Magnetic resonance imaging system

Abstract

To increase the accuracy of imaging synchronization control with a main device in a wireless coil device.SOLUTION: A magnetic resonance imaging system according to one embodiment includes a main device and a coil device separate from the main device. The main device includes a first timer that operates with a synchronous clock. The coil device includes a clock reproducing unit, a second timer, and a detection unit. The clock reproducing unit regenerates the synchronous clock from a first radio signal transmitted by the main device. The second timer operates with the synchronous clock. The detection unit detects timing of receiving a second radio signal transmitted by the main device. The magnetic resonance imaging device performs a synchronized imaging operation by correcting at least one of the first timer included in the main device and the second timer included in the coil device, according to the timing.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The embodiments disclosed in this specification and in the drawings relate to a magnetic resonance imaging apparatus. [Background technology]

[0002] A magnetic resonance imaging (MRI) device is an imaging device that excites the nuclear spins of a subject placed in a static magnetic field with an RF (Radio Frequency) pulse signal at the Larmor frequency, and generates an image by reconstructing the magnetic resonance (MR) signals generated from the subject in response to the excitation.

[0003] In an MRI device, an RF pulse is transmitted from the main unit to the subject. The MR signal emitted from the subject in response to this transmission is received by the coil unit. The coil unit receives the MR signal emitted from the subject at a position close to the subject. There are various types of coil units depending on the part of the subject to be imaged, such as for the head, chest, spine, and lower limbs.

[0004] Conventionally, wired coil units that transmit received MR signals to a main unit via wires have been widely used. In contrast, wireless coil units have been proposed that convert received MR signals from analog to digital signals using an ADC (Analog to Digital Converter) and transmit the digitized MR signals wirelessly to the main unit.

[0005] When using a wired coil unit, the imaging operations of the main unit and the coil unit are controlled according to a set time schedule (hereinafter, referred to as a pulse sequence). In addition, imaging is performed by controlling the coil unit from the main unit according to the pulse sequence.

[0006] On the other hand, when using a wireless coil unit, the timing at which a control signal from the main unit to the coil unit changes must be wirelessly transmitted in accordance with a pulse sequence.

[0007] Here, if the timing of the change in the control signal of the coil unit is transmitted with a large delay compared to a wired connection, the imaging operation synchronized with the main unit may be disrupted, and imaging may not be performed correctly. Causes of imaging not being performed correctly include, for example, a shift in the timing of enabling the coil unit when the coil unit receives an MR signal, or settings to the coil unit not being performed at the default timing.

[0008] For example, a method of recovering a synchronous clock using wireless communication has been proposed as a conventional technique. However, in this method, due to the influence of fading occurring in the wireless propagation path, when the control signal transmitted from the main unit is recovered by the coil unit, a shift may occur in the timing at which the control signal changes. Also, during the pulse sequence, there are multiple points in time at which the control signal of the coil unit changes. Therefore, due to the influence of body movements caused by human breathing, etc., the situation of the wireless propagation path changes each time, and different timing shifts may occur each time, which is a problem in that it is difficult to correct each timing. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 5749317 Summary of the Invention [Problem to be solved by the invention]

[0010] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to improve the accuracy of imaging synchronization control with a main device in a wireless coil device. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described later can also be positioned as other problems. [Means for solving the problem]

[0011] The MRI apparatus according to the embodiment includes a main apparatus and a coil apparatus separate from the main apparatus. The main apparatus includes a first timer that operates with a synchronous clock. The coil apparatus includes a clock recovery unit, a second timer, and a detection unit. The clock recovery unit recovers the synchronous clock from a first wireless signal transmitted by the main apparatus. The second timer operates with the synchronous clock. The detection unit detects the timing of receiving a second wireless signal transmitted by the main apparatus. The MRI apparatus performs a synchronized imaging operation by correcting at least one of the first timer included in the main apparatus and the second timer included in the coil apparatus according to the timing. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of an MRI apparatus. [Diagram 2] FIG. 2 is a block diagram showing the functional configuration of the coil unit and the wireless section. [Diagram 3] FIG. 3 is a block diagram showing the clock transmission unit and the functional configuration of the clock transmission unit. [Figure 4] FIG. 4 is a block diagram showing a functional configuration of the detection unit. [Diagram 5] FIG. 5 is a diagram showing the time waveform of an RF pulse signal. [Figure 6] FIG. 6 is a diagram showing a time waveform of the reproduced synchronization correction timing. [Figure 7] FIG. 7 is a flowchart of the synchronization process executed by the control unit. [Figure 8] FIG. 8 is a sequence chart showing the timer synchronization process between the main unit and the coil unit. [Figure 9] FIG. 9 is a sequence chart showing timer synchronization processing between the main unit and the coil unit in another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] (Embodiment) The MRI apparatus according to this embodiment will be described below with reference to the drawings.

[0014] FIG. 1 is a diagram showing an example of the configuration of an MRI apparatus.

[0015] The MRI apparatus includes a main unit 101 and a coil unit 102. The main unit 101 includes a static magnetic field magnet 103, a gradient magnetic field coil 104, a gradient magnetic field power supply 105, a bed 106, a bed control unit 107, a transmission coil 108, an RF pulse generation unit 109, an RF pulse / gradient magnetic field control unit 110, a clock generation unit 111, a wireless unit 112, a data analysis unit 113, a storage unit 114, a display unit 115, an input unit 116, and an imaging control unit 117. The main unit 101 may be divided into a gantry and a processing unit. In this case, for example, the static magnetic field magnet 103, gradient magnetic field coil 104, gradient magnetic field power supply 105, bed 106, bed control unit 107, transmission coil 108, RF pulse generation unit 109, RF pulse / gradient magnetic field control unit 110 and wireless unit 112 are provided in the gantry, and the clock generation unit 111, data analysis unit 113, memory unit 114, display unit 115, input unit 116 and imaging control unit 117 are provided in the processing unit. Here, the main unit 101 is an example of a main device. Also, the coil unit 102 is an example of a coil device.

[0016] The static magnetic field magnet 103 has a hollow cylindrical shape and generates a uniform static magnetic field in the internal space. For example, a permanent magnet, a superconducting magnet, or the like is used as the static magnetic field magnet 103.

[0017] The gradient coil 104 has a hollow cylindrical shape and is disposed inside the static magnetic field magnet 103. The gradient coil 104 is a combination of three types of coils corresponding to the mutually orthogonal X, Y, and Z axes. The gradient coil 104 generates a gradient magnetic field whose magnetic field strength is inclined along each of the X, Y, and Z axes by the above three types of coils being individually supplied with current from a gradient magnetic field power supply 105. The Z-axis direction is, for example, the same direction as the static magnetic field direction. The gradient magnetic fields of the X, Y, and Z axes correspond, for example, to a slice selection gradient magnetic field Gs, a phase encoding gradient magnetic field Ge, and a readout gradient magnetic field Gr, respectively. The slice selection gradient magnetic field Gs is used to arbitrarily determine an imaging section. The phase encoding gradient magnetic field Ge is used to change the phase of an MR signal according to a spatial position. The readout gradient magnetic field Gr is used to change the frequency of an MR signal according to a spatial position.

[0018] The bed 106 moves the top board 106a in its longitudinal direction (left-right direction in FIG. 1) and vertical direction under the control of the bed control unit 107. Usually, the bed 106 is installed so that the longitudinal direction is parallel to the central axis of the static magnetic field magnet 103. A subject 118 is placed on the top board 106a. The bed 106 inserts the subject 118 into the space (imaging space) inside the gradient magnetic field coil 104 by moving the top board 106a.

[0019] The transmission coil 108 is configured by housing one or more coils in a cylindrical case. The transmission coil 108 is disposed inside the gradient magnetic field coil 104. The transmission coil 108 receives an RF pulse signal from an RF pulse generating unit 109 and emits an RF pulse.

[0020] The imaging control unit 117 has a CPU (Central Processing Unit), memory, etc., which are not shown, and plays a role in overall imaging control of the main unit, and executes pulse sequence information according to a main timer 119. Moreover, the imaging control unit 117 transfers the pulse sequence information from the wireless unit 112 to the coil unit 102 in advance. Here, the pulse sequence information is information that specifies the application timing and setting values ​​of each gradient magnetic field and RF pulse.

[0021] The imaging control unit 117 also generates a synchronization correction timing for synchronizing the main timer 119 included in the main unit 101 with the coil timer 226 included in the coil unit 102 based on the clock from the clock generation unit 111. Here, the synchronization correction timing is a 1-bit digital signal, and is assumed to be a signal that indicates the timing for correcting synchronization at the rise from 0 to 1, for example. The synchronization correction timing is used by the imaging control unit 117 as a timing for resetting the main timer 119 or acquiring the timer value of the main timer 119. The imaging control unit 117 also outputs the synchronization correction timing to the RF pulse / gradient magnetic field control unit 110 in order to generate an RF pulse based on the synchronization correction timing. Here, the imaging control unit 117 is an example of a second wireless signal transmission unit.

[0022] The RF pulse generating section 109 generates an RF pulse signal.

[0023] The RF pulse / gradient magnetic field control unit 110 controls the gradient magnetic field power supply 105 and the RF pulse generating unit 109 according to pulse sequence information input from the imaging control unit 117. Moreover, the RF pulse / gradient magnetic field control unit 110 controls the RF pulse generating unit 109 to emit an RF pulse according to the synchronization correction timing input from the imaging control unit 117. The RF pulse emitted here based on the synchronization correction timing is directly detected by the coil unit 102. Therefore, the RF pulse / gradient magnetic field control unit 110 may perform control to emit an RF pulse based on the synchronization correction timing with an intensity weaker than the intensity of the RF pulse emitted during imaging.

[0024] The coil unit 102 is placed on the tabletop 106a, built into the tabletop 106a, or attached to the subject 118. During imaging, the coil unit 102 is inserted into the imaging space together with the subject 118, and receives magnetic resonance echoes emitted from the subject 118 to obtain electrical echo signals. The coil unit 102 wirelessly transmits echo data obtained by digitizing the echo signals to the wireless unit 112. The coil unit 102 also receives a wireless clock signal from the wireless unit 112 to synchronize their system clocks.

[0025] The clock generating unit 111 generates a first clock signal of a predetermined frequency. This first clock signal is provided to the wireless unit 112 and the main timer 119, and is also used as a system clock that is a reference for the operation timing of the entire MRI apparatus. Here, the clock generating unit 111 is an example of a clock generating unit.

[0026] The main timer 119 is composed of a counter that operates based on a system clock, and the timer value of the main timer 119 is used to execute the pulse sequence according to a time schedule. Here, the main timer 119 may operate as a clock that handles time based on the system clock. Here, the main timer 119 is an example of a first timer.

[0027] The data analysis unit 113 analyzes the echo data and reconstructs an image of the object 118 .

[0028] The storage unit 114 stores various data such as image data representing the image reconstructed by the data analysis unit 113 .

[0029] The display unit 115 displays various information such as images reconstructed by the data analysis unit 113 and various operation screens for the user to operate the MRI apparatus under the control of the imaging control unit 117. As the display unit 115, a display device such as a liquid crystal display can be used.

[0030] The input unit 116 accepts various commands and information input from an operator. As the input unit 116, a pointing device such as a mouse or a trackball, a selection device such as a mode changeover switch, or an input device such as a keyboard can be appropriately used.

[0031] Fig. 2 is a block diagram showing the functional configuration of the coil unit 102 and the wireless unit 112. In Fig. 2, the same parts as in Fig. 1 are given the same reference numerals, and duplicated explanations will be omitted.

[0032] The coil unit 102 includes an RF receiving coil 201 , an RF receiving section 202 , an ADC 203 , a data communication section 204 , a data communication antenna 205 , a clock transmission section 206 , a clock transmission antenna 207 , a control section 208 , a detection section 227 , and a coil timer 226 .

[0033] The RF receiving coil 201 receives a magnetic resonance echo radiated from the subject 118 to obtain an electrical echo signal. The RF receiving coil 201 also receives an RF pulse based on the synchronization correction timing to obtain an electrical RF pulse signal. Here, the RF receiving coil 201 is an example of an RF receiving coil.

[0034] The detector 227 detects the envelope of the RF pulse signal, receives the synchronization correction timing, and reproduces it. Here, the timing at which the detector 227 is enabled to receive the synchronization correction timing is assumed to have been notified in advance from the main unit 101 via the data communication unit 204. Here, the detector 227 is an example of a detector.

[0035] The RF receiving unit 202 includes a variable amplifier that amplifies the echo signal obtained by the RF receiving coil 201, and amplifies the echo signal to an appropriate level before the ADC 203, thereby suppressing the influence of quantization errors.

[0036] The ADC 203 performs analog-to-digital conversion on the echo signal output as an analog signal by the RF receiving unit 202 based on a sampling clock supplied from the control unit 208, and obtains echo data as a digital signal.

[0037] The data communication unit 204 is composed of a modulation / demodulation circuit, a frequency conversion circuit, a power amplification circuit, etc. The data communication unit 204 generates a communication frame by adding a header, etc. to the echo data input from the ADC 203. Furthermore, the data communication unit 204 performs modulation processing, frequency conversion processing, etc. on the communication frame to generate a wireless communication signal, and transmits it from a data communication antenna 205.

[0038] Furthermore, the data communication unit 204 receives a wireless communication signal transmitted by the data communication unit 222 via the data communication antenna 205. Then, received data is obtained by performing frequency conversion processing, demodulation processing, etc. on the received wireless communication signal. As the received data, pulse sequence information, a timer correction value, the timing for enabling the detection unit 227, etc. are received and stored in a memory provided in the control unit 208.

[0039] The data communication unit 204 may be configured to control wireless communication conforming to the IEEE802.11 standard. The data communication unit 204 may be configured to control wireless communication conforming to communication standards such as Bluetooth (registered trademark), NFC, UWB, Zigbee, and MBOA. UWB is an abbreviation for Ultra Wide Band, and MBOA is an abbreviation for Multi Band OFDM Alliance. Here, OFDM is an abbreviation for Orthogonal Frequency Division Multiplexing. NFC is an abbreviation for Near Field Communication. UWB includes Wireless USB, Wireless 1394, Winet, and the like.

[0040] The clock transmission unit 206 receives a wireless clock signal transmitted by the clock transmission unit 224 via the clock transmission antenna 207. Here, the wireless clock signal is a wireless signal for frequency-synchronizing the system clocks of the main unit 101 and the coil unit 102. In addition, the clock transmission unit 206 regenerates a system clock from the wireless clock signal received by the clock transmission antenna 207, and outputs the system clock to the control unit 208 and the coil timer 226. Here, the clock transmission unit 206 is an example of a clock regeneration unit.

[0041] The coil timer 226 is configured with a counter that uses the system clock generated by the clock transmission unit 206 as its operating clock, and the timer value is used to execute the received pulse sequence information according to a time schedule. Note that the coil timer 226 may operate as a clock that uses the system clock as its operating clock. Here, the coil timer 226 is an example of a second timer.

[0042] The control unit 208 has a CPU, memory, etc. (not shown), and plays a role of overall imaging control of the coil unit 102, and executes pulse sequence information received via the data communication unit 204 in accordance with the coil timer 226. The control unit 208 also resets the coil timer 226 or acquires the timer value of the coil timer 226 according to the synchronization correction timing received by the detection unit 227. Furthermore, the control unit 208 generates a sampling clock from a system clock by a PLL (Phase Locked Loop) circuit (not shown), and outputs the sampling clock to the ADC 203.

[0043] The wireless unit 112 includes a control unit 221 , a data communication unit 222 , a data communication antenna 223 , a clock transmission unit 224 , and a clock transmission antenna 225 .

[0044] The control unit 221 wirelessly transmits the pulse sequence information input from the imaging control unit 117 from the data communication unit 222 to the coil unit 102. Furthermore, the control unit 221 controls the operation of the clock transmission unit 224 based on the pulse sequence information.

[0045] The configurations of the data communication unit 222 and the data communication antenna 223 are similar to those of the data communication unit 204 and the data communication antenna 205. The data communication unit 222 receives a wireless communication signal transmitted by the data communication unit 204 via the data communication antenna 223. Then, the data communication unit 222 acquires echo data from the received wireless communication signal and outputs the echo data to the data analysis unit 113. The data communication unit 222 also generates a wireless communication signal from pulse sequence information input from the control unit 221 and transmits the wireless communication signal to the coil unit 102.

[0046] The clock transmission unit 224 generates a wireless clock signal based on inputs from the clock generation unit 111 and the control unit 221, and transmits the signal from the clock transmission antenna 225. For example, the clock transmission unit 224 transmits the wireless clock signal as a wireless signal in a frequency band used in a wireless LAN (Local Area Network), such as a wireless signal in a frequency band used in the IEEE802.11 standard, Bluetooth (registered trademark), NFC, UWB, Zigbee, MBOA, etc. Here, the clock transmission unit 224 is an example of a first wireless signal transmission unit.

[0047] Next, the configurations and operations of clock transmission unit 206 and clock transmission unit 224 will be described.

[0048] FIG. 3 is a block diagram showing the functional configuration of clock transmission unit 206 and clock transmission unit 224. As shown in FIG.

[0049] The clock transmission unit 224 includes a code signal generation unit 301 and a clock transmission unit 302 .

[0050] The code signal generating unit 301 generates a coded code signal based on the first clock signal input from the clock generating unit 111 , and outputs the coded code signal to the clock transmitting unit 302 .

[0051] The clock transmitting unit 302 generates a wireless clock signal based on the code signal input from the code signal generating unit 301 , and transmits it from the clock transmission antenna 225 .

[0052] The clock transmission unit 206 includes a clock receiving unit 303 .

[0053] The clock receiving unit 303 receives the wireless clock signal transmitted from the clock transmitting unit 224 by the clock transmitting antenna 207. Then, the clock receiving unit 303 divides the frequency of this wireless clock signal, generates a second clock signal by a PLL having a jitter cleaner function, and outputs the second clock signal to the control unit 208. At this time, the second clock signal is equal to the first clock signal, and the system clock of the entire MRI apparatus is synchronized. However, when the control unit 208 performs frequency division, the second clock signal and the first clock signal may have an integer multiple or a fraction of an integer relationship. Here, the wireless clock signal transmitted and received by the clock transmitting unit 302 and the clock receiving unit 303 is a signal modulated by a binary Continuous Phase Frequency Shift Keying (CPFSK) method, or a frequency modulated signal that is not phase continuous.

[0054] Next, the configuration and operation of the detection unit 227 will be described.

[0055] FIG. 4 is a block diagram showing the functional configuration of the detection unit 227.

[0056] The detection unit 227 is an envelope detection circuit that can be configured by a diode 401, a capacitor 402, and a resistor 403. The detection unit 227 may include an AGC (Automatic Gain Control) circuit and a band limiting filter (not shown), adjust the amplitude of the RF pulse signal 404 from the RF receiving coil 201, and input the adjusted amplitude to the diode 401. The diode 401 rectifies the RF pulse signal. The time constant of the capacitor 402 and the resistor 403 is determined according to the period of the RF pulse signal, and outputs a synchronization correction timing 405 that is an envelope of the RF pulse signal 404. The circuit configuration shown here is merely an example, and may be realized by another circuit as long as the circuit configuration is capable of reproducing the synchronization correction timing transmitted by the RF pulse signal.

[0057] FIG. 5 is a diagram showing the time waveform of the RF pulse signal 404.

[0058] The RF pulse signal 404 for transmitting the synchronization correction timing from the RF receiving coil 201 has a frequency that can be detected by the RF receiving coil 201. For example, this can be realized by outputting a continuous sine wave 500 only during the period when the synchronization correction timing is 1. Here, as the frequency for emitting the RF pulse, a radio signal having a frequency of, for example, 63.9 MHz or 128 MHz, which is included in the frequency band of the Larmor frequency, can be used.

[0059] FIG. 6 is a diagram showing a time waveform of the reproduced synchronization correction timing 405.

[0060] The synchronization correction timing reproduced by the detection unit 227 is a rectangular output that is an envelope 600 of a sine wave 500, and the synchronization correction timing generated by the imaging control unit 117 and transmitted as an RF pulse is reproduced in the coil unit .

[0061] Next, an operation for the coil timer 226 to perform timer synchronization with the main timer 119 in the MRI apparatus of this embodiment having the above configuration will be described.

[0062] FIG. 7 is a flowchart of the synchronization process executed by the control unit 208.

[0063] In S701, the control unit 208 receives a wireless clock signal. In S702, the control unit 208 regenerates the system clock from the received wireless clock signal.

[0064] In S703, the control unit 208 enables the detection unit 227 and the RF receiving coil 201 in response to a timer synchronization processing start notification transmitted from the control unit 221 of the main unit 101 via the data communication unit 204 or the clock transmission unit 206.

[0065] In S704, the control unit 208 determines whether or not an RF pulse has been detected, and waits in S705 until an RF pulse is detected. If an RF pulse has been detected, the control unit 208 proceeds to S706.

[0066] In S706, the control unit 208 recovers the synchronization timing from the detected RF pulse, and resets the coil timer 226 at the recovered synchronization correction timing, thereby establishing synchronization with the main timer 119.

[0067] In S707, the control unit 208 disables the detection unit 227 and the RF receiving coil 201. This is control so that the detection unit 227 and the RF receiving coil 201 do not respond to an RF pulse during imaging.

[0068] In S708, the control unit 208 detects whether the system clock is out of synchronization, and if out of synchronization, repeats the operations from S703 after the system clock is resynchronized, and re-establishes timer synchronization. Here, the control unit 208 is an example of an out-of-synchronization detection unit.

[0069] If the system clock is not out of synchronization in S708, the control unit 208 ends the timer synchronization process.

[0070] Here, whether or not the system clock has become out of synchronization is determined by a lock detection circuit of the PLL provided in the clock receiving unit 303. Lock detection may be performed by determining the phase difference at the time of phase comparison in the PLL using a threshold value, or may be performed using another method.

[0071] Next, an operation in which the main unit 101 and the coil unit 102 perform timer synchronization before starting imaging will be described.

[0072] FIG. 8 is a sequence chart showing timer synchronization processing between the main unit 101 and the coil unit 102. In FIG.

[0073] In S801, the main unit 101 transmits a wireless clock signal, and in S802, the coil unit 102 receives the transmitted wireless clock signal.

[0074] In S803, the coil unit 102 recovers the system clock from the radio clock signal.

[0075] Here, it is assumed that the wireless clock signal is continuously transmitted from when the MRI apparatus is powered on and during operation, and the system clock is always reproduced in the coil unit 102.

[0076] In S804, the coil timer 226 starts a count operation based on the system clock. The main timer 119 of the main unit 101 starts a count operation from the point when the system clock is supplied upon power-on.

[0077] In S805, the main unit 101 transmits a timer synchronization processing start notification via the data communication unit 222, and in S806, the coil unit 102 receives the timer synchronization processing start notification via the data communication unit 204.

[0078] In S807, the coil unit 102 enables the detection unit 227 and the RF receiving coil 201.

[0079] In S808, the main unit 101 emits an RF pulse for transmitting the synchronization correction timing.

[0080] In S809, the main unit 101 resets the main timer 119 at the timing when it emits an RF pulse for transmitting the synchronization correction timing.

[0081] In S810, the coil unit 102 detects the RF pulse and recovers the synchronization correction timing.

[0082] In S811, the coil unit 102 resets the coil timer 226 at the reproduced synchronization correction timing, thereby establishing timer synchronization with the main timer 119.

[0083] In S812, the coil unit 102 disables the detection unit 227 and the RF receiving coil 201.

[0084] In S813, the main unit 101 transmits the pulse sequence via the data communication unit 222.

[0085] In S814, the coil unit 102 receives the pulse sequence via the data communication unit 204 and stores it in memory.

[0086] In S815, the main unit 101 transmits a start timer value as the shooting start timing, and the main timer 119 waits until the start timer value matches this value.

[0087] In S816, the coil unit 102 receives the imaging start timing and waits until the coil timer 226 matches the start timer value.

[0088] In S817, when the main timer 119 and the coil timer 226 match the start timer value, MRI imaging is synchronously performed.

[0089] In this embodiment, the delay from when the synchronization correction timing is generated by the imaging control unit 117 until when it is reproduced by the detection unit 227 of the coil unit 102 becomes a synchronization error between the main timer 119 and the coil timer 226. For this reason, the transmission delay of the RF pulse may be set in advance as the timer initial value at the time of reset.

[0090] The technology disclosed in the present application can also be realized by executing the following process. That is, software (programs) that realize the functions of the above-described embodiments are supplied to a system or device via a network or various storage media, and a computer (or a CPU or MPU (Micro Processing Unit) or the like) of the system or device reads and executes the program. The process may also be executed by a circuit (e.g., ASIC (Application Specific Integrated Circuit)) that realizes one or more functions.

[0091] (Other embodiments) In the above-described embodiment, the main unit 101 resets the main timer 119 at the timing when it transmits the synchronization correction timing, and the coil unit 102 resets the coil timer 226 at the received synchronization correction timing, thereby establishing timer synchronization.

[0092] In another embodiment, for example, timer synchronization may be achieved by calculating a correction value from the timer value of each timer based on the synchronization correction timing, and correcting the main timer 119 or the coil timer 226.

[0093] FIG. 9 is a sequence chart showing timer synchronization processing between the main unit 101 and the coil unit 102 in another embodiment.

[0094] The processing in S901 to S908 is the same as the processing in S801 to S808, and therefore the description thereof will be omitted.

[0095] In S909, the main unit 101 acquires the timer value T1 of the main timer 119 at the synchronous correction timing, and stores it in memory.

[0096] In S910, the coil unit 102 detects the RF pulse and recovers the synchronization correction timing.

[0097] In S911, the coil unit 102 obtains the timer value T2 of the coil timer 226 at the reproduced synchronization correction timing, and stores it in the memory.

[0098] In S912, the coil unit 102 disables the detection unit 227 and the RF receiving coil 201.

[0099] In S913, the main unit 101 transmits the timer value T1 through the data communication section 222.

[0100] In S914, the coil unit 102 receives the timer value T1 via the data communication unit 204. Then, the control unit 208 of the coil unit 102 calculates the timer correction value Td of the coil timer 226 by the following formula (1).

[0101] Td = T2−T1...Equation (1)

[0102] In S915, the control unit 208 of the coil unit 102 establishes timer synchronization with the main timer 119 by correcting the coil timer 226 with the timer correction value Td.

[0103] The processing in S916 to S920 is the same as the processing in S813 to S817, and therefore the description thereof will be omitted.

[0104] Note that, here, in steps S913 to S915, the main unit 101 transmits the timer value T1 to the coil unit 102, and the coil unit 102 corrects the coil timer 226 to establish timer synchronization, but the embodiment is not limited to this. For example, in steps S913 to S915, the coil unit 102 may transmit the timer value T2 to the main unit 101, and the main unit 101 may calculate the difference between the timer values ​​and correct the main timer 119 to establish timer synchronization.

[0105] Also, in S915, the coil unit 102 may set Td as an initial value of the coil timer 226 instead of correcting the coil timer 226, and in S918, when notifying the imaging start timing, reset the main timer 119 and the coil timer 226 to establish timer synchronization. In this case, in S918, the main unit 101 transmits the imaging start timing by an RF pulse in the same manner as the synchronization correction timing, thereby enabling synchronous imaging that takes into account the propagation delay and the internal delay of the transmission and reception circuit.

[0106] In addition, in the above-described embodiment, the RF pulse generating unit 109 and the RF receiving coil 201 are used as a means for transmitting the synchronization correction timing. However, this is not limited to this, and the synchronization correction timing may be realized by using, for example, a wireless signal in a frequency band used in the IEEE802.11 standard, Bluetooth (registered trademark), NFC, UWB, Zigbee, MBOA, etc.

[0107] According to the above-described embodiment, it is possible to reduce the cost of the circuit added to the coil unit 102 while reducing the deviation in the timing of the change in the control signal due to fading, thereby improving the accuracy of the imaging synchronization control between the wireless coil unit 102 and the main unit 101.

[0108] In the above-described embodiment, for example, each processing unit included in the main unit 101 and the coil unit 102 may be realized by one or more processing circuits. In this case, each processing circuit is realized by, for example, a processor. In this case, the processing function of each processing circuit is stored in, for example, a storage circuit in the form of a program executable by a computer. Then, each processing circuit realizes the processing function corresponding to each program by reading out each program from the storage circuit and executing it.

[0109] Here, for example, each processing circuit may be configured by combining multiple independent processors, and each processor may execute a program to realize each processing function. Also, the processing functions of each processing circuit may be appropriately distributed or integrated into a single or multiple processing circuits to realize them. Also, the storage circuit in which the program corresponding to each processing function is stored may be a single storage circuit, or multiple storage circuits may be distributed and arranged for each processing circuit, and each processing circuit may read out the corresponding program from the individual storage circuit.

[0110] Further, each processing unit included in the main unit 101 and the coil unit 102 may be realized by a processing circuit, or may be realized by hardware only, software only, or a combination of hardware and software.

[0111] In the above description, the "processor" reads out and executes a program corresponding to each processing function from a storage circuit, but the embodiment is not limited to this. The term "processor" refers to a circuit such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an Application Specific Integrated Circuit (ASIC), a programmable logic device (e.g., a Simple Programmable Logic Device (SPLD), a Complex Programmable Logic Device (CPLD), and a Field Programmable Gate Array (FPGA)). When the processor is a CPU, for example, the processor realizes each processing function by reading out and executing a program stored in a storage circuit. On the other hand, when the processor is an ASIC, instead of storing a program in a storage circuit, the processing function is directly incorporated as a logic circuit in the circuit of the processor. Note that each processor in the present embodiment is not limited to being configured as a single circuit for each processor, and may be configured as a single processor by combining multiple independent circuits to realize the processing function. Furthermore, multiple components in FIG. 1 may be integrated into one processor to realize the processing functions.

[0112] Here, the program executed by the processor is provided by being pre-installed in a ROM (Read Only Memory), a storage circuit, or the like. The program may be provided by being recorded in a computer-readable non-transitory storage medium such as a CD (Compact Disk)-ROM, a FD (Flexible Disk), a CD-R (Recordable), or a DVD (Digital Versatile Disk) in a format that can be installed in these devices or in a format that can be executed. The program may also be provided or distributed by being stored on a computer connected to a network such as the Internet and downloaded via the network. For example, the program is composed of modules including each of the above-mentioned functional units. As actual hardware, a CPU reads out the program from a storage medium such as a ROM and executes it, so that each module is loaded onto a main storage device and generated on the main storage device.

[0113] In the above-described embodiment, each component of each device shown in the figure is a functional concept, and does not necessarily have to be physically configured as shown in the figure. In other words, the specific form of distribution or integration of each device is not limited to that shown in the figure, and all or a part of it can be functionally or physically distributed or integrated in any unit according to various loads, usage conditions, etc. Furthermore, all or any part of each processing function performed by each device can be realized by a CPU and a program analyzed and executed by the CPU, or can be realized as hardware using wired logic.

[0114] Furthermore, among the processes described in the above embodiments, all or part of the processes described as being performed automatically can be performed manually, or all or part of the processes described as being performed manually can be performed automatically by a known method. In addition, the information including the processing procedures, control procedures, specific names, various data and parameters shown in the above documents and drawings can be changed arbitrarily unless otherwise specified.

[0115] According to at least one of the embodiments described above, it is possible to improve the accuracy of imaging synchronization control with the main device in a wireless coil device.

[0116] Although some embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations of embodiments can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0117] 101 Main unit 102 Coil unit 111 Clock Generation Unit 117 Imaging control section 119 Main Timer 201 RF receiving coil 206 Clock transmission section 208 Control Unit 224 Clock transmission section 226 Coil Timer 227 Detection Unit

Claims

1. The main device, A coil device separate from the main device; Equipped with the main device includes a first timer that operates on a synchronous clock; The coil device includes: a clock recovery unit that recovers the synchronous clock from a first wireless signal transmitted by the main device; a second timer that operates on the synchronous clock; a detection unit that detects a timing at which the second wireless signal transmitted by the main device is received; having at least one of the first timer included in the main device and the second timer included in the coil device is corrected according to the timing, thereby performing a synchronized imaging operation. Magnetic resonance imaging device.

2. the main device resets the first timer at a timing when the second wireless signal is transmitted; 2. A magnetic resonance imaging apparatus according to claim 1.

3. the coil device resets the second timer at a timing when the second wireless signal is received; 3. A magnetic resonance imaging apparatus according to claim 1 or 2.

4. the main device holds a first timer value of the first timer at a timing when the second wireless signal is transmitted; 2. A magnetic resonance imaging apparatus according to claim 1.

5. the coil device holds a second timer value of the second timer at a timing when the second wireless signal is received; 5. A magnetic resonance imaging apparatus according to claim 1.

6. correcting one of the first timer and the second timer based on a difference between a timer value of the first timer and a timer value of the second timer; 6. A magnetic resonance imaging apparatus according to claim 5.

7. The coil device further includes an out-of-sync detection unit that detects whether the recovered synchronous clock is out of sync, when the synchronization of the synchronous clock is lost, after the synchronous clock is resynchronized, at least one of the first timer and the second timer is corrected again in accordance with the timing detected by the detection unit; 3. A magnetic resonance imaging apparatus according to claim 1 or 2.

8. The second radio signal is a radio signal having a frequency included in the Larmor frequency band used during imaging.

3. A magnetic resonance imaging apparatus according to claim 1 or 2.

9. The first wireless signal is a wireless signal in a frequency band used in a wireless LAN (Local Area Network), 3. A magnetic resonance imaging apparatus according to claim 1 or 2.

10. the second radio signal is transmitted at a signal strength weaker than the Larmor frequency radio signal used during the imaging; 9. A magnetic resonance imaging apparatus according to claim 8.

11. the main device transmits the second wireless signal as an RF (Radio Frequency) pulse signal; the coil device further includes an RF receiving coil for receiving the second wireless signal; The detection unit detects the timing by detecting an envelope of the second radio signal received by the RF receiving coil.

3. A magnetic resonance imaging apparatus according to claim 1 or 2.

12. The main device includes: A clock generating unit that generates the synchronous clock; a first wireless signal transmitting unit that generates the first wireless signal based on the synchronous clock and transmits the first wireless signal to the coil device by wireless communication; a second wireless signal transmitting unit that generates the second wireless signal based on the synchronous clock and transmits the second wireless signal to the coil device by wireless communication; 3. The magnetic resonance imaging apparatus according to claim 1, further comprising:

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