JP2023067578A - Magnetic resonance imaging apparatus and program - Google Patents

Abstract

To provide a magnetic resonance imaging apparatus and a program capable of detecting, an abnormality in gradient magnetic field coils, without providing a temperature sensor on the gradient magnetic field coil.SOLUTION: A measuring part measures a first temperature representing a temperature of coolant flowing from a cooling device into gradient magnetic field coils and a second temperature representing a temperature of the coolant flowing into the cooling device from the gradient magnetic field coils. The prediction part predicts, as a predicted value, an amount of heat generated by the gradient magnetic field coils when the gradient magnetic field coils are operated on the basis of operating conditions related to operation of the gradient magnetic field coils. The calculation part calculates the amount of heat generated by the gradient magnetic field coils as a measured value on the basis of a temperature difference between the first temperature and the second temperature measured when the gradient magnetic field coils are operated under the operating conditions related to the operation of the gradient magnetic field coils. A determination part determines whether an abnormality has occurred in the gradient magnetic field coils on the basis of a difference value between the predicted value and the actual measurement value.SELECTED DRAWING: Figure 1

Description

An embodiment of the present invention relates to a magnetic resonance imaging apparatus and program.

A magnetic resonance imaging apparatus (hereinafter referred to as "MRI (Magnetic Resonance Imaging) apparatus" as appropriate) generates nuclear magnetic resonance using three types of magnetic fields: a static magnetic field, a gradient magnetic field, and a high-frequency magnetic field, and reconstructs resonance signals. An image of the subject is obtained by processing.

Among them, the gradient magnetic field is generated by a gradient magnetic field coil and a gradient magnetic field amplifier. At this time, it is known that a large current flows through the gradient magnetic field coil, causing heat to be generated. If the calorific value of the gradient magnetic field coil becomes too high, the gradient magnetic field coil may fail. Conventionally, in order to prevent failure, a temperature sensor is provided in the gradient magnetic field coil to monitor the temperature of the gradient magnetic field coil.

The temperature sensor described above is provided, for example, inside or around the gradient magnetic field coil. However, since the internal structure of the gradient magnetic field coil is complicated, in the configuration in which the temperature sensor is provided inside the gradient magnetic field coil, the temperature sensor cannot be easily replaced when the cable of the temperature sensor is broken. , the gradient coil itself may become unusable. In addition, in the configuration in which the temperature sensor is provided around the gradient magnetic field coil, there is a possibility that it will interfere with the inner gantry components.

JP 2013-228614 A

A problem to be solved by the present invention is to provide a magnetic resonance imaging apparatus and a program capable of detecting abnormal heat generation of a gradient magnetic field coil without providing a temperature sensor in the gradient magnetic field coil.

A magnetic resonance imaging apparatus according to an embodiment includes a gradient magnetic field coil, a cooling device, a measurement section, a prediction section, a calculation section, and a determination section. A gradient magnetic field coil applies a gradient magnetic field. The cooling device cools the gradient magnetic field coil by circulating a coolant. The measuring unit measures a first temperature indicating the temperature of the coolant flowing from the cooling device into the gradient magnetic field coil and a second temperature indicating the temperature of the cooling device flowing from the gradient magnetic field coil to the cooling device. The prediction unit predicts, as a predicted value, the amount of heat generated by the gradient magnetic field coils when the gradient magnetic field coils are operated under the operating conditions based on the operating conditions related to the operation of the gradient magnetic field coils. The calculation unit calculates the amount of heat generated by the gradient magnetic field coil as a measured value based on the temperature difference between the first temperature and the second temperature measured when the gradient magnetic field coil is operated under the operating conditions related to the operation of the gradient magnetic field coil. Calculate as The determination unit determines whether or not an abnormality has occurred in the gradient magnetic field coil based on the difference value between the predicted value and the actual measurement value.

FIG. 1 is a functional block diagram showing the configuration of the MRI apparatus according to the first embodiment. FIG. 2 is a block diagram showing the configuration of the cooling system according to the first embodiment. FIG. 3 is a block diagram showing the configuration of the gradient coil cooling device according to the first embodiment. FIG. 4 is a flowchart illustrating an example of processing executed by the MRI apparatus according to the first embodiment; FIG. 5 is a functional block diagram showing the configuration of the MRI apparatus according to the second embodiment. FIG. 6 is a flow chart showing an example of processing executed by the MRI apparatus according to the second embodiment. FIG. 7 is a functional block diagram showing the configuration of an MRI apparatus according to a modification. FIG. 8 is a flowchart showing an example of processing executed by the MRI apparatus according to the modification.

Hereinafter, a magnetic resonance imaging apparatus (hereinafter referred to as an "MRI apparatus" as appropriate) and a program according to an embodiment will be described with reference to the drawings. In addition, embodiment is not restricted to the following embodiments.

(First embodiment)
FIG. 1 is a functional block diagram showing the configuration of the MRI apparatus 100 according to the first embodiment. As shown in FIG. 1, the MRI apparatus 100 includes a static magnetic field magnet 1, a gradient magnetic field coil 2, a gradient magnetic field power supply 3, a transmission coil 4, a transmission circuit 5, a reception coil 6, a reception circuit 7, It comprises a bed 8 , an input circuit 9 , a display 10 , a memory circuit 11 , processing circuits 12 to 15 and a cooling system 200 . A main cooling device 300 is connected to the cooling system 200 .

Note that the MRI apparatus 100 does not include the subject S (eg, human body) shown in FIG. Also, the configuration shown in FIG. 1 is merely an example.

The static magnetic field magnet 1 is formed in a hollow, substantially cylindrical shape (including one having an elliptical cross section perpendicular to the central axis of the cylinder), and generates a uniform static magnetic field in the imaging space formed on the inner peripheral side. Let For example, the static magnetic field magnet 1 is realized by a permanent magnet, a superconducting magnet, or the like.

The gradient magnetic field coil 2 is formed in a hollow, substantially cylindrical shape (including one having an elliptical cross section perpendicular to the central axis of the cylinder), and is arranged on the inner peripheral side of the static magnetic field magnet 1 . The gradient magnetic field coil 2 has three coils that generate gradient magnetic fields along the mutually orthogonal x-, y-, and z-axes.

Here, the x-axis, y-axis, and z-axis constitute an apparatus coordinate system unique to the MRI apparatus 100 . For example, the direction of the x-axis is set vertically and the direction of the y-axis is set horizontally. Also, the direction of the z-axis is set to be the same as the direction of the magnetic flux of the static magnetic field generated by the static magnetic field magnet 1 .

Further, the gradient magnetic field coil 2 has a cooling pipe inside. The cooling pipe is spirally embedded inside the gradient magnetic field coil 2 . The cooling pipes circulate cooling water supplied from the cooling system 200 . As a result, the heat generated in the gradient magnetic field coil 2 is absorbed by the cooling water, and the gradient magnetic field coil 2 can be cooled.

The gradient magnetic field power supply 3 individually supplies currents to the three coils of the gradient magnetic field coil 2 to generate gradient magnetic fields along the x-axis, the y-axis, and the z-axis in the imaging space. By appropriately generating gradient magnetic fields along the x-, y-, and z-axes, it is possible to generate gradient magnetic fields along the readout direction, the phase-encode direction, and the slice direction, which are orthogonal to each other.

Here, axes along each of the readout direction, phase encoding direction, and slice direction constitute a logical coordinate system for defining a slice region or volume region to be imaged. Hereinafter, the gradient magnetic field along the readout direction is called the readout gradient magnetic field, the gradient magnetic field along the phase encode direction is called the phase encode gradient magnetic field, and the gradient magnetic field along the slice direction is called the slice gradient magnetic field. .

Each gradient magnetic field is superimposed on the static magnetic field generated by the static magnetic field magnet 1 and used to give spatial position information to magnetic resonance (MR) signals. Specifically, the readout gradient magnetic field changes the frequency of the MR signal according to the position in the readout direction, thereby imparting positional information along the readout direction to the MR signal.

Also, the phase-encoding gradient magnetic field changes the phase of the MR signal along the phase-encoding direction, thereby imparting positional information in the phase-encoding direction to the MR signal.

When the imaging region is a slice region, the slice gradient magnetic field is used to determine the direction, thickness, and number of slice regions. By changing the phase of the MR signal using the MR signal, positional information along the slice direction is added to the MR signal.

The transmission coil 4 is formed in a hollow, substantially cylindrical shape (including one having an elliptical cross section perpendicular to the central axis of the cylinder), and is arranged inside the gradient magnetic field coil 2 . The transmission coil 4 applies an RF (Radio Frequency) pulse output from the transmission circuit 5 to the imaging space.

The transmission circuit 5 outputs RF pulses corresponding to the Larmor frequency to the transmission coil 4 . For example, the transmission circuit 5 has an oscillation circuit, a phase selection circuit, a frequency conversion circuit, an amplitude modulation circuit, and an RF amplification circuit. An oscillating circuit generates RF pulses at a resonant frequency characteristic of nuclei of interest placed in a static magnetic field. The phase selection circuit selects the phase of the RF pulse output from the oscillation circuit.

A frequency conversion circuit converts the frequency of the RF pulse output from the phase selection circuit. The amplitude modulation circuit modulates the amplitude of the RF pulse output from the frequency conversion circuit according to, for example, a sinc function. The RF amplifier circuit amplifies the RF pulse output from the amplitude modulation circuit and outputs the amplified RF pulse to the transmission coil 4 .

The receiving coil 6 is arranged inside the gradient magnetic field coil 2 and receives MR signals emitted from the subject S under the influence of RF pulses. Upon receiving the MR signal, the receiving coil 6 outputs the received MR signal to the receiving circuit 7 .

The receiving circuit 7 generates MR signal data based on the MR signal output from the receiving coil 6 and outputs the generated MR signal data to the processing circuit 13 . For example, the receiving circuit 7 has a selection circuit, a preamplifier circuit, a phase detection circuit, and an analog-to-digital conversion circuit. The selection circuit selectively inputs the MR signal output from the receiving coil 6 .

The pre-amplifier circuit amplifies the MR signal output from the selection circuit. The phase detection circuit detects the phase of the MR signal output from the preamplifier. The analog-to-digital conversion circuit converts the analog signal output from the phase detector into a digital signal to generate MR signal data, and outputs the generated MR signal data to the processing circuit 13 .

An example in which the transmission coil 4 applies an RF pulse and the reception coil 6 receives an MR signal will be described here, but the configuration of the transmission coil and the reception coil is not limited to this. For example, the transmission coil 4 may further have a reception function for receiving MR signals. Also, the receiving coil 6 may further have a transmitting function of applying an RF magnetic field.

If the transmission coil 4 has a reception function, the reception circuit 7 also generates MR signal data from the MR signals received by the transmission coil 4 . Moreover, when the receiving coil 6 has a transmitting function, the transmitting circuit 5 also outputs the RF pulse to the receiving coil 6 .

The bed 8 has a top plate 8a on which the subject S is placed. insert For example, the bed 8 is installed so that its longitudinal direction is parallel to the central axis of the static magnetic field magnet 1 .

The input circuit 9 receives input operations of various instructions and various information from the operator. For example, the input circuit 9 is implemented by a trackball, switch button, mouse, keyboard, touch panel, or the like. The input circuit 9 is connected to the processing circuit 15 , converts an input operation received from an operator into an electric signal, and outputs the electric signal to the processing circuit 15 .

The display 10 displays various information and various images. For example, the display 10 is realized by a liquid crystal monitor, a CRT (Cathode Ray Tube) monitor, a touch panel, or the like. The display 10 is connected to the processing circuit 15 and converts various information and image data sent from the processing circuit 15 into electrical signals for display and outputs the electrical signals.

The storage circuit 11 stores various data. For example, the storage circuit 11 stores MR signal data and image data for each subject S. For example, the storage circuit 11 is realized by a RAM (Random Access Memory), a semiconductor memory device such as a flash memory, a hard disk, an optical disk, or the like.

The processing circuit 12 has a bed control function 12a. For example, processing circuitry 12 is implemented by a processor.

The bed control function 12 a is connected to the bed 8 and controls the operation of the bed 8 by outputting electrical signals for control to the bed 8 . For example, the bed control function 12a receives an instruction from the operator via the input circuit 9 to move the tabletop 8a in the longitudinal direction, the vertical direction, or the horizontal direction, and moves the tabletop 8a according to the received instruction. The drive mechanism of the top plate 8a of the bed 8 is operated.

The processing circuit 13 has a sequence control function 13a. For example, the processing circuitry 13 is implemented by a processor. The sequence control function 13a executes various protocols. Note that the sequence control function 13a is an example of a first control unit. Specifically, the sequence control function 13a drives the gradient magnetic field power supply 3, the transmission circuit 5, and the reception circuit 7 based on the sequence execution data output from the processing circuit 15, thereby executing various protocols.

Here, the sequence execution data is information defining a protocol indicating procedures for acquiring MR signal data. Specifically, the sequence execution data includes the timing and strength of the current supplied by the gradient magnetic field power supply 3 to the gradient magnetic field coil 2, the strength of the RF pulse current supplied to the transmission coil 4 by the transmission circuit 5, and the This information defines the supply timing, the detection timing for detecting the MR signal by the receiving circuit 7, and the like.

The sequence control function 13 a also receives MR signal data from the receiving circuit 7 as a result of executing various pulse sequences, and stores the received MR signal data in the storage circuit 11 .

The set of MR signal data received by the sequence control function 13a is arranged two-dimensionally or three-dimensionally according to the position information given by the readout gradient magnetic field, the phase-encoding gradient magnetic field, and the slice gradient magnetic field. Thus, it is stored in the storage circuit 11 as data forming the k-space.

The sequence control function 13 a also sends a temperature control signal including the target temperature of the cooling water to the cooling system 200 . Since the amount of heat generated by the gradient magnetic field coil 2 differs depending on the protocol to be executed, the target temperature of the cooling water is preferably changed according to the protocol. Specifically, it is preferable to set the target temperature of the cooling water to be lower for a protocol that generates a larger amount of heat. The target temperature of cooling water can be determined, for example, by a target temperature determination table that associates the protocol with the target temperature of cooling water.

The cooling system 200 controls the temperature of the gradient coil 2 based on the temperature control signal. The cooling system 200 will be described below.

The cooling system 200 flows temperature-controlled water through the cooling pipe of the gradient coil 2 . For example, the cooling system 200 cools the gradient magnetic field coil 2 by flowing low-temperature water through the cooling pipe of the gradient magnetic field coil 2 . Further, for example, the gradient magnetic field coil 2 is heated by flowing warm water through the cooling pipe of the gradient magnetic field coil 2 .

The cooling system 200 adjusts the temperature of the water flowing back through the cooling pipe of the gradient magnetic field coil 2 and flows it through the cooling pipe again. Thus, the cooling system 200 controls the temperature of the gradient coil 2 by circulating water between the gradient coil 2 and the cooling system 200 .

Next, the configuration of the cooling system 200 according to this embodiment will be described. FIG. 2 is a block diagram showing the configuration of the cooling system 200 according to the embodiment. As shown in FIG. 2, the cooling system 200 includes a gradient coil cooling device 220, a valve 240a, a valve 240b, a temperature sensor 260a, and a temperature sensor 260b.

The valves 240 a and 240 b control the flow of cooling water supplied to the gradient coil 2 from the main cooling device 300 and the gradient coil cooling device 220 under the control of the gradient coil cooling device 220 .

These valves 240 a and 240 b allow either cooling water supplied by the main cooling device 300 or cooling water supplied by the gradient coil cooling device 220 to flow through the gradient coil 2 .

In addition, the valves 240a and 240b can mix cooling water supplied from each cooling device of the main cooling device 300 and the gradient coil cooling device 220 and circulate it to the gradient magnetic field coil 2. It is also possible to adjust the ratio appropriately.

A temperature sensor 260a and a temperature sensor 260b measure the temperature of the cooling water. The temperature sensor 260 a measures a first temperature, which is the temperature of cooling water supplied to the gradient coil 2 from each of the main cooling device 300 and the gradient coil cooling device 220 . The temperature sensor 260b measures the second temperature, which is the temperature of the cooling water returning from the gradient coil 2 to each of the main cooling device 300 and the gradient coil cooling device 220 .

The temperature sensor 260a and the temperature sensor 260b transmit the measurement results to the cooling device 220 for gradient magnetic field coils. The processing circuit 15 , which will be described later, obtains the first temperature and the second temperature from the gradient coil cooling device 220 and calculates the measured value of the heat generation amount of the gradient coil 2 .

The main cooling device 300 circulates cooling water through the cooling pipe of the gradient coil 2 . Specifically, the main cooling device 300 causes cooling water at a constant temperature to flow into the gradient magnetic field coil 2 through a flow path passing through the valve 240a.

In addition, the main cooling device 300 takes in the cooling water flowing out from the gradient magnetic field coil 2 through a flow path passing through the valve 240b. Although not shown in FIG. 2, the main cooling device 300 circulates cooling water to various units other than the gradient coil 2 as well.

The gradient magnetic field coil cooling device 220 circulates cooling water to the gradient magnetic field coil 2 via a cooling water flow path provided between the main cooling device 300 and the gradient magnetic field coil 2 . The gradient coil cooling device 220 is communicably connected to the processing circuit 13, the processing circuit 15, the valve 240a, the valve 240b, the temperature sensor 260a, and the temperature sensor 260b.

Specifically, the gradient magnetic field coil cooling device 220 has a higher temperature than the cooling water supplied by the main cooling device 300 to the flow path leading from the main cooling device 300 to the gradient magnetic field coil 2 via the valve 240a. Supply cooling water. In addition, the gradient coil cooling device 220 takes in part of the cooling water flowing out of the gradient coil 2 via the valve 240b.

In the present embodiment, the gradient coil cooling device 220 controls the state of the cooling water flowing from the main cooling device 300 to the gradient coil 2 so that the temperature of the cooling water flowing into the gradient coil 2 is change. Thereby, in this embodiment, the temperature change of the gradient magnetic field coil 2 is suppressed according to the magnitude of the heat generated during scanning. The gradient coil cooling device 220 will be described in detail below.

First, the configuration of the gradient coil cooling device 220 according to the present embodiment will be described. FIG. 3 is a block diagram showing the configuration of the gradient coil cooling device 220 according to the embodiment. As shown in FIG. 3 , the gradient coil cooling device 220 has a heater 221 and a cooling control section 222 .

The heater 221 heats the cooling water supplied by the gradient coil cooling device 220 . For example, the heater 221 appropriately adjusts the temperature of the cooling water supplied from the gradient coil cooling device 220 by changing the heating temperature for heating the cooling water under the control of the cooling control unit 222 .

The cooling control unit 222 controls the cooling system 200 based on the temperature control signal so that the temperature of the cooling water supplied by the gradient coil cooling device 220 reaches the target temperature of the cooling water.

Specifically, the cooling control unit 222 controls the valves 240a, 240b, and the heater 221, and the temperature of the cooling water flowing into the gradient magnetic field coil 2 is included in the temperature control signal received from the sequence control function 13a. Adjust to target temperature.

The cooling control unit 222 sends a valve control signal to the valves 240a and 240b so that the cooling water supplied from the main cooling device 300 and the gradient coil cooling device 220 is mixed and flowed into the gradient coil 2. to control.

The cooling control unit 222 does not adjust the temperature of the cooling water until the sequence control function 13a finishes executing the protocol after starting to supply the cooling water adjusted to the target temperature. This is because the amount of heat generated by the gradient magnetic field coil 2 is calculated based on the temperature difference between the temperature of the water supplied to the gradient magnetic field coil 2 and the temperature of the water returned from the gradient magnetic field coil 2 .

Returning to FIG. 1, the description is continued. The processing circuit 14 has an image generation function 14a. For example, processing circuitry 14 is implemented by a processor. The image generation function 14 a generates an image based on the MR signal data stored in the memory circuit 11 .

Specifically, the image generation function 14a reads the MR signal data stored in the storage circuit 11 by the sequence control function 13a, and performs post-processing, that is, reconstruction processing such as Fourier transform on the read MR signal data to generate an image. to generate Further, the image generation function 14 a stores the image data of the generated image in the storage circuit 11 .

The processing circuit 15 performs overall control of the MRI apparatus 100 by controlling each component of the MRI apparatus 100 . For example, the processing circuitry 15 is implemented by a processor. For example, the processing circuit 15 has a setting function 15a, a prediction function 15b, an acquisition function 15c, an arithmetic function 15d, a determination function 15e, a stop control function 15f, and a display control function 15g.

Note that the prediction function 15b is an example of a prediction unit. Also, the computing function 15d is an example of a computing section. Also, the determination function 15e is an example of a determination unit. The stop control function 15f is an example of a second control section. Also, the display control function 15g is an example of a notification unit.

The setting function 15a controls the sequence control function 13a to execute various protocols. Specifically, the setting function 15a receives, from the operator, a protocol group to be executed in the examination of the subject S and parameters of each protocol included in the protocol group as imaging conditions of the protocol. Further, the setting function 15 a sets the imaging conditions of the protocol by storing the received imaging conditions of the protocol in the storage circuit 11 .

Here, the imaging conditions are conditions set for imaging. For example, the imaging conditions include imaging time, TR (Repetition Time), TE (Echo Time), FA (Flip Angle), number of slices (NS (Number Of Slice)), FOV (Field Of View), slice thickness (ST (Slice Thickness)) and other operating conditions such as the frequency and duty cycle of the pulse sequence relating to the operation of the gradient magnetic field coil 2 are included.

That is, when the protocol is executed by the sequence control function 13a, the gradient magnetic field coil 2 operates under the operating conditions set in the protocol. Hereinafter, the operating conditions of the gradient magnetic field coil 2 are also referred to as imaging conditions including the operating conditions, or as protocols.

Further, a test in this embodiment is, for example, a set of one or more protocols. One examination is performed on one subject S. FIG. In one protocol, for example, data acquisition such as imaging is performed according to one pulse sequence.

For example, the setting function 15a cooperates with the display control function 15g to cause the display 10 to display an imaging condition setting screen for receiving the imaging conditions of the protocol, and the input of the imaging conditions of the protocol by the operator is received by the input circuit 9. accepted through

The setting function 15a stores the imaging conditions of the received protocol in the storage circuit 11, and generates sequence execution data according to the imaging conditions of the received protocol. The setting function 15 a outputs the generated sequence execution data to the processing circuit 13 .

For example, the setting function 15a sets a protocol group selected by the operator from among a plurality of protocol groups preset in the storage circuit 11 as a protocol group scheduled to be executed in the examination of the subject S. The setting function 15a also sets various parameters such as the imaging time set by the operator as imaging conditions.

Each protocol in the set protocol group is sequentially retrieved in a preset order by the setting function 15a, and various data such as imaging are collected according to the retrieved protocol.

Examples of protocols include "locator", "shimming", "EPI", "DWI", "TOF", "T2WI", "T1WI", "3D", and "T2*WI". “locator” is a protocol for capturing positioning images. Also, "shimming" is a protocol for adjusting the homogeneity of a magnetic field (eg, a static magnetic field). Note that the protocol "shimming" also measures the center frequency of the RF pulse.

"EPI" is a protocol for imaging by echo planar imaging (EPI) scanning. "DWI" is a protocol for imaging a diffusion weighted image. Also, "TOF" is a protocol for imaging by the TOF (Time of Flight) method. "T2WI" is a protocol for capturing a transverse relaxation weighted image (T2 weighted image).

"T1WI" is a protocol for capturing a longitudinal relaxation weighted image (T1 weighted image). "3D" is a protocol for capturing three-dimensional images. "T2*WI" is a protocol for capturing a T2* weighted image (T2 star weighted image).

The prediction function 15b predicts, as a predicted value, the amount of heat generated by the gradient magnetic field coil 2 when the gradient magnetic field coil 2 is operated under the operating conditions based on the operating conditions for the operation of the gradient magnetic field coil 2 .

Specifically, the prediction function 15b predicts the amount of heat generated in the gradient magnetic field coil 2 during execution of the protocol based on the imaging conditions of the protocol. For example, the prediction function 15b predicts the amount of heat generated by the gradient magnetic field coil 2 when the protocol set by the setting function 15a is executed based on the frequency (waveform) of the pulse sequence. Further, when a plurality of protocols are set by the setting function 15a, the prediction function 15b predicts the amount of heat generated for each protocol. Hereinafter, the amount of heat generated predicted by the arithmetic function 15d is also referred to as a "predicted value".

Note that the method for predicting the amount of heat generated is not particularly limited, and a known technique can be used. For example, the prediction function 15b may specify a predicted calorific value using a setting table that associates a protocol with a calorific value actually measured when the protocol is executed. Further, the prediction function 15b derives a predicted value of the calorific value from the protocol using a relational expression or model (a temperature change prediction model to be described later) capable of deriving the calorific value actually measured when the protocol is executed. may

For example, the prediction function 15b may prepare a "temperature change prediction model" in advance and use this "temperature change prediction model" to predict the temperature change of the gradient coil 2 before executing the protocol.

The “temperature change prediction model” is derived, for example, during the development stage of the MRI apparatus 100 . In this case, the gradient magnetic field coil 2 of the MRI apparatus 100 in the development stage is provided with a temperature sensor for measuring the temperature of the gradient magnetic field coil 2 . The temperature sensor is provided, for example, at a representative point of the gradient magnetic field coil 2, such as a portion where the temperature is likely to rise or a portion where heat is likely to accumulate.

The MRI apparatus 100 in the development stage has data related to the temperature of the cooling water, the duty cycle of the pulse sequence to be executed, etc., and data such as the temperature data of the gradient magnetic field coil 2 when no abnormality is found in the gradient magnetic field coil 2. to collect. The "temperature change prediction model" expresses the relationship between the temperature of the cooling water, the duty cycle of the pulse sequence to be executed, etc., and the temperature change of the gradient magnetic field coil 2, for example, based on the collected data. .

In other words, the "temperature change prediction model" represents how the temperature of the gradient magnetic field coil 2 changes when various pulse sequences are executed in a state where no abnormality is found in the gradient magnetic field coil 2 (normal time). can be said to be a model.

The "temperature change prediction model" may be generated by machine learning, deep learning, or the like. In this case, the "temperature change prediction model" functions to output information representing the temperature change of the gradient magnetic field coil 2 according to the input of data such as the temperature of the cooling water and the duty cycle of the pulse sequence to be executed. It is a trained model attached.

In this case, the prediction function 15b, before executing the protocol, based on the "temperature change prediction model" and data such as the cooling water temperature before the protocol execution and the duty cycle of the pulse sequence to be executed, the gradient magnetic field coil 2 predict the temperature change of

The determination function 15e calculates a predicted value of the amount of heat generated by the gradient magnetic field coil 2 calculated based on the temperature rise of the gradient magnetic field coil 2 predicted by the prediction function 15b, a first temperature at the start of protocol execution, and a first temperature at the end of protocol execution. It is determined whether or not there is an abnormality in the gradient coil 2 based on the measured value of the amount of heat generated by the gradient coil 2 calculated based on the second temperature.

By making a prediction using the "temperature change prediction model", the MRI apparatus 100 normally operates based on data on the temperature of the gradient magnetic field coil 2 collected together with the temperature of the cooling water and the duty cycle of the pulse sequence to be executed. , the temperature rise of the gradient coil 2 can be predicted. Therefore, an abnormality in the gradient magnetic field coil can be detected with higher accuracy.

The acquisition function 15c acquires the first temperature and the second temperature measured by the temperature sensors 260a and 260b from the cooling device 220 for gradient magnetic field coils. Specifically, the acquisition function 15c acquires the first temperature and the second temperature measured when the sequence control function 13a executes the protocol.

For example, the acquisition function 15c acquires the first temperature at the time when execution of the protocol is started. Also, the acquisition function 15c acquires the second temperature at the time when the execution of the protocol is finished. Moreover, when a plurality of protocols are executed, the acquisition function 15c acquires the first temperature and the second temperature for each protocol.

In this embodiment, the acquisition function 15c acquires the first temperature and the second temperature via the gradient coil cooling device 220, but is not limited to this configuration. For example, by communicably connecting the temperature sensors 260a and 260b to the processing circuit 15, the acquisition function 15c may directly acquire the first temperature and the second temperature from the temperature sensors 260a and 260b. good.

The calculation function 15d calculates the amount of heat generated by the gradient magnetic field coil 2 as a measured value based on the temperature difference between the first temperature and the second temperature measured when the sequence control function 13a executes the protocol.

For example, the arithmetic function 15d determines the temperature difference between the first temperature acquired at the start of the protocol execution and the second temperature acquired at the end of the protocol execution, based on the Calculate the calorific value. For example, the arithmetic function 15d calculates the amount of heat required to change the temperature of the cooling water from the first temperature to the second temperature as the amount of heat generated by the gradient magnetic field coil 2. FIG. Hereinafter, the calorific value calculated by the arithmetic function 15d is also referred to as "actual measurement value".

Various methods can be adopted for the method of calculating the actual measurement value.

For example, the arithmetic function 15d may calculate the amount of heat generated by the gradient magnetic field coil 2 per unit time during protocol execution by the sequence control function 13a as a measured value. In this case, the acquisition function 15c acquires the first temperature measured at any timing during protocol execution. Next, the acquisition function 15c acquires the second temperature measured after a predetermined time (one unit time) has elapsed since the acquisition of the first temperature.

Then, the computing function 15d acquires the first temperature measured at any timing during the execution of the protocol, which is acquired by the acquiring function 15c, and the second temperature measured one unit time after the acquisition of the first temperature. , the amount of heat generated by the gradient magnetic field coil 2 per unit time is calculated as a measured value. In this case, the prediction function 15b predicts the amount of heat generated by the gradient coil 2 per unit time.

The determination function 15e determines whether an abnormality has occurred in the gradient magnetic field coil 2 based on the difference between the predicted value of the calorific value calculated by the prediction function 15b and the measured value of the calorific value calculated by the arithmetic function 15d. determine whether For example, the determination function 15e determines whether an abnormality has occurred in the gradient magnetic field coil 2 based on the difference value obtained by subtracting the predicted value of the calorific value calculated by the prediction function 15b from the measured value of the calorific value calculated by the arithmetic function 15d. Determine whether or not

Specifically, the determination function 15e sets the difference value obtained by subtracting the predicted value from the actual measurement value to a first threshold value that is the upper limit value of a predetermined threshold range set for normal determination (however, the first threshold value large positive value), it is determined that the gradient magnetic field coil 2 is abnormally heating. This indicates that the actual amount of heat generated by the gradient magnetic field coil 2 is larger than the predicted amount of heat generated by the gradient magnetic field coil 2 .

Note that the first threshold is preferably different for each protocol to be executed. This is because the amount of heat generated by the gradient magnetic field coil 2 varies depending on the operating conditions (frequency, pulse sequence characteristics, etc.) set in the protocol, and the operating conditions differ depending on the protocol. Therefore, the first threshold is preferably determined according to the operating conditions of the gradient magnetic field coil 2 set in the protocol.

For example, in an AC-based pulse sequence in which an alternating-current pulse voltage is applied, the gradient magnetic field is intermittent at high speed, so eddy currents are likely to occur. Due to the generation of eddy currents, portions of the gradient magnetic field coil 2 in which the magnetic flux linkage increases are generated. When the portion generates heat, heat is generated locally, so the cooling efficiency of the cooling water is low.

Such pulse sequences are used, for example, in protocols such as "EPI". For this reason, in the AC pulse sequence, when the gradient magnetic field coil 2 heats abnormally, there tends to be a large divergence between the measured value and the predicted value.

On the other hand, in a DC pulse sequence in which a direct-current pulse voltage is applied, heat is generated as a whole, and the cooling efficiency of cooling water is high. Such pulse sequences are used, for example, in protocols such as "DWI". Therefore, in the DC pulse sequence, even if the gradient magnetic field coil 2 heats up abnormally, the difference between the actual measurement value and the predicted value is the same as when the gradient magnetic field coil 2 heats up abnormally during execution of the AC pulse sequence. smaller than it would have been.

Therefore, it is preferable to set the first threshold value larger for a protocol that executes an AC pulse sequence than for a protocol that executes a DC pulse sequence. By setting the first threshold in accordance with the characteristics of the protocol (pulse sequence) to be executed in this way, it is possible to more accurately detect abnormal heating of the gradient magnetic field coil 2 .

In addition, the causes of abnormal heat generation in the gradient magnetic field coil 2 include cold water system abnormalities (insufficient flow rate, high supply water temperature, etc.), coil abnormalities (heat generation due to increased contact resistance at connection parts, etc.), and protocol setting abnormalities (temperature settings exceeding the upper limit of management, etc.). Note that the magnitude of the difference value may change depending on the cause of abnormal heat generation, so the determination function 15e may determine the cause of abnormal heat generation according to the magnitude of the difference value.

Further, the determination function 15e determines that the difference value obtained by subtracting the predicted value from the actual measurement value falls below a second threshold value (where the second threshold value is a negative value less than 0), which is the lower limit value of the threshold range, the gradient magnetic field coil 2 It is determined that the cooling failure of This indicates that the cooling water cannot absorb the heat actually generated by the gradient magnetic field coil 2 . Note that the second threshold may be different for each protocol to be executed, like the first threshold. One of the causes of poor cooling of the gradient magnetic field coil 2 is that the cooling pipe of the gradient magnetic field coil 2 is clogged.

Further, the determination function 15e determines that the gradient magnetic field coil 2 is normal when the difference value falls within the threshold range of the second threshold≦the difference value≦the first threshold.

Note that when the determination function 15e determines that an abnormality has occurred in the gradient magnetic field coil 2, that is, when the difference value deviates from the threshold range of the second threshold≦difference value≦first threshold, the type of abnormality is determined. You can judge. In this case, the determination function 15e determines the type of abnormality from the relationship between the above-described first threshold value or second threshold value and the difference value.

For example, when the difference value exceeds the first threshold value, the determination function 15e determines that the gradient magnetic field coil 2 has a heat generation abnormality as the type of abnormality. Further, for example, when the difference value is less than the second threshold value, the determination function 15e determines that the gradient coil 2 is poorly cooled as the abnormality type.

The stop control function 15f stops the imaging by the MRI apparatus 100 by stopping the execution of the protocol when it is determined that the gradient magnetic field coil 2 has an abnormal heat generation. Specifically, when the determination function 15e determines that the gradient coil 2 is abnormal, the stop control function 15f cooperates with the sequence control function 13a to stop the execution of the protocol.

Note that the stop control function 15f may stop imaging by the MRI apparatus 100 by cooperating with the display control function 15g, which will be described later, and receiving a stop instruction from the operator. Specifically, the stop control function 15f cooperates with the display control function 15g, which will be described later, to issue a message prompting the operator to stop imaging by the MRI apparatus 100. FIG. After that, when a stop instruction is received from the operator, the stop control function 15f stops imaging by the MRI apparatus 100. FIG.

The display control function 15g controls the display of the MRI apparatus 100. FIG. For example, the display control function 15g reads the image data of the image requested by the operator from the storage circuit 11 and controls the display 10 to display the image indicated by the read image data.

Further, for example, when the judgment function 15e judges that the gradient magnetic field coil 2 has an abnormality, the display control function 15g displays a message announcing the occurrence of the abnormality on the display 10 in order to notify the operator of the fact. to control the display. The display control function 15g may notify the type of abnormality of the gradient magnetic field coil 2, such as a cold water system abnormality, a coil abnormality, a protocol setting abnormality, or a cooling failure.

Here, for example, the processing functions of the setting function 15a, the prediction function 15b, the acquisition function 15c, the calculation function 15d, the determination function 15e, the stop control function 15f, and the display control function 15g, which are the components of the processing circuit 15, are implemented by a computer. is stored in the storage circuit 11 in the form of a program that can be executed by

The processing circuit 15 reads each program from the storage circuit 11 and executes each read program, thereby realizing a function corresponding to each program. In other words, the processing circuit 15 with each program read has each function shown in the processing circuit 15 of FIG.

Note that in FIG. 1, the single processing circuit 15 includes the setting function 15a, the prediction function 15b, the acquisition function 15c, the calculation function 15d, the determination function 15e, the stop control function 15f, and the display control function 15g. However, the processing circuit 15 may be configured by combining a plurality of independent processors, and each processing function may be realized by each processor executing each program.

The term "processor" used in the above description is, for example, a CPU (central processing unit), a GPU (Graphics Processing Unit), or an application specific integrated circuit (ASIC), a programmable logic device (e.g., Circuits such as Simple Programmable Logic Device (SPLD), Complex Programmable Logic Device (CPLD), and Field Programmable Gate Array (FPGA)).

Instead of storing the program in the memory circuit 11, the program may be directly installed in the circuit of the processor. In this case, the processor implements its functions by reading and executing the program embedded in the circuit.

Also, some or all of the processing circuit 12, the processing circuit 13, the processing circuit 14, and the processing circuit 15 may be realized by the same processor.

Next, processing executed by the MRI apparatus 100 according to the first embodiment will be described. FIG. 4 is a flowchart illustrating an example of processing executed by the MRI apparatus according to the first embodiment;

First, the setting function 15a sets imaging conditions of a protocol to be executed (step S1). Specifically, the setting function 15a receives protocol parameters from the operator as protocol imaging conditions, and sets the received protocol imaging conditions.

Next, the prediction function 15b calculates a predicted value of the amount of heat generated by the gradient magnetic field coil 2 during execution of the protocol based on the imaging conditions of the protocol scheduled to be executed (step S2). Specifically, based on the protocol set by the setting function 15a and the imaging conditions of the protocol (e.g., pulse sequence characteristics, etc.), the prediction function 15b determines the amount of heat generated by the gradient magnetic field coil 2 by executing the protocol. to predict.

Next, the sequence control function 13a of the processing circuit 13 executes the protocol set by the setting function 15a (step S3). Specifically, the sequence control function 13a executes the protocol according to the imaging conditions of the protocol set by the setting function 15a.

At this time, the sequence control function 13a determines the target temperature of the cooling water based on the target temperature determination table, and generates a temperature control signal including the target temperature. The sequence control function 13 a transmits the generated temperature control signal to the gradient coil cooling device 220 .

The gradient magnetic field coil cooling device 220 cooperates with the main cooling device 300 to adjust the temperature of the cooling water according to the temperature control signal and start supplying the cooling water to the gradient magnetic field coils 2 . Thereafter, the acquisition function 15c acquires the first temperature at the start of the protocol execution by the sequence control function 13a and the second temperature at the end of the protocol execution.

Next, the arithmetic function 15d calculates the measured value of the heat generation amount of the gradient magnetic field coil 2 (step S4). Specifically, the computing function 15d determines the heat generation of the gradient magnetic field coil 2 based on the first temperature at the start of protocol execution and the second temperature at the end of protocol execution, both of which are obtained by the obtaining function 15c. Quantities are calculated as actual measurements.

Next, the determination function 15e calculates the difference between the predicted value and the measured value (step S5). Specifically, the determination function 15e subtracts the predicted value of the calorific value of the gradient magnetic field coil 2 calculated by the prediction function 15b from the measured value of the calorific value of the gradient magnetic field coil 2 calculated by the arithmetic function 15d, and obtains the difference Calculate the value.

Next, the determination function 15e determines whether or not there is an abnormality in the gradient magnetic field coil 2 based on the difference between the predicted value and the measured value (step S6). Specifically, when the calculated difference value exceeds the first threshold value or falls below the second threshold value, the determination function 15e determines that the gradient coil 2 is abnormal. Otherwise, the determination function 15e determines that the gradient magnetic field coil 2 is not abnormal.

If no abnormality has occurred in the gradient magnetic field coil 2 (step S6: No), this process is terminated. On the other hand, if there is an abnormality in the gradient magnetic field coil 2 (step S6: Yes), the stop control function 15f cooperates with the sequence control function 13a to perform control to stop scanning, and terminates this process (step S7). In addition to the stop control, the display control function 15g may notify the abnormality.

The MRI apparatus 100 according to the first embodiment described above calculates the predicted value of the heat generation amount of the gradient coil 2 based on the imaging conditions of the protocol to be executed, and supplies the predicted value from the gradient coil cooling device 220. Based on the first temperature, which is the temperature of the cooling water in the gradient coil 2, and the second temperature, which is the temperature of the cooling water returning from the gradient coil 2 to each cooling device of the main cooling device 300 and the gradient coil cooling device 220 , the actual measurement value of the heat generation amount of the gradient magnetic field coil 2 is calculated, and the presence or absence of an abnormality in the gradient magnetic field coil 2 is determined based on the difference between the predicted value and the actual measurement value.

Thereby, the amount of heat generated by the gradient magnetic field coil 2 predicted based on the imaging conditions can be compared with the actual amount of heat generated by the gradient magnetic field coil 2 calculated from the first temperature and the second temperature. If there is an abnormality in the gradient magnetic field coil 2, a deviation occurs between the predicted value and the measured value. Abnormality of the magnetic field coil 2 can be detected.

Also, the threshold value of the divergence between the predicted value and the measured value is determined based on the characteristics of the pulse sequence to be executed. When the fundamental frequency of the pulse sequence to be executed changes, the manner in which the gradient magnetic field coil 2 heats up also changes. Abnormality of the gradient magnetic field coil 2 can be detected immediately.

(Second embodiment)
The second embodiment is based on the first embodiment. The difference from the first embodiment is that the second temperature at the end of protocol execution is predicted instead of the amount of heat generated by the gradient magnetic field coil 2 . In the following, differences between the second embodiment and the first embodiment will be mainly described, and redundant description will be omitted as appropriate.

FIG. 5 is a functional block diagram showing the configuration of the MRI apparatus 100a according to the second embodiment. The MRI apparatus 100a according to the second embodiment differs from the first embodiment in that it has a prediction function 15h and a determination function 15i, and does not have an arithmetic function 15d.

The prediction function 15h is based on the operating conditions related to the operation of the gradient magnetic field coil 2 and the first temperature measured at the time of prediction, and is measured when the gradient magnetic field coil 2 is operated under the operating conditions. Predict the second temperature as the predicted value.

Specifically, the prediction function 15h, based on the protocol to be executed, flows from the gradient magnetic field coil 2 into each cooling device of the main cooling device 300 and the gradient magnetic field coil cooling device 220 when the protocol is executed by the sequence control function 13a. A predicted value of the second temperature, which is the temperature of the cooling water to be used, is calculated.

For example, the prediction function 15h calculates a predicted value of the second temperature measured by the temperature sensor 260b when the protocol (pulse sequence waveform, etc.) set by the setting function 15a is executed. Note that when a plurality of protocols are set by the setting function 15a, the prediction function 15b calculates a predicted value of the second temperature during protocol execution for each protocol.

Note that the method of predicting the second temperature during protocol execution is not particularly limited, and a known technique can be used. For example, the prediction function 15h may specify the predicted value of the second temperature using a setting table that associates the protocol with the second temperature actually measured when the protocol is executed. In addition, the prediction function 15h uses a relational expression or model that is derived from the actual measured value during execution of the protocol and is capable of deriving the second temperature during execution of the protocol from the protocol, to obtain a predicted value of the second temperature. can be derived.

Further, the prediction function 15h may correct the predicted value of the second temperature during protocol execution based on the second temperature at the start of protocol execution. This is because the temperature of the gradient magnetic field coil 2 may be increased due to the effect of the immediately preceding protocol, and as a result, the second temperature may also be increased. This makes it possible to predict the second temperature with higher accuracy.

The determination function 15i determines whether an abnormality has occurred in the gradient magnetic field coil 2 based on the temperature difference between the predicted value of the second temperature and the measured value of the second temperature measured when the gradient magnetic field coil 2 is operated. determine whether or not there is

Specifically, the determination function 15i is a predicted value of the second temperature of the gradient coil 2 calculated by the prediction function 15b from the actual measurement value of the second temperature measured at the end of the protocol execution, which is acquired by the acquisition function 15c. is subtracted to obtain the difference value. Then, the determination function 15i determines whether or not the gradient magnetic field coil 2 is abnormal based on the magnitude of the difference value.

For example, the determination function 15i determines that the gradient magnetic field coil 2 is abnormally heating when the difference value between the actual measurement value and the predicted value exceeds a first threshold value (the first threshold value is a positive value greater than 0). . Further, the determination function 15i determines that poor cooling of the gradient magnetic field coil 2 occurs when the difference value is less than the second threshold (the second threshold is a negative value less than 0).

Moreover, the determination function 15i determines that the gradient magnetic field coil 2 is normal when the difference value is in the range of the second threshold value≦the difference value≦the first threshold value. Further, the determination function 15 i may determine the type of abnormality in the gradient coil 2 . In this case, the determination function 15i determines the type of abnormality from the relationship between the first threshold value or the second threshold value and the difference value.

For example, when the difference value exceeds the first threshold, the determination function 15i determines that the gradient magnetic field coil 2 has a heat generation abnormality as the type of abnormality. Further, for example, when the difference value is less than the second threshold value, the determination function 15i determines that the gradient coil 2 is poorly cooled as the abnormality type.

Next, processing of the MRI apparatus 100a according to the second embodiment will be described. FIG. 6 is a flowchart showing an example of processing executed by the MRI apparatus 100a according to the second embodiment.

First, since step S11 is the same process as step S1 in FIG. 4, description thereof is omitted. After the process of step S11, the prediction function 15h calculates a predicted value of the second temperature during protocol execution based on the imaging conditions of the protocol scheduled to be executed (step S12). Specifically, the prediction function 15h calculates a predicted value of the second temperature during execution of the protocol based on the waveform of the pulse sequence included in the imaging conditions of the protocol set by the setting function 15a.

Since step S13 is the same process as step S3 in FIG. 4, description thereof is omitted. After the process of step S13, the acquisition function 15c acquires the measured value of the second temperature (step S14). Specifically, the acquisition function 15c acquires the second temperature at the end of execution of the protocol as the measured value of the second temperature.

Next, the determination function 15i calculates the difference between the predicted value and the measured value (step S15). Specifically, the determining function 15i subtracts the predicted value of the second temperature calculated by the predicting function 15h from the measured value of the second temperature obtained by the obtaining function 15c to calculate a difference value. Since the processes of the following processing steps S16 and S17 are the same as the processes of steps S6 and S7 in FIG. 4, description thereof is omitted.

The MRI apparatus 100a according to the second embodiment described above calculates the predicted value of the second temperature during protocol execution based on the imaging conditions of the protocol to be executed, and calculates the actual measured value of the second temperature during protocol execution. is obtained, and the presence or absence of an abnormality in the gradient magnetic field coil 2 is determined based on the difference between the predicted value and the measured value.

As a result, an abnormality in the gradient magnetic field coil 2 can be detected by directly using the measured temperature of the cooling water. That is, according to the MRI apparatus 100a according to the second embodiment, in addition to the same effects as those of the first embodiment, the effect of reducing the processing load can be expected.

Further, the MRI apparatus 100a according to the second embodiment corrects the predicted value of the second temperature during protocol execution based on the second temperature at the start of protocol execution. This makes it possible to calculate a predicted value that takes into account the effect of the protocol executed immediately before. That is, it is possible to predict the second temperature with higher accuracy.

It should be noted that the above-described first and second embodiments can be appropriately modified and implemented by changing part of the configuration or functions of the MRI apparatus 100 (MRI apparatus 100a). Therefore, hereinafter, some modifications of the above-described embodiment will be described as other embodiments. In the following description, points different from the above-described embodiment will be mainly described, and detailed description of points common to the contents already described will be omitted. Further, the modifications described below may be implemented individually or in combination as appropriate.

(Modification)
In this modification, before the protocol is executed by the sequence control function 13a, the first temperature is the temperature of the cooling water supplied to the gradient coil 2 from each of the main cooling device 300 and the gradient coil cooling device 220. A mode for adjusting the imaging conditions of the protocol will be described.

FIG. 7 is a functional block diagram showing the configuration of an MRI apparatus 100b according to a modification. The MRI apparatus 100 according to Modification 2 differs from the above embodiment in that it has a prediction function 15j and a determination function 15k, and an adjustment function 15l.

The prediction function 15j predicts the amount of heat generated by the gradient magnetic field coil 2 based on the "temperature change prediction model".

The determination function 15k calculates the predicted value of the heat generation amount of the gradient magnetic field coil 2 calculated based on the temperature rise of the gradient magnetic field coil 2 predicted by the prediction function 15j, the first temperature at the start of the protocol execution, and the temperature at the end of the protocol execution. It is determined whether or not there is an abnormality in the gradient coil 2 based on the measured value of the amount of heat generated by the gradient coil 2 calculated based on the second temperature.

The adjusting function 15l adjusts the imaging conditions of the protocol before executing the protocol. Specifically, the adjustment function 15l adjusts the duty cycle and the like included in the imaging conditions of the protocol when the first temperature before protocol execution, which is acquired by the acquisition function 15c, exceeds a predetermined third threshold. More specifically, the adjustment function 15l adjusts the duty cycle and the like in consideration of the offset from normal in the "temperature change prediction model".

Next, protocol adjustment processing executed by the MRI apparatus 100b according to the modification will be described. FIG. 8 is a flowchart showing an example of protocol adjustment processing executed by the MRI apparatus 100b according to the modification.

First, the acquisition function 15c acquires the first temperature before the protocol is executed by the sequence control function 13a (step S31). Next, the adjustment function 15l checks whether the first temperature before protocol execution exceeds the third threshold (step S32).

If the third threshold is not exceeded (step S32: No), this process is terminated. On the other hand, if the third threshold is exceeded (step S32: Yes), the adjustment function 15l adjusts the imaging conditions of the protocol and ends this process (step S33). Specifically, the adjustment function 15l adjusts the duty cycle and the like in consideration of the offset from the normal time in the "temperature change prediction model".

According to this modification, due to continuous imaging, the adjustment of the temperature of the cooling water supplied from the gradient coil cooling device 220 to the gradient magnetic field coil 2 cannot catch up, and the supplied cooling water If the temperature has risen, the amount of heat generated by the gradient magnetic field coil 2 can be suppressed by adjusting the duty cycle or the like.

Therefore, according to the MRI apparatus 100 according to the present modification, the temperature of the cooling water supplied from the gradient coil cooling device 220 to the gradient coil 2 rises, the cooling performance decreases, and the MRI apparatus 100 cannot perform imaging. Even when the possibility of being stopped is increasing, the operation of the MRI apparatus 100 can be continued by adjusting the imaging conditions of the protocol.

According to the MRI apparatus according to at least one embodiment or modified example described above, it is possible to detect abnormal heating of the gradient magnetic field coil without providing the gradient magnetic field coil with a temperature sensor.

While several embodiments of the invention have been described, these embodiments have been 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 modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention as well as the scope of the invention described in the claims and equivalents thereof.

100 MRI apparatus 2 gradient magnetic field coil 3 gradient magnetic field power supply 4 transmission coil 5 transmission circuit 6 reception coil 7 reception circuit 8 bed 8a table 9 input circuit 10 display 11 storage circuit 12 processing circuit 12a bed control function 13 processing circuit 13a sequence control function 14 processing circuit 14a image generation function 15 processing circuit 15a setting function 15b, 15h, 15j prediction function 15c acquisition function 15d calculation function 15e, 15i, 15k determination function 15f stop control function 15g display control function 200 cooling system 220 cooling for gradient magnetic field coil Apparatus 221 Heater 222 Cooling control unit 240a Valve 240b Valve 300 Main cooling device S Subject

Claims (12)

a gradient magnetic field coil that applies a gradient magnetic field;
a cooling device that cools the gradient magnetic field coil by circulating a coolant;
a measuring unit that measures a first temperature indicating the temperature of coolant flowing from the cooling device into the gradient magnetic field coil and a second temperature indicating the temperature of the coolant flowing into the cooling device from the gradient magnetic field coil;
a prediction unit that predicts, as a predicted value, an amount of heat generated by the gradient magnetic field coil generated by operating the gradient magnetic field coil under the operating condition, based on an operating condition related to the operation of the gradient magnetic field coil;
a calculation unit that calculates the amount of heat generated by the gradient magnetic field coil as a measured value based on the temperature difference between the first temperature and the second temperature measured when the gradient magnetic field coil is operated under the operating conditions; ,
a determination unit that determines whether or not an abnormality has occurred in the gradient magnetic field coil based on the difference value between the predicted value and the measured value;
A magnetic resonance imaging apparatus comprising. a gradient magnetic field coil that applies a gradient magnetic field;
a cooling device that cools the gradient magnetic field coil by circulating a coolant;
a measuring unit that measures a first temperature indicating the temperature of coolant flowing from the cooling device into the gradient magnetic field coil and a second temperature indicating the temperature of the coolant flowing into the cooling device from the gradient magnetic field coil;
The second temperature measured when the gradient magnetic field coil is operated under the operating conditions based on the operating conditions related to the operation of the gradient magnetic field coil and the first temperature measured at the time of prediction. a prediction unit that predicts as a predicted value;
An abnormality occurs in the gradient magnetic field coil based on the temperature difference between the predicted value of the second temperature and the measured value of the second temperature measured when the gradient magnetic field coil is operated under the operating conditions. A determination unit that determines whether or not
A magnetic resonance imaging apparatus comprising. The prediction unit corrects the predicted value based on the second temperature before the gradient magnetic field coil is operated under the operating conditions.
3. The magnetic resonance imaging apparatus according to claim 2. a setting unit for setting a protocol that defines an examination method for a subject;
a first control unit that operates the gradient magnetic field coil based on the operating conditions included in the protocol;
further comprising
4. The magnetic resonance imaging apparatus according to claim 1. When the difference value obtained by subtracting the predicted value from the measured value deviates from a predetermined threshold range, the determination unit determines that an abnormality has occurred in the gradient magnetic field coil.
5. The magnetic resonance imaging apparatus according to claim 1. If the difference value obtained by subtracting the predicted value from the actual measurement value exceeds a first threshold that is the upper limit value of the threshold range, the determination unit determines that the gradient magnetic field coil has an abnormal heat generation.
6. A magnetic resonance imaging apparatus according to claim 5. The first threshold is determined according to the fundamental frequency of the pulse sequence defined as the operating condition,
7. A magnetic resonance imaging apparatus according to claim 6. If the difference value obtained by subtracting the predicted value from the actual measurement value is below a second threshold value that is the lower limit value of the threshold range, the determination unit determines that poor cooling of the gradient magnetic field coil has occurred.
8. The magnetic resonance imaging apparatus according to claim 5. Further comprising a notification unit that notifies when the determination unit determines that an abnormality has occurred in the gradient magnetic field coil,
The magnetic resonance imaging apparatus according to any one of claims 5 to 8. Further comprising a second control unit that stops the operation of the gradient magnetic field coil when it is determined that the gradient magnetic field coil has an abnormal heat generation,
The magnetic resonance imaging apparatus according to any one of claims 1 to 7. a gradient magnetic field coil that applies a gradient magnetic field;
a cooling device that cools the gradient magnetic field coil by circulating a coolant;
a measuring unit for measuring a first temperature indicating the temperature of the refrigerant flowing from the cooling device into the gradient magnetic field coil and a second temperature indicating the temperature of the refrigerant flowing from the gradient magnetic field coil to the cooling device. on the computer of the imaging device,
a prediction step of predicting, as a predicted value, an amount of heat generated by the gradient magnetic field coil when the gradient magnetic field coil is operated under the operating condition, based on an operating condition related to the operation of the gradient magnetic field coil;
a calculation step of calculating the amount of heat generated by the gradient magnetic field coil as a measured value based on the temperature difference between the first temperature and the second temperature measured when the gradient magnetic field coil is operated under the operating conditions; ,
a determination step of determining whether or not an abnormality has occurred in the gradient magnetic field coil based on the difference value between the predicted value and the measured value;
program to run. a gradient magnetic field coil that applies a gradient magnetic field;
a cooling device that cools the gradient magnetic field coil by circulating a coolant;
a measuring unit for measuring a first temperature indicating the temperature of the refrigerant flowing from the cooling device into the gradient magnetic field coil and a second temperature indicating the temperature of the refrigerant flowing from the gradient magnetic field coil to the cooling device. on the computer of the imaging device,
The second temperature measured when the gradient magnetic field coil is operated under the operating conditions based on the operating conditions related to the operation of the gradient magnetic field coil and the first temperature measured at the time of prediction. a prediction step of predicting as a predicted value;
An abnormality occurs in the gradient magnetic field coil based on the temperature difference between the predicted value of the second temperature and the measured value of the second temperature measured when the gradient magnetic field coil is operated under the operating conditions. a determination step of determining whether or not
program to run.

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