KR101623129B1 - Method of obtaining bio-image using resonance of magnetic nano particle - Google Patents

Method of obtaining bio-image using resonance of magnetic nano particle Download PDF

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Publication number
KR101623129B1
KR101623129B1 KR1020150090506A KR20150090506A KR101623129B1 KR 101623129 B1 KR101623129 B1 KR 101623129B1 KR 1020150090506 A KR1020150090506 A KR 1020150090506A KR 20150090506 A KR20150090506 A KR 20150090506A KR 101623129 B1 KR101623129 B1 KR 101623129B1
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magnetic
magnetic field
magnetic nanoparticles
nanoparticles
image
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KR1020150090506A
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Korean (ko)
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김상국
이재혁
유명우
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서울대학교 산학협력단
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Priority to PCT/KR2016/006729 priority patent/WO2016209012A2/en

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    • 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
    • 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

Abstract

The present invention relates to a method for obtaining a bio-image. The method for obtaining a bio-image according to the present invention comprises the steps of: (a) providing a magnetic nano-particle (100) having a magnetic vortex structure (110); (b) applying the first magnetic field to the magnetic nano-particle (100) so that the magnetic nano-particle (100) can have a resonance frequency; (c) applying the second magnetic field having a resonance frequency to the magnetic nano-particle (100); (d) releasing an application of the second magnetic field; (e) measuring time T1V consumed for a z-axis magnetic component of the magnetic nano-particle (100) to be restored to a predetermined ratio, or time T2V consumed for an x-axis or y-axis magnetic component of the magnetic nano-particle (100) to be reduced to a predetermined ratio; and (f) obtaining an image signal from at least one of the T1V or T2V. The present invention is designed to provide a method for obtaining a bio-image capable of obtaining an image of human beings by applying low magnetic field as compared to a conventional apparatus for obtaining an MR image. In addition, the present invention is designed to provide a method for obtaining a bio-image with higher signal sensitivity than a magnetic resonance image that can be filmed quickly.

Description

METHOD OF OBTAINING BIO-IMAGE USING RESONANCE OF MAGNETIC NANO PARTICLE USING RESONANCE OF MAGNETIC NANOPARTICLES [0002]

The present invention relates to a bio-image acquisition method. More specifically, the time required for recovering the Z-axis magnetization component of the magnetic nanoparticles having the magnetic vortex structure to a predetermined ratio or the time taken for the X- or Y-axis magnetization component of the magnetic nanoparticles to decrease to a predetermined ratio is measured And obtaining a magnetic vortex resonance image (Magnetic Vortex Resonance Imaging).

The medical imaging apparatus provides information on the patient's body as an image, and typically includes a magnetic resonance imaging apparatus, an X-ray apparatus, and an ultrasonic diagnostic apparatus. Of these, MRI (Magnetic Resonance Imaging) devices can capture soft tissues such as muscles, ligaments, and cranial nerves at high resolution without using radiation and provide many diagnostic information. Lt; / RTI >

Magnetic resonance imaging (MRI) uses a principle of applying a constant magnetic field to an atomic nucleus and supplying a constant frequency and energy to convert the energy emitted from the atomic nucleus into a signal to diagnose the inside of the human body. The nucleus, especially the protons that constitute the hydrogen nucleus in water, have spin angular momentum and magnetic dipoles by themselves, so if they apply a magnetic field, they align in the direction of the magnetic field, and the nucleus carries out the motion around the direction of the magnetic field. Such a car wash motion can acquire a human body image through nuclear magnetic resonance phenomenon.

However, since a magnetic resonance imaging apparatus uses a device including a superconducting magnet capable of applying a high magnetic field of about 1-11T, energy consumption is high and equipment is expensive. In addition, since the magnetization fraction is very small and the signal sensitivity is very low, there is a problem that a long time of 30 minutes or more is consumed.

In order to acquire the magnetic resonance image more clearly, a method of increasing the image contrast by injecting the contrast agent from the outside has been proposed. The relaxation time at which the nuclear spin of the water molecule returns to equilibrium is different for each tissue. The contrast agent can sharpen the image of the MRI by spreading the difference in tissue relaxation time.

However, a contrast agent exhibiting high water solubility and high magnetic relaxation in combination with water is rare. Further, the contrast agent has a high magnetic loss due to thermal fluctuation and has a relatively high cytotoxicity in vivo.

It is an object of the present invention to solve all the problems described above.

An object of the present invention is to provide a bio-image acquiring method capable of acquiring an image of a human body by applying a magnetic field compared to a conventional magnetic resonance imaging apparatus.

It is another object of the present invention to provide a bio-image acquisition method capable of taking a picture with a higher signal sensitivity than a magnetic resonance image.

According to one aspect of the present invention, there is provided a magnetic nanoparticle comprising: (a) providing magnetic nanoparticles having a magnetic vortex structure; (b) applying a first magnetic field to the magnetic nanoparticles so that the magnetic nanoparticles have a resonant frequency; (c) applying a second magnetic field having the resonant frequency to the magnetic nanoparticles; (d) canceling the application of the second magnetic field; (e) measuring a time T1v required for recovering the Z-axis magnetization component of the magnetic nanoparticles to a predetermined ratio, or a time T2v required for decreasing the X-axis or Y-axis magnetization component of the magnetic nanoparticles to a predetermined ratio; And (f) acquiring a video signal from at least one of the T1v and the T2v.

The T1v may be the longitudinal axis relaxation time of the magnetic nanoparticles in the body tissue.

The T2v may be the transverse axis relaxation time of the magnetic nanoparticles in the body tissue.

The T2v may be a value obtained by adding a free induction decay to the transverse axis relaxation time.

The predetermined ratio may be 63%.

T1v and T2v may have predetermined values depending on the material, size, intensity of the first magnetic field, and surrounding body tissue of the magnetic nanoparticles.

The T1V or T2V of the plurality of magnetic nanoparticles may be contrasted with a predetermined value to obtain an image signal of the body tissue in which the magnetic nanoparticles are located.

The step (f) includes the steps of: (f1) applying a predetermined magnetic field pulse to the magnetic nanoparticles at the time T1V or T2V; And (f2) acquiring an image signal of a bodily tissue in which the magnetic nanoparticles are positioned through a response to the magnetic field pulse.

The first magnetic field may be a DC magnetic field.

The second magnetic field may be an alternating magnetic field or a pulsed magnetic field.

The second magnetic field may be applied in a direction having a predetermined angle with a direction in which the first magnetic field is applied.

The resonance frequency of the magnetic nanoparticles may vary according to the magnitude of the first magnetic field.

The resonance frequency of the magnetic nanoparticles may vary depending on the material or size of the magnetic nanoparticles.

The magnetic nanoparticles may have a diameter in the range of 30 nm to 500 nm.

The magnetic nanoparticles may be selected from the group consisting of Permalloy (Ni 80 Fe 20 ), Maghemite (? -Fe 2 O 3 ), Magnetite (? -Fe 3 O 4 ), Barium Ferrite (Ba x Fe y O z , Composition) and CoFe 2 O 4 .

According to the present invention, there is an effect that an image of a human body can be obtained by applying a magnetic field without using a superconducting magnet.

Further, according to the present invention, since the cost of constructing the medical equipment is reduced and the maintenance cost is low, the burden on the patient can be reduced.

According to the present invention, there is an effect that a signal can be taken quickly with a signal sensitivity higher than that of a magnetic resonance image.

1 is a schematic diagram showing a magnetic nanoparticle having a magnetic vortex structure according to an embodiment of the present invention.
FIG. 2 is a schematic diagram showing magnetization alignment of magnetic nanoparticles with respect to an applied first magnetic field. FIG.
FIG. 3 is a graph showing the change in resonance frequency according to the size of the magnetic nanoparticles relative to the first magnetic field.
FIG. 4 is a schematic diagram showing an exemplary method of applying a DC magnetic field and an AC magnetic field to magnetic nanoparticles to study resonance for a magnetic field applied to the magnetic nanoparticles. FIG.
FIG. 5 is an exemplary graph showing that the carcass motion of a nanoparticle having a given material and size reacts only at a specific resonance frequency.
FIGS. 6 and 7 are schematic diagrams showing the movement of spin-vortex nuclei when external RF pulses are applied / released to the magnetic nanoparticles. FIG.
8 is a graph showing changes in the Z-axis magnetization component and the Y-axis magnetization component of the magnetic nanoparticles upon release of the AC magnetic field application.
9 is a graph showing a free induction decay.
10 is a schematic diagram showing a change in magnetization component in a spin echo method.
11 is a schematic view showing a magnetic vortex resonance imaging apparatus according to an embodiment of the present invention.
12 is a schematic diagram showing a magnet system according to an embodiment of the present invention.

The following detailed description of the invention refers to the accompanying drawings, which illustrate, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, certain features, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in connection with an embodiment. It is also to be understood that the position or arrangement of the individual components within each disclosed embodiment may be varied without departing from the spirit and scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is to be limited only by the appended claims, along with the full scope of equivalents to which such claims are entitled, if properly explained. In the drawings, like reference numerals refer to the same or similar functions throughout the several views.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, in order that those skilled in the art can easily carry out the present invention.

[Magnetic Nanoparticles Having a Self-Vortex Structure]

1 is a schematic diagram showing a magnetic nanoparticle 100 having a magnetic vortex structure 110 according to an embodiment of the present invention.

The magnetic nanoparticles 100 may include a metal, and may include, for example, iron, cobalt, nickel, or an alloy thereof. The magnetic nanoparticles 100 may be ferromagnetic. The magnetic nanoparticles 100 may be made of a material selected from the group consisting of Permalloy (Ni 80 Fe 20 ), Maghemite (? -Fe 2 O 3 ), Magnetite (? -Fe 3 O 4 ), Barium Ferrite (Ba x Fe y O z ; x, y, z can be any composition) and CoFe 2 O 4 . However, the material of the magnetic nanoparticles 100 is not limited thereto.

The magnetic nanoparticles 100 may have a range of sizes having a magnetic vortex structure 110. For example, in the case of a spherical permalloy alloy (Permalloy, Ni 80 Fe 20 ), it may be a spherical body having a diameter ranging from several tens nm to several hundreds of nm, for example, from 30 nm to 500 nm. However, the size and shape of the magnetic nanoparticles are exemplary, and it is also included in the technical idea of the present invention that the magnetic nanoparticle has a shape other than a spherical shape or a diameter larger than 200 nm.

When an external magnetic field of a certain size is externally applied to a magnetic particle of a small size, the magnetic vortex nuclei of the magnetic particle align in the direction of the external magnetic field. When the alternating magnetic field or the pulsed magnetic field of a specific resonance frequency is applied in this aligned state, the magnetic vortex nucleus makes a strong precessional motion around the first magnetic field direction (or the direction of the external magnetic field) Is very similar in morphology to magnetic resonance phenomena of electrons and nuclear spins). When the external magnetic field is applied to the moving magnetic field in the center force field, the magnetic moment of the angular momentum acts on the direction of the external magnetic field as the axis .

The frequency (? MV ) of such a car wash motion is expressed by Equation (1).

[Equation 1]

ω MV = γ eff H DC , [γ eff = γ <m Γ >]

(Where <Γ m> is the mean value of the magnetization in the magnetic vortex core orientation, γ is the gyro magnetic coefficient)

On the other hand, the magnetic nanoparticles 100 having the magnetic vortex structure 110 follow? Eff , and the resonant frequency? MV may be variable according to < m? &Gt; reflecting the size of the nanoparticles.

In the present specification, the magnetic nanoparticles 100 according to the formula (1) will be referred to as "magnetic nanoparticles having a magnetic vortex structure (110) ". For example, when the magnetic nanoparticles 100 have the magnetic vortex structure 110, the magnetic nanoparticles 100 have a resonant frequency that changes according to their diameters.

With further reference to Figure 1, the magnetic nanoparticles 100 may have a magnetic vortex structure 110. The magnetic vortex structure 110 may have a magnetic vortex core component 120, a horizontal magnetization component 130, and a spiral magnetization component 140.

The magnetic vortex core component 120 penetrates the central portion of the magnetic nanoparticles 100, and the direction of the magnetic force can have a + Z direction. The + Z direction can be determined by the direction of the magnetic field previously held by the magnetic nanoparticles 100 or can be determined by the direction of the applied external magnetic field.

The horizontal magnetization component 130 may be positioned to rotate clockwise or counterclockwise with the orbit around the magnetic vortex core 120. The horizontal magnetization component 130 may have a concentric orbit shape depending on the shape, material, and / or crystallographic direction of the magnetic nanoparticles, or may have various types of trajectories such as an ellipse. The horizontal magnetization component 130 may have a predetermined angle with respect to the magnetic vortex core 120 and may be, for example, vertical. However, the horizontal magnetization component 130 may have a magnetization direction component in the direction of the magnetic vortex core 120 or a magnetization direction component in the direction opposite to the magnetic vortex core 120 depending on the physical properties, shape, and / The magnetic vortex core 120 and the horizontal magnetization component 130 may not be perpendicular to each other. The horizontal magnetization component 130 may be present over the entire volume of the magnetic nanoparticles 100.

The spiral magnetization component 140 may be positioned adjacent to the magnetizing vortex core 120 and may be oriented in the same direction as the direction of the magnetizing vortex core 120. [ The spiral magnetization component 140 may be influenced by the horizontal magnetization component 130 and may thus have a spiral-shaped configuration. The magnetization direction of the magnetic nanoparticles 120 may gradually change from the magnetic vortex core 120 to the horizontal magnetization component 130 by the spiral magnetization component 140. That is, the magnetization direction inside the magnetic nanoparticles 120 may gradually change from the Z direction to the Y direction depending on the internal position of the magnetic nanoparticles 100.

2 is a schematic diagram showing the magnetization behavior of magnetic nanoparticles with respect to an applied external magnetic field.

Referring to FIG. 2, the magnetization direction of the magnetic nanoparticles can be changed by an external magnetic field. 2, the + Z direction indicates the average magnetization direction of the magnetic nanoparticles, and the + Y direction indicates the direction of a magnetic field externally applied to the magnetic nanoparticles. . The + Z direction and the + Y direction mean different directions, and they may be perpendicular to each other or may not be perpendicular.

FIG. 2 (a) shows that the magnetic nanoparticles may have a magnetization direction in the + Z direction before an external magnetic field is applied to the magnetic nanoparticles. That is, the magnetic vortex core of the magnetic nanoparticles can be oriented in the + Z direction.

FIG. 2 (b) shows a state immediately after application of a relatively weak external magnetic field to the nanoparticles in the + Y direction. When a magnetic field is applied to the magnetic nanoparticles in the + Y direction which is different from the + Z direction, which is the average magnetization direction of the magnetic nanoparticles, the magnetic vortex cores are oriented in the + Y direction, and magnetic vortices are formed around the magnetic vortex cores do. Subsequently, the magnetization gradually saturates in the + Y direction.

FIG. 3 is a graph showing the change in resonance frequency according to the size of the magnetic nanoparticles relative to the first magnetic field.

Referring to FIG. 3, when the first magnetic field is applied, the resonance frequency decreases as the diameter of the magnetic nanoparticles increases. Also, the resonance frequency increases as the magnitude of the first magnetic field increases. The rate of decrease of the resonance frequency of magnetic nanoparticles of 30 nm or more having a magnetic vortex structure increases sharply as the external magnetic field increases.

Table 1 is a table summarizing the diameter of the magnetic nanoparticles of the permalloy material and the resonance frequency with respect to the size in the external static magnetic field as an embodiment.

10 Oe 50 Oe 100 Oe 200 Oe 300 Oe 20 nm 28 MHz 140 MHz 280 MHz 562 MHz 844 MHz 30 nm 28 MHz 140 MHz 280 MHz 562 MHz 844 MHz 40 nm 24 MHz 124 MHz 250 MHz 516 MHz 782 MHz 60 nm 10 MHz 50 MHz 98 MHz 194 MHz 294 MHz 80 nm 4 MHz 24 MHz 50 MHz 102 MHz 156 MHz 100 nm 2 MHz 16 MHz 32 MHz 64 MHz 98 MHz 120 nm 2 MHz 12 MHz 22 MHz 44 MHz 66 MHz

4 is a schematic diagram showing an exemplary method of applying a direct magnetic field and an alternating magnetic field to the magnetic nanoparticles 100 in order to study resonance with respect to a magnetic field applied to the magnetic nanoparticles 100. FIG.

4, a direct current magnetic field is applied in the + Z direction of the magnetic vortex core component 120 of the magnetic nanoparticles 100, and a direct current magnetic field is applied in a direction different from the + Z direction, Apply an alternating magnetic field. As shown in Table 1, the resonance frequency of the magnetic nanoparticles 100 can be determined according to the diameter of the magnetic nanoparticles 100 and the magnitude of the DC magnetic field. The alternating magnetic field may be smaller than the magnitude of the direct magnetic field, and the behavior of the magnetic nanoparticles 100 is observed by changing the frequency of the alternating magnetic field.

For example, the magnetic nanoparticles 100 have a diameter of 30 nm and a diameter of 80 nm. The DC magnetic field applied in the Z direction is selected to have a magnitude of about 100 Oe. The alternating magnetic field applied in the Y direction is selected to be about 10 Oe. The frequency of the alternating magnetic field is selected to be 281 MHz, which is the resonance frequency of magnetic nanoparticles of 30 nm diameter, and 50 MHz, which is the resonance frequency of magnetic nanoparticles of 80 nm diameter.

FIG. 5 is a graph showing the resonance of magnetic nanoparticles according to the size of magnetic nanoparticles when an alternating magnetic field having a different frequency is applied. 5 (a) and 5 (b) show the case of the magnetic nanoparticles having a diameter of 30 nm, and FIGS. 5 (c) and 5 (d) show the case of the magnetic nanoparticles having the diameter of 80 nm.

Referring to FIG. 5, in the case of a magnetic nanoparticle having a diameter of 30 nm, no change is observed when an alternating magnetic field having a frequency of 50 MHz is applied (see (a)), but the alternating magnetic field having a frequency of 281 MHz When a magnetic field is applied, it shows that strong kinetic motion and magnetization inversion are activated in response to this [(b)].

In the case of magnetic nanoparticles having a diameter of 80 nm, no change occurs when an alternating magnetic field having a frequency of 281 MHz is applied (see (d)), but when an alternating magnetic field having a frequency of 50 MHz, which is its own resonance frequency, is applied In response to this, it is shown that strong motions such as car wash motion and magnetization reversal are activated [c).

That is, when a magnetic field having its own resonance frequency is applied to the magnetic nanoparticles, the magnetic nanoparticles can be activated as the motion such as a car wash motion becomes active due to the magnetic field.

In addition, the magnetic nanoparticles having a magnetic vortex structure have different resonance frequencies depending on the material, size (direct) or first magnetic field (or external magnetic field), so that the magnetic nanoparticles have their own resonance frequency And can be selectively activated depending on the diameter.

[Bio-image acquisition method using magnetic nanoparticles having a self-vortex structure]

Hereinafter, a method of acquiring a bio image using magnetic nanoparticles 100 having a magnetic vortex structure 110 according to an embodiment of the present invention will be described.

According to an embodiment of the present invention, a bioimaging method includes the steps of (a) providing magnetic nanoparticles 100 having a magnetic vortex structure 110, (b) irradiating the magnetic nanoparticles 100 with a resonance frequency (C) applying a second magnetic field having a resonance frequency to the magnetic nanoparticle 100, (d) releasing the application of the second magnetic field to the magnetic nanoparticle 100, (E) a time (T1v) required for recovering the Z-axis magnetization component of the magnetic nanoparticles 100 to a predetermined ratio, or the X-axis or Y-axis magnetization component of the magnetic nanoparticles 100 decreases to a predetermined ratio Measuring an elapsed time T2v, and (f) obtaining a video signal from at least one of T1v or T2v time.

First, in step (a), the magnetic nanoparticles 100 having the magnetic vortex structure 110 may be provided. The provision of the magnetic nanoparticles 100 is carried out in such a manner that the magnetic nanoparticles 100 having the magnetic vortex structure 110 are injected into a specific region of the object 20 from which the image is to be acquired, It can be understood that a part of the magnetic field is moved into the magnet system 250 of the magnetic vortex resonance apparatus 200 (see FIG. 11).

Next, in step (b), the magnetic nanoparticles 100 may have a resonance frequency as the first magnetic field is applied to the magnetic nanoparticles 100. 5 that the magnetic nanoparticles 100 can have a resonant frequency that varies according to their diameters in the case of having the magnetic vortex structure 110. [

The first magnetic field may be a DC magnetic field. The DC magnetic field can be understood as a sperm field formed by the sperm element coil portion 251 (see Fig. 12) of the magnetic vortex resonance apparatus 200 to be described later. The DC magnetic field may be in a range that does not change the magnetic vortex structure 110 of the magnetic nanoparticles 100. For example, when the magnetic nanoparticles are spherical permalloy alloys (Permalloy, Ni 80 Fe 20 ), the direct current magnetic field may range from a few Oe to a few hundred Oe, for example from 10 Oe to 1000 Oe. However, the range of the DC magnetic field is illustrative and not limited thereto. For example, as shown in FIG. 3, the magnitude of the first magnetic field allowed when the size of the magnetic nanoparticles 100 is increased can be increased.

By the first magnetic field direction, the magnetic vortex cores 120 (see FIG. 1) of the magnetic nanoparticles 100 can be aligned in the same direction.

The resonance frequency of the magnetic nanoparticles 100 may vary according to the magnitude of the first magnetic field. For example, as the magnitude of the first magnetic field applied to the magnetic nanoparticles 100 increases, the resonant frequency of the magnetic nanoparticles 100 can be increased.

The resonance frequency of the magnetic nanoparticles 100 may vary depending on the size of the magnetic nanoparticles 100. For example, as the diameter of the magnetic nanoparticles 100 increases, the resonant frequency of the magnetic nanoparticles 100 may decrease. The above-described changes in the resonance frequency of the magnetic nanoparticles 100 can be referred to Table 1 and Table 2 described above.

In addition, the resonant frequency of the magnetic nanoparticles 100 may vary depending on the material, size, and / or shape of the magnetic nanoparticles 100.

Next, in step (c), a second magnetic field equal to the resonance frequency of the magnetic nanoparticles 100 may be applied to the magnetic nanoparticles 100.

The second magnetic field may be an alternating magnetic field or a pulsed magnetic field. The alternating magnetic field can be understood as an RF pulse formed in the RF coil portion 255 (see FIG. 12) of the magnetic vortex resonance apparatus 200 to be described later. The second magnetic field may be applied in a direction having a predetermined angle with respect to the direction in which the first magnetic field is applied, and the direction having the predetermined angle may be perpendicular.

As shown in FIG. 5, the magnetic nanoparticle 100 having the magnetic vortex structure 110 upon application of the second magnetic field has a strong magnetization motion, a magnetization reversal, and the like, and the magnetization axis changes.

Illustratively, FIG. 6 shows the magnetic nanoparticles having a magnetostriction structure in which the external magnetism (or the first magnetic field, the DC magnetic field) B 0 is applied in the Z direction to form a longitudinal axis magnetization, in a direction perpendicular to the B 0 direction The movement of the magnetic vortex nucleus when an external RF pulse (or a second magnetic field, alternating magnetic field) is applied is shown. The long arrows running from left to right in FIG. 6 are time, and the thick arrows in each diagram represent the directions of the magnetic vortex nuclei.

Referring to FIG. 6, the magneto-vortex core is excited by the second magnetic field having the resonance frequency and carries out the car motion, and the magnitude of longitudinal axis magnetization (that is, the magnitude of m Z as the Z direction component of magnetization) gradually decreases, The magnitude of the magnetization (that is, the magnitude of m Y as the Y direction component of magnetization) is increased.

Subsequently, in step (d), the application of the second magnetic field (RF pulse) can be released. As a result, the size of the longitudinal axis magnetization gradually increases and the size of the transverse axis magnetization decreases as the magnetic vortex nucleus in the high energy state in which the transverse magnetization is formed returns to the low energy state in the same direction as the first magnetic field.

Illustratively, FIG. 7 illustrates the motion of the magnetic vortex nuclei when the external RF pulse is removed from the magnetic nanoparticles that are being axially transposed by external RF pulses. The long arrows running from right to left in FIG. 7 are time, and the thick arrows in each diagram represent the directions of the magnetic vortex nuclei.

Referring to FIG. 7, when the external RF pulse is removed, the magneto-vortex nucleus, which has been carrot moving very close to the XY plane before removing the external RF pulse, returns to the B 0 direction, The magnitude of m Z, which is a component in the Z direction of the magnetization) is gradually increased and the magnitude of the transverse magnetization (that is, the magnitude of m Y as the Y direction component of magnetization) is reduced.

FIG. 8 (a) is a graph showing the magnitude (m Z ) of the Z-axis magnetization according to time after removing the external RF pulse. 8 (b) shows a graph showing the magnitude (m Y ) of the Y-axis magnetization with respect to time.

Next, in step (e), the time (T1v) required for recovering the Z-axis magnetization component of the magnetic nanoparticles 100 to a predetermined ratio or the time (T1v) of the magnetic nanoparticles 100 to the X- It is possible to measure the time (T2v) required for the reduction.

As the second magnetic field is released, the magnetic moment direction of the magnetic nanoparticles 100 is accompanied by the magnitude of the longitudinal magnetization (m Z ) and the transverse magnetization (m Y ) In the process, it emits a magnetic vortex resonance signal.

On the other hand, depending on whether or not the magnetic nanoparticles 100 are included in a certain body tissue, the magnetic moment direction of the magnetic nanoparticles 100 in the release of the external RF pulse decreases in the direction of the sperm length and in the transverse direction Time may vary. For example, the magnetic nanoparticles 100 located near the subcutaneous bone marrow and the magnetic nanoparticles 100 located near the muscle tissue are affected by the surrounding body tissues, and the magnetic nanoparticles located near these different body tissues (100) are substantially the same magnetic nanoparticles (100), the recovery behavior after the external RF pulse release is different from each other.

A spin relaxation time (T1-Relaxation Time) or a spin-spin relaxation time (T2-Spin Relaxation Time) is used as a parameter that can represent the difference in the recovery behavior according to an embodiment of the present invention. Relaxation Time.

Specifically, the spin-lattice relaxation time, when the direction of the magnetic moment was rotated by an angle corresponding to the RF pulse applied in the aligned direction by the sperm field, was returned to about 63.2% in the previous direction by the sperm field Lt; / RTI &gt; In other words, the relaxation time T1v (T1v relaxation time) refers to the time required for the Z-axis magnetization component (m Z ) to recover to about 63% of the initial magnetization (m 0 ). This is expressed by Equation 2, where 63% is the value of the natural exponent function (1-e -1 ).

&Quot; (2) &quot;

m Z = m 0 (1- e -t / T1v)

The spin-spin relaxation time is an elapsed time from the time when the RF pulse is blocked to the time when the magnetic nanoparticles 100 reach 36.8% of the maximum energy value, . Back to say, about 63% of the relaxation time T2v (T2v Relaxation Time) is the X-axis or Y-axis magnetization component (m X, m Y) [or, XY plane magnetized component (m XY)] is initially magnetized (m 0) Decrease [or up to 37%]. This is expressed by Equation 3, where 37% is the value of e- 1 .

&Quot; (3) &quot;

m X = m 0 e -t / T 2v , m Y = m 0 e -t / T 2v

Subsequently, in step (f), a video signal can be obtained from at least one of T1v and T2v.

That is, as described above, the spin-lattice relaxation time (T1v) or the spin-spin relaxation time (T2v) of the magnetic nanoparticles (100) can be measured. The time (T1v, T2v) at which the magnetic moment directions of the magnetic nanoparticles (100) located in different body tissues are recovered may be different. The control unit 210 (see FIG. 11) described later can have a pre-input value of T1v and T2v in each body tissue, with respect to the size of each magnetic nanoparticle 100. FIG. Therefore, the control unit 210 can determine the body tissue at the portion where the magnetic nanoparticles 100 are located based on the measured T1v and T2v.

When the magnetic nanoparticle 100 positioned in a specific body tissue is determined to have recovered its magnetic moment direction before the application of the RF pulse, the controller 210 controls the magnetic nanoparticle 100 to apply a predetermined pulse sequence ) Can be applied. That is, when it is determined that the time of T1v or T2v has elapsed, the controller 210 may apply a predetermined magnetic field pulse to the magnetic nanoparticle 100. [ The magnetic field pulses may be various magnetic field pulses such as a spin echo pulse sequence, a gradient echo pulse sequence, or the like.

The RF coil unit 255 (see FIG. 12) to be described later can acquire a video signal (magnetic vortex resonance image signal) of the body tissue in which the magnetic nanoparticles 100 are positioned through a response to the applied magnetic field pulse. The acquired image signal can be digitized to form a self-vortex resonance image and displayed on the display.

9 is a graph showing a free induction decay.

Meanwhile, there is a free induction decay (FID, T2 * Relaxation Time) as a parameter that can represent the difference in the recovery behavior according to another embodiment of the present invention.

Specifically, the free induction attenuation refers to a phenomenon that the transverse magnetization component decreases more rapidly in addition to the relaxation time T2v described above due to the local non-uniformity of the first magnetic field (or DC magnetic field). 9, it is confirmed that the transverse magnetization component (red arrow) in the + Y direction decreases faster than the relaxation time T2v due to local nonuniformity of the first magnetic field (indicated by a plurality of black arrows) .

Free induction decay is about 63% of the relaxation time as consideration to T2 *, X-axis or Y-axis magnetization component (m X, m Y) [or, XY plane magnetization component (m XY)] is initially magnetized (m 0) To [or up to 37%].

The time (T2 *) at which the magnetic moment directions of the magnetic nanoparticles 100 located in different body tissues are recovered may be different. The control unit 210 (see FIG. 11) described below may have a pre-input value of T2 * in each body tissue for the size of each magnetic nanoparticle 100. Therefore, the control unit 210 can determine the body tissue at the portion where the magnetic nanoparticle 100 is located based on the measured T2 *.

When the magnetic nanoparticle 100 positioned in a specific body tissue is determined to have recovered its magnetic moment direction before the application of the RF pulse, the controller 210 controls the magnetic nanoparticle 100 to apply a predetermined pulse sequence ) Can be applied. That is, when it is determined that the time T2 * has elapsed, the controller 210 may apply a predetermined magnetic field pulse to the magnetic nanoparticles 100. The magnetic field pulses may be various magnetic field pulses such as a spin echo pulse sequence, a gradient echo pulse sequence, or the like.

The RF coil unit 255 (see FIG. 12) to be described later can acquire a video signal (magnetic vortex resonance image signal) of the body tissue in which the magnetic nanoparticles 100 are positioned through a response to the applied magnetic field pulse. The acquired image signal can be digitized to form a self-vortex resonance image and displayed on the display.

10 is a schematic diagram showing a change in magnetization component in a spin echo method.

Meanwhile, according to another embodiment of the present invention, there is a spin echo method as a method capable of showing the difference in the recovery behavior.

Specifically, the spindle (red arrow) can be excited by application of an external RF pulse of 90 degrees (or a second magnetic field, alternating magnetic field) (see FIG. 10A). Then, the excited spindle may show a degree of deprecation depending on its environment (see FIG. 10 (b)). The degree of phase dephasing of the spins of the magnetic nanoparticles 100 located in different body tissues may be different.

At this time, when an external RF pulse of 180 degrees is applied, magnetization inversion (transverse magnetization reversal) can be performed on each spindle (see FIG. 10 (c)). A strong magnetic signal can be generated when the deffered spindle is instantaneously maximized by collecting in the same phase by magnetization inversion (see Fig. 10 (d)).

The RF coil portion 255 (see FIG. 12) to be described later can acquire a strong magnetic signal and acquire a video signal (magnetic vortex resonance image signal) of the body tissue where the magnetic nanoparticles 100 are located. The acquired image signal can be digitized to form a self-vortex resonance image and displayed on the display.

[Self-Eddy Resonance Imaging Device]

Hereinafter, a magnetic vortex resonance imaging apparatus 200 according to an embodiment of the present invention will be described. Magnetic Vortex Resonance Imaging is to be understood as an imaging technique using the resonance principle of the magnetic nanoparticle 100 having the magnetic vortex structure 110 described above. In other words, while a magnetic resonance imaging (MRI) apparatus is a device for measuring and imaging the difference in the signal emerging from the resonance of a hydrogen nucleus, the magnetic vortex resonance imaging apparatus is a device for generating a magnetic field having a magnetic vortex structure 110 It should be understood that this is a device for measuring the difference in the signal coming out of the resonance of the nanoparticle 100 and imaging it. In addition, the basic components of the magnetic vortex resonance imaging apparatus can be conceptually the same as the magnetic resonance imaging apparatus.

FIG. 11 is a schematic diagram showing a magnetic vortex resonance imaging apparatus 200 according to an embodiment of the present invention, and FIG. 12 is a schematic diagram showing a magnet system 250 according to an embodiment of the present invention.

Referring to FIG. 11, the magnetic vortex resonance imaging apparatus 200 may include a control unit 210, an operation unit 230, and a magnet system 250. Each constitution is not physically separated as shown in Fig. 11, and can form an integrated constituent.

The control unit 210 can control the static magnetic field coil part 251, the inclined coil part 253, the RF coil part 255, and the like of the magnet system 250. The magnet system 250 can be controlled by interpreting a command related to an operation transmitted from the user via the operation unit 230. Then, the magnetic vortex resonance signal received by the magnet system 250 is analyzed, and a corresponding video signal is generated and transmitted to the display of the operation unit 230. [

The control unit 210 may include a processing unit for analyzing the magnetic vortex resonance signal and generating a video signal, a storage unit for storing a magnetic vortex resonance signal, a video signal, and the like.

The operation unit 230 may include an input device such as a keyboard and a mouse for inputting control of the magnetic vortex resonance imaging device 200 from a user, a display for confirming an image, and the like.

The object 20 may be transferred into the magnet system 250 by a cradle 270.

Referring to FIG. 12, the magnet system 250 may include a sperm excitation coil part 251, an inclined coil part 253, and an RF coil part 255. The magnet system 250 has a cylindrical shape, and may be disposed with the coaxial axis as a central axis, but is not limited thereto. The RF coil part 255 may be arranged in the order of the sperm element coil part 251, the inclined coil part 253 and the RF coil part 255 from the outside, So that it has a hollow shape.

The sperm excitation coil part 251 may form a static magnetic field (or a first magnetic field, a DC magnetic field) in the magnet system 250. The direction of the static magnetic field may be parallel or perpendicular to the longitudinal direction of the object 20, but is assumed to be parallel to the longitudinal direction of the object 20 in this specification.

A permanent magnet, a superconducting magnet, an electromagnet, or the like may be used for the sperm magnetic field coil portion 251. Since the magnetic vortex resonance image of the present invention does not require a high magnetic field of about several T as in a magnetic resonance image, if the sperm excitation coil portion 251 is formed to have a magnetic field of about several to several hundreds of mT Suffice. Therefore, there is an advantage that the equipment cost can be significantly lower than that of the conventional magnetic resonance imaging apparatus.

The inclined coil part 253 can generate a gradient field in the sperm field to form a gradient field. In order to obtain three-dimensional information, an oblique magnetic field with respect to all the X, Y, and Z axes is required, so that the oblique coil part 253 can be provided for the three axes 253a, 253b, and 253c.

When a DC current of the opposite polarity flows in each of the two Z-axis oblique winding portions 253c in the opposite direction, an oblique magnetic field can be formed in the Z-axis direction. The Z-axis inclined coil part 253c can be used for slice selection. A gradient magnetic field by the X-axis and Y-axis inclined coil parts 253a and 253b in the selected plane can be formed, and the frequency and phase can be encoded. Thus, the spatial position of each spindle can be encoded (Spatial Coding).

The RF coil portion 255 can apply an RF pulse (or a second magnetic field, alternating magnetic field) for exciting the magnetic nanoparticles 100 having the magnetic vortex structure 110 in the object 20. The RF coil portion 255 may include a transmitting coil for transmitting an RF pulse and a receiving coil for receiving an electromagnetic wave (magnetic vortex resonance signal) emitted from the excited magnetic nanoparticle 100.

The control unit 210 receives the self-vortex resonance signal transmitted from the RF coil unit 255 and reconstructs the image of the target object 20. The reconstructed image can be displayed on the display of the operation unit 230.

As described above, the present invention generates resonance of the magnetic nanoparticle 100 having the ferromagnetic magnetic vortex structure 110, and since the magnetic field of about several mT to several hundreds of mT is used, it is possible to lower the equipment cost . Since the magnetic nanoparticles 100 exhibit stronger magnetization fractions than hydrogen nuclei and do not utilize nuclear magnetic moment but use magnetic nanoparticles 100 in which magnetic moments of electrons exist in a bundle, The signal sensitivity of about 2000 times that of the resonance image can be obtained and it is possible to take a picture quickly.

As described above, the present invention has been described with reference to particular embodiments, such as specific elements, and specific embodiments and drawings. However, it should be understood that the present invention is not limited to the above- And various modifications and changes may be made thereto by those skilled in the art to which the present invention pertains.

Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

20: object
100: magnetic nanoparticles
110: magnetic vortex structure
120: magnetic vortex core component
130: Horizontal magnetization component
140: Spiral magnetization component
200: magnetic vortex resonance imaging device
210:
230:
250: Magnet system
251: part
253: inclined coil part
255: RF coil part

Claims (15)

(a) providing magnetic nanoparticles having a magnetic vortex structure;
(b) applying a first magnetic field to the magnetic nanoparticles so that the magnetic nanoparticles have a resonant frequency;
(c) applying a second magnetic field having the resonant frequency to the magnetic nanoparticles;
(d) canceling the application of the second magnetic field;
(e) measuring a time T1v required for recovering the Z-axis magnetization component of the magnetic nanoparticles to a predetermined ratio, or a time T2v required for decreasing the X-axis or Y-axis magnetization component of the magnetic nanoparticles to a predetermined ratio; And
(f) obtaining a video signal from at least one of the T1v and the T2v;
Wherein the bio image acquiring step comprises: The method according to claim 1,
Wherein T1v is the longitudinal axis relaxation time of the magnetic nanoparticles in the body tissue. The method according to claim 1,
And T2v is the transverse axis relaxation time of the magnetic nanoparticles in the body tissue. The method of claim 3,
And T2v is a free induction decay added to the transverse axis relaxation time. The method according to claim 1,
Wherein the predetermined ratio is 63%. The method according to claim 1,
Wherein T1v and T2v have predetermined values according to the material, size, intensity of the first magnetic field and surrounding body tissue of the magnetic nanoparticles. The method according to claim 6,
Wherein T1 v or T2 v of the plurality of magnetic nanoparticles is contrasted with a preset value to acquire an image signal of a body tissue in which the magnetic nanoparticles are located. The method according to claim 1,
The step (f)
(f1) applying a predetermined magnetic field pulse to the magnetic nanoparticles at the time T1v or T2v; And
(f2) acquiring a video signal of a body tissue in which the magnetic nanoparticles are positioned through a response to the magnetic field pulse
Wherein the bio image acquiring step comprises: The method according to claim 1,
Wherein the first magnetic field is a DC magnetic field. The method according to claim 1,
Wherein the second magnetic field is an alternating magnetic field or a pulsed magnetic field. The method according to claim 1,
Wherein the second magnetic field is applied in a direction having a predetermined angle with a direction in which the first magnetic field is applied. The method according to claim 1,
Wherein the resonance frequency of the magnetic nanoparticles changes according to the magnitude of the first magnetic field. The method according to claim 1,
Wherein the resonance frequency of the magnetic nanoparticles varies depending on the material or size of the magnetic nanoparticles. The method according to claim 1,
Wherein the magnetic nanoparticles have a diameter ranging from 30 nm to 500 nm. The method according to claim 1,
The magnetic nanoparticles may be selected from the group consisting of Permalloy (Ni 80 Fe 20 ), Maghemite (? -Fe 2 O 3 ), Magnetite (? -Fe 3 O 4 ), Barium Ferrite (Ba x Fe y O z , Composition) and CoFe 2 O 4 .
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Publication number Priority date Publication date Assignee Title
KR20200029221A (en) * 2018-09-10 2020-03-18 서울대학교산학협력단 Heating method of magnetic nano particles

Citations (1)

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Publication number Priority date Publication date Assignee Title
JP2012525193A (en) 2009-04-30 2012-10-22 コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ Apparatus and method for magnetic resonance imaging by influencing and / or detecting magnetic particles

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012525193A (en) 2009-04-30 2012-10-22 コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ Apparatus and method for magnetic resonance imaging by influencing and / or detecting magnetic particles

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20200029221A (en) * 2018-09-10 2020-03-18 서울대학교산학협력단 Heating method of magnetic nano particles
KR102172017B1 (en) 2018-09-10 2020-10-30 서울대학교산학협력단 Heating method of magnetic nano particles

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