaging).

FIG. 21 is an explanatory diagram showing a relationship between a conventional SAME plan and a lesion part.

[Explanation of symbols]

4 gradient coil 5 drive circuit 6 Gradient magnetic field controller 7 Control device 8a, 8b transmitter and receiver coils 9 transmitter 10 receiver 11 Storage device 12 arithmetic unit 13 Display 14 Input device

Claims (3)

[Claims] 1. A positioning image preparing means for preparing positioning images of two slice planes intersecting with each other according to a desired imaging region of a subject, and two positioning prepared by this positioning image preparing means. Display means for displaying an image for use, and of the two positioning images displayed by this display means, on one of the positioning images, the imaging range in two directions of the read direction, the encode direction, and the slice direction And a shooting range designating means for designating a shooting range in the remaining one of the three directions on the remaining positioning image, and a shooting range in the lead direction and the encoding direction designated by the shooting range designating means. An MR having a main photographing means for photographing the number of slices having a region corresponding to the number of slices according to the designated photographing range in the slice direction. I device. 2. A positioning image preparing means for preparing positioning images of two slice planes intersecting with each other according to a desired imaging region of a subject, and two positioning prepared by the positioning image preparing means. Displaying means for displaying an image for use, and of the two positioning images displayed by this displaying means, the photographing range in the read direction and the encoding direction can be designated on one of the positioning images, and the remaining positioning is performed. It is possible to specify an imaging range of either the read direction or the encode direction and the slice direction on the use image, and the read direction, the encode direction, and the slice direction on the two positioning images. Shooting range designating means for finally designating a shooting range in the slice direction, and a read direction and an encoding direction designated by the shooting range designating means. An MRI apparatus comprising: a main imaging unit for imaging as many slices each having an area corresponding to the imaging range as described above according to the imaging range in the designated slice direction. 3. A positioning imaging method in magnetic resonance imaging in which an imaging position of a subject is determined by a magnetic resonance imaging apparatus and an image of the imaging position is obtained, said magnetic resonance imaging apparatus comprising: Prepare two positioning images for the intersecting slice planes according to the desired imaging region of the specimen, (ii) display the two positioning images prepared, and (iii) display the two displayed images. Of the positioning images of, the read direction, the encoding direction, and the
And an imaging range in two directions of the slice directions, and an imaging range in the remaining direction of the three directions on the remaining positioning image, and (iv) the specified read direction. And the slice having an area corresponding to the imaging range in the encoding direction is imaged in the number corresponding to the imaging range in the specified slice direction, and the image at the imaging position is obtained. Positioning imaging method in magnetic resonance imaging.