WO2018044135A1

WO2018044135A1 - Dynamic tag magnetic resonance imaging device and method

Info

Publication number: WO2018044135A1
Application number: PCT/KR2017/009685
Authority: WO
Inventors: 박재석; 맹현경
Original assignee: 성균관대학교산학협력단
Priority date: 2016-09-05
Filing date: 2017-09-05
Publication date: 2018-03-08
Also published as: KR101784502B1

Abstract

A dynamic tag-based magnetic resonance imaging method according to an embodiment of the present invention comprises the steps of: (a) acquiring a magnetic resonance signal according to an application of an RF pulse; (b) acquiring dynamic tag information and static image information from the acquired magnetic resonance signal; and (c) generating a dynamic tag-based magnetic resonance image by combining the dynamic tag information and the static image information.

Description

Dynamic Tag Magnetic Resonance Imaging Device and Method

The present invention relates to a magnetic resonance imaging apparatus and method, and more particularly to a magnetic resonance imaging apparatus and method for displaying dynamic tag information.

Magnetic resonance imaging is a very sensitive test method. When a magnetic resonance image is acquired for an object moving periodically such as a heart, motion artifacts are highly likely to occur. As one of methods for resolving the distortion caused by the movement, researches on a magnetic resonance imaging technique capable of displaying dynamic tag information have been conducted in various forms.

In the dynamic tag magnetic resonance imaging technique, tag information is inserted into an image in the process of imaging a magnetic resonance signal, so that a mesh pattern or a grid pattern appears in the magnetic resonance image. When the object moves, you can see that the grid pattern expands or contracts, which makes it easier to see the movement of the object.

In order to obtain a dynamic tag magnetic resonance image, a process of multiplying a base pattern with a tag pattern having a specific fundamental frequency is performed, whereby the amplitude of the base image is spatially modulated. For example, the SPAMM (SPAtial Modulation of Magnetization) technique can be used, and the application of RF saturation pulses causes streaks or grid lines to be displayed.

According to the prior art, when directly Fourier transforming a dynamic tag magnetic resonance image, a phase image is obtained by extracting a peak region periodically appearing by the morphology characteristic of the dynamic tag magnetic resonance image in k-space, From this, the physical properties of the tissue (Displacement, Stiffness, etc) are quantified. At this time, the magnitude image and the magnitude image can be obtained at the same time. The resolution is very low, and the signal-to-noise ratio is low, so the utilization is very low. In addition, high-speed encoding of dynamic tag magnetic resonance images results in distortion and lower signal-to-noise ratio due to sampling times that are less than the Nyquist ratio.

In addition, when reconstructed by the conventional compression sensing technique, the smaller the number of sampling, the more limited the reconstruction of the peak region of the dynamic tag in k-space. Therefore, if the physical properties of the tissue are quantified using the dynamic tag information of the image reconstructed by compression sensing, the reliability of the value is lowered.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and some embodiments of the present invention provide a dynamic tag based magnetic resonance imaging apparatus and method for extracting dynamic tag information and static image information together. There is a purpose. However, the technical problem to be achieved by the present embodiment is not limited to the technical problem as described above, and other technical problems may exist.

As a technical solution for achieving the above technical problem, an embodiment of the present invention, to obtain a magnetic resonance signal according to the application of the RF pulse, obtain dynamic tag information and static image information from the obtained magnetic resonance signal, A dynamic tag based magnetic resonance image is generated by combining the dynamic tag information and the static image information.

According to the above-described problem solving means of the present invention, by extracting the dynamic tag information and the static image information from the magnetic resonance signal, based on the magnetic resonance that can easily confirm the displacement (displacement) or strain information (strain) information of the object You can restore the image.

1 is a diagram illustrating a magnetic resonance imaging apparatus according to an exemplary embodiment of the present invention.

2 is a diagram showing a pulse sequence associated with the operation of a conventional magnetic resonance imaging apparatus.

3 is a flowchart illustrating a dynamic tag magnetic resonance imaging method according to an embodiment of the present invention.

4 is a diagram for describing a dynamic tag magnetic resonance imaging method according to an exemplary embodiment of the present invention.

5 is a diagram illustrating a static image reconstruction process according to an embodiment of the present invention.

FIG. 6 is a diagram for describing an example of utilizing a dynamic tag magnetic resonance image, according to an exemplary embodiment.

7 is a view for explaining the performance of a dynamic tag magnetic resonance image according to an embodiment of the present invention.

According to an embodiment of the present invention, a dynamic tag based magnetic resonance imaging method includes: (a) obtaining a magnetic resonance signal according to an application of an RF pulse; (b) obtaining dynamic tag information and static image information from the obtained magnetic resonance signal; And (c) generating a dynamic tag based magnetic resonance image by combining the dynamic tag information and the static image information.

In addition, the magnetic resonance imaging apparatus for generating a dynamic tag based magnetic resonance image according to an embodiment of the present invention is a memory for storing a program for generating a dynamic tag based magnetic resonance image from the magnetic resonance signal and a processor for executing the program The processor may include acquiring a magnetic resonance signal according to an application of an RF pulse, acquiring dynamic tag information and static image information from the acquired magnetic resonance signal, and generating the dynamic tag information and the static signal according to the execution of the program. The image information is combined to generate a magnetic tag image based on dynamic tags.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is "connected" to another part, this includes not only "directly connected" but also "electrically connected" with another element in between. . In addition, when a part is said to "include" a certain component, which means that it may further include other components, except to exclude other components unless otherwise stated.

In the present specification, "magnetic resonance imaging (MRI)" refers to an image of an object acquired using the nuclear magnetic resonance principle.

In addition, “image” or “image” means multi-dimensional data composed of discrete elements, and includes a plurality of pixels in a two-dimensional image and a plurality of voxels in a three-dimensional image. It means consisting of.

In addition, the "object" is an object of imaging of the magnetic resonance imaging apparatus, and may include a person, an animal, or a part thereof. In addition, the subject may include various organs such as the heart, brain or blood vessels or various kinds of phantoms.

In addition, the "user" may be a doctor, a nurse, a medical imaging expert, or a device repair technician as a medical expert, but is not limited thereto.

In addition, the "pulse sequence" means a signal repeatedly applied by the magnetic resonance imaging apparatus. The pulse sequence may include a repetition time (TR), an echo time (Time to Echo, TE), or the like as a time parameter of the RF pulse.

Hereinafter, embodiments of the magnetic resonance imaging apparatus will be described with reference to the accompanying drawings.

The magnetic resonance imaging apparatus 1 may include an MRI scanner 10, a signal processor 20, a controller 40, a monitor 50, and an interface 60.

The MRI scanner 10 forms a magnetic field and generates a resonance phenomenon for the atomic nucleus, and the magnetic resonance image is photographed while the object is located inside the MRI scanner 10. The MRI scanner 10 includes a main magnet 12, a gradient coil 14, an RF coil 16, and the like, through which a static magnetic field and a gradient magnetic field are formed, and an RF signal is irradiated toward the object.

The main magnet 12, the gradient coil 14 and the RF coil 16 are disposed in the MRI scanner 10 according to a preset direction. The object may be positioned on a table that can be inserted into the cylinder along the horizontal axis of the cylinder, and the object may be positioned inside the bore of the MRI scanner 10 as the table moves.

The main magnet 12 generates a static magnetic field that aligns in a direction the direction of the magnetic dipole moment of the nuclei contained in the object.

The gradient coil 14 includes X coils, Y coils, and Z coils that generate gradient magnetic fields in the X, Y, and Z axis directions that are perpendicular to each other. The gradient coil 14 induces resonant frequencies differently for each part of the object to obtain location information of each part of the object.

The RF coil 16 may radiate an RF signal to the object and receive a magnetic resonance image signal emitted from the object. The RF coil 16 may output an RF signal having a frequency equal to the frequency of the precession toward the atomic nucleus that performs the precession, and then receive a magnetic resonance image signal emitted from the object.

For example, the RF coil 16 generates and applies an RF signal having a frequency corresponding to the atomic nucleus to the object in order to transition the nucleus from the low energy state to the high energy state. Thereafter, when the RF coil 16 stops transmitting the RF signal, the nuclear nucleus to which the electromagnetic wave is applied radiates an electromagnetic wave having a Lamor frequency while transitioning from a high energy state to a low energy state, and the RF coil 16 Receive the corresponding electromagnetic signal.

The RF coil 16 includes a transmitting RF coil for transmitting an RF signal having a radio frequency corresponding to the type of atomic nucleus and a receiving RF coil for receiving electromagnetic waves radiated from the atomic nucleus.

In addition, the RF coil 16 may be fixed to the MRI scanner 10 or may be in a removable form. The detachable RF coil 16 may be implemented in the form of a head RF coil, a chest RF coil, a leg RF coil, a neck RF coil, a shoulder RF coil, a wrist RF coil, and an ankle RF coil, which may be coupled to a part of an object. Can be.

The MRI scanner 10 may provide various information to a user or an object through a display, and may include a display 18 disposed outside and a display (not shown) disposed inside.

The signal processor 20 may control a gradient magnetic field formed inside the MRI scanner 10 according to a predetermined MR pulse sequence, and control transmission and reception of an RF signal and a magnetic resonance image signal.

The signal processor 20 may include a gradient magnetic field amplifier 22, a switching unit 24, an RF transmitter 26, and an RF receiver 28.

The gradient amplifier 22 drives the gradient coil 14 included in the MRI scanner 10, and generates a gradient signal that generates a gradient magnetic field under the control of the gradient magnetic field controller 44. To feed. By controlling the pulse signal supplied from the gradient amplifier 22 to the gradient coil 14, gradient magnetic fields in the X-axis, Y-axis, and Z-axis directions can be synthesized.

The RF transmitter 26 supplies an RF pulse to the RF coil 16 to drive the RF coil 16. The RF receiver 28 receives a magnetic resonance image signal transmitted after the RF coil 16 receives it.

The switching unit 24 may adjust a transmission / reception direction of the RF signal and the magnetic resonance image signal. For example, the RF signal is irradiated to the object through the RF coil 16 during the transmission operation, and the magnetic resonance image signal from the object is received through the RF coil 16 during the reception operation. The switching unit 24 controls the switching operation by the control signal from the RF control unit 46.

The interface unit 30 may command pulse sequence information to the control unit 40 according to a user's operation, and may transmit a command for controlling the operation of the entire MRI system. The interface unit 30 may include an image processor 36, an output unit 34, and an input unit 32 that process a magnetic resonance image signal received from the RF receiver 38.

The image processor 36 may process the MR image signal received from the RF receiver 38 to generate MR image data of the object.

The image processor 36 applies various signal processing such as amplification, frequency conversion, phase detection, low frequency amplification, filtering, etc. to the magnetic resonance image signal received by the RF receiver 38.

The image processing unit 36 may, for example, arrange digital data in k-space, and reconstruct the data into image data by performing two-dimensional or three-dimensional Fourier transform.

In addition, various signal processings applied by the image processor 36 to the magnetic resonance image signal may be performed in parallel. For example, signal processing may be applied in parallel to a plurality of magnetic resonance image signals received by a multi-channel RF coil to reconstruct the plurality of magnetic resonance image signals into image data.

The output unit 34 may output image data or reconstructed image data generated by the image processor 36 to the user. In addition, the output unit 34 may output information necessary for the user to operate the MRI system, such as a user interface (UI), user information, or object information. The output unit 34 may include a speaker, a printer, or various image display means.

The user may input object information, parameter information, scan conditions, pulse sequences, information on image composition or difference calculation, etc. through the input unit 32. The input unit 32 may include a keyboard, a mouse, a trackball, a voice recognizer, a gesture recognizer, a touch screen, and the like, and may include various input devices within a range apparent to those skilled in the art.

The controller 40 is a sequence controller 42 for controlling a sequence of signals formed in the MRI scanner 10, and a scanner controller 48 for controlling devices mounted on the MRI scanner 10 and the MRI scanner 10. It may include.

The sequence controller 42 includes a gradient magnetic field controller 44 that controls the gradient magnetic field amplifier 22, and an RF controller 46 that controls the RF transmitter 26, the RF receiver 28, and the switching unit 24. do. The sequence controller 42 may control the gradient amplifier 22, the RF transmitter 26, the RF receiver 28, and the switching unit 24 according to a pulse sequence received from the interface unit 30. The pulse sequence contains all the information necessary to control the gradient amplifier 22, the RF transmitter 26, the RF receiver 28 and the switch 24, for example a pulse applied to the gradient coil 14 It may include information on the strength of the pulse signal, an application time, an application timing, and the like.

The monitoring unit 50 monitors or controls the MRI scanner 10 or devices mounted on the MRI scanner 10. The monitoring unit 50 may include a system monitoring unit 52, an object monitoring unit 54, a table control unit 56, and a display control unit 58.

The system monitoring unit 52 includes a state of a static magnetic field, a state of a gradient magnetic field, a state of an RF signal, a state of an RF coil, a state of a table, a state of a device measuring body information of an object, a state of a power supply, a state of a heat exchanger, It can monitor and control the condition of the compressor.

The object monitoring unit 54 monitors the state of the object, and includes a camera for photographing the movement or position of the object, a respiration meter for measuring the respiration of the object, an ECG meter for measuring the electrocardiogram of the object, or a body temperature of the object. It may include a body temperature meter.

The table controller 56 controls the movement of the table where the object is located. The table controller 56 may control the movement of the table in synchronization with the sequence control signal output from the sequence controller 42. For example, in moving imaging of an object, the table control unit 56 may move the table according to sequence control, whereby the object has a larger FOV than the field of view of the MRI scanner. You can shoot.

The display control unit 58 controls the display positioned on the outside and the inside of the MRI scanner 10 on / off or a screen to be output to the display. In addition, when the speaker is located inside or outside the MRI scanner 10, the display controller 58 may control on / off of the speaker or sound to be output through the speaker.

The MRI scanner 10, the RF coil 16, the signal processing unit 20, the monitoring unit 50, the control unit 40, and the interface unit 30 may be wirelessly or wired to each other, and in the case of wirelessly connecting to each other. The apparatus may further include an apparatus (not shown) for synchronizing clocks therebetween. Communication between the MRI scanner 10, the RF coil 16, the signal processing unit 20, the monitoring unit 50, the control unit 40 and the interface unit 30 is a high-speed digital such as Low Voltage Differential Signaling (LVDS). Interface, asynchronous serial communication such as universal asynchronous receiver transmitter (UART), low delay network protocol such as error synchronization serial communication or controller area network (CAN), optical communication, and the like can be used. Communication methods can be used.

When a gradient magnetic field is formed by passing a current through the z-axis gradient coil 14z for a predetermined time, the resonance frequency is changed to be larger or smaller depending on the magnitude of the gradient magnetic field. When a high frequency signal corresponding to a specific position is applied through the RF coil 16, only protons in the cross section corresponding to the specific position cause resonance. Thus, the z-axis gradient coil 14z is used for slice selection. As the gradient of the gradient magnetic field formed in the z-axis direction is larger, a thinner slice may be selected.

When a slice is selected through the gradient magnetic field formed by the z-axis gradient coil 14z, the spindles constituting the slice all have the same frequency and the same phase, so that each spin cannot be distinguished.

At this time, when the gradient magnetic field is formed in the y-axis direction by the y-axis gradient coil 14y, the gradient magnetic field causes a phase shift so that the rows of the slices have different phases.

That is, when the y-axis gradient magnetic field is formed, the spindle of the row with the large gradient magnetic field is shifted in phase with the high frequency and the spindle of the row with the small gradient magnetic field is phase shifted with the lower frequency. When the y-axis gradient field disappears, each row of the selected slice undergoes a phase shift to have different phases, thereby distinguishing the rows. The gradient magnetic field generated by the y-axis gradient coil 14y is used for phase encoding.

The slice is selected through the gradient magnetic field formed by the z-axis gradient coil 14z, and the rows constituting the selected slice are distinguished by different phases through the gradient magnetic field formed by the y-axis gradient coil 14y. However, each spindle constituting a row has the same frequency and the same phase and cannot be distinguished.

In this case, when the gradient magnetic field is formed in the x-axis direction by the x-axis gradient coil 14x, the x-axis gradient magnetic field allows the spindles constituting each row to have different frequencies so as to distinguish each spin. The gradient magnetic field generated by the x-axis gradient coil 14x is used for frequency encoding.

As described above, the gradient magnetic field formed by the z-, y-, and x-axis gradient coils encodes a spatial position of each spindle through slice selection, phase encoding, and frequency encoding.

The magnetic resonance imaging apparatus 1 according to the exemplary embodiment of the present invention has a feature in the configuration of the image processor 36. In this case, the interface processor 30 including the image processor 36 or the image processor 36 may be implemented as a separate computing device, and may be based on a dynamic tag to be described later based on a memory and a processor mounted in the computing device. The operation of generating a magnetic resonance image is performed.

In this case, a program for generating a magnetic resonance image based on a dynamic tag is stored in the memory. A memory is a general term for a nonvolatile storage device that maintains stored information even when power is not supplied, and a volatile storage device that requires power to maintain stored information.

The processor generates a dynamic tag based magnetic resonance image based on the magnetic resonance signal received from the signal processor 20 according to the execution of the program stored in the memory.

In this case, the magnetic resonance signal may be image data including a plurality of frames representing a space according to the passage of time in the space-time encoding region (k, t-space).

As described above with reference to FIG. 1, in order to generate a magnetic resonance signal, the MRI scanner 10 adjusts another magnetic field using an electromagnetic pulse while fixing one magnetic field to excite a spin system. Can be. The MRI scanner 10 may form a magnetic field based on the plurality of gradient coils 14 to obtain a magnetic resonance signal for a space-time region.

As such, the processor of the magnetic resonance imaging apparatus 1 may receive a signal obtained from the MRI scanner 10. The magnetic resonance imaging apparatus 1 may generate a dynamic tag based magnetic resonance image using the magnetic resonance signal obtained from the MRI scanner 10.

3 is a flowchart illustrating a dynamic tag magnetic resonance imaging method according to an embodiment of the present invention, and FIG. 4 is a diagram illustrating a dynamic tag magnetic resonance imaging method according to an embodiment of the present invention.

First, a magnetic resonance signal generated by applying an RF pulse from the magnetic resonance imaging apparatus 1 is obtained (S310).

In the process of acquiring the magnetic resonance signal, the entire data of the unsampled state is acquired in the space-time encoding region (k, t-space), or the sampled data is obtained through an under sampling technique.

In the case of undersampling, we focus on the fact that the energy of the magnetic resonance image signal is concentrated in the low frequency region of the k-space, so that the low frequency region is sampled at high density and the high frequency region is randomly sampled at low density. Can be used.

Alternatively, a variable density undersampling technique is used to sample data at high density not only in the low frequency region but also in the peak region to maintain the inherent characteristics of the peaks that appear periodically in the k-space due to the morphology of the dynamic tag magnetic resonance image. Can be used.

That is, as shown in 400-2 of FIG. 4, the region where the peak appears in the k-space may be displayed in the form of white spots, and the magnetic resonance signal is sampled at a high density even for the region where the peak appears. For example, the magnetic resonance signal is sampled with high density not only for the white region shown in the center portion of 400-2 but also for the white region disposed in the diagonal direction.

400-1 of FIG. 4 shows a dynamic tag magnetic resonance image in the spatial domain, 400-2 shows a dynamic tag magnetic resonance image in the Fourier domain, and 400-3 is a k-space Shows variable density under sampling at, 400-4 shows probability density function in ky direction, and 400-5 shows sampling pattern results in kt space according to variable density under sampling. It is shown.

Referring to FIG. 3 again, dynamic tag information and static image information are obtained from a magnetic resonance signal obtained through variable density under sampling (S320).

The magnetic resonance signal X may be modeled in a form including a static image L, tag information T, and a noise component N as shown in the following equation.

In this case, X is a Casorati matrix,

is defined as (xt space). X includes dynamic tag magnetic resonance images that are continuous in time.

The process of obtaining the static image (L) and the tag information (T) is implemented through the process of solving the following equation.

At this time,

Represents the Kasorati matrix operator,

Represents the Hankel matrix operator,

Represents the nuclear norm.

Where d represents data measured in kt space, Fu represents an undersampled Fourier transform operator,

Represents Euclidian norm,

Represents the nucleus gambling. If the undersampling is not performed in the previous step, Equation 3 can be solved based on the entire data.

Meanwhile,

and

Denotes dictionary information for the static image L and dictionary information for the tag information T, respectively.

In the case of the tag information (T), since it changes slowly with time, by utilizing advance information that the similarity between successive time frame data is large, a random size patch is slid for each frame data to form a Kasorati matrix structure as shown in the following equation. Can be rearranged. In other words, each frame data is vectorized and stacked sequentially to generate a Kasorati matrix. In the case of the tag information T shown in Equation 4 below, it indicates that a Kasoratti matrix is generated for a total of M frame data. In addition, since the tag information T in the Kasorati matrix has a considerably high level of correlation with each other, it has a low rank characteristic.

In the case of the static image L, since the data of the region (stripe pattern or grid pattern) in which the tag information is located is missing, a process of restoring the image is performed using image interpolation. For example, the association between pixels around the missing pixel is used to recover the missing portion.

In order to restore the static image L as described above, an operation of acquiring an initial value for reconstruction of the static image L may be separately performed and used as advance information. For example, in the process of acquiring the magnetic resonance signal, the magnetic resonance signal for the reference image may be obtained without setting the dynamic tag, and the reference image may be generated therefrom and set as the initial value of the static image L. FIG. Alternatively, the dynamic tag magnetic resonance image obtained from the magnetic resonance signal acquired in the last step in time by using the characteristic that the tag becomes thinner in the image due to the T1 relaxation effect in the image acquisition process of the dynamic tag magnetic resonance image May be set as an initial value of the static image (L).

Meanwhile, to reconstruct the static image L, the data is rearranged in a Hankel structure, and the static image is reconstructed by applying a low rank completion algorithm.

As illustrated, a Hankel matrix may be generated by sliding patches of a predetermined size with respect to a plurality of static images generated at different times, and stacking by stacking data corresponding to each patch. A low order coefficient algorithm may be applied to the Hankel matrix to restore the static image. In this case, the plurality of static images may include a reference image set as the initial value described above or a dynamic tag magnetic resonance image acquired in the last step in time.

The dynamic tag magnetic resonance image is updated by adding the dynamic tag information and the static image information thus obtained, and the dynamic tag until the error between the updated dynamic tag magnetic resonance image and the magnetic resonance signal acquired in the space-time region is minimized. The process of separating and restoring the information and the static image information is repeated.

Next, the magnetic tag image based on the dynamic tag is obtained by combining the finally obtained dynamic tag information and the static image information (S330).

In the present invention, the physical information about the active state of the object may be checked by combining the dynamic tag information and the static image information. It will be described in more detail with reference to the drawings.

In the present invention, the dynamic tag information and the static image information can be obtained together from the magnetic resonance signal. The dynamic tag information thus obtained may be used to identify displacement or strain information of the object. For example, in order to non-invasively determine the degree of hardening of the liver (liver) can be used to determine the degree of movement of the liver by the movement of the heart. In this case, the degree of displacement of the object may be checked based on the dynamic tag information, and accordingly, the degree of liver hardening may be determined.

In addition, the static image information may be utilized as road map information. Thus, not only the information about the displacement of the object, but also the structure and functional aspects of the object may be checked.

As such, the image as shown in FIG. 6 may be generated by combining the dynamic tag information and the static image information.

(A), (b), (c) of FIG. 6 show the state of healthy liver, and (d), (e), (f) shows the state of liver with cirrhosis of the liver. In the case of a healthy liver, it can be seen that there are relatively many areas of high displacement represented by a red color (i.e., a portion of the liver shown at low brightness), and these images can quantitatively confirm the physical state of the object. have.

The picture shown in 700-1 of FIG. 7 is generated based on the prior art, and the picture shown in 700-2 is generated based on the present invention. The red areas in each figure (i.e. the low light levels in the liver) indicate where the movement is caused by the beating of the heart.

By the way, in the case of 700-1, not only the portion adjacent to the heart but also other regions are shown in red, and it can be confirmed that this is distorting the actual phenomenon. In the case of 700-2, almost no part of the area marked with red appears except the part adjacent to the heart, and thus it is confirmed that the physical property is more quantified.

An embodiment of the present invention may also be implemented in the form of a recording medium including instructions executable by a computer, such as a program module executed by the computer. Computer readable media can be any available media that can be accessed by a computer and includes both volatile and nonvolatile media, removable and non-removable media. In addition, computer readable media may include both computer storage media and communication media. Computer storage media includes both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Communication media typically includes computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave, or other transmission mechanism, and includes any information delivery media.

The foregoing description of the present invention is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

Claims

In a magnetic tag imaging method based on a dynamic tag,

(a) obtaining a magnetic resonance signal according to the application of an RF pulse;

(b) obtaining dynamic tag information and static image information from the obtained magnetic resonance signal; And

and (c) generating a dynamic tag based magnetic resonance image by combining the dynamic tag information and the static image information.
The method of claim 1,

Step (a) is a dynamic tag applying a variable density under sampling technique for sampling the magnetic resonance signal with a relatively higher density than the rest of the peak region periodically appearing in the k-space of the dynamic tag based magnetic resonance signal Based Magnetic Resonance Imaging Method.
The method of claim 1,

And repeating steps (b) and (c) until the error between the dynamic tag-based magnetic resonance image and the magnetic resonance signal acquired in the space-time region is minimized.
The method of claim 1,

The step (b) is to obtain the dynamic tag information and static image information through the process of solving the optimization problem corresponding to Equation 1 below the dynamic tag-based magnetic resonance imaging method.

<Equation 1>

Where d represents data measured in kt space, Fu represents an undersampled Fourier transform operator,
Represents Euclidian norm,
Represents the nuclear norm,
and
Denotes dictionary information on the static image L and dictionary information on the tag information T, respectively.
Represents the Kasorati matrix operator,
Represents the Hankel matrix operator.
The method of claim 4, wherein

The step (b) is preliminary information on the static image (L), the dynamic image obtained from the magnetic resonance signal obtained in the last step in time when the reference image or the magnetic resonance signal obtained without setting the dynamic tag A dynamic tag based magnetic resonance imaging method using tag magnetic resonance imaging.
The method of claim 1,

The MR image based on the dynamic tag may include displacement information according to time of an object acquired from the dynamic tag information, and include structure information of the object obtained from the static image information. Way.
In a magnetic resonance imaging apparatus for generating a magnetic resonance image based on a dynamic tag,

Memory storing a program for generating a dynamic tag-based magnetic resonance image from the magnetic resonance signal received from the MRI scanner and

A processor for executing the program,

The processor acquires a magnetic resonance signal according to the application of an RF pulse, obtains dynamic tag information and static image information from the obtained magnetic resonance signal, and combines the dynamic tag information and the static image information according to execution of the program. Dynamic tag based magnetic resonance imaging apparatus for generating a dynamic tag based magnetic resonance image.
The method of claim 7, wherein

The processor applies a dynamic-density undersampling technique for sampling a magnetic resonance signal with a relatively higher density than that of the rest of the peak regions that appear periodically in the k-space upon acquisition of the dynamic tag-based magnetic resonance signal. Magnetic Resonance Imaging Device.
The method of claim 7, wherein

The processor acquires the dynamic tag information and the static image information and combines the dynamic tag information and the static image information until the error between the dynamic tag based magnetic resonance image and the magnetic resonance signal acquired in the space-time region is minimized. Dynamic tag-based magnetic resonance imaging method to repeat the steps of generating a dynamic tag-based magnetic resonance image by using.
The method of claim 7, wherein

The processor acquires the dynamic tag information and the static image information by solving an optimization problem corresponding to Equation 1 below.

<Equation 1>

Where d represents data measured in kt space, Fu represents an undersampled Fourier transform operator,
Represents Euclidian norm,
Represents the nuclear norm,
and
Denotes dictionary information on the static image L and dictionary information on the tag information T, respectively.
Represents the Kasorati matrix operator,
Represents the Hankel matrix operator.
The method of claim 10,

The processor may be a preliminary information on the static image (L), the dynamic tag obtained from the magnetic resonance signal obtained in the last step in time at the time of obtaining the reference image or the magnetic resonance signal obtained without setting the dynamic tag A dynamic tag based magnetic resonance imaging apparatus using magnetic resonance imaging.
The method of claim 7, wherein

The MR image based on the dynamic tag may include displacement information according to time of the object obtained from the dynamic tag information, and include structure information of the object obtained from the static image information. Device.