Magnetic resonance imaging device and automatic channel selection method for multi-channel receiving coil

Abstract

The invention provides a magnetic resonance imaging device and an automatic channel selection method of a multi-channel receiving coil. The present invention addresses the problem of automatically selecting a channel for receiving a signal from an imaging site with high sensitivity in imaging using a multi-channel reception coil. In the present invention, a camera image of a subject after wearing a receiving coil acquired before the subject is transported to an imaging position, information specifying the position (target position) of an imaging site of the subject, and design information of the receiving coil are compared, and an element of the receiving coil including the target position is selected. A coil region including the selected element and brought into an active state is determined. The determination of the target position is performed by a method that a user specifies on a camera image of a subject before wearing a receiving coil, a user specifies on a pre-scan image, or the like. Image reconstruction is performed using signals received by the elements of the coil region in the active state.

Description

Technical Field

[0001] The present invention relates to a technology for automating channel selection in a magnetic resonance imaging (hereinafter referred to as MRI) apparatus using a multi-channel receiving coil. Background Art

[0002] In an MRI device, although the receiving coil that receives the nuclear magnetic resonance signals from the subject is sometimes also served by an RF transmitting coil for high-frequency magnetic field irradiation fixed to the device, since it can detect the signals from the examination part with high sensitivity, a receiving coil configured with multiple loop coils (surface coils) worn in close contact with the examination part of the subject is widely used.

[0003] There are various types of surface coils that combine multiple coil elements corresponding to the shape of the examination site, such as the head, abdomen, and limbs. The multiple elements are connected to the multiple channels of the receiver, and the image is reconstructed using the nuclear magnetic resonance signals received in the multiple channels. If the number of channels of the receiving coil increases, the image quality will generally improve, so the multi-channelization of the receiving coil is being promoted. In addition, in order to improve the workflow of coil setting, a receiving coil unit with a wide sensitivity range configured with multiple elements has been developed, and the multiple elements can capture multiple parts with a single coil setting.

[0004] Furthermore, in order to obtain good image quality in a workflow including coil setting, it is important to position the examination site where the receiving coil is worn at the center of the magnetic field, and techniques for this purpose have also been proposed (Patent Documents 1 and 2).

[0005] Patent Document 1: Japanese Patent Application Publication No. 2014-128667

[0006] Patent Document 2: Japanese Patent Application Publication No. 2020-141732

[0007] The multi-channel receiving coil capable of capturing images of multiple parts at once is worn on the subject in a manner that covers a wide area (e.g., the chest or abdomen of the subject). However, even when the examination part is a part of tissue or organ included in the chest or abdomen, signals from all channels must be processed, so the image quality of the object part may be degraded due to the mixing of unnecessary signals. In addition, the increase in the number of channels will increase the cost of the receiving system. Therefore, in order to obtain high image quality for a specified examination part, it is necessary to select the necessary channels to generate an image.

[0008] The technology described in Patent Document 1 is a technology that adds multiple marks to the receiving coil, specifies the mark closest to the inspection site, and positions the subject so that the mark position is located at a predetermined position in the magnetic field space, which cannot solve the above-mentioned problem. In addition, the technology described in Patent Document 2 is a technology that accepts the user's designation of the focus position using the camera image and moves the focus area to the center of the magnetic field to obtain a scout image, which is also not a technology that solves the above-mentioned problem.

[0009] Furthermore, when the subject is moved to the imaging space (magnetic field center), a blanket or the like is sometimes placed on the subject wearing the receiving coil from above. In this case, in the above-mentioned prior art, it is difficult to locate the desired marking position or the region of interest specified using the camera image to the magnetic field center. Summary of the invention

[0010] The present invention aims to provide a technology for automatically selecting a coil element or a coil area composed of a plurality of coil elements that is necessary and sufficient for imaging a desired examination part after a receiving coil having a plurality of coil elements (channels) is worn on a subject. The present invention also aims to provide a technology for arranging the automatically selected coil area at the center of a magnetic field, thereby acquiring a good image of the examination part.

[0011] In order to solve the above-mentioned problems, the present invention performs the following processing: checking the camera image of the subject after wearing the receiving coil acquired before the subject is transported to the imaging position, determining the information of the position (target position) of the imaging part of the subject and the design information of the receiving coil, selecting the element of the receiving coil including the target position, and determining the coil area including the selected element and making it activated.

[0012] That is, the MRI device of the present invention comprises: an imaging unit comprising a multi-channel receiver for receiving nuclear magnetic resonance signals generated by a subject; and a control unit for controlling the imaging unit, the control unit comprising: a camera image acquisition unit for acquiring an image from a camera arranged in the MRI device; a target position determination unit for determining the imaging target position of the subject; and a verification unit for verifying the camera image acquired by the camera image acquisition unit and the design information of the receiving coil, and determining the coil elements of the receiving coil covering the target position determined by the target position determination unit.

[0013] The design information of the receiving coil is, for example, CAD data when designing the receiving coil, including information related to the design, such as the arrangement and size of components, the ID of the receiving coil (type, size, etc.), information that can know the relationship between the external appearance and the internal components (marks or characteristic shapes, etc.). Such design information of the receiving coil is stored in the internal memory of the device or in an external storage device according to the types of multiple receiving coils.

[0014] For example, as information that can be known from the outside (i.e., information that can be identified as a camera image), the receiving coil is marked with the ID of the receiving coil (type, size, etc.) or information that can know the relationship with internal components (marks or characteristic shapes, etc.).

[0015] Furthermore, the automatic channel selection method of a multi-channel receiving coil of the present invention is a method for selecting coil elements of a multi-channel receiving coil used in an MRI device, comprising the following steps: acquiring an image from a camera configured in the MRI device; determining a target position in a subject; and verifying a camera image showing a subject wearing a receiving coil including a plurality of coil elements, the target position, and design information of the receiving coil, and determining the coil elements of the receiving coil including the target position.

[0016] Effects of the Invention

[0017] According to the present invention, by comparing the camera image and the target position associated therewith with the design information of the receiving coil, the element of the receiving coil including the target position can be automatically selected. Thus, only the coil area including the target position can be activated to reconstruct an image with good image quality excluding signals from unnecessary elements.

[0018] Furthermore, even if the receiving coil cannot be captured by the camera due to a cover covering the receiving coil after the receiving coil is attached to the subject, the target position can be arranged at the center of the magnetic field. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a diagram showing the overall outline of an MRI apparatus.

[0020] Figure 2 This is a block diagram of the camera unit.

[0021] Figure 3 This is a block diagram of the control unit.

[0022] Figure 4 This is a diagram showing the flow of operations of the channel selection unit.

[0023] Figure 5 This is a diagram for explaining the processing of the first embodiment.

[0024] Figure 6This is a diagram for explaining coil region determination according to Modification 1.

[0025] Figure 7 This is a diagram for explaining target position determination based on Modification Example 2.

[0026] Figure 8 This is a diagram for explaining the processing of implementation mode 2.

[0027] Fig. 9 This is a diagram for explaining the processing of implementation mode 3.

[0028] Fig.10 This is a diagram for explaining target position determination based on Modification Example 3.

[0029] Fig.11 This is a diagram for explaining the arrangement of receiving coils and markers to which the fourth embodiment is applied.

[0030] Fig.12 This is a diagram for explaining the calibration using the interval of marks arranged on the receiving coil or the fixing tape.

[0031] Fig.13 It is a diagram showing a modified example of the fourth embodiment using a fixing tape.

[0032] Fig.14 This is a diagram for explaining a receiving coil to which the fifth embodiment is applied.

[0033] Fig.15 This is a diagram for explaining the processing of implementation mode 5.

[0034] Fig.16 This is a diagram showing the process flow of implementation mode 5.

[0035] Explanation of symbols

[0036] 1-MRI apparatus, 10-gantry, 20-computer, 30-camera, 40-external storage device, 50-display device, 50A-display device, 60-UI unit, 70-subject, 100-imaging unit, 104-receiving coil, 105-bed, 124-fixing belt, 200-control unit, 210-channel selection unit, 211-camera image acquisition unit, 213-target position determination unit, 215-verification unit, 230-display control unit, 240-imaging control unit, 300-camera image, 400-design information of receiving coil, 501-line indicating target position, 502-FOV, 503-coil area, 600-imaging guarantee area, 1041-mark, 1051-mark, 1241-mark, 1043-return line. DETAILED DESCRIPTION

[0037] like Figure 1As shown, the MRI apparatus 1 includes a gantry 10 having a static magnetic field space for placing a subject therein, and a bed 105 for carrying the subject into the gantry 10. The gantry 10 and the bed 105 are placed in an examination room shielded from electromagnetic waves.

[0038] The examination room is provided with a camera 30 for displaying the subject placed on the bed 105. In addition, a display device (not shown) for displaying the image acquired by the MRI apparatus 1 is provided at the entrance of the gantry 10 or near the gantry 10, and the display device also displays the image (camera image) acquired by the camera 30. The camera image is used when the subject is placed at an appropriate position in the gantry 10 or when the receiving coil described later is attached to the subject.

[0039] There is no special restriction on the type, number and location of the camera. Figure 1 In the example, the camera 30 is set near the entrance of the gantry 10 and at two locations such as the upper part and ceiling of the inspection room. However, the number of cameras may be one or more than three, and the setting position may be a position where the camera image required for the above setting can be obtained. In addition, the camera 30 may be a camera that obtains a two-dimensional image or a stereo camera that can grasp a three-dimensional position.

[0040] like Figure 2 As shown, the gantry 10 is provided with a static magnetic field magnet 101 for generating a static magnetic field, a gradient magnetic field coil 102 for providing a magnetic field gradient to the static magnetic field space, and an RF coil 103 for generating a high-frequency magnetic field.

[0041] The gradient magnetic field coil 102 includes three sets of gradient magnetic field coils that generate gradient magnetic fields in three orthogonal axial directions. The three sets of gradient magnetic field coils are respectively connected to the gradient magnetic field power supply 112 and driven by the power supplied from the gradient magnetic field power supply 112 .

[0042] The RF coil 103 can also function as an RF receiving coil that generates a high-frequency magnetic field of a magnetic resonance frequency to excite the nuclei of atoms contained in the tissue constituting the subject, and receives nuclear magnetic resonance signals (NMR signals) generated by the subject. Figure 2 In the embodiment shown, a reception-only RF coil 104 is provided separately from the RF coil 103. Usually, the RF coil 104 is worn on the inspection site of the subject 70. Figure 1Although not shown, an RF coil may be fixed on the bed. Both the RF coils 103 and 104 can function as a transmitting coil for generating a high-frequency magnetic field and a receiving coil for receiving NMR signals. However, as an example, the RF coil 103 is a transmitting coil and the RF coil 104 is a receiving coil. The RF coil 103 is connected to a transmitter 113 including a high-frequency generator, and the RF coil 104 is connected to a receiver 114 including a detector, an A / D converter, and the like.

[0043] In the case of a multi-channel receiving coil in which the receiving coil is composed of a plurality of coil elements (hereinafter referred to as elements), the receiver 114 is composed of a plurality of receivers (a plurality of channels) each of which has an amplifier, a detector, and an A / D converter. However, the number of channels of the receiving coil and the number of channels of the receiver do not necessarily need to be consistent, and sometimes the switching connection is appropriately controlled. The output of each receiver is sent to the signal processing circuit.

[0044] The MRI device 1 includes a sequencer 115 that causes a gradient magnetic field power supply 112, a transmitter 113, a receiver 114, etc. to operate according to a prescribed pulse sequence. The sequencer 115 performs the following series of actions: irradiating a subject arranged in a static magnetic field space with a high-frequency field pulse, receiving an NMR signal from the subject, and applying a gradient magnetic field pulse to give position information to the NMR signal.

[0045] The various parts described above are collectively referred to as the imaging unit 100 of the MRI device 1. The MRI device 1 is equipped with a computer 20, which controls the various parts of the imaging unit 100 via a sequencer 115, and performs various operations related to the signals acquired by the imaging unit 100 or the images reconstructed based on the signals. Hereinafter, the control function of the computer 20 is referred to as the control unit 200. The computer 20 can be composed of a general-purpose computer or workstation equipped with a CPU or GPU and a memory, and the CPU reads and executes the program required for control or operation, so that the desired control and operation can be performed. In addition, sometimes a part of the operation performed by the computer 20 is performed by a programmable IC such as an ASIC or FPGA, and these hardware are included in the computer.

[0046] The computer 20 is connected to a UI unit 60 as an interface with a user and an external storage device 40. The UI unit 60 includes a display device 50 for displaying images acquired by the MRI apparatus 1 and a GUI, an input device (not shown), etc. In addition, a display device 50A that is arranged near the gantry 10 and displays camera images is also connected to the computer 20. In addition to displaying camera images, the display device 50A can also display images acquired by the MRI apparatus 1.

[0047] In this embodiment, the computer 20 (control unit 200) further includes a function of selecting a desired coil element or coil area from the multi-channel coil using the camera image acquired by the camera 30 and the design information of the receiving coil (channel selection function). Figure 3 As shown, the computer 20 comprises: a camera image acquisition unit 211 for acquiring a camera image projected by the camera 30; and a verification unit 215 for verifying the camera image projected of a receiving coil including a plurality of coil elements and a part of a subject wearing the receiving coil and the design information of the receiving coil, and determining the elements of the receiving coil.

[0048] The computer 20 further includes a target position determination unit 213 that determines an imaging target position in the subject, and a checking unit 215 that selects an element of the receiving coil used when imaging the target position or determines a coil area including the coil element, using the camera image, the design information of the receiving coil, and the target position determined by the target position determination unit 213. These functions are collectively referred to as a channel selection unit 210.

[0049] The design information of the receiving coil may include, for example, the size or shape and configuration of the multiple elements constituting the receiving coil, such as the CAD data of the receiving coil, and the ID (a number indicating the type or model, etc.) of the receiving coil, and may also include information that can be used to grasp the positional relationship between the appearance of the receiving coil and the elements configured inside. The information that can be used to grasp the positional relationship between the appearance of the receiving coil and the elements configured inside may be, for example, a mark or ID display portion marked on the surface of the receiving coil, or a shape feature of the receiving coil itself. In the following description, a mark is referred to as a representative of the information that can be grasped from the appearance, but in this case, the term "mark" is not restrictive and includes the above-mentioned broad information. The design information of the receiving coil is stored in, for example, the external storage device 40, and the computer 20 reads it from the external storage device 40 for the above-mentioned checking unit 215 to select the coil element.

[0050] There are several methods for the target position determination unit 213 to determine the target position, such as a method using a camera image and a method using an image acquired by an MRI device, which will be described in detail in the embodiments described later.

[0051] Furthermore, “wearing of the receiving coil on the subject” includes not only wearing of the receiving coil on various parts of the subject but also a state where the receiving coil is arranged or exists at a fixed position relative to the subject.

[0052] According to the MRI apparatus 1 having the above structure, the computer 20 (control unit 200) has a function of selecting a predetermined channel (coil element) of the receiving coil by checking the design information of the receiving coil and the camera image of the subject wearing the receiving coil, so that only the channel of the coil area including the examination part is driven for imaging, and the signal from the channel not necessary for imaging is not used for image reconstruction, so a reconstructed image with good image quality can be obtained. In addition, as the receiver 114, it is not necessary to have more receiving channels than necessary, so the structure of the receiver 114 can be simplified.

[0053] Hereinafter, specific embodiments corresponding to various receiving coils and target position identification methods will be described.

[0054] <Implementation Method 1>

[0055] In this embodiment, an embodiment is described in which the receiving coil is applied to a receiving coil which is worn so as to cover the upper surface of the imaging part of the subject and has marks on a plurality of locations on the outer side.

[0056] like Figure 3 As shown in the functional block diagram of , the computer 20 of the MRI apparatus 1 of the present embodiment includes: an image processing unit 220 that uses the NMR signal received by the receiver 114 to reconstruct an image and performs correction and other processing using the reconstructed image; a display control unit 230 that generates a display image displayed on the display device 50, 50A and controls the display; a camera control unit 240 that controls the camera unit 100 via the sequencer 115; and a channel selection unit 210 that selects the channel of the receiving coil.

[0057] The channel selection unit 210 includes a camera image acquisition unit 211, a target position determination unit 213, and a verification unit 215. The target position refers to the position of a part to be imaged or the position of an axis of a cross section including the position, and the target position can be determined by a point or a line or by a shape having a specified area (circle, quadrilateral, or the outline of a tissue, etc.).

[0058] The following is a flow chart of the processing in the channel selection unit 210 in the computer 20. Figure 4 First, before the subject is inserted into the gantry 10, the subject wears the receiving coil and lies on the bed 105. The camera image acquisition unit acquires the camera image acquired by the camera 30 and displays the camera image on the display device 50A provided near the gantry 10 (S1).

[0059] like Figure 5As shown on the left side of FIG. 3 , the camera image 300 shows the subject 70 and the receiving coil 104 worn on the imaging part of the subject (here, the chest). Figure 5 Five locations (four corners and the center of the top) are marked with markers 1041, and these markers 1041 are also reflected in the camera image.

[0060] On the other hand, the target position determination unit 213 uses the camera image or the MR image of the subject acquired in advance to acquire the target position of the subject (S2). In the present embodiment, as an example, the target position is determined using the camera image ( Figure 4 : dotted arrow) is used to illustrate the case. In this example, the examination technician or doctor (hereinafter referred to as the user) makes a specific gesture with his hand to the imaging part (target) of the subject lying on the bed 105. Here, an example of pointing to the edge of the bed is shown. In addition, the positioning laser etc. provided by the device can also be used, and it is not limited to these methods as long as the position can be shown in the camera image. Figure 5 In the example shown, the user's gesture virtually constructs a line 501 vertically in the left-right direction of the bed, and the line 501 represents the target position. In the camera image acquired in this state, the positional relationship between the subject and its target and the receiving coil can be understood.

[0061] Next, the checking unit 215 checks the information obtained from the camera image, the mark position, the target position, and the design information of the receiving coil, and determines the coil element including the target position ( S3 ). Figure 5 The figure on the right side of the figure shows the design information 400 of the receiving coil, and the checking unit 215 determines the mark position included in the design information 400 and the mark position of the camera image 300 corresponding thereto, and then determines the element corresponding to the line position based on the position relationship between the mark 1041 in the camera image 300 and the line 501. In the example shown in the figure, the coil elements 1045 are arranged in a matrix of 8×6, and the elements in the second and third rows are determined as the elements including the line 501 (S4).

[0062] In the above description, the case where the user specifies the target position in the state where the receiving coil is worn is described, but the target position may be specified in the state where the receiving coil is not worn, and the target position determination unit 213 determines the target position on the camera image using the camera image in this state. The verification unit 215 may also determine the target position on the camera image after the receiving coil is worn, using the target position determined on the camera image before the receiving coil is worn and the camera image 300 acquired after the receiving coil is worn on the subject at the bed position.

[0063] By using the information of the camera images before and after wearing, the component position and the target position can be grasped on the image coordinates of the camera image. Then, the situation of selecting the coil area including the target position by checking the mark position determined on the camera image, the target position and the design information of the receiving coil is the same as the situation of determining the target position after wearing the receiving coil.

[0064] Furthermore, when the FOV 502 of the image pickup is determined, the checking unit 215 selects an area covering the FOV 502 as the coil area 503. The FOV is usually set to 450 mm, 350 mm, etc. in the body axis direction as a default value of the device, so as long as the FOV position is determined so that the line 501 becomes the center of the FOV in the body axis direction, the coil area 503 can be selected so as to cover it. In this way, NMR signals from within and around the FOV can be received, and image quality degradation caused by reducing components can be prevented.

[0065] Then, the bed 105 is moved, and the subject is inserted into the gantry 10, and the target position is positioned so as to become the center of the magnetic field, and the image is taken (S5). In the positioning operation of the subject, the relative distance on the image is calculated in advance, and the required distance to the center of the magnetic field is calculated by associating the coordinates of the target with the device coordinate system, and the bed is moved by the corresponding distance.

[0066] In this way, the information of the channel in the coil area determined by the channel selection unit 210 is transmitted to the imaging control unit 240. The imaging control unit 240 activates the selected channel (turns on) (S6). At this time, control (for example, switching) of the channel for connecting the selected channel and the receiver is performed as needed. When all elements of the receiving coil are connected to the receiver, switching is not required. The image reconstruction processing using the received signals from each channel of the selected receiving coil is the same as that of the conventional MRI device, and the description is omitted here.

[0067] According to this embodiment, by checking the camera image showing the mark marked on the receiving coil and the target position specified by the user and the design information indicating the arrangement of the components of the receiving coil and the positional relationship between the mark and the receiver coil, the area (coil area) including the target components can be automatically determined, and only the channels in the area can be activated for imaging. Thus, it is possible to achieve improved image quality and simplification of the receiver.

[0068] <Modification 1: Modification of Coil Region>

[0069] In the above embodiment, when determining the coil area, one or more elements including the target position are selected, and the area including these multiple elements and covering the FOV is determined as the coil area. However, the coil area can also be determined by considering the imaging area that ensures the specified image quality (hereinafter referred to as the imaging guarantee area). Figure 6 As shown in (right side), the imaging guarantee area 600 is a characteristic of the device determined within the range of the distance from the magnetic field center for maintaining the uniformity of the magnetic field and the linearity of the inclined magnetic field. The checking unit 215 stores the information of the imaging guarantee area in the form of a map, or reads it from the internal memory of the computer 20 or the external storage device 40, takes the AND of the selected channel (coil area) 503 and the imaging guarantee area 600, and excludes the elements out of the imaging guarantee area 600 from the coil area 503 as the coil area.

[0070] According to this modification, by excluding elements outside the imaging guaranteed area from elements to be activated, it is possible to prevent image quality degradation caused by using signals from elements whose image quality is not guaranteed for image reconstruction.

[0071] In addition, this modification example can be applied not only to the first embodiment but also to each embodiment described below.

[0072] <Modification 2: Modification of Target Position Determination>

[0073] In the first embodiment, the case where the target position identifying unit 213 identifies the position pointed by the user's gesture or laser light is described. However, in this modification, the checking unit 215 identifies the target using the statistical anatomical database.

[0074] Specifically, first, the user specifies the target anatomical part in the computer 20. The camera image acquisition unit 211 receives the information including the user's specification together with the camera image. Figure 7 As shown, the target position determination unit 213 superimposes the position of the anatomical database 700 on the camera image 300 by a method such as non-rigid registration, analyzes and estimates the anatomical position, and determines the part as the target position.

[0075] Then, similar to the first embodiment, the checking unit 215 checks the camera image (including the marker positions of the subject and the receiving coil, and the information of the determined target position) with the design information of the receiving coil, and determines the element / coil region including the target position.

[0076] In addition, as a method of using the anatomical database, a method of specifying the target position from the examination information rather than from the camera image can also be adopted. Usually, when shooting, information such as the examination items or the examination part is input into the MRI device (computer 20) together with the information of the subject. The checking unit 215 determines the target part based on these input information and determines the part of the anatomical database. For example, if it is a heart function test, the heart is used as the target part, and if it is a shoulder joint test, the shoulder is used as the target part.

[0077] Then, the camera image and the anatomical database are checked, and the position on the camera image corresponding to the MRI image of the part determined in the anatomical database is used as the target part. According to this modification, by using the anatomical database, the target position can be determined on the camera image even without anatomical knowledge, and can be easily checked with the receiving coil design information.

[0078] <Implementation Method 2>

[0079] This embodiment is an embodiment in which the present invention is applied to an MRI apparatus having a receiving coil built into a bed on which a subject is placed. Figure 8 As shown, a mark 1051 is marked on the receiving coil built-in bed 105A, and the receiving coil design information 400A includes the positional relationship between the component arrangement and the mark 1051 .

[0080] In this embodiment, the structure and processing flow of the channel selection unit 210 are also similar to Figure 3 and Figure 4 The structure and process shown are the same. That is, the checking unit 215 checks the camera image acquired before insertion into the gantry 10 (that is, the camera image including the subject lying on the bed and the target position specified on the subject by gestures, etc.) and the design information of the receiving coil, selects the channel including the target position, and determines the coil area (S1 to S4). Similar to the first embodiment, it can also be set to include the coil area of ​​FOV. Then, only the channel of the selected coil area is opened for shooting (S5, S6).

[0081] According to this embodiment, a mark is placed on the bed that enables the position of the device coordinate system to be grasped, so that the selected coil area (target position) can be positioned to the center of the device's magnetic field in absolute coordinates using the relationship between the mark and the target position grasped by the camera image.

[0082] <Implementation Method 3>

[0083] Similar to Embodiment 1, this embodiment is an embodiment in which a channel is selected by a receiving coil 104 with a mark attached to a subject, but this embodiment is characterized in that a mark 1051 is also attached to the bed. The process of channel selection is the same as that of Embodiments 1 and 2. Figure 4 The processing of this embodiment is described.

[0084] In this embodiment, the form or shape of the receiving coil worn on the subject is not particularly limited, but the receiving coil worn on the subject is preferably Figure 5 The following description will be given by taking the same chest sheet-shaped receiving coil 104 as an example. Furthermore, the bed 105 may be a simple bed 105 or may be a bed 105A with built-in receiving coils as in the second embodiment.

[0085] First, the camera image acquisition unit 211 acquires a camera image 300 ( Figure 4 :S1). Fig. 9 As shown on the left side of , the camera image 300 shows the subject 70 lying on the bed 105A and the receiving coil 104 worn by the subject, and also shows a plurality of marks 1041 and 1051 marked on the bed 105A and the receiving coil 104, respectively.

[0086] In this embodiment, for example, as in the first embodiment, the gesture line (in Fig. 9 The target position is indicated by (not shown) to specify the target position (S2).

[0087] The checking unit 215 checks the positions and lines of the marks 1041 of the receiving coil 104 and the marks 1051 of the bed 105A in the camera image 300 with the design information 400 of the receiving coil 104 and the design information 400A of the receiving coil built in the bed (S3). As a result of the checking, first, the position of the receiving coil 104 in the bed 105A is determined based on the positional relationship between the marks 1041 of the receiving coil 104 and the marks 1051 of the bed 105A in the camera image 300. Here, the receiving coil design information 400A of the bed 105A in which the receiving coil is built includes the positional relationship between the built-in receiving coil and the bed, and the bed 105A has already known its position in the device coordinate system. Therefore, when the camera image 300 and the receiving coil design information 400 and 400A are checked, the receiving coil 104 and the target position (line position) in the device coordinate system can be determined.

[0088] If the target position is determined in the design information 400 of the receiving coil 104, the checking unit 215 selects an element including the position and determines a coil area including the selected element (S4). The coil area is determined in a manner including a FOV determined according to the target position, similarly to the first embodiment. Fig. 9 As shown on the right side of , the elements on the built-in coil side are selected in such a manner as to include the area obtained by projecting the coil area onto the built-in coil side in a direction substantially orthogonal to the coil plane of the receiving coil 104 (or in the up-down direction relative to the horizontal bed) according to the three-dimensional FOV. Here, since the elements and their arrangement or size in the bed-built-in receiving coil are usually different from those of the receiving coil 104, the coil area of ​​the built-in receiving coil is made wider than the coil area determined for the receiving coil 104, so that the coil area that reliably includes the FOV can be selected.

[0089] If the coil areas of the two receiving coils are determined, the bed 105A is moved to position the target at the center of the magnetic field (S5). At this time, since the position of the target in the device coordinate system has been determined, it is easy to position the target at the center of the magnetic field. The imaging is performed by activating the elements in the selected coil area (S6).

[0090] According to this embodiment, by also marking the bedside, the position of the receiving coil 104 worn on the subject in the device coordinate system can be determined from the camera image, thereby enabling accurate positioning. Furthermore, when an MRI image (for example, a pre-scan image described later) is used instead of a camera image when determining the target position, the target position and the position of the receiving coil (selected element) can be checked in the device coordinate system.

[0091] <Variation 3: Variation of Target Position Determination>

[0092] In the above-described first to third embodiments, the target position determination unit 213 determines the target position using the camera image and the user's designation information on the target position. However, the target position may be determined using a pre-scan image (MR image) acquired in advance by the MRI apparatus.

[0093] In this case, in the image of the pre-scan that is usually performed to determine the imaging position, etc., the target position determination unit 213 obtains information on the target position (a 2D image or a 3D image of three axes (three cross sections)) from the imaging area specified by the user such as the technician. The execution of the pre-scan and the presentation of the pre-scan image are also performed in the conventional MRI apparatus, and although this processing can be utilized, it is also possible to accept and execute the user's instruction to perform the pre-scan and the display of its image when executing the channel selection function.

[0094] Fig.10An example of a pre-scan image is shown in . In this example, a pre-scan image including three sections of the spinal cord (COR, SAG, AX) is obtained, and the user specifies the target position by setting ROI on these three sections. In this pre-scan image, the position on the image is associated with the position in the real space (the position of the device coordinate system), so by specifying the target position on the image, the target position in the real space can be grasped as the bed moves. In this variant, the target position specified by the user on such a pre-scan image is obtained as position information, and it is used for subsequent verification.

[0095] Specifically, first, the position determined on the pre-scanned image (position in the image space) is converted to a position in the real space (position in the device coordinates), and is saved as the target position. Then, the camera image is acquired while the subject is wearing the receiving coil. The checking unit 215 checks the position of the receiving coil and its markings included in the camera image and the design information (CAD data) of the receiving coil, and acquires the element position of the receiving coil. Next, the subject is moved to the center of the magnetic field of the device according to the target position information.

[0096] The checking unit 215 also obtains the position of the receiving coil in the device coordinates based on the position of the receiving coil in the camera image. For example, in Embodiment 2 or Embodiment 3, the position of the receiving coil in the device coordinates can be obtained by checking the position of the mark in the camera image showing the mark on the bed with the built-in receiving coil with the position of the mark on the bed in the device coordinate system. Next, the position of the element that moves together with the target position is determined in the device coordinate system, and the coil area including the target position is determined. When determining the coil area, the FOV is considered as in Embodiment 1 and Modification 1, or the imaging guarantee area is further considered.

[0097] According to this modification, since the target position in the device coordinate system is determined based on the pre-scan image actually observed inside, it is possible to determine the target position with higher accuracy than the target position specification using a camera or laser, etc., which only obtains information based on appearance. In addition, when positioning the subject in the gantry, the target position can be easily positioned at the center of the magnetic field.

[0098] <Implementation Method 4>

[0099] Embodiments 1 to 3 are examples of providing a plurality of marks readable by a camera on a receiving coil, and selecting a specified component by comparing the mark position with the mark position and component arrangement included in the design information of the receiving coil, but this embodiment is characterized in that marks are provided at specified intervals on the receiving coil, thereby correcting the position of the mark of the receiving coil in the camera image.

[0100] Since the structure of the channel selection unit 210 is the same as that of the above embodiment, the following reference is made to Fig.11 and Fig.12 , the description will focus on the points that are different from the above-mentioned embodiment.

[0101] Fig.11 3 is a diagram schematically showing a camera image 300 of a subject wearing a receiving coil 104. As shown in the figure, a plurality of markers 1041 are provided at equal intervals (interval = a) on the receiving coil 104. For ease of explanation, only a portion 104A of the receiving coil 104 provided with five markers 1041 is shown at the bottom of the figure.

[0102] The camera image 300 shows the subject, the receiving coil 104, and the mark 1041. However, if the receiving coil 104 is a deformable or flexible receiving coil such as a blanket, the position of the mark 1041 is different from that in a planar state due to the bending (deformation) of the receiving coil 104. Therefore, it is impossible to directly check with the two-dimensional design information of the receiving coil.

[0103] In this embodiment, the deformation of the receiving coil 104 is estimated based on the position of the mark 1041 of the receiving coil 104 and corrected before verification. Fig.12 As shown in the camera image 300, if the distance between the markers is not the flat distance "a" but "b" as between the first and second markers and between the fourth and fifth markers, it can be estimated that the receiving coil 104 has generated an angle θ (=cos -1 By reflecting this deformation on the distance between markers of the receiving coil 104 and calculating the distance between markers, the distance between markers in a planar state can be obtained.

[0104] In addition, although Fig.12 Although not shown, the case where the target position of the subject is determined based on the camera image or the MR image acquired in advance is the same as that in the above-mentioned embodiment or modification example, and the description thereof is omitted here.

[0105] And, in Fig.11 In the embodiment, marks are provided at predetermined intervals on the receiving coil 104, but Fig.13 As shown, the receiving coil 104 may be fixed with a fixing tape 124. In this case, the fixing tape 124 may be provided with a fixing tape 124. Fig.11 The same mark 1241. Even if the fixing tape 124 is provided on the mark 1041 on the receiving coil 104 by providing the mark on the fixing tape 124, it can be accurately identified because the fixing tape itself has the mark 1241. By providing the mark on the object that is considered to be provided on the outermost side, the mark can be accurately identified.

[0106] Then, similar to the first embodiment, the arrangement of the calibrated markers 1041 or 1241 , the target position, and the design information of the receiving coil 104 are checked to select a channel including the target position, and determine a coil area including the selected channel and FOV.

[0107] According to this embodiment, by marking a mark on the fixing tape for fixing the receiving coil to the subject and introducing it into the camera image, errors in the two-dimensional position information (distance between elements) obtained in the camera image caused by the deflection of the receiving coil can be corrected.

[0108] <Implementation method 5>

[0109] Embodiments 1 to 4 are embodiments of receiving coils of a type in which the receiving coil is placed on the subject or the subject is arranged on the receiving coil, but this embodiment is an embodiment of a receiving coil of a type in which the receiving coil is folded in half or wrapped and worn on the subject. Figure 14 to Figure 16 This embodiment is described. Fig.16 In, it means Figure 4 The same blocks of the same process are represented by the same symbols, and the description thereof is omitted.

[0110] Fig.14 The camera image 300 shows a state in which the target position is located near the upper arm end (shoulder) of the subject, and the blanket-shaped receiving coil 104 is folded back at the shoulder of the subject so as to surround the target position and is arranged on the chest side and the back side. The receiving coil 104 arranged on the chest side and the mark 1041 marked thereon are shown in the camera image. The target position can be determined by designation such as gestures as in the first embodiment, but in this example, it is determined based on the pre-scan image (S1, S2).

[0111] When comparing the camera image 300 (mark position) with the design information of the receiving coil, the checking unit 215 detects the return line 1043 of the camera image 300 and specifies a line corresponding to the return line 1043 on the design information ( S31 ). Fig.15The left side of shows the return line 1043 determined based on the camera image, the portion of the receiving coil located on the chest side of the subject (the portion not hidden), and the mark 1041. The target position of the camera image obtained based on the position information obtained based on the camera image and the target position determined by the target position determination unit 213 (in the case of the pre-scan image, the position information in the device coordinate system) is used to select the element including the range of the target position, and determine the coil area 503 (S41). In addition, as described in the above-mentioned modification example, the verification of the camera image and the real space (device coordinate system) can be performed by verifying the camera image with a mark whose position can be determined in the device coordinate system.

[0112] Next, the return line in the design information (CAD data) 400 of the receiving coil is determined, and an element on the lower side (hidden portion) symmetrical to the selected element line with respect to the return line is selected on the CAD data ( S42 ).

[0113] In addition, in this example, Fig.15 As shown on the right side of , it is assumed that the target position exists at approximately equal distances from the return line 1043 detected in the camera image, but in the case where the thickness of the subject is large, the distance between the return line and the target position may be different on the front side and the back side of the receiving coil depending on the position of the camera. In this case, a correction value considering the thickness of the subject may be added to the return line. For example, a predetermined amount (<thickness ÷ 2> × arbitrary coefficient) may be offset in the direction away from the target position relative to the position detected as the return line, and it may be used as the return line.

[0114] Then, similarly to other embodiments, the target position is moved to the center of the magnetic field, and the elements of the selected coil area are activated to perform imaging (S5, S6). In addition, in the illustrated example, a single return line is shown, but in the case of a receiving coil of a type wound around a trunk, where there are return lines on the left and right, this embodiment can also be applied in the same manner.

[0115] According to this embodiment, for a receiving coil that is worn so that there are two or more receiving coil parts (front and back) sandwiching a target position, an appropriate coil area can be determined for each part and activated, thereby being able to receive signals from the target area with high sensitivity.

[0116] <Modification 4: Modification of Camera Image>

[0117] In the above embodiment and modification, the case where a two-dimensional camera image of the subject before insertion into the gantry is captured by the camera is mainly described. However, depending on the type, function, and configuration of the camera 30, the following camera images may also be used.

[0118] For example, when the camera has a fisheye lens or a tracking mechanism for a receiving coil and is set at a position where it can capture the state of the inside of the hole of the gantry (such as the entrance to the gantry or inside the hole), the subject from the position where the receiving coil is worn to the position where the magnetic field is configured can be captured as a camera image. Therefore, in addition to checking with the design information of the receiving coil, positioning using the camera image can also be performed.

[0119] Furthermore, if the camera has a dynamic image function, it is possible to capture the state from before the coil is worn to after the coil is worn. By overlaying the position information of the receiving coil mark on the target position after the target position is determined before wearing, the camera image data can include the target position and the receiving coil position information without specifying the target position using a projector, etc. Thus, even if an object that blocks the mark is placed on the receiving coil when the subject is inserted into the gantry, the camera image can be checked against the design information of the receiving coil without any hindrance.

[0120] As mentioned above, although embodiment and modification of this invention were demonstrated, these can be combined suitably as long as there is no technical contradiction, and such combination is also included in this invention.

Claims

1. A magnetic resonance imaging device, comprising: an imaging unit having a multi-channel receiver for receiving a nuclear magnetic resonance signal generated by a subject; and a control unit for controlling the imaging unit. The magnetic resonance imaging device is characterized in that The control unit comprises: a camera image acquisition unit for acquiring an image from a camera disposed in the magnetic resonance imaging device; a target position determining unit that determines a target position for imaging in the subject; and The checking unit checks the camera image acquired by the camera image acquisition unit and showing the subject wearing a receiving coil including multiple coil elements, and the design information of the receiving coil, and determines the coil elements of the receiving coil that cover the target position determined by the target position determination unit.

2. The magnetic resonance imaging device according to claim 1, characterized in that The target position specifying unit receives a position specification by a user using a camera image showing the subject before the receiving coil is mounted, and specifies the specified position as the target position.

3. The magnetic resonance imaging device according to claim 2, characterized in that: The target position identification unit analyzes the camera image including the position designated by the user using an anatomical database, and identifies a predetermined site in the anatomical database as a target position.

4. The magnetic resonance imaging device according to claim 1, characterized in that: The target position specifying unit receives position designation by a user using a pre-scan image of the subject acquired in advance by the imaging unit and displayed on a display device, and specifies the designated position as the target position.

5. The magnetic resonance imaging device according to claim 1, characterized in that: The receiving coil is marked with a mark, and the design information of the receiving coil includes the positional relationship between the coil element and the mark, The checking unit checks the mark position included in the camera image and the design information of the receiving coil to determine the coil element of the receiving coil.

6. The magnetic resonance imaging device according to claim 1, characterized in that: The checking unit determines the coil region so that the coil region in which the coil elements are arranged to cover the target position includes a predetermined FOV.

7. The magnetic resonance imaging device according to claim 1, characterized in that: The checking unit acquires information of an imaging guaranteed area based on characteristics of a static magnetic field and a gradient magnetic field of the magnetic resonance imaging apparatus, and excludes coil elements not included in the imaging guaranteed area.

8. The magnetic resonance imaging device according to claim 1, characterized in that: The magnetic resonance imaging device further comprises a bed. The bed has a built-in receiving coil and the subject is placed thereon, and the bed is provided with a mark indicating the position of the built-in receiving coil. The checking unit calculates the position of the receiving coil on the device coordinates based on the camera image showing the subject and the bed mark. The checking unit determines a coil element of the receiving coil that covers the target position using the coil position on the device coordinates, the target position determined by the target position determining unit, and the design information of the receiving coil.

9. The magnetic resonance imaging device according to claim 1, characterized in that: The magnetic resonance imaging device further comprises a bed. The subject is placed on the bed, and a mark is provided on the bed at a position where a camera image can be acquired. The checking unit calculates the position of the receiving coil on the device coordinates based on a camera image showing the subject wearing the receiving coil and a mark on the bed, and uses the coil position on the device coordinates, the target position determined by the target position determining unit, and the design information of the receiving coil to determine the coil element of the receiving coil covering the target position.

10. The magnetic resonance imaging device according to claim 9, characterized in that: The bed has a second receiving coil built in, and the mark is a mark indicating the position of the built-in second receiving coil.

11. The magnetic resonance imaging device according to claim 10, characterized in that: The checking unit sets a region of the second receiving coil as a coil selection region, wherein the region of the second receiving coil is obtained by projecting a region where coil elements of the receiving coil worn on a subject are arranged in a direction orthogonal to the bed.

12. The magnetic resonance imaging device according to claim 1, characterized in that: The receiving coils are marked with marks at equal intervals. The checking unit calculates the deflection of the receiving coil based on the intervals of the marks included in the camera image, and after correcting the deflection of the receiving coil, checks with the design information of the receiving coil to determine the coil element of the receiving coil.

13. The magnetic resonance imaging device according to claim 1, characterized in that: The receiving coil is fixed to the subject using a flexible belt, and the flexible belt is marked with marks at equal intervals along its length. The checking unit calculates the deflection of the receiving coil based on the intervals of the marks included in the camera image, and after correcting the deflection of the receiving coil, checks with the design information of the receiving coil to determine the coil element of the receiving coil.

14. The magnetic resonance imaging device according to claim 1, characterized in that: The target position determination unit includes a detection unit, The detection unit detects a return line of the receiving coil from a camera image showing the subject wearing the receiving coil. The checking unit identifies another partial coil element of the receiving coil that is line-symmetrical with the coil element identified for a portion of the receiving coil reflected in the camera image, with the return line interposed therebetween, and identifies the partial coil element and the other partial coil element as coil elements of the receiving coil.

15. The magnetic resonance imaging device according to claim 1, characterized in that: The camera is a camera having any one of a fisheye lens, a subject tracking mechanism and a dynamic image function, The camera image acquisition unit acquires information of a camera image including a temporal change or a spatial change of a subject as the camera image.

16. A method for automatically selecting channels of a multi-channel receiving coil, which is a method for selecting coil elements of a multi-channel receiving coil used in a magnetic resonance imaging device, the method comprising the following steps: acquiring an image from a camera disposed in the magnetic resonance imaging device; determining a target position in a subject wearing the receiving coil; and A camera image showing a subject wearing a receiving coil including a plurality of coil elements, the target position, and design information of the receiving coil are collated to identify the coil elements of the receiving coil including the target position.

17. The automatic channel selection method for a multi-channel receiving coil according to claim 16, characterized in that: The step of determining the target position includes the step of accepting a user's designation of a part in the displayed camera image, and determining the accepted part as the target position.

18. The automatic channel selection method for a multi-channel receiving coil according to claim 16, characterized in that: The step of determining the target location comprises: The step of analyzing the camera images using the anatomical database; and A step of determining one of a plurality of parts included in the anatomical database as a target part, and determining a position of the camera image corresponding to the determined target part as the target position.

Images