JP6571388B2 - Magnetic resonance imaging system - Google Patents

Description

  Embodiments described herein relate generally to a magnetic resonance imaging apparatus.

  The nuclear spin of a subject placed in a static magnetic field is magnetically excited with a RF frequency (Larmor frequency) RF (Radio Frequency) pulse. There is a magnetic resonance imaging (MRI) apparatus that is configured.

  Such a magnetic resonance imaging apparatus, for example, raises the temperature of the metal shim provided in the gradient magnetic field coil before the protocol is executed, thereby suppressing fluctuations in the temperature of the metal shim. Thereby, the fluctuation | variation of the center frequency of RF pulse is suppressed and degradation of the image quality of an image is suppressed.

JP 2010-269136 A JP 2010-104696 A JP 2008-114051 A JP 2012-30051 A

  The problem to be solved by the present invention is to provide a magnetic resonance imaging apparatus capable of suppressing the influence on imaging due to the temporal change of the temperature of the metal shim.

The magnetic resonance imaging apparatus of the embodiment includes a gradient magnetic field coil, a derivation unit, a sequence control unit, and a reception unit . The gradient magnetic field coil applies a gradient magnetic field in a static magnetic field where a subject is placed. The deriving unit derives a time schedule for one examination including a series of protocol groups, using a temperature change model indicating a temporal change in the temperature of the gradient coil. The sequence control unit sequentially executes the protocols included in the protocol group according to the time schedule. The accepting unit accepts input of desired conditions regarding image quality from the operator. The deriving unit derives the time schedule according to the desired condition.

FIG. 1 is a functional block diagram showing the configuration of the MRI apparatus according to the embodiment. FIG. 2 is a perspective view showing an example of the structure of the gradient coil. FIG. 3 is a structural diagram showing an example of an internal structure of the gradient coil shown in FIG. FIG. 4 is a diagram illustrating an example of the flow of condition reception processing. FIG. 5 is a diagram illustrating an example of a condition setting screen. FIG. 6A is a diagram illustrating an example of the flow of imaging control processing. FIG. 6B is a diagram illustrating an example of the flow of imaging control processing. FIG. 7 is a diagram illustrating an example of an imaging condition setting screen in the embodiment. FIG. 8 is a diagram illustrating an example of TR and a waveform of current supplied to each of the three coils forming the gradient magnetic field coil by executing the selected protocol. FIG. 9 is a diagram illustrating an example of a temperature rise model. FIG. 10 is a diagram illustrating an example of a temperature decrease model. FIG. 11 is a diagram for explaining an example of a method for calculating a temperature increase coefficient. FIG. 12 is a diagram showing an example of a preheat temperature rise model showing temporal changes in the temperature of the iron shim when a preheating current is supplied to each of the three coils forming the gradient coil. FIG. 13 shows the temperature of the iron shim when the current supply to each of the three coils forming the gradient coil is stopped and the gradient coil is cooled by supplying water to the gradient coil by the cooling system. It is a figure which shows an example of the cooling temperature fall model which shows a time change. FIG. 14 is a diagram illustrating an example of a result of executing steps S204 to S213 in FIG. 6A. FIG. 15 is a diagram illustrating an example of a result when the protocols are executed in the same order set in step S202 and a result when the order of the protocols to be executed is rearranged by executing steps S215 to S220. is there. FIG. 16 is a diagram illustrating an example of a result when the protocols are executed in the same order set in step S202 and a result when the order of the protocols to be executed is rearranged by executing steps S221 to S226. is there. FIG. 17 is a diagram for explaining another process performed by the setting function. FIG. 18 is a diagram illustrating an example of the flow of the preheat determination process. FIG. 19 is a diagram for explaining another process performed by the setting function. FIG. 20 is a diagram illustrating an example of information that is displayed on the display by the display control function and that indicates the timing at which the protocol is executed.

  Hereinafter, a magnetic resonance imaging apparatus (hereinafter referred to as “MRI apparatus” as appropriate) according to an embodiment will be described with reference to the drawings. Note that the embodiments are not limited to the following embodiments.

  FIG. 1 is a functional block diagram showing a configuration of an MRI apparatus 100 according to the embodiment. As shown in FIG. 1, the MRI apparatus 100 includes a static magnetic field magnet 101, a static magnetic field power supply 102, a gradient magnetic field coil 103, a gradient magnetic field power supply 104, a bed 105, a bed control circuit 106, and a transmission coil 107. , A transmission circuit 108, a reception coil 109, a reception circuit 110, a sequence control circuit 120, a calculator 130, and a temperature sensor 140. The MRI apparatus 100 does not include the subject P (for example, a human body) shown in FIG. Moreover, the structure shown in FIG. 1 is only an example.

  A cooling system 200 is connected to the gradient magnetic field coil 103 of the MRI apparatus 100 via a cooling pipe 103f described later.

  The static magnetic field magnet 101 is a magnet formed in a hollow cylindrical shape (including a magnet whose cross section perpendicular to the axis of the cylinder is elliptical), and generates a static magnetic field in an internal space. For example, the static magnetic field magnet 101 is excited when a current is supplied from the static magnetic field power source 102 to generate a static magnetic field. The static magnetic field magnet 101 may be a permanent magnet.

  The static magnetic field power supply 102 supplies a current to the static magnetic field magnet 101. When the static magnetic field magnet 101 is a permanent magnet, the MRI apparatus 100 does not have to be provided with the static magnetic field power source 102.

The gradient magnetic field coil 103 is a coil formed in a hollow cylindrical shape (including a coil whose cross section perpendicular to the axis of the cylinder is elliptical), and is disposed inside the static magnetic field magnet 101. The gradient coil 103 is formed by combining three coils corresponding to the X, Y, and Z axes orthogonal to each other, and these three coils individually supply current from the gradient magnetic field power supply 104. In response, a gradient magnetic field is generated in which the magnetic field strength varies along the X, Y, and Z axes. The gradient magnetic fields of the X, Y, and Z axes generated by the gradient coil 103 are, for example, a slice gradient magnetic field G _SS , a phase encoding gradient magnetic field G _PE , and a read gradient magnetic field G _RO . That is, the gradient magnetic field coil 103 applies a gradient magnetic field in the static magnetic field where the subject P is placed.

  The gradient magnetic field power supply 104 supplies a current to the gradient magnetic field coil 103. For example, the gradient magnetic field power supply 104 individually supplies a current to each of three coils forming the gradient magnetic field coil 103.

  The couch 105 includes a couchtop 105a on which the subject P is placed. Under the control of the couch control circuit 106, the couchtop 105a is placed in the cavity (with the subject P placed) on the cavity ( Insert it into the imaging port. Usually, the bed 105 is installed so that the longitudinal direction is parallel to the central axis of the static magnetic field magnet 101.

  The couch control circuit 106 is a processor that drives the couch 105 and moves the couchtop 105a in the longitudinal and vertical directions under the control of the computer 130.

  The transmission coil 107 is disposed inside the gradient magnetic field coil 103 and receives a supply of RF pulses from the transmission circuit 108 to generate a high-frequency magnetic field.

  The transmission circuit 108 is a processor that supplies an RF pulse corresponding to a Larmor frequency determined by the type of target atom and the magnetic field strength to the transmission coil 107.

  The reception coil 109 is disposed inside the gradient magnetic field coil 103 and receives a magnetic resonance signal (hereinafter referred to as “MR signal” as appropriate) emitted from the subject P due to the influence of the high-frequency magnetic field. When receiving the MR signal, the receiving coil 109 outputs the received MR signal to the receiving circuit 110.

  Note that the transmission coil 107 and the reception coil 109 described above are merely examples. What is necessary is just to comprise by combining one or more among the coil provided only with the transmission function, the coil provided only with the reception function, or the coil provided with the transmission / reception function.

  The receiving circuit 110 is a processor that detects the MR signal output from the receiving coil 109 and generates MR data based on the detected MR signal. Specifically, the receiving circuit 110 generates MR data by digitally converting the MR signal output from the receiving coil 109. The receiving circuit 110 transmits the generated MR data to the sequence control circuit 120. The receiving circuit 110 may be provided on the gantry device side including the static magnetic field magnet 101, the gradient magnetic field coil 103, and the like.

  The sequence control circuit 120 is a processor that images the subject P by driving the gradient magnetic field power source 104, the transmission circuit 108, and the reception circuit 110 based on the sequence information transmitted from the computer 130. Here, the sequence information is information defining a procedure for performing imaging. The sequence information includes the strength of the current supplied from the gradient magnetic field power source 104 to the gradient magnetic field coil 103, the timing of supplying the current, the strength of the RF pulse supplied from the transmission circuit 108 to the transmission coil 107, the timing of applying the RF pulse, and reception. The timing at which the circuit 110 detects the MR signal is defined. The sequence control circuit 120 is an example of a sequence control unit described in the claims.

  The sequence control circuit 120 drives the gradient magnetic field power source 104, the transmission circuit 108, and the reception circuit 110 to image the subject P. As a result, when receiving MR data from the reception circuit 110, the sequence control circuit 120 sends the received MR data to the computer 130. Forward.

  The computer 130 performs overall control of the MRI apparatus 100, image generation, and the like. The computer 130 includes an interface circuit 131, a storage circuit 132, a processing circuit 133, an input circuit 134, a display 135, and an image generation circuit 136.

  The interface circuit 131 is realized by a processor. The interface circuit 131 transmits sequence information to the sequence control circuit 120 and receives MR data from the sequence control circuit 120. Further, when receiving the MR data, the interface circuit 131 stores the received MR data in the storage circuit 132. The MR data stored in the storage circuit 132 is arranged in the k space by the processing circuit 133. As a result, the storage circuit 132 stores k-space data.

  The storage circuit 132 stores MR data received by the interface circuit 131, k-space data arranged in the k space by the processing circuit 133, image data generated by the image generation circuit 136, and the like. The storage circuit 132 stores various programs. The storage circuit 132 also stores setting information, imaging conditions, correspondence table, protocol temperature difference information, examination reservation information, and the like, which will be described later. The storage circuit 132 is realized by, for example, a RAM (Random Access Memory), a semiconductor memory element such as a flash memory, a hard disk, an optical disk, or the like.

  The input circuit 134 receives various instructions and information input from an operator such as a doctor or a medical radiographer. The input circuit 134 is realized by, for example, a trackball, a switch button, a mouse, a keyboard, and the like. The input circuit 134 is connected to the processing circuit 133, converts the input operation received from the operator into an electrical signal, and outputs it to the processing circuit 133.

  The display 135 displays various GUIs (Graphical User Interface), images generated by the image generation circuit 136, and the like under the control of the processing circuit 133.

  The image generation circuit 136 is a processor that reads k-space data from the storage circuit 132 and generates an image by performing reconstruction processing such as Fourier transform on the read k-space data.

  The processing circuit 133 is a processor that performs overall control of the MRI apparatus 100 and controls imaging, image generation, image display, and the like. For example, the processing circuit 133 receives input of imaging conditions on the GUI, generates sequence information according to the received imaging conditions, and transmits the generated sequence information to the sequence control circuit 120. Further, the processing circuit 133 executes a reception function 133a, a setting function 133b, and a display control function 133c.

  Here, for example, the processing functions of the reception function 133a, the setting function 133b, and the display control function 133c that are components of the processing circuit 133 are stored in the storage circuit 132 in the form of a program that can be executed by a computer. The processing circuit 133 implements a function corresponding to each program by reading each program from the storage circuit 132 and executing each read program. In other words, the processing circuit 133 in a state where each program is read has the functions shown in the processing circuit 133 of FIG. In FIG. 1, it has been described that the processing functions of the reception function 133a, the setting function 133b, and the display control function 133c are realized by a single processing circuit 133, but a plurality of independent processors are combined. The processing circuit 133 may be configured and each processing function may be realized by each processor executing each program.

  The term “processor” used in the above description refers to, for example, a central preprocess unit (CPU), a graphics processing unit (GPU), or an application specific integrated circuit (ASIC), programmable logic device (for example, It means a circuit such as a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA). Instead of storing the program in the storage circuit 132, the program may be directly incorporated in the processor circuit. In this case, the processor realizes the function by reading and executing the program incorporated in the circuit.

  The temperature sensor 140 is provided in the vicinity of the gradient magnetic field coil 103, detects the temperature of the gradient magnetic field coil 103, and outputs a signal indicating the detected temperature to the interface circuit 131. In addition, the temperature of the iron shim 103e described later increases as the temperature of the gradient coil 103 increases, and decreases as the temperature of the gradient coil 103 decreases. The temperature of the gradient coil 103 and the temperature of the iron shim 103e are substantially the same. Therefore, the computer 130 can handle the temperature of the gradient coil 103 detected by the temperature sensor 140 as the temperature of the iron shim 103e.

  For example, the cooling system 200 causes water to flow into the gradient magnetic field coil 103 by flowing water adjusted to a predetermined temperature (for example, 20 degrees) toward the gradient magnetic field coil 103 through a cooling pipe 103f described later. In addition, when the water that has flowed through the gradient magnetic field coil 103 returns via the cooling pipe 103f, the cooling system 200 cools the returned water to a predetermined temperature and then directs the water toward the gradient magnetic field coil 103. Then, it flows again into the cooling pipe 103f. In this way, the cooling system 200 circulates water between the gradient magnetic field coil 103, and when no current is supplied to the gradient magnetic field coil 103 and the gradient magnetic field coil 103 is not generating heat, The temperature of the iron shim 103e is controlled so that the temperature of an iron shim 103e (described later) provided in the gradient magnetic field coil 103 is approximately the same as the temperature of water. In addition, the cooling system 200 always supplies water adjusted to a predetermined temperature to the gradient magnetic field coil 103.

  Here, even when water adjusted to a predetermined temperature is supplied into the gradient magnetic field coil 103, when the current is supplied to the gradient magnetic field coil 103 and the gradient magnetic field coil 103 is generating heat, the iron shim 103e. Is affected by the heat generated by the gradient coil 103 and becomes equal to or higher than the temperature of water.

  The overall configuration of the MRI apparatus 100 according to the embodiment has been described above. Here, in the MRI apparatus, when preheating for increasing the temperature of the iron shim provided in the gradient magnetic field coil is executed before the imaging protocol is executed, the preheating execution time is long for the operator. May feel like this. For this reason, there is a problem that the operator feels a long time from the start of the examination until imaging is performed by executing the protocol. That is, there is a problem that there is a temporal influence on imaging due to a temporal change in the temperature of the iron shim.

  A case will be described in which the MRI apparatus executes a plurality of protocols in the order determined in the imaging conditions regardless of the value of the temperature of the iron shim immediately before the execution of each of the plurality of protocols. For example, a case will be described in which each protocol is executed in ascending order of the saturation temperature as an imaging condition, and the temperature of the iron shim is already high when the MRI apparatus executes the first protocol. Note that the saturation temperature refers to, for example, an upper limit value of the temperature at which the iron shim fluctuates when the protocol is executed, and this upper limit value is uniquely determined according to the type of protocol. In such a case, when a plurality of protocols are executed in the order determined as imaging conditions in the MRI apparatus, if the protocol executed last is executed as it is, an iron shim or a gradient coil Temperature exceeds the allowable temperature of the MRI apparatus. For this reason, in the MRI apparatus, a waiting time may occur before the protocol executed last is executed. Therefore, there is a problem that it takes a long time from the start of inspection until imaging is performed by executing the protocol. That is, even in this case, there is a problem that there is a temporal influence on imaging due to a temporal change in the temperature of the iron shim.

  Further, a case will be described in which each protocol is determined to be executed in descending order of the saturation temperature as an imaging condition of the MRI apparatus. In such a case, when a plurality of protocols are executed in descending order of the saturation temperature defined as the imaging condition in the MRI apparatus, the temperature of the iron shim at the start of execution of the first executed protocol and the execution completion The difference with the temperature of the iron shim at the time is large. For this reason, for example, when a plurality of images are taken by executing a single protocol, there is a problem that the image quality of the reconstructed image deteriorates. That is, there is a problem that there is an image quality influence on imaging due to temporal changes in the temperature of the iron shim.

  Therefore, based on the above-described configuration, the MRI apparatus 100 according to the embodiment can suppress various effects on imaging due to temporal changes in the temperature of the iron shim, as will be described in detail below. It is configured.

  Next, an example of the structure of the gradient magnetic field coil 103 shown in FIG. 1 will be described. FIG. 2 is a perspective view showing an example of the structure of the gradient coil 103. As shown in the example of FIG. 2, the gradient magnetic field coil 103 includes a main coil 103 a that applies a gradient magnetic field in the X-axis, Y-axis, and Z-axis directions by the current supplied from the gradient magnetic field power supply 104, and the main coil 103 a. A shield coil 103b for canceling the leakage magnetic field.

  Here, a plurality of shim tray insertion guides 103c are formed between the main coil 103a and the shield coil 103b. A shim tray 103d containing an iron shim 103e that corrects spatial nonuniformity of the static magnetic field in the bore is inserted into the shim tray insertion guide 103c. The iron shim 103e is an example of a metal shim described in the claims.

  Each shim tray insertion guide 103 c is a through hole that forms an opening on both end faces of the gradient magnetic field coil 103, and is formed over the entire length in the longitudinal direction of the gradient magnetic field coil 103. Each shim tray insertion guide 103c is formed at equal intervals in the circumferential direction so as to be parallel to each other in a region sandwiched between the main coil 103a and the shield coil 103b. A shim tray 103d is inserted into each shim tray insertion guide 103c.

  The shim tray 103d is made of a resin that is a nonmagnetic and nonconductive material, and has a substantially rod shape. A predetermined number of iron shims 103e are stored in the shim tray 103d. The shim tray 103 d is inserted into the shim tray insertion guide 103 c and fixed to the center of the gradient magnetic field coil 103.

  Although not shown in FIG. 2, the gradient magnetic field coil 103 has a cooling pipe embedded in a spiral shape along a cylindrical shape. FIG. 3 is a structural diagram showing an example of the internal structure of the gradient coil 103 shown in FIG. 3 shows a part of the gradient magnetic field coil 103, in which the upper side shows the outer side of the cylindrical shape, and the lower side shows the inner side of the cylindrical shape.

  As shown in the example of FIG. 3, the gradient magnetic field coil 103 includes inner and outer sides of the shim tray insertion guide 103c, that is, between the shim tray insertion guide 103c and the main coil 103a, and between the shim tray insertion guide 103c and the shield coil 103b. In between, the cooling pipe 103f is embedded helically. The water sent from the cooling system 200 flows into the cooling pipe 103 f, and the inflowed water circulates inside the gradient magnetic field coil 103 through the cooling pipe 103 f and then flows out of the gradient magnetic field coil 103. Thus, the water circulates through the cooling pipe 103f and the inside of the gradient magnetic field coil 103, whereby the gradient magnetic field coil 103 and the iron shim 103e provided in the gradient magnetic field coil 103 are cooled.

  Next, each processing function of the reception function 133a, the setting function 133b, and the display control function 133c executed by the processing circuit 133 shown in FIG. 1 will be described.

  The reception function 133a displays a condition setting screen for receiving various conditions for setting the protocol execution mode on the display 135, and receives various conditions from the operator. For example, the reception function 133a waits without doing anything before executing the protocol to be executed, and controls to reduce the temperature of the iron shim 103e and the gradient coil 103 by the cooling system 200 that is always operating (hereinafter, In some cases, it is referred to as “waiting control”) and the preheat execution time is received. The reception function 133a is an example of a reception unit described in the claims. In addition, preheating here refers to raising the temperature of the iron shim 103e, for example, before performing the protocol of execution object. In the preheating in the present embodiment, when the preheating current is supplied to the gradient magnetic field coil 103, the gradient magnetic field coil 103 generates heat, and the temperature of the iron shim 103e is affected by the heat generated by the gradient magnetic field coil 103. Be raised. Therefore, preheating can be performed without relying on the cooling system 200.

  A flow of processing (condition reception processing) for receiving various conditions when setting the protocol execution mode, which is executed by the MRI apparatus 100 according to the present embodiment, will be described. FIG. 4 is a diagram illustrating an example of the flow of condition reception processing. FIG. 5 is a diagram illustrating an example of a condition setting screen. For example, when receiving an instruction to set various conditions from the operator via the input circuit 134, the reception function 133a executes a condition reception process illustrated in the example of FIG.

  As shown in the example of FIG. 4, the reception function 133a displays the condition setting screen 20 shown in the example of FIG. 5 on the display 135 (step S101).

  The condition setting screen 20 includes a check box 20a, a text box 20b, a check box 20c, a button 20d, and a button 20e. The check box 20f and the check box 20g are displayed on the display 135 in a state where the check box 20f and the check box 20g can be checked only when the check box 20c is checked.

  The check box 20a is for selecting a wake-up heat mode. For example, when the operator operates the input circuit 134 and checks the check box 20a, the wake-up heat mode is selected.

  Here, the wake-up heat mode is, for example, when the power switch of the MRI apparatus 100 is turned on and the MRI apparatus 100 is activated, because the temperature of the iron shim 103e is low when the MRI apparatus 100 is activated. It refers to a mode in which preheating is performed to raise the temperature. For example, in the wake-up heat mode, when there is sufficient time until the protocol is first executed after the MRI apparatus 100 is activated, the temperature of the iron shim 103e is increased to the saturation temperature of the protocol to be executed. be able to.

  In the text box 20b, when preheating or the above-described waiting control is performed, an upper limit value (maximum heat time or maximum cooling time) from the start to the end of the preheating or waiting control is input via the input circuit 134. Input from the operator. Here, the time from the start of preheat or wait control to the end is also the time from the start of preheat or wait control to the start of execution of the protocol. Therefore, for the operator, the protocol is executed. It can be said that it is time to wait. Therefore, the time from the start to the end of preheating or waiting control is also referred to as “waiting time”. Accordingly, it can be said that the maximum heat time or the maximum cooling time is an upper limit value of the waiting time. The upper limit value of the waiting time is also referred to as the maximum waiting time. For example, if the operator thinks that preheating or waiting control may be performed if the preheating or waiting control time is 60 seconds or less, “60” is set as the maximum waiting time in the text box 20b. Enter.

  The check box 20c is for selecting the protocol order automatic change mode. For example, when the operator operates the input circuit 134 and checks the check box 20c, the protocol order automatic change mode is selected.

  Here, the protocol order automatic change mode is a mode in which, for example, the order of execution of a plurality of protocols executed in the inspection to be performed is changed.

  When the check box 20c is checked, the check box 20f and the check box 20g can be checked by the operator as shown in the example of FIG. Here, the check box 20f cannot be checked when the check box 20g is checked. Also, the check box 20g cannot be checked when the check box 20f is checked. Therefore, the operator can check only one of the check box 20f and the check box 20g via the input circuit 134. In the example of FIG. 5, a case where the check box 20f is checked is shown.

  The check box 20f is for selecting a mode that prioritizes the image quality of the reconstructed image. The check box 20g is for selecting a mode in which priority is given to shortening the waiting time.

  The button (setting button) 20 d is written as “setting”, and is a button for setting various conditions input to the condition setting screen 20 to setting information stored in the storage circuit 132.

  The button (cancel button) 20 e is written as “cancel” and is a button for closing the condition setting screen 20.

  The reception function 133a determines whether or not the cancel button 20e is pressed by the operator via the input circuit 134 (step S102). When the cancel button 20e is pressed (step S102; Yes), the reception function 133a closes the condition setting screen 20 (step S105) and ends the condition reception process.

  On the other hand, when the cancel button 20e is not pressed (step S102; No), the reception function 133a determines whether or not the setting button 20d is pressed by the operator via the input circuit 134 (step S103). . When the setting button 20d is pressed (step S103; Yes), the reception function 133a selects the information indicating whether or not the wake-up heat mode is selected, the maximum waiting time, and the protocol order automatic change mode. Information indicating whether or not, and information indicating which mode was selected from among the modes that prioritize the image quality when the protocol order automatic change mode is selected or the modes that prioritize the reduction of the waiting time is set as the setting information. (Step S104), the process proceeds to Step S105. Moreover, the reception function 133a returns to step S102, when the setting button 20d is not pressed (step S103; No). The flow of condition reception processing has been described above.

  Steps S101 to S105 are steps corresponding to the reception function 133a. This is a step in which the reception function 133a is realized by the processing circuit 133 reading and executing a predetermined program corresponding to the reception function 133a from the storage circuit 132.

  Further, the reception function 133a receives, as an imaging condition, a protocol group to be executed in the examination to be performed and parameters of each protocol included in the protocol group from the operator, and stores the received imaging condition in the storage circuit 132. To set the imaging condition.

  For example, the reception function 133a displays an imaging condition setting screen for receiving imaging conditions on the display 135, and receives input of imaging conditions by an operator via the input circuit 134. The reception function 133a stores the received imaging condition in the storage circuit 132 and generates sequence information according to the received imaging condition. That is, the reception function 133a sets a protocol group selected from a plurality of protocol groups preset in the storage circuit 132 as a protocol group scheduled to be executed in the examination to be performed. The reception function 133a also sets various parameters such as an execution time set by the operator as imaging conditions.

  In the present embodiment, for example, one or more protocols are set when performing one inspection. Further, in one protocol, for example, imaging according to one pulse sequence is performed.

  With reference to FIG. 6A and FIG. 6B, a flow of processing (imaging control processing) performed by the MRI apparatus 100 according to the present embodiment that receives imaging conditions and performs imaging based on the received imaging conditions will be described. 6A and 6B are diagrams illustrating an example of the flow of imaging control processing. FIG. 7 is a diagram illustrating an example of an imaging condition setting screen in the embodiment. For example, when the reception function 133a receives an instruction to perform an inspection from the operator via the input circuit 134, the reception function 133a executes the imaging control process illustrated in the examples of FIGS. 6A and 6B.

  For example, as illustrated in the examples of FIGS. 6A and 6B, the reception function 133a displays the imaging condition setting screen 30 illustrated in the example of FIG. 7 on the display 135 (step S201). The imaging condition setting screen 30 includes an area 31, an area 32, and an area 33 in order from the left. In the region 31, a human body model diagram that accepts selection for each imaging region is displayed. In the area 32, a list of generic names of a set of imaging protocols (protocol group) set in advance for the imaging part selected in the area 31 is displayed. In the area 33, a list of protocols included in the protocol group selected in the area 32 is displayed together with parameters of each protocol. On the display screen 30, the operator selects a desired protocol to be executed in the examination to be performed by selecting, for example, the region 31, the region 32, and the region 33 in this order according to the hierarchical structure.

  For example, when the operator selects a rectangle corresponding to “chest” on the area 31, a list of generic names of protocol groups related to “chest” is displayed in the area 32. Subsequently, when the operator selects “Breast + Fatsat”, which is a generic name of a protocol group for imaging the chest with fat suppression, in the area 32, a list of protocols included in the protocol group is displayed in the area 33. Is displayed. This list includes one or a plurality of imaging scan protocols for collecting image data of an output image and preparation scans performed for preparation of imaging scan and image generation. For example, the preparation scanning protocol includes a protocol for collecting a positioning image, a protocol for collecting a sensitivity map, a protocol for shimming, and the like. In addition, initial values are set for the parameters included in each protocol. Here, for example, when the operator selects a desired protocol from the list displayed in the area 33, a window for inputting parameters of the selected protocol is displayed. The operator inputs an execution time or the like as a parameter of the selected protocol into the window via the input circuit 134. Thus, the protocol group is provided as preset information. With the method described above, the operator inputs imaging conditions for each examination.

  And the reception function 133a receives the imaging condition for every test | inspection input by the operator, and sets the received imaging condition (step S202). Here, each protocol of the protocol group included in the set imaging condition is taken out in order, and imaging and the like for collecting various data according to the taken-out protocol are performed.

  Then, the setting function 133b sets the execution mode of the protocol based on the temperature change model indicating the temporal change in the temperature of the iron shim 103e when the protocol is executed. The temporal change in the temperature of the iron shim 103e when a certain protocol is executed is substantially the same as the temporal change in the temperature of the gradient magnetic field coil 103 when the same protocol is executed. For this reason, the MRI apparatus 100 uses a temperature change model showing a temporal change in the temperature of the iron shim 103e when a certain protocol is executed as a temporal change in the temperature of the gradient magnetic field coil 103 when this protocol is executed. Can be treated as a temperature change model. The setting function 133b is an example of a setting unit described in the claims.

  A method for setting the protocol execution mode by the setting function 133b will be described with a specific example. The setting function 133b refers to the setting information stored in the storage circuit 132, and determines whether or not the protocol order automatic change mode has been selected by the operator (step S203).

  When the protocol order automatic change mode is not selected by the operator (step S203; No), the reception function 133a interfaces with a signal indicating the current temperature (current temperature) of the iron shim 103e detected by the temperature sensor 140. The current temperature of the iron shim 103e acquired by the circuit 131 and indicated by the acquired signal is acquired (step S204).

  The setting function 133b selects one protocol to be executed earliest from the present among the unselected protocols to be executed included in the imaging conditions set in step S202 (step S205).

  Then, the setting function 133b predicts the temperature of the iron shim 103e when the execution of the selected protocol is completed (step S206). Here, an example of such a temperature prediction method will be described. For example, a temperature change model indicating a temporal change in the temperature of the iron shim 103e when the protocol is executed is uniquely determined depending on the type of the protocol. The temperature change model includes a temperature increase model and a temperature decrease model. For example, when the temperature of the iron shim 103e is lower than the saturation temperature of the protocol, the temperature increase model is a model that shows a change in which the temperature of the iron shim 103e when the protocol is executed increases with time. The temperature decrease model is a model showing a change in which the temperature of the iron shim 103e when the protocol is executed decreases with time when the temperature of the iron shim 103e is higher than the saturation temperature of the protocol.

FIG. 8 shows a slice gradient magnetic field G _SS , a phase encoding gradient magnetic field G _PE and a read gradient magnetic field when current is supplied to each of the three coils forming the gradient magnetic field coil 103 by executing the protocol. It is a figure which shows an example of the time change of each magnetic field intensity of _GRO . FIG. 9 is a diagram illustrating an example of a temperature rise model. FIG. 10 is a diagram illustrating an example of a temperature decrease model.

For example, as shown in the example of FIG. 8, the setting function 133 b includes a waveform of current supplied to each of the three coils forming the gradient coil 103 in order to change the magnetic field strength with time, and TR (Repetition Time). ) And a temperature increase model represented by the following equation (1) as shown in the example of FIG. 9 is derived by a known method.
T = T _max (1−exp (−t / τ)) (1)

Here, T _max represents a saturation temperature, τ represents a time constant, t represents time, and T represents the temperature of the iron shim 103e at time t. That is, the setting function 133b calculates T _max and τ based on the waveforms of the currents supplied to the three coils G _SS , G _PE , and G _RO and TR, thereby obtaining the above formula (1 ) Is derived.

Further, the setting function 133b derives a temperature decrease model as shown in the example of FIG. 10 by a known method. In addition, _Tmin in the example of FIG. 10 is a temperature comparable to _Tmax mentioned above, and is a lower limit of the temperature of the iron shim 103e in a temperature fall model.

Then, the setting function 133b refers to the imaging conditions stored in the storage circuit 132 and acquires the execution time of the selected protocol. Then, when the current temperature of the iron shim 103e is equal to or lower than the saturation temperature (T _max ) in the selected protocol, the setting function 133b uses the current temperature of the iron shim 103e in the temperature increase model represented by the above equation (1). From the time corresponding to the temperature, the temperature T when the acquired protocol execution time is advanced is predicted as the temperature of the iron shim 103e when the execution of the protocol is completed.

  In addition, when the current temperature of the iron shim 103e is higher than the saturation temperature in the selected protocol, the setting function 133b determines the protocol of the acquired protocol from the time corresponding to the current temperature of the iron shim 103e in the derived temperature decrease model. The temperature T when the execution time is advanced is predicted as the temperature of the iron shim 103e when the execution of the protocol is completed.

  Then, the setting function 133b determines whether or not the absolute value of the difference between the predicted temperature of the iron shim 103e (predicted temperature) and the acquired current temperature of the iron shim 103e is equal to or smaller than a predetermined value α (step). S207). As such a predetermined value α, for example, the maximum value of the absolute value of the difference between the predicted temperature and the current temperature within a range in which deterioration of the image quality of the reconstructed image can be allowed is employed. .

  That is, when the absolute value of the difference between the predicted temperature and the current temperature is less than or equal to the predetermined value α, the image quality of the reconstructed image is in an acceptable range, so the temperature of the iron shim 103e due to preheating is increased. The imaging can be performed by executing the selected protocol without waiting for the waiting time due to the control to reduce the temperature of the iron shim 103e by the cooling system 200 (the above-described waiting control).

  If the absolute value of the difference between the predicted temperature and the current temperature is equal to or less than the predetermined value α (step S207; Yes), the setting function 133b proceeds to step S212. On the other hand, when the absolute value of the difference between the predicted temperature and the current temperature is greater than the predetermined value α (step S207; No), the setting function 133b calculates a temperature change coefficient (step S208).

  Here, a specific method for calculating the temperature change coefficient will be described. The temperature change coefficient includes a temperature increase coefficient and a temperature decrease coefficient. For example, the setting function 133b calculates a temperature increase coefficient as a temperature change coefficient when the current temperature of the iron shim 103e is equal to or lower than the saturation temperature in the selected protocol. FIG. 11 is a diagram for explaining an example of a method for calculating a temperature increase coefficient. In the example of FIG. 11, an example of the temperature increase model of the selected protocol is shown. For example, when the current temperature of the iron shim 103e is equal to or lower than the saturation temperature in the selected protocol and the current temperature of the iron shim 103e is 22 degrees, the setting function 133b increases the temperature as shown in the example of FIG. In the model, the temperature “40 ° C.” is specified when the time advances by 3 time phases from the time corresponding to 22 ° C. One time phase corresponds to the timing at which an image is reconstructed.

  Then, the setting function 133b calculates the temperature “18 degrees” by subtracting the current temperature “22 degrees” from the specified temperature “40 degrees”. Then, the setting function 133b divides the calculated “18 degrees” by “3 time phases” and calculates a temperature change “6 degrees” per time phase as a temperature increase coefficient. In addition, although the example in which the setting function 133b specifies the temperature when the time has advanced by three time phases from the current temperature when calculating the temperature increase coefficient has been described, the three time phases from the time corresponding to the current temperature have been described. The temperature when the time has advanced by a predetermined number of time phases other than the above may be specified.

  The setting function 133b calculates a temperature decrease coefficient as a temperature change coefficient when the current temperature of the iron shim 103e is higher than the saturation temperature. For example, the setting function 133b specifies the temperature when the time advances by a predetermined number of time phases from the time corresponding to the current temperature in the temperature decrease model. Then, the setting function 133b calculates (specified temperature−current temperature) by subtracting the current temperature from the specified temperature. Then, the setting function 133b divides the calculated (specified temperature−current temperature) by the predetermined number of time phases described above, and calculates a change in temperature per time phase as a temperature decrease coefficient.

  Next, the setting function 133b determines whether or not the calculated absolute value of the temperature change coefficient is equal to or less than a predetermined value β (step S209). As such a predetermined value β, for example, the maximum value of the absolute value of the temperature change coefficient in the range in which the deterioration of the image quality of the reconstructed image can be allowed is employed. For example, in the example of FIG. 11, the temperature “57 degrees” of the iron shim 103 e is subtracted from the time corresponding to the temperature “62 degrees” by the temperature “57 degrees” corresponding to the time three hours earlier. The case where “5 degrees” is calculated, and the temperature change “1.67 degrees” per one time phase obtained by dividing the calculated temperature “5 degrees” by “3 time phases” is set as the predetermined value β is shown. .

  That is, when the absolute value of the difference between the predicted temperature and the current temperature is larger than the predetermined value α and the absolute value of the temperature change coefficient is larger than the predetermined value β, the image quality of the reconstructed image can be allowed to deteriorate. Since it is not within the range, it is considered necessary to perform control for increasing the temperature of the iron shim 103e by preheating or the above-described waiting control.

  When the absolute value of the temperature change coefficient is equal to or less than the predetermined value β (step S209; Yes), the setting function 133b proceeds to step S212. On the other hand, when the absolute value of the temperature change coefficient is larger than the predetermined value β (step S209; No), the setting function 133b calculates the optimum time (step S210).

Here, a specific calculation method of the optimum time will be described. The optimum time includes an optimum preheating time and an optimum cooling time. For example, when the current temperature of the iron shim 103e is equal to or lower than the saturation temperature in the selected protocol, the setting function 133b calculates an optimal preheat time as the optimal time. FIG. 12 shows an example of a preheat temperature rise model showing temporal changes in the temperature of the iron shim 103 e when a preheating current is supplied to each of the three coils forming the gradient magnetic field coil 103. Note that the preheat temperature increase model also shows temporal changes in the temperature of the gradient magnetic field coil 103 when a preheating current is supplied to each of the three coils. The preheat temperature rise model is an example of a temperature change model described in the claims. As shown in the example of FIG. 12, in the preheat temperature rise model, the temperature of the iron shim 103e approaches the temperature T _{max_heat} as time elapses. For example, in the example of FIG. 12, the time corresponding to the current temperature of the iron shim 103e is t1, and the change in temperature per time phase from the time t2 to the time t3 is the predetermined value β described above. explain. The time t3 is a time advanced from the time t2 by three time phases. In this case, the setting function 133b predicts a time t _heat between the time t2 and the time t1 as a candidate for the optimum preheat time. That is, the setting function 133b predicts a candidate for the optimal preheat time based on the preheat temperature rise model.

Then, the setting function 133b refers to the setting information stored in the storage circuit 132, and compares the time t _heat that is a candidate for the optimal preheat time with the maximum heat time indicated by the setting information. Then, the setting function 133b sets the maximum heat time as the optimum preheat time when the time t _heat is equal to or longer than the maximum heat time. On the other hand, setting function 133b, the time _{t heat} is the case is less than the maximum heat time, the optimum preheat time period _{t heat.} In this way, the setting function 133b calculates the optimal preheat time as the optimal time.

  That is, the setting function 133b calculates a time equal to or less than the maximum heat time that is the upper limit value of the waiting time for the operator as the optimum preheat time. In addition, based on the temperature increase model of the selected protocol, the setting function 133b sets the protocol execution mode so that preheating is performed for a time equal to or less than the maximum heat time accepted by the acceptance function 133a. To do. In addition, from the above, the setting function 133b seems to perform preheating only for the maximum heat time when the time indicated by the predicted optimum preheat time candidate is equal to or longer than the maximum heat time received by the reception function 133a. To set the protocol execution mode. In addition, from the above, the setting function 133b, when the predicted optimum preheat time candidate is less than the maximum heat time accepted by the acceptance function 133a, preheats only the time indicated by the predicted optimum preheat time candidate. The mode of protocol execution is set so that

For example, the setting function 133b calculates the optimal cooling time as the optimal time when the current temperature of the iron shim 103e is higher than the saturation temperature in the selected protocol. FIG. 13 shows a case where the supply of current to each of the three coils forming the gradient magnetic field coil 103 is stopped and the gradient magnetic field coil 103 is cooled by the water that is constantly supplied to the gradient magnetic field coil 103 by the cooling system 200. An example of the cooling temperature fall model which shows the time change of the temperature of this iron shim 103e is shown. The cooling temperature decrease model also shows a temporal change in the temperature of the gradient coil 103 when the gradient coil 103 is cooled. The cooling temperature decrease model is an example of a temperature change model described in the claims. As shown in the example of FIG. 13, in the cooling temperature decrease model, the temperature of the iron shim 103e approaches the temperature _{Tmin_cool} as time elapses. For example, in the example of FIG. 13, the time corresponding to the current temperature of the iron shim 103e is t4, and the absolute value of the change in temperature per time phase from the time t5 to the time t6 is the predetermined value β described above. A case will be described. The time t6 is a time advanced from the time t5 by three time phases. In this case, the setting function 133b predicts a time t _cool between the time t5 and the time t4 as a candidate for the optimal cooling time. That is, the setting function 133b predicts a candidate for the optimal cooling time based on the cooling temperature decrease model.

Then, the setting function 133b refers to the setting information stored in the storage circuit 132, and compares the time t _cool that is a candidate for the optimum cooling time with the maximum cooling time indicated by the setting information. The setting function 133b sets the maximum cooling time as the optimal cooling time when the time t _cool is equal to or longer than the maximum cooling time. On the other hand, when the time t _cool is less than the maximum cooling time, the setting function 133b sets the time t _cool as the optimal cooling time. In this way, the setting function 133b calculates the optimum cooling time as the optimum time.

  That is, the setting function 133b calculates a time equal to or less than the maximum cooling time that is the upper limit value of the waiting time for the operator as the optimum cooling time. In addition, from the above, the setting function 133b sets the protocol execution mode so that the waiting control is performed for a time equal to or shorter than the maximum cooling time accepted by the acceptance function 133a based on the cooling temperature decrease model. In addition, from the above, the setting function 133b allows the protocol so that cooling is performed only for the maximum cooling time when the predicted optimum cooling time candidate is equal to or greater than the maximum cooling time received by the reception function 133a. Set the execution mode. In addition, from the above, the setting function 133b indicates the predicted optimum cooling time candidate when the time indicated by the predicted optimum cooling time candidate is less than the maximum cooling time accepted by the acceptance function 133a. The mode of execution of the protocol is set so that cooling is performed only for the time.

  Then, the setting function 133b controls the sequence control circuit 120 so as to perform preheating only for the optimum time, or waits without doing anything for the optimum time, and the gradient magnetic field generated by the cooling system 200 that is always operating. Control is performed so that only the coil 103 is cooled (step S211). For example, when the current temperature of the iron shim 103e is equal to or lower than the saturation temperature in the selected protocol, the setting function 133b has a preheating current corresponding to the optimum time for each of the three coils forming the gradient coil 103. The supplied sequence information is generated, and the generated sequence information is transmitted to the sequence control circuit 120.

For example, when the current temperature of the iron shim 103e is higher than _Tmax , the setting function 133b waits without doing anything for the optimum time. Here, the cooling system 200 cools the gradient magnetic field coil 103 regardless of the operation of the MRI apparatus 100. For this reason, the gradient magnetic field coil 103 is cooled by the cooling system 200 even when waiting for the optimum time without doing anything.

  Then, the setting function 133b controls the sequence control circuit 120 so as to execute the selected protocol (step S212). For example, the setting function 133b generates sequence information using the selected protocol and the parameters of the selected protocol, and transmits the generated sequence information to the sequence control circuit 120. Thereby, the sequence control circuit 120 performs imaging based on the sequence information. That is, the sequence control circuit 120 executes the protocol selected by the setting function 133b in accordance with the protocol mode set by the setting function 133b.

  The setting function 133b refers to the correspondence table between the temperature of the iron shim 103e and the deviation of the center frequency of the RF pulse from the reference frequency when generating the sequence information, and the execution of the protocol predicted in step S206 is completed. The center frequency is corrected using the deviation from the reference frequency of the center frequency corresponding to the temperature of the iron shim 103e at the time, and sequence information is generated using the corrected center frequency. Here, the correspondence table is stored in the storage circuit 132 in advance.

  Then, the setting function 133b determines whether or not there is an unselected protocol among the execution target protocols included in the imaging condition set in step S202 (step S213). If there is no unselected protocol (step S213; No), the setting function 133b ends the imaging control process.

  On the other hand, when there is an unselected protocol (step S213; Yes), the setting function 133b returns to step S204 and performs the same process for the protocol to be executed next. Then, the setting function 133b performs the above-described processing for all protocols. As a result, before execution, it is determined whether or not to perform preheating or waiting control for the optimal time for all protocols, and control according to the determination result is performed.

  FIG. 14 is a diagram illustrating an example of a result of executing steps S204 to S213 in FIG. 6A. In the example of FIG. 14, three protocols executed in one examination and parameters of each protocol are set as imaging conditions in step S202, and time t and iron shim 103e as a result of executing steps S204 to S213. The graph which shows the relationship with the temperature T of is shown.

  As shown in the graph of FIG. 14, the first protocol to be executed out of the three protocols is executed from time t8 to time t9, but before this protocol is executed, the time from time t7 to time t8 is executed. Preheating is performed for time t14 minutes. Since preheating is performed in this way, the temperature of the iron shim 103e at the start of execution of the first protocol and the iron shim 103e at the time of completion of execution of the first protocol are compared with the case where preheating is not performed. The difference with temperature becomes smaller. Therefore, the change in the magnetic permeability of the iron shim 103e due to the change in temperature is also reduced, and the fluctuation of the center frequency of the RF pulse is reduced. Therefore, obstruction of fat suppression and occurrence of artifacts in the image can be suppressed. Therefore, it is possible to suppress the deterioration of the image quality of the image. That is, it is possible to suppress the image quality influence on the imaging due to the temporal change in the temperature of the iron shim 103e.

  And time t14 when preheating is performed is time below the maximum heat time set by the operator. That is, the preheating time is at most the maximum heating time. Thereby, it can suppress that the time of preheating increases. For this reason, it is possible to suppress the occurrence of a situation in which the operator feels that the time from the start of the examination until the imaging is performed by executing the protocol is long. That is, the temporal influence on the imaging due to the temporal change of the temperature of the iron shim 103e can be suppressed. In addition, temporal influence on imaging due to temporal change in the temperature of the gradient magnetic field coil 103 can be suppressed.

  As shown in the graph of FIG. 14, the second protocol to be executed is executed from time t10 to time t11, and the third protocol to be executed is executed from time t12 to time t13. Then, before the second protocol is executed, preheating is performed for time t15 from time t9 to time t10. Further, before the third protocol is executed, preheating is performed for time t16 from time t11 to time t12. Therefore, also in this case, it is possible to suppress the deterioration of the image quality of the image. That is, it is possible to suppress the image quality influence on the imaging due to the temporal change in the temperature of the iron shim 103e.

  And time t15 and t16 when preheating is performed are time below the maximum heat time set by the operator. Therefore, also in this case, the time during which preheating is performed is the maximum heat time at the longest. Thereby, also in this case, it can suppress that the time of preheating increases. In addition, it is possible to suppress the occurrence of a situation in which the operator feels that the time from the start of the examination until the imaging is performed by executing the protocol is long. That is, the temporal influence on the imaging due to the temporal change of the temperature of the iron shim 103e can be suppressed.

  Returning to the description of FIG. 6A, when the protocol order automatic change mode is selected by the operator (step S203; Yes), the setting function 133b refers to the setting information stored in the storage circuit 132 and prioritizes image quality. It is determined which mode has been selected by the operator from among the modes to be performed or the modes in which priority is given to shortening the waiting time (step S214).

  When the operator has selected a mode that prioritizes image quality (step S214; image quality), the setting function 133b selects from the unselected examinations to be executed that are included in the imaging conditions set in step S202. Then, one test that is performed earliest from the present is selected (step S215).

  Then, the setting function 133b selects a plurality of protocols to be executed in the selected examination (Step S216).

  Next, the setting function 133b predicts the temperature of the iron shim 103e when executed independently for each of the selected protocols (step S217). For example, for each of a plurality of selected protocols, the setting function 133b starts execution of the protocol when the temperature of the iron shim 103e is a predetermined reference temperature (for example, 20 degrees), and the execution time indicated by the imaging condition. Only the protocol is executed, and the temperature of the iron shim 103e at the time when the execution of the protocol is completed is predicted.

  Here, an example of such a temperature prediction method will be described. For example, the setting function 133b derives the temperature rise model for each of the selected protocols by the same method as the temperature rise model derivation method described above. Then, for each of the plurality of selected protocols, the setting function 133b uses the temperature T when the temperature rise model advances from the time corresponding to the predetermined reference temperature of the iron shim 103e by the execution time of the protocol indicated by the imaging condition. Is estimated as the temperature of the iron shim 103e when the execution of the protocol is completed. In this way, the setting function 133b predicts the temperature of the iron shim 103e when executed independently for each of the selected protocols.

  Then, the setting function 133b rearranges the selected plurality of protocols in the ascending order of the predicted temperature (step S218). Then, the setting function 133b controls the sequence control circuit 120 so that the protocols are executed in the rearranged order (step S219). For example, the setting function 133b generates sequence information for each of a plurality of selected protocols by using the protocol, the order in which the protocol is executed, and parameters of the protocol. The sequence information thus transmitted is transmitted to the sequence control circuit 120. Thereby, the sequence control circuit 120 performs imaging based on the sequence information. Note that when generating the sequence information, the setting function 133b predicts the temperature of the iron shim 103e when the execution of each protocol is completed, and corresponds to the temperature predicted for each protocol by referring to the correspondence table described above. The center frequency is corrected using the deviation of the center frequency from the reference frequency, and sequence information is generated using the corrected center frequency.

  From the above, the setting function 133b determines the order in which the plurality of protocols are executed based on the respective temperature increase models of the plurality of protocols, and sets the plurality of protocols so that the plurality of protocols are executed in the determined order. Sets the protocol execution mode. In addition, from the above, the sequence control circuit 120 executes a plurality of protocols according to the execution mode of the plurality of protocols set by the setting function 133b.

  In addition, from the above, the setting function 133b predicts the temperature of the iron shim 103e when the protocol is executed for each of the plurality of protocols based on the temperature increase model of each of the plurality of protocols. The execution mode of a plurality of protocols is set so that the protocols are executed in order from the lowest temperature.

  Then, the setting function 133b determines whether or not there is an unselected inspection among the inspections included in the imaging conditions set in Step S202 (Step S220). If there is an unselected examination (step S220; Yes), the setting function 133b returns to step S215. On the other hand, when there is no unselected examination (step S220; No), the setting function 133b ends the imaging control process.

  FIG. 15 shows an example of a result when the protocols are executed in the same order set as the photographing conditions in step S202 and a result when the order of the protocols to be executed is rearranged by executing steps S215 to S220. FIG.

  The graph shown on the upper side of FIG. 15 will be described. The graph shown on the upper side of FIG. 15 shows the time t and the temperature T of the iron shim 103e when the three protocols set as the imaging conditions are executed without rearranging the order of the protocols set as the imaging conditions in step S202. An example of the relationship is shown. Here, in step S202, when the three protocols executed in one examination are executed independently, the order in which the iron shim 103e is executed in descending order when the execution is completed. Is set as the imaging condition.

  As shown in the upper graph of FIG. 15, among the three protocols, the protocol A having the highest temperature of the iron shim 103 e at the time when the execution alone is completed is executed from the time t17 to the time t18. The Of the three protocols, the protocol B whose temperature of the iron shim 103e is the second highest after the protocol A at the time when the execution alone is completed is executed from the time t18 to the time t19. Then, among the three protocols, the protocol C having the lowest temperature of the iron shim 103e at the time when the execution alone is completed is executed from the time t19 to the time t20.

  From the upper graph of FIG. 15, the difference between the temperature of the iron shim 103e at the time t17 when the execution of the protocol A is started and the temperature of the iron shim 103e at the time t18 when the execution of the protocol A is completed is You can see that it ’s big. Therefore, when the protocol A is a protocol that performs many imaging during the execution, the center frequency of the RF pulse in the imaging just before the start of the execution of the protocol and the RF pulse at the time just before the completion of the protocol execution. The difference between the center frequency and the image quality of the reconstructed image deteriorates. For example, when the protocol A is fMRI (functional magnetic resonance imaging) in which the saturation temperature is about 55 ° C., the execution time is about 20 minutes, and one image is taken every 2 seconds, the image The image quality will deteriorate.

  Therefore, in the present embodiment, when a mode that prioritizes image quality is selected by the operator, a plurality of protocols are rearranged in the ascending order of predicted temperatures in order to suppress deterioration in image quality.

  The lower part of FIG. 15 shows the relationship between the time t and the temperature T of the iron shim 103e when the order of protocol A, protocol B, and protocol C is rearranged and executed in the order of protocol C, protocol B, and protocol A. The graph which shows is shown.

  As shown in the lower graph of FIG. 15, protocol C is executed from time t17 to time t22. Protocol B is executed from time t22 to time t23. Then, protocol A is executed from time t24 to time t25.

Here, when the execution of the protocol B is completed, the execution of the protocol A is not started immediately, but the execution of the protocol A is started after waiting for the time t26 from the time t23 to the time t24. The reason for this will be described. For example, when the execution of the protocol B is completed, the temperature of the iron shim 103e is high, and the protocol A is immediately executed for the execution time of the protocol A without providing the cooling period of the gradient coil 103. If this happens, the allowable temperature T _t of the MRI apparatus 100 may be exceeded.

Therefore, the setting function 133b calculates a time t26 which is a waiting time, waits for only the time t26 minutes after the execution of the protocol B is completed, and then the gradient coil 103 by the cooling system 200 that is always operating. Control is performed so that only cooling is performed. That is, the setting function 133b generates sequence control information for executing each protocol at the timing shown in the lower graph of FIG. 15 and transmits the generated sequence control information to the sequence control circuit 120. Thereby, although the waiting time t26 occurs, the deterioration of the image quality of the image can be suppressed without exceeding the allowable temperature T _t of the MRI apparatus 100. That is, it is possible to suppress the image quality influence on the imaging due to the temporal change in the temperature of the iron shim 103e.

Here, an example of a method for calculating the waiting time t26 will be described. For example, the setting function 133b first acquires the current temperature of the iron shim 103e (gradient magnetic field coil 103). Then, the setting function 133b sets the temperature T _start at the _start of execution of the protocol A when the allowable temperature T _t is not exceeded even if it is executed for the execution time of the protocol A indicated by the imaging condition in the temperature rise model of the protocol A. Identify. Then, in the cooling temperature decrease model, the setting function 133b calculates a time from the time corresponding to the current temperature of the gradient magnetic field coil 103 to the time corresponding to the temperature T _start as a waiting time candidate.

Then, the setting function 133b refers to the setting information stored in the storage circuit 132, and compares the waiting time candidate with the maximum cooling time indicated by the setting information. The setting function 133b sets the maximum cooling time as the waiting time t26 when the waiting time candidate is equal to or longer than the maximum cooling time. On the other hand, when the waiting time candidate is less than the maximum cooling time, the setting function 133b sets the waiting time candidate as the waiting time t26. In this way, the setting function 133b calculates the waiting time t26 based on the cooling temperature decrease model, and sets the protocol execution mode in which the protocol A is executed after waiting for the waiting time t26 from the time t23. In other words, the setting function 133b determines that the temperature of the gradient magnetic field coil 103 is the predetermined allowable temperature when the protocol A to be executed is executed for the execution time of the predetermined protocol A indicated by the imaging condition based on the cooling temperature decrease model. Control is performed to reduce the temperature of the gradient magnetic field coil 103 by a waiting time t26 when it does not exceed _{Tt, and} for a waiting time equal to or shorter than the execution time of the control for reducing the temperature of the gradient magnetic field coil 103 received by the reception function 133a. Set the mode of execution of Protocol A to be performed.

  Returning to the description of FIG. 6A, when the mode in which priority is given to shortening the waiting time is selected by the operator (step S214; waiting time), the setting function 133b is set in step S202 as shown in FIG. 6B. From the unselected examinations to be executed included in the imaging conditions, one examination that is performed earliest from the present is selected (step S221).

  Then, the setting function 133b selects a plurality of protocols to be executed in the selected examination (Step S222).

  Next, the setting function 133b predicts the temperature of the iron shim 103e when it is executed independently for each of the selected plurality of protocols, similarly to step S217 (step S223).

  Then, the setting function 133b rearranges the selected protocols in descending order of the predicted temperature (step S224). Then, as in step S219, the setting function 133b generates sequence information that executes the protocols in the rearranged order, and transmits the generated sequence information to the sequence control circuit 120 to control the sequence control circuit 120. (Step S225). Thereby, the sequence control circuit 120 performs imaging based on the sequence information. The setting function 133b, when generating the sequence information, corrects the center frequency by the same method as described above, and generates the sequence information using the corrected center frequency.

  From the above, the setting function 133b determines the order in which the plurality of protocols are executed based on the respective temperature increase models of the plurality of protocols, and sets the plurality of protocols so that the plurality of protocols are executed in the determined order. Sets the protocol execution mode. In addition, from the above, the sequence control circuit 120 executes a plurality of protocols according to the execution mode of the plurality of protocols set by the setting function 133b.

  In addition, from the above, the setting function 133b predicts the temperature of the iron shim 103e when the protocol is executed for each of the plurality of protocols based on the temperature increase model of each of the plurality of protocols. The execution mode of a plurality of protocols is set so that the protocols are executed in order from the protocol with the highest temperature.

  Then, the setting function 133b determines whether or not there is an unselected inspection among the inspections included in the imaging conditions set in Step S202 (Step S226). If there is an unselected examination (step S226; Yes), the setting function 133b returns to step S221. On the other hand, when there is no unselected examination (step S226; No), the setting function 133b ends the imaging control process. The flow of the imaging control process that receives the imaging conditions and performs imaging based on the received imaging conditions has been described above.

  Steps S201 to S202 are steps corresponding to the reception function 133a. This is a step in which the reception function 133a is realized by the processing circuit 133 reading and executing a predetermined program corresponding to the reception function 133a from the storage circuit 132. Steps S203 to S226 are steps corresponding to the setting function 133b. This is a step in which the setting function 133b is realized by the processing circuit 133 reading and executing a predetermined program corresponding to the setting function 133b from the storage circuit 132.

  FIG. 16 shows an example of a result when the protocols are executed in the same order set as the photographing conditions in step S202 and a result when the order of the protocols to be executed is rearranged by executing steps S221 to S226. FIG.

  The graph shown on the upper side of FIG. 16 will be described. The graph shown on the upper side of FIG. 16 shows the time t and the temperature T of the iron shim 103e when the three protocols set as the imaging conditions are executed without rearranging the order of the protocols set as the imaging conditions in step S202. The relationship is shown. Here, in step S202, when three protocols executed in one examination are executed independently, the order in which the iron shims 103e are executed in ascending order when the execution is completed. Is set as the imaging condition.

  As shown in the upper graph of FIG. 16, among the three protocols, the protocol D having the lowest temperature of the iron shim 103e at the time when the execution alone is completed is executed from the time t27 to the time t28. The Further, among the three protocols, the protocol E in which the temperature of the iron shim 103e at the time when the execution alone is completed is the second lower than the protocol D is executed from the time t28 to the time t29. Of the three protocols, the protocol F having the highest temperature of the iron shim 103e at the time when the execution alone is completed is executed from the time t30 to the time t31. In the example of FIG. 16, the waiting time t32 occurs for the same reason as the waiting time t26 described in the example of FIG.

Here, it can be seen from the upper graph in FIG. 16 that when the protocol D, the protocol E, and the protocol F are executed in order, a waiting time t32 occurs, so that the entire inspection time increases. Therefore, when the protocol F has a relatively large saturation temperature and reaches the saturation temperature in a short time, the temperature of the iron shim 103e does not exceed the allowable temperature T _t of the MRI apparatus 100. As a result, a waiting time occurs, so that the entire inspection time increases. For example, if protocol F is a water-fat separation protocol in which the saturation temperature is about 80 degrees C, the execution time is about 30 seconds, and one image is captured in one execution, the protocol F Since time is generated, the time required for the entire inspection increases.

  Therefore, in this embodiment, when a mode in which priority is given to shortening the waiting time is selected by the operator, a plurality of protocols are arranged in descending order of the predicted temperature in order to suppress an increase in the time of the entire examination. Change.

  In the lower part of FIG. 16, the order of protocol D, protocol E, and protocol F is rearranged, and the relationship between time t and temperature T of iron shim 103e when executed in the order of protocol F, protocol E, and protocol D is shown. The graph which shows is shown.

  As shown in the lower graph of FIG. 16, protocol F is executed from time t27 to time t33. Protocol E is executed from time t33 to time t34. Then, protocol D is executed from time t34 to time t35.

  Here, from the lower graph of FIG. 16, the difference between the temperature of the iron shim 103e at the time t27 when the execution of the protocol F is started and the temperature of the iron shim 103e at the time t33 when the execution of the protocol F is completed. Can be seen to be large. Therefore, when the protocol F is a protocol that performs many imaging during execution, the image quality of the image is deteriorated. On the other hand, since the occurrence of the waiting time is suppressed, The increase can be suppressed. That is, the temporal influence on the imaging due to the temporal change of the temperature of the iron shim 103e can be suppressed.

  Further, when the protocol F, protocol E, and protocol D are executed in this order, if the protocol F is a protocol that performs imaging only once during execution, the center frequency of the RF pulse is shifted in the first place. Therefore, the image quality does not deteriorate. For example, when the protocol F is the above-described water fat separation method protocol, even when executed in the order of the protocol F, the protocol E, and the protocol D, deterioration in image quality of the image can be suppressed, and An increase in time of the entire inspection can be suppressed. That is, it is possible to suppress the influence on image quality and the influence on time due to the temporal change of the temperature of the iron shim 103e.

  Next, another process performed by the setting function 133b will be described. FIG. 17 is a diagram for explaining another process performed by the setting function 133b.

  For example, when the power switch of the MRI apparatus 100 is turned on and the MRI apparatus 100 is activated, the setting function 133b refers to the setting information stored in the storage circuit 132 and determines whether or not the wakeup mode is selected by the operator. judge. When the wake-up mode is selected by the operator, the setting function 133b performs preheating to increase the temperature of the iron shim 103e because the temperature of the iron shim 103e is low when the MRI apparatus 100 is started. To control.

  For example, a case will be described in which the wake-up mode is selected by the operator and the MRI apparatus 100 is activated at 8 am as shown on the left side of the example of FIG. In this case, the setting function 133b refers to the imaging condition stored in the storage circuit 132 and specifies the protocol “fMRI” that is executed earliest from the present time. Then, as shown on the right side of the example of FIG. 17, the setting function 133b performs control so that preheating is performed until 9 am when fMRI execution is started. Thereby, when the execution of fMRI is started, the temperature of the iron shim 103e is increased, so that deterioration of the image quality of the image can be suppressed. That is, it is possible to suppress the image quality influence on the imaging due to the temporal change in the temperature of the iron shim 103e.

  Also, the setting function 133b can determine whether or not the protocol to be executed is a protocol that requires preheating, and can perform preheat determination processing for controlling whether or not to perform preheating according to the determination result. . Here, the setting function 133b determines whether or not the execution target protocol is a protocol in which the difference between the temperature of the iron shim 103e at the start of execution and the temperature of the iron shim 103e at the completion of execution is greater than a predetermined value. It is possible to determine whether or not the protocol requires preheating. FIG. 18 is a diagram illustrating an example of the flow of the preheat determination process.

  Here, protocol temperature difference information is stored in the storage circuit 132 in advance. The protocol temperature difference information includes the difference between the temperature of the iron shim 103e at the start of execution and the temperature of the iron shim 103e at the completion of execution, measured in a past examination carried out in the hospital provided with the MRI apparatus 100. Are registered for each protocol type.

  As illustrated in the example of FIG. 18, the setting function 133b refers to the imaging condition stored in the storage circuit 132 and selects one protocol that is executed earliest from now (step S301).

  The setting function 133b refers to the protocol temperature difference information stored in the storage circuit 132, and the temperature of the iron shim 103e at the start of execution and the temperature of the iron shim 103e at the completion of execution corresponding to the selected protocol type. Is identified (step S302).

  Next, the setting function 133b determines whether or not the identified difference is greater than or equal to a predetermined value γ (step S303). Here, as the predetermined value γ, for example, an experimentally obtained difference between the temperature of the iron shim 103e at the start of execution of the protocol and the temperature of the iron shim 103e at the completion of execution when preheating is required The minimum value is adopted.

  If the identified difference is greater than or equal to the predetermined value γ (step S303; Yes), the setting function 133b performs control so as to execute preheating (step S304), and the preheat determination process is terminated. For example, the setting function 133b generates sequence information such that a current for preheating is supplied to each of three coils forming the gradient magnetic field coil 103, and transmits the generated sequence information to the sequence control circuit 120. The determination process ends.

  Moreover, also when the specified difference is less than predetermined value (gamma) (step S303; No), the setting function 133b complete | finishes a preheat determination process.

  That is, the setting function 133b performs preheating to increase the temperature of the iron shim 103e based on the difference between the temperature of the iron shim 103e at the start of execution and the temperature of the iron shim 103e at the completion of execution when the protocol is executed. A protocol execution mode indicating whether or not to be performed is set.

  The flow of the preheat determination process has been described above. According to the setting function 133b that executes preheat determination processing, control is performed so that preheating is performed for a protocol type that requires preheating according to the type of protocol to be executed, so that preheating can be appropriately performed. .

  Note that steps S301 to S304 are steps corresponding to the setting function 133b. This is a step in which the setting function 133b is realized by the processing circuit 133 reading and executing a predetermined program corresponding to the setting function 133b from the storage circuit 132.

  The setting function 133b can also refer to the examination reservation information stored in the storage circuit 132, identify the time when the examination is not performed, and perform preheating at the identified time. In the examination reservation information, the time period during which the examination is performed is registered for each examination.

  FIG. 19 is a diagram for explaining another process performed by the setting function 133b. As shown on the left side of the example of FIG. 19, the setting function 133b refers to the examination reservation information, and specifies a break time from 12 am to 1 pm (13:00) when no examination is performed. Then, as shown on the left side of the example in FIG. 19, the setting function 133b performs control so that preheating is executed during the specified break time.

  Here, the setting function 133b determines whether or not to perform preheating at the specified time by performing the preheat determination process described with reference to FIG. 18, and the setting function 133b performs preheating according to the determination result. You may control to perform.

  Returning to the description of FIG. 1, the display control function 133c determines the timing at which this protocol is executed according to the current temperature of the iron shim 103e, the protocol that is executed earliest from the present, and the temperature increase model of this protocol. Is displayed on the display 135. The display control function 133c is an example of a display control unit described in the claims.

  FIG. 20 is a diagram illustrating an example of information indicating the timing at which the protocol is executed, which is displayed on the display 135 by the display control function 133b. In the example of FIG. 20, a blue image, a yellow image, and a red image are displayed in each of the region 34, the region 35, and the region 36 as information indicating the timing at which the protocol is executed.

  For example, the display control function 133c refers to the imaging conditions stored in the storage circuit 132, and selects the protocol that is executed earliest from now. Then, the display control function 133c calculates an optimal preheat time. The display control function 133c calculates the optimum preheat time by the same method as the method in which the setting function 133b has calculated the optimum preheat time in step S210 of FIG.

  Then, the display control function 133c cannot immediately capture an image when the optimal preheat time is equal to or greater than the first threshold value. Therefore, as shown in the example of FIG. 20, the display control function 133c displays a red image in the region 34c. Display.

  In addition, the display control function 133c can perform imaging when the optimum preheat time is less than the first threshold and is greater than or equal to the second threshold smaller than the first threshold. As shown in the example, a yellow image is displayed in the region 34b.

  In addition, the display control function 133c displays a blue image in the region 34a as shown in the example of FIG. 20 because an image can be captured immediately when the optimal preheat time is less than the second threshold.

  Therefore, the operator can easily grasp the execution timing of the protocol simply by confirming the colors of the images displayed in the areas 34a to 34c.

  The display control function 133c executes the above-described processing every predetermined time (for example, 2 seconds), and displays information indicating the timing at which the protocol is executed on the display 135 in real time.

  The MRI apparatus 100 according to the embodiment has been described above. According to the MRI apparatus 100, as described above, it is possible to suppress an influence on imaging due to a temporal change in the temperature of the iron shim 103e.

In the example shown in the lower graph of FIG. 15, the example in which the setting function 133 b calculates the time t <b> 26 during which only cooling by the cooling system 200 is performed has been described. This is because when the execution of the protocol B is completed, the temperature of the iron shim 103e is high, and the protocol A is immediately executed for the execution time of the protocol A without providing a cooling period for the gradient coil 103. This is because there is a possibility that the allowable temperature T _t of the MRI apparatus 100 may be exceeded. However, the embodiment is not limited to this. For example, when the execution of the protocol B is completed, the setting function 133b may not execute the protocol A for the execution time of the protocol A, but may execute the protocol A for a time not exceeding the allowable temperature T _t. .

For example, in the temperature increase model of protocol A, the setting function 133b is from a time corresponding to the temperature of the iron shim 103e at the time when execution of the protocol B is completed to a time corresponding to a temperature not exceeding the allowable temperature T _t . What is necessary is just to calculate time as time which does not exceed the allowable temperature _Tt mentioned above. Then, the setting function 133b may execute the protocol A for the calculated time from the time when the execution of the protocol B is completed. As described above, the setting function 133b is executed by adjusting the time to be executed even if the protocol exceeds the allowable temperature _Tt when executed for the execution time set as the imaging condition. be able to.

  According to the magnetic resonance imaging apparatus of at least one embodiment described above, it is possible to suppress an influence on imaging due to a temporal change in the temperature of the iron shim 103e.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

100 MRI apparatus 133a reception function 133b setting function 133c display control function

Claims (11)

A gradient coil for applying a gradient magnetic field within a static magnetic field in which the subject is placed;
A derivation unit for deriving a time schedule of one examination including a series of protocol groups using a temperature change model indicating a temporal change in temperature of the gradient coil;
A sequence control unit that sequentially executes protocols included in the protocol group according to the time schedule;
A reception unit that receives input of desired conditions related to image quality from an operator;
Bei to give a,
The derivation unit is a magnetic resonance imaging apparatus that derives the time schedule according to the desired condition.   The derivation unit optimizes the waiting time between the protocol and the protocol executed immediately before the protocol by applying the imaging condition set in the protocol to the temperature change model corresponding to the protocol. The magnetic resonance imaging apparatus according to claim 1. The derivation unit determines an execution order of the protocols based on the temperature change models of the protocols included in the protocol group, and derives the time schedule so that the protocols are executed in the determined execution order. The magnetic resonance imaging apparatus according to claim 1 or 2 . A gradient coil for applying a gradient magnetic field within a static magnetic field in which the subject is placed;
A derivation unit for deriving a time schedule of one examination including a series of protocol groups using a temperature change model indicating a temporal change in temperature of the gradient coil;
A sequence control unit that sequentially executes protocols included in the protocol group according to the time schedule;
A reception unit that receives an input of an upper limit value of the waiting time from the operator;
Equipped with a,
The deriving unit, to reduce the waiting time below the upper limit value, to optimize the execution order of the protocol contained in the protocol suite, magnetic resonance imaging device. A gradient coil for applying a gradient magnetic field within a static magnetic field in which the subject is placed;
A derivation unit for deriving a time schedule of one examination including a series of protocol groups using a temperature change model indicating a temporal change in temperature of the gradient coil;
A sequence control unit that sequentially executes protocols included in the protocol group according to the time schedule;
A metal shim provided in the gradient magnetic field coil to correct spatial non-uniformity of the static magnetic field;
A reception unit that receives an upper limit value of a preheating execution time for increasing the temperature of the metal shim before the execution of the protocol is started;
Bei to give a,
The deriving unit, on the basis of the temperature change model, wherein only the upper limit or less of the time of the execution time of preheating accepted by the accepting unit preheating deriving the time scheduled to occur, magnetic resonance imaging apparatus .   The derivation unit predicts a candidate for the preheat execution time based on the temperature change model, and an upper limit of the preheat execution time accepted by the accepting unit is indicated by the predicted preheat execution time candidate If the value is equal to or greater than the value, the time schedule is derived so that the preheating is performed only for the preheat execution time received by the reception unit, and the time indicated by the predicted preheat execution time candidate is the reception unit. The time schedule is derived so that the preheating is performed only for a time indicated by the predicted preheating execution time candidate when the preheating execution time is less than the upper limit of the preheating execution time accepted by the method. Magnetic resonance imaging equipment. A gradient coil for applying a gradient magnetic field within a static magnetic field in which the subject is placed;
A derivation unit for deriving a time schedule of one examination including a series of protocol groups using a temperature change model indicating a temporal change in temperature of the gradient coil;
A sequence control unit that sequentially executes protocols included in the protocol group according to the time schedule;
A metal shim provided in the gradient magnetic field coil to correct spatial non-uniformity of the static magnetic field;
With
The derivation unit predicts the temperature of the metal shim when the protocol is executed for each of the protocols based on the temperature change model of each of the protocols included in the protocol group, and the predicted temperature is deriving the time schedule to be executed from the lower protocol in order, magnetic resonance imaging device. A gradient coil for applying a gradient magnetic field within a static magnetic field in which the subject is placed;
A derivation unit for deriving a time schedule of one examination including a series of protocol groups using a temperature change model indicating a temporal change in temperature of the gradient coil;
A sequence control unit that sequentially executes protocols included in the protocol group according to the time schedule;
A metal shim provided in the gradient magnetic field coil to correct spatial non-uniformity of the static magnetic field;
With
The derivation unit predicts the temperature of the metal shim when the protocol is executed for each of the protocols based on the temperature change model of each of the protocols included in the protocol group, and the predicted temperature is deriving the time schedule to be executed from a higher protocol order, magnetic resonance imaging device. A gradient coil for applying a gradient magnetic field within a static magnetic field in which the subject is placed;
A derivation unit for deriving a time schedule of one examination including a series of protocol groups using a temperature change model indicating a temporal change in temperature of the gradient coil;
A sequence control unit that sequentially executes protocols included in the protocol group according to the time schedule;
A metal shim provided in the gradient magnetic field coil to correct spatial non-uniformity of the static magnetic field;
With
The deriving unit calculates the temperature of the metal shim based on the difference between the temperature of the metal shim at the start of execution and the temperature of the metal shim at the completion of execution when a protocol included in the protocol group is executed. preheat to increase derives the time schedule indicating whether performed, magnetic resonance imaging device. A gradient coil for applying a gradient magnetic field within a static magnetic field in which the subject is placed;
A derivation unit for deriving a time schedule of one examination including a series of protocol groups using a temperature change model indicating a temporal change in temperature of the gradient coil;
A sequence control unit that sequentially executes protocols included in the protocol group according to the time schedule;
A metal shim provided in the gradient magnetic field coil to correct spatial non-uniformity of the static magnetic field;
With
And the temperature of the current of the metal shim, on the basis of the temperature change model comprises a display control unit for displaying the information indicating the timing for executing the protocol on the display unit, magnetic resonance imaging device. A gradient coil for applying a gradient magnetic field within a static magnetic field in which the subject is placed;
A derivation unit for deriving a time schedule of one examination including a series of protocol groups using a temperature change model indicating a temporal change in temperature of the gradient coil;
A sequence control unit that sequentially executes protocols included in the protocol group according to the time schedule;
A reception unit that receives an upper limit value of an execution time of control for lowering the temperature of the gradient coil before the execution of the protocol is started ;
With
The derivation unit predicts a candidate for the execution time of the control based on the temperature change model, and the upper limit of the execution time of the control received by the reception unit is the time indicated by the predicted candidate for the execution time of the control When the value is equal to or greater than the value, the time schedule is derived so that the control is performed only for the control execution time received by the reception unit, and the time indicated by the predicted control execution time candidate is the reception unit. When the control execution time accepted is less than the upper limit value of the control execution time, the magnetic resonance imaging apparatus derives the time schedule so that the control is performed only for the time indicated by the predicted control execution time candidate.

Images