Patent Publication Number: US-2022229127-A1

Title: Image processing apparatus, mri apparatus, and image processing system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority of Japanese Patent Application No. 2021-005334, filed Jan. 15, 2021, the entire contents of which are incorporated herein by reference. 
     FIELD 
     Disclosed Embodiments relate to an image processing apparatus, a magnetic resonance imaging (MRI) apparatus, and an image processing system. 
     BACKGROUND 
     An MRI apparatus is an imaging apparatus which magnetically excites nuclear spin of an object placed in a static magnetic field with a radio frequency (RF) signal having the Larmor frequency and reconstructs an image on the basis of magnetic resonance (MR) signals emitted from the object due to the excitation. An MRI apparatus can acquire MR signals from an object non-invasively. 
     In a system including an MRI apparatus and an optical camera, there is a technique for utilizing an image acquired by the optical camera. This system can display a setting image of an RF coil placed on or near the surface of the object and an image that shows setting support information including the position of a virtual magnetic field center. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the accompanying drawings: 
         FIG. 1  is a block diagram illustrating an overall configuration of an image processing system according to one embodiment; 
         FIG. 2  is a block diagram illustrating functions of the image processing system; 
         FIG. 3A  is a schematic diagram illustrating one example of arrangement information of coil elements of an RF coil; 
         FIG. 3B  is a schematic diagram illustrating another example of the arrangement information of the coil elements of the RF coil; 
         FIG. 4  is a schematic diagram illustrating appearance of the coil elements of the RF coil that is used by being wrapped around an object; 
         FIG. 5  is a schematic diagram illustrating a configuration of an RF coil; 
         FIG. 6A  is a schematic diagram illustrating the first method of associating position information of the RF coil  20  with the coil port to which the RF coil  20  is connected; 
         FIG. 6B  is a schematic diagram illustrating the second method of associating position information of the RF coil  20  with the coil port to which the RF coil  20  is connected; 
         FIG. 6C  is a schematic diagram illustrating the third method of associating position information of the RF coil  20  with the coil port to which the RF coil  20  is connected; 
         FIG. 7  is a schematic diagram illustrating a checking image to be used for determining whether the connection relationship between respective RF coils and the coil ports is correct or not; 
         FIG. 8  is a flowchart illustrating a procedure for determining coil elements to be used in MR imaging on the basis of an optical image generated by an optical camera when the optical image depicts a plurality of RF coils; 
         FIG. 9  is a schematic diagram illustrating coil elements that are to be used at the time of MR imaging and are determined by the procedure shown in  FIG. 8 ; 
         FIG. 10  is a schematic diagram illustrating the first method of associating respective signals of a plurality of wireless RF coils with each RF coil depicted in an optical image; 
         FIG. 11  is a schematic diagram illustrating the second method of associating respective signals of the plurality of wireless RF coils with each RF coil depicted in the optical image; 
         FIG. 12  is a schematic diagram illustrating the third method of associating respective signals of the plurality of wireless RF coils with each RF coil depicted in the optical image; 
         FIG. 13A  is a schematic diagram illustrating a spine coil disposed on a table of a bed; and 
         FIG. 13B  is a schematic diagram illustrating an object placed on the table on which the spine coil is disposed. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinbelow, embodiments of an image processing apparatus, an MRI apparatus, and an image processing system will be described in detail by referring to the accompanying drawings. 
     In one embodiment, an image processing apparatus includes processing circuitry. The processing circuitry acquires an image in which a coil is depicted. Additionally, the processing circuitry acquires information on disposition of the coil and information on a port to which the coil is connected from the image. 
       FIG. 1  is a block diagram illustrating an overall configuration of an image processing system S according to the present embodiment. The image processing system S according to the present embodiment includes an MRI apparatus  1  and an optical camera  8 . The MRI apparatus  1  includes components such as a gantry  100 , a control cabinet  300 , an image processing apparatus (for example, console)  400 , and a bed  500 . 
     The gantry  100  and the bed  500  are disposed in a shield room, in general. The control cabinet  300  is disposed in a machine room, for example, and the console  400  is disposed in an operation room. 
     The gantry  100  includes, for example, a static magnetic field magnet  10 , a gradient coil assembly  11 , a WB (Whole Body) coil  12 , and these components are included in a cylindrical housing. The bed  500  includes a bed body  50  and a table  51 . Additionally, The MRI apparatus  1  further includes an RF coil  20  that is attached near an object. Although a description will be given of the case where the RF coil  20  is one of the components of the MRI apparatus  1  in the following, the RF coil  20  may not be included in the configuration of the MRI apparatus  1 . In this case, though the RF coil  20  is not included in the configuration of the MRI apparatus  1 , the RF coil  20  and the MRI apparatus  1  are configured to be connectable to each other. More specifically, the RF coil  20  and the table  51  of the MRI apparatus  1  are configured to be connectable to each other. 
     The control cabinet  300  includes gradient coil power supplies  31  (to be exact,  31   x  for the X-axis,  31   y  for the Y-axis, and  31   z  for the Z-axis), an RF receiver  32 , an RF transmitter  33 , a sequence controller  34 , and a coil selection circuit  36 . 
     The static magnetic field magnet  10  of the gantry  100  is substantially in the form of a cylinder, and generates a static magnetic field inside the bore (i.e., the space inside the cylindrical structure of the static magnetic field magnet  10 ) which is an imaging region of an object (for example, a patient). The static magnetic field magnet  10  includes a superconducting coil inside, and the superconducting coil is cooled down to an extremely low temperature by liquid helium. 
     The static magnetic field magnet  10  generates a static magnetic field by supplying the superconducting coil with electric current provided from a static magnetic field power supply (not shown) in an excitation mode. Afterward, the static magnetic field magnet  10  shifts to a permanent current mode, and the static magnetic field power supply is separated. Once it enters the permanent current mode, the static magnetic field magnet  10  continues to generate a strong static magnetic field for a long time, for example, over one year. Note that the static magnetic field magnet  10  may be configured as a permanent magnet. 
     The gradient coil assembly  11  is also substantially in the form of a cylinder, and is fixed to the inside of the static magnetic field magnet  10 . The gradient coil assembly  11  is composed of three gradient coils for the X-axis, Y-axis, and Z-axis. Those three gradient coils are supplied with electric currents from the respective gradient coil power supplies  31   x ,  31   y , and  31   z  so as to generate gradient magnetic fields in the X-axis, Y-axis, and Z-axis directions, and the generate gradient magnetic fields are applied to the object. 
     The bed body  50  of the bed  500  can move the table  51  in the upward and downward directions, and moves the table  51  with the object loaded thereon to a predetermined height before imaging. Afterward, at the time of imaging, the bed body  50  moves the table  51  in the horizontal direction so as to move the object inside the bore. 
     The WB body coil is shaped substantially in the form of a cylinder so as to surround an object, and is fixed to the inside of the gradient coil assembly  11 . The WB coil  12  applies an RF pulse transmitted from the RF transmitter  33  to the object, and receives MR signals emitted from the object due to excitation of hydrogen nuclei. 
     The RF coil  20  receives MR signals emitted from the object at a position close to the object. The RF coil  20  according to the present embodiment includes a plurality of coil elements EL. There are various models for the RF coil  20  such as a head coil, a chest coil, a spine coil, a lower-limb coil, and a whole-body coil depending on an anatomical imaging part of the object. Further, a plurality of RF coils  20  can be attached to the object at the same time.  FIG. 1  illustrates a case in which an RF coil  20  for the chest (hereinafter, referred to as a “chest coil”) is attached. 
     The RF transmitter  33  transmits RF pulses to the WB coil  12  on the basis of commands inputted from the sequence controller  34 . The coil selection circuit  36  selects the MR signals received by the WB coil  12  and/or the MR signals received by the RF coil  20 , and transmits the MR signals to the RF receiver  32 . The RF receiver  32  receives MR signals received by the WB coil  12  and/or the RF coil  20 , and transmits raw data obtained by digitizing the received MR signals to the sequence controller  34 . 
     The sequence controller  34  performs a scan of the object by driving the gradient coil power supplies  31 , the RF transmitter  33 , and the RF receiver  32  under the control of the console  400 . When the sequence controller  34  receives the raw data from the RF receiver  32  by performing a scan, the sequence controller  34  transmits the received raw data to the console  400 . 
     The sequence controller  34  includes processing circuitry (not shown), which is configured as hardware such as a processor configured to execute predetermined programs, a field programmable gate array (FPGA), and an application specific integrated circuit (ASIC). 
     The console  400  is configured as a computer including processing circuitry  40 , a memory  41 , a display  42 , and an input interface  43 . The console  400  is one of the aspects of an image processing apparatus. 
     The memory  41  is a recording medium including a read-only memory (ROM) and a random access memory (RAM) in addition to an external memory device such as a hard disk drive (HDD) and an optical disc device. The memory  41  stores various programs to be executed by a processor of the processing circuitry  40  in addition to various data and information. For example, the memory  41  stores a database of various RF coils. In this database, an optical image of each RF coil and the arrangement information of a plurality of coil elements included in this RF coil are associated with each other. 
     The display  42  is a display device such as a liquid crystal display panel, a plasma display panel, and an organic EL panel. The input interface  43  includes various devices for an operator to input various data and information, and is configured of, for example, a mouse, a keyboard, a trackball, and/or a touch panel. 
     The processing circuitry  40  is, for example, a circuit provided with a CPU and/or a special-purpose or general-purpose processor. The processor implements various functions described below by executing programs stored in the memory  41 . The processing circuitry  40  may be configured of hardware such as an FPGA and an ASIC. The various functions described below can also be implemented by such hardware. Additionally, the processing circuitry  40  can implement the various functions by combining hardware processing and software processing based on its processor and programs. 
     The console  400  controls the entirety of the MRI apparatus  1  by working these components. The processing circuitry  40  causes the sequence controller  34  to perform a scan on the basis of inputted imaging conditions, and reconstructs images on the basis of the raw data (i.e., digitized MR signals) inputted from the sequence controller  34 . The reconstructed images are displayed on the display  42  and stored in the memory  41 . 
     The optical camera  8  is installed, for example, on the ceiling of the imaging room where the MRI apparatus  1  is installed. The optical camera  8  includes components such as a lens, an image sensor, an amplifier, and an A/D (Analog to Digital) converter (not shown). The lens is an optical element for refracting and focusing light. The image sensor images the RF coil  20  as an imaging target via an objective optical system (not shown). The amplifier amplifies an output video signal from the image sensor. The A/D converter converts the analog video signal outputted from the amplifier into a digital signal. The optical camera  8  is connected to the processing circuitry  40 , and outputs the acquired image as a digital signal to the processing circuitry  40 . 
     The optical camera  8  images all or part of the table  51  before entering the gantry  100  from above, and acquires an image of the RF coil  20  that is attached to the object placed on the table  51 . For example, the optical camera  8  can acquire a moving image of the RF coil  20  obtained by time-sequentially imaging all or part of the table  51  at a predetermined frame rate. 
     The lens of the optical camera  8  may be a standard lens or a so-called wide-angle lens having a wider angle of view than the standard lens. Disposition of the optical camera  8  is not limited to being installed on the ceiling. The optical camera  8  may be fixed to, for example, a cover (including the inside of the bore) covering the gantry  100  or the end of the gantry  100 . The optical camera  8  may also be attached to the gantry  100  or the wall near the gantry  100 . 
       FIG. 2  is a block diagram illustrating the functions of the image processing system S. 
     As shown in  FIG. 2 , the processing circuitry  40  reads out and executes the computer programs stored in the memory  41  or directly incorporated in the processing circuitry  40  so as to implement a first acquisition function F 1 , a second acquisition function F 2 , a checking function F 3 , a determination function F 4 , and an imaging function F 5 . Although a description will be given of a case where the functions F 1  to F 5  function as software by executing the computer programs in the following, all or some of the functions F 1  to F 5  may be implemented by a circuit such as an ASIC. Further, the functions F 1  to F 4  may be provided in another computer other than the console  400  having the imaging function F 5 , for example, may be provided in a tablet computer. 
     The first acquisition function F 1  includes a function of time-sequentially acquiring optical images, each of which depicts the RF coil  20  attached to the object (for example, the chest coil attached to the object placed on the table  51 ), by using the optical camera  8 . 
     The second acquisition function F 2  includes a function of acquiring both of information on the disposition of the RF coil  20  and information on the port to which the RF coil  20  is connected, and both are acquired from the optical image acquired by the first acquisition function F 1 . The information on the disposition of the RF coil  20  includes the position of the RF coil  20  with respect to the table  51  and the orientation of the RF coil with respect to the table  51 . 
     The checking function F 3  includes a function of asking a user whether the port information on which is acquired as the connection destination of each of the plurality of RF coils by the second acquisition function F 2  is the correct port or not, via an image indicating such a question or via voice indicating such a question immediately before the table  51  with the object placed thereon begins to move to the magnetic field center. 
     The determination function F 4  includes a determination function of determining the coil element(s) to be used for MR imaging from among the plurality of coil elements  20 EL of the RF coil  20  connected to the port information on which is acquired by the second acquisition function F 2 , and this determination function is achieved on the basis of the position of the RF coil  20  with respect to the table  51 , the orientation of the RF coil  20  with respect to the table  51 , and the positional relationship between the magnetic field center and the table  51 . 
     The imaging function F 5  includes: a function of setting the imaging range (Field of View, hereinafter referred to as FOV) and the positional relationship between the magnetic field center and the table  51  on the basis of the imaging conditions; and a function of moving the table  51  with the object placed thereon to the magnetic field center to achieve the positional relationship having been set and then performing MR imaging. 
       FIG. 3A  and  FIG. 3B  are schematic diagrams illustrating one case and another case of how to hold arrangement information of coil elements  20 EL of the RF coil  20 . Each of  FIG. 3A  and  FIG. 3B  illustrates a case where the RF coil  20  has 24 coil elements  20 EL. 
     On the basis of the optical image generated by the optical camera  8 , the processing circuitry  40  of the console  400  according to the present embodiment recognizes at which position of the table  51  the respective coil elements  20 EL are arranged, and then selects the appropriate coil element(s)  20 EL in accordance with the imaging position of MR imaging. 
     Thus, the processing circuitry  40  not only detects the RF coil  20  from the optical image generated by the optical camera  8  but also recognizes the arrangement positions of the respective coil elements  20 EL on the basis of the optical image. Preferably, the memory  41  stores a database in which the optical image of each of the various RF coils  20  is associated with the arrangement information of the plurality of the coil elements  20 EL included in each RF coil  20  such that the arrangement information of the coil element  20 EL can be obtained from the imaged RF coil  20  obtained by the optical camera  8  ( FIG. 3A  and  FIG. 3B ). 
       FIG. 4  is a schematic diagram illustrating appearance of the coil elements  20 EL of the RF coil  20  that is used by being wrapped around the object. 
     Of the RF coils  20 , the body coil and the flex coil are used by being wrapped around the body of the object. Thus, the coil elements EL arranged in the radial direction is deformed. Hence, it is difficult to predict the position of each coil element EL only from the appearance of the RF coil  20 . 
     Assuming that the RF coil  20  wrapped around the object has a cylindrical shape in normal MR imaging, selection of the coil elements  20 EL to be used for MR imaging is segmented in the axial direction. Thus, it is important to correctly deploy the coil element group, which is disposed in the axial direction of the RF coil  20  and has not changed in shape, and to be able to identify the position of the axial coil element group in the table  51  ( FIG. 4 ). 
     Hence, for the convenience of segmentation in the axial direction, it is better to classify the respective coil elements  20 EL by two-dimensional coordinates as shown in FIG.  3 A rather than assigning an individual ID number to each coil element  20 EL and classifying each coil element  20 EL as  20 EL( 1 ),  20 EL( 2 ), . . . ,  20 EL( 24 ) as shown in  FIG. 3B . 
     In the following description, as shown in  FIG. 3A , the coil elements  20 EL are classified by two-dimensional coordinates, and each coil element  20 EL is represented by  20 EL (“row number” “column number”) such as  20 EL( 1 A),  20 EL( 1 B), . . . ,  20 EL( 4 E), and  20 EL( 4 F) by using the row number and column number to which the coil element  20 EL belongs. 
       FIG. 5  is a schematic diagram illustrating a configuration of the RF coil  20 . 
     In general, many RF coils  20  have a line-symmetrical shape such as a rectangle and a cylinder. Thus, the second acquisition function F 2  of the processing circuitry  40  according to the present embodiment recognizes the orientation of the RF coil  20  on the basis of the feature point that indicates a structurally asymmetrical part of the RF coil  20 . 
     For example, when the RF coil  20  is a wired coil, the RF coil  20  has a cable  21  for being connected to the system as shown in  FIG. 5 . In this case, the second acquisition function F 2  can acquire information on the orientation of the RF coil  20  by using the outlet  22  of the cable  21  as the feature point. Further, the second acquisition function F 2  may acquire information on the orientation of the RF coil  20  on the basis of the label  23  and/or the mark attached to the RF coil  20  and another characteristic shape portion of the RF coil  20 . 
     When the RF coil  20  is bent further tightly and the model name or coil type of the RF coil  20  cannot be identified from the optical image, the second acquisition function F 2  may obtain positions of the respective coil elements  20 EL by using coil type that can be determined by the coil type information outputted from the RF coil  20  when the RF coil  20  is connected to the system. 
     When a plurality of RF coils  20  are included in the optical image, it is desirable to associate the position information on each RF coil  20  with the information as to which coil port of the table  51  each RF coil  20  is connected to. 
     Hereinafter, a description will be given of three methods of associating the position information of the RF coil  20  with the coil port to which the RF coil  20  is connected. 
       FIG. 6A ,  FIG. 6B , and  FIG. 6C  are schematic diagrams for illustrating the first, second, and third methods of associating position information of the RF coil  20  with the coil port to which the RF coil  20  is connected, respectively. Each of  FIG. 6A ,  FIG. 6B , and  FIG. 6C  illustrates a case where the optical image depicts two RF coils  20  including a first coil  201  and a second coil  202  and the table  51  has four coil ports including a first port  61 , a second port  62 , a third port  63 , and a fourth port  64 . 
     The first method is a method of detecting the routing (or wiring pattern) of the cable  21 . In the first method, the first acquisition function F 1  acquires an optical image that depicts the first coil  201  connected to the second port  62  via the cable  211  and the second coil  202  connected to the fourth port  64  via the cable  212  ( FIG. 6A ). For each of the first coil  201  and the second coil  202 , the second acquisition function F 2  can acquire the information of the coil port to which each coil is connected from the image acquired by the first acquisition function F 1  on the basis of the respective positions of the cables  211  and  212  so as to associate each coil ( 201 ,  202 ) with the corresponding coil port. 
     The second method is a method of using the optical image for detecting the positions of both hands of the user such as a medical imaging technologist at the time of cable connection. At the time of connecting the cable  21  of the RF coil  20  to the coil port, the user generally connects the cable  21  to the coil port with the one hand while supporting the RF coil  20  with the other hand to prevent the RF coil  20  from being misaligned ( FIG. 6B ). 
     Accordingly, in response to conduction of electrical signals between each of the first and second coils ( 201 ,  202 ) and the system when the cable  21  is connected to the coil port, the first acquisition function F 1  may acquire respective optical images of the first coil  201  and the second coil  202  when each of the first coil  201  and the second coil  202  is connected to the coil port via the cable ( 211 ,  212 ). In this case, on the basis of the positions of both hands of the user depicted in the optical images, the first acquisition function F 1  associates each coil with the coil port by acquiring information on the coil port to which each coil is connected. 
     The third method is a method of associating an RF coil  20  with the coil port closest to this RF coil  20 . When the coil port cannot be associated with each coil by the first method or the second method, the coil port closest to each RF coil may be acquired as the port to which this RF coil is connected so that each RF coil is associated with the acquired coil port ( FIG. 6C ). 
     Of these first to third methods, accuracy of association between each RF coil and the coil port is highest in the first method, followed by the second method, and lowest in the third method. The analysis capability required for the image processing software is highest in the first method, followed by the second method, and lowest in the third method. 
     Accordingly, for example, when the analysis capability of the image processing software is insufficient for implementing the first method, the second method or the third method may be used. The second method and the third method include the possibility of erroneous detection. Thus, when the second method or the third method is used, the information of the coil port to which each coil is connected may be reacquired immediately before the table  51  is moved to the magnetic field center after completion of coil setting in addition to acquiring the same information at the timing when the cable  21  is connected to the coil port. 
       FIG. 7  is a schematic diagram illustrating a checking image to be used for determining whether the connection relationship between the respective RF coils and the coil ports is correct or not. 
     The checking function F 3  may ask the user whether the connection relationship between the respective RF coils and the coil ports acquired by the second acquisition function F 2  is correct or not, immediately before movement of the table  51  to the magnetic field center. Specifically, the checking function F 3  may generate a checking image as to whether the connection relationship between the respective RF coils and the coil ports is correct or not so as to display the checking image on the display  42  or on a monitor provided in the gantry  100 , for example ( FIG. 7 ). Additionally, the checking function F 3  may cause a speaker (not shown) to output checking voice as to whether the connection relationship between the respective RF coils and the coil ports is correct or not. 
       FIG. 8  is a flowchart illustrating a procedure for determining coil elements to be used in MR imaging on the basis of the optical image generated by the optical camera  8  when the optical image depicts a plurality of RF coils  20 . 
       FIG. 9  is a schematic diagram illustrating the coil elements  20 EL that are to be used at the time of MR imaging and are determined by the procedure shown in  FIG. 8 . 
     First, in the step ST 11 , the object is placed on the table  51  of the bed  500 . In the step ST 11 , the object is placed on the table  51  that is lowered in the vertical position, and then, the height of the table  51  is adjusted by raising the table  51  on which the object is placed. The detection of the RF coil  20  may be started in response to the detection that the object is placed on the table  51  on the basis of the camera image. After that, on the basis of the optical images to be time-sequentially acquired, the second acquisition function F 2  may continue to detect the position and orientation of the RF coils  20  on the table  51  and the coil port to which each coil is connected. In this case, the detection frequency may be determined on the basis of the calculation amount of the image processing software and the processing capacity of the system. 
     In the next step ST 12 , two RF coils  20  including the first coil  201  and the second coil  202  are attached to the object placed on the table  51 . 
     In the next step ST 13 , the cable  211  of the first coil  201  is connected to, for example, the second port  62 . The approximate position and orientation of the RF coil  20  (i.e., first coil  201  in this case) as well as its connection destination, i.e., the coil port, may be provisionally determined when its cable  21  is connected to the coil port. 
     In this case, in the step ST 14 , in response to detection that the cable  21  of the RF coil  20  is connected to the coil port, the first acquisition function F 1  acquires an optical image that depicts a plurality of coils and is generated at the moment of the connection. 
     In the step ST 15 , the second acquisition function F 2  provisionally determines the position, orientation, and a port to which each RF coil  20  is connected (connection destination port for (connected port of) each RF coil  20 ). Specifically, the second acquisition function F 2  acquires the disposition (i.e., position and orientation) of each RF coil  20  with respect to the table  51 , uses at least one of the above-described first to third methods for acquiring information on the coil port to which each RF coil  20  is connected, and then associates the position information of each RF coil  20  with the coil port to which each RF coil  20  is connected. When the second method is used, the processing of the steps ST 13  to ST 15  is repeated every time one RF coil  20  is connected to the coil port. 
     In the next step ST 16 , each RF coil  20  and the object are fixed to the table  51  by using, for example, a band. When each RF coil  20  and the object are fixed to the table  51 , it is estimated that the final position and orientation of each RF coil  20  have been determined. 
     In the next step ST 17  subsequent to fixation of each RF coil  20  and the object to the table  51 , the first acquisition function F 1  acquires an optical image immediately before the position of the table  51  corresponding to the target imaging position of the object is moved to the magnetic field center. 
     In the next step ST 18 , the second acquisition function F 2  performs main determination on the position, orientation, and connection destination port for each RF coil  20 . Specifically, the second acquisition function F 2  acquires the disposition (i.e., position and orientation) of each RF coil  20  with respect to the table  51 . Further, the second acquisition function F 2  uses at least one of the above-described firs to third methods for acquiring the information of the coil port to which each RF coil  20  is connected so as to associate the position information of each RF coil  20  with the coil port to which each RF coil  20  is connected. 
     Although the provisional determination in the steps ST 14  and ST 15  and the main determination in the steps ST 17  and ST 18  may be executed in combination as shown in  FIG. 8 , it is sufficient if one of the provisional determination and the main determination is executed, i.e., the other of both may be omitted. In the case of executing the provisional determination in the steps ST 14  and ST 15 , the second method shown in  FIG. 6B  can be used. In the case of executing the main determination in the steps ST 17  and ST 18 , the latest position and orientation of the RF coil  20  can be detected. 
     In the next step ST 19 , immediately before the table  51  is moved to the magnetic field center, the checking function F 3  asks the user whether the connection relationship between each RF coil  20  and the coil port acquired by the second acquisition function F 2  is correct or not ( FIG. 7 ). Since the connection relationship is checked by the user, adverse effects due to erroneous detection of the connection destination port can be prevented. Note that the step ST 19  may be omitted. Execution of the processing of the steps ST 11  to ST 19  provides the position of each RF coil  20  with respect to the table  51 , the orientation of each RF coil  20  with respect to the table  51 , and the connection destination port of each RF coil  20  as shown on the left side of  FIG. 9 . Since the orientation of each RF coil  20  with respect to the table  51  is acquired, the respective positions of the coil elements  20 EL with respect to the table  51  are also determined. 
     In the step ST 20 , on the basis of the position, orientation, and connection destination port of each RF coil  20 , the second acquisition function F 2  determines correspondence relationship between the coil ports and the arrangement of the coil elements  20 EL of each RF coil  20  with respect to the position of the table  51  as shown in the middle of  FIG. 9 . Although the position of each RF coil  20  on the table  51  can be determined from the optical image, the electric signal of each coil element  20 EL is determined by the coil port to which each RF coil  20  ( 201 ,  202 ) is connected. Thus, the result of associating each RF coil  20  with the connection destination port is also added to the arrangement information of the coil elements  20 EL. 
     In the next step ST 21 , the imaging function F 5  acquires the FOV on the basis of the imaging conditions. 
     In the next step ST 22 , the imaging function F 5  sets the positional relationship between the magnetic field center and the table  51  on the basis of the imaging conditions. Specifically, the imaging function F 5  sets the coordinate of the table  51  in the longitudinal direction, which is expected to be positioned at the magnetic field center in MR imaging, on the basis of the imaging conditions. 
     In the next step ST 23 , the determination function F 4  determines the coil elements included in FOV as the coil elements to be used for MR imaging on the basis of: the position of each RF coil  20  with respect to the table  51 ; the orientation of each RF coil  20  with respect to the table  51 ; the coordinate of the table  51  in the longitudinal direction, which is expected to be positioned at the magnetic field center in MR imaging; and the FOV, as shown on the right side of  FIG. 9 . 
     In the next step ST 24 , the imaging function F 5  causes the bed  500  to move the table  51  with the object placed thereon toward the inner side of the bore in such a manner that the coordinate of the table  51  in the longitudinal axis, which is expected to be positioned at the magnetic field center, actually matches the magnetic field center. 
     In the next step ST 25 , the imaging function F 5  causes the respective components such as the sequence controller  34  and the gradient coil power supplies  31  to perform MR imaging. Even when a plurality of RF coils  20  are included in the optical image, the above-described procedure enables appropriate determination of the coil elements to be used in MR imaging on the basis of the optical image generated by the optical camera  8 . 
     According to the processing circuitry  40  of the present embodiment, even when a plurality of RF coils  20  are included in the optical image, the coil element to be used in MR imaging can be determined readily, quickly, and accurately on the basis of the optical image generated by the optical camera  8 . Thus, the examination time can be significantly shortened as compared with the method that requires separate MR imaging for determining the coil elements to be used in MR imaging. 
     Further, the processing circuitry  40  according to the present embodiment is also suitable for sequentially performing imaging sequences at a plurality of imaging positions, as exemplified by whole-body imaging. In some cases, MR imaging is performed on each of FOVs corresponding to the respective imaging positions by alternately repeating movement of the table  51  and MR imaging at the current table position in such a manner that each of the imaging positions is positioned at the magnetic field center in sequence, as exemplified by whole-body imaging. Even in such sequential imaging, the arrangement of the coil element  20 EL of each RF coil  20  is associated with the position of the table  51  as shown in the middle part of  FIG. 9 . Thus, even in such sequential imaging, each time the positional relationship between the magnetic field center and the table  51  changes, on the basis of the updated positional relationship after the change and the FOV corresponding to the updated positional relationship after the change, the determination function F 4  can readily and accurately determine the coil element(s) included in the FOV as the coil element(s) to be used for MR imaging. 
     In the above-described embodiment, a description has been given of the case where each RF coil  20  is a wired coil that transmits an RF signal to the RF receiver  32  via the cable  21 . When the RF coil  20  is a wireless coil that transmits an RF signal to the RF receiver  32  by wireless communication, the cable  21  and the coil port cannot be used. 
     When imaging is performed by using a plurality of wireless RF coils, it is desirable to associate each RF coil, which is included in the optical image and is identified in terms of position and orientation on the table  51 , with the RF coil that wirelessly transmits the output signal to the system. 
     In this case, the second acquisition function F 2  causes each of the plurality of wireless RF coils to sequentially output a signal wirelessly, and acquires the outputted signal. This signal does not have to be an RF signal. The second acquisition function F 2  associates each of the plurality of wireless RF coils that sequentially output signals with each RF coil that is included in the optical image and is identified in terms of position and orientation on the table  51 . For example, the second acquisition function F 2  causes a wireless RF coil  201   w  and another wireless RF coil  202 W to alternately output a signal such that the wireless RF coil  201   w  outputs the signal at odd-numbered timings and the wireless RF coil  202   w  outputs the signal at even-numbered timings. In this case, the second acquisition function F 2  associates the wireless RF coil  201   w  outputting the signal at odd-numbered timings with the head side on the optical image, and associates the wireless coil  202   w  outputting the signal at even-numbered timings with the foot side coil on the optical image, for example. 
     Hereinafter, a description will be given of three methods of associating the signals outputted from each of the plurality of wireless RF coils with each RF coil recognized from the optical image. 
       FIG. 10 ,  FIG. 11 , and  FIG. 12  are schematic diagrams illustrating the first, second, and third methods of associating respective signals of a plurality of wireless RF coils with each RF coil depicted in an optical image, respectively. 
     The first method is a method of using a light emitter such as an LED provided on the surface of each of the plurality of wireless RF coils. In the first method, the first wireless RF coil  201   w  includes a light emitter  241  disposed on its surface, and the second wireless RF coil  202   w  includes a light emitter  242  disposed on its surface. The second acquisition function F 2  may cause each of the wireless RF coils ( 201 W,  202 W) to wirelessly output a signal in sequence and emit light from its light emitter in synchronization with the signal output so as to acquire the outputted signal ( FIG. 10 ). In this case, the second acquisition function F 2  may associate the wireless RF coil outputting the signal acquired at a predetermined timing with the wireless RF coil, light emitter of which emits light in the optical image generated at the predetermined timing. 
     The second method is a method of installing a wireless coil and a wireless access point AP for wireless communication of the RF receiver  32  inside or near the optical camera  8 . In the second method, the second acquisition function F 2  causes each of the plurality of wireless RF coils to output a signal in sequence. On the basis of the transfer times t 1  and t 2  required for the wireless access point AP, which is built in or provided near the optical camera configured to generate optical images, to receive this signal, the second acquisition function F 2  associates the coil outputting this signal with one of the plurality of wireless coils depicted in the optical image. 
     In the case shown in  FIG. 11 , the optical camera  8  calculates the distance between the wireless access point AP and the wireless coil  201   w  from the transfer time t 1  required for data communication between the wireless access point AP and the wireless RF coil  201   w , and calculates the distance between the wireless access point AP and the wireless RF coil  202   w  from the transfer time t 2  required for data communication between the wireless access point AP and the wireless RF coil  202   w . The optical camera  8  calculates the position of the wireless RF coil currently in communication with the system on the basis of the acquired distance, and outputs information on the calculated position of the wireless RF coil currently in communication with the system to the acquisition function F 2  of the processing circuitry  40 . 
     The third method is a method in which the optical camera  8  receives a transmission signal from each of the wireless RF coils. In the third method, the second acquisition function F 2  repeatedly causes each of the plurality of wireless RF coils to output a signal in sequence so as to repeat acquisition of the outputted signal while causing the table  51  to move, and associates the respective wireless RF coils having outputted the signal with the plurality of wireless RF coils depicted in the optical image on the basis of change in transfer time required for receiving the signal from each wireless RF coil. 
     In the third method, the optical camera  8  does not need a function of analyzing the data of the transmission signals to be received from the wireless RF coils, and only needs to be able to recognize the timing or clock time when the signal is received. While the table  51  is being moved to the magnetic field center, each wireless RF coil alternately sends data to the optical camera  8  at predetermined time intervals. The optical camera  8  receives the signal of the data and recognizes the current position of the table  51  and the clock time at which the signal is received. The delay time until the optical camera  8  receives the signal changes depending on the position of the table  51 . Thus, on the basis of the change in delay time of the signal received by the optical camera  8 , the processing circuitry  40  can determine the position of the wireless RF coil that is the transmission source of the received signal, as the position on the table  51 . Even when there are a plurality of wireless RF coils, under the condition that each wireless RF coil transfers data in a fixed order, the processing circuitry  40  can identify which wireless RF coil the received signal belongs to. Further, the transmission data (which may be a waveform) may be characterized for each wireless RF coil such that the optical camera  8  uses the signal of the transmission data to identify the wireless RF coil having transmitted this signal. 
       FIG. 13A  is a schematic diagram illustrating a spine coil  20   sp  disposed on the table  51 , and  FIG. 13B  is a schematic diagram illustrating an object placed on the table  51  on which the spine coil  20   sp  is disposed. 
     The RF coil  20  according to the present embodiment may be an RF coil to be disposed between the table  51  and the object, such as the spine coil  20   sp . As shown in  FIG. 13B , once the object is placed on the table  51 , it is difficult to grasp the entirety of such a large or long RF coil in the optical image to be generated by the optical camera  8 . 
     Even before the object is placed on the table  51 , an RF coil such as the spine coil  20   sp  once disposed on the table  51  is positionally adjusted by the user in some cases. Thus, it is preferred to acquire the position and orientation of an RF coil such as the spine coil  20   sp  and the connection destination port of the cable  22   sp  by using the optical image that depicts the entire RF coil and is generated immediately before the object is placed on the table  51 . 
     Thus, for example, in the case of using the spine coil  20   sp , the first acquisition function F 1  stars acquiring optical images depicting the spine coil  20   sp  at a predetermined frame rate before the object is placed on the table  51  ( FIG. 13A ), and continues the acquisition of these time-sequential optical images. When the object is placed on the table  51 , the second acquisition function F 2  receives an optical image, which is a frame generated before the placement of the object and is within predetermined frames from the timing of the placement, from the first acquisition function F 1 . On the basis of the optical image received from the first acquisition function F 1 , the second acquisition function F 2  acquires the disposition (i.e., position and orientation) of the spine coil  20   sp  with respect to the table  51  and the port to which the spine coil  20   sp  is connected. On the basis of the position, orientation, and connection destination port of the spine coil  20   sp , the second acquisition function F 2  may associate each coil element  20 EL of the spine coil  20   sp  with the position in the table  51 . 
     According to at least one embodiment described above, the coil element  20 EL to be used in MR imaging can be determined on the basis of the optical image generated by the optical camera  8 . 
     In the above-described embodiments, the term “processor” means, for example, a circuit such as a special-purpose or general-purpose CPU (Central Processing Unit), a special-purpose or general-purpose GPU (Graphics Processing Unit), an ASIC, and a programmable logic device including: an SPLD (Simple Programmable Logic Device); a CPLD (Complex Programmable Logic Device); and an FPGA. When the processor is, for example, a CPU, the processor implements various functions by reading out programs stored in a memory and executing the programs. 
     Additionally, when the processor is, for example, an ASIC, instead of storing the programs in the memory, the functions corresponding to the respective programs are directly incorporated as a logic circuit in the circuit of the processor. In this case, the processor implements various functions by hardware processing in which the programs incorporated in the circuit are read out and executed. Further, the processor can also implement various functions by executing software processing and hardware processing in combination. 
     Although a description has been given of the case where a single processor of the processing circuitry implements each function in the above-described embodiments, the processing circuitry may be configured by combining a plurality of independent processors which implement the respective functions. When a plurality of processors are provided, the memory for storing the programs may be individually provided for each processor or one memory may collectively store the programs corresponding to the functions of all the processors. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. These embodiments can be implemented in various other aspects, and various omissions, substitutions, changes, and combinations of embodiments can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope of the invention and the gist thereof, and are also included in the invention described in the claims and the equivalent scope thereof.