Magnetic Resonance Imaging System

Abstract

To minimize the discomfort experienced by the subject during imaging. [Solution] The magnetic resonance imaging apparatus of the embodiment comprises an MR image acquisition unit, a subject fixation device, and a control unit. The MR image acquisition unit includes a bed on which a subject is placed and acquires an MR image of the subject. The subject fixation device fixes the subject to a bed that is fixed relative to the MR image acquisition unit. The control unit controls the fixing and release of the subject by the subject fixation device in accordance with the progress of the MR image acquisition process by the MR image acquisition unit.

Description

Technical Field

[0001] The embodiments disclosed in this specification and the drawings relate to magnetic resonance imaging devices.

Background Art

[0002] When a subject such as a patient moves during an examination by a magnetic resonance imaging (MRI) device, problems such as poor scanning and transmission and reception of nuclear magnetic resonance signals during imaging processing may occur, leading to a deterioration in image quality. To avoid such problems, for example, a subject fixing device is used to fix the subject to a bed so that the subject does not move during imaging processing.

[0003] However, if the subject is fixed to the bed for a long time, it will impose mental and physical pain on the subject. To reduce such pain of the subject, if the fixation by the subject fixing device is loosened, the subject or the RF coil during imaging processing may move, leading to a deterioration in image quality, or even re-imaging.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The problem to be solved by the embodiments disclosed in this specification and the drawings is to reduce the pain of the subject during imaging processing. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problems. The problems corresponding to the respective effects of each configuration shown in the embodiments described later can also be regarded as other problems.

Means for Solving the Problems

[0006] The magnetic resonance imaging apparatus of this embodiment comprises an MR image acquisition unit, a subject fixation device, and a control unit. The MR image acquisition unit includes a bed on which a subject is placed and acquires MR images of the subject. The subject fixation device fixes the subject to a bed that is fixed relative to the MR image acquisition unit. The control unit controls the fixing and release of the subject by the subject fixation device in accordance with the progress of the MR image acquisition process by the MR image acquisition unit. [Brief explanation of the drawing]

[0007] [Figure 1] A block diagram showing the overall configuration of the MRI apparatus 1 according to the first embodiment. [Figure 2] An example of a configuration for controlling the fixation device 100 in the MRI device 1 will be described. [Figure 3] Cross-sectional view of an example of fastener 100. [Figure 4] A flowchart showing an example of the processing performed by MRI device 1. [Figure 5] This figure illustrates an example of a configuration for controlling the fixing device 200 in an MRI apparatus of the second embodiment. [Figure 6] A diagram showing an example of a cross-section of the fixing device 300 in the MRI apparatus of the third embodiment. [Modes for carrying out the invention]

[0008] The magnetic resonance imaging apparatus of this embodiment will be described below with reference to the drawings.

[0009] (First Embodiment) Figure 1 is a block diagram showing the overall configuration of the MRI apparatus 1 according to the first embodiment. As shown in Figure 1, the MRI apparatus 1 comprises a gantry 21, a patient table 32, a tabletop 34, a fixing device 100, and a fixing drive unit 110. The patient table 32 supports the patient. Of the gantry 21 (including the devices inside the gantry 21), the patient table 32, the tabletop 34, and the control side configuration described later, at least the configuration that controls these is an example of an MR image acquisition unit that captures MR images of the patient.

[0010] The top plate 34 is movably positioned on the bed 32 so as to be supported by the bed 32. The MRI apparatus 1 also includes, for example, a static magnetic field magnet 22, a shim coil 24, a gradient magnetic field coil 26, a transmitting RF coil 28, a receiving RF coil, and an RF coil device 30, all located within a gantry 21 that is formed in a cylindrical shape. The gantry 21 corresponds to the part shown by the thick outline in the figure.

[0011] The subject P is placed on the top plate 34. The static magnetic field magnet 22 and the shim coil 24 are, for example, cylindrical in shape, and the shim coil 24 is positioned inside the static magnetic field magnet 22 with the same axis as the static magnetic field magnet 22. Here, as an example, the mutually orthogonal X, Y, and Z axes of the device coordinate system are defined as follows.

[0012] First, the static magnetic field magnet 22 and the shim coil 24 are arranged so that their axial directions are perpendicular to the vertical direction, and the axial direction of the static magnetic field magnet 22 and the shim coil 24 is the Z-axis direction. Also, the vertical direction is defined as the Y-axis direction, and the top plate 34 is arranged so that the direction of the normal to its mounting surface is the Y-axis direction.

[0013] The MRI apparatus 1 includes, as its control side, a static magnetic field power supply 40, a shim coil power supply 42, a gradient magnetic field power supply 44, an RF transmitter 46, an RF receiver 48, a tabletop drive device 50, a system control unit 52, a system bus 54, an image reconstruction unit 56, an image database 58, an image processing unit 60, an input device 62, a display device 64, and a storage device 66. The tabletop drive device 50 is located inside the patient table 32.

[0014] The RF coil device 30 is positioned near the subject. The installation position of the RF coil device 30 is set to an appropriate position according to the imaging area of ​​the subject. The connector of the RF coil device is connected to the connection port 36 of the top plate 34. Through the connection port 36, identification information of the RF coil device 30 is input to the system control unit 52 via wiring within the MRI device 1.

[0015] The static magnetic field magnet 22 forms a static magnetic field in the imaging space by the current supplied from the static magnetic field power supply 40. The imaging space refers to, for example, the space within the gantry 21 where the subject P is placed and the static magnetic field is applied. The static magnetic field magnet 22 is often composed of a superconducting coil, and is connected to the static magnetic field power supply 40 to supply current when excited, but is generally left disconnected after being excited. The static magnetic field magnet 22 may be made of a permanent magnet without providing the static magnetic field power supply 40.

[0016] The shim coil 24 is connected to the shim coil power supply 42, and the static magnetic field is made uniform by the current supplied from the shim coil power supply 42. The gradient magnetic field coil 26 is formed in a cylindrical shape inside the static magnetic field magnet 22, for example. The gradient magnetic field coil 26 forms gradient magnetic fields Gx in the X-axis direction, Gy in the Y-axis direction, and Gz in the Z-axis direction in the imaging region, respectively, by the current supplied from the gradient magnetic field power supply 44. That is, the gradient magnetic fields Gx, Gy, and Gz in the three axes of the device coordinate system are combined, and the slice selection direction gradient magnetic field Gss, the phase encoding direction gradient magnetic field Gpe, and the readout direction (frequency encoding direction) gradient magnetic field Gro can be arbitrarily set as logical axes.

[0017] The RF transmitter 46 generates an RF pulse (RF current pulse) at the Larmor frequency to induce nuclear magnetic resonance based on control information input from the system control unit 52, and transmits it to the transmitting RF coil 28. The transmitting RF coil 28 receives the RF pulse from the RF transmitter 46 and transmits this RF pulse to the subject P. The transmitting RF coil 28 includes a whole-body coil (not shown) that is built into the gantry 21 and is used for both transmitting and receiving RF pulses.

[0018] Inside the top plate 34, a receiving RF coil 29 is arranged. The receiving RF coil 29 detects a nuclear magnetic resonance signal (hereinafter referred to as an MR signal) generated when the nuclear spins in the subject P are excited by an RF pulse, and transmits the detected MR signal to the RF receiver 48. The RF receiver 48 performs predetermined signal processing on the detected MR signal to generate complex data of the digitized MR signal (hereinafter referred to as raw data of the MR signal). The RF receiver 48 inputs the raw data of the MR signal to the image reconstruction unit 56.

[0019] The system control unit 52 performs system control of the entire MRI apparatus 1 via wirings such as the system bus 54 during the imaging operation and the image display after imaging. For this purpose, the system control unit 52 stores control information necessary for driving the gradient magnetic field power supply 44, the RF transmitter 46, and the RF receiver 48. The control information here is, for example, sequence information describing operation control information such as the intensity, application time, and application timing of the pulse current applied to the gradient magnetic field power supply 44.

[0020] The system control unit 52 realizes various functions by, for example, a hardware processor executing a program stored in a memory device (memory circuit). The hardware processor means, for example, a circuit such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an application specific integrated circuit (ASIC), a programmable logic device (for example, a simple programmable logic device (SPLD) or a complex programmable logic device (CPLD), a field programmable gate array (FPGA)). Instead of storing the program in the memory device 66, it may be configured to directly incorporate the program into the circuit of the hardware processor. In this case, the hardware processor realizes functions by reading and executing the program incorporated in the circuit. The hardware processor is not limited to being configured as a single circuit, and may be configured as one hardware processor by combining a plurality of independent circuits to realize each function. Also, a plurality of components may be integrated into one hardware processor to realize each function.

[0021] The system control unit 52 generates gradient magnetic fields Gx, Gy, Gz and RF pulses by driving the gradient magnetic field power supply 44, the RF transmitter 46, and the RF receiver 48 according to a stored predetermined sequence. The system control unit 52 controls the top plate driving device 50 to move the top plate 34 in the Z-axis direction and move the top plate 34 in and out of the imaging space inside the gantry 21. By thus controlling the position of the top plate 34, the system control unit 52 positions the imaging site of the subject P on the top plate 34 at the magnetic field center in the imaging space.

[0022] The system control unit 52 also functions as an imaging condition setting unit. Based on the subject P information and some imaging conditions entered by the operator into the input device 62, the system control unit 52 sets the imaging conditions for this scan. To this end, the system control unit 52 displays the imaging condition setting screen information on the display device 64. The input device 62 provides the operator with the function to set imaging conditions and image processing conditions.

[0023] In this specification, the input device 62 is not limited to those equipped with physical operating components such as a mouse or keyboard. For example, an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device provided separately from the device and outputs this electrical signal to a control circuit is also included as an example of an input device 62.

[0024] Imaging conditions refer to, for example, the type of pulse sequence used, the conditions under which RF pulses are transmitted, and the conditions under which MR signals are collected from the subject P. Examples of imaging conditions include the imaging area and imaging site as positional information within the imaging space, the type of pulse sequence such as parallel imaging, the type of RF coil device 30 used, the number of slices, and the interval between slices.

[0025] The imaging area refers to which part of the subject P, such as the head, chest, or abdomen, will be imaged as the imaging region. "Main scan" refers to the scan for acquiring the desired diagnostic image, such as a proton density-weighted image, and does not include scans for acquiring MR signals for positioning images or calibration scans. "Scan" refers to the MR signal acquisition operation and does not include image reconstruction. A calibration scan refers to a scan performed separately from the main scan, for example, to determine undetermined imaging conditions for the main scan or conditions and data to be used during image reconstruction after the main scan.

[0026] The image reconstruction unit 56 converts the raw data of the MR signal input from the RF receiver 48 into, for example, matrix data based on the number of phase encoding steps and the number of frequency encoding steps, and stores this as k-space data. k-space refers to the frequency space (Fourier space). The image reconstruction unit 56 generates image data of the subject P by applying image reconstruction processing, including a two-dimensional Fourier transform, to the k-space data. The image reconstruction unit 56 stores the generated image data in the image database 58.

[0027] The image processing unit 60 retrieves image data from the image database 58, performs predetermined image processing on it, and stores the processed image data in the storage device 66 as display image data. The storage device 66 stores the above-mentioned display image data along with supplementary information such as the imaging conditions used to generate the display image data and information about the subject P (subject information).

[0028] The display device 64 displays, in accordance with the control of the system control unit 52, a screen for setting the imaging conditions for this scan, and images shown by the image data generated by the imaging. The following describes the operation flow when performing imaging including the head in the imaging area using the MRI device 1.

[0029] The RF coil device 30 is mounted on the top plate 34 at an appropriate position on the subject P. The top plate drive device 50 then moves the top plate 34 on which the subject P is placed so that the head, which is the imaging area, is positioned at the center of the magnetic field within the gantry 21. A static magnetic field is then formed in the imaging space by the static magnetic field magnet 22, which is excited by the static magnetic field power supply 40. Additionally, current is supplied to the shim coil 24 from the shim coil power supply 42 to homogenize the static magnetic field formed in the imaging space.

[0030] Then, when an imaging start instruction is input from the input device 62 to the system control unit 52, the system control unit 52 drives the gradient magnetic field power supply 44, RF transmitter 46, and RF receiver 48 according to the pulse sequence defined by the imaging conditions of this scan, thereby forming a gradient magnetic field in the imaging area and generating RF pulses from the transmitting RF coil 28.

[0031] Therefore, the MR signal generated by nuclear magnetic resonance inside the subject P is received by the RF coil device 30 and the receiving RF coil 29, and detected by the RF receiver 48. The RF receiver 48 generates raw MR signal data by applying predetermined signal processing to the detected MR signal. The RF receiver 48 inputs the raw MR signal data to the image reconstruction unit 56.

[0032] The image reconstruction unit 56 converts the raw MR signal data into, for example, matrix data based on the number of phase encoding steps and the number of frequency encoding steps, and stores this as k-space data. In this way, the MR signal is collected by this scan and stored as k-space data. The image reconstruction unit 56 reconstructs the image data of subject P by applying an image reconstruction process including a Fourier transform to the k-space data, and stores this in the image database 58.

[0033] The image processing unit 60 obtains the reconstructed image data from the image database 58, applies predetermined image processing to it to generate display image data, and stores this display image data in the storage device 66. The system control unit 52 displays the image indicated by the display image data on the display device 64.

[0034] Figure 2 is a diagram illustrating an example of a configuration for controlling the fixation device 100 in the MRI apparatus 1. During imaging processing, including scanning, in the MRI apparatus 1, the subject P is fixed to the tabletop 34 of the patient bed 32 by the fixation device 100, relative to the MR image acquisition unit including the gantry 21. The fixation device 100 is an example of a subject fixation device. Figure 3 is a cross-sectional view of an example of the fixation device 100. The fixation device 100 includes, for example, a vacuum fixation device 102 and a cooling device 104. The fixation drive unit 110 includes a vacuum pump 112 and a blower fan 114.

[0035] The vacuum fixing device 102 is connected to the vacuum pump 112. The vacuum pump 112 creates a vacuum around the vacuum fixing device 102. The vacuum fixing device 102 contracts due to the vacuum created by the vacuum pump 112, fixing the subject P in place, and releases the subject P from being fixed when the vacuum is released. The vacuum pump 112 creates a vacuum around the vacuum fixing device 102, causing it to contract and fixing the subject P to the top plate 34. The vacuum pump 112 releases the subject P fixed to the top plate 34 by releasing the vacuum around the vacuum fixing device 102.

[0036] The cooling device 104 is positioned between the fixing device 100 and the subject P. The cooling device 104 includes, for example, a blower into which cooling air can flow. The cooling device 104 is connected to a blower fan 114. The blower fan 114 supplies or stops supplying cooling air to the cooling device 104. The fixing device 100 may be provided on the RF coil device 30. For example, if the RF coil device 30 is a body coil or arm coil attached to the subject P, the fixing device 100 may be provided on the part of the RF coil device 30 located between the coil portion and the subject P.

[0037] The blower fan 114 supplies cooling air to the cooler 104, causing the cooling air to circulate within the cooler 104. The cooler 104 cools the subject P, which is fixed to the top plate 34, with the circulating cooling air. The blower fan 114 stops supplying cooling air to the cooler 104, thereby ending the cooling of the subject P.

[0038] The system control unit 52 controls the fixing and release of the subject P by the fixing device 100 in accordance with the progress of the MR image acquisition process by the MR image acquisition unit. Based on the start instruction signal transmitted by the input device 62, the system control unit 52 starts the imaging process by the MRI device 1. When starting the imaging process by the MRI device 1, the system control unit 52 transmits an imaging start signal to the RF transmitter 46 and RF receiver 48, and controls the vacuum pump 112 in the fixing drive unit 110 to control the fixing and release of the subject P by the vacuum fixing device 102. The system control unit 52 is an example of a control unit.

[0039] A thermometer 106 and a pressure sensor 108 are provided inside the fixing device 100. The thermometer 106 measures the body temperature of the subject P during imaging processing by the MRI device 1. The thermometer 106 transmits the subject's body temperature obtained as a measurement result to the system control unit 52. Based on the body temperature transmitted by the thermometer 106, the system control unit 52 controls the cooling state of the subject P by the cooling device 104.

[0040] The system control unit 52 controls the cooling state of the subject P by the cooling device 104 by, for example, instructing the blower fan 114 in the fixed drive unit 110 to supply or stop supplying cooling air to the cooling device 104 based on the subject's body temperature transmitted by the thermometer 106. The thermometer is an example of a temperature sensor.

[0041] As shown in Figure 3, the pressure sensor 108 is positioned between the fixing device 100 and the subject P. The pressure sensor 108 measures the pressure applied to the subject P, which is fixed by the vacuumed fixing device 100. The pressure sensor 108 transmits the measured pressure as a measurement result to the system control unit 52.

[0042] The system control unit 52 controls the fixing strength to the subject P by adjusting the vacuum strength applied to the vacuum fixing device 102 based on the pressure measured by the pressure sensor 108. For example, if the pressure measured by the pressure sensor 108 exceeds a predetermined threshold, the system control unit 52 may reduce the vacuum strength or release the vacuum.

[0043] Next, the processing in MRI device 1 will be explained. Figure 4 is a flowchart showing an example of the processing in MRI device 1. Figure 4 illustrates the procedure for imaging a subject using MRI device 1. In MRI device 1, first, a fixation device 100 is attached to the subject P to be examined (step S101), and the subject P is placed on the tabletop 34 of the bed 32. At this stage, the vacuum fixation device 102 attached to the subject P has not yet been vacuumed by the vacuum pump 112, and the subject is not yet fixed by the fixation device 100.

[0044] Next, for example, when a technician operating the MRI device 1 operates the input device 62, the system control unit 52 receives a start instruction signal, and the patient table 32 is inserted into the gantry 21 and positioned at the imaging position, and the imaging process by the MRI device 1 begins (step S103). Once the patient table 32 is positioned at the imaging position, or has been moved to the imaging position and the imaging process has begun, the system control unit 52 turns on the vacuum pump 112, uses the vacuum pump 112 to evacuate the vacuum fixing device 102, and uses the vacuum fixing device 102 to fix the subject P to the top plate 34 of the patient table 32 (step S105). The imaging process may also begin before the patient table 32 is inserted into the gantry 21.

[0045] Once the subject P is fixed to the tabletop 34 of the bed 32, imaging processing such as scanning the subject P is performed by the MR imaging unit including the gantry 21. While the imaging processing of the subject P is being performed, the thermometer 106 measures the subject P's body temperature and transmits it to the system control unit 52. The system control unit 52 determines whether or not the subject P's body temperature is high (step S107).

[0046] The system control unit 52, for example, refers to a threshold for determining that the subject P's body temperature is high, and determines that the subject P has a high temperature if the subject P's body temperature exceeds the threshold. If the system control unit 52 determines that the subject P has a high temperature, it turns on the blower fan 114 if it is OFF (step S109) and supplies cooling air to the cooling device 104 to cool the subject P. If the blower fan 114 is ON, it maintains that state.

[0047] If the system control unit 52 determines that the subject P is not at a high temperature, it turns off the blower fan 114 if it is ON (step S111), and maintains the state if the blower fan 114 is OFF. Subsequently, the system control unit 52 determines whether the pressure transmitted by the pressure sensor 108 exceeds a predetermined threshold (step S113).

[0048] If the pressure transmitted by the pressure sensor 108 is determined to exceed a predetermined threshold, the system control unit 52 reduces the strength of the vacuum pump 112 (step S115) to decrease the force holding the subject P in place. If the pressure transmitted by the pressure sensor 108 is determined not to exceed a predetermined threshold, the system control unit 52 skips the process in step S115.

[0049] Next, the system control unit 52 determines whether the imaging process is complete or not (step S117). If it determines that the imaging process is not complete, the system control unit 52 returns to step S107. If it determines that the imaging process is complete, the system control unit 52 turns off the vacuum pump 112 and releases the vacuum from the vacuum fixing device 102 (step S119), thereby releasing the subject P from the fixation.

[0050] At this time, if the blower fan 114 is ON, the system control unit 52 turns the blower fan 114 OFF. Next, the patient table 32 is discharged from the gantry 21, and the fixing device 100 attached to the subject P is removed from the subject P (step S121). In this way, the MRI device 1 completes the process shown in Figure 4.

[0051] The MRI apparatus 1 of the first embodiment includes a fixing device 100 that secures the subject P to the tabletop 34 by creating a vacuum using a vacuum pump 112. Therefore, the system control unit 52 can operate the vacuum pump 112 to create a vacuum in the vacuum fixing device 102 of the fixing device 100, thereby securing the subject P to the tabletop 34. For example, the subject P can be secured to the tabletop 34 at a necessary timing during the imaging process by the MRI apparatus 1. Consequently, even if the subject P is left free and not secured at other times, problems caused by the subject P moving can be suppressed. Thus, the discomfort of the subject during the imaging process can be reduced.

[0052] (Second embodiment) Next, a second embodiment will be described. The MRI apparatus of the second embodiment differs from that of the first embodiment mainly in the configuration of the fixing device. The MRI apparatus of the second embodiment will be described below, focusing on the differences from the first embodiment. Figure 5 is a diagram illustrating an example of a configuration for controlling the fixing device 200 in the MRI apparatus of the second embodiment.

[0053] In the MRI apparatus of the second embodiment, the fixation device 200 comprises a plurality of element fixation devices, for example, a first element fixation device 200A, a second element fixation device 200B, and a third element fixation device 200C. The first element fixation device 200A is positioned around the chest of the subject P, the second element fixation device 200B is positioned around the torso of the subject P, and the third element fixation device 200C is positioned around the chest of the subject P. The first element fixation device 200A, the second element fixation device 200B, and the third element fixation device 200C are examples of elements.

[0054] The first element fixing devices 200A to the third element fixing devices 200C are all equipped with vacuum fixing devices and coolers similar to those of the fixing device 100 in the first embodiment. A vacuum pump 112 is connected to the vacuum fixing device of each of the first element fixing devices 200A to the third element fixing devices 200C. A blower fan 114 is connected to the cooler of each of the first element fixing devices 200A to the third element fixing devices 200C.

[0055] The system control unit 52 can individually control the vacuum fixtures of the first element fixtures 200A to the third element fixtures 200C by using the vacuum pump 112 to evacuate or release the vacuum. The system control unit 52 can also individually control the supply of cooling air to each of the coolers of the first element fixtures 200A to the third element fixtures 200C. Other aspects, such as configuration, are the same as in the first embodiment.

[0056] In the MRI apparatus of the second embodiment, the system control unit 52 controls the vacuum pump 112 to evacuate the vacuum fixtures of the first element fixture 200A to the third element fixture 200C, thereby fixing the subject P in an appropriate position. For example, by evacuating the vacuum fixture of the first element fixture 200A, the chest of the subject P is fixed by the vacuum fixture.

[0057] The MRI apparatus of the second embodiment provides the same effects and advantages as the MRI apparatus of the first embodiment. Furthermore, in the MRI apparatus of the second embodiment, it is appropriate to fix the subject P in an appropriate position depending on the subject P's body shape and the area being imaged. Here, since each of the vacuum fixing devices of the first element fixing device 200A to the third element fixing device 200C can be vacuumed independently, the subject P can be fixed in an appropriate position on the tabletop 34 of the bed 32.

[0058] Furthermore, the system control unit 52 controls the blower fan 114 to supply cooling air to the cooling devices of the first element fixing device 200A to the third element fixing device 200C, thereby cooling appropriate locations on the subject P. For example, by supplying cooling air to the cooling device of the first element fixing device 200A, the chest area of ​​the subject P can be cooled. This ensures that appropriate locations are cooled when cooling the subject P.

[0059] (Third embodiment) Next, a third embodiment will be described. Figure 6 shows an example of a cross-section of the fixing device 300 in the MRI apparatus of the third embodiment. The fixing device 300 includes a belt-type fixing device 302 instead of the vacuum fixing device 102 of the first embodiment. A winding machine 116 is connected to one end of the belt-type fixing device 302. The system control unit 52 can control the winding machine 116 instead of the vacuum pump 112 of the first embodiment. A cooling device 104 similar to that of the first embodiment is provided between the belt-type fixing device 302 and the subject P. Other points are common with the first embodiment in terms of configuration, etc.

[0060] In the MRI apparatus of the third embodiment, the system control unit 52 controls the winding machine 116 to pull the belt-type fastener 302, thereby fixing the subject P to the top plate 34 of the bed 32 with the belt-type fastener 302. A cooling device is placed between the belt-type fastener 302 and the subject P.

[0061] The MRI apparatus of the third embodiment provides the same effects and advantages as the MRI apparatus of the first embodiment. In addition, in the MRI apparatus of the third embodiment, the subject P is fixed to the tabletop 34 by the belt-type fixing device 302 when the winding machine 116 is wound up. Since the belt-type fixing device 302 can be wound up by the winding machine 116 and the subject P can be fixed to the tabletop 34, the subject P can be quickly fixed to the tabletop 34.

[0062] Furthermore, the system control unit 52 controls the blower fan 114 to supply cooling air to the cooling device. Since the cooling device is positioned between the belt-type fixing device 302 and the subject P, the subject P can be properly cooled by supplying cooling air to the cooling device.

[0063] In the first embodiment described above, a pressure sensor is placed between the fixing device 100 and the subject P to measure the pressure applied to the subject P by the fixing device 100. The system control unit 52 may adjust the strength of the vacuum applied to the vacuum fixing device 102 based on the results of the pressure sensor to control the fixing strength to the subject P. For example, if the pressure measured by the pressure sensor exceeds a predetermined threshold, the strength of the vacuum may be reduced or the vacuum may be released.

[0064] According to at least one embodiment described above, the magnetic resonance imaging apparatus includes a bed on which a subject is placed, an MR image acquisition unit that captures an MR image of the subject, a subject fixing device that fixes the subject to the bed relative to the MR image acquisition unit, and a control unit that controls the fixing and release of the subject by the subject fixing device in accordance with the progress of the MR image acquisition process by the MR image acquisition unit, thereby reducing the discomfort of the subject during the imaging process.

[0065] While several embodiments have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of Symbols]

[0066] 1 MRI machine 21 Gantry 22 Static magnetic field magnet 24 Shim Coil 26. Gradient Coils 28 RF coil for transmission 29. Receiver RF coil 30 RF coil device 32 berths 34 Top plate 36 connection ports 40 Static magnetic field power supply 42 Shim coil power supply 44 Gradient magnetic field power supply 46 RF transmitter 48 RF Receiver 50 Top plate drive mechanism 52 System Control Unit 54 System bus 56 Image reconstruction unit 58 Image Databases 60 Image Processing Unit 62 Input devices 64 Display device 66 Storage device 100 Fixtures 102 Vacuum fixture 104 Cooling devices 106 Thermometer 108 Pressure Sensor 110 Fixed drive unit 112 Vacuum pump 114 Blower fan 116 Winding machine 200 Fixtures 200A First element fixing device 200B Second Element Fixing Device 200C Third Element Fixing Device 300 Fixtures 302 Belt-type fastener P Subject

Claims

1. The system includes a bed on which a subject is placed, and an MR image acquisition unit that captures an MR image of the subject, A subject fixing device for fixing the subject to a bed that fixes the subject relative to the MR image acquisition unit, The system includes a control unit that controls the fixing and release of the subject by the subject fixing device in accordance with the progress of the MR image acquisition process by the MR image acquisition unit, Magnetic resonance imaging device.

2. The subject fixing device includes a vacuum fixing device that contracts under vacuum to fix the subject, The system further comprises a vacuum pump for performing vacuum evacuation on the aforementioned vacuum fixing device, The control unit controls the vacuum pump. The magnetic resonance imaging apparatus according to claim 1.

3. The subject fixation device includes a plurality of elements, The control unit controls the fixing and release of the subject for each of the multiple elements. The magnetic resonance imaging apparatus according to claim 1.

4. Equipped with a winding machine for winding up belt-type fasteners, The subject fixing device includes the belt-type fixing device which fixes the subject by being wound up by the winding machine, The control unit controls the winding machine. The magnetic resonance imaging apparatus according to claim 1.

5. A temperature sensor for measuring the body temperature of the subject, The following further comprises a cooling device for cooling the subject: The control unit controls the cooling state of the subject by the cooling device based on the measurement results of the temperature sensor. The magnetic resonance imaging apparatus according to claim 1.

6. The cooling device is positioned between the subject fixing device and the subject and includes a blower into which cooling air can flow. The control unit controls the blower fan that supplies the cooling air to the blower unit. The magnetic resonance imaging apparatus according to claim 5.

7. The device further includes a pressure sensor for measuring the pressure applied to the subject by the subject fixing device, The control unit controls the fixing strength to the subject based on the results of the pressure sensor. The magnetic resonance imaging apparatus according to claim 1.

8. The MR image acquisition unit is equipped with an RF coil for detecting nuclear magnetic resonance signals. The subject fixation device is provided on the RF coil, The magnetic resonance imaging apparatus according to claim 1.

9. The control unit, when starting the imaging process, fixes the subject, The magnetic resonance imaging apparatus according to claim 1.

10. When the imaging process is completed, the control unit releases the subject from the fixation. The magnetic resonance imaging apparatus according to claim 1.

Images