JP7263219B2 - Magnetic resonance imaging system - Google Patents

Description

The embodiments disclosed in the specification and drawings relate to a magnetic resonance imaging apparatus.

Conventionally, when a subject is imaged by a magnetic resonance imaging (MRI) apparatus, a positioning image including at least a portion of the subject is generated prior to generation of a diagnostic image, and the positioning image is There is known a technique for setting the imaging field of view (FOV) of a diagnostic image based on .

In this way, when setting the FOV of the diagnostic image based on the scouting image, it is important that the scouting image sufficiently includes the region of interest, which is the region to be imaged. Part or all of the region of interest may not be included in the generated positioning image depending on the condition of the subject placed in the . In that case, the operator normally performs an operation to adjust the FOV while looking at the positioning image that has already been picked up, and then picks up the positioning image again, which increases the burden on the operator.

JP 2017-202310 A JP 2015-213749 A JP 2019-76693 A

One of the problems to be solved by the embodiments disclosed in the specification and drawings is to reduce the operator's burden in setting the FOV. However, the problems to be solved by the embodiments disclosed in this specification and drawings are not limited to the above problems. A problem corresponding to each effect of each configuration shown in the embodiments described later can be positioned as another problem.

An MRI apparatus according to an embodiment generates a diagnostic image covering a region of interest in a subject, and includes a generation unit and a determination unit. The generator generates a first image including at least part of the subject prior to generating the diagnostic image. The determination unit determines whether or not the first image includes the entire region of interest. The generation unit generates the first image and the produces a second image with a different field of view.

FIG. 1 is a diagram showing a configuration example of an MRI apparatus according to the first embodiment. FIG. 2 is a flow chart showing the procedure of processing performed by each function of the MRI apparatus according to the first embodiment. FIG. 3 is a diagram illustrating an example of processing performed by each function of the MRI apparatus according to the first embodiment; FIG. 4 is a flow chart showing the procedure of processing performed by each function of the MRI apparatus according to the second embodiment. FIG. 5 is a diagram showing an example of processing performed by each function of the MRI apparatus according to the second embodiment.

Hereinafter, embodiments of the MRI apparatus according to the present application will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram showing a configuration example of an MRI apparatus according to the first embodiment.

For example, as shown in FIG. 1, the MRI apparatus 100 includes a static magnetic field magnet 1, a gradient magnetic field coil 2, a gradient magnetic field power supply 3, a whole body RF (Radio Frequency) coil 4, a local RF coil 5, a transmission circuit 6, a reception It comprises a circuit 7, an RF shield 8, a pedestal 9, a bed 10, an input interface 11, a display 12, a memory circuit 13, and processing circuits 14-17.

The static magnetic field magnet 1 generates a static magnetic field in an imaging space in which the subject S is arranged. Specifically, the static magnetic field magnet 1 is formed in a hollow, substantially cylindrical shape (including one having an elliptical cross-sectional shape perpendicular to the central axis), and an imaging space formed on the inner peripheral side thereof. to generate a static magnetic field. For example, the static magnetic field magnet 1 is a superconducting magnet, a permanent magnet, or the like. The superconducting magnet referred to here is composed of, for example, a container filled with a coolant such as liquid helium and a superconducting coil immersed in the container.

The gradient magnetic field coil 2 is arranged inside the static magnetic field magnet 1 and generates a gradient magnetic field in an imaging space where the subject S is arranged. Specifically, the gradient magnetic field coil 2 is formed in a hollow, substantially cylindrical shape (including one having an elliptical cross-sectional shape perpendicular to the central axis). It has an X-coil, a Y-coil and a Z-coil corresponding to each axis. The X coil, the Y coil, and the Z coil generate a gradient magnetic field that linearly changes along each axial direction in the imaging space based on the current supplied from the gradient magnetic field power supply 3 . Here, the Z axis is set along the magnetic flux of the static magnetic field generated by the static magnetic field magnet 1 . The X-axis is set along the horizontal direction perpendicular to the Z-axis, and the Y-axis is set along the vertical direction perpendicular to the Z-axis. As a result, the X-axis, Y-axis, and Z-axis constitute an apparatus coordinate system unique to the MRI apparatus 100 .

The gradient magnetic field power supply 3 supplies current to the gradient magnetic field coil 2 to generate a gradient magnetic field in the imaging space. Specifically, the gradient magnetic field power supply 3 supplies currents individually to the X coil, the Y coil, and the Z coil of the gradient magnetic field coil 2, so that the current is generated along each of the readout direction, the phase encoding direction, and the slice direction, which are orthogonal to each other. A linearly changing gradient magnetic field is generated in the imaging space. Hereinafter, the gradient magnetic field along the readout direction is called the readout gradient magnetic field, the gradient magnetic field along the phase encode direction is called the phase encode gradient magnetic field, and the gradient magnetic field along the slice direction is called the slice gradient magnetic field. .

Here, the readout gradient magnetic field, the phase encoding gradient magnetic field, and the slice gradient magnetic field are each superimposed on the static magnetic field generated by the static magnetic field magnet 1, so that the magnetic resonance signal generated from the subject S has spatial position information. to give Specifically, the readout gradient magnetic field changes the frequency of the magnetic resonance signal according to the position in the readout direction, thereby imparting positional information along the readout direction to the magnetic resonance signal. Also, the phase-encoding gradient magnetic field changes the phase of the magnetic resonance signal along the phase-encoding direction, thereby imparting positional information along the phase-encoding direction to the magnetic resonance signal. Also, the slice gradient magnetic field imparts positional information along the slice direction to the magnetic resonance signal. For example, the slice gradient magnetic field is used to determine the direction, thickness and number of slice regions when the imaging region is a slice region (2D imaging), and when the imaging region is a volume region (3D imaging) , are used to change the phase of the magnetic resonance signal according to the position in the slice direction. As a result, the axis along the readout direction, the axis along the phase encoding direction, and the axis along the slice direction form a logical coordinate system for defining the slice region or volume region to be imaged.

The whole-body RF coil 4 is arranged on the inner peripheral side of the gradient magnetic field coil 2, applies a high-frequency magnetic field to the subject S placed in the imaging space, and detects the magnetism generated from the subject S under the influence of the high-frequency magnetic field. Receive resonance signals. Specifically, the whole-body RF coil 4 is formed in a hollow, substantially cylindrical shape (including one having an elliptical cross-sectional shape perpendicular to the central axis), and the high-frequency pulse supplied from the transmission circuit 6 Based on the signal, a high-frequency magnetic field is applied to the subject S placed in the imaging space located on the inner circumference side. The whole-body RF coil 4 also receives magnetic resonance signals generated from the subject S under the influence of the high-frequency magnetic field, and outputs the received magnetic resonance signals to the receiving circuit 7 .

The local RF coil 5 receives magnetic resonance signals generated from the subject S. Specifically, a plurality of types of the local RF coil 5 are prepared so as to be applicable to each part of the subject S, and when the subject S is imaged, it is arranged near the surface of the part to be imaged. be done. The local RF coil 5 receives magnetic resonance signals generated from the subject S under the influence of the high-frequency magnetic field applied by the whole-body RF coil 4 and outputs the received magnetic resonance signals to the receiving circuit 7 . The local RF coil 5 may further have a function of applying a high-frequency magnetic field to the subject S. In that case, the local RF coil 5 is connected to the transmission circuit 6 and applies a high frequency magnetic field to the subject S based on the high frequency pulse signal supplied from the transmission circuit 6 . For example, the local RF coil 5 is a surface coil or a phased array coil configured by combining a plurality of surface coils as coil elements.

The transmission circuit 6 outputs to the whole-body RF coil 4 a high-frequency pulse signal corresponding to the Larmor frequency specific to the target nucleus placed in the static magnetic field. Specifically, the transmission circuit 6 includes a pulse generator, a high frequency generator, a modulator, and an amplifier. A pulse generator generates a waveform of a high frequency pulse signal. The high-frequency generator generates a high-frequency signal with a resonance frequency (Larmor frequency). The modulator generates a high frequency pulse signal by modulating the amplitude of the high frequency signal generated by the high frequency generator with the waveform generated by the pulse generator. The amplifier amplifies the high frequency pulse signal generated by the modulator and outputs it to the whole body RF coil 4 .

The receiving circuit 7 generates magnetic resonance (MR) data based on magnetic resonance signals output from the whole-body RF coil 4 or the local RF coil 5, and outputs the generated MR data to the processing circuit 15. . For example, the receiving circuit 7 includes a selector, a preamplifier, a phase detector, and an A/D (Analog/Digital) converter. The selector selectively inputs magnetic resonance signals output from the whole-body RF coil 4 or the local RF coil 5 . The preamplifier power-amplifies the magnetic resonance signal output from the selector. The phase detector detects the phase of the magnetic resonance signal output from the preamplifier. The A/D converter converts the analog signal output from the phase detector into a digital signal to generate MR data, and outputs the generated MR data to the processing circuit 15 . It should be noted that all the processing described here as being performed by the receiving circuit 7 does not necessarily have to be performed by the receiving circuit 7, and some processing ( For example, processing by an A/D converter, etc.) may be performed.

The RF shield 8 is arranged between the gradient magnetic field coil 2 and the whole-body RF coil 4 and shields the gradient magnetic field coil 2 from the high-frequency magnetic field generated by the whole-body RF coil 4 . Specifically, the RF shield 8 is formed in a hollow, substantially cylindrical shape (including one having an elliptical cross-sectional shape perpendicular to the central axis of the cylinder), and the inner peripheral side of the gradient magnetic field coil 2 It is arranged in the space so as to cover the outer peripheral surface of the whole-body RF coil 4 .

The pedestal 9 has a hollow bore 9a formed in a substantially cylindrical shape (including one having an elliptical cross-sectional shape perpendicular to the central axis), and includes a static magnetic field magnet 1, a gradient magnetic field coil 2, and a whole body RF. It houses the coil 4 and the RF shield 8 . Specifically, the frame 9 has the whole-body RF coil 4 arranged on the outer peripheral side of the bore 9a, the RF shield 8 arranged on the outer peripheral side of the whole-body RF coil 4, and the gradient magnetic field coil placed on the outer peripheral side of the RF shield 8. 2 are arranged, and the static magnetic field magnets 1 are arranged on the outer peripheral side of the gradient magnetic field coil 2, respectively. Here, the space inside the bore 9a of the gantry 9 serves as an imaging space in which the subject S is placed during imaging.

The bed 10 has a tabletop 10a on which the subject S is placed, and a moving mechanism for moving the tabletop 10a vertically and horizontally. Here, the vertical direction is the vertical direction, and the horizontal direction is the direction along the central axis of the static magnetic field magnet 1 . With such a configuration, the bed 10 can change the height of the top plate 10a by moving the top plate 10a in the vertical direction. Further, by horizontally moving the top plate 10a of the bed 10, the position of the top plate 10a can be changed between the space outside the pedestal 9 and the imaging space within the bore 9a of the pedestal 9. ing.

Here, an example in which the MRI apparatus 100 has a so-called tunnel structure in which the static magnetic field magnet 1, the gradient magnetic field coil 2, and the whole-body RF coil 4 are each formed in a substantially cylindrical shape will be described. Embodiments are not limited to this. For example, the MRI apparatus 100 has a so-called open structure in which a pair of static magnetic field magnets, a pair of gradient magnetic field coils, and a pair of RF coils are arranged to face each other across an imaging space in which the subject S is arranged. You may have In such an open structure, the space sandwiched by a pair of static magnetic field magnets, a pair of gradient magnetic field coils and a pair of RF coils corresponds to the bore in the tunnel structure.

The input interface 11 receives input operations of various instructions and various information from the operator. Specifically, the input interface 11 is connected to the processing circuit 17 , converts an input operation received from the operator into an electric signal, and outputs the electric signal to the processing circuit 17 . For example, the input interface 11 includes a trackball, a switch button, a mouse, a keyboard, a touch pad for performing input operations by touching the operation surface, a display for setting imaging conditions and a region of interest (ROI), and the like. It is realized by a touch screen in which a screen and a touch pad are integrated, a non-contact input circuit using an optical sensor, an audio input circuit, and the like. In this specification, the input interface 11 is not limited to those including physical operation parts such as a mouse and a keyboard. For example, the input interface 11 also includes an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device provided separately from the device and outputs the electrical signal to the control circuit.

The display 12 displays various information and various images. Specifically, the display 12 is connected to the processing circuit 17, converts various information and image data sent from the processing circuit 17 into electrical signals for display, and outputs the electrical signals. For example, the display 12 is implemented by a liquid crystal monitor, CRT monitor, touch panel, or the like.

The storage circuit 13 stores various data and various programs. Specifically, the storage circuit 13 is connected to the processing circuits 14 to 17 and stores various data and various programs input/output by each processing circuit. For example, the storage circuit 13 is implemented by a semiconductor memory device such as a RAM (Random Access Memory), a flash memory, a hard disk, an optical disk, or the like.

The processing circuit 14 has a bed control function 14a. The bed control function 14 a controls the operation of the bed 10 by outputting control electric signals to the bed 10 . For example, the bed control function 14a accepts an instruction from the operator to move the tabletop 10a vertically or horizontally via the input interface 11 or an operation panel provided on the gantry 9, and moves the tabletop according to the received instruction. The movement mechanism of the top plate 10a of the bed 10 is operated so as to move the bed 10a. For example, the bed control function 14a moves the tabletop 10a on which the subject S is placed to the imaging space within the bore 9a of the gantry 9 when the subject S is imaged.

The processing circuit 15 has an acquisition function 15a. The acquisition function 15a acquires MR data of the subject S by executing various pulse sequences. Specifically, the acquisition function 15a executes various pulse sequences by driving the gradient magnetic field power supply 3, the transmission circuit 6, and the reception circuit 7 according to the sequence execution data output from the processing circuit 17. FIG. Here, the sequence execution data is data representing a pulse sequence, and includes the timing and strength of the current supplied by the gradient magnetic field power supply 3 to the gradient magnetic field coil 2, and the high frequency This information defines the timing of supplying the pulse signal, the strength of the high-frequency pulse to be supplied, the timing of sampling the magnetic resonance signal by the receiving circuit 7, and the like. Then, the acquisition function 15a receives the MR data output from the receiving circuit 7 as a result of executing the pulse sequence, and causes the storage circuit 13 to store the MR data. At this time, the MR data stored in the storage circuit 13 has position information along each direction of the readout direction, the phase-out direction, and the slice direction by the readout gradient magnetic field, the phase-encoding gradient magnetic field, and the slice gradient magnetic field. By being assigned, it is stored as k-space data representing a two-dimensional or three-dimensional k-space.

The processing circuit 16 has a generating function 16a. The generating function 16a generates various images based on the MR data collected by the collecting function 15a. Specifically, the generating function 16a reads the MR data collected by the collecting function 15a from the storage circuit 13, and performs reconstruction processing such as Fourier transform on the read MR data to obtain a two-dimensional or three-dimensional image. to generate Then, the generation function 16a causes the memory circuit 13 to store the generated image.

The processing circuit 17 has an imaging control function 17a, a determination function 17b, and an estimation function 17c. The imaging control function 17 a performs overall control of the MRI apparatus 100 by controlling each component of the MRI apparatus 100 . Specifically, the imaging control function 17a displays on the display 12 a GUI (Graphical User Interface) for receiving input operations of various instructions and various information from the operator, and inputs input operations received via the input interface 11. , each component of the MRI apparatus 100 is controlled. For example, the imaging control function 17a generates sequence execution data based on imaging conditions input by the operator, and outputs the generated sequence execution data to the processing circuit 15 to acquire MR data. Also, for example, the imaging control function 17a controls the processing circuit 16 to reconstruct an image based on the MR data acquired by the acquisition function 15a. Further, for example, the imaging control function 17a reads an image stored in the storage circuit 13 and displays the read image on the display 12 in response to a request from the operator. Note that the determination function 17b and the estimation function 17c will be described later in detail.

Here, for example, each of the processing circuits 14 to 17 is implemented by a processor. In this case, the processing functions of each processing circuit are stored in the storage circuit 13 in the form of a computer-executable program, for example. Each processing circuit reads and executes each program from the storage circuit 13, thereby realizing a processing function corresponding to each program. In other words, each processing circuit with each program read has each function shown in each processing circuit in FIG.

Also, here, each processing circuit has been described as being realized by a single processor, but the embodiments are not limited to this, and each processing circuit is configured by combining a plurality of independent processors, and each processor is a program. Each processing function may be realized by executing Also, the processing functions of each processing circuit may be appropriately distributed or integrated in a single or a plurality of processing circuits. In the example shown in FIG. 1, the single memory circuit 13 stores programs corresponding to each processing function. A configuration in which the corresponding program is read out from the circuit may be used.

The configuration example of the MRI apparatus 100 according to the present embodiment has been described above. With such a configuration, the MRI apparatus 100 according to this embodiment has a function of generating a diagnostic image covering the region of interest in the subject S. FIG. Here, the region of interest is a region containing anatomical features that are minimally required for a diagnostic image.

Specifically, the MRI apparatus 100 generates a positioning image (also called a locator image or a scout image) including at least a portion of the subject S prior to generating a diagnostic image, and diagnoses based on the positioning image. Sets the FOV of the image. Then, the MRI apparatus 100 acquires MR data in the set FOV and generates a diagnostic image based on the MR data.

In this way, when setting the FOV of the diagnostic image based on the scouting image, it is important that the scouting image sufficiently includes the region of interest, which is the region to be imaged. Depending on the state of the subject S placed above, the generated positioning image may not include part or all of the region of interest.

Generally, the scouting image is captured with an FOV initially set in advance so as to include the center of the magnetic field. If the local RF coil 5 or the like is placed between the subject S, the subject S will deviate from the position assumed in advance, and as a result, the positioning image will not sufficiently include the region of interest. can be. In that case, the operator normally performs an operation to adjust the FOV while looking at the positioning image that has already been picked up, and then picks up the positioning image again, which increases the burden on the operator.

For this reason, the present embodiment is configured to reduce the burden on the operator in setting the FOV.

Specifically, the generating function 16a of the processing circuit 16 generates a first scouting image including at least part of the subject S prior to generating the diagnostic image. Also, the determination function 17b of the processing circuit 17 determines whether or not the entire region of interest is included in the first positioning image generated by the generation function 16a. Then, when the determination function 17b determines that at least part of the region of interest is not included in the first positioning image, the generation function 16a generates the first positioning image and produces a second positioning image with a different FOV.

Here, in the present embodiment, when the determination function 17b determines that the first positioning image does not include at least part of the region of interest, the estimation function 17c of the processing circuit 17 determines that the first positioning image Estimate the position of the region of interest based on Then, the generation function 16a generates, as a second positioning image, an FOV image set to include the entire region of interest based on the position of the region of interest estimated by the estimation function 17c.

Note that the generation function 16a is an example of a generation unit. Also, the determination function 17b is an example of a determination unit. Also, the estimation function 17c is an example of an estimation unit. Also, the first positioning image is an example of the first image, and the second positioning image is an example of the second image.

According to such a configuration, when the initially captured positioning image does not include part or all of the region of interest, the optimum FOV for subsequently re-capturing the positioning image is automatically set. Become so. As a result, in this embodiment, it is possible to reduce the burden on the operator for setting the FOV.

Note that the FOV here means the area in which data used for image generation is collected. For example, in order to prevent aliasing artifacts, oversampling is performed to collect data in a wider range than the area to be imaged. In some cases, non-imaged areas shall also be included.

Processing performed by each function described above will be described in more detail below.

FIG. 2 is a flow chart showing the procedure of processing performed by each function of the MRI apparatus 100 according to the first embodiment. FIG. 3 is a diagram showing an example of processing performed by each function of the MRI apparatus 100 according to the first embodiment.

For example, as shown in FIG. 2, in the present embodiment, the imaging control function 17a receives an instruction to start imaging from the operator after the subject S is placed in the imaging space within the bore 9a of the gantry 9. If so (step S101, Yes), the following processing is started.

First, the acquisition function 15a acquires MR data in a positioning image FOV that is initialized to include the magnetic field center (step S102). Then, the generation function 16a generates a first positioning image including at least part of the subject S based on the MR data acquired by the acquisition function 15a (step S103).

For example, as shown in (a) of FIG. 3, the generation function 16a generates a first positioning image including at least part of the subject S based on MR data acquired in the FOV 31 that has been initialized. Generate.

After that, the determination function 17b determines whether or not the entire region of interest is included in the first positioning image generated by the generation function 16a (step S104).

At this time, for example, the determination function 17b detects the outer shape of the region of interest from the first positioning image, and if at least part of the region of interest is missing, the first positioning image has at least part of the region of interest. Determine that it is not included. For example, the determination function 17b generates a histogram of brightness values included in the first positioning image, and determines that at least part of the region of interest is not included when there is a location where the brightness value changes extremely. do.

Alternatively, for example, the determination function 17b detects an anatomical feature from the first positioning image, and if the detected anatomical feature point indicates a position different from the region of interest, the first positioning It may be determined that the image does not include at least part of the region of interest. Here, as a method for detecting anatomical feature points from the first positioning image, various known image processing techniques can be used.

Then, when the determining function 17b determines that at least part of the region of interest is not included in the first positioning image (step S104, No), the estimating function 17c performs , the position of the region of interest is estimated (step S105).

At this time, for example, the estimation function 17c estimates the position of the region of interest based on the anatomical feature points detected from the first positioning image.

Alternatively, for example, the estimation function 17c may estimate the position of the region of interest by performing pattern matching between the first positioning image and the model image. Here, the model image is, for example, an image obtained by picking up a standard subject, an image simulating the internal structure of the standard subject, or the like.

Alternatively, for example, the estimation function 17c inputs the first positioning image to a trained model that outputs the position of the region of interest based on an image that does not include at least part of the region of interest, A location of the region of interest may be estimated. In this case, for example, the trained model is created by machine learning such as deep learning. In addition to the image, the input to the trained model may further include information such as the height, weight, age, and sex of the subject S, and information such as the part of the imaging target.

Thereafter, based on the position of the region of interest estimated by the estimation function 17c, the imaging control function 17a resets the FOV of the positioning image so as to include the entire region of interest (step S106).

For example, as shown in (b) of FIG. 3, the imaging control function 17a moves the initially set FOV 31 to a position that includes the entire region of interest R based on the position of the region of interest R, and performs a new operation. The FOV of the positioning image is reset by setting the FOV32.

At this time, for example, the imaging control function 17a acquires MR data when the reset position of the FOV is a position where MR data cannot be acquired at the position of the subject S at that time. The top plate 10a on which the subject S is placed may be moved to a position where it is possible to do so.

Alternatively, for example, if the imaging control function 17a cannot acquire MR data with the reset FOV even if the tabletop 10a is moved within a possible range, the imaging control function 17a informs the operator, administrator, etc. You may notify us. For example, the imaging control function 17a, via the display 12, HIS (Hospital Information System) or the like connected to the MRI apparatus 100 via a network, indicates that it is impossible to acquire MR data with the reset FOV. to notify you.

After that, the acquisition function 15a acquires MR data with the FOV of the positioning image reset by the imaging control function 17a (step S107). Then, the generation function 16a generates a second positioning image including the entire region of interest based on the MR data acquired by the acquisition function 15a (step S108).

For example, as shown in FIG. 3(b), the generation function 16a generates a second positioning image including the entire region of interest R based on MR data acquired with the newly set FOV 32.

After that, the imaging control function 17a sets the FOV of the diagnostic image based on the second positioning image generated by the generating function 16a (step S109).

For example, as shown in (c) of FIG. 3, the imaging control function 17a sets the FOV 33 of the diagnostic image so as to cover the region of interest R based on the second positioning image.

At this time, for example, the imaging control function 17a detects anatomical feature points related to the region of interest from the second positioning image, and sets an FOV covering the region of interest based on the detected anatomical feature points. automatically sets the FOV of the diagnostic image.

Alternatively, for example, the imaging control function 17a displays a second positioning image on the display 12, and receives an operation from the operator to set an FOV that covers the region of interest on the displayed positioning image, thereby obtaining a diagnostic image. FOV may be set.

If the determination function 17b determines that the entire region of interest is included in the first positioning image (step S104, Yes), the imaging control function 17a, based on the first positioning image, The FOV of the diagnostic image is set (step S109).

After that, the acquisition function 15a acquires MR data in the FOV of the diagnostic image set by the imaging control function 17a (step S110). Then, the generation function 16a generates a diagnostic image covering the region of interest based on the MR data acquired by the acquisition function 15a (step S111).

Here, for example, the processing of steps S101, S106, and S109 in the above-described processing procedure is realized by the processing circuit 17 reading a program corresponding to the imaging control function 17a from the storage circuit 13 and executing it. be. Further, the processes of steps S102, S107 and S110 are realized by, for example, the processing circuit 15 reading a program corresponding to the collection function 15a from the storage circuit 13 and executing it. Further, the processes of steps S103, S108, and S111 are realized by, for example, the processing circuit 16 reading a program corresponding to the generation function 16a from the storage circuit 13 and executing it. Further, the process of step S104 is realized by, for example, the processing circuit 17 reading out a program corresponding to the determination function 17b from the storage circuit 13 and executing the program. Further, the process of step S105 is realized, for example, by the processing circuit 17 reading a program corresponding to the estimation function 17c from the storage circuit 13 and executing the program.

As described above, in the first embodiment, when the initially captured positioning image does not include part or all of the region of interest, the optimal FOV for re-imaging the positioning image is automatically determined. will be set.

Therefore, according to the first embodiment, it is possible to reduce the operator's burden of setting the FOV of the positioning image when the positioning image is re-captured.

Further, according to the first embodiment, the operability of the MRI apparatus 100 can be improved by automating the setting of the FOV of the positioning image.

Further, in recent years, studies have been made on automating part or all of the inspection using AI (Artificial Intelligence) or the like. By automatically setting the FOV of the image as well, it becomes possible to automatically capture the localization image and the diagnostic image in a single examination.

(Second embodiment)
In addition, in the above-described first embodiment, an example in which a diagnostic image is captured for one region of interest has been described, but embodiments of the technology disclosed by the present application are not limited to this. For example, the FOV setting method disclosed in the present application can also be applied to a case where the table 10a on which the subject S is placed is moved to capture diagnostic images of a plurality of regions of interest.

That is, in the first embodiment, when imaging one region of interest, an example was described in which an FOV for re-imaging a positioning image was set based on the positioning image that was first captured. By a similar method, when imaging a plurality of regions of interest by moving the tabletop 10a, the FOV of the positioning image of the next region of interest can be set based on the positioning image of one region of interest.

Such an example will be described below as a second embodiment. In addition, below, the second embodiment will be described with a focus on the points that are different from the first embodiment, and detailed descriptions of the contents common to the first embodiment will be omitted.

Specifically, the MRI apparatus 100 according to the present embodiment moves the top board 10a on which the subject S is placed, and generates a first diagnostic image covering a first region of interest in the subject S, and generating a second diagnostic image covering a second region of interest that is different from the first region of interest.

Then, in this embodiment, the generation function 16a of the processing circuit 16 generates the first scouting image of the FOV set to include the entire first region of interest prior to the generation of the first diagnostic image. Generate. Also, the determination function 17b of the processing circuitry 17 determines whether or not the entire second region of interest is included in the first positioning image generated by the generation function 16a. Then, when the determining function 17b determines that at least part of the second region of interest is not included in the first positioning image, the generating function 16a generates the top plate prior to the second diagnostic image. 10a is moved to generate a second positioning image with a FOV set to include all of the second region of interest.

Here, in the present embodiment, the estimation function 17c of the processing circuit 17 determines that the first positioning image does not include at least part of the second region of interest by the determination function 17b. estimating the position of the second region of interest based on the localization image of . Then, the generation function 16a generates, as a second positioning image, an FOV image set to include the entire second region of interest based on the position of the second region of interest estimated by the estimation function 17c. Generate.

As described above, the MRI apparatus 100 according to the present embodiment generates a scouting image for one region of interest, captures a diagnostic image with an FOV set based on the scouting image, and then captures the next region of interest. By repeating the processing procedure for setting the FOV of the positioning image in (1) while moving the table 10a on which the subject S is placed, diagnostic images are generated for each of the plurality of regions of interest.

In this way, as an example of imaging diagnostic images of a plurality of regions of interest by moving the top plate 10a on which the subject S is placed, imaging of the lower extremities, DWIBS (Diffusion-weighted Whole Body Imaging with background suppression), etc.

Processing performed by each function described above will be described in more detail below.

FIG. 4 is a flow chart showing the procedure of processing performed by each function of the MRI apparatus 100 according to the second embodiment. FIG. 5 is a diagram showing an example of processing performed by each function of the MRI apparatus 100 according to the second embodiment. Note that the example shown in FIG. 5 shows an example in which a plurality of regions of interest included in the lower limbs of the subject S are imaged by moving the top board 10a on which the subject S is placed.

For example, as shown in FIG. 4, in the present embodiment, the imaging control function 17a receives an instruction to start imaging from the operator after the subject S is placed in the imaging space within the bore 9a of the gantry 9. If so (step S201, Yes), the following processing is started.

First, the acquisition function 15a acquires MR data in a positioning image FOV set to include the entire first region of interest (step S202).

At this time, for example, the acquisition function 15a acquires MR data with an FOV that is preset in advance so as to include the magnetic field center, and at least a portion of the first region of interest on the localization image generated based on the MR data. If was not included, acquire MR data with the FOV reconfigured to include all of the first region of interest by the method described in the first embodiment.

Then, the generating function 16a generates a first scouting image based on the MR data collected by the collecting function 15a (step S203).

For example, as shown in (a) of FIG. 5, the generation function 16a generates MR data based on the MR data acquired in the FOV 51 set to include the entire first region of interest R1 including the pelvis of the subject S. to generate a first positioning image.

After that, the imaging control function 17a sets the FOV of the diagnostic image based on the first positioning image generated by the generating function 16a (step S204).

At this time, for example, the imaging control function 17a detects anatomical feature points related to the first region of interest from the first positioning image, and covers the first region of interest based on the detected anatomical feature points. By setting the FOV to be used, the FOV of the diagnostic image is automatically set.

Alternatively, for example, the imaging control function 17a displays the first positioning image on the display 12, and receives an operation from the operator to set the FOV that covers the first region of interest on the displayed first positioning image. Thus, the FOV of the diagnostic image may be set.

After that, the acquisition function 15a acquires MR data in the FOV of the diagnostic image set by the imaging control function 17a (step S205).

Then, the generation function 16a generates a first diagnostic image covering the first region of interest based on the MR data acquired by the acquisition function 15a (step S206).

After that, the determination function 17b determines whether or not the first positioning image generated by the generation function 16a includes the entire next region of interest (step S207).

At this time, for example, the determination function 17b detects anatomical feature points from the first positioning image, and the detected anatomical feature points do not include all the anatomical features of the next region of interest. If so, it is determined that at least part of the next region of interest is not included.

Alternatively, for example, the determination function 17b performs pattern matching between the first positioning image and a model image including at least the first region of interest and the next region of interest, so that the entire next region of interest is included. It may be determined whether or not

Then, when the determining function 17b determines that at least part of the next region of interest is not included in the first positioning image (step S207, No), the estimating function 17c determines that the first positioning image Based on this, the position of the next region of interest is estimated (step S208).

At this time, for example, the estimation function 17c estimates the position of the next region of interest based on the anatomical feature points detected from the first positioning image, as in the first embodiment. Alternatively, for example, the estimation function 17c may estimate the position of the next region of interest from the first positioning image using a model image or a learned model, as in the first embodiment.

For example, as shown in (a) of FIG. 5, the estimation function 17c detects the running direction of the joints and bones detected from the first region of interest R1 including the pelvis, and the knees of the subject S are detected. Estimate the position of the next region of interest R2.

Thereafter, based on the position of the next region of interest estimated by the estimation function 17c, the imaging control function 17a sets the FOV of the positioning image so as to include the entire next region of interest (step S209).

For example, as shown in FIG. 5(b), the imaging control function 17a sets a new FOV 52 to include the entire region of interest R2 based on the position of the region of interest R2 including the knee.

Then, the imaging control function 17a controls the bed control function 14a to move the table 10a on which the subject S is placed to a position where MR data can be acquired with the set FOV. (Step S210).

After that, the acquisition function 15a acquires MR data in the FOV of the positioning image set by the imaging control function 17a (step S211). Then, the generating function 16a generates a positioning image based on the MR data collected by the collecting function 15a (step S212).

For example, as shown in (b) of FIG. 5, the generation function 16a generates a positioning image including the entire region of interest R2 including the knee based on the MR data acquired with the newly set FOV 52. .

After that, the imaging control function 17a sets the FOV of the diagnostic image based on the positioning image generated by the generating function 16a (step S213).

At this time, for example, the imaging control function 17a detects anatomical feature points related to the region of interest from the positioning image by image processing, and sets an FOV covering the region of interest based on the detected anatomical feature points. automatically sets the FOV of the diagnostic image.

Alternatively, for example, the imaging control function 17a displays a positioning image on the display 12, and receives an operation from the operator to set an FOV that covers the region of interest on the displayed positioning image, thereby setting the FOV of the diagnostic image. You may

Note that when the determination function 17b determines that the first positioning image includes the entire next region of interest (step S207, Yes), the imaging control function 17a determines the to set the FOV of the diagnostic image (step S213).

After that, the acquisition function 15a acquires MR data in the FOV of the diagnostic image set by the imaging control function 17a (step S214). Then, the generation function 16a generates a diagnostic image covering the region of interest based on the MR data acquired by the acquisition function 15a (step S215).

Thereafter, the imaging control function 17a determines whether or not diagnostic images have been generated for all regions of interest (step S216), and if generated (step S216, Yes), the process ends.

On the other hand, if there remains a region of interest for which no diagnostic image has been generated (step S216, No), the determination function 17b determines whether or not the positioning image generated immediately before contains the entire next region of interest. (return to step S207). After that, the first positioning image is replaced with the positioning image that was generated immediately before, and the processes after step S207 described above are executed. As a result, the processes of steps S207 to S216 described above are repeatedly executed until diagnostic images are generated for all regions of interest.

Here, for example, the processing of steps S201, S204, S209, S210, S213, and S216 in the above-described processing procedure is performed by the processing circuit 17 reading a program corresponding to the imaging control function 17a from the storage circuit 13. It is realized by executing Further, the processes of steps S202, S205, S211 and S214 are realized by, for example, the processing circuit 15 reading a program corresponding to the collection function 15a from the storage circuit 13 and executing it. Further, the processes of steps S203, S206, S212 and S215 are realized by, for example, the processing circuit 16 reading a program corresponding to the generation function 16a from the storage circuit 13 and executing it. Further, the process of step S207 is realized by, for example, the processing circuit 17 reading a program corresponding to the determination function 17b from the storage circuit 13 and executing the program. Further, the process of step S208 is realized by, for example, the processing circuit 17 reading out a program corresponding to the estimation function 17c from the storage circuit 13 and executing the program.

As described above, in the second embodiment, when the positioning image captured first does not include part or all of the next region of interest, the positioning image of the next region of interest is captured. The optimal FOV will be set automatically.

Therefore, according to the second embodiment, when the top board 10a on which the subject S is placed is moved and diagnostic images of a plurality of regions of interest are captured, the FOV of the positioning image for each region of interest is set. The operator's burden can be reduced.

In each of the above-described embodiments, an example in which the FOV setting method disclosed in the present application is applied to setting the FOV of the positioning image has been described, but the embodiments are not limited to this. For example, the FOV setting method disclosed in the present application can be similarly applied to setting the FOV of diagnostic images. That is, in the same manner as in the example targeting the FOV of the positioning image described in each of the above embodiments, when imaging one region of interest with the FOV of the diagnostic image as the target, based on the first captured diagnostic image Subsequently, when setting the FOV for recapturing a diagnostic image, or when imaging a plurality of regions of interest by moving the top plate 10a, the next region of interest is captured based on the diagnostic image of one region of interest. It is possible to set the FOV of the diagnostic image of the region.

Further, in each of the above-described embodiments, the determining unit and the estimating unit in this specification are implemented by the determining function 17b and the estimating function 17c of the processing circuit 17, respectively, and the generating unit is implemented by the generating function 16a of the processing circuit 16. Although an example has been described, embodiments are not so limited. For example, the determining unit, the estimating unit, and the generating unit in this specification are realized by the functions described in the embodiments, and the same functions are realized by hardware only, software only, or a mixture of hardware and software. It does not matter if it is realized.

In addition, the term "processor" used in the above description is, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or an application specific integrated circuit (ASIC), a programmable logic device (eg, Simple Programmable Logic Device (SPLD), Complex Programmable Logic Device (CPLD), and Field Programmable Gate Array (FPGA)). When the processor is, for example, a CPU, the processor implements its functions by reading and executing a program stored in a memory circuit. On the other hand, if the processor is, for example, an ASIC, then instead of storing the program in a memory circuit, the relevant functions are built directly into the circuitry of the processor as logic circuits. Note that each processor of the present embodiment is not limited to being configured as a single circuit for each processor, and may be configured as one processor by combining a plurality of independent circuits to realize its function. good. Furthermore, a plurality of components in FIG. 1 may be integrated into one processor to realize its functions.

Here, the program executed by the processor is provided by being stored in a non-transitory storage medium, for example. For example, the program is preinstalled in a storage circuit such as a ROM (Read Only Memory) and provided. Alternatively, for example, the program can be stored on a CD (Compact Disk)-ROM, FD (Flexible Disk), CD-R (Recordable), DVD (Digital Versatile Disk) as a file in a format that can be installed in a storage circuit or in an executable format. It may be provided by being recorded on a computer-readable storage medium such as. Also, this program may be provided or distributed by being stored on a computer connected to a network such as the Internet and downloaded via the network. For example, this program is composed of modules including each functional unit described above. As actual hardware, the CPU reads out a program from a storage medium such as a ROM and executes it, so that each module is loaded onto the main storage device and generated on the main storage device.

According to at least one embodiment described above, it is possible to reduce the burden on the operator for setting the FOV.

While several embodiments have been described, these embodiments are provided by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations of embodiments can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

100 MRI apparatus 16 processing circuit 16a generation function 17 processing circuit 17b determination function 17c estimation function

Claims (9)

A magnetic resonance imaging apparatus that generates a diagnostic image covering a region of interest in a subject,
a generation unit that generates a first image including at least part of the subject prior to generation of the diagnostic image;
A determination unit that determines whether the first image includes the entire region of interest,
The generation unit generates the first image and the produces a second image with a different field of view,
Magnetic resonance imaging equipment. The region of interest is a region containing the minimum necessary anatomical features for the diagnostic image,
The magnetic resonance imaging apparatus according to claim 1. An estimating unit that estimates a position of the region of interest based on the first image when the determining unit determines that at least part of the region of interest is not included in the first image. prepared,
The generating unit generates, as the second image, an image of an imaging field of view set to include the entire region of interest based on the position of the region of interest estimated by the estimating unit.
3. The magnetic resonance imaging apparatus according to claim 1 or 2. The estimation unit estimates the position of the region of interest based on the anatomical feature points detected from the first image.
4. A magnetic resonance imaging apparatus according to claim 3. The estimation unit estimates the position of the region of interest by performing pattern matching between the first image and the model image.
4. A magnetic resonance imaging apparatus according to claim 3. The estimating unit inputs the first image to a trained model that outputs the position of the region of interest based on an image that does not include at least part of the region of interest. Estimate the position of
4. A magnetic resonance imaging apparatus according to claim 3. The determination unit detects an outline of the region of interest from the first image, and if at least a portion of the region of interest is missing, the first image includes at least a portion of the region of interest. determine that it is not
The magnetic resonance imaging apparatus according to any one of claims 1-6. When the anatomical feature point detected from the first image indicates a position different from the region of interest, the determination unit includes at least part of the region of interest in the first image. determine that it is not
The magnetic resonance imaging apparatus according to any one of claims 1-6. By moving the top plate on which the subject is placed, a first diagnostic image covering a first region of interest in the subject and a second region of interest different from the first region of interest are covered. A magnetic resonance imaging apparatus for generating a second diagnostic image,
a generation unit that generates, prior to generation of the first diagnostic image, a first image of an imaging field of view set to include the entire first region of interest;
A determination unit that determines whether the first image includes the entire second region of interest,
The generating unit, when the determining unit determines that at least part of the second region of interest is not included in the first image, generates the image of the sky prior to the second diagnostic image. generating a second image of an imaging field of view set to include all of the second region of interest by moving the plate;
Magnetic resonance imaging equipment.

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