Magnetic resonance imaging apparatus, imaging parameter determination method, and imaging parameter determination program

Abstract

To provide a magnetic resonance imaging apparatus capable of reducing influences by difference in chemical shift amount in a slice direction between inversion pulses and flip pulses to be used by an STIR method.SOLUTION: A magnetic resonance imaging apparatus 100 is provided with a determination part. The determination part determines, on the basis of at least either a parameter related to one pulse of application of the other pulse of inversion pulses and flip pulses or intensity of a slice selecting gradient magnetic field applied together with the one pulse with respect to selection of a slice to which the one pulse are applied, at least one of a parameter related to application of the other pulse of inversion pulses and flip pulses and intensity of a slice selecting gradient magnetic field applied together with the other pulse with respect to selection of the slice to which the other pulse is applied.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Conventionally, in magnetic resonance imaging (MRI) devices, the STIR (short TI inversion recovery) method is known as a method for obtaining fat-suppressed images. It is also known that a chemical shift occurs due to the difference between the resonance frequency of water and the resonance frequency of fat. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-202122 A Summary of the Invention [Problem to be solved by the invention]

[0004] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to reduce the influence of the difference in the amount of chemical shift in the slice direction between the inversion pulse and the flip pulse used in the STIR method. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described later can also be positioned as other problems. [Means for solving the problem]

[0005] A magnetic resonance imaging apparatus according to an embodiment includes a determination unit that determines, based on at least one of a parameter related to application of one of an inversion pulse and a flip pulse and a strength of a slice selection gradient magnetic field applied together with the one pulse for selection of a slice to which the one pulse is applied, at least one of a parameter related to application of the other of the inversion pulse and the flip pulse and a strength of a slice selection gradient magnetic field applied together with the other pulse for selection of the slice to which the other pulse is applied. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a block diagram showing an example of a magnetic resonance imaging apparatus according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing an example of the relationship between the strength of a slice selection gradient magnetic field, a slice thickness, and a band of an RF pulse of the same waveform according to the embodiment. [Diagram 3] FIG. 3 is a conceptual diagram showing an example of the relationship between the strengths of the first and second slice selection gradient magnetic fields, a constant slice thickness, the band of an inversion pulse, and the band of a flip pulse, as a comparative example when the determination process according to the embodiment is not performed. [Figure 4] FIG. 4 is a diagram showing an example of an inversion pulse and a flip pulse for a chemical shift in the slice direction in the case of FIG. [Diagram 5] FIG. 5 is a diagram showing an example of a deviation amount of chemical shift in the slice direction between an inversion pulse and a flip pulse in relation to FIGS. 3 and 4. [Figure 6] FIG. 6 is a flowchart showing an example of a procedure of a determination process according to the embodiment. [Figure 7] FIG. 7 is a diagram showing an example of an inversion pulse and a flip pulse for a chemical shift in the slice direction after a determination process according to the embodiment. [Figure 8] 8 is a diagram showing an example of a relationship between slice positions excited by an inversion pulse and a flip pulse after a determination process in relation to FIG. 7 according to the embodiment; [Figure 9] FIG. 9 is a flowchart illustrating an example of a procedure of a determination process according to a modification of the embodiment. [Figure 10] FIG. 10 is a diagram showing an example of an inversion pulse and a flip pulse for a chemical shift in the slice direction after a determination process according to an application example of the embodiment. [Figure 11] 11 is a diagram showing an example of the relationship between slice positions excited by an inversion pulse and a flip pulse in relation to FIG. 10 according to an application example of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, a magnetic resonance imaging (hereinafter referred to as MRI) device, an imaging parameter determination method, and an imaging parameter determination program will be described in detail with reference to the drawings. Note that the technical idea of ​​this embodiment may be applied to various modalities combined with an MRI device, such as a PET (Positron Emission Tomography)-MRI device and a SPECT (single photon emission computed tomography)-MRI device.

[0008] (Embodiment) Fig. 1 is a diagram showing an example of an MRI apparatus 100 according to this embodiment. As shown in Fig. 1, the MRI apparatus 100 includes a static magnetic field magnet 101, a gradient magnetic field coil 103, a gradient magnetic field power supply 105, a bed 107, a bed control circuit 109, a transmission circuit 113, a transmission coil 115, a reception coil 117, a reception circuit 119, an imaging control circuit (imaging control circuit) 121, a system control circuit (system control circuit) 123, a memory 125, an input interface 127, a display 129, and a processing circuit 131.

[0009] The static magnetic field magnet 101 is a magnet formed in a hollow, approximately cylindrical shape. The static magnetic field magnet 101 generates a substantially uniform static magnetic field in the internal space. As the static magnetic field magnet 101, for example, a superconducting magnet or the like is used.

[0010] The gradient coil 103 is a coil formed in a hollow, approximately cylindrical shape, and is disposed on the inner surface side of a cylindrical cooling vessel. The gradient coil 103 receives currents individually from a gradient power supply 105 to generate gradient magnetic fields whose magnetic field strength changes along each of the mutually orthogonal X, Y, and Z axes. The gradient magnetic fields of the X, Y, and Z axes generated by the gradient coil 103 form, for example, a slice selection gradient magnetic field, a phase encoding gradient magnetic field, and a frequency encoding gradient magnetic field. The slice selection gradient magnetic field is used to arbitrarily determine an imaging cross section. The phase encoding gradient magnetic field is used to change the phase of a magnetic resonance signal (hereinafter referred to as an MR (Magnetic Resonance) signal) according to a spatial position. The frequency encoding gradient magnetic field is used to change the frequency of an MR signal according to a spatial position.

[0011] The gradient magnetic field power supply 105 is a power supply device that supplies a current to the gradient magnetic field coil 103 under the control of the imaging control circuit 121 .

[0012] The bed 107 is a device including a top plate 1071 on which the subject P is placed. The bed 107 inserts the top plate 1071 on which the subject P is placed into the bore 111 under the control of a bed control circuit 109.

[0013] The bed control circuit 109 is a circuit that controls the bed 107. The bed control circuit 109 drives the bed 107 in response to an instruction from an operator via the input / output interface 17, thereby moving the tabletop 1071 in the longitudinal direction, the up-down direction, and in some cases, the left-right direction.

[0014] The transmission circuit 113 supplies a radio frequency pulse modulated at the Larmor frequency to the transmission coil 115 under the control of the imaging control circuit 121. For example, the transmission circuit 113 has an oscillation unit, a phase selection unit, a frequency conversion unit, an amplitude modulation unit, an RF amplifier, and the like. The oscillation unit generates an RF pulse of a resonance frequency specific to a target atomic nucleus in a static magnetic field. The phase selection unit selects the phase of the RF pulse generated by the oscillation unit. The frequency conversion unit converts the frequency of the RF pulse output from the phase selection unit. The amplitude modulation unit modulates the amplitude of the RF pulse output from the frequency conversion unit according to, for example, a sinc function. The RF amplifier amplifies the RF pulse output from the amplitude modulation unit and supplies it to the transmission coil 115.

[0015] The transmission coil 115 is an RF (Radio Frequency) coil disposed inside the gradient magnetic field coil 103. In response to the output from the transmission circuit 113, the transmission coil 115 generates an RF pulse that corresponds to a high frequency magnetic field.

[0016] The receiving coil 117 is an RF coil disposed inside the gradient magnetic field coil 103. The receiving coil 117 receives an MR signal emitted from the subject P by a high frequency magnetic field. The receiving coil 117 outputs the received MR signal to a receiving circuit 119. The receiving coil 117 is, for example, a coil array having one or more, typically a plurality of coil elements. For the sake of concrete explanation, the receiving coil 117 will be described below as a coil array having a plurality of coil elements.

[0017] The receiving coil 117 may be composed of one coil element. Although the transmitting coil 115 and the receiving coil 117 are illustrated as separate RF coils in Fig. 1, the transmitting coil 115 and the receiving coil 117 may be implemented as an integrated transmitting / receiving coil. The transmitting / receiving coil corresponds to an imaging region of the subject P, and is, for example, a local transmitting / receiving RF coil such as a head coil.

[0018] The receiving circuit 119 generates a digital MR signal (hereinafter referred to as MR data) based on the MR signal output from the receiving coil 117 under the control of the imaging control circuit 121. Specifically, the receiving circuit 119 performs signal processing such as detection and filtering on the MR signal output from the receiving coil 117, and then performs analog / digital (A / D (Analog to Digital)) conversion (hereinafter referred to as A / D conversion) on the data subjected to the signal processing to generate MR data. The receiving circuit 119 outputs the generated MR data to the imaging control circuit 121. For example, the MR data is generated for each coil element and output to the imaging control circuit 121 together with a tag that identifies the coil element.

[0019] The imaging control circuit 121 controls the gradient magnetic field power supply 105, the transmission circuit 113, the reception circuit 119, etc., according to the imaging protocol output from the processing circuit 15, and performs imaging of the subject P. The imaging protocol has a pulse sequence according to the type of examination. In the imaging protocol, for example, the magnitude of the current supplied to the gradient magnetic field coil 103 by the gradient magnetic field power supply 105, the timing at which the gradient magnetic field power supply 105 supplies the current to the gradient magnetic field coil 103, the magnitude and time width of the high frequency pulse supplied to the transmission coil 115 by the transmission circuit 113, the timing at which the high frequency pulse is supplied to the transmission coil 115 by the transmission circuit 113, the timing at which the MR signal is received by the reception coil 117, etc. are defined as imaging parameters according to the pulse sequence.

[0020] For the sake of concrete explanation, the pulse sequence is assumed to be related to the STIR (short TI inversion recovery) method. The STIR method is a technique for obtaining a fat-suppressed image by utilizing the difference in relaxation time (T1) between fat and water caused by an inversion pulse (also called an inversion pulse). The pulse sequence related to the STIR method (hereinafter referred to as the STIR sequence) has a flip pulse for collecting MR signals from a subject P, and an inversion pulse applied to the subject P before applying the flip pulse to the subject P.

[0021] In this embodiment, the inversion pulse is applied together with a slice selection gradient magnetic field to the slice to which the flip pulse is applied. That is, the inversion pulse is a pulse related to fat suppression accompanied by slice selection. In the STIR sequence, when the inversion pulse is applied to the subject P together with the slice selection gradient magnetic field, the flip pulse is applied to the subject P together with the slice selection gradient magnetic field at the timing when T1 recovery by fat becomes a null point, that is, after the inversion time (hereinafter referred to as TI (Inversion Time)) has elapsed after the application of the inversion pulse. The inversion time is, for example, a value obtained by multiplying the T1 value of fat, which depends on the strength of the static magnetic field, by approximately 0.7.

[0022] The inversion pulse and flip pulse are defined by parameters including, for example, the pulse application length or band corresponding to the pulse time width and the pulse waveform. That is, the parameters related to the inversion pulse and flip pulse include the pulse application length or band, and may further include the pulse waveform. Also, the slice selection gradient magnetic field is defined by the magnitude of the current supplied to the gradient magnetic field coil for slice selection, that is, the strength of the slice selection gradient magnetic field. In the STIR method, the pulse application length or band width, the pulse waveform, and the strength of the slice selection gradient magnetic field are included in the above imaging parameters. That is, the imaging parameters include a plurality of parameters used when the imaging control circuit 121 executes the pulse sequence related to the STIR method.

[0023] Fig. 2 is a diagram showing an example of the relationship between the strength of the slice selection gradient magnetic field, the slice thickness, and the band of the RF pulse of the same waveform. As shown in Fig. 2, when the slice thickness is constant, the strength of the slice selection gradient magnetic field needs to be increased as the band of the RF pulse is widened. Widening the band of the RF pulse corresponds to shortening the application length of the RF pulse.

[0024] On the other hand, when the slice thickness is constant as shown in Fig. 2, the narrower the RF pulse band, the smaller the strength of the slice selection gradient magnetic field must be. As a result, the slice selection gradient magnetic field strength SSIS becomes smaller than the slice selection gradient magnetic field strength SSIL. Note that narrowing the RF pulse band is equivalent to lengthening the application length of the RF pulse. From the above, when excitation is performed by an RF pulse for the same slice thickness, the RF pulse band and the strength of the slice selection gradient magnetic field are proportional.

[0025] When the imaging control circuit 121 drives the gradient magnetic field power supply 105, the transmission circuit 113, the reception circuit 119, etc. to image the subject P and receives MR data from the reception circuit 119, the imaging control circuit 121 transfers the received MR data to the processing circuit 131. The imaging control circuit 121 is realized by, for example, a processor.

[0026] The term "processor" refers to circuits such as a CPU, a graphics processing unit (GPU), an application specific integrated circuit (ASIC), a programmable logic device (e.g., a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA)).

[0027] The system control circuit 123 has a processor, memories such as a ROM (Read-Only Memory) and a RAM (Random Access Memory), etc., which are not shown as hardware resources, and uses a system control function to control the MRI apparatus 100. Specifically, the system control circuit 123 reads out a system control program stored in the memory, expands it on the memory, and controls each circuit of the MRI apparatus 100 according to the expanded system control program.

[0028] For example, the system control circuit 123 reads out an imaging protocol from the memory 125 based on imaging conditions input by an operator via the input interface 127. The system control circuit 123 transmits the imaging protocol to the imaging control circuit 121 and controls imaging of the subject P. The system control circuit 123 is realized by, for example, a processor. The system control circuit 123 may be incorporated in the processing circuit 15. In this case, the system control function is executed by the processing circuit 15, and the processing circuit 15 functions as a substitute for the system control circuit 123. The processor that realizes the system control circuit 123 is similar to that described above, and therefore a description thereof will be omitted.

[0029] The memory 125 stores various programs related to the system control function executed in the system control circuit 123, various imaging protocols, imaging conditions including a plurality of imaging parameters that define the imaging protocols, etc. The memory 125 also stores the determination function 33 and the generation function 35 realized by the processing circuitry 15 in the form of a program executable by a computer.

[0030] The memory 125 also stores MR images generated by the generating function 35 and prescan images generated by a prescan such as a locator scan. The prescan images are, for example, positioning images (also called locator images) for setting an imaging field of view (hereinafter referred to as FOV (Field of view)) in a main scan, and coil sensitivity maps used for reconstructing MR images in a main scan. The memory 125 also stores the FOV set in the locator image, which is a prescan image. The memory 125 stores imaging parameters determined by the determining function 33. The memory 125 stores MR data related to a main scan using the determined imaging parameters and an algorithm for reconstructing an MR image based on the MR data.

[0031] The memory 125 may store various data received via a communication interface (not shown). For example, the memory 125 stores information on the examination order of the subject P (such as a region to be imaged, a purpose of the examination, etc.) received from an information processing system in the medical institution, such as a Radiology Information System (RIS).

[0032] The memory 125 is realized by, for example, a semiconductor memory element such as a ROM, a RAM, or a flash memory, a hard disk drive (HDD), a solid state drive (SSD), an optical disk, etc. The memory 125 may also be realized by a drive device that reads and writes various information between the memory 125 and a portable storage medium such as a compact disc (CD)-ROM drive, a digital versatile disc (DVD) drive, or a flash memory.

[0033] The input interface 127 accepts various instructions (e.g., a power-on instruction) and information input from an operator. The input interface 127 is realized by, for example, a trackball, a switch button, a mouse, a keyboard, a touch pad that performs an input operation by touching an operation surface, a touch screen in which a display screen and a touch pad are integrated, a non-contact input circuit using an optical sensor, and a voice input circuit. The input interface 127 is connected to a processing circuit 131, and converts an input operation received from an operator into an electric signal and outputs it to the processing circuit 131. Note that, in this specification, the input interface 127 is not limited to only those having physical operation parts such as a mouse and a keyboard. For example, an electric signal processing circuit that receives an electric signal corresponding to an input operation from an external input device provided separately from the MRI apparatus 100 and outputs the electric signal to a control circuit is also included as an example of the input interface 127.

[0034] The input interface 127 inputs an FOV in response to a user instruction for a pre-scan image displayed on the display 129. Specifically, the input interface 127 inputs an FOV in response to a user instruction to set a range in a locator image displayed on the display 129. In addition, the input interface 127 inputs various imaging parameters related to the main scan in response to a user instruction based on an examination order.

[0035] The display 129 displays various GUIs (Graphical User Interfaces), MR images generated by the processing circuitry 131, prescan images such as locator images, etc., under the control of the processing circuitry 131 or the system control circuitry 123. The display 129 also displays imaging parameters related to the main scan and prescan, and various information related to image processing, etc. The display 129 is realized by, for example, a display device such as a CRT display, a liquid crystal display, an organic EL display, an LED display, a plasma display, or any other display or monitor known in the art.

[0036] The processing circuit 131 is realized by, for example, the above-mentioned processor. The processing circuit 131 includes a decision function 33, a generation function 35, and the like. The processing circuit 131 that realizes the decision function 33 and the generation function 35, respectively, corresponds to a decision unit and a generation unit. Each function such as the decision function 33 and the generation function 35 is stored in the memory 125 in the form of a program executable by a computer. For example, the processing circuit 131 realizes a function corresponding to each program by reading and executing the program from the memory 125. In other words, the processing circuit 131 in a state in which each program has been read has each function such as the decision function 33 and the generation function 35.

[0037] In the above description, an example in which the "processor" reads out and executes a program corresponding to each function from the memory 125 has been described, but the embodiment is not limited to this. When the processor is, for example, a CPU, the processor realizes the function by reading out and executing a program stored in the memory 125. On the other hand, when the processor is an ASIC, instead of storing a program in the memory 125, the function is directly incorporated as a logic circuit in the circuit of the processor. Note that each processor in this embodiment is not limited to being configured as a single circuit for each processor, but may be configured as one processor by combining multiple independent circuits to realize the function. Also, although a single storage circuit has been described as storing a program corresponding to each processing function, multiple storage circuits may be distributed and arranged, and the processing circuit 131 may read out the corresponding program from each storage circuit.

[0038] The processing circuit 131, using the decision function 33, decides at least one of the following: a parameter for the application of one of the inversion pulse and the flip pulse regarding the application of the other pulse; and a strength of the slice selection gradient magnetic field applied together with the other pulse regarding the selection of the slice to which the other pulse is applied, based on at least one of the parameters for the application of the other of the inversion pulse and the flip pulse regarding the application of the other pulse; and a strength of the slice selection gradient magnetic field applied together with the other pulse regarding the selection of the slice to which the other pulse is applied.

[0039] For example, the processing circuit 131 determines at least one of the parameters of the other pulse and the strength of the slice selection gradient magnetic field applied together with the other pulse so as to reduce the deviation between the position excited by the inversion pulse and the position excited by the flip pulse, by the determination function 33. In other words, the determination function 33 determines at least one of the parameters of the other pulse and the strength of the slice selection gradient magnetic field applied together with the other pulse so as to align the position excited by the inversion pulse and the position excited by the flip pulse.

[0040] For the sake of concrete explanation, the determining function 33 is described as determining at least one of a parameter related to a flip pulse (hereinafter referred to as a first parameter) as a parameter of the one pulse and an intensity of a slice selection gradient magnetic field (hereinafter referred to as a first slice magnetic field intensity) applied together with the flip pulse as a parameter of the other pulse, a parameter related to a reverse pulse (hereinafter referred to as a second parameter) and an intensity of a slice selection gradient magnetic field (hereinafter referred to as a second slice magnetic field intensity) applied together with the reverse pulse based on at least one of the first parameter and the first slice magnetic field intensity. A process (hereinafter referred to as a determining process) for determining at least one of the second parameter and the second slice magnetic field intensity based on at least one of the first parameter and the first slice magnetic field intensity will be described later.

[0041] Fig. 3 is a conceptual diagram showing an example of the relationship between the strength SS1I of the first slice selection gradient magnetic field, the strength SS2I of the second slice selection gradient magnetic field, a constant slice thickness, a band of the flip pulse, and a band of the inversion pulse as a comparative example when the determination process is not performed. As shown in Fig. 3, when the slice thickness is constant, the strength SS2I of the second slice selection gradient magnetic field increases as the band of the inversion pulse becomes wider. Widening the band of the inversion pulse corresponds to shortening the application length of the inversion pulse.

[0042] On the other hand, when the slice thickness is constant as shown in Fig. 3, the narrower the band of the flip pulse, the smaller the strength SS1I of the first slice selection gradient magnetic field. Narrowing the band of the flip pulse corresponds to lengthening the application length of the flip pulse.

[0043] FIG. 4 is a diagram showing an example of an inversion pulse and a flip pulse for the chemical shift in the slice direction in the case of FIG. 3. A graph IPc shown in FIG. 4 shows a chemical shift in the slice direction for an inversion pulse. Also, a graph FPc shown in FIG. 4 shows a chemical shift in the slice direction for a flip pulse. The horizontal axis in the graphs IPc and FPc shows a position SS in the slice direction relative to a reference. Also, the vertical axis in the graphs IPc and FPc shows a frequency f. As shown in FIG. 4, the slice position SP and the slice thickness are the same for the slice SI to which the inversion pulse and the flip pulse are applied. In the slice SI shown in FIG. 4, water is excited by the inversion pulse and the flip pulse.

[0044] As shown in FIG. 4, for example, the first slice magnetic field strength G ss1 is the second slice magnetic field strength G ss2 In other words, the gradient of the slice selection gradient magnetic field applied together with the inversion pulse (the second slice magnetic field strength G ss2 ) is the gradient of the slice selection gradient magnetic field applied together with the flip pulse (the first slice magnetic field strength G ss1 3 and 4, the band Bw1 of the flip pulse is narrower than the band Bw2 of the inversion pulse. The band Bw1 of the flip pulse and the band Bw2 of the inversion pulse indicate frequency bands for the water component.

[0045] As shown in Figure 4, the resonance frequency of water is different from that of fat, so the fat component has a chemical shift CS along the frequency direction. FS The flip pulse band Bf1 is the frequency band Bw1 of the flip pulse, which is the frequency-direction chemical shift CS FSIn FIG. 4, flip pulse band Bf1 virtually shows the frequency band of the flip pulse for fat components. In FIG. 4, flip pulses are not applied twice, band Bw1 and band Bf1, but rather, it shows how a flip pulse is applied to water components and fat components in one application of a flip pulse. Also, in FIG. 4, flip pulse band Bf2 is a band shifted by an amount equivalent to the chemical shift CS in the frequency direction of the flip pulse band Bw2. FS The inversion pulse band Bf2 virtually represents the frequency band of the inversion pulse for the fat component. In FIG. 4, the flip pulse is not applied twice, in bands Bw2 and Bf2, but rather shows how the flip pulse is applied to the water component and the fat component in one application of the flip pulse.

[0046] As shown in FIG. 4, the bandwidth Bf2 of the inversion pulse is wider than the bandwidth Bf1 of the flip pulse. Therefore, the second slice magnetic field intensity G ss2 and the first slice magnetic field strength G ss1 Therefore, as shown in Fig. 4, the chemical shift CS SD and the chemical shift CS in the slice direction in the flip pulse. SD The shift amount is different from that of the range DIf in the slice direction in which the fat components are excited by the inversion pulse. As a result, the range DIf in the slice direction in which the fat components are excited by the flip pulse is different from the range DFf in the slice direction in which the fat components are excited by the flip pulse. In FIG. 4, the size of the range DIf and the size of the range DFf are the same.

[0047] In Figure 4, the chemical shift CS SD is extremely large, and the present embodiment is not limited to the example of FIG.

[0048] As shown in FIG. 4, the smaller the strength of the slice selection magnetic field, in other words, the smaller the inclination of the slice selection magnetic field in the slice direction, the larger the shift amount of the chemical shift in the slice direction. ss1 and the second slice magnetic field strength G ss2 are different, the range DIf and the range DFf are shifted by a shift amount CSd in the slice direction as shown in Fig. 4. In other words, in the situation shown in Fig. 4, the excitation position of fat by the inversion pulse and the excitation position of fat by the flip pulse are shifted by a shift amount CSd.

[0049] Fig. 5 is a diagram showing the amount of deviation CSd between the range DIf and the range DFf with respect to Fig. 3 and Fig. 4. The symbol IP shown in Fig. 5 indicates the range Dw in the slice direction of water excited by application of an inversion pulse to a slice SI and the range DIf in the slice direction of fat excited by application of an inversion pulse. Also, the symbol FP shown in Fig. 5 indicates the range Dw in the slice direction of water excited by application of a flip pulse to a slice SI and the range DFf in the slice direction of fat excited by application of a flip pulse.

[0050] The region BEx shown in Fig. 5 indicates a region in the slice direction excited by both the inversion pulse and the flip pulse. In the region BEx, the flip pulse is applied after a time TI has elapsed since the application of the inversion pulse, so that the MR signal due to fat is suppressed. Note that the time TI is, for example, the time at which the MR signal due to fat becomes null, but the time TI is not limited to this.

[0051] As shown in Fig. 4 and Fig. 5, when the waveforms (bandwidth, etc.) of the inversion pulse and the flip pulse are significantly different, the chemical shift in the slice direction for the fat component cannot be ignored. For example, the region FEx shown in Fig. 5 indicates a region in the slice direction that is not excited by the inversion pulse but is excited for the first time by the flip pulse. That is, in the region FEx, the excitation by the inversion pulse is not performed. Therefore, even if the flip pulse is applied after the time TI has elapsed from the application of the inversion pulse, the MR signal due to fat in the region FEx is not suppressed like the region BEx. As a result, poor fat suppression or uneven fat suppression occurs.

[0052] That is, in STIR for the same slice, the first slice magnetic field strength G ss1 and the second slice magnetic field strength G ss2 In other words, due to the difference in band between the inversion pulse and the flip pulse, image quality degradation such as poor fat suppression and a change in the null point may occur. In the determination process, imaging parameters for suppressing the image quality degradation are determined.

[0053] The processing circuitry 131 acquires MR data (hereinafter referred to as prescan data) generated by a prescan on the subject P from the receiving circuitry 119, arranges the data in k-space, and generates a prescan image based on the prescan data arranged in k-space using the generating function 35. The generating function 37 stores the generated prescan image (locator image and sensitivity map) in the memory 125. The generating function 37 generates an MR image (hereinafter referred to as main scan image) based on MR data collected by a main scan using the STIR method. The main scan image may be generated using a sensitivity map, and an existing reconstruction method can be used, so a description thereof will be omitted.

[0054] The determination process executed by the MRI apparatus 100 of this embodiment configured as above will be described with reference to Figs. 6 to 8. Fig. 6 is a flow chart showing an example of the procedure of the determination process. In this embodiment, the first slice magnetic field strength Gss1 and the second slice magnetic field strength G ss2 , the first slice magnetic field strength G ss1 If they are the same, the determination process is not carried out.

[0055] (Decision making process) (Step S601) The processing circuitry 131 acquires imaging parameters related to the STIR pulse sequence in the main scan for the subject P by the determination function 33. The imaging parameters are set in advance according to the examination order so as to realize imaging conditions such as the slice position, slice thickness, and flip angle in the STIR method. The imaging parameters may be acquired by an acquisition function separately provided in the processing circuitry 131.

[0056] (Step S602) The processing circuitry 131 determines, by the determination function 33, the second slice magnetic field strength G ss2 , the first slice magnetic field strength G ss1 For example, the first slice magnetic field strength G ss1 and the second slice magnetic field strength G ss2 In the case shown in FIG. 3 or FIG. 4, the determination function 33 determines the second slice magnetic field strength G ss2 The magnetic field strength of the first slice is G ss1 As a result, the strength of the slice selective gradient magnetic field applied together with the inversion pulse approaches the strength of the slice selective gradient magnetic field applied together with the flip pulse. In other words, the process in this step makes the slope indicating the slice selective gradient magnetic field in the graph IPc and the slope indicating the slice selective gradient magnetic field in the graph FPc approach each other. The determination function 33 determines the first slice magnetic field strength G ss1 The second slice magnetic field strength G ss2 The second slice magnetic field intensity G ss2 The magnetic field strength of the first slice is G ss1 The process of approaching the second slice magnetic field strength G ss2 and the first slice magnetic field strength G ss1and the second slice magnetic field intensity G ss2 and the first slice magnetic field strength G ss1 This includes a process of reducing the difference between

[0057] (Step S603) The processing circuit 131 determines the region FEx, the first slice magnetic field strength G ss1 The second slice magnetic field strength G ss2 Based on the slice thickness and slice position SP to which the flip pulse is applied, the determination function 33 determines a waveform parameter related to the inversion pulse. The waveform parameter is, for example, a parameter related to the shape of the envelope of the inversion pulse. Specifically, the determination function 33 determines the determined second slice magnetic field strength G ss2 Based on the slice thickness and slice position SP to which the flip pulse is applied, the band of the inversion pulse is determined. Next, the determination function 33 determines the application length of the inversion pulse based on the determined band of the inversion pulse. For example, the determination function 33 determines the band of the inversion pulse so as to approach the band of the flip pulse. That is, the determination function 33 determines the application length of the inversion pulse so as to approach the application length of the flip pulse. Note that bringing the band or application length of the inversion pulse close to the band or application length of the flip pulse includes making the band or application length of the inversion pulse the same as the band or application length of the flip pulse, and reducing the difference between the band or application length of the inversion pulse and the band or application length of the flip pulse even if they are not the same.

[0058] The second slice magnetic field intensity G determined by the determination function 33 ss2 The application length of the inversion pulse may be determined based on the slice thickness and slice position SP to which the flip pulse is applied. That is, the determination function 33 determines the application length of the inversion pulse based on the determined second slice magnetic field intensity G ss2The band and application length of the inversion pulse adjusted based on the slice thickness and slice position SP to which the flip pulse is applied may be determined as new parameters related to the inversion pulse. Note that, although the band Bw1 of the flip pulse is narrower than the band Bw2 of the inversion pulse in Fig. 4, this determination process is applicable even if the band Bw1 of the flip pulse is wider than the band Bw2 of the inversion pulse.

[0059] (Step S604) The processing circuit 131 updates the parameters of the inversion pulse in the imaging parameters to the determined parameters of the inversion pulse by the determination function 33. In addition, the determination function 33 updates the second slice magnetic field strength G ss2 is the determined second slice magnetic field strength G ss2 As a result, the determination function 33 updates the imaging parameters to have the determined parameters and the second slice magnetic field strength. With the above, the determination process is completed. After the determination process is completed, the imaging control circuit 121 executes a main scan by STIR using the updated imaging parameters.

[0060] FIG. 7 is a diagram showing an example of an inversion pulse and a flip pulse for a chemical shift in the slice direction after a determination process. A graph ADIc shown in FIG. 7 shows a chemical shift along the slice direction for an inversion pulse. Also, a graph ADFc shown in FIG. 7 shows a chemical shift along the slice direction for a flip pulse. The horizontal axis in the graphs ADIc and ADFc indicates a position SS in the slice direction relative to a reference. Also, the vertical axis in the graphs ADIc and ADFc indicates a frequency f. As shown in FIG. 7, the slice position SP and the slice thickness are the same for the slice SI to which the inversion pulse and the flip pulse are applied.

[0061] As shown in Figure 7, the resonance frequency of water is different from that of fat, so the chemical shift CS FSThe flip pulse band Bf1 is the frequency band Bw1 of the flip pulse, which is the frequency-direction chemical shift CS FS In FIG. 7, flip pulse band Bf1 virtually shows the frequency band of the flip pulse for fat components. In FIG. 7, flip pulses are not applied twice, in bands Bw1 and Bf1, but rather, it shows how a flip pulse is applied to water components and fat components in one application of a flip pulse. Also, in FIG. 7, the inversion pulse band ADBf2 is a band shifted by an amount equivalent to the chemical shift CS in the frequency direction of the inversion pulse band ADBw2. FS The inversion pulse band ADBf2 virtually represents the frequency band of the inversion pulse for the fat component. In FIG. 7, the flip pulse is not applied twice, in bands ADBw2 and ADBf2, but rather shows how the flip pulse is applied to the water component and the fat component in one application of the flip pulse.

[0062] As shown in FIG. 7, for example, the center frequency and the bandwidth in the band Bf1 of the flip pulse and the band ADBf2 of the inversion pulse after the determination process are the same, and the first slice magnetic field strength G ss1 and the second slice magnetic field strength ADG after the determination process ss2 Therefore, as shown in Fig. 7, the range ADIf in the slice direction in which the fat components are excited by the inversion pulse after the determination process is the same as the range DFf.

[0063] That is, the range ADIf overlaps with the range DFf as shown in Fig. 7. That is, after the determination process, the deviation amount CSd described in Fig. 4 is eliminated as shown in Fig. 7. In other words, as shown in Fig. 7, the excited position of fat by the inversion pulse after the determination process coincides with the excited position of fat by the flip pulse.

[0064] According to the processing of steps S602 and S603, as shown in FIG. 7, the processing circuitry 131 determines, by the determination function 33, imaging parameters of the pulse sequence in the STIR method so as to reduce the shift in the slice direction between the position excited by the inversion pulse and the position excited by the flip pulse (in other words, so as to reduce the shift amount Csd), i.e., so as to align the position excited by the inversion pulse and the position excited by the flip pulse.

[0065] In Figure 7, the chemical shift CS SD is extremely large, and the present embodiment is not limited to the example of FIG.

[0066] Fig. 8 is a diagram showing the positional relationship between the range ADIf and the range DFf with respect to Fig. 7. The symbol IP shown in Fig. 8 indicates the range Dw in the slice direction of water excited by application of an inversion pulse to a slice SI, and the range ADIf in the slice direction of fat excited by application of an inversion pulse after the determination process. Also, the symbol FP shown in Fig. 8 indicates the range Dw in the slice direction of water excited by application of a flip pulse to a slice SI, and the range DFf in the slice direction of fat excited by application of a flip pulse.

[0067] The region ABEx shown in Fig. 8 indicates a region in the slice direction excited by both the inversion pulse and the flip pulse after the determination process. In the region ABEx, the flip pulse is applied after the time TI has elapsed since the application of the inversion pulse after the determination process, so that the MR signal due to fat is suppressed. Therefore, according to this embodiment, the influence on the image quality of the image generated by STIR can be reduced.

[0068] In this embodiment, the second slice magnetic field intensity G ss2 , the first slice magnetic field strength G ss1 The second slice magnetic field strength G ss2However, the procedure of the determination process is not limited to this. For example, as a modified example of this embodiment, the processing circuitry 131 determines the first slice magnetic field intensity G ss1 The second slice magnetic field strength G ss2 The first slice magnetic field strength G ss1 The parameters of the flip pulse (such as its application length) may be determined based on the above.

[0069] According to the MRI apparatus 100 of the embodiment described above, based on at least one of the parameters related to application of one of the inversion pulse and the flip pulse and the intensity of the slice selection gradient magnetic field applied together with the one pulse for selection of the slice to which the one pulse is applied, at least one of the parameters related to application of the other of the inversion pulse and the flip pulse and the intensity of the slice selection gradient magnetic field applied together with the other pulse for selection of the slice to which the other pulse is applied is determined. For example, according to the present MRI apparatus 100, at least one of the parameters of the other pulse and the intensity of the slice selection gradient magnetic field applied together with the other pulse is determined so as to reduce the deviation (deviation amount CSd) between the position excited by the inversion pulse and the position excited by the flip pulse.

[0070] Specifically, according to the MRI apparatus 100 of this embodiment, at least one of the parameters of the other pulse and the intensity of the slice selective gradient magnetic field applied together with the one pulse is determined so as to align the position excited by the inversion pulse with the position excited by the flip pulse. More specifically, based on at least one of the parameters of the flip pulse as the parameters of the one pulse and the intensity of the slice selective gradient magnetic field applied together with the flip pulse, at least one of the parameters of the inversion pulse and the intensity of the slice selective gradient magnetic field applied together with the inversion pulse is determined as the parameters of the other pulse.

[0071] From these facts, according to the MRI apparatus 100 of this embodiment, as shown in Fig. 7 and Fig. 8, by adjusting the imaging parameters based on the strength of the slice selection gradient magnetic field, etc., the excitation position of fat by the inversion pulse and the excitation position of fat by the flip pulse can be automatically adjusted in the chemical shift in the slice direction. That is, according to the MRI apparatus 100 of this embodiment, before performing the STIR method using the inversion pulse with the application of the slice selection gradient magnetic field, the excitation position of fat by the inversion pulse and the excitation position of fat by the flip pulse can be aligned (matched) based on the imaging parameters set in advance in the imaging conditions. In other words, the band (application length) of the inversion pulse can be adjusted in conjunction with the parameters of the flip pulse (RF pulse) set in the imaging conditions, and the amount of chemical shift in the slice direction can be matched.

[0072] From the above, the MRI apparatus 100 can reduce the deviation of the slice selection position of fat components due to the chemical shift along the slice direction in the inversion pulse and the flip pulse, and can improve the uneven fat suppression in the magnetic field nonuniform region and the fluctuation of TI where T1 recovery by fat becomes null. As a result, the MRI apparatus 100 allows the user to appropriately select the flip pulse (imaging pulse) without being aware of the change in the degree of fat suppression. In addition, the MRI apparatus 100 is less susceptible to the influence of static magnetic field nonuniformity, can reduce the poor fat suppression occurring in the off-center, and can obtain more stable image quality for the MR images generated by the STIR method.

[0073] (Modification) In the above embodiment, step S603 is executed after step S602, but the present embodiment is not limited to this. The determination process in this modified example will be described below with reference to FIG.

[0074] Fig. 9 is a flow chart showing an example of a procedure sound of the decision process in this modified example. As shown in Fig. 9, steps S601 and S604 are the same processes as those in the flow chart shown in Fig. 6, and therefore the description thereof will be omitted.

[0075] (Step S602') The processing circuit 131 determines the parameters of the waveform related to the inversion pulse so as to align the band of the inversion pulse with the band of the flip pulse by the decision function 33. In this way, the band of the inversion pulse is aligned with the band of the flip pulse. Note that the decision function 33 may align the band of the inversion pulse so as to completely match the band of the flip pulse, or may align the band of the inversion pulse so as to approach the band of the flip pulse even if they do not completely match.

[0076] (Step S603') The processing circuit 131 determines the gradient magnetic field strength G of the inversion pulse so that the slice thickness is uniform between the inversion pulse and the flip pulse by the determination function 33. ss2 That is, the determination function 33 determines the first slice magnetic field strength G ss1 The second slice has a magnetic field strength of G ss2 The second slice magnetic field strength G ss2 Next, the process of step S604 is executed. The effect of this modification is the same as that of the embodiment, and therefore the description will be omitted. In step S602′, the band of the flip pulse is aligned with the band of the inversion pulse, and in step S603′, the second slice magnetic field intensity G ss2 First slice magnetic field strength G ss1 may be brought closer to each other.

[0077] (Application example) This application example aims to further stabilize the image quality of an MR image generated using the STIR method. In this application example, the processing circuitry 131 first determines, by the determination function 33, the first slice magnetic field strength G ss1 The second slice magnetic field strength ADG ss2 Determine the second slice magnetic field strength ADG ss2The determination of is the same as in the embodiment, so a description thereof will be omitted.

[0078] Next, the determination function 33 determines the parameters of the inversion pulse so that the slice thickness for the application of the inversion pulse includes the slice thickness for the application of the flip pulse. That is, according to this application example, the strength (gradient) of the slice selection gradient magnetic field is made uniform between the inversion pulse and the flip pulse, and the inversion pulse is applied to a slice that is thicker than the flip pulse. Therefore, in this application example, the band of the inversion pulse is different from the band of the flip pulse, and the band of the inversion pulse is wider than the band of the flip pulse. The parameters determined for this application example will be described below with reference to FIG. 10.

[0079] Fig. 10 is a diagram showing an example of an inversion pulse and a flip pulse for a chemical shift in the slice direction after the determination process. A graph AEIc shown in Fig. 10 shows a chemical shift along the slice direction for the inversion pulse, a band of the inversion pulse determined by the determination process, and a slice thickness ESI to which the inversion pulse is applied. Also, a graph ADFc shown in Fig. 10 shows a chemical shift along the slice direction for the flip pulse.

[0080] The horizontal axis of the graphs ADIc and ADFc shown in Fig. 10 indicates the position SS in the slice direction relative to the reference. The vertical axis of the graphs ADIc and ADFc indicates the frequency f. ST in Fig. 10 indicates the slice thickness of the slice to which the flip pulse is applied. As shown in Fig. 10, the slice thickness ESI to which the inversion pulse is applied is thicker than the slice thickness ST to which the flip pulse is applied.

[0081] 10, the processing circuit 131 determines the band AEBw2 of the inversion pulse, in other words, the application length of the inversion pulse, by the determination function 33, so that the slice thickness ESI related to the application of the inversion pulse includes the slice thickness ST related to the application of the flip pulse. That is, the determination function 33 determines the band AEBw2 of the inversion pulse to be a band that includes the band Bw1 of the flip pulse and is wider than the band Bw1 of the flip pulse. In other words, the determination function 33 determines the parameters (band or application length) of the inversion pulse so that the slice thickness to which the inversion pulse is applied is thicker than the band ADBw2 of the inversion pulse shown in FIG. 7.

[0082] As shown in Figure 10, the resonance frequency of water is different from that of fat, so the chemical shift CS FS The flip pulse band Bf1 is the frequency band Bw1 of the flip pulse, which is the frequency-direction chemical shift CS FS 10, the flip pulse band Bf1 virtually shows the frequency band of the flip pulse for the fat component. In FIG. 10, the flip pulse is not applied twice, in bands Bw1 and Bf1, but shows how the flip pulse is applied to the water component and the fat component in one application of the flip pulse.

[0083] In addition, in FIG. 10, the band AEBf2 of the inverted pulse is a band AEBw2 of the inverted pulse that is chemically shifted in the frequency direction by CS FS 10. The inversion pulse band AEBf2 virtually represents the frequency band of the inversion pulse for the fat components. In FIG. 10, flip pulses are not applied twice, in bands AEBw2 and AEBf2, but rather, one flip pulse is applied to the water components and fat components, as shown in FIG. 10.

[0084] As shown in FIG. 10, the band AEBf2 of the inversion pulse after the determination process is wider than the band Bf1 of the flip pulse. In addition, the first slice magnetic field strength G ss1 and the second slice magnetic field strength ADG after the determination process ss2 is the same as. Therefore, as shown in Fig. 10, the range AEIf in the slice direction in which fat components are excited by the inversion pulse after the determination process includes the range DFf. That is, as shown in Fig. 10, the excitation position of fat in the slice direction by the inversion pulse after the determination process includes the excitation position of fat in the slice direction by the flip pulse.

[0085] In Figure 10, for ease of explanation, the chemical shift CS SD is extremely large, and the present embodiment is not limited to the example of FIG.

[0086] Fig. 11 is a diagram showing an example of the positional relationship between the range AEIf and the range DFf with respect to Fig. 10. The symbol IP shown in Fig. 11 indicates the range Dw in the slice direction of water excited by application of an inversion pulse to a slice SI, and the range AEIf in the slice direction of fat excited by application of an inversion pulse after the determination process. Also, the symbol FP shown in Fig. 11 indicates the range Dw in the slice direction of water excited by application of a flip pulse to a slice SI, and the range DFf in the slice direction of fat excited by application of a flip pulse.

[0087] As shown in Fig. 11, the range AEIf includes the region ABEx. In the region ABEx, the flip pulse is applied after the time TI has elapsed since the application of the inversion pulse after the determination process, so that the MR signal due to fat is suppressed. Therefore, according to this application example, the influence on the image quality of the image generated by STIR can be further reduced.

[0088] According to the MRI apparatus 100 of the application example of the above-mentioned embodiment, the intensity of the slice selective gradient magnetic field applied together with the inversion pulse is determined so as to approach the intensity of the slice selective gradient magnetic field applied together with the flip pulse, and the parameter (band or application length) of the inversion pulse is determined so that the slice thickness ESI related to the application of the inversion pulse includes the slice thickness ST related to the application of the flip pulse. That is, according to the MRI apparatus 100 of the application example, the intensity of the slice selective gradient magnetic field (the gradient of the slice selective gradient magnetic field shown in FIG. 10) can be made uniform between the inversion pulse and the flip pulse, and the band of the inversion pulse can be made wider than that of the flip pulse.

[0089] This makes it possible to reduce the loss of application of the inversion pulse to the slice to which the flip pulse is applied, even if the slice profile of the inversion pulse (hereinafter referred to as the inversion pulse profile) for the position of the slice to which the inversion pulse is applied is imperfect. In addition, increasing the slice thickness by the inversion pulse to the range AEIf can reduce the occurrence of flow ghosts (also called flow artifacts) in the MR images generated by STIR.

[0090] From the above, according to this application example, it is possible to further suppress deterioration in image quality in an MR image generated by STIR, and to further stabilize the image quality of the MR image. Other effects of this application example are similar to those of the embodiment, and therefore description thereof will be omitted.

[0091] When the technical idea of ​​the embodiment is realized by the imaging parameter determination method, the parameters of one of the inversion pulse and the flip pulse in the application of the one of the pulses and the strength of the slice selection gradient magnetic field applied together with the one of the pulses in relation to the selection of the slice to which the one of the pulses is applied are obtained, and at least one of the parameters of the other of the inversion pulse and the flip pulse in the application of the other of the pulses and the strength of the slice selection gradient magnetic field applied together with the other of the pulses in relation to the selection of the slice to which the other of the pulses is applied is determined based on at least one of the parameters of the other of the pulses and the strength of the slice selection gradient magnetic field applied together with the other of the pulses. The procedure and effects of the determination process of this imaging parameter determination method are the same as those described in the embodiment, and therefore the description will be omitted.

[0092] When the technical idea of ​​this embodiment is realized by an imaging parameter determination program, the imaging parameter determination program causes a computer to acquire parameters of one of an inversion pulse and a flip pulse when the one pulse is applied and the strength of a slice selection gradient magnetic field applied together with the one pulse for selecting a slice to which the one pulse is applied, and determine at least one of parameters of the other of an inversion pulse and a flip pulse when the other pulse is applied and the strength of a slice selection gradient magnetic field applied together with the other pulse for selecting a slice to which the other pulse is applied, based on at least one of the parameters of the one pulse and the strength of the slice selection gradient magnetic field applied together with the one pulse.

[0093] For example, the determination process can be realized by installing the information processing program in a computer in a modality such as the MRI apparatus 100 or a PACS server, and developing the program in memory. In this case, the program that can cause the computer to execute the method can be stored in a storage medium such as a magnetic disk (hard disk, etc.), an optical disk (CD-ROM, DVD, etc.), or a semiconductor memory and distributed. The procedure and effect of the determination process by the imaging parameter determination program are the same as those in this embodiment, and therefore will not be described.

[0094] According to at least one of the embodiments described above, it is possible to reduce the influence of the difference in the amount of chemical shift in the slice direction between the inversion pulse and the flip pulse used in the STIR method.

[0095] Although some embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations of embodiments can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0096] 33 Decision function 35 Generation function 100 Magnetic resonance imaging device 101 Static magnetic field magnet 103 Gradient magnetic field coil 105 Gradient magnetic field power supply 107 Bed 109 Bed Control Circuit 111 Boa 113 Transmitting circuit 115 Transmitting Coil 117 Receiving coil 119 Receiving circuit 121 Imaging control circuit 123 System Control Circuit 125 Memory 127 Input Interface 129 Display 131 Processing circuit

Claims

1. A determination unit is provided which determines at least one of a parameter related to application of one of the inversion pulse and the flip pulse and a strength of a slice selection gradient magnetic field applied together with the one pulse for selection of the slice to which the one pulse is applied, based on at least one of a parameter related to application of the other of the inversion pulse and the flip pulse and a strength of a slice selection gradient magnetic field applied together with the other pulse for selection of the slice to which the other pulse is applied; The determination unit is determining an intensity of a slice selection gradient magnetic field applied together with the inversion pulse so as to be close to an intensity of a slice selection gradient magnetic field applied together with the flip pulse; determining parameters of the inversion pulse such that a slice thickness for application of the inversion pulse encompasses a slice thickness for application of the flip pulse; Magnetic resonance imaging device.

2. The determination unit determines at least one of a parameter of the other pulse and a strength of a slice selection gradient magnetic field applied together with the other pulse so as to reduce a deviation between a position excited by the inversion pulse and a position excited by the flip pulse.

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

3. The determination unit determines at least one of a parameter of the other pulse and a strength of a slice selection gradient magnetic field applied together with the other pulse so as to align a position excited by the inversion pulse with a position excited by the flip pulse.

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

4. The parameters include the application length or bandwidth of the pulse.

4. A magnetic resonance imaging apparatus according to claim 1.

5. The inversion pulse is a pulse for fat suppression with slice selection.

5. A magnetic resonance imaging apparatus according to claim 1.

6. The determination unit determines, based on at least one of a parameter related to the flip pulse as a parameter of the one pulse and a strength of a slice selection gradient magnetic field applied together with the flip pulse, at least one of a parameter related to the inversion pulse as a parameter of the other pulse and a strength of a slice selection gradient magnetic field applied together with the inversion pulse.

6. A magnetic resonance imaging apparatus according to claim 1.

7. Obtaining parameters of one of an inversion pulse and a flip pulse in applying the one of the pulses, and a strength of a slice selection gradient magnetic field applied together with the one of the pulses for selecting a slice to which the one of the pulses is applied; determining at least one of a parameter of the other pulse of the inversion pulse and the flip pulse in application of the other pulse and a strength of a slice selection gradient magnetic field applied together with the other pulse for selection of the slice to which the other pulse is applied, based on at least one of a parameter of the one pulse and a strength of a slice selection gradient magnetic field applied together with the one pulse; Determining the strength of the slice selection gradient magnetic field includes determining the strength of the slice selection gradient magnetic field applied together with the inversion pulse so as to be close to the strength of the slice selection gradient magnetic field applied together with the flip pulse; determining parameters of the inversion pulse includes determining parameters of the inversion pulse such that a slice thickness associated with application of the inversion pulse encompasses a slice thickness associated with application of the flip pulse; A method for determining imaging parameters.

8. On the computer, Obtaining parameters of one of an inversion pulse and a flip pulse in applying the one of the pulses, and a strength of a slice selection gradient magnetic field applied together with the one of the pulses for selecting a slice to which the one of the pulses is applied; The present invention realizes determining at least one of the parameters of the other pulse in the application of the other pulse of the inversion pulse and the flip pulse, and the intensity of the slice selection gradient magnetic field applied together with the other pulse with respect to the selection of the slice to which the other pulse is applied, based on at least one of the parameters of the one pulse and the intensity of the slice selection gradient magnetic field applied together with the other pulse; Determining the strength of the slice selection gradient magnetic field includes determining the strength of the slice selection gradient magnetic field applied together with the inversion pulse so as to be close to the strength of the slice selection gradient magnetic field applied together with the flip pulse; determining parameters of the inversion pulse includes determining parameters of the inversion pulse such that a slice thickness associated with application of the inversion pulse encompasses a slice thickness associated with application of the flip pulse; Imaging parameter determination program.

Images