Magnetic resonance imaging apparatus and magnetic resonance imaging method

Abstract

To visualize a fluid.SOLUTION: A magnetic resonance imaging device of an embodiment includes a sequence control unit and a generation unit. The sequence control unit executes a pulse sequence for making collection after application of a tag pulse while dividing a k-space into a plurality of segments. The generation unit generates an image on the basis of the pulse sequence executed by the sequence control unit. The pulse sequence is a pulse sequence for repeatedly collecting the center of the k-space. The sequence control unit executes the pulse sequence while changing a range to which the tag pulse is applied for each of the plurality of segments.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] In magnetic resonance imaging, there is the 3D UTE (Ultrashort TE) imaging method, which has the following characteristics: high signal sensitivity due to a short TE, relatively strong against motion artifacts due to oversampling at the center of k-space, and little susceptibility.

[0003] Here, in order to selectively image blood vessels, it is desirable to suppress background signals (and fat signals). Therefore, by applying tag pulses using the Time-SLIP (Time-Spatial Labeling Inversion Pulse) method and combining 3D UTE acquisition with the Time-SLIP flow-in method, it is possible to depict the aorta, abdominal aorta, peripheral sites, etc. In this way, by combining 3D UTE imaging with the Time-SLIP method, it is possible to acquire three-dimensional k-space data while suppressing background signals.

[0004] In the case of blood vessels with relatively high flow velocity, it is possible to visualize blood by combining 3D UTE acquisition with the Time-SLIP method. However, it is difficult to visualize blood vessels with relatively low flow velocity, such as in the case of peripheral non-contrast magnetic resonance angiography (NC-MRA), by simply combining 3D UTE acquisition with the Time-SLIP method. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] US Patent Application Publication No. 2017 / 0219672 Summary of the Invention [Problem to be solved by the invention]

[0006] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to depict a fluid. 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]

[0007] A magnetic resonance imaging apparatus according to an embodiment includes a sequence controller and a generator. The sequence controller executes a pulse sequence for performing acquisition after applying a tag pulse while dividing a k-space into a plurality of segments. The generator generates an image based on the pulse sequence executed by the sequence control circuit.

[0008] The pulse sequence is a pulse sequence that repeatedly acquires the center of the k-space. The sequence control unit executes the pulse sequence while changing the range to which the tag pulse is applied for each of a plurality of segments. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a magnetic resonance imaging apparatus according to an embodiment. [Figure 2A] FIG. 2A is a diagram showing an example of acquisition performed by the magnetic resonance imaging apparatus according to the embodiment. [Figure 2B] FIG. 2B is a diagram showing an example of collection performed by the magnetic resonance imaging apparatus according to the embodiment. [Figure 2C] FIG. 2C is a diagram showing an example of acquisition performed by the magnetic resonance imaging apparatus according to the embodiment. [Figure 3A] FIG. 3A is a diagram illustrating a pulse sequence executed by the sequence control circuit 120 according to the embodiment. [Figure 3B] FIG. 3B is a diagram illustrating a pulse sequence executed by the sequence control circuit 120 according to the embodiment. [Figure 4] FIG. 4 is a flowchart illustrating the processing performed by the magnetic resonance imaging apparatus according to the first embodiment. [Figure 5A] FIG. 5A is a diagram illustrating the processing performed by the magnetic resonance imaging apparatus according to the first embodiment. [Figure 5B] FIG. 5B is a diagram illustrating the processing performed by the magnetic resonance imaging apparatus according to the first embodiment. [Figure 6] FIG. 6 is a diagram illustrating an area to which a tag pulse is applied in the first embodiment. [Figure 7A] FIG. 7A is a diagram illustrating an area to which a tag pulse is applied in the first embodiment. [Figure 7B] FIG. 7B is a diagram illustrating an area to which a tag pulse is applied in the first embodiment. [Figure 8A] FIG. 8A is a diagram illustrating an area to which a tag pulse is applied in the first embodiment. [Figure 8B] FIG. 8B is a diagram illustrating an area to which a tag pulse is applied in the first embodiment. [Figure 9] FIG. 9 is a diagram illustrating an example of a GUI (Graphical User Interface) related to the magnetic resonance imaging apparatus according to the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of a magnetic resonance imaging apparatus and a magnetic resonance imaging method will be described in detail with reference to the drawings. Here, common reference numerals are used to designate the same components, and duplicated descriptions will be omitted.

[0011] (First embodiment) FIG. 1 is a block diagram showing a magnetic resonance imaging apparatus 100 according to the first embodiment. As shown in FIG. 1, the magnetic resonance imaging apparatus 100 includes a static magnetic field magnet 101, a static magnetic field power supply (not shown), a gradient magnetic field coil 103, a gradient magnetic field power supply 104, a bed 105, a bed control circuit 106, a transmission coil 107, a transmission circuit 108, a reception coil 109, a reception circuit 110, a sequence control circuit 120 (sequence control unit), and an image processing device 130. Note that the magnetic resonance imaging apparatus 100 does not include a subject P (e.g., a human body). Also, the configuration shown in FIG. 1 is merely an example. For example, each unit in the sequence control circuit 120 and the image processing device 130 may be appropriately integrated or separated.

[0012] The static magnetic field magnet 101 is a magnet formed in a hollow, approximately cylindrical shape, and generates a static magnetic field in the internal space. The static magnetic field magnet 101 is, for example, a superconducting magnet, and is excited by receiving a current from a static magnetic field power supply. The static magnetic field power supply supplies a current to the static magnetic field magnet 101. As another example, the static magnetic field magnet 101 may be a permanent magnet, in which case the magnetic resonance imaging apparatus 100 does not need to include a static magnetic field power supply. Also, the static magnetic field power supply may be provided separately from the magnetic resonance imaging apparatus 100.

[0013] The gradient magnetic field coil 103 is a hollow coil formed in a 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 mutually orthogonal X, Y, and Z axes, and these three coils are individually supplied with current from a gradient magnetic field power supply 104 to generate gradient magnetic fields whose magnetic field strength changes along the X, Y, and Z axes. The gradient magnetic fields of the X, Y, and Z axes generated by the gradient magnetic field coil 103 are, for example, a slice gradient magnetic field Gs, a phase encoding gradient magnetic field Ge, and a readout gradient magnetic field Gr. The gradient magnetic field power supply 104 supplies current to the gradient magnetic field coil 103.

[0014] The bed 105 includes a top plate 105a on which the subject P is placed, and under the control of a bed control circuit 106, the top plate 105a is inserted into the cavity (imaging port) of the gradient magnetic field coil 103 with the subject P placed thereon. The bed 105 is usually installed so that its longitudinal direction is parallel to the central axis of the static magnetic field magnet 101. Under the control of the image processing device 130, the bed control circuit 106 drives the bed 105 to move the top plate 105a in the longitudinal direction and up and down directions.

[0015] 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 a transmission circuit 108. The transmission circuit 108 supplies the transmission coil 107 with an RF pulse corresponding to a Larmor frequency determined by the type of target atom and the magnetic field strength.

[0016] The receiving coil 109 is disposed inside the gradient magnetic field coil 103, and receives a magnetic resonance signal (hereinafter, referred to as an “MR signal” as necessary) emitted from the subject P due to the influence of a high frequency magnetic field. Upon receiving the magnetic resonance signal, the receiving coil 109 outputs the received magnetic resonance signal to the receiving circuit 110.

[0017] The above-mentioned transmitting coil 107 and receiving coil 109 are merely examples. The coils may be configured by combining one or more of a coil having only a transmitting function, a coil having only a receiving function, or a coil having a transmitting and receiving function.

[0018] The receiving circuit 110 detects a magnetic resonance signal output from the receiving coil 109, and generates magnetic resonance data based on the detected magnetic resonance signal. Specifically, the receiving circuit 110 generates magnetic resonance data by digitally converting the magnetic resonance signal output from the receiving coil 109. The receiving circuit 110 also transmits the generated magnetic resonance data to the sequence control circuit 120. The receiving circuit 110 may be provided on the side of a gantry device that includes the static magnetic field magnet 101, the gradient magnetic field coil 103, and the like.

[0019] The sequence control circuit 120 drives the gradient magnetic field power supply 104, the transmission circuit 108, and the reception circuit 110 based on sequence information transmitted from the image processing device 130 to perform imaging of the subject P. Here, the sequence information is information that defines a procedure for performing imaging. 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 strength of the RF pulse supplied by the transmission circuit 108 to the transmission coil 107 and the timing of applying the RF pulse, and the timing of the reception circuit 110 detecting a magnetic resonance signal. For example, the sequence control circuit 120 is an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array), or an electronic circuit such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). Details of the pulse sequence executed by the sequence control circuit 120 will be described later.

[0020] Furthermore, when the sequence control circuit 120 drives the gradient magnetic field power supply 104, the transmission circuit 108, and the reception circuit 110 to image the subject P, and receives magnetic resonance data from the reception circuit 110, the sequence control circuit 120 transfers the received magnetic resonance data to the image processing device 130.

[0021] The image processing device 130 performs overall control of the magnetic resonance imaging apparatus 100, generates images, etc. The image processing device 130 includes a memory 132, an input device 134, a display 135, and a processing circuit 150. The processing circuit 150 includes an interface function 131, a control function 133, and a generation function 136.

[0022] In the first embodiment, each processing function performed by the interface function 131, the control function 133, and the generation function 136 is stored in the memory 132 in the form of a program executable by a computer. The processing circuit 150 is a processor that reads out the program from the memory 132 and executes it to realize the function corresponding to each program. In other words, the processing circuit 150 in a state in which each program is read out has each function shown in the processing circuit 150 in FIG. 1. Note that in FIG. 1, the processing functions performed by the interface function 131, the control function 133, and the generation function 136 are described as being realized by a single processing circuit 150, but it is also possible to configure the processing circuit 150 by combining multiple independent processors, and to realize the functions by each processor executing a program. In other words, each of the above-mentioned functions may be configured as a program, and one processing circuit 150 may execute each program. As another example, a specific function may be implemented in a dedicated independent program execution circuit. Note that in FIG. 1, the interface function 131, the control function 133, and the generation function 136 are examples of a reception unit, a control unit, a generation unit, and an analysis unit, respectively. Moreover, the sequence control circuit 120 is an example of a sequence control unit.

[0023] The term "processor" used in the above description means a circuit such as a CPU (Central Processing Unit), a GPU (Graphical Processing Unit), 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)). The processor realizes functions by reading and executing a program stored in memory 132.

[0024] Also, instead of storing the program in the memory 132, the program may be directly built into the circuit of the processor. In this case, the processor realizes the function by reading and executing the program built into the circuit. The bed control circuit 106, the transmission circuit 108, the reception circuit 110, etc. are also similarly composed of electronic circuits such as the above-mentioned processor.

[0025] The processing circuitry 150 transmits sequence information to the sequence control circuit 120 through the interface function 131, and receives magnetic resonance data from the sequence control circuit 120. Furthermore, upon receiving the magnetic resonance data, the processing circuitry 150 having the interface function 131 stores the received magnetic resonance data in the memory 132.

[0026] The magnetic resonance data stored in the memory 132 is arranged in k-space by the control function 133. As a result, the memory 132 stores the k-space data.

[0027] The memory 132 stores magnetic resonance data received by the processing circuitry 150 having the interface function 131, k-space data arranged in the k-space by the processing circuitry 150 having the control function 133, image data generated by the processing circuitry 150 having the generation function 136, etc. For example, the memory 132 is a semiconductor memory element such as a RAM (Random Access Memory) or a flash memory, a hard disk, an optical disk, etc.

[0028] The input device 134 accepts various instructions and information input from an operator. The input device 134 is, for example, a pointing device such as a mouse or a trackball, a selection device such as a mode changeover switch, or an input device such as a keyboard. The display 135 displays, under the control of the processing circuit 150 having the control function 133, a GUI (Graphical User Interface) for accepting input of imaging conditions, an image generated by the processing circuit 150 having the generation function 136, and the like. The display 135 is, for example, a display device such as a liquid crystal display.

[0029] The processing circuitry 150 performs overall control of the magnetic resonance imaging apparatus 100 using the control function 133, and controls imaging, image generation, image display, and the like. For example, the processing circuitry 150 having the control function 133 accepts input of imaging conditions (imaging parameters, etc.) on a GUI, and generates sequence information according to the accepted imaging conditions. In addition, the processing circuitry 150 having the control function 133 transmits the generated sequence information to the sequence control circuit 120.

[0030] The processing circuitry 150 reads the k-space data from the memory 132 using the generation function 136, and performs reconstruction processing such as Fourier transform on the read k-space data to generate an image.

[0031] Next, a brief background of the embodiment will be described.

[0032] In magnetic resonance imaging, there is the 3D UTE (Ultrashort TE) imaging method, which has the following characteristics: high signal sensitivity due to a short TE, relatively strong against motion artifacts due to oversampling at the center of k-space, and little susceptibility.

[0033] Here, in order to selectively image blood vessels, it is desirable to suppress background signals (and fat signals). Therefore, by applying tag pulses using the Time-SLIP (Time-Spatial Labeling Inversion Pulse) method and combining 3D UTE acquisition with the Time-SLIP flow-in method, it is possible to depict the aorta, abdominal aorta, peripheral sites, etc. In this way, by combining 3D UTE imaging with the Time-SLIP method, it is possible to acquire three-dimensional k-space data while suppressing background signals.

[0034] Here, in the case of blood vessels with a relatively high flow velocity, it is possible to visualize the blood vessels by combining 3D UTE acquisition with the Time-SLIP method. However, it is difficult to visualize blood vessels with a relatively low flow velocity, such as when performing non-contrast magnetic resonance angiography (NC-MRA) of peripheral sites, by simply combining 3D UTE acquisition with the Time-SLIP method.

[0035] Therefore, the magnetic resonance imaging apparatus 100 according to the embodiment executes a pulse sequence in which, while dividing the k-space into a plurality of segments, a tagging pulse is applied, and then the center of the k-space is repeatedly collected. Here, the sequence control circuit 120 executes the pulse sequence while changing the range in which the tagging pulse is applied for each of the plurality of segments.

[0036] This makes it possible to effectively visualize blood vessels even in areas where blood flow is slow and visualization was difficult using conventional methods.

[0037] Such a configuration will be described with reference to FIGS. 2A to 9.

[0038] In the embodiment, the sequence control circuit 120 executes a pulse sequence that performs acquisition while repeatedly acquiring the center of k-space. Examples of these acquisitions that are performed while repeatedly acquiring the center of k-space are shown in FIG. 2A, FIG. 2B, and FIG. 2C. FIG. 2A, FIG. 2B, and FIG. 2C are diagrams showing examples of acquisitions performed by the magnetic resonance imaging apparatus 100 according to the embodiment. Specifically, FIG. 2A is an example of three-dimensional spherical acquisition, FIG. 2B is an example of spiral acquisition, and FIG. 2C is an example of stack-of-star acquisition. Note that, when performing three-dimensional UTE imaging, the sequence control circuit 120 performs acquisition using the three-dimensional spherical acquisition shown in FIG. 2A.

[0039] Fig. 2A shows the case of three-dimensional spherical acquisition. When performing three-dimensional UTE acquisition, the sequence control circuit 120 performs three-dimensional spherical acquisition as shown in Fig. 2A, and performs center-out acquisition in which acquisition is performed from the center of k-space toward the outside. Lines 10a, 10b, 10c, etc. show the acquisition of one line. In addition, the sequence control circuit 120 may perform additional acquisition by performing Cartesian sampling on the center part of k-space using, for example, a PETRA (Pointwise Encoding Time Reduction with Radial Acquisition) sequence or the like.

[0040] FIG. 2B shows the case of spiral acquisition. When performing spiral acquisition, the sequence control circuit 120 performs spiral acquisition within a two-dimensional plane, and calculates the distance between the two-dimensional plane and the perpendicular direction (k z Three-dimensional k-space data is acquired by sequentially acquiring k-space data at different positions in the x-axis direction (axis direction). Planes 40a, 40b, and 40c represent these two-dimensional stacks. The sequence control circuit 120 performs center-out acquisition from the center of k-space to the outside along the spiral 41 or 42, for example, in one two-dimensional plane.

[0041] FIG. 2C shows the case of stack-of-star acquisition. When stack-of-star acquisition is performed, the sequence control circuit 120 performs radial acquisition within a two-dimensional plane, and performs a vertical acquisition (k z Three-dimensional k-space data is acquired by sequentially acquiring k-space data at different positions (direction) of the scanning direction. Planes 43a, 43b, 43c, 43d, 43e, 43f, 43g, and 43h represent two-dimensional stacks of the data. The sequence control circuit 120 performs out-center-out acquisition within one two-dimensional plane, for example, along one line, starting from the outside of the k-space, passing through the center of the k-space, and returning to the outside of the k-space again. Lines 44a, 44b, 44c, 44d, 44e, etc. represent each of the lines.

[0042] In the embodiment, the sequence control circuit 120 executes a pulse sequence that combines acquisition performed by repeatedly acquiring data from the center of k-space, such as 3D UTE imaging, with a method of suppressing background signals by applying tag pulses, such as the Time-SLIP method. An overview of the pulse sequence executed by the sequence control circuit 120 will be described with reference to FIG. 3A.

[0043] First, the sequence control circuit 120 applies the tag pulse 11. Here, the sequence control circuit 120 applies the tag pulse while changing the range to which the tag pulse is applied for each of a number of segments, and these processes will be described later. Note that Fig. 3A explains the repetitive portion of the pulse sequence per application of a tag pulse, and the same pulse sequence is repeated every time a tag pulse is applied.

[0044] Next, the sequence control circuit 120 applies the venous suppression pulse 12 as necessary after applying the tag pulse 11. Thereafter, the sequence control circuit 120 executes an acquisition sequence 15 during a data acquisition time 16. As an example, the sequence control circuit 120 executes a 3D UTE sequence as the acquisition sequence 15 during the data acquisition time 16. As an example, the sequence control circuit 120 executes a pulse sequence in which a gradient echo is generated by applying a combination of a predetermined gradient magnetic field after applying a half pulse as the 3D UTE sequence.

[0045] In FIG. 3A, m is a fat suppression loop, and the sequence control circuit 120 repeats the acquisition sequence 15 for different k-space segments m times after applying the fat suppression pulse 13 and the spoiler 14. Also, n is a tag loop, that is, the sequence control circuit 120 executes the acquisition sequence 15 for n×m different k-space segments for one tag pulse 11. The sequence control circuit 120 executes these processes for multiple tag pulses. In this way, the sequence control circuit 120 executes a pulse sequence for performing acquisition by the acquisition sequence 15 after applying the tag pulse 11 while dividing the k-space into multiple segments.

[0046] When the position of the tag pulse is fixed and data is collected for all segments of the k-space, normal k-space data relating to the position of the tag pulse can be obtained.

[0047] Next, the influence of the application of the tag pulse on the signal value will be described with reference to FIG. 3B. In FIG. 3B, curve 17 represents the behavior of the longitudinal magnetization in the region other than the region to which the tag pulse 11 is applied, and curve 18 represents the behavior of the longitudinal magnetization of the spins that existed in the region to which the tag pulse 11 is applied at the time when the tag pulse 11 is applied. As shown by curve 17, the longitudinal magnetization of the spins that do not exist in the region to which the tag pulse 11 is applied at the time when the tag pulse 11 is applied does not change. On the other hand, as shown by curve 18, the longitudinal magnetization of the spins that existed in the region to which the tag pulse 11 is applied is inverted by the tag pulse 11 and then relaxed gradually. When the sequence control circuit 120 executes the acquisition sequence at null point 20, which is the point at which this longitudinal magnetization becomes zero, the signal of the longitudinal magnetization of the spins that existed in the region to which the tag pulse 11 is applied at the time when the tag pulse 11 is applied and that exist in the imaging region at the time when the acquisition is performed (data acquisition time 16) can be suppressed. In this way, a contrast is created between spins that have been subjected to the tagging pulse and those that have not, which can be utilized.

[0048] There are several variations in the pattern of tag pulses applied by the sequence control circuit 120. For example, there are various methods such as a flow-in method in which only a region-selective tag pulse is applied, a flow-out method in which a region-selective tag pulse and a region-non-selective pulse are applied, and a tag-on / tag-off method in which two images are captured, one with a region-selective tag pulse applied and the other without a region-selective tag pulse, and a difference process is performed between them.

[0049] FIG. 4 is a flowchart illustrating the processing performed by the magnetic resonance imaging apparatus according to the first embodiment.

[0050] First, in step S100, sequence control circuit 120 applies tag pulses while changing the range to which tag pulse 11 is applied for each of a plurality of segments in executing a pulse sequence.

[0051] As an example, the sequence control circuit 120 executes a pulse sequence while keeping the width of the region to which the tag pulse 11 is applied constant and varying the position at which the application of the tag pulse starts for each of a number of segments.

[0052] Such an example is shown in Fig. 5A. The sequence control circuit 120 applies the first tag pulse to region 1a, which is a rectangular region from start position 2a to end position 3a, the second tag pulse to region 1b, which is a rectangular region from start position 2b to end position 3b, the third tag pulse to region 1c, which is a rectangular region from start position 2c to end position 3c, the fourth tag pulse to region 1d, which is a rectangular region from start position 2d to end position 3d, and the fifth tag pulse to region 1e, which is a rectangular region from start position 2e to end position 3e. In this way, the sequence control circuit 120 applies the tag pulse while gradually translating the application region of the tag pulse for each segment in which collection is performed.

[0053] The reason why sequence control circuit 120 applies the tag pulse while changing the region to which the tag pulse is applied for each of a plurality of segments is as follows.

[0054] That is, the range in which the tag pulse is applied is usually moved after all k-space data has been collected. That is, by repeating the operation of applying a tag pulse in a certain area to collect data related to all segments of the k-space, and then changing the application area of ​​the tag pulse after collecting data related to all segments of the k-space data, information on blood flow can be obtained. However, since three-dimensional collection generally takes a long time for imaging, if the application area of ​​the tag pulse is changed after waiting for data of all segments of the k-space to be obtained, sufficient visualization can only be achieved when the blood flow is fast, and visualization is insufficient when the blood flow is slow. Therefore, in the magnetic resonance imaging apparatus 100 according to the embodiment, the area to which the tag pulse is applied is changed for each of a plurality of segments. As a result, even when the movement of the imaging target is slow, a sufficient inflow effect can be obtained for fluids with movement, such as arteries, veins, CSF, and pancreatic juice.

[0055] In addition, when the pulse sequence executed by the sequence control circuit 120 is, for example, a pulse sequence that collects k-space data by Cartesian sampling, it is expected that the error will increase if the area to which the tag pulse is applied is changed for each of multiple segments. However, in the embodiment, the pulse sequence executed by the sequence control circuit 120 is a type of pulse sequence that repeatedly collects the center of k-space, so that the error is unlikely to increase, and therefore such processing is justified.

[0056] Returning to FIG. 4, the sequence control circuit 120 applies the venous suppression pulse 12 in step S110.

[0057] Next, in step S120, the sequence control circuit 120 applies the fat suppression pulse 13, and then executes an acquisition sequence 15 such as a 3D UTE imaging sequence to acquire k-space data in a data acquisition time 16 including a null point 20. In the case of the pulse sequence shown in Fig. 3A, since the fat suppression loop is m and the tag loop is n, the execution of the acquisition sequence 15 is repeated m times per application of the fat suppression pulse 13, and the application of the fat suppression pulse 13 and the subsequent fat suppression loop are repeated n times per application of the tag pulse 11. In the case of Fig. 5A, the tag division number is "5", and the application of five tag pulses constitutes one set, and these are further repeated as multiple sets for different k-spaces.

[0058] When the application region of the tag pulse 11 is the region shown in FIG. 5A, the imaging region 21 in FIG. 5B is a typical imaging region.

[0059] Next, in step S130, the processing circuitry 150 causes the generating function 136 to generate a magnetic resonance image based on the pulse sequence executed by the sequence control circuitry 120 in steps S100-120.

[0060] In step S100, the sequence control circuit 120 executes the pulse sequence while changing the range to which the tag pulse 11 is applied in a direction parallel to the running direction of the blood vessel, thereby enabling efficient visualization of the blood flow. For example, if the running direction of the blood vessel 4 is as shown in Fig. 6, the sequence control circuit 120 may change the range to which the tag pulse 11 is applied to regions 3a, 3b, 3c, 3d, and 3e.

[0061] As another example of a variation of the method of changing the area to which the tag pulse is applied in step S100, the sequence control circuit 120 may execute a pulse sequence while changing the width of the area to which the tag pulse 11 is applied for each of a plurality of segments, while keeping the position at which the application of the tag pulse 11 ends (or starts) constant. For example, as shown in Fig. 7A, the sequence control circuit 120 may execute a pulse sequence while narrowing the width of the area to which the tag pulse 11 is applied for each of a plurality of segments, such as a first tag pulse 5a whose start position of the tag pulse 11 is position 50a, a second tag pulse 5b whose start position of the tag pulse 11 is position 50b, a third tag pulse 5c whose start position of the tag pulse 11 is position 50c, and a fourth tag pulse 5d whose start position of the tag pulse 11 is position 50d, while keeping the position 51 at which the application of the tag pulse 11 ends constant. By varying the area to which the tag pulse is applied in this way, the final image quality may be stabilized since the position where the application of the tag pulse 11 ends is fixed.

[0062] Also, when the blood vessel runs obliquely, the direction in which the region to which the tag pulse is applied is changed may be optimized with respect to the blood vessel running direction, and this is also the case with the manner in which the region to which the tag pulse is applied is changed. For example, when the blood vessel 4 runs in the direction shown in FIG. 7B, the sequence control circuit 120 executes a pulse sequence while changing the range to which the tag pulse 11 is applied in a direction parallel to the blood vessel running direction. For example, the sequence control circuit 120 executes a pulse sequence while narrowing the width of the region to which the tag pulse 11 is applied for each of a plurality of segments, such as a first tag pulse 6a whose start position of the tag pulse 11 is position 60a, a second tag pulse 6b whose start position of the tag pulse 11 is position 60b, a third tag pulse 6c whose start position of the tag pulse 11 is position 60c, and a fourth tag pulse 6d whose start position of the tag pulse 11 is position 60d, while keeping the position 61 at which the application of the tag pulse 11 ends constant.

[0063] As an application example, the sequence control circuit 120 may apply a tag pulse to multiple areas simultaneously, and further, the sequence control circuit 120 may change the area to which the tag pulse 11 is applied in a different manner for each of the multiple areas.

[0064] As an example, as shown in FIG. 8A, the sequence control circuit 120 applies a first tag pulse to the region 1a from the start position 2a to the end position 3a and the region 7a from the start position 8a to the end position 9a, a second tag pulse to the region 1b from the start position 2b to the end position 3b and the region 7b from the start position 8b to the end position 9b, a third tag pulse to the region 1c from the start position 2c to the end position 3c and the region 7c from the start position 8c to the end position 9c, and a fourth tag pulse to the region 1d from the start position 2d to the end position 3d and the region 7d from the start position 8d to the end position 9d. At this time, the sequence control circuit 120 makes the width of the change in the start position of the tag pulse different for each of the multiple regions to which the tag pulse is applied simultaneously. This allows the sequence control circuit 120 to optimize the imaging in accordance with the imaging target.

[0065] Similarly, as shown in FIG. 8B, while keeping positions 2e and 8e where application of tag pulse 11 ends constant, a pulse sequence may be executed by varying the width of the area where tag pulse 11 is applied for each of a plurality of segments, with a plurality of tag pulses whose start positions for tag pulse 11 are positions 3e and 9e respectively as first tag pulses 1i and 7e, a plurality of tag pulses whose start positions for tag pulse 11 are positions 3f and 9f respectively as second tag pulses 1f and 7f, a plurality of tag pulses whose start positions for tag pulse 11 are positions 3g and 9g respectively as third tag pulses 1g and 7g, and a plurality of tag pulses whose start positions for tag pulse 11 are positions 3h and 9h respectively as fourth tag pulses 1p and 7h.

[0066] 9 shows an example of a GUI according to the embodiment. The processing circuit 150 accepts, via the input device 134 that accepts input from the user, a selection of a simple sliding mode in which the position where the application of the tag pulse 11 starts is changed for each segment while keeping the width of the area where the tag pulse 11 is applied constant, or a variable slice thickness mode in which the width of the area where the tag pulse 11 is applied is changed for each segment while keeping the position where the application of the tag pulse 11 ends constant, via the control function 133 and the input device 134 that accepts input from the user.

[0067] When the user selects the simple sliding mode by clicking button 30, the processing circuit 150, through the input device, accepts, via the control function 133, changes to the tag division number using buttons 32a and 32b, changes to the initial tag slice position using buttons 32c and 32d, changes to the slice thickness using buttons 32e and 32f, and changes to the tag movement distance for each tag using buttons 32g and 32h, sets the tag pulse based on the accepted settings, and displays the setting results in the display area 1 of the display 135. For example, if the tag division number is "5", the initial tag slice position is "30 cm", the slice thickness is "30 cm", and the tag movement distance is "5 cm", the sequence control circuit 120 applies a first tag pulse to a position of "0 cm to 30 cm", a second tag pulse to a position of "-5 cm to 25 cm", a third tag pulse to a position of "-10 cm to 20 cm", a fourth tag pulse to a position of "-15 cm to 15 cm", and a fifth tag pulse to a position of "-20 cm to 10 cm".

[0068] In addition, when the user clicks button 31 to select the Variable Slice thickness mode, the processing circuit 150, through the input device, accepts, via the control function 133, a change in the number of tag divisions using buttons 33a and 33b, a change in the initial tag slice position using buttons 33c and 33d, a change in the initial slice thickness using buttons 33e and 33f, and a change in the reduction amount of slice thickness using buttons 33g and 33h, sets the tag pulse based on the accepted settings, and displays the setting results in the display area 5 of the display 135. For example, if the tag division number is "5", the initial tag slice position is "30 cm", the initial slice thickness is "30 cm", and the slice thickness reduction is "3 cm", the sequence control circuit 120 applies a first tag pulse to a position "0 cm to 30 cm", a second tag pulse to a position "0 cm to 27 cm", a third tag pulse to a position "0 cm to 24 cm", a fourth tag pulse to a position "0 cm to 21 cm", and a fifth tag pulse to a position "0 cm to 18 cm".

[0069] Furthermore, the processing circuit 150 accepts, via the input device 134, a change in the number of lines in the entire imaging using buttons 34a and 34b, and a change in the number of segments (or the number of lines) imaged in one entire set of tag pulses using buttons 34c and 34d using the control function 133. The processing circuit 150 also calculates the number of segments (or the number of lines) related to the imaging of one tag pulse based on the number of segments imaged in one entire set of tag pulses and the number of tag divisions using the control function 133, and displays the calculation result in the display area 35. For example, if the number of segments imaged in one entire set of tag pulses is 200 and the number of tag divisions is 5, the number of segments related to the imaging of one tag pulse is 200 / 5=40.

[0070] Furthermore, processing circuit 150 can accept a change in the tag pulse application area via input device 134 using control function 133. For example, processing circuit 150 can accept, via input device 134, a change in the tag pulse application area using buttons 36a, 36b, 36c, 36d, 36e, 36f, 36g, 36h, 37c, 37d, and 37e, an enlargement or reduction of the tag pulse application area using buttons 37a and 37b, and a setting of the tag pulse application direction (a rotation operation of the tag pulse application area) using buttons 37f, 37g, and 37h.

[0071] Such a GUI enables the sequence control circuit 120 to execute a pulse sequence while changing the range to which the tag pulse 11 is applied for each of a plurality of segments, based on an input received by the input device 134 from a user.

[0072] (program) Moreover, the instructions shown in the processing procedure shown in the above-mentioned embodiment can be executed based on a program, which is software. A general-purpose computer can store this program in advance and obtain the same effect as that of the magnetic resonance imaging apparatus 100 of the above-mentioned embodiment by reading this program. The instructions described in the above-mentioned embodiment are recorded as a program that can be executed by a computer on a magnetic disk (flexible disk, hard disk, etc.), an optical disk (CD-ROM, CD-R, CD-RW, DVD-ROM, DVD±R, DVD±RW, etc.), a semiconductor memory, or a recording medium similar thereto. The storage medium may be in any form as long as it is a storage medium that can be read by a computer or an embedded system. The computer can realize the same operation as the magnetic resonance imaging apparatus 100 of the above-mentioned embodiment by reading the program from the recording medium and executing the instructions described in the program based on this program with a CPU. Moreover, when the computer acquires or reads the program, it may acquire or read it through a network.

[0073] Also, an OS (Operating System) running on a computer based on instructions of a program installed in a computer or embedded system from a storage medium, a database management software, a MW (Middleware) such as a network, etc. may execute a part of each process for realizing the above-mentioned embodiments. Furthermore, the storage medium is not limited to a medium independent of a computer or embedded system, but also includes a storage medium that stores or temporarily stores a program downloaded from a LAN (Local Area Network), the Internet, etc. Also, the storage medium is not limited to one, and even when the process in the above-mentioned embodiments is executed from multiple media, it is included in the storage medium in the embodiments, and the configuration of the media may be any configuration.

[0074] The computer or embedded system in the embodiments is for executing each process in the above-mentioned embodiments based on a program stored in a storage medium, and may be any of a device consisting of a personal computer, a microcomputer, etc., a system in which multiple devices are connected to a network, etc. Furthermore, the computer in the embodiments is not limited to a personal computer, but also includes an arithmetic processing device and a microcomputer included in an information processing device, and is a general term for a device or apparatus that can realize the functions in the embodiments by a program.

[0075] According to the magnetic resonance imaging apparatus according to at least one of the embodiments described above, fluids such as blood can be effectively visualized.

[0076] According to at least one of the embodiments described above, a fluid can be visualized.

[0077] 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.

[0078] Regarding the above embodiment, the following supplementary notes are disclosed as one aspect and optional features of the invention.

[0079] (Appendix 1) A magnetic resonance imaging apparatus according to one aspect of the present invention includes a sequence controller and a generator. The sequence controller executes a pulse sequence for performing acquisition after application of a tagging pulse while dividing k-space into a plurality of segments. The generator generates an image based on the pulse sequence executed by the sequence controller. The pulse sequence is a pulse sequence for repeatedly acquiring data from the center of the k-space, and the sequence controller executes the pulse sequence while changing the range in which the tagging pulse is applied for each of the plurality of segments.

[0080] (Appendix 2) The sequence control unit may execute the pulse sequence while keeping the width of the area to which the tag pulse is applied constant and changing the position at which application of the tag pulse begins for each of the multiple segments.

[0081] (Appendix 3) The sequence control unit may execute the pulse sequence while changing the width of the area where the tag pulse is applied for each of the multiple segments, while keeping the position where the application of the tag pulse ends constant.

[0082] (Appendix 4) The sequence controller may perform 3D UTE (Ultrashort TE) acquisition as the acquisition.

[0083] (Appendix 5) The sequence control unit may perform Spiral acquisition or Stack Of Stars acquisition.

[0084] (Appendix 6) The sequence control unit may execute the pulse sequence while changing a range in which the tag pulse is applied in a direction parallel to a running direction of a blood vessel.

[0085] (Appendix 7) The sequence control unit may apply the tag pulse to a plurality of regions simultaneously, and change the region to which the tag pulse is applied in a different manner for each of the plurality of regions.

[0086] (Appendix 8) further comprising an input device for receiving an input from a user; The sequence control unit may execute the pulse sequence while changing a range to which the tag pulse is applied for each of the plurality of segments, based on an input received from the user by the input device.

[0087] (Appendix 9) A magnetic resonance imaging method according to one aspect of the present invention is a magnetic resonance imaging method executed by a magnetic resonance imaging apparatus, which executes a pulse sequence for performing acquisition after application of a tagging pulse while dividing a k-space into a plurality of segments, and generates an image based on the pulse sequence. The pulse sequence is a pulse sequence for repeatedly acquiring data at the center of the k-space, and is executed while changing the range in which the tagging pulse is applied for each of the plurality of segments. [Explanation of symbols]

[0088] 120 Sequence control circuit 130 Image Processing Device 131 Interface Functions 133 Control Functions 136 Generation function 150 Processing circuit

Claims

1. a sequence control unit that executes a pulse sequence for performing acquisition after applying a tag pulse while dividing the k-space into a plurality of segments; a generation unit that generates an image based on the pulse sequence executed by the sequence control unit, the pulse sequence is a pulse sequence that repeatedly acquires a center of the k-space, The sequence control unit executes the pulse sequence while changing a range to which the tag pulse is applied for each of the multiple segments of the k-space.

2. The magnetic resonance imaging apparatus of claim 1 , wherein the sequence control unit executes the pulse sequence while changing the position where application of the tag pulse begins for each of the multiple segments while keeping the width of the area to which the tag pulse is applied constant.

3. The magnetic resonance imaging apparatus of claim 1 , wherein the sequence control unit executes the pulse sequence while changing the width of the area to which the tag pulse is applied for each of the multiple segments while keeping the position where the application of the tag pulse ends constant.

4. The magnetic resonance imaging apparatus according to claim 1 , wherein the sequence control unit performs 3D UTE (Ultrashort TE) acquisition as the acquisition.

5. The magnetic resonance imaging apparatus according to claim 1 , wherein the sequence control unit performs Spiral acquisition or Stack Of Stars acquisition.

6. The magnetic resonance imaging apparatus according to claim 1 , wherein the sequence control unit executes the pulse sequence while changing a range in which the tag pulse is applied in a direction parallel to a running direction of a blood vessel.

7. The magnetic resonance imaging apparatus of claim 1 , wherein the sequence control unit applies the tag pulse to a plurality of regions simultaneously and changes the region to which the tag pulse is applied in a different manner for each of the plurality of regions.

8. further comprising an input device for receiving an input from a user; The magnetic resonance imaging apparatus according to claim 1 , wherein the sequence control unit executes the pulse sequence while changing a range to which the tag pulse is applied for each of the plurality of segments based on an input received from the user by the input device.

9. A magnetic resonance imaging method performed by a magnetic resonance imaging apparatus, comprising: A pulse sequence is executed in which a tag pulse is applied and then an acquisition is performed while dividing the k-space into a plurality of segments; generating an image based on the pulse sequence; the pulse sequence is a pulse sequence that repeatedly acquires a center of the k-space, A magnetic resonance imaging method, the method being performed while changing the range to which the tag pulse is applied for each of the multiple segments of the k-space.

Images