JP2007252741A - Magnetic resonance imaging system and coil unit for using for magnetic resonance imaging system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic resonance imaging system where the noise is generated by applying the gradient magnetic field to the magnetostatic field during imaging with the MRI system but it can be hardly transmitted to the subject, and also to provide a coil unit used for the magnetic resonance imaging system. <P>SOLUTION: A coil unit 4 is used for the magnetic resonance imaging system reconstructing images based on the magnetic resonance signal which is radiated from the subject in the magnetostatic field charged with the gradient magnetic field, and it is characterized in that the coil unit 4 is equipped with an upper top panel 51 for laying the subject, a bed 50 which is placed along the upper top panel at the lower side of the upper top panel and have the lower coil element receiving the magnetic resonance signal radiate from the subject, and a cover 40 capable of covering the subject and closing tightly at the upper side of the bed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnetic resonance imaging apparatus and a coil unit used in the magnetic resonance imaging apparatus, and more particularly to a soundproofing technique in the coil unit.

  Examination with a magnetic resonance imaging apparatus (hereinafter referred to as an MRI apparatus) detects a weak magnetic resonance signal emitted from a human body after applying a high-frequency magnetic field to a subject in a static magnetic field, and uses the magnetic resonance signal as an image. It is done by becoming. At this time, since a position in the subject cannot be identified with a uniform static magnetic field, it is necessary to apply a gradient magnetic field with a gradient. However, a Lorentz force is generated in the gradient magnetic field coil for generating the gradient magnetic field, and further, this gradient magnetic field is generated by switching at a predetermined frequency, so that the vibration is generated by the Lorentz force generated according to the frequency. Noise is generated.

  For this reason, various noise reduction designs have been made, such as using anti-vibration rubber, but in order to meet the demand for improved performance, such as shortening the shooting time and improving image quality, The rise of the magnetic field when it is generated is made steep and the noise tends to increase.

  On the other hand, there is a high frequency coil (hereinafter referred to as an RF coil) having an antenna function for receiving a magnetic resonance signal. Since the magnetic resonance signal received by this RF coil is very weak, a high S / N ratio is required for the RF coil. Conventionally, an RF coil to be brought into close contact with the diagnostic site as much as possible has been prepared for each diagnostic site. It was used for inspection (for example, refer to Patent Document 1).

  By the way, when inspecting an infant using an MRI apparatus, in order to stop the movement of the infant being photographed, it is often performed by putting the RF coil together with the RF coil in the gantry after using a sleeping agent or the like. However, even in the sleep state due to the sleeping agent, sleep is disturbed by noise and the user is awakened. As a result, the infant moves and a desired image cannot be obtained.

  Moreover, since there is a concern about the damage to infants and infants caused by the sleeping agent, it is desirable to suppress the use of the sleeping agent if possible. Therefore, it is unlikely to increase the amount of sleeping agent to maintain infant sleep. Therefore, further noise countermeasures are required.

JP 2003-153878 A

  The present invention has been made in view of the above circumstances, and an object thereof is to make it difficult to transmit noise generated by applying a gradient magnetic field to a static magnetic field to a subject during imaging by an MRI apparatus. An object of the present invention is to provide a magnetic resonance imaging apparatus and a coil unit used in the magnetic resonance imaging apparatus.

  In order to solve the above problems, the invention according to claim 1 is a coil used in a magnetic resonance imaging apparatus that reconstructs an image based on a magnetic resonance signal emitted from a subject in a static magnetic field to which a gradient magnetic field is applied. An upper top plate for the subject to lie down, and a lower coil that is disposed along the upper top plate below the upper top plate and receives a magnetic resonance signal radiated from the subject The bed is provided with an element, and a lid capable of covering and sealing the subject is provided above the bed.

  The invention according to claim 12 is provided with a subject in a static magnetic field having a cylindrical opening, including a first bed that can be taken in and out of the opening, and to which a gradient magnetic field in the opening is applied. A magnetic resonance imaging apparatus for reconstructing an image based on a magnetic resonance signal radiated from an upper top plate for a subject to lie down, along the upper top plate below the upper top plate A couch disposed and having a lower coil element that receives a magnetic resonance signal radiated from the subject; a lid provided on the upper side of the couch so as to cover and seal the subject; and an upper side of the lid An upper coil element that is provided so as to be movable in the body axis direction of the subject along, and that receives a magnetic resonance signal radiated from the subject including a coil having a smaller number of coils than the lower coil element; A coil unit placed on the first bed, and measuring the intensity distribution of magnetic resonance signals received by the upper coil element and the lower coil element, and based on the intensity distribution, And an information providing means for providing information indicating the position of the upper coil element with respect to the lower coil element.

  According to the present invention, since the lid that covers the subject and can be sealed is provided on the upper side of the bed, the subject is accommodated in the sealed interior, so that noise generated by applying a gradient magnetic field is applied to the subject. Difficult to communicate.

[First Embodiment]
(Machine configuration)
An MRI apparatus (magnetic resonance imaging apparatus) according to a first embodiment will be described with reference to the drawings.

  FIG. 1 is an external view of the MRI apparatus of the present embodiment. As shown in FIG. 1, the MRI apparatus has a bed part 1 (first bed) on which a subject P (not shown) is placed, and a weak magnetic resonance signal emitted from the subject P by generating a magnetic field. It comprises a magnetic field generator 2 to be detected and a console 3 (not shown) that controls the entire system and performs image reconstruction.

  The couch unit 1 (first couch) accommodates the top plate unit 11 for the subject P to lie down and the top plate unit 11 so as to be movable in the direction of the opening 21 of the magnetic field generator 2. The rail part 12 which guides the top plate part 11 moved by the part moving mechanism so as to be put in and out of the opening part 21, and the elevating part 13 which holds the rail part 12 and moves up and down by a not-shown top plate elevating mechanism. Is done.

  Further, in the present embodiment, a capsule-type coil unit 4 that is a coil unit of the present invention that accommodates the subject P inside is mounted on the top plate 11 and used. Moreover, although the capsule type coil unit 4 of the size which accommodates the infant is shown in FIG. 1, it is not restricted to this, The magnitude | size which accommodates a general adult may be sufficient.

  FIG. 2 is a schematic cross-sectional view for explaining the configuration of the bed unit 1 and the magnetic field generator 2.

  The magnetic field generator 2 includes a static magnetic field magnet 102 that generates a static magnetic field in the axial direction of the cylindrical opening 21, a shim coil 103 that equalizes the static magnetic field, and gradient magnetic fields in the X-axis, Y-axis, and Z-axis directions, respectively. A gradient magnetic field coil 101 to be generated and a transmission coil 104 for applying a high-frequency magnetic field to the subject P are provided. In the present embodiment, the axial direction (static magnetic field direction) of the opening 21 is the Z axis, the horizontal axis orthogonal to the Z axis is the X axis, and the vertical axis is the Y axis. In this example, the static magnetic field magnet 102 is a permanent magnet, but may be a superconducting magnet or the like.

  As shown in FIG. 2, the capsule coil unit 4 moves in the direction of the opening 21 of the magnetic field generator 2 together with the top plate 11 while being placed on the top plate 11. At the time of inspection, the inspection is performed in a state where it is placed in the opening 21 as shown in FIG. At this time, the subject P is accommodated in the capsule coil unit 4 so that the body axis is in the static magnetic field direction, that is, the Z axis.

  The air control unit 120 is disposed outside the opening 21 and includes an air pump connected to an air tube 121 including an intake tube and an exhaust tube of the capsule coil unit 4. This is for supplying and exhausting air inside the coil unit 4. The RF coil connector board 110 is for sending the magnetic resonance signal received by the capsule coil unit 4 to the magnetic field generator 2.

  FIG. 3 is a perspective view showing the capsule coil unit 4 in a closed state. The capsule coil unit 4 is mainly composed of a capsule bed portion 50 as a bed (second bed) of the present invention and a capsule lid 40 which is a lid of the present invention.

  The capsule lid 40 is disposed on the capsule bed portion 50, and for example, the short side direction from the front side to the back side in FIG. 3 is formed in an arc-shaped convex shape so as to cover the subject P (not shown). ing. Further, the back side of the capsule lid 40 is fixed to the capsule bed portion 50 by a hinge mechanism 44 made of a hinge or the like. FIG. 4 shows a cross-sectional view from the front side to the back side of the capsule lid 40 of the capsule coil unit 4. The capsule lid 40 opens and closes in the opening and closing direction of the arrow shown in FIG. 4 with the rotation center determined by the hinge mechanism 44 as a fulcrum. Further, the front side is locked by a lock portion 45 provided in the capsule bed portion 50 when the capsule lid 40 is closed. Further, when the capsule lid 40 is closed, the capsule lid 40 is brought into contact with the capsule bed portion 50 so as to press the packing 57 having flexibility such as rubber. Thereby, the inside is sealed and the inside is sound-insulated. For example, the packing 57 may be provided in the capsule bed part 50. Here, the term “sealing” is a term used to mean that it is cut off from the outside, and aims at a soundproofing effect by sealing.

  The capsule lid 40 is formed of a transparent material such as plastic such as an acrylic plate or glass, and the state of the subject P inside can be visually confirmed. Further, the capsule lid 40 is not limited to a transparent material but may be an opaque material or a translucent material. In addition, a soundproof material or the like may be attached to the capsule lid 40. In addition, when using opaque / translucent materials or attaching soundproofing materials, it is possible to check the inside by installing a CCD camera, etc., or to incorporate an ecological monitor (for example, a pulse sensor). Then, the patient's condition can be confirmed by showing the change over time based on the output from the ecology monitor. Further, a transparent material may be used for a part of the capsule lid 40 so that the inside can be confirmed. However, the cost is lower when a transparent material is used.

3 and 4, on the upper side of the capsule lid 40, the upper coil portion 41 is a capsule which is the direction indicated by the arrow in FIG. 3 as the movement direction, in other words, the body axis direction of the subject P. The mold coil unit 4 is provided so as to be movable along the capsule lid 40 in the longitudinal direction.
Specifically, the rail portion 42 is formed from one end side to the other end side in the longitudinal direction on the near side and the back side of the capsule lid 40, and the upper coil portion end portion 43 is inserted into the rail portion 42, The upper coil portion 41 moves while being guided by the rail portion 42. FIG. 5 shows an enlarged view of the rail portion 42. The rail portion 42 is constituted by a narrowed portion formed by a bowl-shaped bend, and the upper coil portion end portion 43 is inserted into the narrowed portion and guided. The

  FIG. 6A shows the upper coil element 105 as viewed from above the upper coil portion 41. The upper coil element 105 is an RF coil provided in the upper coil unit 41 and having an antenna function for receiving a weak magnetic resonance signal radiated from the subject P. The upper coil element 105 of the present embodiment is composed of, for example, a plurality of looped coils. For example, one coil is formed in a rectangular loop shape as shown in FIG. 6 (b), and the coil is arranged with a predetermined overlap in the short direction of the capsule coil unit 4 to form one coil row. Further, a coil array in which the coil rows are arranged in the longitudinal direction of the capsule coil unit 4 is used. For example, as shown in FIG. 6B, two coil rows are arranged. The shape of the coil loop may be circular.

  Each coil of the upper coil element 105 is connected to a connection board (lid) 124 via a signal line (not shown), and the connection board (lid) 124 is further connected to a capsule bed portion 50 described later via a lid cable 126. Connected to a connection board (main body) 125.

  Further, although the upper coil element 105 is partially provided with respect to the capsule lid 40, the desired position of the subject P can be inspected by moving the upper coil portion 41. Further, the state of the internal subject P can be visually recognized through a transparent member from a portion where the upper coil element 105 is not present.

  FIG. 7 is a perspective view showing the capsule coil unit 4 in an open state. As shown in FIG. 7, a mat 51 (upper top plate) is placed inside the capsule bed portion 50. The mat 51 is in the form of a sheet having a predetermined thickness. For example, the mat 51 is configured by covering a foam material such as sponge with a sheet of vinyl chloride or the like. The mat 51 is formed with a concave portion 52 for accommodating the subject P with the body axis as the longitudinal direction of the capsule coil unit 4. Further, the mat 51 is provided with three belts A53 and B54 along the concave portion 52 in the body axis direction. The belt A53 and the belt B54 are not shown, but a Velcro tape (registered trademark) or the like is fixed thereto, and the subject P accommodated in the concave portion 52 is fixed to the belt A53 and the belt B54 with the Velcro tape (registered trademark). Can be fixed. Incidentally, the capsule-type coil unit 4 is placed on the bed unit 1 so that the longitudinal direction of the capsule-type coil unit 4 is the direction of the static magnetic field of the magnetic field generator 2.

  Further, an air duct A55 and an air duct B56 are provided in the vicinity of the front side end portion and the back side end portion, respectively. Although not shown, one of the air duct A55 and the air duct B56 is connected to the exhaust tube of the air tube 121, and the other is connected to the intake tube of the air tube 121 to supply and exhaust air inside the capsule coil unit 4. Used for. Further, the air tube 121 has a length to be connected to the air control unit 120 disposed outside the opening 21 of the magnetic field generator 2. Therefore, since sealing is maintained, intrusion of sound generated from the gradient magnetic field coil 101 in the opening 21 can be avoided.

  FIG. 8 is a diagram illustrating the internal configuration of the capsule couch unit 50. FIG. 8C is a schematic cross-sectional view showing the configuration of the capsule bed portion 50. As shown in FIG. 8 (c), the capsule bed portion 50 is provided with the above-described mat 51 and the like, and is disposed below the lower coil portion 58 including the lower coil element 106 and the lower coil portion 58. An elevating mechanism unit 80 that moves the unit 58 up and down is included.

  FIG. 8A is a top view showing the configuration of the lower coil portion 58. As shown in FIGS. 8A and 8C, the lower coil portion 58 includes a base 59 that is a rectangular plate-like body, nuts 85 that are fixed in the vicinity of the four corners of the base 59, and a lower portion on the upper surface. And a coil element 106.

  The lower coil element 106 is an RF coil that is arranged below the subject P and has an antenna function for receiving a weak magnetic resonance signal radiated from the subject P. It comprises a plurality of coils. For example, one coil is formed by arranging coils formed in a rectangular loop shape with a predetermined overlap in the short direction of the capsule-type coil unit 4 to form a single coil row, and the coil row is further formed as a capsule-type coil. The units 4 are arranged in the longitudinal direction. Since the lower coil element 106 needs to be arranged over the whole body of the subject P, more coil rows are arranged than the upper coil element 105.

  Each coil of the lower coil element 106 is connected to a connection board (main body) 125 via a signal line (not shown). As described above, the lid cable 126 is connected to the connection board (main body) 125, and the connection board (main body) 125 is connected to the RF coil connector board 110 via the main body cable 122.

  Further, a screw hole at the center of the nut 85 is formed, and the base 59 has a through hole substantially the same as the screw hole at the position of the screw hole. The lower coil portion 58 is supported by four support columns 81. Further, in the initial state, each support column 81 is screwed so as to keep the lower coil portion 58 horizontal, and when each support column 81 rotates in conjunction with each other, the nut 85 is fixed to the base 59 so that it does not rotate. It moves up and down in the axial direction of 81. Therefore, the lower coil part 58 moves up and down according to the rotation direction.

  Here, the configuration of the elevating mechanism unit 80 including the support column 81 for moving the lower coil unit 58 up and down will be described with reference to FIG. FIG. 8B is a schematic top view showing the configuration of the lifting mechanism unit 80.

  The elevating mechanism 80 includes a dial 86 that partially protrudes outside the capsule couch 50. The dial 86 is pivotally supported by a support means (not shown) so that an operator can turn the protruding portion with a finger or the like. Further, a gear is formed on the dial 86, and the gear formed on the dial 86 and the idle gear B84 are engaged. Further, the idle gear B84 is engaged with a gear B83 and an idle gear A82 provided on the two columns 81. The idle gear A82 is engaged with another idle gear B84 located on the opposite side of the idle gear B84 that engages with the gear formed on the dial 86, and the idle gear B84 includes The gear B83 provided on the remaining two support columns 81 is engaged. Although not shown, each gear is pivotally supported by a support means (not shown) so as to be rotatable. Therefore, when the operator rotates the dial 86, the four gears B83 are rotated in the same direction by the respective gears, and the four support columns 81 are rotated to move the lower coil portion 58 up and down.

  As described above, the distance between the upper coil element 105 and the subject P can be adjusted by providing the elevating mechanism 80 for moving the lower coil 58 on which the mat 51 or the like is placed up and down. . Therefore, even if the distance between the upper coil element 105 and the subject P changes depending on the size of the subject P, it can be made appropriate. On the other hand, the lower coil element 106 and the subject P maintain a certain positional relationship with the mat 51 interposed therebetween.

  In the present embodiment, the coil elements are provided on the upper side and the lower side of the subject, but a configuration provided only on the lower side may be employed.

(Control configuration)
Next, the control configuration of the MRI apparatus of the present embodiment will be described with reference to FIG. FIG. 9 is a block diagram showing a control configuration of the MRI apparatus of the present embodiment.

  The bed unit 1 includes a top plate moving mechanism driving unit 131 that drives the above-described top plate moving mechanism and a top plate lifting mechanism driving unit 132 that drives the top plate lifting mechanism.

  The magnetic field generator 2 includes a shim coil power supply 203, a gradient magnetic field power supply 201, a transmitter 204, and a receiver 205.

  The shim coil power supply 203 supplies current to the shim coil in order to make the static magnetic field uniform. In addition, the gradient magnetic field power supply 201 generates a gradient magnetic field by supplying a pulse current to each of the x, y, and z coils that generate gradient magnetic fields in the X-axis, Y-axis, and Z-axis directions of the gradient magnetic field coil unit, respectively.

  Further, the transmitter 204 supplies an RF current pulse having a Larmor frequency for exciting a nuclear magnetic resonance by applying a high frequency magnetic field to the subject P to the transmission coil 104. The receiver 205 takes in a magnetic resonance signal sent from the capsule coil unit 4 via the RF coil connector board 110 and performs various signal processing such as preamplification, intermediate frequency conversion, position detection, low frequency amplification, and filtering. Then, A / D conversion is performed to generate digital data of the magnetic resonance signal.

  FIG. 10 is a block diagram showing the connection configuration of the capsule coil unit 4. The magnetic resonance signal received by the upper coil element 105 is transmitted to the connection board (lid) 124 via a signal line (not shown). Further, the magnetic resonance signal sent to the connection board (main body) 125 via the lid cable 126 and received by the lower coil element 106 is sent to the connection board (main body) 125 via each signal line (not shown). These magnetic resonance signals are sent to the RF coil connector board 110 via the main body cable 122.

  The air control unit 120 is used to supply and exhaust air inside the capsule coil unit 4 by operating an air pump or the like. In addition, although not shown, a means for detecting whether or not the air tube 121 is connected to an air pump or the like is provided, and it has a function as a control means for operating the air pump when it is detected that the air tube 121 is connected. .

  The console 3 includes a control / calculation unit 31, an operation unit 32, a display unit 33, and a storage unit 34.

  The control / arithmetic unit 31 includes a CPU and an internal memory (not shown), functions as a control unit that controls each unit of the entire apparatus in accordance with a control program stored in the storage unit 34 and an input from the operation unit 32, and magnetic resonance. It has a function as a computing means for reconstructing image data from digital signal data. For example, the gradient magnetic field power supply 201, the transmitter 204, the receiver 205, etc. are controlled, the digital data of the magnetic resonance signal from the receiver 205 is received, and the digital data is stored in the k space (also called Fourier space or frequency space) by the internal memory. Data is arranged, and this digital data is subjected to two-dimensional or three-dimensional Fourier transform for each set to reconstruct the image data in real space. In addition, for example, upon receiving an elevation instruction from the operation unit 32, the top unit elevating mechanism driving unit 131 is controlled to operate the top unit elevating mechanism, and the top unit 11 from the operation unit 32 is operated. In response to the input of the instruction to move, the top plate moving mechanism driving unit 132 is controlled to operate the top plate moving mechanism.

  The storage unit 34 stores a control program, reconstructed image data, and the like.

  The display means 33 is a so-called monitor constituted by a liquid crystal display (LCD) or a cathode ray tube (CRT), and is controlled by the control / calculation unit 31 to display image data and the like. Therefore, the control / calculation unit 31 has a function as display control means.

  The operation unit 32 is used to input various instruction information from the operator, various information such as a password, etc., and although not shown, various keys (alphabetic keys, numeric keys, etc.), a mouse, a trackball, etc. are connected or installed. ing.

  In the capsule-type coil unit 4 configured as described above, for example, a subject P of an infant who is in a sleeping state with a sleeping agent is placed and fixed using a belt A53 and a belt B54. Then, the capsule lid 40 is closed and locked by the lock unit 45. Thus, the capsule-type coil unit 4 containing the subject P is placed on the top 11 so that the longitudinal direction is the direction of the static magnetic field, and the operation unit 32 is operated to open the opening of the magnetic field generator 2. Move to 21 and perform inspection. Since the capsule coil unit 4 is hermetically sealed, it is possible to shield noise when generating a gradient magnetic field, and hardly disturb sleep.

  In the present embodiment, the subject lying on the capsule bed is covered with the lid from the upper side. However, a configuration in which the cylindrical lid is sealed from the front and rear or from the left and right is also conceivable.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to the drawings. In the following, detailed description of configurations substantially similar to those of the first embodiment will be omitted, and different points will be mainly described.

  As described in the first embodiment, the upper coil portion 41 is movably provided. However, if the upper coil element 105 of the upper coil portion 41 and the lower coil element 106 of the lower coil portion 58 are misaligned, specifically, each coil row is misaligned in the moving direction of the upper coil portion 41. Optimal image cannot be collected. Accordingly, in the present embodiment, in order to correct the deviation, the distribution of the intensity of the magnetic resonance signal received by the upper coil element 105 and the lower coil element 106 is used as information indicating the position of the upper coil element 105 with respect to the lower coil element 106. The amount of deviation between the upper coil element 105 and the lower coil element 106 is obtained and provided from (hereinafter, sometimes referred to as sensitivity distribution).

(Control configuration)
In the present embodiment, the control / calculation unit 31 reconstructs each of the magnetic resonance signal digital data obtained for each of the upper coil element 105 and the lower coil element 106 into image data, for example, image data. Has a function as a sensitivity distribution acquisition means for obtaining a sensitivity distribution in the moving direction from the signal intensity at the center line of the image indicated by and a function for obtaining a deviation amount from the sensitivity distribution. In addition, the display unit 33 has a function as display control means for displaying the shift amount as information for correcting the shift between the position of the upper coil element 105 and the position of the lower coil element 106. Therefore, the control / calculation unit 31 has a function as information providing means of the present invention.

  Hereinafter, the above-described information provision performed by the control / calculation unit 31 will be specifically described.

  The controller / arithmetic unit 31 first scans and acquires digital data of magnetic resonance signals received by the upper coil element 105 and the lower coil element 106 via the RF coil connector board 110 and the receiver 205. Next, sagittal cross-sectional image data is reconstructed for each of the upper coil element 105 and the lower coil element 106.

  FIG. 11 is a schematic diagram for explaining a sagittal section. FIG. 11A is a top view of the capsule coil unit 4 viewed from above, and FIG. 11B is a front view of the capsule coil unit 4 viewed from the front side of FIG. In the capsule coil unit 4 shown in FIG. 11, the subject P is fixed in the longitudinal direction of the capsule coil unit 4 by the belt A53 and the belt B54 shown in FIG. 7, and the capsule coil unit 4 is attached to the body axis of the subject P. Is placed in the opening 21 of the magnetic field generator 2 so as to coincide with the Z-axis direction (static magnetic field direction). In this state, the control / arithmetic unit 31 executes a scan, and obtains tomographic image data of a cross section at the center in the X-axis direction of the capsule coil unit 4 on a plane parallel to the Y-axis direction and the Z-axis direction. Each of the lower coil elements 106 is reconfigured. Further, the cross-sectional image range indicated by the tomographic image data is a range including the upper coil element 105 at least in the Z-axis direction, as shown in FIG. Further, this processing can shorten the time by making the resolution of the image data coarse.

  For example, an example of the image indicated by the reconstructed image data is shown in FIG. For example, FIG. 12A shows an image represented by image data obtained by the magnetic resonance signal obtained by the upper coil element 105, and FIG. 12B shows an image obtained by the magnetic resonance signal obtained by the lower coil element 106. The image which data shows is shown. The image of the reconstructed image data becomes a similar image in this way.

  Next, the control / calculation unit 31 receives the magnetic resonance received by the upper coil element 105 and the lower coil element 106 in the lines indicated by A and B in FIGS. 12A and 12B, for example, near the center of each image data. The intensity of the signal (hereinafter sometimes referred to as signal intensity) is measured. The measurement results are shown in FIG. FIG. 13 is a graph showing the sensitivity distribution as the signal intensity measured on the vertical axis and the position on the Z axis along the horizontal axis. In such a coil element, since the signal intensity at the center of the coil (see FIG. 6B) is high, a high signal intensity appears in the center position of the coil array in the sensitivity distribution in the coil array arrangement direction.

  For example, if the upper coil element 105 and the lower coil element 106 are shifted by a shift amount as shown in FIG. 11 (b), the upper coil element 105 and the lower coil element 105 may be shifted as the peak shift amount of the sensitivity distributions A and B. The amount of deviation of the coil element 106 appears. Accordingly, the control / calculation unit 31 compares the sensitivity distributions to obtain the deviation amount of the peak of A and B and the pitch of the peak of either A or B, and the ratio between the deviation amount of the peak and the pitch of the peak and The amount of deviation between the upper coil element 105 and the lower coil element 106 can be obtained as the length from the length of the coil array pitch. The pitch length of the coil array may be stored in advance in the storage means 34, for example.

  Then, the control / calculation unit 31 displays the length of the obtained shift amount on the display unit 33, for example. However, it is not limited to the provision to the operator by display on the display unit 33.

(Mode of operation)
Next, information provision according to the second embodiment will be described with reference to FIG. FIG. 14 is a flowchart illustrating a procedure for providing information according to the second embodiment.

  The information provision as described above will be described as being performed in the pre-scan. The pre-scan is a process for optimizing each parameter in order to perform a main scan for collecting data for actually obtaining an MRI image under an optimal condition. Typical examples include resonance frequency detection, RF transmission power optimization, and reception gain optimization. In addition, the pitch length of the coil row of the upper coil element 105 is stored in advance.

  When a pre-scan execution instruction is input from the operation unit 32 (step S101; hereinafter, step S100 is omitted and displayed as S100. Other steps are similarly omitted and displayed), the control / calculation unit 31. Controls each unit and performs pre-scanning (S102).

  Then, the control / calculation unit 31 acquires the digital data of the magnetic resonance signals received by the upper coil element 105 and the lower coil element 106 via the RF coil connector board 110 and the receiver 205, For each of the lower coil elements 106, image data of the sagittal section is reconstructed (S103).

  Next, the control / calculation unit 31 measures the signal intensity, for example, near the center (see FIGS. 12A and 12B) of each image data, and acquires the sensitivity distribution (S104). Then, the control / calculation unit 31 compares the sensitivity distribution for each of the upper coil element 105 and the lower coil element 106, and compares the ratio between the peak shift amount and the peak pitch and the coil of the upper coil element 105 stored in advance. The shift amount is obtained as a length from the length of the pitch of the row, and is displayed on the display unit 33 (S105).

  As described above, by comparing the sensitivity distributions of the upper coil element 105 and the lower coil element 106, the amount of deviation between the upper coil element 105 and the lower coil element 106 is obtained, and displayed on the display means, for example. It is possible to provide the amount of deviation obtained by the above. Therefore, it is possible to collect an optimal image by moving the upper coil element 105 based on the amount of deviation and correcting the position.

It is an external view of the MRI apparatus which concerns on this Embodiment. It is a schematic sectional drawing for demonstrating the structure of a bed part and a magnetic field generator. It is a perspective view which shows the closed state of the capsule type coil unit concerning this invention. It is sectional drawing of the capsule cover of a capsule type coil unit. It is an enlarged view of a rail part. It is a figure for demonstrating the structure of an upper coil part. It is a perspective view which shows the open state of the capsule type coil unit concerning this invention. It is a figure which shows the structure inside a capsule bed part. It is a block diagram which shows the control structure of the MRI apparatus of this Embodiment. It is a block diagram which shows the connection structure of a capsule type coil unit. It is a figure for demonstrating the cross section of the image reconfigure | reconstructed by a control and calculating part. It is a figure which shows an example of the image which the reconfigure | reconstructed image data shows. It is a graph which shows a sensitivity distribution as a signal intensity | strength which measured the vertical axis | shaft and the position on the Z-axis each horizontal axis. It is a flowchart which shows the procedure of the information provision which concerns on 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bed part 2 Magnetic field generator 3 Console 4 Capsule-type coil unit 11 Top plate part 12 Rail part 13 Lifting part 21 Opening part 31 Control / calculation part 32 Operation part 33 Display part 34 Storage means 40 Capsule lid 41 Upper coil part 42 Rail Part 43 Upper coil part end part 44 Hinge mechanism 45 Lock part 50 Capsule bed part 51 Mat 52 Concave part 53 Belt A
54 Belt B
55 Air Duct A
56 Air duct B
57 Packing 58 Lower coil part 59 Base 80 Lifting mechanism part 81 Post 82 Idle gear A
83 Gear B
84 Idle Gear B
85 Nut 86 Dial 101 Gradient magnetic field coil 102 Static magnetic field magnet 103 Shim coil 104 Transmitting coil 105 Upper coil element 106 Lower coil element 110 RF coil connector board 120 Air control unit 121 Air tube 122 Body cable 124 Connection board (lid)
125 Connection board (main unit)
126 Lid cable 131 Top plate part raising / lowering mechanism driving means 132 Top plate part moving mechanism driving means 201 Gradient magnetic field power supply 203 Shim coil power supply 204 Transmitter 205 Receiver

Claims (12)

A coil unit used in a magnetic resonance imaging apparatus for reconstructing an image based on a magnetic resonance signal emitted from a subject in a static magnetic field to which a gradient magnetic field is applied,
A bed having an upper table for lying down on the subject, and a lower coil element disposed along the upper table on the lower side of the upper table and receiving a magnetic resonance signal emitted from the subject When,
A coil unit characterized in that a lid capable of covering and sealing the subject is provided on the upper side of the bed.   The coil unit according to claim 1, wherein the lid is in contact with the bed with a packing interposed therebetween.   The coil unit according to claim 1, wherein the upper top plate has a concave-shaped portion that accommodates the subject on a surface for lying the subject.   The coil unit according to any one of claims 1 to 3, wherein the upper top plate is formed of a mat.   The coil unit according to any one of claims 1 to 4, further comprising means for fixing the subject to the upper top plate.   The coil unit according to any one of claims 1 to 5, wherein the lid is detachably or detachably attached to the bed.   The coil unit according to any one of claims 1 to 6, wherein the lid is made of a transparent member in whole or in part.   The upper coil element for receiving a magnetic resonance signal radiated from the subject provided on the upper side of the lid so as to be movable in the body axis direction of the subject. Coil unit.   The coil unit according to claim 8, wherein each of the lower coil element and the upper coil element includes a plurality of coils, and the number of coils of the upper coil element is smaller than that of the lower coil element.   The bed includes a base that holds the lower coil element below the upper top plate along the upper top plate, and the base is moved up and down to increase the distance between the subject and the upper coil element. The coil unit according to claim 8 or 9, further comprising an elevating mechanism for adjusting. An air duct for intake and exhaust of the air inside the bed;
The coil unit according to any one of claims 1 to 10, further comprising an air tube connected to the air duct and extending to at least the outside of the static magnetic field. An image based on a magnetic resonance signal radiated from a subject in a static magnetic field having a cylindrical opening and having a first bed that can be inserted into and removed from the opening and to which a gradient magnetic field in the opening is applied. A magnetic resonance imaging apparatus for reconstructing
A bed having an upper table for lying down on the subject, and a lower coil element disposed along the upper table on the lower side of the upper table and receiving a magnetic resonance signal emitted from the subject A lid that covers and covers the subject on the upper side of the bed, and is movable in the body axis direction of the subject along the upper side of the lid, and has fewer coils than the lower coil element. An upper coil element that receives a magnetic resonance signal radiated from the subject that includes a plurality of coils, and a coil unit that is placed on the first bed,
Information providing means for measuring the distribution of the intensity of magnetic resonance signals received by the upper coil element and the lower coil element and providing information indicating the position of the upper coil element with respect to the lower coil element based on the distribution of the intensity A magnetic resonance imaging apparatus comprising:

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