JP2000023939A - Magnetic resonance imaging instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain information necessary for restarting an operation and to select an operation mode according to an inspection plan on the side of an operator by providing a means for changing a measurement operation mode when a predictive attaining temperature after a prescribed pulse sequence calculated by a temperature predicting means is executed exceeds a prescribed upper limit temperature. SOLUTION: At first, a power source is turned on, the temperature of the present inclined magnetic field coil 3 is stored and preserved in a memory within a computer 11, an operator console 12 is operated and a condition of an image pickup sequence suitable for an inspection purpose is set. After these preparations are terminated, the computer 11 calculates power to be consumed within the inclined magnetic field coil 3 from intensity of X, Y and Z inclined magnetic fields and impressing time. Next, when a rise temperature of the inclined magnetic field coil 3 when the set image pickup sequence is executed is calculated and an attaining temperature is judged to exceed an upper limit temperature, an alarm message is outputted, a selection screen of an operation mode is displayed on a display means and an operator can select either one of modes of a condition change, a standby or an intermittent execution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic resonance imaging apparatus (hereinafter, referred to as an MRI apparatus), and more particularly to an MR capable of operating in response to a temperature rise of a gradient coil.
I device.

[0002]

2. Description of the Related Art In recent years, medical diagnosis using an MRI apparatus utilizing a nuclear magnetic resonance (NMR) phenomenon has become widespread.
In this MRI apparatus, a slice selection gradient magnetic field for specifying a tomographic plane (slice) and a phase encoding gradient magnetic field for obtaining two-dimensional information in a slice are provided in order to add spatial position information to an NMR signal. And a gradient magnetic field for frequency encoding. These gradient magnetic fields are generated by supplying electric power to the gradient coil, but at the same time, the gradient coil itself generates heat.

[0003] Such heat generation not only deteriorates the inspection environment of the subject, but also causes problems such as a decrease in the mechanical strength of components for assembling the coil when the temperature exceeds the allowable temperature. For this reason, measures against heat generation control have conventionally been taken.For example, when a spin echo method is performed as a pulse sequence, the output value of a power supply for driving the gradient magnetic field coil is controlled so that the gradient magnetic field coil does not exceed the allowable temperature. Controlling.

However, high-speed imaging methods such as echo planar imaging (EPI) have been adopted in order to shorten the restraint time of the subject and to obtain a high time resolution. The applied power has increased dramatically, and the heat generation of the gradient coil has become a further problem.

In order to cope with such a problem, a temperature detecting means for detecting the temperature of the gradient coil and a temperature predicting means for predicting the temperature of the gradient coil during or at the end of the pulse sequence are provided. An MRI apparatus has been proposed in which a warning is issued when the number exceeds the limit (Japanese Patent Laid-Open No. 6-292662). In this MRI apparatus, the amount of heat generated in the gradient magnetic field coil is obtained from the resistance of the gradient magnetic field coil and the supplied current according to the pulse sequence, and the temperature is predicted, and the temperature to be increased by executing the pulse sequence is predicted in advance. Therefore, it is possible to prevent sudden stoppage due to excessive temperature during the measurement, so that waste of measurement data and time can be eliminated.

[0006]

However, in the above-mentioned MRI apparatus, an excessive temperature is predicted, a warning is issued, or the execution of the pulse sequence is simply stopped. Therefore, the restart of the operation has been performed by each operator based on their experience. Therefore, operability is further improved and MR is improved.
It is desired to effectively use the I device.

[0007] In order to meet such a demand, the present invention provides information necessary for restarting operation when the temperature of the gradient magnetic field coil is expected to rise above an allowable temperature, and also provides the operator with a necessary information. It is an object of the present invention to provide an MRI apparatus capable of selecting an operation (operation) mode according to an inspection plan or the like.

[0008]

An MRI apparatus according to the present invention comprises:
A static magnetic field generating means for applying a static magnetic field to the subject, a gradient magnetic field generating means for applying a gradient magnetic field to the subject, and a transmission system for irradiating a high-frequency magnetic field for causing nuclear magnetic resonance to an atomic nucleus of a living tissue of the subject. , A receiving system for detecting an echo signal emitted by nuclear magnetic resonance, a signal processing system for performing an image reconstruction operation using the echo signal detected by the receiving system and controlling the operation of the entire apparatus, and an obtained image Display means for displaying the measured temperature, and further, when the predicted attained temperature (Te) calculated after the execution of the predetermined pulse sequence calculated by the temperature prediction time exceeds a predetermined upper limit temperature (Tmax), the measurement operation mode is changed. Changing means.

In such a magnetic resonance imaging apparatus of the present invention, by appropriately selecting an operation mode, measurement is automatically continued or performed intermittently within a range in which the temperature of the gradient magnetic field generating means does not reach the upper limit temperature. be able to.

[0010] The temperature predicting means predicts the temperature of the gradient magnetic field generating means based on the temperature characteristics of the gradient magnetic field generating means (temperature rising characteristics and heat radiation characteristics) with the execution of the predetermined pulse sequence. By using the temperature characteristics of the gradient magnetic field generating means for temperature prediction, it is possible to predict the temperature in consideration of the entire heat capacity of the gradient magnetic field generating means. Even if there is an interruption, the temperature can be predicted.

[0011] The magnetic resonance imaging apparatus of the present invention preferably further comprises a time estimating means for calculating a time required for the gradient magnetic field generating means to change to a predetermined temperature based on the temperature rise and heat radiation characteristics of the gradient magnetic field generating means. Have. This allows you to automatically set the time for intermittent execution and standby at 1 o'clock,
As long as the temperature of the gradient magnetic field generating means does not reach the upper limit temperature,
Measurement can be automatically continued or performed intermittently in a desired operation mode.

The operation modes include a condition changing mode for changing the driving condition of the gradient magnetic field generating means, a standby mode for temporarily executing a pulse sequence, and then executing the pulse sequence halfway. An intermittent execution mode in which a pulse sequence is executed is possible, and preferably, there is provided a selection means capable of selecting any one of them.

The condition change mode includes a change in drive conditions in the same pulse sequence and a change in the imaging sequence itself. In this operation mode, the predicted attainment temperature of the gradient magnetic field generating means when the pulse sequence after the change is executed is reduced. , So that the temperature does not exceed the upper limit temperature. Thus, measurement can be continuously performed under different conditions.

The standby mode is a mode in which the measurement based on the selected pulse sequence is executed after a predetermined standby period.
The waiting period is calculated by the time estimating means, and is the time required for the temperature to drop until the gradient magnetic field generating means can be driven again.

In the intermittent execution mode, a part of the pulse sequence is executed until the predicted temperature of the gradient magnetic field generating means reaches the upper limit temperature, and the remaining pulse sequence is executed after an appropriate interruption time. The suspension time is a time required for the temperature to drop until the predicted achievement temperature predicted when the gradient magnetic field generation means executes the remaining pulse sequence becomes lower than or equal to the upper limit temperature.

In the operation mode, it is preferable to continuously irradiate the high-frequency magnetic field during the interruption period of the intermittent execution mode. Thus, the remaining measurement can be performed without breaking the steady state even during the suspension period.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The MRI apparatus of the present invention will be described below in detail with reference to embodiments. The MRI apparatus shown in FIG. 1 is an embodiment of the present invention, and includes a superconducting magnet (static magnetic field generating means) 2 for generating a uniform static magnetic field in a space where a subject 1 is placed, and a bore in the superconducting magnet 2. Gradient magnetic field coils 3 arranged to generate a gradient magnetic field whose magnetic field strength changes linearly in three axes (X, Y, Z) directions orthogonal to each other (X, Y, Z are not separately illustrated in the figure) In addition, a transmitting coil 4 for generating a high-frequency magnetic field in a space including an examination part of the subject 1 and a receiving coil 5 for detecting an echo signal induced by nuclear magnetic resonance of the examination part are incorporated.

The gradient magnetic field coils 3 in each direction have X
Gradient magnetic field power supply 6, Y gradient magnetic field power supply 7, Z gradient magnetic field power supply 8
Are connected, and the gradient coil 3 and the gradient power supply 6 are connected.
To 8 constitute a gradient magnetic field generating means. A high-frequency transmitter 9 for supplying high-frequency power is connected to the transmission coil 4 to form a transmission system, and a high-frequency receiver 10 for amplifying a received echo signal is connected to the reception coil 5 to form a reception system. ing.

The circuit units of the gradient magnetic field power supplies 6 to 8, the high frequency transmitter 9 and the high frequency receiver 10 are connected to a computer 11 for controlling the operation. The computer 11 also has a function of performing arithmetic processing on the echo signal amplified by the high-frequency receiver 10 to reconstruct an image. The computer 11 includes an operator console 12 for an operator to give an instruction, and a monitor 13 for displaying a spectrum, an image, or the like as a calculation result. The operator console 12 has a function (selection means) that enables display and selection of an operation mode in the present embodiment, in addition to normal settings such as measurement conditions and pulse sequence selection. The display of these additional functions may be performed by the monitor 13, but a display unit (not shown) may be provided on the operator console 12 itself. Hereinafter, these are collectively referred to as display means.

The computer 11 has a gradient coil 3
And a time predicting means 112 for calculating a time required for the gradient coil 3 to reach a predetermined temperature. Computer 11
Is the predicted achievement temperature (T
e) is compared with a predetermined upper limit temperature (Tmax), and based on the result, it is determined whether to execute the set pulse sequence or change the measurement. When the measurement is changed, a predetermined operation mode is displayed on the display means. Further, when a specific operation mode is selected, the transmission system, the reception system, and the gradient magnetic field generating means are controlled based on the selected operation mode.

The upper limit temperature (Tmax) is determined in consideration of the assembling accuracy and structure of the apparatus, especially the gradient magnetic field coil 3. That is, when the temperature of the gradient magnetic field coil 3 exceeds a predetermined temperature, a difference in expansion rate between the fiber reinforced plastic (FRP), which is the material of the bobbin to which the gradient magnetic field coil 3 is attached, and the copper material of the gradient magnetic field coil 3. The strain exceeds the physical limit. For this reason, it is necessary to use the MRI apparatus at a predetermined temperature or lower. Usually, such a predetermined temperature is about 70 ° C. including a margin for safety.

The temperature estimating means 111 includes the gradient coil 3
The temperature of the gradient magnetic field coil 3 is predicted as a function of the energization time, considering that the heat generated by the coil is generated due to the current supplied by the resistance of the coil. This temperature rise characteristic curve is obtained by actually driving the gradient coil 3 and measuring the actual measured value 21 of the initial temperature rise characteristic.
Can be obtained by computer simulation based on the above, and can be stored in a computer memory in advance.

For example, FIG. 2 shows the temperature change of the gradient magnetic field coil 3 when the maximum rated output of the X gradient magnetic field power supply 6 is applied to the gradient magnetic field coil (X channel) 3 with respect to the energizing time. The temperature rise characteristic curve 22 of the gradient magnetic field coil 3 is such that the initial temperature is T0, the saturation temperature when the maximum rated power of the gradient magnetic field power supply 6 is continuously applied is Tsat, and the thermal time constant of the gradient magnetic field coil 3 is k. Then, it can be expressed by the following equation (1), T = T0 + Tsat [1-exp (-t / k)] (1). Where T is the gradient coil temperature,
t is the elapsed time.

Using the same notation, the heat radiation characteristic curve 23 is expressed by the following equation (2), T = Tsat.exp [(-t-T0) / k)] (2)

The initial temperature T0 is a room temperature 25 under normal conditions.
The saturation temperature Tsat depends on the power consumption, and is 242 ° C. when the maximum gradient magnetic field rated power is continuously applied. The thermal time constant k of the gradient coil is approximately 5 hours for the gradient coil shown. In the illustrated example, that is, when the maximum rated power of the normal gradient magnetic field power supply 6 is continuously applied, the temperature reaches 98% of the saturation temperature Tsat in about 25 hours. In this case, since the temperature reaches the upper limit temperature (70 ° C.) about one hour after the start of the operation, it cannot be continuously driven at the maximum rating for 60 minutes.

In an actual measurement, a gradient magnetic field is rarely applied continuously for 60 minutes at the maximum rating in one inspection. In a routine inspection, as shown in FIG. The temperature decrease is repeated, and the upper limit temperature is not reached in one pulse sequence, but the upper limit temperature is reached by several repetitions. Therefore, in the actual temperature prediction, the predicted temperature Te after the execution of the predetermined pulse sequence is determined by combining the temperature rise characteristic curve and the heat radiation characteristic curve as described above.
Ask for.

At this time, the temperature estimating means 111 can estimate the current gradient magnetic field coil temperature from the elapsed time after the execution of the predetermined pulse sequence and the heat radiation characteristic curve by using the internal clock of the computer 11. Thus, even when the pulse sequence is executed after a predetermined interruption time or standby time, the predicted arrival temperature can be predicted.

The time estimating means 112 includes the temperature estimating means 11
Similarly to 1, the time until the specific gradient magnetic field coil temperature changes to another specific temperature is calculated (estimated) from the temperature characteristic curve. For example, if the predicted achievement temperature after the execution of a certain pulse sequence is T1, the time until the temperature of the gradient coil drops to T2 after the execution of the pulse sequence can be calculated.

Next, the MR of the present invention in such a configuration will be described.
One embodiment of the operation of the I device will be specifically described with reference to a flowchart. In the flowchart of FIG. 4, the temperature predicting unit 111 obtains a temperature that is predicted to be reached by executing the pulse sequence, and if the predicted temperature does not exceed the upper limit temperature, executes the pulse sequence as it is. If it is, the entire flow executed according to each operation mode is shown.

First, power is turned on to start the apparatus (step 41). This activation is performed by the computer 11
In accordance with the apparatus start-up program, the respective units are sequentially energized, and the operation check whether the operation state is normal is also performed. Then, the first subject is set at a predetermined position (step 42). Next, the current gradient coil 3
Is stored in the memory of the computer 11 (step 43). This temperature Tc is, if it is the first time after the start of the apparatus, the room temperature (25
° C) is input. If the apparatus has already been driven, the current temperature estimated as described later is input.

Next, the operator operates the operator console 12 to set conditions of an imaging sequence (pulse sequence) suitable for the purpose of inspection (step 44). After these preparations are completed, the computer 11 calculates the power consumed by the gradient coil 3 from the intensity of the X, Y, and Z gradient magnetic fields and the application time (step 45). For example, in the case of the pulse sequence of the spin echo method most frequently used for the inspection, the power consumed by the Z gradient coil for selecting the inspection section is 20 watts, and the Y used for the phase encoding of the echo signal in the section is used. The power consumed by the gradient coil is 35 watts on average, and the power consumed by the X gradient coil used for frequency encoding of the echo signal is 50 watts.
Watts.

In the next step 46, the computer 11
Calculates the temperature Tu at which the gradient coil 3 rises when the set imaging sequence is executed. The temperature rise Tu is obtained from the power consumption calculated in step 45 and the temperature rise characteristic curve 22 of the gradient coil 3 as shown in FIG. Then, the temperature Te reached by the gradient coil 3 is calculated by adding the temperature rise Tu to the temperature Tc of the gradient coil 3 before the execution of the imaging sequence (step 4).
7).

In the next step, it is determined whether or not the temperature Te reached by the gradient coil 3 exceeds the upper limit temperature Tmax (for example, 70 ° C.) (step 48). (Step 49),
If the temperature exceeds the upper limit temperature, the process proceeds to a step for selecting an operation mode without executing the pulse sequence (steps 50 and 51).

When the process proceeds to step 49, after the pulse sequence is executed, it is determined whether or not there is an additional test (step 52). The additional test is a case where the same subject continues the test with a different pulse sequence or a case where another subject is tested. If there is an additional inspection, the process returns to step 43, and the processes up to step 48 are executed.

However, in the second and subsequent steps 43, the current temperature Tc of the gradient magnetic field coil 3 is not room temperature but increases during the pulse-sequence execution and the elapsed time (t1) from the end of the pulse sequence. Must be taken into account due to heat radiation at the point. Therefore, a value obtained by subtracting the temperature (Td) lowered by the heat radiation during the elapsed time (t1) from the ultimate temperature Te after the execution of the pulse sequence calculated in the previous flow (step 47) is used as the new current temperature Tc. This falling temperature (T
d) can be obtained from the heat radiation characteristic curve 23 (formula (2)) and the elapsed time (t1) shown in FIG. The elapsed time can be measured by a clock 113 built in the computer 11.

In this manner, even when heat is accumulated every time the photographing is repeated, the pulse sequence can be continuously executed within a range not exceeding the upper limit temperature of 70 ° C.

If there is no additional photographing, the examination is completed,
The power of the device is cut off (step 53). In this shut-off process, the power of each unit is turned off in the order programmed in the computer 11. Also in this case, by measuring the time interval until the next start-up of the apparatus by the clock 113 built in the computer 11, it is possible to determine whether the temperature of the gradient coil 3 has been radiated to room temperature (25 ° C.). it can. In addition, an accurate value can be input as the current temperature of the gradient coil 3 input in step 43, and the practicability can be further improved.

On the other hand, if it is determined in step 48 that the expected temperature Te exceeds the upper limit temperature Tmax, a warning sound or a warning message is displayed on the display means (step 50), and the display means (selection means) is used. An operation mode selection screen is displayed, and the operator can select a condition change mode (step 500) and a standby mode (step 60).
0) or the intermittent execution mode (step 700) can be selected (step 51). Thereafter, the operation of the MRI apparatus is controlled according to this mode.

When the condition change mode is selected, the process returns to step 44, where the display means displays an input screen for conditions such as a pulse sequence, and a new condition is input. At this time, a changeable condition range may be displayed in order to eliminate trial and error of new condition setting. In this case, as shown in FIG.
Obtains a condition range for enabling the execution of the pulse sequence, and indicates this condition on the display means (step 50).
1). For example, driving conditions such as the output of the gradient magnetic field power supply and conditions relating to the pulse sequence to be executed are presented, and the operator resets the conditions by selecting the presented conditions on the operator console 12 (step 502). Then, a pulse sequence is executed based on this setting (step 503). In this case, since the condition is set so as not to exceed the upper limit temperature, the process of calculating and determining the temperature increase by a new pulse sequence (step 45)
Step 48) can be shortened or omitted.

After the execution of the pulse sequence, the flow returns to step 52 in the flow of FIG. 4, and it is determined whether or not additional imaging is to be performed continuously. As described above, in the condition change mode, measurement can be continuously performed under different conditions.

Next, when the standby mode is selected, FIG.
First, as shown in FIG.
12 calculates the time required until the gradient coil is cooled to a temperature that does not exceed the upper limit temperature even when the next pulse sequence is executed (step 601). The required cooling time t2 has a relationship shown by the following equation (3) with the current temperature Tc of the gradient coil, and is obtained by calculation using the heat radiation characteristic curve 23 (equation (2)) of FIG. {(Current temperature Tc)-(heat radiation temperature at time t2)} + Pulse sequence execution predicted rise temperature Tu <upper limit temperature Tmax (3)

Next, the computer 11 sets, for example, the calculated time t2 in a timer, and temporarily suspends the execution of the pulse sequence while the timer is operating (step 602). When the time t2 has elapsed, the execution of the pulse sequence is started (step 60).
3). At this time, before executing the pulse sequence, a step of confirming the necessity may be inserted. afterwards,
Returning to step 52, it is determined whether or not additional shooting is to be performed continuously.

In this operation mode, the temperature of the gradient coil does not exceed the allowable temperature of the gradient coil during the execution of one pulse sequence, but the temperature of the gradient coil rises during the continuous execution of the pulse sequence. This is particularly effective when the temperature exceeds the allowable temperature.

When the intermittent execution mode is selected in step 51, as shown in FIG. 7, first, a time t3 predicted to reach the upper limit temperature when the set pulse sequence is executed is calculated (step S51). 701). This upper limit temperature arrival time t3 is t3 that satisfies the following equation (4).
Is calculated by using the heating temperature characteristic curve 22 (Equation (1)) in FIG. {(Upper limit temperature Tmax)-(current temperature Tc)} ≧ Temperature rise when pulse sequence is executed for time t3 (4)

Next, the calculated time t3 is set in, for example, a timer of the computer 11 (step 702).
The pulse sequence is executed for the time during which the timer is operating (step 703). By partially executing this pulse sequence, the temperature of the gradient coil 3 reaches the upper limit temperature, and when this time t3 has elapsed, the pulse sequence being executed is interrupted halfway (step 704). The suspended state is displayed on the display means.

The interruption time (t4) until the rest of the pulse sequence is restarted can be determined so that the temperature drop due to heat radiation during the interruption time is equal to or greater than the temperature rise due to the execution of the remaining pulse sequence. In step 705, the time prediction means calculates such an interruption time (t4).

In the pulse sequence interrupted state, data obtained by the partially executed pulse sequence can be stored in the memory of the computer or other processing can be performed. Therefore, in step 705, the time until the rest of the pulse sequence is restarted together with the calculation of the interruption time (t4) may be obtained and displayed, or the time may be displayed by counting down. By providing such an additional function, the operator can perform an action during the suspension time in a planned manner. For example, post-processing such as printing a photographed image on film for an inspection that has already been completed,
Partial diagnosis can be performed.

Further, even during this interruption period, only the high-frequency magnetic field is continuously irradiated on the subject. Thus, the nuclear spin of the inspection site can be maintained in the same steady state as when the imaging is continued, so that there is no adverse effect due to the interruption of the measurement.

When the interruption time has elapsed and the remaining pulse sequence can be executed, the operator performs the remaining measurement (step 706), and then proceeds to step 5
Returning to step 2, it is determined whether or not additional shooting is to be performed continuously.

In this operation mode, even when the temperature approaches the upper limit temperature by repeating the pulse sequence several times, the inspection can be continued without restarting from the beginning by intermittently sandwiching the interrupted state.

In the above embodiment, the operation mode is selected when it is estimated that the temperature exceeds the upper limit temperature (step 51), which is preferable in terms of the degree of freedom of operation by the operator. The present invention also includes an apparatus that is set to only one of the modes in advance, and a configuration that selects any of the modes at the stage of starting the MRI apparatus. Thus, for example, in the case of repeated measurement of a routine, more efficient operation can be achieved by setting the intermittent execution mode in advance. Also, in the case of selecting at the same stage as in the above embodiment, once the mode is selected, the operation can be performed in that mode, and the same effect can be obtained.

[0052]

As described above, according to the MRI apparatus of the present invention, an operator can select a measure in the case where the temperature of the gradient magnetic field generating means may be exceeded according to an examination plan or the like. . In this case, since useful information is displayed for the operator, an appropriate judgment can be made.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of an MRI apparatus of the present invention.

FIG. 2 is a temperature characteristic curve of a gradient magnetic field coil.

FIG. 3 shows a temperature change of a gradient magnetic field coil during repeated imaging.

FIG. 4 is a flowchart showing the operation of the MRI apparatus of the present invention.

FIG. 5 is a flowchart of a condition change mode.

FIG. 6 is a flowchart of a standby mode.

FIG. 7 is a flowchart of an intermittent execution mode.

[Explanation of symbols]

 2 superconducting magnet (static magnetic field generating means) 3 gradient magnetic field coil (gradient magnetic field generating means) 4 transmitting coil (transmitting system) 5 receiving coil (receiving system) 6 X gradient magnetic field power supply (gradient magnetic field generating means) 7 Y gradient magnetic field power supply ( Gradient magnetic field generating means) 8 Z gradient magnetic field power supply (gradient magnetic field generating means) 9 High frequency transmitter (transmitting system) 10 High frequency receiver (receiving system) 11 Computer 111 Temperature predicting means 112 Time predicting means 113 Clock

Claims (5)

[Claims] 1. A static magnetic field generating means for applying a static magnetic field to a subject, a gradient magnetic field generating means for applying a gradient magnetic field to the subject, and a high frequency for causing nuclear magnetic resonance in an atomic nucleus of a biological tissue of the subject. A transmission system for irradiating a magnetic field, a reception system for detecting an echo signal emitted by the nuclear magnetic resonance, an image reconstruction operation using the echo signal detected by the reception system, and control of the operation of the entire apparatus. A magnetic resonance imaging apparatus including a signal processing system and a display unit for displaying an obtained image, further comprising: a temperature prediction unit for calculating a temperature of the gradient magnetic field generation unit; and a predetermined temperature calculated by the temperature prediction unit. Means for changing the operation mode of measurement when the predicted attained temperature (Te) after the execution of the pulse sequence of the above exceeds a predetermined upper limit temperature (Tmax). Packaging equipment. 2. The temperature predicting means predicts the temperature of the gradient magnetic field generating means based on the temperature rise and heat dissipation characteristics of the gradient magnetic field generating means in accordance with the execution of a predetermined pulse sequence. Magnetic resonance imaging equipment. 3. The apparatus according to claim 1, further comprising time estimating means for calculating a time required for said gradient magnetic field generating means to change to a predetermined temperature based on said temperature rise / heat dissipation characteristics.
The magnetic resonance imaging apparatus according to claim 1. 4. The operation mode includes: 1) a condition change mode for changing a driving condition of the gradient magnetic field generating means; 2) a standby mode for temporarily executing the pulse sequence before executing it; Run until
The magnetic resonance imaging apparatus according to any one of claims 1 to 3, further comprising: an intermittent execution mode for executing a remaining pulse sequence; and a selection unit capable of selecting any one of these modes. . 5. The apparatus according to claim 4, wherein the high-frequency magnetic field is continuously applied during a period during which the intermittent execution mode is interrupted.
The magnetic resonance imaging apparatus according to claim 1.