KR102105756B1 - Image acquisition method and apparatus using parallel scheme of radio frequency irradiation and data acquisition - Google Patents

Abstract

Disclosed is an image acquisition apparatus and method using a parallel technique of radio frequency radiation and information acquisition. An image acquisition method according to an embodiment 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 obtaining a CEST (Chemical Exchange Saturation Transfer) image for the object from the proton signal, wherein the generating step and the acquiring step are performed repeatedly in parallel.

Description

Image acquisition device and method using parallel technique of radio frequency radiation and information acquisition {IMAGE ACQUISITION METHOD AND APPARATUS USING PARALLEL SCHEME OF RADIO FREQUENCY IRRADIATION AND DATA ACQUISITION}

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

Magnetic Resonance Imaging (MRI) is a technique for acquiring anatomical tomography of a person. In general, since MRI acquires signals from protons of water constituting most of the human body, it is difficult to obtain protons of other substances that are relatively small in the body as image information.

Chemical exchange saturation transfer (CEST) MRI is a technology that can acquire image information of materials with low distribution that are difficult to obtain by conventional MRI. In particular, it is an innovative technology that can diagnose a disease without a contrast agent because it can acquire signals distinct from normal tissues in abnormal tissues such as cancer or tumor.

CEST MRI uses the phenomenon of chemical exchange between the proton of water and the proton of the target substance. It radiates and saturates by radiating radio frequency (RF) to the proton (labile proton) of the relatively small target substance, and indirectly saturates the proton of water by chemically exchanging it with the proton of unsaturated water. State.

By repeatedly performing this process, a large amount of protons in water is gradually saturated, and after this process, an image is acquired from the protons of water.

In order to obtain a reference image, a general MRI image without the above-described preparation process is acquired, and the degree of saturation of the CEST MRI image with respect to the reference image is measured to obtain the amount of label protons or environmental information.

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

Moreover, in order to acquire a high resolution or high signal-to-noise ratio (SNR) image, it is necessary to acquire image information several times. At this time, a new preparation process is required because the normal state of the proton saturation state is broken every time all the image information is acquired, and thus the entire shooting time is very long.
As a prior document on a magnetic resonance imaging device, there is Korean Patent Registration No. 10-0610990.

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

In addition, the embodiments can provide a technique to increase the contrast of the CEST MRI image.

An image acquisition method according to an embodiment 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 obtaining a CEST (Chemical Exchange Saturation Transfer) image for the object from the proton signal, wherein the generating step and the acquiring step are performed repeatedly 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 step and the acquiring step may be performed to maintain the steady state while charging 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 a slope signal for generating the proton signal.

The sum of the slope signals may be constant.

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

The gradient momentum of the inclination signal in the x direction, the inclination signal in the y direction, and the inclination signal in the z direction 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 step includes: dividing the proton signal into a reference signal; obtaining a label frequency corresponding to the label proton from the proton signal divided into a reference signal; and the label based on the frequency corresponding to the water proton. The method may include acquiring a symmetric proton signal with respect to a frequency that is symmetric with a frequency, and acquiring the CEST image by removing an MT effect by using a difference between the symmetric proton signal and the proton signal.

The step of acquiring the CEST image by removing the MT effect may include removing the MT effect based on the following equation.

[Mathematics]

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

The image acquiring apparatus according to an embodiment generates a proton signal by saturating a label proton by radiating a first radio frequency (RF) pulse signal to an object, and emitting a pulse sequence signal to the object. And an image generator for acquiring a chemical exchange saturation transfer (CEST) image for the object from the proton signal, and generating the proton signal and acquiring the image are performed repeatedly 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 charging 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 a slope signal for generating the proton signal.

The sum of the slope signals may be constant.

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

The gradient momentum of the inclination signal in the x direction, the inclination signal in the y direction, and the inclination signal in the z direction 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 a proton signal divided into a reference signal, and is symmetric with the label frequency based on the frequency corresponding to the water proton. The CEST image can 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.

 [Mathematics]

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

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

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

The terms used in the examples are for illustrative purposes only and should not be construed as limiting. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “include” or “have” are intended to indicate that a feature, number, step, operation, component, part, or combination thereof described on the specification exists, and that one or more other features are present. It should be understood that the existence or addition possibilities of fields or numbers, steps, operations, components, parts or combinations thereof are not excluded in advance.

The terms 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, for example, without departing from the scope of rights according to the concept of the embodiment, the first component may be referred to as the 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 a person skilled in the art to which the embodiment belongs. Terms such as those defined in a commonly used dictionary should be interpreted as having meanings consistent with meanings in the context of related technologies, and should not be interpreted as ideal or excessively formal meanings unless explicitly defined in the present application. Does not.

In addition, in the description with reference to the accompanying drawings, the same reference numerals are assigned to the same components regardless of reference numerals, and redundant descriptions thereof will be omitted. In describing the embodiments, when it is determined that detailed descriptions of related known technologies may unnecessarily obscure the subject matter of the embodiments, detailed descriptions 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, or computer program code capable of performing specific functions and operations. Or, it may mean an electronic recording medium on which computer program code capable of performing a specific function and operation is mounted, for example, a processor or a microprocessor.

In other words, the 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 acquisition device according to an embodiment.

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

Object means an object to acquire an image. For example, the object may include the human body.

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

MRI may refer to a technique of acquiring a human anatomical tomography image. In general, MRI can acquire signals from the protons of water that make up most of the human body. In the case of protons of substances other than water, it may be difficult to acquire image information because the amount of the substance present in the body is relatively small.

CEST MRI can be acquired by signals from protons of substances with little distribution that are difficult to obtain by conventional MRI. CEST MRI can be used for accurate clinical diagnosis because it can directly acquire proton signals of substances directly related to diseases such as tumors.

The image acquisition device 10 performs a task of radiating a radio frequency (RF) signal to a label proton (labile proton) and a task of acquiring image information in parallel, thereby saturating the label proton even while acquiring an image. The steady-state of the state can be maintained throughout shooting.

The image acquiring device 10 does not require a new preparation process for the proton saturation when acquiring image information each time, and thus can significantly shorten the shooting 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 in parallel. Since the image acquisition device 10 can simultaneously maintain the normal state of the CEST mechanism and the image signal, it is possible to shorten the shooting speed by 5 times or more compared to the conventional CEST MRI method, and MR (MR) having better contrast Magnetic Resonance) video.

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

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

The signal generator 100 may repeatedly emit the first RF pulse signal until the label proton is saturated and reaches 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 a proton signal and acquisition of an image may be performed repeatedly in parallel.

The signal generator 100 and the image generator 200 may generate a proton signal and acquire an image while maintaining a steady state using a pulse sequence signal. The signal generator 100 and the image generator 200 may maintain a steady state while charging 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 a gradient signal for generating a proton signal. For example, the pulse sequence signal may be a SSFP-FID (Steady State Free Precession Free Induction Decay) pulse sequence.

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

FIG. 2 shows an example of the operation of the image acquisition device illustrated in FIG. 1.

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

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

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

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

The image generator 200 may receive a proton signal from an object through a signal acquisition device included in the receiver. The image generator 200 may include a main processor. The main processor can generate a CEST image from a 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 proton. The first RF signal may be an RF signal corresponding to the label proton.

The signal generator 100 may emit the first RF pulse signal repeatedly until the label proton is saturated. For example, the signal generator 100 may emit the first RF pulse signal 300 times repeatedly.

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

When the image generator 200 acquires a signal of a saturated water proton after applying a plurality of RF pulse signals, it is possible to obtain as many signals as possible to reduce the shooting time in the CEST MRI.

Since the spin echo or gradient echo sequence signal acquires a single signal as an MR signal generated by applying an RF signal to a water proton, if an image is composed of N signals, 300 RF pulse signals are generated. The radiation may need to be repeated N times.

When using multi-echo imaging techniques such as fast spin echo or echo planar imaging, RF signals are applied to water protons, and then m signals are obtained by utilizing the signals. can do. In this case, since the emission of 300 RF pulse signals can be performed N / m times, time can be shortened.

Techniques such as spin echo and oblique echo sequence provide high contrast, but may have the disadvantage that the image acquisition time is too long.

Even if the image acquisition time is solved by technologies such as fast spin echo or eco-planar imaging, the CEST MRI for cancer diagnosis that requires high resolution and high signal-to-noise ratio (SNR) still has a long image acquisition time, and in actual clinical practice It can be difficult to apply.

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

The image acquisition device 10 may perform radiation of the RF pulse signal and acquisition of image information in parallel to provide a high contrast and provide high contrast compared to existing technologies to accurately diagnose diseases such as cancer.

To this end, the signal generator 100 may not extinguish the signal generated when the image is acquired. The signal generator 100 may use continuously generated signals in a normal state, and acquire them as a single signal together with a new signal that occurs each time.

Since the proton signal of saturated water does not disappear due to image acquisition, the specific gravity of water saturation by the CEST effect may be higher because it can return to the unsaturated state again. 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 a task of emitting an RF pulse signal (for example, a second pulse signal) to a label proton and a task of acquiring image information in parallel, thereby saturating the label proton even while acquiring an image. Can maintain the steady state throughout the shooting.

Therefore, the image acquisition device 10 can greatly shorten the shooting time because a new preparation process for proton saturation is not required each time image information is acquired.

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

Therefore, the water signal saturation ratio due to the CEST effect in the acquired image may be reduced, which may worsen the contrast of the image and make it difficult to diagnose tumors and the like.

The image acquisition device 10 may be used to maintain a normal state without destroying an image signal generated once for image acquisition even after image acquisition. Through this, the image acquisition device 10 may increase the contrast of the image.

4 shows 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 utilize a continuous chemical exchange phenomenon between a water proton and an unstable proton (label proton) of another material. Water protons and label protons can generally have different frequencies in the MRI main magnetic field.

When the signal generator 100 emits and saturates by radiating an RF pulse signal (for example, a first pulse signal) that matches the frequency of the label proton, the saturated label proton chemically exchanges with the proton of unsaturated water to indirectly proton the water. Can be saturated. The signal generator 100 may perform this process repeatedly to gradually saturate a large amount of protons in water with a small amount of label protons.

At this time, the image generator 200 may acquire an image S _f (or proton signal) from the proton of water when the change in the saturation state of the proton and the label proton of the water becomes a steady-state. In addition, the image generator 200 may obtain a general MRI image (S ₀ ) (or a reference signal) having no saturation process, and measure how saturated the CEST MRI image is compared to the general image to obtain label proton information. have.

That is, the image generator 200 may divide the proton signal into a reference signal. This can be expressed as Equation (1).

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

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

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

In general, substances that cause MT phenomena can be distributed over a very wide frequency band. When 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 be symmetrically present.

The image generator 200 obtains a label frequency corresponding to a label proton from a proton signal divided into a reference signal, and acquires a symmetric proton signal with respect to a frequency symmetric with the label frequency based on a frequency corresponding to a water proton. You can.

Therefore, the image generator 200 obtains a CEST image (or proton signal) once at a frequency (or label frequency) of a specific substance in order to remove the MT effect, and a CEST image at a frequency opposite the proton of water (0 ppm). Alternatively, after obtaining a symmetric proton signal), the MT effect is removed by subtracting the two images, and only the CEST effect remains.

That is, the image generator 200 may obtain the CEST image by removing the MT effect 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 symmetrical proton signal, S _{+ f} may mean a proton signal, and S ₀ may mean a reference signal.

Specifically, S _{+ f} means an image obtained by radiating an RF pulse signal having a frequency corresponding to a label proton of a specific substance to be measured, and S _-f radiates an RF pulse signal having an opposite frequency based on water. It may mean the acquired image.

S ₀ is a reference image and may mean a general MRI image to which an RF pulse signal for saturation is not applied. Through Equation 2, the image generator 200 may acquire a signal having only a CEST effect.

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

It can be seen that the signal intensity is highest at 4.75ppm, which is the frequency of the water proton, which occupies the largest amount. The graph on the right in b of FIG. 4 may indicate that the signal generator 100 applies an RF pulse signal to 8.25 ppm to saturate a specific material, thereby reducing the intensity of the proton of water of 4.75 ppm.

4C can represent a graph for a value obtained by dividing a proton signal by a reference signal using Equation (1). When the signal generator 100 emits 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 it becomes a standard MRI image S ₀ as a reference. It can be divided and expressed as c in FIG. 4.

When considered based on the frequency of water protons, water protons may be present at 0 ppm. When the signal generator 100 applies an RF pulse signal for saturation to 0 ppm, it can be seen that the proton of water is directly saturated, so that the ratio of the signal is the lowest.

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

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

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

Table 1 shows parameters used in the experiment.

Parameter type Parameter value TR (Repetition Time) / TE (Echo Time) 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 (FOV) 160 ×× 160 mm ²

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

Therefore, the image acquisition device 10 may enable a more accurate diagnosis compared to the conventional SPGR method, and the shooting time is about 8 compared to the conventional spin echo, oblique echo sequence, fast spin echo and echo planar imaging methods. You can shorten it about twice as much.

The method according to the embodiment may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer readable medium. Computer-readable media may include program instructions, data files, data structures, or the like alone or in combination. The program instructions recorded on the medium may be specially designed and constructed for the embodiments or may be known and usable by those skilled in computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CD-ROMs, DVDs, and magnetic media such as floptical disks. -Hardware devices specially configured to store and execute program instructions such as magneto-optical media, and ROM, RAM, flash memory, and the like. Examples of program instructions include high-level language code that can be executed by a computer using an interpreter, etc., as well as machine language codes produced by a compiler. 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, instruction, or a combination of one or more of these, 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 interpreted by a processing device, or to provide instructions or data to a processing device, of any type of machine, component, physical device, virtual equipment, computer storage medium or device. , Or may be permanently or temporarily embodied in the transmitted signal wave. The software may be distributed on networked computer systems, and stored or executed in a distributed manner. Software and data may be stored in one or more computer-readable recording media.

As described above, although the embodiments have been described with limited drawings, those skilled in the art can apply various technical modifications and variations based on the above. For example, the described techniques are performed in a different order than the described method, and / or the components of the described system, structure, device, circuit, etc. are combined or combined in a different form from the described method, or other components Alternatively, even if replaced or substituted by equivalents, appropriate results can be achieved.

Therefore, other implementations, other embodiments, and equivalents to the claims are also 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 emitting a pulse sequence signal to the object;
Obtaining a CEST (Chemical Exchange Saturation Transfer) image for the object from the proton signal
Including,
The generating step and the acquiring step are performed repeatedly in parallel.
Image acquisition method.
According to claim 1,
The saturating step,
Repeatedly emitting the first RF pulse signal until the label proton is saturated and reaches a steady-state
Image acquisition method comprising a.
According to claim 2,
The generating step and the obtaining step,
It is performed to maintain the steady state while charging the pulse sequence signal and the first RF pulse signal in parallel.
Image acquisition method
According to 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.
According to claim 4,
The sum of the slope signals is constant
Image acquisition method.
According to claim 4,
The slope signal,
including an inclined signal in the x direction, an inclined signal in the y direction, and an inclined signal in the z direction.
Image acquisition method.
The method of claim 6,
The gradient momentum of the x-direction slope signal, the y-direction slope signal, and the z-direction slope signal has the same value every time image information is acquired.
Image acquisition method.
The method of claim 4,
The pulse sequence signal,
SSFP-FID (Steady State Free Precession Free Induction Decay) pulse sequence
Image acquisition method.
According to claim 1,
The obtaining step,
Dividing the proton signal into a reference signal;
Obtaining a label frequency corresponding to the label proton from a proton signal divided by a reference signal;
Obtaining a symmetric proton signal with respect to a frequency symmetric with the label frequency based on a frequency corresponding to a water proton
Obtaining the CEST image by removing the MT effect using the difference between the symmetric proton signal and the proton signal
Image acquisition method comprising a.
The method of claim 9,
The step of acquiring the CEST image by removing the MT effect,
Removing the MT effect based on the following equation
Image acquisition method comprising a.
[Mathematics]

Here, S _-f means the symmetric proton signal, S _{+ f} means the proton signal, and S ₀ means the reference signal.
A signal generator emitting a first radio frequency (RF) pulse signal to an object to saturate a label proton, and emitting a pulse sequence signal to the object to generate a proton signal; And
An image generator that acquires a Chemical Exchange Saturation Transfer (CEST) image for the object from the proton signal
Including,
Generation of the proton signal and acquisition of the image are performed repeatedly in parallel.
Image acquisition device.
The method of claim 11,
The signal generator,
Repeatedly emitting 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 charging the pulse sequence signal and the first RF pulse in parallel
Image acquisition device.
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 constant
Image acquisition device.
The method of claim 14,
The slope signal,
including an inclined signal in the x direction, an inclined signal in the y direction, and an inclined signal in the z direction.
Image acquisition device.
The method of claim 16,
The gradient momentum of the x-direction slope signal, the y-direction slope signal, and the z-direction slope signal has the same value every time 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 11,
The image generator,
Divide the proton signal into a reference signal, obtain a label frequency corresponding to the label proton from the proton signal divided into a reference signal, and symmetric proton with respect to a frequency symmetric with the label frequency based on the frequency corresponding to the water proton Acquiring the signal, and obtaining the CEST image by removing the MT effect using the difference between the symmetric proton signal and the proton signal
Image acquisition device.
The method of claim 19,
The image generator,
Eliminating the MT effect based on the following equation
Image acquisition device.
[Mathematics]

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

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