KR20190122315A - Image acquisition method and apparatus using parallel scheme of radio frequency irradiation and data acquisition - Google Patents

Abstract

Disclosed are a device and a method for obtaining an image using a paralleling technique of radiating a radio frequency and obtaining information. According to one embodiment of the present invention, the method for obtaining an image comprises the steps of: radiating a first radio frequency (RF) pulse signal to an object to saturate label protons; generating a proton signal by radiating a pulse sequence signal to the object; and acquiring a chemical exchange saturation transfer (CEST) image of the object from the proton signal. The steps of generating the proton signal and acquiring the CEST image are repeated in parallel.

Description

IMAGE ACQUISITION METHOD AND APPARATUS USING PARALLEL SCHEME OF RADIO FREQUENCY IRRADIATION AND DATA ACQUISITION}

The embodiments below relate to an image acquisition device and method for performing radio frequency radiation and information acquisition in parallel.

Magnetic Resonance Imaging (MRI) is a technique for acquiring anatomical tomography of humans. In general, since MRI acquires a signal from a proton of water constituting most of the human body, it is difficult to acquire protons of other substances having a relatively low distribution in the body as image information.

Chemical Exchange Saturation Transfer (CEST) MRI is a technology that enables the acquisition of image information of materials with low distribution, which are difficult to obtain from conventional MRI. In particular, it is an innovative technology for diagnosing a disease without a contrast agent because a signal distinct from normal tissue can be obtained from abnormal tissue such as cancer or tumor.

CEST MRI takes advantage of the phenomenon of chemical exchange between the protons of water and the protons of the target material. Radiation of radio frequency (RF) is saturated in the labile proton of the relatively small amount of target material, and saturated label protons are chemically exchanged with protons in unsaturated water to indirectly saturate water protons. Will be in a state.

By repeating this process, a large amount of protons in the water are gradually saturated, and after this process, images are obtained from the protons in the water.

In order to acquire a reference image, a general MRI image without the above-described preparation process is acquired, and the amount of label protons or environmental information is obtained by measuring the degree of saturation of the image of the CEST MRI to the reference image.

Conventional CEST MRI requires a long preparation process in which RF is repeatedly applied to label protons until the saturation of the water protons reaches steady-state before the image is acquired.

Furthermore, in order to obtain a high resolution or high signal-to-noise ratio (SNR) image, image information must be acquired several times. In this case, since the normal state of the proton saturation state is broken every time all the image information is acquired, a new preparation process is required, and thus, the entire photographing time becomes very long.

Embodiments may provide a technique for acquiring images at high speed by performing radio frequency radiation and information acquisition in parallel.

In addition, the embodiments may provide a technique for increasing the contrast of the CEST MRI image.

According to one or more exemplary embodiments, an image acquisition method includes saturating a label proton by radiating a first radio frequency (RF) pulse signal to an object, and generating a proton signal by radiating a pulse sequence signal to the object. And acquiring a chemical exchange saturation transfer (CEST) image of the object from the proton signal, wherein the generating and the acquiring are repeatedly performed in parallel.

The saturating step may include repeatedly radiating the first RF pulse signal until the label proton is saturated and reaches a steady-state.

The generating and acquiring may be performed to maintain the steady state while imposing the pulse sequence signal and the first RF pulse signal in parallel.

The pulse sequence signal may include a second RF pulse signal for obtaining a water proton signal and an inclination signal for generating the proton signal.

The sum of the slope signals may be a constant.

The inclination signal may include an x direction inclination signal, a y direction inclination signal, and a z direction inclination signal.

Gradient momentum of the x-direction gradient signal, the y-direction gradient signal, and the z-direction gradient signal may have the same value every time image information is acquired.

The pulse sequence signal may be a SSFP-FID (Steady State Free Precession Free Induction Decay) pulse sequence.

The acquiring may include dividing the proton signal into a reference signal, acquiring a label frequency corresponding to the label proton from the proton signal divided by the reference signal, and based on the frequency corresponding to the water proton. The method may include obtaining a symmetric proton signal with respect to a frequency symmetric with a frequency, and obtaining the CEST image by removing an MT effect by using a difference between the symmetric proton signal and the proton signal.

Obtaining the CEST image by removing the MT effect may include removing the MT effect based on the following equation.

[Equation]

Here, S _-f means the symmetric proton signal, S _{+ f} means the proton signal, S ₀ means the reference signal.

According to an embodiment, an image acquisition device may emit a first radio frequency (RF) pulse signal to an object to saturate a label proton, and emit a pulse sequence signal to the object to generate a proton signal. And an image generator for acquiring a chemical exchange saturation transfer (CEST) image of the object from the proton signal, wherein the generation of the proton signal and the acquisition of the image are repeatedly performed in parallel.

The signal generator may repeatedly emit the first RF pulse signal until the label proton is saturated and reaches a steady-state.

The signal generator and the image generator may maintain the steady state while imposing the pulse sequence signal and the first RF pulse signal in parallel.

The pulse sequence signal may include a second RF pulse signal for obtaining a water proton signal and an inclination signal for generating the proton signal.

The sum of the slope signals may be a constant.

The inclination signal may include an x direction inclination signal, a y direction inclination signal, and a z direction inclination signal.

Gradient momentum of the x-direction gradient signal, the y-direction gradient signal, and the z-direction gradient signal may have the same value every time image information is acquired.

The pulse sequence signal may be a SSFP-FID (Steady State Free Precession Free Induction Decay) pulse sequence.

The image generator divides the proton signal into a reference signal, obtains a label frequency corresponding to the label proton from the proton signal divided by the reference signal, and is symmetrical with the label frequency based on the frequency corresponding to the water proton. The CEST image may be obtained by acquiring a symmetric proton signal with respect to a frequency and removing an MT effect by using a difference between the symmetric proton signal and the proton signal.

The image generator may remove the MT effect based on the following equation.

 [Equation]

Here, S _-f means the symmetric proton signal, S _{+ f} means the proton signal, S ₀ means the reference signal.

1 is a schematic block diagram of an image capturing apparatus according to an exemplary embodiment.
2 illustrates an example of an operation of the image capturing apparatus illustrated in FIG. 1.
3 shows an example of a pulse sequence signal for image acquisition.
4 illustrates an example of an operation in which the image generator illustrated in FIG. 1 acquires an image.
FIG. 5A illustrates an example of a z-spectrum (or CEST spectrum) for comparing the performance of a conventional CEST MRI apparatus and the image capturing apparatus illustrated in FIG. 1.
FIG. 5B illustrates an example of an MTR asymmetric spectrum for comparing the performance of the conventional CEST MRI apparatus and the image capturing apparatus illustrated in FIG. 1.
6A illustrates an example of a CEST image obtained by a conventional CEST MRI apparatus.
6B illustrates an example of a CEST image obtained by the image capturing apparatus shown in FIG. 1.

Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. However, various changes may be made to the embodiments so that the scope of the patent application is not limited or limited by these embodiments. It is to be understood that all changes, equivalents, and substitutes for the embodiments are included in the scope of rights.

The terminology used herein is for the purpose of description and should not be construed as limiting. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "comprise" or "have" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described on the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Terms such as first or second may be used to describe various components, but the components should not be limited by the terms. The terms are for the purpose of distinguishing one component from another component only, for example, without departing from the scope of the rights according to the concepts of the embodiment, the first component may be named a second component, and similarly The second component may also be referred to as the first component.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art, and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

In addition, in the description with reference to the accompanying drawings, the same components regardless of reference numerals will be given the same reference numerals and duplicate description thereof will be omitted. In the following description of the embodiment, when it is determined that the detailed description of the related known technology may unnecessarily obscure the gist of the embodiment, the detailed description thereof will be omitted.

A module in the present specification may mean hardware capable of performing functions and operations according to each name described in the present specification, and may mean computer program code capable of performing specific functions and operations. Or an electronic recording medium, for example, a processor or a microprocessor, in which computer program code capable of performing specific functions and operations is mounted.

In other words, a module may mean a functional and / or structural combination of hardware for performing the technical idea of the present invention and / or software for driving the hardware.

1 is a schematic block diagram of an image capturing apparatus according to an exemplary embodiment.

Referring to FIG. 1, the image obtaining apparatus 10 may obtain a proton signal from an object by radiating an RF signal to the object. The image acquisition device 10 may acquire an image from the acquired proton signal.

An object means an object for which an image is to be acquired. For example, the object may include a human body.

The image acquisition apparatus 10 may acquire an image using a chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) method.

MRI may refer to a technique for acquiring an anatomical tomography image of a human. In general, MRI can acquire a signal from a proton of water that constitutes most of the human body. In the case of protons other than water, it may be difficult to obtain image information because of the relatively small amount present in the body.

CEST MRI signal can be obtained from the proton of a material with a small distribution difficult to obtain conventional MRI. CEST MRI can be used for accurate clinical diagnosis by directly acquiring proton signals of substances directly related to diseases such as tumors.

The image capturing apparatus 10 performs a process of radiating a radio frequency (RF) signal to a label proton in parallel with acquiring image information, so that label proton saturation is performed even during image acquisition. The steady-state of the state can be maintained throughout the shot.

The image capturing apparatus 10 does not need a new preparation process for saturation of the protons each time the image information is acquired, thereby greatly reducing the photographing time compared to the conventional CEST MRI method.

The image acquisition device 10 may provide a new CEST MRI method for performing RF radiation and image information acquisition in parallel. Since the image capturing apparatus 10 may maintain the normal state of the CEST mechanism and the image signal at the same time, the image capture device 10 may reduce the photographing speed by 5 times or more as compared to the conventional CEST MRI method, and may have an MR (which has better contrast) Magnetic Resonance) image can be provided.

The image acquisition apparatus 10 includes a signal generator 100 and an image generator 200.

The signal generator 100 may saturate a label proton by radiating a first radio frequency (RF) pulse signal to an object. The signal generator 100 may generate a proton signal by radiating a pulse sequence signal to the object.

The signal generator 100 may repeatedly emit the first RF pulse signal until the label protons saturate and reach a steady-state.

The image generator 200 may obtain a chemical exchange saturation transfer (CEST) image of the object from the proton signal. Generation of the proton signal and acquisition of the image may be performed in parallel and repeatedly.

The signal generator 100 and the image generator 200 may generate a proton signal and acquire an image while maintaining a steady state by using a pulse sequence signal. The signal generator 100 and the image generator 200 may maintain a normal state by imposing a pulse sequence signal and a first RF pulse signal in parallel.

The pulse sequence signal may include a second RF pulse signal for obtaining the water proton signal and a gradient signal for generating the proton signal. For example, the pulse sequence signal may be a Steady State Free Precession Free Induction Decay (SSFP-FID) pulse sequence.

The sum of the slope signals may be a constant. The inclination signal may include an x direction inclination signal, a y direction inclination signal, and a z direction inclination signal. The gradient momentum of the x-direction gradient signal, the y-direction gradient signal, and the z-direction gradient signal may have the same value every time image information is acquired.

2 illustrates an example of an operation of the image capturing apparatus illustrated in FIG. 1.

Referring to FIG. 2, the image capturing apparatus 10 may include a signal generator 100 and an image generator 200.

The signal generator 100 may generate an RF signal and an inclination signal to radiate to the object. The object may include a human body.

The signal generator 100 may include a main magnet capable of controlling a magnetic field. In addition, the signal generator 100 may include a transmitter. The transmitter may include an RF generator and a gradient signal generator.

The signal generator 100 may generate a pulse sequence signal. The signal generator 100 may radiate an RF pulse signal corresponding to the water protons to the object. The signal generator 100 may perform CEST preparation. The signal generator 100 may saturate the label protons using a gradient signal generator.

The image generator 200 may receive a proton signal from an object through a signal acquisition device included in a receiver. The image generator 200 may include a main processor. The main processor may generate a CEST image from the proton signal.

The main processor may output a control signal to the signal generator 100 to control the signal generator 100.

3 shows an example of a pulse sequence signal for image acquisition.

Referring to FIG. 3, the signal generator 100 may emit a first RF pulse signal to saturate the label protons. The first RF signal may be an RF signal corresponding to the label proton.

The signal generator 100 may repeatedly emit the first RF pulse signal until it saturates the label protons. For example, the signal generator 100 may repeatedly emit the first RF pulse signal 300 times.

The signal generator 100 may emit a pulse sequence signal for image acquisition. The pulse sequence signal may include an RF signal and a gradient signal corresponding to the water protons. For example, the pulse sequence signal may be a steady state free precession free induction decay (SSFD-FID) pulse sequence. The pulse sequence signal may include a second RF pulse signal and a gradient signal corresponding to the water protons.

When the image generator 200 acquires a signal of saturated water protons after applying a plurality of RF pulse signals, the image generator 200 may obtain a plurality of signals as much as possible to reduce the imaging time in the CEST MRI.

A spin echo or gradient echo sequence signal is obtained by applying an RF signal to a water proton, so that one signal is obtained from an MR signal. You may need to repeat the spinning N times.

Multi-echo imaging techniques, such as fast spin echo or echo planar imaging, apply an RF pulse signal to the water protons and then take those signals to obtain m signals. can do. In this case, since the radiation of 300 RF pulse signals need to be performed N / m times, the time can be shortened.

Techniques such as spin echo and gradient echo sequences provide high contrast but may have the disadvantage of taking too long an image acquisition time.

Even if the image acquisition time is solved by techniques such as fast spin echo or echo planar imaging, cancer acquisition CEST MRI, which requires high resolution and high signal-to-noise ratio (SNR), still has long image acquisition time, It can be difficult to apply.

In order to solve this problem, when the radiation of the RF pulse signal and the acquisition of the image information are performed in parallel, an image contrast may occur, which may make accurate diagnosis difficult.

The image capturing apparatus 10 may perform radiography of the RF pulse signal and acquisition of image information in parallel to provide a high contrast while providing a high contrast and accurately diagnose a disease such as cancer.

To this end, the signal generator 100 may not destroy the signal generated when the image is acquired. The signal generator 100 may use the signals continuously generated in a steady state and acquire them as one signal along with a new signal generated each time.

Since the proton signal of saturated water is not lost due to the image acquisition, it can return to the unsaturated state, and thus the specific gravity of water saturation due to the CEST effect may be higher. Therefore, the image generator 200 may provide an MR image having a higher contrast, thereby enabling accurate cancer diagnosis.

The image acquisition device 10 performs the operation of radiating an RF pulse signal (for example, a second pulse signal) to the label proton in parallel with the operation of acquiring image information, thereby saturating the label proton even during image acquisition. It is possible to maintain the steady state of the whole picture.

Therefore, the image capturing apparatus 10 does not need a new preparation process for the proton saturation state every time the image information is acquired, thereby greatly reducing the photographing time.

In the case of the conventional spoiled gradient echo (SPGR) method, an image signal generated once in water may be completely destroyed after image acquisition. Accordingly, the water signal may be partially saturated by the spoiled gradient echo while radiating the RF pulse signal for CEST.

Therefore, the ratio of water signal saturation due to the CEST effect in the acquired image may be reduced, which may make it difficult to diagnose a tumor or the like by worsening the contrast of the image.

The image acquisition apparatus 10 may use the image signal generated once for image acquisition to maintain a normal state without disappearing even after image acquisition. In this way, the image capturing apparatus 10 may increase the contrast of the image.

4 illustrates an example of an operation in which the image generator illustrated in FIG. 1 acquires an image.

Referring to FIG. 4, the image generator 200 may use a continuous chemical exchange phenomenon between a proton of water and an unstable proton (label proton) of another material. The protons of the water and the label protons can generally have different frequencies in the main magnetic field of the MRI.

When the signal generator 100 emits and saturates an RF pulse signal (e.g., a first pulse signal) corresponding to the label proton's frequency, the saturated label proton chemically exchanges with the proton of unsaturated water to indirectly proton the water. May become saturated. The signal generator 100 may perform this process repeatedly to gradually saturate a large amount of protons in the water with a small amount of label protons.

The image generator 200 may acquire an image S _f (or a proton signal) from the protons of the water when the saturation state changes of the protons of the water and the label protons become steady-state. In addition, the image generator 200 may acquire a general MRI image (S ₀ ) (or a reference signal) having no saturation process, and measure how saturated the images of the CEST MRI are compared to the general image to obtain information on the label protons. have.

That is, the image generator 200 may divide the proton signal into a reference signal. This may be represented as in Equation 1.

In the example of FIG. 4, S _f may correspond to S _sat .

The image generator 200 may saturate protons of other polymer materials in the frequency domain of the specific material with the emitted first RF pulse signal to saturate the label protons of the particular material.

Protons of the polymer material saturated with the first RF pulse signal may also saturate the protons of water through MT (Magnetization Transfer) phenomenon, making it difficult to accurately measure the CEST effect of the specific material to be measured relatively. In order to solve this problem, the image generator 200 may remove the effect of saturation of the protons of water due to the MT phenomenon.

In general, the material causing the MT phenomenon can be distributed over a very wide frequency band. If the frequency of the water proton is set to 0 ppm, the frequency of the polymer material causing the MT effect based on 0 ppm may exist symmetrically.

The image generator 200 obtains a label frequency corresponding to the label proton from the proton signal divided by the reference signal, and obtains a symmetric proton signal with respect to a frequency symmetrical with the label frequency based on the frequency corresponding to the water proton. Can be.

Accordingly, the image generator 200 obtains the CEST image (or proton signal) once at the frequency (or label frequency) of a specific material to remove the MT effect, and the CEST image (at the opposite frequency with respect to the proton of water (0 ppm)). Alternatively, after obtaining a symmetric proton signal, two images may be subtracted to remove the MT effect and obtain an image in which only the CEST effect remains.

That is, the image generator 200 may acquire the CEST image by removing the MT effect by using the difference between the symmetric proton signal and the proton signal. For example, the image generator 200 may remove the MT effect based on Equation 2.

Here, S- _f may mean a symmetric proton signal, S _{+ f} may mean a proton signal, and S ₀ may mean a reference signal.

Specifically, S _{+ f} refers to the acquired image by emitting an RF pulse signal having a frequency corresponding to the label of a particular substance to be measured, and the proton, _-f S by emitting an RF pulse signal having a frequency other side relative to the water It may mean an acquired image.

S ₀ is a reference image and may mean a general MRI image without applying an RF pulse signal for saturation. The image generator 200 may obtain a signal having only the CEST effect through Equation 2.

4A may indicate that chemical exchange takes place between a specific substance (solute proton or label proton) and a proton of water. In FIG. 4B, the left graph may indicate a relative distribution of protons according to frequency bands.

It can be seen that the intensity of the signal is greatest at 4.75ppm, which is the frequency of the water proton which occupies the most amount. In FIG. 4B, the graph to the right may indicate that the signal generator 100 applies an RF pulse signal at 8.25 ppm to saturate a specific material, thereby decreasing the intensity of the proton of 4.75 ppm of water.

4c may represent a graph of a value obtained by dividing the proton signal by the reference signal using Equation 1. When the signal generator 100 emits radiation while changing the frequency of the RF pulse signal for saturation of a specific material, the image generator 200 acquires S _f (or S _sat ), and uses the general MRI image S ₀ as a reference. It can be divided as shown in c of FIG.

Based on the frequency of the water protons, there may be water protons at 0 ppm. When the signal generator 100 applies an RF pulse signal for saturation at 0 ppm, the proton of water is directly saturated, so it can be seen that the ratio of the signal appears the least.

Since there is a proton of a specific substance to be measured at 3.5 ppm from 0 ppm, if the signal generator 100 applies an RF pulse signal for saturation at 3.5 ppm, the signal intensity from the proton of water may be reduced by chemical exchange. . 4, d may represent a result measured using Equation 2. FIG. The image generator 200 may remove the MT effect through Equation 2 and obtain an image indicating only the effect of the CEST at 3.5 ppm.

FIG. 5A illustrates an example of a z-spectrum (or CEST spectrum) for comparing the performance of the conventional CEST MRI apparatus and the image capturing apparatus illustrated in FIG. 1, and FIG. 5B is a diagram illustrating an existing CEST MRI apparatus and FIG. An example of an MTR asymmetric spectrum for comparing the performance of the illustrated image capturing apparatus is shown, FIG. 6A illustrates an example of a CEST image acquired by a conventional CEST MRI apparatus, and FIG. 6B is an image acquisition illustrated in FIG. An example of the CEST image acquired by the device is shown.

5A to 6B, the performance of the conventional CEST MRI method and the image capturing apparatus 10 may be compared. A creatine phantom with amine protons (1.9 ppm) was used for performance comparison. In order to accurately compare only the effects of SSFP-FID and spoiled gradient echo (SPGR), the parameters used in the experiment were set identical in all experiments.

The parameters used in the experiment can be shown in Table 1.

Parameter type Parameter value Repetition Time (TR) / Echo Time (TE) 19 / 1.7 ms RF flip angle for CEST effect 220 degree RF duration for CEST effect 15.7 ms (bandwidth: 1 ppm at 3T MRI) RF flip angle for image acquisition 10 degree Matrix size 160 ×× 160 Field-of-view 160 ×× 160 mm ²

As shown in the comparison result, it can be seen that the image acquisition device 10 using the SSFP-FID has about 25% higher intensity than the SPGR method. In addition, it can be seen that the image acquisition device 10 provides a higher contrast than the existing SPGR method.

Therefore, the image capturing apparatus 10 may enable a more accurate diagnosis than the conventional SPGR method, and the imaging time may be about 8 compared to the conventional methods such as spin echo, gradient echo sequence, fast spin echo, and echo flanna imaging. It can be shortened by about twice.

The method according to the embodiment may be embodied in the form of program instructions that can be executed by various computer means and recorded in a computer readable medium. Computer-readable media may include, alone or in combination with the program instructions, data files, data structures, and the like. The program instructions recorded on the media may be those specially designed and constructed for the purposes of the embodiments, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

The software may include a computer program, code, instructions, or a combination of one or more of the above, and configure the processing device to operate as desired, or process independently or collectively. You can command the device. Software and / or data may be any type of machine, component, physical device, virtual equipment, computer storage medium or device in order to be interpreted by or to provide instructions or data to the processing device. Or may be permanently or temporarily embodied in a signal wave to be transmitted. The software may be distributed over networked computer systems so that they may be stored or executed in a distributed manner. Software and data may be stored on one or more computer readable recording media.

Although the embodiments have been described with reference to the accompanying drawings as described above, those skilled in the art may apply various technical modifications and variations based on the above. For example, the described techniques may be performed in a different order than the described method, and / or components of the described systems, structures, devices, circuits, etc. may be combined or combined in a different form than the described method, or other components Or even if replaced or substituted by equivalents, an appropriate result can be achieved.

Therefore, other implementations, other embodiments, and equivalents to the claims are within the scope of the following claims.

Claims (20)

Saturating a label proton by radiating a first Radio Frequency (RF) pulse signal to the object;
Generating a proton signal by radiating a pulse sequence signal to the object;
Acquiring a chemical exchange saturation transfer (CEST) image of the object from the proton signal
Including,
The generating and acquiring are repeatedly performed in parallel
Image Acquisition Method.
The method of claim 1,
The saturation step,
Repeatedly radiating the first RF pulse signal until the label proton is saturated and reaches a steady-state
Image acquisition method comprising a.
The method of claim 2,
The generating step and the obtaining step,
Is performed to maintain the steady state while imposing the pulse sequence signal and the first RF pulse signal in parallel
Image Acquisition Method
The method of claim 1,
The pulse sequence signal,
A second RF pulse signal for obtaining a water proton signal and a slope signal for generating the proton signal
Image Acquisition Method.
The method of claim 4, wherein
The sum of the slope signals is a constant
Image Acquisition Method.
The method of claim 4, wherein
The inclination signal is,
including an x direction inclination signal, a y direction inclination signal and a z direction inclination signal
Image Acquisition Method.
The method of claim 6,
Gradient momentum of the x-direction tilt signal, the y-direction tilt signal, and the z-direction tilt signal has the same value every time the image information is acquired.
Image Acquisition Method.
The method of claim 4, wherein
The pulse sequence signal,
SSFP-FID (Steady State Free Precession Free Induction Decay) pulse sequence
Image Acquisition Method.
The method of claim 1,
The obtaining step,
Dividing the proton signal into a reference signal;
Obtaining a label frequency corresponding to the label proton from the proton signal divided by a reference signal;
Acquiring a symmetric proton signal at a frequency symmetrical with the label frequency based on a frequency corresponding to a water proton
Acquiring the CEST image by removing an MT effect by using a difference between the symmetric proton signal and the proton signal
Image acquisition method comprising a.
The method of claim 9,
Obtaining the CEST image by removing the MT effect,
Removing the MT effect based on the following equation
Image acquisition method comprising a.
[Equation]

Here, S _-f means the symmetric proton signal, S _{+ f} means the proton signal, S ₀ means the reference signal.
A signal generator that emits a first radio frequency (RF) pulse signal to an object to saturate a label proton and radiates a pulse sequence signal to the object to generate a proton signal; And
An image generator for acquiring a chemical exchange saturation transfer (CEST) image of the object from the proton signal
Including,
The generation of the proton signal and the acquisition of the image are repeatedly performed in parallel
Image Acquisition Device.
The method of claim 11,
The signal generator,
Repeatedly radiating the first RF pulse signal until the label proton is saturated and reaches a steady-state
Image Acquisition Device.
The method of claim 12,
The signal generator and the image generator,
Maintaining the steady state while imposing the pulse sequence signal and the first RF pulse in parallel
Image Acquisition Method
The method of claim 11,
The pulse sequence signal,
A second RF pulse signal for obtaining a water proton signal and a slope signal for generating the proton signal
Image Acquisition Device.
The method of claim 14,
The sum of the slope signals is a constant
Image Acquisition Device.
The method of claim 14,
The inclination signal is,
including an x direction inclination signal, a y direction inclination signal and a z direction inclination signal
Image Acquisition Device.
The method of claim 16,
Gradient momentum of the x-direction tilt signal, the y-direction tilt signal, and the z-direction tilt signal has the same value every time the image information is acquired.
Image Acquisition Device.
The method of claim 17,
The pulse sequence signal,
SSFP-FID (Steady State Free Precession Free Induction Decay) pulse sequence
Image Acquisition Device.
The method of claim 1,
The image generator,
The proton signal is divided by a reference signal, a label frequency corresponding to the label proton is obtained from the proton signal divided by the reference signal, and symmetric protons with respect to a frequency symmetrical with the label frequency based on the frequency corresponding to the water proton. Acquiring the signal and removing the MT effect by using the difference between the symmetric proton signal and the proton signal to acquire the CEST image.
Image Acquisition Device.
The method of claim 19,
The image generator,
Removing the MT effect based on the following equation
Image Acquisition Device.
[Equation]

Here, S _-f means the symmetric proton signal, S _{+ f} means the proton signal, S ₀ means the reference signal.

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