JP2009279218A - Magnetic resonance imaging apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily set an imaging protocol and an imaging slice position which are optimum for an inspection region and a case in an MRI inspection. <P>SOLUTION: When an input such as the inspection region and the case, etc., is received, the control part 111 of an MRI apparatus reads the imaging protocol and recommended imaging slice position which are optimum for the inspection from the library of a storage device 115, and allows a display part 108 to display the protocol and position. Besides, coincidence between the imaging slice position imaged in the past and the imaging slice position being set at present is calculated, so as to determine whether imaging is performed or not with a coincidence threshold as reference, or a difference between the imaging slice position imaged in the past and the imaging slice position being set at present is calculated, so as to perform imaging concerning the imaging slice position being set at present in response to the imaging slice position imaged in the past. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a magnetic resonance imaging (MRI) apparatus, and more particularly to an MRI apparatus capable of automatically presenting an optimal imaging protocol and slice position according to examination contents.

  In examination using MRI, various imaging protocols are used depending on cases. For example, in the cardiac region, imaging such as cine imaging (function / morphological diagnosis), load / rest perfusion (viability diagnosis), delayed contrast imaging (viability diagnosis), black blood imaging (morphological diagnosis), coronary artery imaging (morphological diagnosis), etc. An imaging protocol in which various techniques are combined in accordance with the subject's symptoms and the purpose of diagnosis is created and implemented (Non-Patent Document 1). An imaging protocol (also called an examination protocol) includes an imaging sequence, imaging parameters, and profile information for specifying them, and is an imaging protocol that is optimal for examination according to symptoms and examination contents for each subject. Is very cumbersome and takes time to prepare for inspection.

As a solution, Patent Document 1 proposes a system that searches a pre-registered protocol from an inspection request. However, even if only the protocol is determined, the examination cannot be performed unless the imaging slice can be accurately set at the target site. Since MRI is non-invasive, there are cases where the same part of the same subject is repeatedly imaged for the purpose of post-operative follow-up. In this case, even for the same subject, it is difficult to repeatedly image the same slice plane at intervals, especially when setting a complex double oblique slice plane, such as the cardiac imaging described above. It is very difficult to take an image of the same cross section after a period of time.
CMR Image Acquisition Protocols V1.0, March 2007, SCMR JP 2007-143719 A

  It is an object of the present invention to provide an MRI apparatus capable of presenting an appropriate slice position according to a set protocol as well as an optimal protocol for examination. Accordingly, it is an object of the present invention to provide an MRI apparatus that can obtain an image suitable for an inspection purpose and can easily image the same cross section as a past inspection even when the inspection is separated in time. .

  The MRI apparatus of the present invention that solves the above-described problems is characterized by comprising slice setting means for determining an optimal slice position according to a set imaging protocol, and further, a slice position determined as a past image slice position. Means for determining the degree of coincidence with the position is provided.

  That is, the MRI apparatus of the present invention includes an imaging unit that images a subject by magnetic resonance, a display unit that displays an image captured by the imaging unit, and a control unit that controls the operation of the imaging unit. The means comprises a protocol setting means for setting an imaging protocol, and a slice setting means for determining an optimal slice position based on the imaging protocol set by the protocol setting means, and the imaging protocol and slice setting means set by the protocol setting means The imaging is controlled according to the imaging slice determined by.

  The control means includes storage means for storing an imaging protocol and a recommended slice position for each imaging protocol as a library, and the slice setting means reads the recommended slice position for the set imaging protocol from the storage means. . In the MRI apparatus of the present invention, the control means includes an input means for accepting an input of the examination contents of the subject, and the protocol setting means is stored in the storage means based on the examination contents input via the input means. Among the imaging protocols, at least one imaging protocol optimal for the examination is determined. The imaging protocol set by the protocol setting unit and the imaging slice determined by the slice setting unit are displayed on the display unit.

  Furthermore, the MRI apparatus of the present invention reads from the storage means a storage means for storing the past image information of the subject and the past image of the subject imaged with the same protocol as the imaging protocol determined by the protocol setting means, Comparing means for comparing the slice position in the past image with the slice position determined by the slice setting means is provided.

  The comparison result by the comparison unit is displayed on the display unit, and the user can determine whether the slice position determined by the slice setting unit is appropriate based on the comparison result. Alternatively, the control unit determines whether or not the slice position determined by the slice setting unit is appropriate based on the comparison result by the comparison unit, and executes imaging based on the determination result. The slice setting means adjusts the determined slice position in accordance with the user's judgment or the judgment by the control means.

  In the present invention, when an examination site and a case are designated, a recommended protocol and a slice position, and a relationship between a subject and a slice position are displayed. Therefore, even an inspection that requires complicated setting of a double oblique surface can be easily prepared. In addition, since it is also possible to easily capture images in accordance with past slice positions, the same slice position can be obtained in follow-up observation or the like compared to the conventional method in which it is difficult to image the same slice position after a period of time. If you want to repeat the imaging, you can easily set.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration of a typical MRI apparatus to which the present invention is applied. This MRI apparatus has, as imaging means, a magnet 102 that generates a static magnetic field around the subject 101, a gradient magnetic field coil 103 that generates a gradient magnetic field in the space, and an RF coil 104 that generates a high-frequency magnetic field in this region. An RF probe 105 that detects an MR signal generated by the subject 101 is provided. The subject 101 is usually inserted into the static magnetic field space while lying on the bed 112.

  The gradient magnetic field coil 103 is composed of gradient magnetic field coils in three directions of X, Y, and Z, and each generates a gradient magnetic field in response to a signal from the gradient magnetic field power supply 109. The RF coil 104 generates a high-frequency magnetic field according to the signal from the RF transmitter 110. The signal of the RF probe 105 is detected by the signal detection unit 106, signal processed by the signal processing unit 107, and converted into an image signal by calculation. The image is displayed on the display unit 108.

  The operations of the gradient magnetic field power supply 109, the RF transmission unit 110, and the signal detection unit 106 are controlled by the control unit 111 in accordance with a control time chart called a pulse sequence. In addition to the internal storage devices such as RAM and ROM, the control unit 111 includes an external storage device 115 such as a magnetic disk and an input device 113 such as a mouse and keyboard as shown in FIG. 2A. Various pulse sequences that differ depending on the imaging method are stored as programs in the storage device of the control unit 111. Parameters and inspection details necessary for imaging are input to the control unit 111 via the input device 113. The display unit 108 displays a GUI that is an interface between the control unit 111 and the user.

  In the MRI apparatus according to the present embodiment, the control unit 111 receives an input from the input device 113 and determines an imaging protocol and a slice position according to the examination content. Details of the control unit 111 for realizing these functions are shown in FIG. 2A. As shown in the figure, a protocol setting unit 211, a slice setting unit 212, a slice comparison unit 213, an imaging control unit 214, and a main control unit 215 for controlling these units are provided. Further, the storage device 115 stores data obtained by making a library of imaging protocols recommended for each examination site and case name, and data indicating imaging slice positions (center coordinates and inclinations) for each imaging protocol. In addition, images captured in the past are stored together with information such as the subject name, examination site, case name, and imaging technique.

  FIG. 2B shows an example of data stored in the storage device 115. In this example, the recommended protocol corresponding to the examination site and the case name and the slice position for each protocol are stored in one table.

  When the protocol setting unit 211 receives an examination site, a case name to be examined, and the like from the input device 113, the protocol setting unit 211 reads a recommended imaging protocol from the storage device 115 and displays the recommended imaging protocol on the display unit 108. A command for selecting a protocol is received and passed to the slice setting unit 212 and the imaging control unit 214.

  When the imaging protocol is set by the protocol setting unit 211, the slice setting unit 212 takes out information on the imaging slice position corresponding to the imaging protocol set from the storage device 115, displays the slice plane on the display unit 108, A command for selecting an imaging slice position is received from the input device 113, and the slice position is set. Alternatively, a comparison result from a slice comparison unit 213 described later is received and a slice position is set. Then, the information of the set slice position, that is, the center coordinates and the inclination (oblique) are passed to the imaging control unit 214.

  The slice comparison unit 213 reads a past image of the subject designated from the storage device 115 and information (slice position) associated therewith in response to a command from the input device 113, and reads the read slice position and slice setting unit 212. Are compared with the slice position to be processed, and the result is passed to the slice setting unit 212 and displayed on the display unit.

  The imaging control unit 214 controls imaging so as to activate a predetermined pulse sequence according to the imaging protocol information set by the protocol setting unit 211 and the slice position information set by the slice setting unit 212.

<First Embodiment>
Hereinafter, an embodiment of the operation of the MRI apparatus having the above configuration will be described. In the present embodiment, a case where the examination site is the heart will be described as an example. FIG. 3 shows an operation procedure, and FIGS. 4 and 5 show screens (examples of UI) at each stage.

  First, the user inputs an examination site and a case name (step 301). In response to this input, the protocol setting unit 211 reads the recommended protocol from the library stored in the storage device 115 and displays it on the display unit 108 (step 302).

  FIG. 4 shows an example of a UI screen. On the upper side of the screen, the entered examination region 401 and case name 402 are displayed, respectively, and a recommended protocol 403 is displayed. The recommended protocol displayed is not limited to one and can be selected by the user. When one of the displayed recommended protocols is selected by the user (step 303), the slice setting unit 212 selects an imaging slice plane optimal for the selected recommended protocol from the slice plane information stored in the storage device 115. The data is read and displayed in the lower windows 404 to 406 (steps 304 to 306).

  As a method of displaying the slice plane, there are a method of displaying on a model and a method of displaying on an actually captured image, either of which may be adopted (step 304). When displaying on the model (step 305), as shown in FIG. 4, human body models 411 to 413 and 421 to 423 are drawn in windows 404 to 406 provided corresponding to the imaging section. Specifically, when the short axis of the heart is the imaging cross section, when the four chambers are the imaging cross section, and when the long axis is the imaging cross section, windows are respectively set and displayed in these windows. Examples of the slice plane 400 are shown on the models 411 to 413 and 421 to 423.

  When displaying on the actually captured image, first, the scout image Load buttons 431 to 433 are operated to display the scout image of the subject in the windows 404 to 406 for displaying the slice plane (step 306). The scout image is an image captured in advance with low spatial resolution for positioning the subject prior to the main imaging, and is stored in the storage device of the control unit 111. FIG. 5 shows an example of a screen on which scout images 511 to 513 and 521 to 523 are loaded. In FIG. 5, the same elements as those in FIG. 4 are indicated by the same numbers. In FIGS. 4 and 5, the model displays two images, a COR cross-sectional image and an AX cross-sectional image. However, a three-sectional image including the TRANS cross-sectional image may be displayed, or any one of the three cross-sectional images may be displayed. Two or two may be used.

  When a scout image is displayed in each of the windows 404 to 406, a location 510 desired to be the center of the FOV is designated with a mouse or the like. When the center of the FOV is designated (step 307), the imaging slice plane 500 registered in advance with the designated position as the center of the FOV is displayed (step 308). The scout image may be loaded after the slice plane is displayed on the model (step 309). When the slice plane is displayed in this way, an imaging section is selected, and the displayed imaging slice plane is adjusted as necessary (steps 310 and 311), and imaging is started (steps 312 and 313). Since the scout image is an actual image, it is also possible to execute an imaging protocol that has been set without adjustment and take an image. Steps 303 to 313 are repeated until imaging of all necessary imaging sections is executed.

  According to the present embodiment, when an imaging protocol is set, an optimal slice plane is set for an imaging cross section determined by the imaging protocol. Therefore, the user needs to reset the slice plane every time the imaging protocol is different. Therefore, the imaging can proceed smoothly. In particular, when the setting of the slice plane is displayed on a scout image that is actually captured, the adjustment of the slice plane may be omitted or the minimum adjustment may be performed, and the operability is greatly improved.

<Second Embodiment>
In the present embodiment, the imaging slice plane set in the first embodiment is compared with images captured in the past, and the degree of matching between the imaging slices is evaluated, and whether or not to execute imaging A function to judge has been added. This embodiment is effective when past data is stored for the same subject. FIG. 6 shows an operation procedure of the present embodiment. Hereinafter, the description of the same procedure as in the first embodiment (FIG. 3) will be simplified, and the description will focus on the different procedure.

  First, when the user inputs the examination site and case name, the recommended protocol and imaging section example are displayed. When the protocol is selected and the scout image is loaded, the imaging slice is displayed in the window displaying the scout image. This is the same as the embodiment (steps 301 to 304).

  Next, when an imaging section is selected to adjust the imaging slice (step 600), a scout image and an imaging slice 700 are displayed in the imaging slice position setting windows 711, 712, and 713 as shown in FIG. ing. The previous image load button 740 on this screen (UI) is operated to load an image of a past slice plane for the same imaging section (steps 601 and 602). Past images are displayed in a window 721. When there are a plurality of past slices, any slice can be selected. For example, a plurality of slices may be sequentially displayed in the window 721 and a desired slice may be selected, or a list of past images may be displayed in another window and an arbitrary slice may be selected. Good. Next, the image of the slice plane 700 set on the windows 711 to 713 is displayed on the window 722.

  As an image displayed on the window 722, the following two images can be exemplified. One is an image obtained by executing imaging with the same cardiac time phase and the same spatial resolution as the past image displayed in the window 721. Or in order to shorten imaging time, the state which made the spatial resolution low and the image imaged asynchronously may be sufficient. Such an image is acquired by performing preliminary imaging after the slice plane 200 is set.

  As another image, a scout image is acquired as 3D data and used. When the slice plane 700 is set, a slice plane corresponding to the slice plane 700 is cut out from the 3D scout image and displayed on the window 722.

  Next, ROIs 731 and 732 are set in order to determine the degree of coincidence between past images displayed in the windows 721 and 722 and the image of the current slice plane (step 603). The degree of coincidence between the two images can be determined by comparing the entire images. However, in order to improve the determination accuracy, it is desirable to set the ROI in the imaging target region and determine the degree of coincidence within the ROI. . The degree of coincidence is displayed as a numerical value 741 of 0 to 1, for example, 0 when no coincidence and 1 when coincidence (step 604). With reference to this value, the user starts imaging when it is determined that the images match (steps 605 and 606). The imaging start can be automatically performed instead of a user operation. In this case, a threshold value is set in advance for the degree of coincidence, and imaging is automatically started when the threshold value is exceeded.

  An example of a method for calculating the degree of coincidence of two images will be described with reference to FIG. First, as shown in FIG. 7, ROIs 802 and 812 are set in the imaging target portions (hearts in this example) on the slice planes displayed in the windows 801 and 811. The ROI allows the user to select an arbitrary area with a mouse or the like. When the ROI is set, a signal value profile is acquired along either the x or y direction in the ROI. FIG. 8 shows signal value profiles 804 and 814 acquired for the lines 803 and 813 in the y direction. Next, a correlation coefficient is calculated using the equation (1) between the acquired signal value profiles of both images (step 821).

If the profile is (y ₁ , y ₂ ) = {(y _1i , y _2i )} (i = 1, 2, ..., n, n is the number of lines),

When the correlation coefficient for one line is obtained, the same processing is performed for adjacent lines, and the correlation coefficient is calculated for all lines in the ROI (step 822). When the correlation coefficients for all lines (n lines) are calculated, the average value is obtained (step 823), and the average value is displayed as the image matching degree in the ROI (step 824).

  According to the present embodiment, the degree of coincidence between the set slice plane and the past image to be compared is calculated, so the user can determine whether the set slice plane is appropriate based on the degree of coincidence displayed as a numerical value. It is possible to determine whether or not the slice is appropriate by comparing the calculated degree of coincidence with a preset threshold value, and to perform imaging. As a result, even when examinations are performed for the same subject at intervals, images of the same slice can always be compared, and the quality of diagnosis can be improved. In this embodiment as well, it is only necessary to check the degree of coincidence with a past image as necessary, and it is also possible to perform imaging without checking the degree of coincidence.

<Third Embodiment>
In this embodiment as well, the processing until the slice plane is set is the same as in the first and second embodiments, but the second embodiment is a method for determining the suitability of the slice plane using past images. The form is different. That is, in the second embodiment, the suitability of the set slice plane is determined by correlating the signal values of the past image and the current image, but in this embodiment, the correlation of the signal values is determined. Instead, the suitability of the slice is determined using the information on the position where it can be determined that it is anatomically identical in the past image.

  The procedure of the present embodiment is shown in FIG. First, a past scout image and a scout image (current scout image) used for imaging to be executed are loaded (steps 900 and 910), respectively. The loading of the scout image is started, for example, by operating the scout image load buttons 1053 and 1054 on the screen shown in FIG. Thereby, as shown in FIG. 10, the past scout image and imaging slice 1010 are displayed in windows 1011 to 1013, and the current scout image and recommended imaging slice 1020 are displayed in 1021 to 1023, respectively. The images loaded in the windows 1011 to 1013 can be images other than the MRI stored in the DICOM server or the like, for example, images such as CT. On the slice planes 1010 and 1020, points 1015 and 1025 indicating the respective FOV centers are displayed. Here, the user designates arbitrary locations 1030 and 1040 on the past and current scout images (steps 901 and 911). These two points specify a place that seems to be anatomically the same. For example, the shoulder joint portion is designated in the example of FIG. When designated, as shown in FIG. 11, a vector A connecting the designated point 1030 and the FOV center 1015 and its distance D, and an angle θA formed by the normal vector An and the vector A of the imaging slice 1010 are calculated (step 902-905). That is, the oblique and distance of the imaging slice 1010 with respect to the designated point 1030 are obtained.

Specifically, when the coordinates of the point 1030 are (a _x1 , a _y1 , a _z1 ) and the coordinates of the FOV center 1015 are (a _x2 , a _y2 , a _z2 ), the component of the vector A in FIG. a _x , a _y , a _z ) and the magnitude | A | are expressed by the following equations (2) and (3), respectively.

On the other hand, if the component of the normal vector An of the slice plane 1010 is (a _xn , a _yn , a _zn ), the angle θA formed by the vector A and the normal vector An, that is, the oblique of the imaging slice 1010 with respect to the point 1030 is It is calculated | required by following Formula (4).

Similarly, on the current scout image, the oblique of the imaging slice 1025 with respect to the reference point 1040 from the vector B between the point 1040 and the FOV center 1025 and the normal vector An of the imaging slice 1020 (in the equation (4)) The calculated sin θB) and the distance are obtained (steps 1012 to 1014). If the specified points 1030 and 1040 are anatomically approximate positions, the difference between the oblique sin θA and sin θB thus obtained corresponds to the difference between the slice position 1015 of the past scout image and the slice position 1025 of the current scout image. To do. Therefore, the difference between the slice position 1010 taken in the past and the slice position 1020 taken from now is obtained from the difference between oblique sin θA and sin θB (step 920). Based on this difference, as shown in FIG. 11, an imaging slice position (position indicated by a dotted line in the figure) corresponding to the past imaging slice position is displayed on the window displaying the current scout image (step 921). . When the slice set button 1051 displayed on the screen (UI) in FIG. 10 is operated, the slice setting unit 212 sets a position corresponding to the past imaging slice position displayed in the current scout image as a slice position (step S1). 922). Thereafter, the imaging START button 1052 is operated to perform imaging (step 923).

  According to the present embodiment, as in the second embodiment, images of the same slice can always be compared even when testing is performed for the same subject after a period of time, thereby improving the quality of diagnosis. can do. Compared with the case of calculating the correlation of image signal values, it is possible to compare the past slice plane and the current slice plane with a small amount of calculation.

  As described above, as the second and third embodiments, the operation of the MRI apparatus having the function of comparing the slice plane to be imaged with the past slice plane has been described. However, the present invention is not limited to these embodiments.

The figure which shows the whole structure of the MRI apparatus with which this invention is applied. Block diagram showing details of controller The figure which shows an example of the table memorize | stored in the memory | storage device The flowchart which shows the 1st Embodiment of this invention The figure which shows the example of UI structure of 1st Embodiment The figure which shows the example of UI structure of 1st Embodiment The flowchart which shows the 2nd Embodiment of this invention The figure which shows the example of UI structure of 2nd Embodiment The figure explaining the calculation method of the coincidence degree by 2nd Embodiment The flowchart which shows the 3rd Embodiment of this invention The figure which shows the example of UI structure of 3rd Embodiment The figure explaining the slice adjustment method by 3rd Embodiment

Explanation of symbols

101 ... subject, 102 ... static magnetic field magnet, 103 ... gradient coil, 104 ... RF coil, 105 ... RF probe, 106 ... signal detector, 107 ... signal Processing unit 108 ... Display unit 109 ... Gradient magnetic field power supply 110 ... RF transmitter 111 ... Control unit 112 ... Bed 113 ... Input device 115 ... Storage device 211 ... Protocol setting unit 212 ... Slice setting unit 213 ... Slice comparison unit 214 ... Imaging control unit 215 ... Main control unit

Claims (10)

In a magnetic resonance imaging apparatus comprising: an imaging unit that images a subject by magnetic resonance; a display unit that displays an image captured by the imaging unit; and a control unit that controls the operation of the imaging unit.
The control means includes a protocol setting means for setting an imaging protocol;
Based on the imaging protocol set by the protocol setting means, comprising a slice setting means for determining an optimal slice position,
A magnetic resonance imaging apparatus that controls imaging according to an imaging protocol set by the protocol setting means and an imaging slice determined by the slice setting means. In the magnetic resonance imaging apparatus according to claim 1,
The control means includes storage means for storing an imaging protocol and a recommended slice position for each imaging protocol as a library, and the slice setting means obtains a recommended slice position for the set imaging protocol from the storage means. A magnetic resonance imaging apparatus characterized by reading. The magnetic resonance imaging apparatus according to claim 2.
The control means includes input means for receiving input of examination contents of the subject,
The protocol setting means determines at least one imaging protocol most suitable for examination among imaging protocols stored in the storage means, based on examination contents input via the input means. Magnetic resonance imaging device. The magnetic resonance imaging apparatus according to claim 1.
The magnetic resonance imaging apparatus, wherein the control means causes the display means to display the slice position determined by the slice setting means superimposed on the image or model of the subject. In the magnetic resonance imaging apparatus according to claim 1,
The magnetic resonance imaging apparatus, wherein the control means includes slice adjustment means for adjusting a slice position determined by the slice setting means. In the magnetic resonance imaging apparatus according to claim 1,
The control means includes storage means for storing past image information of the subject;
The past image of the subject imaged with the same protocol as the imaging protocol determined by the protocol setting unit is read from the storage unit, and the slice position in the past image is compared with the slice position determined by the slice setting unit Comparing means to
Slice adjusting means for adjusting the slice position determined by the slice setting means based on the comparison result of the comparing means;
A magnetic resonance imaging apparatus comprising: The magnetic resonance imaging apparatus according to claim 6.
The comparison unit calculates a degree of coincidence between the past image and the image at the slice position determined by the slice setting unit, and / or the past image with respect to the anatomical feature point of the subject. A magnetic resonance imaging apparatus comprising: a calculation means for calculating an oblique at a slice position and an oblique at a determined slice position with respect to an anatomical feature point of the subject, and calculating a difference between the obliques. The magnetic resonance imaging apparatus according to claim 7.
The magnetic resonance imaging apparatus characterized in that the comparison means causes the display means to display a result calculated by the calculation means. The magnetic resonance imaging apparatus according to claim 7.
The magnetic resonance imaging apparatus, wherein the control means includes performing imaging at the determined slice position when a value calculated by the calculation means is within a preset threshold value. A method for determining a slice position in a magnetic resonance imaging apparatus, comprising:
Determining and displaying an optimal slice position according to the set imaging protocol based on the correspondence between the imaging protocol stored in advance and the slice position;
Displaying past slice images captured with the same imaging protocol as the set imaging protocol;
Calculating a degree of coincidence between the determined optimum slice position and a slice position in the past slice image;
Determining a slice position to be imaged based on the calculated degree of coincidence.

Images