Magnetic resonance imaging apparatus and imaging management method

Abstract

To support efficient inspection.SOLUTION: A magnetic resonance imaging apparatus according to this embodiment comprises a calculation part and an input limiting part. The calculation part calculates a limit imaging condition which is a limit permitted concerning a heat input to a superconducting magnet, on the basis of one or more imaging parameters for determining an imaging condition. The input limiting part limits an input range of the imaging parameters from an operator, on the basis of the limit imaging condition.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] In superconducting magnetic resonance imaging devices (superconducting MRI devices), helium, for example, is used as a refrigerant for the superconducting coil. However, the recent increase in the price of helium has put pressure on the lifetime cost of MRI devices. Therefore, it is desirable to adopt a low-volume refrigerant that uses as little helium as possible. With the recent focus on low-capacity refrigerants, it is necessary to take into consideration the phenomenon (GCIH: Gradient Coil Induced Heating) in which induced currents are generated in the superconducting coils in the superconducting magnet due to the application of a gradient magnetic field in imaging, causing the temperature inside the superconducting magnet to rise. In other words, in an MRI device with a large helium capacity and sufficient refrigerant, even if the temperature of the superconducting coil rises, it is highly likely that the heat can be absorbed by evaporation of the refrigerant, but if the amount of refrigerant is small, such as in the case of low-capacity refrigerants, it will not be able to handle the sudden increase in GCIH caused by imaging, and there is a high possibility that quenching will occur due to the intrusion of heat from the outside world.

[0003] Therefore, a conventional method is to predict the behavior of the magnet regarding quenching for each imaging, and if there is a high risk of quenching, to stop imaging before actually taking the image. However, after the imaging conditions are set, it is determined whether imaging is possible at the stage of performing the imaging, so if it is determined that imaging is not possible, it is necessary to reset the imaging conditions. Therefore, it may be necessary to change the conditions and take the image again, or to wait until imaging is possible, which creates a problem that imaging cannot be performed efficiently. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 8,058,873 Summary of the Invention [Problem to be solved by the invention]

[0005] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to support efficient inspection. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described later can also be positioned as other problems. [Means for solving the problem]

[0006] The magnetic resonance imaging apparatus according to the present embodiment includes a calculation unit and an input restriction unit. The calculation unit calculates a limit imaging condition that is an allowable limit for heat input to the superconducting magnet, based on one or more imaging parameters for determining the imaging condition. The input restriction unit restricts an input range of the imaging parameter from the operator, based on the limit imaging condition. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a conceptual diagram showing an MRI apparatus according to this embodiment. [Diagram 2] FIG. 2 is a flowchart showing imaging management processing of the MRI apparatus according to this embodiment. [Diagram 3] FIG. 3 is a flowchart showing details of the process of estimating the limit imaging condition according to this embodiment. [Figure 4] FIG. 4 is a conceptual diagram showing an example of calculation of the calorific value required for generating the calorific value database according to this embodiment. [Diagram 5] FIG. 5 is a diagram showing an example of a transfer function according to the present embodiment. [Figure 6] FIG. 6 is a diagram showing an example of a user interface screen according to the present embodiment. [Figure 7] FIG. 7 is a diagram showing a first display example of a user interface related to imaging parameters. [Figure 8] FIG. 8 is a diagram showing a second display example of a user interface related to imaging parameters. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, a magnetic resonance imaging apparatus (MRI apparatus) and an imaging management method according to the present embodiment will be described with reference to the drawings. In the following embodiments, parts with the same reference numerals perform similar operations, and duplicated descriptions will be omitted as appropriate.

[0009] FIG. 1 is a conceptual diagram showing an MRI apparatus according to this embodiment. 1, the MRI apparatus 1 includes a static magnetic field magnet 101, a magnet management unit 2, a gradient magnetic field coil 103, a gradient magnetic field power supply 105, a bed 107, a bed control circuit 109, a transmission circuit 113, a transmission coil 115, a reception coil 117, a reception circuit 119, a sequence control circuit 121, a bus 123, an interface 125, a display 127, a storage device 129, and a processing circuit 131. The MRI apparatus 1 may include a hollow cylindrical shim coil between the static magnetic field magnet 101 and the gradient magnetic field coil 103.

[0010] The static magnetic field magnet 101 is a magnet formed in a hollow, approximately cylindrical shape. The static magnetic field magnet 101 is not limited to an approximately cylindrical shape, and may be configured in an open shape. The static magnetic field magnet 101 generates a uniform static magnetic field in the internal space. In this embodiment, the static magnetic field magnet 101 is assumed to be a superconducting magnet using a superconducting coil.

[0011] The gradient magnetic field coil 103 is a coil formed in a hollow cylindrical shape. The gradient magnetic field coil 103 is disposed inside the static magnetic field magnet 101. The gradient magnetic field coil 103 is formed by combining three coils corresponding to the mutually orthogonal X, Y, and Z axes. The Z-axis direction is the same as the direction of the static magnetic field. The Y-axis direction is the vertical direction, and the X-axis direction is the direction perpendicular to the Z and Y axes. The three coils in the gradient magnetic field coil 103 are individually supplied with current from a gradient magnetic field power supply 105 to generate gradient magnetic fields whose magnetic field strengths change along the X, Y, and Z axes.

[0012] The gradient magnetic fields of the X, Y, and Z axes generated by the gradient coil 103 form, for example, a frequency encoding gradient magnetic field (also called a readout gradient magnetic field), a phase encoding gradient magnetic field, and a slice selection gradient magnetic field. The frequency encoding gradient magnetic field is used to change the frequency of an MR signal according to a spatial position. The phase encoding gradient magnetic field is used to change the phase of an MR signal according to a spatial position. The slice selection gradient magnetic field is used to determine an imaging cross section.

[0013] The gradient magnetic field power supply 105 is a power supply device that supplies a current to the gradient magnetic field coil 103 under the control of a sequence control circuit 121 .

[0014] The bed 107 is a device equipped with a top plate 1071 on which the subject P is placed. The bed 107 inserts the top plate 1071 on which the subject P is placed into a bore 111 under the control of a bed control circuit 109. The bed 107 is installed in an examination room in which the MRI apparatus 1 is installed, for example, so that the longitudinal direction is parallel to the central axis of the static magnetic field magnet 101.

[0015] The bed control circuit 109 is a circuit that controls the bed 107, and drives the bed 107 in response to an instruction from an operator via an interface 125, thereby moving a top board 1071 in the longitudinal direction and the vertical direction.

[0016] The transmitting coil 115 is an RF coil disposed inside the gradient magnetic field coil 103. The transmitting coil 115 receives a supply of RF (Radio Frequency) pulses from the transmitting circuit 113 and generates a transmitting RF wave corresponding to a high frequency magnetic field. The transmitting coil 115 is, for example, a whole body coil. The whole body coil may be used as a transmitting / receiving coil. A cylindrical RF shield is installed between the whole body coil and the gradient magnetic field coil 103 to magnetically separate these coils.

[0017] The transmission circuit 113 supplies an RF pulse corresponding to the Larmor frequency or the like to the transmission coil 115 under the control of the sequence control circuit 121 .

[0018] The receiving coil 117 is an RF coil disposed inside the gradient magnetic field coil 103. The receiving coil 117 receives an MR signal emitted from the subject P by a high frequency magnetic field. The receiving coil 117 outputs the received MR signal to a receiving circuit 119. The receiving coil 117 is, for example, a coil array having one or more, typically a plurality of coil elements. The receiving coil 117 is, for example, a phased array coil.

[0019] The receiving circuit 119 generates a digital MR signal, which is digitized complex data, based on the MR signal output from the receiving coil 117 under the control of the sequence control circuit 121. Specifically, the receiving circuit 119 performs various signal processing on the MR signal output from the receiving coil 117, and then performs analog-to-digital (A / D) conversion on the data that has been subjected to various signal processing. The receiving circuit 119 samples the A / D converted data. As a result, the receiving circuit 119 generates a digital MR signal (hereinafter referred to as MR data). The receiving circuit 119 outputs the generated MR data to the sequence control circuit 121.

[0020] The sequence control circuit 121 controls the gradient magnetic field power supply 105, the transmission circuit 113, the reception circuit 119, etc. according to the examination protocol output from the processing circuit 131, and performs imaging of the subject P. The examination protocol has various pulse sequences (also called imaging sequences) according to the examination. The examination protocol defines the magnitude of the current supplied to the gradient magnetic field coil 103 by the gradient magnetic field power supply 105, the timing at which the gradient magnetic field power supply 105 supplies the current to the gradient magnetic field coil 103, the magnitude of the RF pulse supplied to the transmission coil 115 by the transmission circuit 113, the timing at which the RF pulse is supplied to the transmission coil 115 by the transmission circuit 113, the timing at which the MR signal is received by the reception coil 117, etc.

[0021] The bus 123 is a transmission path for transmitting data between the interface 125, the display 127, the storage device 129, and the processing circuit 131. Various biosignal measuring devices, external storage devices, various modalities, and the like may be appropriately connected to the bus 123 via a network or the like. For example, an electrocardiograph (not shown) is connected to the bus as a biosignal measuring device.

[0022] The interface 125 has a circuit for receiving various instructions and information input from an operator. The interface 125 has a circuit for an input device such as a pointing device such as a mouse or a keyboard. The circuits of the interface 125 are not limited to circuits for physical operation parts such as a mouse and a keyboard. For example, the interface 125 may have an electrical signal processing circuit for receiving an electrical signal corresponding to an input operation from an external input device provided separately from the MRI apparatus 1 and outputting the received electrical signal to various circuits.

[0023] The display 127 displays various magnetic resonance images (MR images) generated by the image generation function 1313, various information related to imaging and image processing, and the like under the control of the system control function 1311 in the processing circuit 131. The display 127 is, for example, a display device such as a CRT display, a liquid crystal display, an organic EL display, an LED display, a plasma display, or any other display or monitor known in the art.

[0024] The storage device 129 stores MR data filled in the k-space via the image generating function 1313, image data generated by the image generating function 1313, etc. The storage device 129 stores imaging conditions including various examination protocols and a plurality of imaging parameters defining the examination protocols, etc. The storage device 129 stores programs corresponding to various functions executed by the processing circuitry 131. The storage device 129 is, for example, a semiconductor memory element such as a random access memory (RAM) or a flash memory, a hard disk drive, a solid state drive, an optical disk, etc. The storage device 129 may also be a drive device that reads and writes various information to and from a portable storage medium such as a CD-ROM drive, a DVD drive, or a flash memory.

[0025] The magnet management unit 2 includes a temperature measurement circuit 20 . The temperature measuring circuit 20 measures the temperature of one or more superconducting coils forming the static magnetic field magnet 101 that generates a static magnetic field, using a temperature sensor.

[0026] The processing circuitry 131 has a processor, memories such as a ROM (Read-Only Memory) and a RAM, etc., which are not shown as hardware resources, and performs overall control of the MRI apparatus 1. The processing circuitry 131 includes a system control function 1311, an image generation function 1313, a calculation function 1315, an input restriction function 1317, a user interface function 1319, a presentation function 1321, an estimation function 1323, and a determination function 1325.

[0027] Various functions of the processing circuitry 131 are stored in the storage device 129 in the form of programs executable by a computer. The processing circuitry 131 is a processor that realizes the functions corresponding to the various functions by reading the programs corresponding to the various functions from the storage device 129 and executing them. In other words, the processing circuitry 131 in a state in which each program has been read out has the multiple functions and the like shown in the processing circuitry 131 in FIG.

[0028] 1, it has been described that these various functions are realized by a single processing circuit 131, but it is also possible to configure the processing circuit 131 by combining a plurality of independent processors, and to configure each processor to realize a function by executing a program. In other words, it is also possible that each of the above-mentioned functions is configured as a program and one processing circuit executes each program, or that a specific function is implemented in a dedicated independent program execution circuit.

[0029] In addition, the term "processor" used in the above description refers to circuits such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or an Application Specific Integrated Circuit (ASIC), a programmable logic device (e.g., a Simple Programmable Logic Device (SPLD), a Complex Programmable Logic Device (CPLD), and a Field Programmable Gate Array (FPGA)).

[0030] The processor realizes various functions by reading and executing programs stored in the storage device 129. Note that instead of storing the programs in the storage device 129, the programs may be directly built into the circuitry of the processor. In this case, the processor realizes functions by reading and executing the programs built into the circuitry. Note that the bed control circuitry 109, the transmission circuitry 113, the reception circuitry 119, the sequence control circuitry 121, and the like are also similarly constituted by electronic circuits such as the above-mentioned processor.

[0031] The processing circuitry 131 controls the MRI apparatus 1 by the system control function 1311. Specifically, the processing circuitry 131 reads out a system control program stored in the storage device 129, expands it on the memory, and controls each circuit of the MRI apparatus 1 according to the expanded system control program. For example, the processing circuitry 131 reads out an examination protocol from the storage device 129 based on the imaging conditions input by the operator via the interface 125 by the system control function 1311. The processing circuitry 131 may generate the examination protocol based on the imaging conditions. The processing circuitry 131 transmits the examination protocol to the sequence control circuitry 121 and controls imaging of the subject P.

[0032] The processing circuitry 131 applies an excitation pulse and applies a gradient magnetic field according to an excitation pulse sequence using a system control function 1311. After executing the excitation pulse sequence using the system control function 1311, the processing circuitry 131 collects MR signals from the subject P according to a data collection sequence, which is a pulse sequence for collecting various types of data, and generates MR data.

[0033] The processing circuitry 131 fills the MR data along the readout direction of the k-space according to the strength of the readout gradient magnetic field by the image generation function 1313. The processing circuitry 131 generates an MR image by performing a Fourier transform on the MR data filled in the k-space. For example, the processing circuitry 131 can generate an absolute value (magnitude) image from the complex MR data. The processing circuitry 131 can also generate a phase image using real part data and imaginary part data in the complex MR data. The processing circuitry 131 outputs the MR images such as the absolute value image and the phase image to the display 127 or the storage device 129.

[0034] The processing circuit 131 calculates, by the calculation function 1315, an allowable limit value for the heat quantity of the superconducting magnet based on one or more imaging parameters for determining the imaging conditions. The processing circuit 131 uses the input limiting function 1317 to limit the range of imaging parameters input by the operator based on the imaging limit conditions. The processing circuitry 131 receives, via a user interface function 1319, input of one or more imaging parameters for determining imaging conditions. The processing circuitry 131 uses the presentation function 1321 to present to the operator at least one of the marginal imaging condition and a converted value obtained by converting the marginal imaging condition into a value correlated with the risk. The processing circuit 131 uses the estimation function 1323 to estimate a feature amount related to the heat input to the static magnetic field magnet when imaging is performed under the imaging conditions. The processing circuit 131 uses the determination function 1325 to determine whether or not the feature amount satisfies the limit imaging condition.

[0035] Next, an imaging management process of the MRI apparatus 1 according to this embodiment will be described with reference to the flowchart of Fig. 2. It is assumed that the process shown in the flowchart of Fig. 2 is executed, for example, when determining imaging conditions for one imaging sequence.

[0036] In step S201, the processing circuitry 131 calculates the limit imaging condition of the imaging parameters that can be set for the imaging sequence using the calculation function 1315. A method for calculating the limit imaging condition will be described later with reference to Figs. In step S202, the processing circuitry 131 acquires imaging parameters related to imaging conditions operated by the operator on the user interface screen or directly input by the operator through the user interface function 1319. At this time, the processing circuitry 131 restricts the input range of imaging parameters from the operator on the user interface screen based on the limit imaging conditions through the input restriction function 1317. Specifically, for example, the input restriction function 1317 sets an upper limit value or a lower limit value of the imaging parameters, and restricts the input of values ​​larger than the upper limit value and values ​​smaller than the lower limit value.

[0037] In step S203, the processing circuit 131 estimates a feature amount related to heat amount, including the heat amount in the superconducting magnet, which is expected when imaging is performed under the imaging conditions acquired in step S202, by using the estimation function 1323. The feature amount is the heat amount and temperature change in the superconducting coil and the superconducting coil, and the heat input to the superconducting coil, when imaging the subject. Specifically, for example, a value related to the risk of quenching occurring after imaging may be estimated as the feature amount. In step S204, the processing circuit 131 determines whether or not the feature amount estimated in step S203 satisfies the limit imaging condition using the determination function 1325. If the feature amount satisfies the limit imaging condition, the process proceeds to step S207, and if the feature amount does not satisfy the limit imaging condition, the process proceeds to step S205.

[0038] In step S205, the processing circuit 131 judges whether or not to perform imaging by the judgment function 1325. For example, when there is an input from the operator regarding re-setting of imaging conditions, it is judged that there is a change in the conditions, and the process proceeds to step S206. On the other hand, when an instruction to cancel imaging is acquired from the operator, it is judged that imaging is not to be performed, and the process ends. In step S206, the processing circuitry 131 changes the imaging conditions by the user interface function 1319. For example, the processing circuitry 131 accepts an input from the operator regarding the change of the imaging conditions. Alternatively, the processing circuitry 131 may automatically set an alternative imaging condition. Then, the process returns to step S201 and the same process is repeated.

[0039] In step S207, the processing circuitry 131 confirms the imaging conditions acquired in step S202 because the imaging conditions acquired in step S202 satisfy the limit imaging conditions and imaging under those imaging conditions does not pose any risk, for example, no quenching occurs. In step S208, imaging is performed by the MRI apparatus 1 based on the imaging conditions determined in step S205.

[0040] In step S202, the processing circuit 131 may use the presentation function 1321 to present to the operator at least one of the limit imaging condition and a converted value obtained by converting the limit imaging condition into a value correlated with the risk. For example, the critical temperature at which the superconducting magnet quenches may be displayed as the limit imaging condition, and the remaining temperature from the current temperature of the superconducting magnet until the critical temperature is reached, or the percentage until the critical temperature is reached, may be displayed as the converted value. This allows the operator to refer to the imaging conditions when inputting them.

[0041] Alternatively, in step S202, the processing circuitry 131 may preset imaging conditions that satisfy the marginal imaging conditions. The operator may check the preset imaging parameters and input any corrections or additions. This can save the effort of inputting all imaging parameters related to the imaging conditions without having to input them from scratch.

[0042] The processes from step S203 to step S206 may be executed or omitted. That is, since the imaging conditions acquired in step S202 are within the range of the imaging conditions not exceeding the limit imaging conditions, imaging in step S208 may be executed after the process of step S202.

[0043] Next, details of the process of estimating the limit imaging condition in step S201 will be described with reference to the flowchart of FIG. In step S301, the processing circuit 131 calculates the amount of heat that can be generated by the calculation function 1315. Specifically, the amount of heat that can be generated (heat input) without quenching is calculated using information such as the current temperature of the static magnetic field magnet, the thermal equilibrium temperature of the structure wound with superconducting wire, the critical temperature at which the static magnetic field magnet quenches, the thermal characteristics of the static magnetic field magnet such as the heat capacity of the coil portion that generates the main magnetic field by the superconducting wire, the cooling capacity of the refrigerator, and the pressure of a refrigerant such as liquid helium when such a refrigerant is used.

[0044] In step S302, the processing circuitry 131 calculates the limit value of the imaging condition, that is, the limit imaging condition, based on the heat generation amount database by the calculation function 1315. The heat generation amount database is a database that stores the correspondence between the imaging condition and the heat generation amount, and is stored in, for example, the storage device 129 or an external storage device. Specifically, the processing circuitry 131 calculates, as the limit imaging condition, the limit value of the imaging condition related to heat generation, such as TR (Repetition time), slice thickness, and spatial resolution, based on the heat generation amount database, the heat generation amount calculated in step S301, and information including the type of imaging and the cross-sectional direction, by the calculation function 1315.

[0045] Next, a calculation example of the calorific value required for generating the calorific value database will be described with reference to FIG. Imaging with an MRI device involves various imaging conditions, such as the above-mentioned imaging sequence type, cross-sectional direction, TR, slice thickness, etc., and various imaging conditions are possible depending on the imaging purpose. However, since it takes a very long time to actually measure the amount of heat generated, it is not realistic to actually measure the amount of heat generated under all possible imaging conditions.

[0046] Therefore, in step S401 shown in FIG. 4, three gradient magnetic field waveforms for the Gx, Gy, and Gz directions are generated based on the imaging conditions such as the type of imaging sequence, the cross-sectional direction in imaging, and TR and ST. In step S402, time-series data of three gradient magnetic field waveforms when imaging is performed according to an imaging sequence is acquired.

[0047] In step S403, each time series data of the gradient magnetic field waveform is Fourier transformed to calculate frequency component data of each gradient magnetic field waveform. In step S404, the heat generation amount due to the gradient magnetic field waveform is estimated from the frequency component data of the gradient magnetic field waveform calculated in step S403 using a transfer function related to heat generation for the gradient magnetic field waveform of Gx, Gy, and Gz actually measured in advance. By storing the above results in a heat generation amount database, a heat generation amount database can be generated and the heat generation amount according to the imaging conditions can be calculated.

[0048] Next, an example of a transfer function used to calculate the amount of heat generated in step S404 will be described with reference to FIG. 5 is a graph showing the amount of heat generated versus the frequency components of the three gradient magnetic fields Gx, Gy, and Gz, where the vertical axis indicates the amount of heat generated, and the horizontal axis indicates the frequency components.

[0049] The transfer function is measured in the form of a transfer function for each of three gradient magnetic fields, which represents the relationship between the frequency components and the amount of heat that heats the superconducting wire and the support structure for the superconducting wire when a gradient magnetic field is applied in advance, for example, when the MRI apparatus 1 is installed or shipped. In order to calculate the transfer function, it is sufficient to calculate in advance the amount of heat generated for the imaging conditions assumed in actual imaging.

[0050] If the type of imaging sequence is the same, there is a simple correlation between the amount of heat generated and typical imaging conditions such as TR, number of slices, spatial resolution, etc. Therefore, by determining standard imaging conditions for each imaging sequence and measuring the amount of heat generated when imaging is performed under those imaging conditions, it is possible to determine the limit imaging conditions under which imaging can be performed without the risk of quenching by comparing with the standard imaging conditions.

[0051] Next, an example of a user interface screen that is also used by the user interface function 1319 will be described with reference to FIGS.

[0052] FIG. 6 shows a user interface screen including an MR image 61 captured in accordance with an imaging protocol, a table 62 indicating the type of imaging sequence and the imaging order, and a setting window 63 for setting imaging parameters. The state of the screen in FIG. 6 is such that imaging of the first imaging sequence "T1WI" in the table 62 has ended and imaging parameters of imaging conditions of the second imaging sequence "T2WI" are being set.

[0053] Next, a first display example of a user interface related to imaging parameters is shown in Fig. 7. Fig. 7 is an enlarged view of the setting window 63. Here, it is assumed that the operator inputs a value for the imaging parameter "TR". For example, when the TR frame is clicked, a slide bar 71 and a cursor 72 indicating the current value are displayed as a user interface in another window.

[0054] When other imaging conditions such as the number of slices are constant, as the TR becomes longer, the period during which the gradient magnetic field is not output becomes longer, and the amount of heat generated per unit time [W] decreases. In the direction in which the TR becomes shorter, a lower limit is set so that the cursor 72 cannot be slid to a value that does not satisfy the limit imaging condition of the heat input surface, and the lower limit value is displayed so that the operator can understand the lower limit. In the example of Figure 7, if the limit imaging condition of the heat input surface is not taken into consideration, the cursor 72 can be moved up to "10 ms", but it is displayed as grayed out (shaded area in Figure 7) so that the cursor 72 cannot be moved to a position below the lower limit of "40 ms", which is the limit imaging condition of the heat input surface.

[0055] Next, a second display example of a user interface relating to imaging parameters is shown in FIG. 8 is also an enlarged view of the setting window 63. Here, it is assumed that the operator inputs a value for the imaging parameter "resolution." For example, when the operator clicks on the "resolution" box, a list window 81 is displayed as a user interface.

[0056] Since the smaller the resolution value, i.e., the higher the resolution, the greater the amount of heat generated by the superconducting magnet, a lower limit is set so that a value with a lower resolution that does not satisfy the limiting imaging condition, in other words, a value that increases the amount of heat input, cannot be selected (input), and is displayed so that the operator can understand the lower limit. In the example of Figure 8, if the limiting imaging condition is set to "2mm," then if the limiting imaging condition is not taken into consideration, it is possible to select up to "1mm," but values ​​below the lower limit of "2mm," which is the limiting imaging condition, such as "1mm" and "0.5mm," are displayed as grayed out (shaded area in Figure 8) so that they cannot be selected.

[0057] When the processing circuit 131 receives a change in the imaging parameters from the operator on the user interface screen, the processing circuit 131 may update the input range of other imaging parameters related to the imaging conditions by the input limiting function 1317. For example, in the example of Fig. 7 and Fig. 8, when the resolution is changed from "3 mm" to "10 mm" based on the limit imaging conditions, it is considered that the limit of the heat input to the superconducting magnet is slightly relaxed, so that the TR of the imaging parameters may be updated to be changeable up to "8000 ms".

[0058] According to the present embodiment described above, before the imaging conditions are finalized, the limit imaging conditions are calculated based on one or more imaging parameters based on the heat generation database, and the range of the imaging parameters input by the operator is restricted based on the limit imaging conditions. As a result, the imaging conditions input are restricted to the range in which imaging is possible, and imaging can be performed under the input imaging conditions. Therefore, there is no need to reset the imaging conditions or redo imaging at the imaging execution stage. As a result, efficient examination can be supported.

[0059] In addition, each function according to the embodiment can be realized by installing a program for executing the corresponding process in a computer such as a workstation and expanding the program in memory. In this case, the program for causing the computer to execute the corresponding method can be stored in a storage medium such as a magnetic disk (such as a hard disk), an optical disk (such as a CD-ROM, DVD, Blu-ray (registered trademark) disk), or a semiconductor memory and distributed.

[0060] Although some embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations of embodiments can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0061] 1 MRI machine 2 Magnet Management Unit 20 Temperature measurement circuit 21 Sensor control unit 22 Calculation section 61 MR Imaging 62 Table 63 Settings Window 71 Slide bar 72 Cursor 81 List Window 101 Static magnetic field magnet 103 Gradient magnetic field coil 105 Gradient magnetic field power supply 107 Bed 109 Bed Control Circuit 111 Boa 113 Transmitting circuit 115 Transmitting Coil 117 Receiving coil 119 Receiving circuit 121 Sequence control circuit 123 Bus 125 Interface 127 Display 129 Storage device 131 Processing circuit 1311 System Control Functions 1313 Image generation function 1315 Calculation Function 1317 Input restriction function 1319 User Interface Functions 1321 Presentation function 1323 Estimation Function 1325 Judgment Function

Claims

1. A calculation unit that calculates a limit imaging condition based on a heat amount that is an allowable limit for heat input to a superconducting magnet and does not cause quenching, based on one or more imaging parameters for determining an imaging condition; and an input limiting unit that limits an input range of imaging parameters from an operator based on the limit imaging condition; an interface unit that displays the remaining temperature from the current temperature of the superconducting magnet to the critical temperature, or the percentage to the critical temperature; A magnetic resonance imaging apparatus comprising:

2. 2. The magnetic resonance imaging apparatus according to claim 1, further comprising a presentation unit that presents to the operator at least one of the limit imaging condition and a converted value obtained by converting the limit imaging condition into a value correlated with a risk.

3. 3. The magnetic resonance imaging apparatus according to claim 1, wherein the input restriction unit sets an upper limit value or a lower limit value of the one or more imaging parameters based on the limit imaging condition, and restricts input of a value greater than the upper limit value or a value less than the lower limit value.

4. 4. The magnetic resonance imaging apparatus according to claim 1, further comprising a user interface unit that accepts input of one or more imaging parameters for determining imaging conditions from an operator.

5. The magnetic resonance imaging apparatus according to claim 4 , wherein the input restriction unit changes the restricted input ranges of other imaging parameters related to the imaging conditions when the user interface unit accepts a change in the imaging parameters from the operator.

6. the user interface unit displays a slide bar that allows adjustment of a value of a target imaging parameter; the input limiting unit sets the slide bar so that it cannot be slid to a value that does not satisfy the limit imaging condition in a direction in which the heat input amount related to the superconducting magnet increases.

6. A magnetic resonance imaging apparatus according to claim 4 or 5.

7. 2. The magnetic resonance imaging apparatus according to claim 1, wherein the calculation unit calculates the limit imaging condition based on the one or more imaging parameters, a database indicating a correspondence relationship between imaging conditions and heat generation amounts, and information including a current temperature of a static magnetic field magnet and a cooling capacity of a refrigerator.

8. Calculating a limit imaging condition based on a heat amount that is a permissible limit for heat input to the superconducting magnet and does not cause quenching, based on one or more imaging parameters for determining the imaging condition; limiting an input range of imaging parameters from an operator based on the limit imaging condition; Displaying the remaining temperature from the current temperature of the superconducting magnet to the critical temperature, or the percentage to reach said critical temperature; Imaging management method.

Images