WO2018221832A1 - Procédé de génération d'image par résonance magnétique et appareil d'imagerie par résonance magnétique associé - Google Patents

Procédé de génération d'image par résonance magnétique et appareil d'imagerie par résonance magnétique associé Download PDF

Info

Publication number
WO2018221832A1
WO2018221832A1 PCT/KR2018/001493 KR2018001493W WO2018221832A1 WO 2018221832 A1 WO2018221832 A1 WO 2018221832A1 KR 2018001493 W KR2018001493 W KR 2018001493W WO 2018221832 A1 WO2018221832 A1 WO 2018221832A1
Authority
WO
WIPO (PCT)
Prior art keywords
magnetic resonance
signal
pulse sequence
fid
imaging
Prior art date
Application number
PCT/KR2018/001493
Other languages
English (en)
Inventor
Jae Seok Park
Eun Ji Lim
Hyun Kyoung Maeng
Jun Sik Park
Original Assignee
Research & Business Foundation Sungkyunkwan University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Research & Business Foundation Sungkyunkwan University filed Critical Research & Business Foundation Sungkyunkwan University
Publication of WO2018221832A1 publication Critical patent/WO2018221832A1/fr

Links

Images

Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves 
    • A61B5/055—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves  involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/48—NMR imaging systems
    • G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
    • G01R33/56—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
    • G01R33/561—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution by reduction of the scanning time, i.e. fast acquiring systems, e.g. using echo-planar pulse sequences
    • G01R33/5615—Echo train techniques involving acquiring plural, differently encoded, echo signals after one RF excitation, e.g. using gradient refocusing in echo planar imaging [EPI], RF refocusing in rapid acquisition with relaxation enhancement [RARE] or using both RF and gradient refocusing in gradient and spin echo imaging [GRASE]
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/48—NMR imaging systems
    • G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
    • G01R33/56—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
    • G01R33/565—Correction of image distortions, e.g. due to magnetic field inhomogeneities
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/288—Provisions within MR facilities for enhancing safety during MR, e.g. reduction of the specific absorption rate [SAR], detection of ferromagnetic objects in the scanner room
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/48—NMR imaging systems
    • G01R33/483—NMR imaging systems with selection of signals or spectra from particular regions of the volume, e.g. in vivo spectroscopy
    • G01R33/4833—NMR imaging systems with selection of signals or spectra from particular regions of the volume, e.g. in vivo spectroscopy using spatially selective excitation of the volume of interest, e.g. selecting non-orthogonal or inclined slices
    • G01R33/4835—NMR imaging systems with selection of signals or spectra from particular regions of the volume, e.g. in vivo spectroscopy using spatially selective excitation of the volume of interest, e.g. selecting non-orthogonal or inclined slices of multiple slices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/48—NMR imaging systems
    • G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
    • G01R33/56—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
    • G01R33/561—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution by reduction of the scanning time, i.e. fast acquiring systems, e.g. using echo-planar pulse sequences
    • G01R33/5615—Echo train techniques involving acquiring plural, differently encoded, echo signals after one RF excitation, e.g. using gradient refocusing in echo planar imaging [EPI], RF refocusing in rapid acquisition with relaxation enhancement [RARE] or using both RF and gradient refocusing in gradient and spin echo imaging [GRASE]
    • G01R33/5617—Echo train techniques involving acquiring plural, differently encoded, echo signals after one RF excitation, e.g. using gradient refocusing in echo planar imaging [EPI], RF refocusing in rapid acquisition with relaxation enhancement [RARE] or using both RF and gradient refocusing in gradient and spin echo imaging [GRASE] using RF refocusing, e.g. RARE
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/10—Image acquisition modality
    • G06T2207/10072—Tomographic images
    • G06T2207/10088—Magnetic resonance imaging [MRI]

Definitions

  • the present disclosure relates to a method of generating a magnetic resonance image and a magnetic resonance imaging apparatus therefor, and more particularly to a method of generating a magnetic resonance image from which artifacts caused by a free induction decay (FID) signal are removed.
  • FID free induction decay
  • a spin echo technique has been most widely used in the field of magnetic resonance imaging technology and applies a 90° excitation pulse followed by a 180° refocusing pulse to an object to acquire an echo signal for imaging.
  • the spin echo technique has received a lot of attention since it can generate an image with excellent signal to noise ratio (SNR) and contrast ratio.
  • SNR signal to noise ratio
  • the spin echo technique has developed in a way that applies a 90° excitation pulse followed by multiple refocusing pulses in order to reduce scan time.
  • a specific absorption rate (SAR) for an inspection target object is increased, which causes a stability problem. Therefore, various fast spin echo techniques have developed in a way that intentionally applies refocusing pulses with a flip angle of less than 180°.
  • the flip angle of a refocusing pulse is adjusted to be less than 180° due to instability of a system or on purpose to solve the SAR problem, an unintended free induction decay (FID) signal is also acquired together with an echo signal.
  • the FID signal acts as an artifact in a magnetic resonance image and thus lowers the SNR. Therefore, in recent years, research for maintaining high SNR and contrast ratio of the spin echo technique while securing the safety of an inspection target object has been actively conducted.
  • each slice has been scanned and then applied with a phase-inverted refocusing pulse to perform repeated scanning, and, thus, an artifact has been removed by adding an original image and a phase-inverted image.
  • repeated scanning is performed to each slice, and, thus, an increase in the number of slices may cause an excessive increase in scan time.
  • the present disclosure has been conceived to solve the above-described problems of the conventional technology, and some exemplary embodiments of the present disclosure provide a magnetic resonance imaging apparatus and method for quantifying a FID signal to remove an artifact caused by the FID signal from a magnetic resonance signal acquired using an imaging pulse sequence.
  • some exemplary embodiments of the present disclosure are provided to quantify a FID signal while suppressing an excessive increase in scan time.
  • a first aspect of the present disclosure provides a method of generating a magnetic resonance image: acquiring a magnetic resonance signal by applying an imaging pulse sequence for multiple slices to an object; acquiring a free induction decay (FID) signal by applying a calibration pulse sequence with a phase-inverted refocusing pulse for one of the multiple slices to the object; subtracting the FID signal from the magnetic resonance signal; and generating a magnetic resonance image on the basis of the magnetic resonance signal from which the FID signal is subtracted.
  • FID free induction decay
  • a second aspect of the present disclosure provides a magnetic resonance imaging apparatus including a memory in which a program configured to give pulse sequence information to a MRI scanner and generate a magnetic resonance image on the basis of a magnetic resonance signal received from the MRI scanner, and a processor configured to execute the program.
  • the processor acquires a magnetic resonance signal by applying an imaging pulse sequence for multiple slices, acquires a FID signal by applying a calibration pulse sequence with a phase-inverted refocusing pulse for one of the multiple slices, subtracts the FID signal from the magnetic resonance signal, and generates a magnetic resonance image on the basis of the magnetic resonance signal from which the FID signal is subtracted.
  • a third aspect of the present disclosure provides a computer-readable storage medium in which a program configured to implement the method of the first aspect is recorded.
  • a calibration pulse sequence requiring a single or more TR is added to various fast pulse sequences based on a spin echo technique, and, thus, it is possible to solve a safety problem for an inspection target object and also possible to maintain high SNR and contrast ratio while suppressing an excessive increase in scan time.
  • FIG. 1 is a diagram illustrating a magnetic resonance imaging apparatus according to an exemplary embodiment of the present disclosure.
  • FIG. 2 is a flowchart illustrating a magnetic resonance imaging method according to an exemplary embodiment of the present disclosure.
  • FIG. 3 illustrates an example of a region where a FID signal is emitted by an imaging pulse sequence according to an exemplary embodiment of the present disclosure.
  • FIG. 4 illustrates a method of extracting a FID signal according to an exemplary embodiment of the present disclosure.
  • FIG. 5 is a diagram illustrating the result of extraction of a FID signal by applying a calibration pulse sequence to a slice included in a phantom according to an exemplary embodiment of the present disclosure.
  • FIG. 6 is a diagram illustrating the result of generation of a magnetic resonance image from which artifacts caused by a FID signal are removed using the FID signal extracted in FIG. 5 according to an exemplary embodiment of the present disclosure.
  • connection or coupling that is used to designate a connection or coupling of one element to another element includes both a case that an element is “directly connected or coupled to” another element and a case that an element is “electronically connected or coupled to” another element via still another element.
  • the term “comprises or includes” and/or “comprising or including” used in the document means that one or more other components, steps, operation and/or existence or addition of elements are not excluded in addition to the described components, steps, operation and/or elements unless context dictates otherwise.
  • magnetic resonance image refers to an image of an object acquired by using the nuclear magnetic resonance principle.
  • image refers to multi-dimensional data composed of discrete elements and may include multiple pixels for 2-dimensinal image and multiple voxels for 3-dimensional image.
  • the term "object” refers to a target to be taken by the MRI apparatus and may include a person or animal or a part thereof. Also, the object may include various organs such as the heart, brain, or blood vessels or a variety of phantoms.
  • the term "user” refers to a medical expert such as a doctor, a nurse, a medical imaging expert, and the like or an engineer repairing a medical apparatus, but is not limited thereto.
  • pulse sequence refers to a signal repeatedly applied from the MRI apparatus.
  • the pulse sequence is a time parameter for a RF pulse and may include Time of Repetition (TR) or Time to Echo (TE).
  • TR Time of Repetition
  • TE Time to Echo
  • FIG. 1 is a diagram illustrating a magnetic resonance imaging apparatus according to an exemplary embodiment of the present disclosure.
  • a magnetic resonance imaging apparatus 1 may include a MRI scanner 10, a signal processing unit 20, a monitoring unit 50, a control unit 40, and an interface unit 60.
  • the MRI scanner 10 generates a magnetic field and generates a resonance with respect to an atomic nucleus, and a magnetic resonance image is taken while an object is present inside the MRI scanner 10.
  • the MRI scanner 10 includes a main magnet 12, a gradient coil 14, a RF coil, and the like and thus generates a static magnetic field and a gradient magnetic field and irradiates a RF signal toward the object.
  • the main magnet 12, the gradient coil 14, and the RF coil 16 are arranged within the MRI scanner 10 along a predetermined direction.
  • the object may be positioned on a table which can be inserted into a cylinder along a horizontal axis of the cylinder, and as the table moves, the object can be positioned within a bore of the MRI scanner 10.
  • the main magnet 12 generates a static magnetic field that aligns for aligning magnetic dipole moments of atomic nucleuses included in the object in a certain direction.
  • the gradient coil 14 includes X, Y, and Z coils that respectively generate gradient magnetic fields in X-axis, Y-axis, and Z-axis directions orthogonal to each other.
  • the gradient coil 14 may induce different resonance frequencies for respective parts of the object and provide position information of each part of the object.
  • the RF coil 16 may irradiate a RF signal to the object and receive a magnetic resonance image signal emitted from the object.
  • the RF coil 16 may output a RF signal having the same frequency as a precessional motion toward an atomic nucleus performing the precessional motion and then receive a magnetic resonance image signal emitted from the object.
  • the RF coil 16 may generate a RF signal having a frequency corresponding to the atomic nucleus and apply the RF signal to the object. Then, when the RF coil 16 stops the transmission of the RF signal, the atomic nucleus to which the electromagnetic wave was applied may transition from the high energy level to the low energy level and emit an electromagnetic wave having a Larmor frequency, and the RF coil 16 receives a signal of the electromagnetic wave.
  • the RF coil 16 includes a RF transmission coil that transmits a RF signal having a radio frequency corresponding to the kind of an atomic nucleus and a RF reception coil that receives an electromagnetic wave emitted from an atomic nucleus.
  • the RF coil 16 may be fixed to the MRI scanner 10 or may be detachably attached to the MRI scanner 10.
  • the detachable RF coil 16 may be implemented as 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 can be coupled to a part of the object.
  • the MRI scanner 10 may provide various kinds of information to a user or the object through a display and may include a display 18 provided outside the MRI scanner 10 and a display (not illustrated) provided inside the MRI scanner 10.
  • the signal processing unit 20 may control a gradient magnetic field which is formed inside the MRI scanner 10 and control transmission and reception of a RF signal and a magnetic resonance image signal according to a predetermined MR pulse sequence (i.e., pulse train).
  • a predetermined MR pulse sequence i.e., pulse train
  • the signal processing unit 20 may include a gradient amplifier 22, a switching unit 24, a RF transmitter 26, and a RF receiver 28.
  • the gradient amplifier 22 drives the gradient coil 14 included in the MRI scanner 10 and supplies the gradient coil 14 with a pulse signal that generates a gradient magnetic field under the control of a gradient magnetic field controller 44.
  • Gradient magnetic fields in the X-axis, Y-axis, and Z-axis directions may be synthesized by controlling the pulse signal supplied from the gradient amplifier 22 to the gradient coil 92.
  • the RF transmitter 26 drives the RF coil 16 by supplying a RF pulse to the RF coil 16.
  • the RF receiver 28 receives a magnetic resonance image signal received and then transferred by the RF coil 16.
  • the switching unit 24 may adjust a transmission/reception direction of each of a RF signal and a magnetic resonance image signal. For example, in a transmission mode, the switching unit 24 may irradiate a RF signal to the object through the RF coil 16, and in a reception mode, the switching unit 24 may receive a magnetic resonance image signal from the object through the RF coil 16. The switching unit 24 is controlled by a control signal from a RF controller 46.
  • the interface unit 30 may give pulse sequence information to the control unit 40 and transfer a command to control an operation of the entire MRI system at the same time by manipulation of the user.
  • the interface unit 30 may include an image processing unit 36 configured to process a magnetic resonance image signal received by the RF receiver 28, an output unit 34, and an input unit 32.
  • the image processing unit 36 may process a magnetic resonance image signal received by the RF receiver 28 and generate MR image data for the object 10.
  • the image processing unit 36 may perform various signal processing operations, such as amplification, frequency conversion, phase detection, low-frequency amplification, and filtering, to the magnetic resonance image signal received by the RF receiver 28.
  • the image processing unit 36 may arrange digital data in a k-space and perform a 2-dimensioanl or 3-dimensional Fourier transform to the digital data to reconfigure the digital data into image data.
  • the image processing unit 36 may parallelly perform the signal processing operations to the magnetic resonance image signal.
  • the image processing unit 36 may parallelly perform a signal processing operation to multiple magnetic resonance image signals received by a multi-channel RF coil to reconfigure the multiple magnetic resonance image signals into image data.
  • the output unit 34 may output the image data generated or reconfigured by the image processing unit 36 to the user. Further, the output unit 34 may output information, which is necessary for the user to manipulate 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 devices.
  • the input unit 32 enables the user to input object information, parameter information, a scanning condition, a pulse sequence, information on image synthesis or differential operation, and the like.
  • the input unit 32 may include a keyboard, a mouse, a trackball, a voice recognizer, a gesture recognizer, a touch screen, etc., and include various input devices within a scope obvious to those skilled in the art.
  • the control unit 40 may include a sequence controller 42 configured to control a sequence of signals generated within the MRI scanner 10 and a scanner controller 48 configured to control the MRI scanner 10 and devices provided in the MRI scanner 10.
  • the sequence controller 42 includes the gradient magnetic field controller 44 configured to control the gradient amplifier 22 and the RF controller 46 configured to control the RF transmitter 26, the RF receiver 28, and the switching unit 24.
  • 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 may include all information required to control the gradient amplifier 22, the F transmitter 26, the RF receiver 28, and the switching unit 24, and may include, for example, information on an intensity of a pulse signal applied to the gradient coil 14, an application time, an application timing, and the like.
  • the monitoring unit 50 may monitor or control the MRI scanner 10 or the devices provided in the MRI scanner 10.
  • the monitoring unit 50 may include a system monitor 52, an object monitor 54, a table controller 56, and a display controller 58.
  • the system monitor 52 may monitor and control a state of a static magnetic field, a state of a gradient magnetic field, a state of a RF signal, a state of a RF coil, a state of a table, a state of a device that measures body information of the object, a power supply state, a state of a heat exchanger, a state of a compressor, and the like.
  • the object monitor 54 monitors a state of the object, and may include a camera for taking a picture of a movement or position of the object, a breath measurer for measuring a breath of the object, an electrocardiogram (ECG) measurer for measuring an ECG of the object, or a body temperature measurer for measuring a body temperature of the object.
  • a camera for taking a picture of a movement or position of the object
  • a breath measurer for measuring a breath of the object
  • ECG electrocardiogram
  • body temperature measurer for measuring a body temperature of the object.
  • the table controller 56 controls a movement of the table on which the object is positioned.
  • the table controller 56 may control the movement of the table according to a sequence control signal output by the sequence controller 42. For example, during moving imaging of the object, the table controller 56 may move the table according to the sequence control and thus take a picture of the object in a field of view (FOV) greater than that of the MRI scanner.
  • FOV field of view
  • the display controller 58 controls an on/off operation of the displays respectively positioned outside and inside the MRI scanner 10 or screen images output on the displays. Also, in the case where a speaker is positioned inside or outside the MRI scanner 10, the display controller 58 may control the speaker to be turned on or off or may control 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 connected to each other in a wireless or wired manner, and when they are connected in a wireless manner, the magnetic resonance imaging apparatus 1 may further include an apparatus (not illustrated) 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 may be performed by using a high-speed digital interface such as low voltage differential signaling (LVDS), asynchronous serial communication such as a universal asynchronous receiver transmitter (UART), a low-delay network protocol such as error synchronous serial communication or a controller area network (CAN), optical communication, or any of other various communication methods within a scope obvious to those skilled in the art.
  • LVDS low voltage differential signaling
  • UART universal asynchronous receiver transmitter
  • CAN controller area network
  • optical communication or any of other various communication methods within a scope obvious to those skilled in the art.
  • the magnetic resonance imaging apparatus 1 is characterized by a configuration of the interface unit 30.
  • the interface unit 30 may be implemented in the form of a separate computing system and performs an operation of generating a magnetic resonance image on the basis of a memory and a processor installed in the computing system.
  • the memory stores a program configured to generate a magnetic resonance image.
  • the memory may collectively refer to a non-volatile storage device that retains information stored therein even when power is not supplied and a volatile storage device that requires power to retain information stored therein.
  • the processor Upon execution of the program stored in the memory, the processor gives pulse sequence information including refocusing pulses of 180° or less and then generates a magnetic resonance image using a magnetic resonance signal emitted from the object.
  • the magnetic resonance signal may be image data including multiple frames displaying spaces with the passage of time in a spatio-temporal encoding area (k,t-space).
  • the MRI scanner 10 may excite a spin system by adjusting a magnetic field with an electromagnetic pulse while fixing another magnetic field in order to generate a magnetic resonance signal according to a pulse sequence command. Further, the MRI scanner 10 may generate a magnetic field on the basis of multiple gradient coils 14 to acquire a magnetic resonance signal for a spatio-temporal area.
  • the processor of the magnetic resonance imaging apparatus 1 may receive the acquired signal from the MRI scanner 10. Further, the magnetic resonance imaging apparatus 1 may generate a magnetic resonance image from which artifacts caused by a FID signal are removed by using the magnetic resonance signal acquired from the MRI scanner 10.
  • FIG. 2 is a flowchart illustrating a magnetic resonance imaging method according to an exemplary embodiment of the present disclosure.
  • the magnetic resonance imaging apparatus 1 acquires a magnetic resonance signal by applying an imaging pulse sequence for multiple slices to the object (S110).
  • the imaging pulse sequence may include various pulse sequences based on a spin echo technique and may be composed of multiple refocusing pulses having a fixed and/or variable flip angle of 180° or less.
  • the imaging pulse sequence may be based on, for example, fast spin echo (FSE), turbo spin echo (TSE), gradient and spin echo (GRASE), or combinations thereof.
  • the imaging pulse sequence is configured to have a long echo train length (ELT) and a short echo spacing (ESP), it is desirable to use a refocusing pulse with short duration.
  • the duration of a pulse is in inverse proportion to the spatial bandwidth of the pulse, and, thus, it is desirable to use a pulse having a spatial bandwidth corresponding to or greater than a field of view (FOV) in a slice direction.
  • the refocusing pulse according to an exemplary embodiment of the present disclosure may be a refocusing pulse having a wide spatial bandwidth (i.e., wide-band) including all of multiple slices to be imaged or may be a non-selective refocusing pulse.
  • a free induction decay (FID) signal generated by a wide-band refocusing pulse or a non-selective refocusing pulse may be received from a region 302 corresponding to the FOV in the slice direction except a slice region 301 as illustrated in FIG. 3.
  • FID free induction decay
  • a FID signal is an instable signal generated when magnetized atomic nucleuses are dephased, and in the case where the imaging pulse sequence intentionally includes a refocusing pulse with a flip angle of less than 180° due to instability of the system or on purpose to solve the SAR problem, the FID signal may be unintendedly generated and may affect a final image. That is, since the magnetic resonance imaging apparatus 1 uses a refocusing pulse of 180° or less, the magnetic resonance imaging apparatus 1 receives a magnetic resonance signal including a FID signal as well as an echo signal, and the FID signal acts as an artifact in an image and thus lowers a SNR and a contrast ratio of the image. Therefore, the magnetic resonance imaging apparatus 1 removes the FID signal from the magnetic resonance signal acquired from the imaging pulse sequence by performing the following operation and thus suppresses a decrease in the SNR and contrast ratio of the image.
  • the magnetic resonance imaging apparatus 1 acquires a FID signal by applying a calibration pulse sequence with a phase-inverted refocusing pulse for one of multiple slices (S120).
  • the calibration pulse sequence requires a single or more TR and may be applied earlier or later than the imaging pulse sequence. Otherwise, the calibration pulse sequence may be applied in the middle of the imaging pulse sequence. For example, as illustrated in FIG. 4, an imaging pulse sequence 410 corresponding to a slice is applied and then, a calibration pulse sequence 420 may be applied to the object. An modified imaging pulse sequence is applied as the calibration pulse sequence. A refocusing pulse's phase contained in the imaging pulse sequence is inverted, and this calibration pulse sequence 420 with a phase inverted refocusing pulse is applied to the object.
  • the magnetic resonance imaging apparatus 1 may acquire a first magnetic resonance signal including an echo signal 401 and a FID signal 402a corresponding to the slice from the imaging pulse sequence 410 and then acquire a second magnetic resonance signal including the echo signal 401 and a phase-inverted FID signal 402b corresponding to the same slice from the calibration pulse sequence 420. Then, the magnetic resonance imaging apparatus 1 may extract the FID signal from which the echo signal 401 is removed by subtracting the first magnetic resonance signal and the second magnetic resonance signal. The extracted FID signal may be twice of the intensity of the FID signal 402a or the FID signal 402b.
  • FIG. 5 is a diagram illustrating the result of extraction of a FID signal 530 by applying a calibration pulse sequence to a slice included in a phantom according to an exemplary embodiment of the present disclosure.
  • the phantom is divided into first to fifth slices 610 to 650 as illustrated in FIG. 6 and the calibration pulse sequence is applied to a third slice 630. That is, a first magnetic resonance signal 510 is illustrated by imaging a magnetic resonance signal acquired from an imaging pulse sequence for the third slice 630, and a second magnetic resonance signal 520 is illustrated by imaging a magnetic resonance signal acquired from a calibration pulse sequence with phase-inverted refocusing pulses in the imaging pulse sequence.
  • the extracted FID signal 530 is emitted from a region greater than the third slice 630 as described above with reference to FIG. 3 and thus may be identical or similar to FID signals which can be generated from the imaging pulse sequence for the first to fifth slices 510 to 650.
  • the magnetic resonance imaging apparatus 1 subtracts the FID signal from the acquired magnetic resonance signal (S130).
  • the magnetic resonance imaging apparatus 1 may extract an echo signal suitable for imaging by removing the FID signal from the magnetic resonance signal.
  • the magnetic resonance imaging apparatus 1 generates a magnetic resonance image on the basis of the magnetic resonance signal from which the FID signal is subtracted (S140). That is, the magnetic resonance imaging apparatus 1 generates a magnetic resonance image using an echo signal, and, thus, it is possible to solve a SAR problem for the object and also possible to generate a magnetic resonance image having high SNR and contrast ratio.
  • the imaging pulse sequence may include an excitation pulse for simultaneously magnetizing two or more slices based on simultaneous multi-slice imaging.
  • FIG. 6 is a diagram illustrating the result of generation of a magnetic resonance image from which artifacts caused by a FID signal are removed using the FID signal extracted in FIG. 5 according to an exemplary embodiment of the present disclosure. That is, the magnetic resonance imaging apparatus 1 may subtract the FID signal 530 acquired using the third slice 630 from the magnetic resonance signals acquired from the first to fifth slices 610 to 650 and thus remove artifacts caused by the FID signal 530 from all the slices 610 to 650.
  • the magnetic resonance imaging apparatus 1 adds a calibration pulse sequence requiring a single or more TR, and, thus, it is possible to solve a stability problem for a fast pulse sequence based on the spin echo technique and also possible to maintain high SNR and contrast ratio which is an advantage of the spin echo technique while suppressing an excessive increase in scan time.
  • An exemplary embodiment of the present disclosure can be embodied in a storage medium including instruction codes executable by a computer such as a program module executed by the computer.
  • a computer-readable medium can be any usable medium which can be accessed by the computer and includes all volatile/non-volatile and removable/non-removable media. Further, the computer-readable medium may include all computer storage.
  • the computer storage medium includes all volatile/non-volatile and removable/non-removable media embodied by a certain method or technology for storing information such as computer-readable instruction code, a data structure, a program module or other data.

Landscapes

  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • General Health & Medical Sciences (AREA)
  • Radiology & Medical Imaging (AREA)
  • Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Signal Processing (AREA)
  • General Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Medical Informatics (AREA)
  • Pathology (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Biophysics (AREA)
  • Molecular Biology (AREA)
  • Surgery (AREA)
  • Animal Behavior & Ethology (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Magnetic Resonance Imaging Apparatus (AREA)

Abstract

Cette divulgation concerne un procédé de génération d'une image par résonance magnétique selon un mode de réalisation donné à titre d'exemple comprenant l'acquisition d'un signal de résonance magnétique par application d'une séquence d'impulsions d'imagerie aux multiples tranches d'un objet, l'acquisition d'un signal de décroissance d'induction libre (FID) par application d'une séquence d'impulsions d'étalonnage comprenant une impulsion de refocalisation à inversion de phase à l'une des multiples tranches de l'objet, la soustraction du signal FID du signal de résonance magnétique, et la génération d'une image par résonance magnétique en fonction du signal de résonance magnétique dont le signal FID est soustrait.
PCT/KR2018/001493 2017-05-29 2018-02-05 Procédé de génération d'image par résonance magnétique et appareil d'imagerie par résonance magnétique associé WO2018221832A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR1020170066373A KR101949491B1 (ko) 2017-05-29 2017-05-29 자기 공명 영상 생성 방법 및 그 자기 공명 영상 처리 장치
KR10-2017-0066373 2017-05-29

Publications (1)

Publication Number Publication Date
WO2018221832A1 true WO2018221832A1 (fr) 2018-12-06

Family

ID=64455992

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/KR2018/001493 WO2018221832A1 (fr) 2017-05-29 2018-02-05 Procédé de génération d'image par résonance magnétique et appareil d'imagerie par résonance magnétique associé

Country Status (2)

Country Link
KR (1) KR101949491B1 (fr)
WO (1) WO2018221832A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003087864A1 (fr) * 2002-04-16 2003-10-23 Koninklijke Philips Electronics N.V. Imagerie par resonance magnetique multiecho a t1 pondere
JP3544782B2 (ja) * 1996-04-16 2004-07-21 株式会社東芝 磁気共鳴診断装置
JP2004261619A (ja) * 2004-06-25 2004-09-24 Toshiba Corp 磁気共鳴イメージング装置
WO2008042370A1 (fr) * 2006-10-03 2008-04-10 Duke University Systèmes et procédés permettant d'évaluer le transfert gazeux pulmonaire par irm avec du 129xe hyperpolarisé
WO2012151551A2 (fr) * 2011-05-04 2012-11-08 Oregon Health And Science University Méthode et appareil pour utiliser l'imagerie par résonance magnétique en vue de l'examen et du contrôle du cartilage

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9474454B2 (en) * 2010-10-20 2016-10-25 Advanced Mri Technologies Llc MRI using faster multiplexed echo planar imaging (EPI) pulse sequences
US9689948B2 (en) * 2011-10-03 2017-06-27 Regents Of The University Of Minnesota System and method for reducing radio frequency peak voltage and power requirements in magnetic resonance imaging using time-shifted multiband radio frequency pulses
DE102012204434B3 (de) * 2012-03-20 2013-07-11 Siemens Aktiengesellschaft Mehrschicht-MRI-Anregung mit simultaner Refokussierung aller angeregten Schichten
KR101967242B1 (ko) * 2012-11-14 2019-04-09 삼성전자주식회사 자기공명영상 시스템 및 자기공명영상 방법
KR101967244B1 (ko) * 2012-12-05 2019-04-09 삼성전자주식회사 자기 공명 영상 방법 및 장치
KR101560463B1 (ko) 2013-12-30 2015-10-16 가천대학교 산학협력단 오프 공명 라디오주파수 펄스를 사용하는 자기 공명 영상 시스템에서 인공물 및 원하지 않는 신호를 제거하는 자기 공명 영상 획득 방법

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3544782B2 (ja) * 1996-04-16 2004-07-21 株式会社東芝 磁気共鳴診断装置
WO2003087864A1 (fr) * 2002-04-16 2003-10-23 Koninklijke Philips Electronics N.V. Imagerie par resonance magnetique multiecho a t1 pondere
JP2004261619A (ja) * 2004-06-25 2004-09-24 Toshiba Corp 磁気共鳴イメージング装置
WO2008042370A1 (fr) * 2006-10-03 2008-04-10 Duke University Systèmes et procédés permettant d'évaluer le transfert gazeux pulmonaire par irm avec du 129xe hyperpolarisé
WO2012151551A2 (fr) * 2011-05-04 2012-11-08 Oregon Health And Science University Méthode et appareil pour utiliser l'imagerie par résonance magnétique en vue de l'examen et du contrôle du cartilage

Also Published As

Publication number Publication date
KR20180130368A (ko) 2018-12-07
KR101949491B1 (ko) 2019-02-18

Similar Documents

Publication Publication Date Title
US10185013B2 (en) Magnetic resonance imaging (MRI) apparatus and method of generating MR image
CN113366330A (zh) 低场扩散加权磁共振成像
WO2014081095A1 (fr) Procédé et appareil pour capturer une image par résonance magnétique
WO2014051301A1 (fr) Appareil d'imagerie médicale et son procédé de commande
US20090274353A1 (en) Background magnetic resonance imaging
AU2015346431A1 (en) Pulse sequences for low field magnetic resonance
US10168405B2 (en) Method and apparatus for quantifying properties of an object through magnetic resonance imaging (MRI)
KR20170048558A (ko) 저 필드 자기 공명 이미징 시스템의 자동 구성
WO2013027964A1 (fr) Procédé et appareil de génération simultanée d'images de résonance magnétique de plusieurs types
EP3041418A1 (fr) Procédé pour corriger des erreurs associées à des décalages de synchronisation asynchrones entre la transmission et la réception d'horloges dans des bobines radiofréquence sans fil d'imagerie par résonance magnétique (irm)
US10444314B2 (en) Magnetic resonance imaging apparatus and method for acquiring under-sampled MR signal
JP2017511227A (ja) 改善された多相動的造影磁気共鳴撮像方法
EP3098619A2 (fr) Appareil et procédé pour l'imagerie parallèle par résonance magnétique nucléaire à trois dimensions avec un échantillonnage irrégulier de l'espace k
US9395430B2 (en) Method of generating magnetic resonance image, method of acquiring phase information of phase contrast image, method of acquiring phase information of susceptibility weighted image, and apparatus for generating magnetic resonance image
WO2013151349A1 (fr) Appareil d'imagerie par résonance magnétique capable d'acquérir une image sélective de matière grise et image par résonance magnétique l'utilisant
US9779485B2 (en) Magnetic resonance imaging apparatus and method
WO2016195281A1 (fr) Module de génération de champ magnétique à gradient utilisant une pluralité de bobines de façon à générer un champ magnétique à gradient
WO2018221831A1 (fr) Procédé de génération d'image par résonance magnétique et appareil d'imagerie par résonance magnétique associé
WO2018034543A1 (fr) Dispositif et procédé d'imagerie par résonance magnétique à transfert de saturation par échange chimique
WO2021215648A1 (fr) Appareil et procédé de génération d'image de résonance magnétique tridimensionnelle sélective en volume
WO2018221832A1 (fr) Procédé de génération d'image par résonance magnétique et appareil d'imagerie par résonance magnétique associé
CN117008029A (zh) 利用双空间饱和脉冲以补偿空间饱和带中的化学位移置换的系统和方法
US10488485B2 (en) Magnetic resonance imaging apparatus and method for obtaining magnetic resonance image
WO2018186578A1 (fr) Dispositif d'imagerie par résonance magnétique et son procédé de commande
WO2018093206A1 (fr) Dispositif d'imagerie par résonance magnétique à contraste amplifié et procédé

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 18810029

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 18810029

Country of ref document: EP

Kind code of ref document: A1