Magnetic resonance imaging apparatus, magnetic resonance imaging method, and magnetic resonance imaging program

Abstract

Read out and output the saturated MR signal excited by a saturated RF pulse. [Solution] The magnetic resonance imaging apparatus according to this embodiment includes a prepulse execution unit, a readout unit, a main acquisition execution unit, and an output unit. The prepulse execution unit irradiates a saturated RF pulse as a prepulse. The readout unit spatially selectively reads out the saturated magnetic resonance signal corresponding to the signal excited by the saturated RF pulse. The main acquisition execution unit performs main acquisition, which includes irradiating an excitation RF pulse that is a different RF pulse from the saturated RF pulse, after the irradiation of the saturated RF pulse. The output unit outputs the main acquisition data and the saturated magnetic resonance signal collected by the main acquisition.

Description

Technical Field

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

Background Art

[0002] Conventionally, for the purpose of suppressing unnecessary magnetic resonance signals, saturation pulses are often used in magnetic resonance imaging (hereinafter referred to as MRI (Magnetic Resonance Imaging)). A saturation pulse is an RF pulse applied to a subject before collecting MR signals for diagnosis. For example, in magnetic resonance spectroscopy (MRS), a water suppression pulse may be used as a saturation pulse. Also, in various MRIs, a fat suppression pulse may be used as a saturation pulse.

[0003] The above saturation pulse is mainly implemented in a slice non-selective manner. At this time, after the application of the saturation pulse, a spoiler is applied to the subject. That is, the sequence related to the saturation pulse is composed of a combination of a slice non-selective saturation pulse and a spoiler (spoiler gradient magnetic field or RF spoiler). When an OVS (Outer Volume Suppression) pulse or a Sat band (Saturation bands) pulse is used as a saturation pulse, a slice selection gradient magnetic field is applied to the subject together with the application of the saturation pulse, and then a spoiler is applied to the subject. At this time, the sequence related to the saturation pulse is composed of a combination of a slice selection gradient magnetic field, a saturation pulse, and a spoiler.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] [Non-Patent Document 1] Haase A, Frahm J, Ha”nicke W, Matthaei D., 1H NMR chemical shift selective (CHESS) imaging. Phys Med Biol, 1985;30:341-344. [Non-Patent Document 2] Felmlee JP, Ehman RL., Spatial presaturation: a method for suppressing flow artifacts and improving depiction of vascular anatomy in MR imaging. Radiology 1987;164:559-564. [Overview of the project] [Problems that the invention aims to solve]

[0006] One of the problems that the embodiments disclosed herein and in the drawings aim to solve is to read out and output a saturated magnetic resonance signal corresponding to a signal excited by a saturated RF pulse. However, the problems that the embodiments disclosed herein and in the drawings aim to solve 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]

[0007] The magnetic resonance imaging apparatus according to this embodiment includes a pre-pulse execution unit, a readout unit, a main acquisition execution unit, and an output unit. The pre-pulse execution unit irradiates with a saturated RF pulse as a pre-pulse. The readout unit spatially selectively reads out the saturated magnetic resonance signal corresponding to the signal excited by the saturated RF pulse. The main acquisition execution unit performs main acquisition, which includes irradiating with an excitation RF pulse that is a different RF pulse from the saturated RF pulse, after the irradiation of the saturated RF pulse. The output unit outputs the main acquisition data and the saturated magnetic resonance signal collected by the main acquisition. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a block diagram showing the configuration of an MRI apparatus according to an embodiment. [Figure 2] Figure 2 is a diagram showing an example of a sequence related to pre-collection in an embodiment. [Figure 3] Figure 3 shows an example of a gradient spoiler related to the readout of a saturated MR signal, relating to an embodiment. [Figure 4] Figure 4 is a diagram illustrating an embodiment and showing an example of a gradient spoiler different from that shown in Figure 3. [Figure 5] Figure 5 shows an example of a pre-acquisition sequence PA including multiple saturated RF pulses, relating to an embodiment. [Figure 6] Figure 6 is a diagram illustrating an embodiment, showing an example of a second MR image of a subject, a first MR image along the Z direction, and a first MR image along the Y direction. [Figure 7] Figure 7 shows an example of an embodiment, illustrating the region of a saturated RF pulse with a limited saturation area and the second MR image of subject P. [Figure 8] Figure 8 shows an example of a pre-acquisition sequence in which the target imaging site is the liver, according to an embodiment. [Figure 9] Figure 9 is a flowchart showing an example of the procedure for processing using a saturated MR signal according to the embodiment. [Figure 10] Figure 10 is a diagram showing an example of a selection screen related to an embodiment. [Modes for carrying out the invention]

[0009] The following describes embodiments of a magnetic resonance imaging apparatus (hereinafter referred to as an MRI apparatus), a magnetic resonance imaging method, and a magnetic resonance imaging program with reference to the drawings. In principle, the contents described in each embodiment can also be applied to other embodiments. In the following embodiments, parts with the same reference numerals perform similar operations, and redundant explanations will be omitted as appropriate.

[0010] (Embodiment) Figure 1 is a block diagram showing the configuration of an MRI apparatus 100 according to an embodiment. As shown in Figure 1, the MRI apparatus 100 comprises a static magnetic field magnet 101, a static magnetic field power supply 102, a gradient magnetic field coil 103, a gradient magnetic field power supply 104, a patient table 105, a patient table control circuit 106, a transmitting coil 107, a transmitting circuit 108, a receiving coil 109, a receiving circuit 110, a sequence control circuit 120, and a computer 130 (also referred to as an image processing device). Note that the MRI apparatus 100 does not include a subject P (e.g., a human body). Furthermore, the configuration shown in Figure 1 is merely an example. For example, the parts within the sequence control circuit 120 and the computer 130 may be integrated or separated as appropriate.

[0011] The static magnetic field magnet 101 is a hollow, substantially cylindrical magnet that generates a static magnetic field in its internal space. The static magnetic field magnet 101 is, for example, a superconducting magnet and is excited by the supply of current from the static magnetic field power supply 102. The static magnetic field power supply 102 supplies current to the static magnetic field magnet 101. The static magnetic field magnet 101 may also be a permanent magnet, in which case the MRI device 100 does not need to have the static magnetic field power supply 102. The static magnetic field power supply 102 may also be provided separately from the MRI device 100.

[0012] The gradient magnetic field coil 103 is a coil formed in a hollow substantially cylindrical shape and is disposed inside the static magnetic field magnet 101. The gradient magnetic field coil 103 is formed by combining three coils corresponding to the X, Y, and Z axes orthogonal to each other, and these three coils are individually supplied with current from the gradient magnetic field power supply 104 to generate a gradient magnetic field in which the magnetic field strength changes along the X, Y, and Z axes. The gradient magnetic fields along the X, Y, and Z axes generated by the gradient magnetic field coil 103 are, for example, the slice gradient magnetic field Gs, the phase encoding gradient magnetic field Ge, and the readout gradient magnetic field Gr. The gradient magnetic field power supply 104 supplies current to the gradient magnetic field coil 103.

[0013] The bed 105 includes a top plate 105a on which the subject P is placed, and under the control of the bed control circuit 106, the top plate 105a is inserted into the cavity (imaging aperture) of the gradient magnetic field coil 103 with the subject P placed thereon. Usually, the bed 105 is installed such that the longitudinal direction is parallel to the central axis of the static magnetic field magnet 101. The bed control circuit 106 drives the bed 故 to move the top plate 105a in the longitudinal direction and the vertical direction under the control of the computer 130.

[0014] The transmission coil 107 is disposed inside the gradient magnetic field coil 103 and generates a high-frequency magnetic field upon receiving an RF pulse from the transmission circuit 108. The transmission circuit 供 supplies an RF pulse corresponding to the Larmor frequency determined by the type of the target atom and the magnetic field strength to the transmission coil 107.

[0015] The reception coil 109 is disposed inside the gradient magnetic field coil 103 and receives a magnetic resonance signal (hereinafter referred to as an MR (Magnetic Resonance) signal) emitted from the subject P due to the influence of the high-frequency magnetic field. When the reception coil 109 receives the MR signal, the received MR signal is output to the reception circuit 110.

[0016] Note that the above-described transmission coil 107 and reception coil 109 are merely examples. The transmission coil 107 and reception coil 109 may be configured by combining one or more of a coil having only a transmission function, a coil having only a reception function, or a coil having both transmission and reception functions.

[0017] The reception circuit 110 detects the MR signal output from the reception coil 109 and generates MR data based on the detected MR signal. Specifically, the reception circuit 110 generates MR data by digitally converting the MR signal output from the reception coil 109. Further, the reception circuit 110 transmits the generated MR data to the sequence control circuit 120. Note that the reception circuit 110 may be provided on the gantry device side including the static magnetic field magnet 101, the gradient magnetic field coil 103, and the like.

[0018] The sequence control circuit 120 performs imaging of the subject P by driving the gradient magnetic field power supply 104, the transmission circuit 108, and the reception circuit 110 based on the sequence information transmitted from the computer 130. Here, the sequence information is information defining the procedure for performing imaging, and may be simply referred to as a sequence. The sequence information defines the strength of the current supplied by the gradient magnetic field power supply 104 to the gradient magnetic field coil 103 and the timing of supplying the current, the intensity of the RF pulse supplied by the transmission circuit 108 to the transmission coil 107 and the timing of applying the RF pulse, the timing at which the reception circuit 110 detects the MR signal, and the like.

[0019] [[ID=If]]

[0020] ​Furthermore, the sequence control circuit 120 drives the gradient power supply 104, the transmitting circuit 108, and the receiving circuit 110 to image the subject P. After receiving MR data from the receiving circuit 110, it transfers the received MR data to the computer 130.

[0021] The functions realized by the sequence control circuit 120 will now be explained. The sequence control circuit 120 has a pre-pulse execution function 121, a read function 122, a main acquisition execution function 123, and an output function 124. Each processing function realized by the pre-pulse execution function 121, the read function 122, the main acquisition execution function 123, and the output function 124 is stored in the memory mounted on the sequence control circuit 120 in the form of a program that can be executed by the sequence control circuit 120. The sequence control circuit 120 is a processor that realizes the functions corresponding to each program by reading the program from memory and executing it. In other words, the sequence control circuit 120 in the state where each program has been read will have the functions shown in the sequence control circuit 120 in Figure 1.

[0022] In Figure 1, the processing functions realized by a single sequence control circuit 120, consisting of a prepulse execution function 121, a readout function 122, a main acquisition execution function 123, and an output function 124, are described. However, the sequence control circuit 120 may be configured by combining multiple independent processors, and each processor may realize the functions by executing a program. In other words, each of the above functions may be configured as a program, and one sequence control circuit 120 may execute each program, or specific functions may be implemented in dedicated, independent program execution circuits.

[0023] In the above explanation, the term "processor" refers to circuits such as CPUs, application-specific integrated circuits, and programmable logic devices (e.g., Simple Programmable Logic Devices (SPLDs), Complex Programmable Logic Devices (CPLDs), and Field Programmable Gate Arrays (FPGAs)). A processor performs its functions by reading and executing programs stored in memory.

[0024] Alternatively, instead of saving the program in memory, the program may be directly embedded within the processor's circuitry. In this case, the processor functions by reading and executing the program embedded within the circuitry. Similarly, the bed control circuit 106, the transmission circuit 108, the reception circuit 110, and the processing circuit 150 described later are also composed of the above-mentioned processor and other electronic circuits.

[0025] The sequence control circuit 120 irradiates the subject P with a saturated RF pulse (which may also be called a saturated prepulse) as a prepulse using the prepulse execution function 121. Specifically, the prepulse execution function 121 irradiates the subject P with a saturated RF pulse via the transmission circuit 108 and the transmission coil 107. At this time, the prepulse execution function 121 may also control the gradient magnetic field power supply 104 to apply a slice selection magnetic field to the subject P in conjunction with the irradiation of the saturated RF pulse. The sequence control circuit 120 that realizes the prepulse execution function 121 corresponds to the prepulse execution unit.

[0026] The following explains the difference between saturated RF pulses and excited RF pulses. An excited RF pulse is, for example, an excited RF pulse used for data acquisition. A saturated RF pulse is an RF pulse that is irradiated at a different time than the excited RF pulse. Also, unlike the excited RF pulse, a phase-ignoring RF pulse is often used as a saturated RF pulse. For these reasons, saturated RF pulses and excited RF pulses are different RF pulses because they differ in irradiation time (timing), etc.

[0027] Specifically, a saturated RF pulse is irradiated onto subject P before the execution of the main acquisition sequence (hereinafter referred to as the main acquisition sequence), which includes an excitation RF pulse. The saturated RF pulse corresponds to, for example, a CHESS (Chemical Shift Selective) pulse (water suppression pulse, fat suppression pulse) without slice selection. The saturated RF pulse is predetermined according to the requirements for acquiring the MR signal in the main acquisition sequence. For example, the bandwidth of the saturated RF pulse and the slice selection intensity applied together with the saturated RF pulse must satisfy the conditions imposed by the purpose of the main acquisition sequence.

[0028] On the other hand, regarding navigation RF pulses used in navigator acquisition, the bandwidth and slice selectivity intensity of the navigation RF pulse can be appropriately designed to match the purpose of navigator acquisition. Therefore, saturated RF pulses and navigation RF pulses are RF pulses with different purposes and design philosophies.

[0029] The sequence control circuit 120, using the readout function 122, spatially selectively reads out the saturated magnetic resonance signal corresponding to the signal excited by the saturated RF pulse. Spatial selectivity corresponds, for example, to the application of the readout gradient magnetic field. The signal excited by the saturated RF pulse corresponds to the MR signal generated from the subject P by irradiating the subject P with the saturated RF pulse. In other words, the saturated RF pulse is used to suppress MR signals related to water or fat, but it generates an MR signal (saturated MR signal) by exciting the substance to be suppressed. To put it another way, the saturated RF pulse is a type of excitation, and the saturated MR signal contains information necessary for calibration and correction of the acquired data. For this reason, the saturated MR signal may also be called saturated RF pulse information.

[0030] The readout function 122 reads out the saturated MR signal using a spoiler applied to the subject P after irradiation with a saturated RF pulse and before the execution of this acquisition sequence. The spoiler is, for example, a gradient spoiler or an RF spoiler. For simplicity of explanation, the spoiler will be described below as a gradient spoiler. The irradiation with a saturated RF pulse and the readout of the saturated MR signal are included in the pre-acquisition performed before this acquisition sequence. Pre-acquisition includes the application of a spoiler gradient magnetic field (also called a gradient spoiler) that disperses the saturated MR signal. In this case, the spoiler gradient magnetic field includes a readout gradient magnetic field corresponding to the readout of the saturated MR signal.

[0031] Specifically, the readout function 122 controls the gradient magnetic field power supply 104 after irradiation with a saturated RF pulse to apply a spoiler gradient magnetic field to the subject P. At this time, the readout function 122 reads out the saturated MR signal via the receiving coil 109 and the receiving circuit 110. The readout saturated MR signal is digitized by the receiving circuit 110 and may therefore be referred to as saturated MR data.

[0032] Figure 2 shows an example of a pre-acquisition sequence (hereinafter referred to as the pre-acquisition sequence) PA. The pre-acquisition sequence PA in Figure 2 has multiple saturation RF pulses SRP, a gradient spoiler SP related to the readout and spoiler of the saturation MR signal, and a slice-selective gradient magnetic field. As shown in Figure 2, the multiple saturation RF pulses SRP include, as an example, two water suppression pulses WSP and six OVS pulses OP. In Figure 2, the readout function 122 uses the gradient spoiler SP to read out multiple saturation MR signals corresponding to the two water suppression pulses WSP and the six OVS pulses OP, respectively.

[0033] Figure 3 shows an example of a gradient spoiler SP for reading out a saturated MR signal. As shown in Figure 3, the gradient spoiler SP includes a read gradient magnetic field RO and an end spoiler ESP. The end spoiler ESP is a gradient magnetic field that spoils the saturated MR signal after the read gradient magnetic field RO is applied. The bidirectional arrow DA in the read gradient magnetic field RO shown in Figure 3 indicates the readout period of the saturated MR signal. As shown in Figure 3, the read gradient magnetic field RO includes a gradient magnetic field PA (hereinafter referred to as the adjustment gradient magnetic field) that adjusts the starting position of the readout of the saturated MR signal. The application period of the adjustment gradient magnetic field PA corresponds, for example, to the time during which the starting position of the readout of the saturated MR signal can be set to the edge of k-space.

[0034] In Figure 3, if the time interval between a saturated RF pulse and the next saturated RF pulse, and the time interval between the last saturated RF pulse and the excitation RF pulse, is longer than the application period of the tuned gradient magnetic field PA, the tuned gradient magnetic field PA is set in the pre-acquisition sequence PA. The tuned gradient magnetic field PA and gradient spoiler SP shown in Figure 3 are set by the setting function 134 described later.

[0035] Furthermore, for example, the water suppression pulse WSP in Figure 2 is irradiated onto subject P in a non-slice-selective manner. Also, the OVS pulse OP in Figure 2 is irradiated onto subject P together with the slice-selective gradient magnetic field SSG. In this case, the readout line of the saturated MR signal in k-space becomes a single line in space, with the edge of k-space as the starting position for reading out the saturated MR signal for each of the multiple saturated RF pulses SRP.

[0036] Figure 4 shows an example of a gradient spoiler SP different from that shown in Figure 3. As shown in Figure 4, the readout gradient field RO does not include a tuning gradient field, unlike in Figure 3. In Figure 4, an example of a gradient spoiler SP corresponds to a case where the time interval between a saturation RF pulse and the next saturation RF pulse, and the time interval between the last saturation RF pulse and the excitation RF pulse, are shorter than the application period of the tuning gradient field PA.

[0037] The gradient spoiler SP shown in Figure 4 is configured by the setting function 134 described later. In this case, the readout line of the saturated MR signal in k-space becomes a single line in space, with the center of k-space as the starting position for reading the saturated MR signal for each of the multiple saturated RF pulses SRP. That is, the readout line of the saturated MR signal corresponds to an example of a half scan.

[0038] The readout function 122 may also read out saturated MR signals along multidimensional readout lines such as EPI (echo planar imaging) or spiral scan. The gradient spoiler SP that realizes the multidimensional readout lines is set by the setting function 134 described later. In this case, the set readout gradient magnetic field includes the multidimensional readout gradient magnetic field.

[0039] Figure 5 shows an example of a pre-acquisition sequence PA including multiple saturated RF pulses (SRP). As shown in Figure 5, the multiple saturated RF pulses (SRP) have three water suppression pulses (WSP). The pre-acquisition sequence PA shown in Figure 5 can be used, for example, as water suppression for MRS (Multiple Resonance Systems) such as WET (water suppression enhanced through T1 effects) or VAPOR (Variable Power and Optimized Relaxations delays).

[0040] As shown in Figure 5, the gradient spoiler SP for the three water suppression pulses WSP is applied along three axes (Gx, Gy, Gz). While the gradient spoiler SP in Figure 5 is shown along three axes, it is not limited to these. For example, the gradient spoiler SP may also be applied along oblique directions such as the XY direction. In this case, the gradient spoiler SP realizes multidimensional readout lines in addition to the three axes in k-space: kx, ky, and kz, such as the (kx·ky) direction. Furthermore, the readout line of the saturated MR signal may be changed for each TR related to the saturated RF pulse.

[0041] Furthermore, the readout function 122 may read out saturated RF pulse information using a readout gradient magnetic field having a frequency set (adjusted) in accordance with the chemical shift. The frequency of the readout gradient magnetic field is set (adjusted) in accordance with the chemical shift by the setting function 134 described later. In this case, the set readout gradient magnetic field includes a multidimensional readout gradient magnetic field. The sequence control circuit 120 that realizes the readout function 122 corresponds to the readout unit.

[0042] The sequence control circuit 120, using the acquisition execution function 123, performs the acquisition, which includes irradiation with an excitation RF pulse EP, which is a different RF pulse from the saturation RF pulse, after irradiation with a saturation RF pulse. For example, according to the acquisition sequence, the acquisition execution function 123 irradiates the subject P with the excitation RF pulse EP via the transmission circuit 108 and the transmission coil 107.

[0043] Next, the acquisition execution function 123 controls the gradient magnetic field power supply 104 according to the acquisition sequence to apply various gradient magnetic fields to the subject P. The acquisition execution function 123 also collects MR signals related to this acquisition via the receiving coil 109 and the receiving circuit 110. The MR signals collected by this acquisition are converted into MR data via the receiving circuit 110. Hereinafter, the MR data collected by this acquisition will be referred to as the acquisition data. The sequence control circuit 120 that realizes the acquisition execution function 123 corresponds to the acquisition execution unit.

[0044] The sequence control circuit 120 outputs the acquired data and the saturated MR signal via the output function 124. For example, the output function 124 outputs the acquired data and the saturated MR signal to the computer 130. Specifically, the output function 124 outputs the acquired data and the saturated MR signal to the processing circuit 150. Alternatively, the output function 124 may output the acquired data and the saturated MR signal to the memory circuit 132. The sequence control circuit 120 that implements the output function 124 corresponds to the output section.

[0045] Computer 130 performs overall control of the MRI device 100 and generates images, etc. Computer 130 includes a memory circuit 132, an input device 141, a display 143, and a processing circuit 150. The processing circuit 150 has an interface function 131, a control function 133, a setting function 134, an image generation function 136, an estimation function 138, and a correction function 139.

[0046] The memory circuit 132 stores various MR data (such as the collected data and saturated MR signals) received by the processing circuit 150 having the interface function 131, and various image data generated by the image generation function 135. The memory circuit 132 also stores MR data (also called k-space data) arranged in k-space by the control function 133. For example, the memory circuit 132 can be implemented using semiconductor memory elements such as RAM (Random Access Memory) or flash memory, a hard disk, or an optical disc. The memory circuit 132 may also be referred to as memory.

[0047] The input device 141 receives various instructions and information inputs from the user. The input device 141 can be implemented by, for example, a trackball, switch buttons, a mouse, a keyboard, a touchpad that allows input operations by touching the operating surface, a touchscreen that integrates a display screen and a touchpad, a non-contact input circuit using an optical sensor, and an audio input circuit. The input device 141 is electrically connected to the processing circuit 150 and converts the input operations received from the user into electrical signals and outputs them to the processing circuit 150. The input device 141 corresponds to the input section.

[0048] In this specification, the input device 141 is not limited to those equipped with physical operating components (input interfaces) such as a mouse or keyboard. For example, an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device provided separately from the MRI device 100 and outputs this electrical signal to a control circuit is also included as an example of the input device 141. The input device 141 corresponds to the input section and may also be referred to as an input interface, operating device, etc.

[0049] The display 143, under the control of a processing circuit 150 having a control function 133, displays a GUI (Graphical User Interface) for accepting inputs such as imaging conditions, and images generated by the processing circuit 150 having an image generation function 142. The display 143 can be implemented using a display device such as a CRT display, liquid crystal display, organic EL display, LED display, plasma display, or any other display or monitor known in the art. The display 143 corresponds to the display unit.

[0050] The processing functions performed by the interface function 131, control function 133, setting function 134, image generation function 136, estimation function 138, and correction function 139 are stored in the memory circuit 132 in the form of programs that can be executed by the computer 130. The processing circuit 150 is a processor that reads the programs from the memory circuit 132 and executes them to realize the functions corresponding to each program. In other words, the processing circuit 150, in the state in which each program has been read, will have the functions shown in the processing circuit 150 in Figure 1.

[0051] In Figure 1, the processing functions performed by the interface function 131, control function 133, setting function 134, image generation function 136, estimation function 138, and correction function 139 are described as being realized by a single processing circuit 150. However, the processing circuit 150 may be composed of multiple independent processors, and each processor may realize the functions by executing a program. In other words, each of the above functions may be configured as a program, and one processing circuit 150 may execute each program, or a specific function may be implemented in a dedicated, independent program execution circuit.

[0052] In the above description, the term "processor" refers to circuits such as CPUs, GPUs, application-specific integrated circuits, and programmable logic devices (e.g., simple programmable logic devices (SPLDs), complex programmable logic devices (CPLDs), and field-programmable gate arrays (FPGAs)). The processor functions by reading and executing programs stored in the memory circuit 132.

[0053] Alternatively, instead of saving the program in the memory circuit 132, the program may be directly incorporated into the processor's circuitry. In this case, the processor functions by reading and executing the program incorporated into the circuitry. Similarly, the bed control circuit 106, transmission circuit 108, reception circuit 110, etc., are also composed of the above-mentioned processor and other electronic circuits.

[0054] The processing circuit 150 transmits sequence information to the sequence control circuit 120 via the interface function 131 and receives MR data from the sequence control circuit 120. Upon receiving MR data, the interface function 131 stores the received MR data in the memory circuit 132. For example, the interface function 131 receives the main acquired data and the saturated MR signal from the output function 124. The interface function 131 outputs the received main acquired data and saturated MR signal to the memory circuit 132 or to various functions within the processing circuit 150. The processing circuit 150 that implements the interface function 131 corresponds to the interface section.

[0055] The processing circuit 150, through its control function 133, performs overall control of the MRI device 100, controlling imaging, image generation, image display, etc. For example, the control function 133 accepts input of imaging conditions (imaging parameters, etc.) via a GUI and generates sequence information according to the accepted imaging conditions. The processing circuit 150, which has the control function 133, also transmits the generated sequence information to the sequence control circuit 120. The processing circuit 150 that implements the control function 133 corresponds to the control unit.

[0056] The processing circuit 150, using the setting function 134, performs settings (adjustments) for the timing and intensity of the spoiler regarding the readout of the saturated MR signal. For example, the setting function 134 determines whether or not the adjustment gradient magnetic field can be set in the pre-acquisition sequence PA before setting. Specifically, the setting function 134 compares the time interval between a saturated RF pulse and the next saturated RF pulse, and the time interval between the last saturated RF pulse and the excitation RF pulse, with a predetermined threshold. The predetermined threshold is, for example, the application time of the gradient spoiler SP (the sum of the application time of the readout gradient magnetic field RO and the application time of the end spoiler ESP).

[0057] If the time interval between a saturated RF pulse and the next saturated RF pulse, and the time interval between the last saturated RF pulse and the excitation RF pulse, exceeds a predetermined threshold, the setting function 134 sets the readout gradient field RO, which includes the adjustment gradient field PA, to the gradient spoiler SP, as shown in Figure 3. If the time interval between a saturated RF pulse and the next saturated RF pulse, and the time interval between the last saturated RF pulse and the excitation RF pulse, is below a predetermined threshold, the setting function 134 sets the readout gradient field RO, which does not include the adjustment gradient field PA, to the gradient spoiler SP, as shown in Figure 4.

[0058] Furthermore, the setting function 134 sets the integral value of the spoiler gradient magnetic field over the application time of the spoiler gradient magnetic field to match the design value set according to this acquisition sequence. For example, as shown in Figure 3, if the gradient spoiler SP includes an adjustment gradient magnetic field PA, the setting function 134 increases the intensity of the gradient magnetic field at the end spoiler ESP immediately after the readout gradient magnetic field RO to cancel out the negative portion of the adjustment gradient magnetic field PA and to compensate for the decrease in gradient magnetic field intensity due to the readout gradient magnetic field RO.

[0059] Furthermore, as shown in Figure 4, if the gradient spoiler SP does not include an adjustable gradient magnetic field PA, the setting function 134 increases the gradient magnetic field strength at the end spoiler ESP immediately following the read gradient magnetic field RO to compensate for the decrease in gradient magnetic field strength caused by the read gradient magnetic field RO. Therefore, the setting function 134 increases the gradient magnetic field strength at the end spoiler ESP immediately following the read gradient magnetic field RO to match the design value.

[0060] Furthermore, the setting function 134 sets (adjusts) the frequency of the readout gradient field RO in accordance with the chemical shift. For example, in the case of fat suppression, assuming the chemical shift of fat, the MR signal from fat is suppressed by the fat suppression pulse. Since the chemical shift of fat is 3.5 ppm, the center frequency of the saturated RF pulse is shifted by 3.5 ppm. In order to match the center frequency of the readout gradient field RO frequency to the center frequency of the saturated RF pulse, the setting function 134 sets the center frequency of the readout gradient field RO frequency by shifting it by, for example, 3.5 ppm, similar to the saturated RF pulse.

[0061] Furthermore, the setting function 134 may set the timing of application of the excitation RF pulse EP and the timing of application of various gradient magnetic fields in this acquisition sequence according to the respiratory state of the subject P estimated by the estimation function 138 described later. At this time, the sequence control circuit 120 executes this acquisition sequence at the set timing by the acquisition execution function 123.

[0062] The setting function 134 sets a first reception gain for reading the saturated MR signal and a second reception gain for collecting the current data. The first reception gain and the second reception gain are different. If the saturated MR signal is smaller than the MR signal at the time of collecting the current data, for example, the first reception gain will be greater than the second reception gain.

[0063] For example, the setting function 134 sets the gain of the gain amplifier preceding the ADC (Analog-to-Digital Converter) in the receiving circuit 110 to the first receiving gain when the pre-acquisition sequence PA is executed. The setting function 134 also sets the gain of the said gain amplifier in the receiving circuit 110 to the second receiving gain when the current acquisition sequence is executed. The processing circuit 150 that implements the setting function 134 corresponds to the setting unit.

[0064] The processing circuit 150 generates a first magnetic resonance image (hereinafter referred to as the first MR image) by performing a one-dimensional inverse Fourier transform on the saturated MR signal along the readout direction of the saturated MR signal using the image generation function 136. In other words, the image generation function 136 generates the first MR image by applying a one-dimensional inverse Fourier transform to the saturated MR signal. The first MR image corresponds to a one-dimensional image in which multiple pixels are arranged along an axis corresponding to the readout direction of the saturated MR signal.

[0065] In other words, the information obtained from the saturated MR signal corresponds to data obtained by applying one-dimensional modulation to the integral in three-dimensional space. For example, when a readout gradient magnetic field is applied in the X direction and the saturated MR signal is read out, the first MR image contains a mixture of signals related to the Y and Z directions. In this case, the pixel values ​​are separated in the X direction in the first MR image. Furthermore, the first MR image becomes a one-dimensional MR image relating to, for example, water or fat, depending on the type of saturated RF pulse.

[0066] Furthermore, the image generation function 136 generates a second magnetic resonance image (hereinafter referred to as the second MR image) by performing an inverse Fourier transform on the acquired data. For example, if the acquired data is arranged in a two-dimensional k-space, the image generation function 136 generates a two-dimensional second MR image by applying a two-dimensional inverse Fourier transform to the acquired data. Also, if the acquired data is arranged in a three-dimensional k-space, the image generation function 136 generates a three-dimensional second MR image by applying a three-dimensional inverse Fourier transform to the acquired data. The generation of the first and second MR images can be performed using known methods, so a detailed explanation is omitted. The processing circuit 150 that implements the image generation function 136 corresponds to the image generation unit.

[0067] The processing circuit 150 estimates the movement of subject P using the first MR image via the estimation function 138. For example, the estimation function 138 estimates the movement of subject P by comparing multiple first MR images. Specifically, the estimation function 138 estimates the one-dimensional movement corresponding to the application direction and the substance to be saturated for each TR by comparing two time-series adjacent first MR images where the direction of application of the readout gradient magnetic field is the same (for example, by comparing high-luminance regions or by comparing difference regions of inter-frame difference images). For example, if the substance to be saturated is water and the application direction is the X-axis, the estimation function 138 estimates the movement of the water from the presence or absence of water along the X-axis by calculating the change in pixel values ​​along the X-axis. The accuracy of the movement estimation can be improved by setting the strength of the readout gradient magnetic field related to the saturated MR signal to be weak.

[0068] Figure 6 shows an example of the second MR image IM2 of subject P, the first MR image BA along the Z direction (the axis direction of subject P), and the first MR image APA along the Y direction (the anterior-posterior direction of subject P). The first MR image BA along the Z direction is a one-dimensional MR image based on the saturated MR signal read out using a readout gradient magnetic field along the Z direction. Similarly, the first MR image APA along the Y direction is a one-dimensional MR image based on the saturated MR signal read out using a readout gradient magnetic field along the Y direction.

[0069] As shown in Figure 6, the first MR image includes the presence or absence of a signal in the direction to which the readout gradient magnetic field is applied. The first MR image may also contain aliasing depending on the direction to which the readout gradient magnetic field is applied. However, the estimation function 138 estimates the movement of a substance (e.g., water or fat) according to the type of saturated RF pulse by comparing multiple first MR images. The accuracy of this movement estimation is higher in the long axis direction (Z direction).

[0070] Furthermore, as shown in Figure 5, when multiple saturated RF pulses for water suppression for MRS are applied to the subject P in each of the three axes, multiple first MR images are generated using the multiple saturated MR signals collected for each TR. At this time, the estimation function 138 estimates the movement of the subject P in each of the three axes using the first MR images for each of the three axes. In addition, by changing the method of saturated RF pulses for each TR, it becomes possible to estimate movement in two or more dimensions. This estimation may be performed by estimating one-dimensional movement for each acquired signal, or by integrating two or more projection data to estimate movement in two or more dimensions.

[0071] The above explanation describes an example using a spatially non-selective saturation RF pulse, but the saturation RF signal may also be read out using a selective saturation RF pulse. For example, as a selective saturation RF pulse, an OVS pulse OP or Sat band as shown in Figure 2 may be used. In this case, for reading out the saturation MR signal, two axes, selective saturation and selective readout, which limit the region to be saturated, are set by the setting function 134. Because the saturation RF pulse is spatially selective, a phase shift may be significantly superimposed on the saturation MR signal. For this reason, a saturation RF pulse without phase shift is desirable. For example, either the real part or the imaginary part of the saturation RF pulse may be modulated.

[0072] Figure 7 shows an example of a saturated RF pulse region Sat, where the saturated region is limited, and the second MR image IM2 of the subject P. As shown in Figure 7, the behavior of the saturated MR signal changes depending on the selection of the readout direction, and therefore the estimated movement of the subject P also differs. For example, in the region where a selective saturated RF pulse is applied (Sat band direction), the estimation function 138 can estimate the displacement (movement) within the region Sat shown in Figure 7. Outside the region Sat shown in Figure 7, the estimation function 138 can estimate the displacement (movement) across the entire image.

[0073] Furthermore, the estimation function 138 estimates the respiratory state of subject P using the first MR image. For example, if a fat-suppressing pulse is used as the saturated RF pulse and the imaging target area is the liver, the estimation function 138 detects liver movement based on the first MR image. Specifically, if multiple saturated MR signals are collected before the execution of this acquisition sequence, the estimation function 138 estimates liver movement based on the changes in two first MR images that are temporally adjacent and have the same direction of application of the readout gradient magnetic field for the saturated MR signal.

[0074] For example, if the target area for imaging is an organ with a high fat content, the movement of the target area will result in a relative intensity relationship between the pixel values ​​in the first MR image, which will be reflected as a change in pixel values ​​in two first MR images. The estimation function 138 estimates (infers) the respiratory state of subject P based on the detected movement of the liver. Since known methods can be applied to the estimation method of the respiratory state based on the movement of the target area for imaging, an explanation will be omitted.

[0075] Figure 8 shows an example of a pre-acquisition sequence PA when the target site for imaging is the liver. As shown in Figure 8, multiple saturated RF pulses SRP have two fat-suppression pulses FSP. At this time, the estimation function 138 uses two first MR images corresponding to two saturated MR signals collected by multiple spoiler SPs corresponding to the two fat-suppression pulses FSP to detect the movement of the liver, which is the target site for imaging in the subject P.

[0076] Next, the estimation function 138 estimates the respiratory state of subject P based on liver movement. At this time, the setting function 134 sets various timings in the acquisition sequence according to the estimated respiratory state of subject P. Subsequently, the sequence control circuit 120 executes the acquisition sequence at the set timings by the acquisition execution function 123. Thus, the acquisition execution function 123 uses the estimated respiratory state of subject P to perform the acquisition in synchronization with subject P's respiration. In other words, the acquisition execution function 123 uses the saturated MR signal as a navigator for the respiratory-gated scan.

[0077] In some cases, the movement of the target area may not be clearly reflected as changes in the pixel values ​​of the two first MR images, depending on the pre-acquisition sequence PA. In this case, the sequence control circuit 120 may perform an additional calibration scan (for example, this acquisition is performed as a two-dimensional cine scan in the longitudinal direction of the body) immediately before executing the pre-acquisition sequence PA, which makes it easier to determine the respiratory state of the subject P. At this time, the estimation function 138 calculates (determines) the correspondence between the MR image based on the signals acquired by the calibration scan and the respiratory state of the subject P. Next, the estimation function 138 performs matching between the correspondence table showing this correspondence and the first MR image to estimate the respiratory state of the subject P.

[0078] In the above example, the process of estimating the respiratory state by matching with a correspondence table was described, but the method is not limited to this. For example, the estimation function 138 may input the first MR image into a pre-trained model that is trained to output the respiratory state, and estimate the respiratory state of subject P from the output of the pre-trained model. The processing circuit 150 that implements the estimation function 138 corresponds to the estimation unit.

[0079] The processing circuit 150 performs motion correction on the second MR image based on the estimated motion using the correction function 139. That is, the correction function 139 corrects the motion of the subject P in the second MR image using the shift in pixel values ​​in multiple first MR images corresponding to multiple saturated MR signals. Since known methods can be applied to the motion correction of the second MR image by the correction function 139, a detailed explanation is omitted. The processing circuit 150 that implements the correction function 139 corresponds to the correction unit.

[0080] The overall configuration of the MRI apparatus 100 according to the embodiment has been described above. Under the above configuration, the MRI apparatus 100 according to the embodiment spatially selectively reads out the saturated MR signal by applying a saturated RF pulse and performs processing that utilizes the saturated MR signal (hereinafter referred to as saturated MR signal utilization processing). Examples of saturated MR signal utilization processing include motion correction of the second MR image and use as a navigator. Below, as an example of saturated MR signal utilization processing, motion correction for the second MR image will be described.

[0081] The procedure for processing using saturated MR signals will be explained with reference to Figure 9. Figure 9 is a flowchart showing an example of the procedure for processing using saturated MR signals.

[0082] (Processing using saturated MR signal) (Step S901) Prior to using the saturated MR signal, the display 143 displays a selection screen that allows the user to choose the application of the saturated MR signal. For example, the display 143 displays on the selection screen whether or not motion correction is performed for that application, and / or whether or not it is selected as a navigator for that application. Specifically, before the execution of the pre-acquisition sequence PA and the current acquisition sequence, the processing circuit 150 causes the display 143 to display the selection screen. At this time, motion correction is selected based on instructions from the user via the input device 141.

[0083] Figure 10 shows an example of the selection screen DS. As shown in Figure 10, on the selection screen DS, the motion correction item (Motion Corr) and the water suppression item (WaterSAT) are selected as ON by the user, and the navigation item (Navigation) is selected as OFF by the user. At this time, other items such as the flip angle of the saturated RF pulse may be set by the user. Also, for example, when this acquisition sequence with respiratory synchronization is performed, on the selection screen DS, the navigation item (Navigation) and the water suppression item (WaterSAT) are selected as ON by the user, and the motion correction item (Motion Corr) is selected as OFF by the user.

[0084] (Step S902) The processing circuit 150 sets sequence information using the setting function 134. The setting function 134 sets, for example, various imaging parameters related to the pre-acquisition sequence PA and various imaging parameters related to the main acquisition sequence as sequence information. The various imaging parameters related to the pre-acquisition sequence PA include, for example, parameters related to the readout gradient magnetic field RO (intensity, application timing, application time, frequency of the readout gradient magnetic field RO), parameters related to the end spoiler ESP (intensity, application timing, application time of the end spoiler ESP), the first receiver gain, and parameters related to the saturation RF pulse (intensity, flip angle, irradiation timing, etc. of the saturation RF pulse).

[0085] Various imaging parameters related to this acquisition sequence include, for example, parameters related to various gradient magnetic fields (intensity, application timing, application time, and frequency of the gradient magnetic field Gs for slicing, Ge for phase encoding, and Gr for readout), the second receiver gain, and parameters related to the excitation RF pulse (intensity, flip angle, irradiation timing, etc. of the saturation RF pulse).

[0086] For example, the setting function 134 sets various parameters related to the current acquisition sequence based on user instructions via the input device 141. The setting function 134 also sets various parameters related to the previous acquisition sequence based on the value selected on the selection screen DS shown in Figure 10 and user instructions via the input device 141. The setting function 134 stores the set parameters in the memory circuit 132.

[0087] (Step S903) The sequence control circuit 120 irradiates the subject P with a saturated RF pulse using the pre-pulse execution function 121. For example, the pre-pulse execution function 121 irradiates the subject P with a saturated RF pulse according to various imaging parameters related to the pre-acquisition sequence (specifically, parameters related to the saturated RF pulse).

[0088] (Step S904) The sequence control circuit 120 applies a readout gradient magnetic field RO via the readout function 122 to spatially select and read out the saturated MR signal. For example, the readout function 122 applies the readout gradient magnetic field RO to the subject P according to various imaging parameters related to the pre-acquisition sequence (specifically, parameters related to the readout gradient magnetic field). As a result, the readout function 122 reads out the saturated MR signal. The sequence control circuit 120 outputs the saturated MR signal to the computer 130 via the output function 124.

[0089] (Step S905) The sequence control circuit 120 applies endo-spoiler ESP via the readout function 122. For example, the readout function 122 applies endo-spoiler ESP to the subject P according to various imaging parameters related to the pre-acquisition sequence (specifically, parameters related to endo-spoiler ESP).

[0090] (Step S906) If the saturated RF pulse in the previous acquisition sequence PA is completed (Yes in step S906), the process in step S907 is executed. If the saturated RF pulse in the previous acquisition sequence PA is not completed (No in step S906), the process from step S903 onwards is executed.

[0091] (Step S907) The sequence control circuit 120 executes the acquisition sequence and collects the acquisition data using the acquisition execution function 123. For example, the acquisition execution function 123 performs the acquisition for subject P according to various imaging parameters related to the acquisition sequence. As a result, the acquisition execution function 123 acquires the acquisition data. The sequence control circuit 120 outputs the acquisition data to the computer 130 using the output function 124.

[0092] (Step S908) If the collection of all main data related to the imaging target area is complete (Yes in step S908), the process in step S909 is executed. If the collection of all main data related to the imaging target area is not complete (No in step S908), the process from step S903 onwards is repeated.

[0093] (Step S909) The processing circuit 150 generates a first MR image based on the saturated MR signal using the image generation function 136. The image generation function 136 also generates a second MR image based on this acquired data. The image generation function 136 stores the first MR image and the second MR image in the memory circuit 132.

[0094] (Step S910) The processing circuit 150 estimates the movement of subject P based on the first MR image using the estimation function 138. Specifically, the estimation function 138 estimates the movement of subject P using two first MR images that are adjacent in time series and have the same direction of application of the read gradient magnetic field RO, i.e., two first MR images corresponding to two adjacent frames. The estimated movement of subject P corresponds, for example, to the number of pixels along the direction of application of the read gradient magnetic field RO. The estimation function 138 stores the estimated movement of subject P in the memory circuit 132.

[0095] (Step S911) The processing circuit 150 performs motion correction on the second MR image based on the estimated movement of subject P, as determined by the correction function 139. That is, the correction function 139 corrects the movement of subject P in the second MR image using the estimated movement of subject P. The correction function 139 stores the second MR image, on which motion correction has been performed, in the memory circuit 132.

[0096] The MRI apparatus 100 according to the embodiment described above performs irradiation with a saturated RF pulse SRP as a prepulse, spatially selectively reads out the saturated MR signal corresponding to the signal excited by the saturated RF pulse SRP, performs main acquisition including irradiation with an excitation RF pulse EP which is a different RF pulse from the saturated RF pulse SRp after irradiation with the saturated RF pulse, and outputs the main acquisition data and the saturated MR signal collected by the main acquisition. The MRI apparatus 100 according to the embodiment also displays a selection screen on the display 143 that allows the user to select the application of the saturated MR signal. The MRI apparatus 100 according to the embodiment also displays on the selection screen whether or not a navigator has been selected as an application.

[0097] For example, in the MRI apparatus 100 according to the embodiment, pre-acquisition, which includes irradiation with the saturated RF pulse SRP and reading out the saturated MR signal, includes the application of a spoiler gradient magnetic field that disperses the saturated MR signal, the spoiler gradient magnetic field includes a readout gradient magnetic field corresponding to the reading out of the saturated MR signal, and the MRI apparatus 100 according to the embodiment sets the integral value of the spoiler gradient magnetic field over the application time of the spoiler gradient magnetic field to match a design value set according to the main acquisition.

[0098] Furthermore, in the MRI apparatus 100 according to the embodiment, the readout gradient magnetic field RO includes an adjustment gradient magnetic field that adjusts the starting position of the readout of the saturated MR signal or a multidimensional readout gradient magnetic field that adjusts the starting position. In addition, the MRI apparatus 100 according to the embodiment sets the frequency of the readout gradient magnetic field RO in accordance with the chemical shift and reads out the saturated MR signal using the readout gradient magnetic field RO having the set frequency. Furthermore, the MRI apparatus 100 according to the embodiment sets a first reception gain for the readout of the saturated MR signal and a second reception gain for the collection of the acquired data, and the first reception gain and the second reception gain are different.

[0099] Furthermore, the MRI apparatus 100 according to the embodiment generates a first MR image by performing a one-dimensional inverse Fourier transform on the saturated MR signal along the reading direction of the saturated MR signal, generates a second MR image by performing an inverse Fourier transform on the acquired data, estimates the movement of subject P using the first MR image, and performs motion correction on the second MR image based on the estimated movement. In addition, the MRI apparatus 100 according to the embodiment estimates the respiratory state of subject P using the first MR image, and performs the acquisition in synchronization with the breathing of subject P using the estimated respiratory state.

[0100] According to the MRI apparatus 100 of this embodiment, a saturated MR signal corresponding to a signal excited by a saturated RF pulse can be read out and output. As a result, the MRI apparatus 100 of this embodiment can appropriately read out and output saturated MR signals that would otherwise be discarded without being read out, without affecting the main acquisition, thereby enabling the appropriate use of saturated MR signals containing information necessary for calibration and correction.

[0101] For example, according to the MRI apparatus 100 of the embodiment, a first MR image can be generated based on a saturated MR signal, the movement of the subject P can be estimated using the first MR image, and motion correction can be performed on the second MR image related to the acquisition using the estimated movement. Furthermore, according to the MRI apparatus 100 of the embodiment, a first MR image can be generated based on a saturated MR signal, the respiratory state of the subject P can be estimated using the first MR image, and the acquisition can be performed with respiratory synchronization using the estimated respiratory state as navigation.

[0102] Based on these considerations, the MRI apparatus 100 according to the embodiment can improve the quality of output data such as second MR images by effectively utilizing the saturated MR signal generated by the saturated RF pulse without discarding it. For example, the MRI apparatus 100 according to the embodiment eliminates the need for various RF pulses related to motion correction and respiratory synchronization, thereby reducing imaging time. At the same time, the MRI apparatus 100 according to the embodiment can reduce the burden on the subject P by shortening the examination time, and / or improve the throughput of the examination by generating an MR image with reduced artifacts caused by the movement of the subject P.

[0103] When the technical concept of the embodiment is realized by a magnetic resonance imaging method, the magnetic resonance imaging method performs irradiation with a saturated RF pulse as a prepulse, spatially selectively reads out the saturated MR signal corresponding to the signal excited by the saturated RF pulse, performs main acquisition including irradiation with an excitation RF pulse which is an RF pulse different from the saturated RF pulse after irradiation with the saturated RF pulse, and outputs the main acquisition data and the saturated MR signal collected by the main acquisition. The procedure and effect of the saturated MR signal utilization processing performed by the magnetic resonance imaging method are the same as in the embodiment, so a description is omitted.

[0104] When the technical concept in the embodiment is realized in a magnetic resonance imaging program, the program enables the computer to perform irradiation with a saturated RF pulse as a prepulse, spatially selectively read out the saturated MR signal corresponding to the signal excited by the saturated RF pulse, perform the main acquisition including irradiation with an excitation RF pulse which is a different RF pulse from the saturated RF pulse after irradiation with the saturated RF pulse, and output the main acquisition data and the saturated MR signal collected by the main acquisition.

[0105] For example, saturated MR signal utilization processing can also be achieved by installing a magnetic resonance imaging program on a computer in an MRI device and loading it into memory. In this case, the magnetic resonance imaging program that enables the computer to execute the saturated MR signal utilization processing can be stored and distributed on storage media such as magnetic disks (hard disks, etc.), optical disks (CD-ROMs, DVDs, etc.), and semiconductor memory. Furthermore, the distribution of the magnetic resonance imaging program is not limited to the above media, and may also be distributed using telecommunications functions, such as downloading via the internet. The procedure and effects of saturated MR signal utilization processing using the magnetic resonance imaging program are the same as in the embodiment, so a description will be omitted.

[0106] According to the embodiments described above, a saturated magnetic resonance signal corresponding to a signal excited by a saturated RF pulse can be read out and output.

[0107] Although embodiments have been described above, 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 variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of symbols]

[0108] 100 Magnetic Resonance Imaging System 101 Static Magnetic Field Magnet 102 Static magnetic field power supply 103 Gradient field coil 104 Gradient magnetic field power supply 105 berths 105a Top plate 106 Bed control circuit 107 Transmitter coil 108 Transmitter Circuit 109 Receiving coil 120 Sequence control circuit 121 Prepulse execution function 122 Read function 123 Main Data Collection Execution Function 124 output function 130 Computers 131 Interface Functions 132 Memory circuit 133 Control Functions 134 Settings Function 136 Image generation function 138 Estimated Function 139 Correction function 141 Input device 142 Image generation function 143 displays 150 Processing Circuits

Claims

1. A prepulse execution unit that performs irradiation with a saturated RF pulse as a prepulse, A readout unit that spatially selects and reads out the saturated magnetic resonance signal corresponding to the signal excited by the saturated RF pulse, The main acquisition execution unit performs the main acquisition, which includes the irradiation of an excitation RF pulse, which is an RF pulse different from the saturation RF pulse, after the irradiation of the saturation RF pulse. An output unit that outputs the collected data and the saturated magnetic resonance signal obtained through the aforementioned collection, A magnetic resonance imaging system equipped with the following features.

2. The pre-acquisition, which includes irradiation with the saturated RF pulse and reading out the saturated magnetic resonance signal, includes the application of a spoiler gradient magnetic field that disperses the saturated magnetic resonance signal. The spoiler gradient magnetic field includes a readout gradient magnetic field corresponding to the readout of the saturated magnetic resonance signal. The system further includes a setting unit that sets the integral value of the spoiler gradient magnetic field over the application time of the spoiler gradient magnetic field to match the design value set according to the acquisition. The magnetic resonance imaging apparatus according to claim 1.

3. The readout gradient magnetic field includes a gradient magnetic field that adjusts the starting position of the readout of the saturated magnetic resonance signal or a multidimensional readout gradient magnetic field that adjusts the starting position. The magnetic resonance imaging apparatus according to claim 2.

4. The setting unit sets the frequency of the readout gradient magnetic field in accordance with the chemical shift. The reading unit reads out the saturated magnetic resonance signal using the read gradient magnetic field having the set frequency. The magnetic resonance imaging apparatus according to claim 2 or 3.

5. An image generation unit generates a first magnetic resonance image by performing a one-dimensional inverse Fourier transform on the saturated magnetic resonance signal along the reading direction of the saturated magnetic resonance signal, and generates a second magnetic resonance image by performing an inverse Fourier transform on the acquired data. An estimation unit that estimates the movement of a subject irradiated with the saturated RF pulse using the first magnetic resonance image, A correction unit that performs motion correction on the second magnetic resonance image based on the estimated motion, The magnetic resonance imaging apparatus according to claim 1, further comprising:

6. An image generation unit generates a first magnetic resonance image by performing a one-dimensional inverse Fourier transform on the saturated magnetic resonance signal along the reading direction of the saturated magnetic resonance signal, An estimation unit that estimates the respiratory state of a subject irradiated with the saturated RF pulse using the first magnetic resonance image, Furthermore, The aforementioned collection execution unit uses the respiratory state to perform the collection in synchronization with the subject's respiration. The magnetic resonance imaging apparatus according to claim 1.

7. The system further includes a setting unit for setting a first receiving gain for reading out the saturated magnetic resonance signal and a second receiving gain for collecting the acquired data. The first receiving gain and the second receiving gain are different, The magnetic resonance imaging apparatus according to claim 1.

8. The system further includes a display unit that displays a selection screen allowing the user to select the application of the saturated magnetic resonance signal. The magnetic resonance imaging apparatus according to claim 1.

9. The display unit displays on the selection screen whether or not the navigator has been selected for the aforementioned purpose. The magnetic resonance imaging apparatus according to claim 8.

10. As a pre-pulse, a saturated RF pulse is irradiated. The saturated magnetic resonance signal corresponding to the signal excited by the saturated RF pulse is spatially selectively read out. After irradiation with the saturation RF pulse, this acquisition is performed, which includes irradiation with an excitation RF pulse that is a different RF pulse from the saturation RF pulse. The collected data and the saturated magnetic resonance signal obtained through the aforementioned collection process are to be output. A magnetic resonance imaging method comprising the following features.

11. On the computer, As a pre-pulse, a saturated RF pulse is irradiated. The saturated magnetic resonance signal corresponding to the signal excited by the saturated RF pulse is spatially selectively read out. After irradiation with the saturation RF pulse, this acquisition is performed, which includes irradiation with an excitation RF pulse that is a different RF pulse from the saturation RF pulse. The collected data and the saturated magnetic resonance signal obtained through the aforementioned collection process are to be output. A magnetic resonance imaging program designed to achieve this.

Images