This application claims the benefit of Korean Patent Application No. 10-2008-0117476, filed on Nov. 25, 2008, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a magnetic resonance imaging (MRI), and more particularly, to a magnetic resonator capable of improving MRI resolution and an application device including the same.
2. Description of the Related Art
A magnetic resonance imaging (MRI) technique is a high-end non-destructive non-radioactive technique that has high efficacy and is not harmful to human bodies. MRI is commonly used to diagnose brain diseases, spinal diseases, bone diseases, joint diseases, cardiovascular diseases, chest diseases, congenital heart diseases, and myocardial infarction. An MRI technique uses the following principle: when a static magnetic field is applied to a human body, hydrogen nuclei included in cell forming molecules attain resonance frequency that is proportional to the intensity of the static magnetic field and easily absorb or emit an electromagnetic wave having the resonance frequency.
MRI devices may visualize the internal structure of a human body based on the principle described above. MRI devices, when a strong static magnetic field having flux density of about 1 Tesla is applied to a measurement site, irradiate a portion of human body with electromagnetic waves of the resonance frequency in a pulse form so as to excite hydrogen nuclei into a high energy state. When the excited hydrogen nuclei return to a low energy state, the hydrogen nuclei release most of their energy in the form of a magnetic field. The emitted magnetic field is a magnetic resonance (MR) signal.
If, when hydrogen nuclei emit a magnetic field, other magnetic fields having different intensities according to position, for example, a gradient magnetic field in which intensity is increased in proportion to a distance in one direction from a reference point, are additionally added to the strong static field, frequencies of magnetic fields emitted by hydrogen nuclei at various positions have derivations proportional to position with respect to a center frequency determined by the static magnetic field. Accordingly, when the MR signals are received by a detector or a receiving antenna and then processed, an image showing a density distribution of hydrogen nuclei can be obtained.
The higher the resolution an MRI technique is, the more accurate a diagnosis can be performed. Thus, during measuring, a signal detector is located as close as possible to human bodies so as to prevent a reduction in MR signals. However, there is always a predetermined interval between human bodies and signal detectors, and in this case, sensitivity is significantly decreased. For example, in cases where surgery is performed while doing real-time MRI, a MR detector used does not contact a human body and is located in a space surrounded by a barrier for preventing permeation of bacteria and thus MR signals detected are reduced in intensity and MRI resolution may be degraded.
Meanwhile, MRI resolutions can be increased by using a magnetic resonator for amplifying MR signals. However, the magnetic resonator also has a limitation on reducing an interval with respect to human bodies. Thus, there is still a need to increase a MRI resolution.
The present invention provides a magnetic resonator capable of improving
MRI resolution. The magnetic resonator is attached to a human body and conforms to the shape of the human body. In addition, the location of the magnetic resonator relative to human body needs not be considered by using a plurality of small magnetic resonators simultaneously.
The present invention also provides an application device including the magnetic resonator.
According to an aspect of the present invention, there is provided a wearable magnetic resonator including: a dielectric thin film that is flexible; and a conductor thin film that is disposed to have a split ring resonator (SRR) structure on the dielectric thin film and that is flexible, wherein the wearable magnetic resonator includes an inductance component and a capacitance component, and the wearable magnetic resonator amplifies a magnetic field by resonating at a predetermined frequency, thereby improving magnetic resonance imaging (MRI) resolution. The conductor thin film may be ring-shaped, and may have a gap that is a split portion of the conductor thin film and thus has the capacitance component. For example, the conductor thin film may be circular ring-shaped or square ring-shaped. The dielectric thin film may be interposed between a pair of the conductors, and the gaps of the conductor thin films are disposed on opposite sides.
The conductor thin film may include first and second conductors each being a ring-shaped, wherein the first and second conductors have the same size or different sizes, wherein when the first and second conductors have the same size, the first conductor is disposed on a top surface of the dielectric thin film and the second conductor is disposed on a bottom surface of the dielectric thin film, and when the first and second conductors have different sizes, the second conductor is disposed inside the ring structure of the first conductor, wherein gaps of the first and second conductors are disposed on opposite sides. For example, the conductor thin film may include first and second conductors each being a square ring-shaped, wherein the first and second conductors have the same size and the first conductor is disposed on a top surface of the dielectric thin film and the second conductor is disposed on a bottom surface of the dielectric thin film, and each of the first and second conductors has a gap that is a split portion formed in one side of the corresponding square ring-shaped conductor and thus has the capacitance component. The gap of the first conductor and the gap of the second conductor are disposed on opposite sides. The conductor thin film may also be formed by printing a conductive ink on one surface or opposite surfaces of the dielectric thin film.
According to an aspect of the present invention, there is provided a wearable magnetic resonator assembly including a plurality of the wearable magnetic resonators.
According to an aspect of the present invention, there is provided a magnetic resonator application device including the wearable magnetic resonator or the wearable magnetic resonator assembly. For example, the magnetic resonator application device may be a cloth or portable device that is wearable.
The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:
Exemplary embodiments of the present invention will now be described more fully with reference to the accompanying drawings. In regard to the description to be presented, it will be understood that when a layer is referred to as being “on” or “under” another layer, it can be directly on or under the other layer, or intervening layers may also be present. In the drawings, the sizes or shapes of forming elements are exaggerated for convenience for description and clarity, and other forming elements that are not used to describe embodiments of the present invention are not shown. In the drawings, like reference numerals denote like elements. Meanwhile, terms are used in descriptive sense only and not for purposes of limitations on meanings or the scope of the present invention defined in the claims.
A magnetic resonator according to the present invention is a type of split ring resonator (SRR) capable of amplifying a magnetic resonance (MR) signal by being attached to a human body. SRRs resonate when an external magnetic field corresponding to a self resonance frequency is applied to the SRRs and amplify the magnetic field. Hereinafter, an SRR and a magnetic resonator will be used as the same concept.
Referring to
When the intensity of an external magnetic field M that penetrating perpendicularly through the conductor (101) is changed, an induced current B may flow along a circumferential direction of the conductor (101) according to an electromagnetic rule and the induced current also induces magnetic field that passes through and is perpendicular to the conductor (101). Since the conductor (101) has an inductance component, L, and the gap A has a capacitance component, C, the entire structure of the conductor (101) may be modeled as an L-C resonance circuit. Thus, by appropriately controlling L and C, resonance may be obtained at a desired frequency. A resonance frequency fr of the L-C resonance circuit may be obtained using Equation 1.
f
r=1/{2π(LC)1/2} Equation 1
Meanwhile, as described above, if the frequency of the external magnetic field M is similar to the resonance frequency fr, a high induced current flows and thus a high induced magnetic field is generated, thereby amplifying a magnetic field. Referring to
Referring to
In
Referring to
Unlike the SRR structure including a single conductor ring as illustrated in
Hereinbefore, various SRRs are exemplarily illustrated, but a SRR according to an embodiment of the present invention is not limited thereto. For example, although the conductors illustrated in
Various SRRs according to the previous embodiments, that is, magnetic resonators may be implemented by a flexible thin film structure by using a flexible thin conductor film and a flexible dielectric thin film. Such a magnetic resonator having flexibility may be attached to and placed as close as possible to or contacting a human body regardless of the surface shape or location of the human body, and thus, a MR signal can be effectively amplified and thus, a MRI resolution may be significantly improved.
For reference, the SRRs as described above are researched as being a part of a meta-material having a negative refractive index with respect to an electromagnetic wave rather than being applied in particular technical application fields [J. B. Pendry, A. J. Holden, D. J. Robbins, and W. J. Stewart, “Magnetism from conductors and enhanced nonlinear phenomena,” IEEE Trans. on Microwave theory and tech., Vol. 47, No. 11, Nov., 1999.]. Conventionally, SRRs are formed in a usual printed circuit board (PCB) which is a hard device. However, according to the present invention, a SRR is manufactured using a flexible dielectric film with thin conductor films on both sides of it. Thus, the SRR is very flexible and can be directly attached to a human skin, or SRR-including clothes or portable devices can be manufactured and humans can wear them. By doing so, when MR signals are captured, the magnetic field is amplified and high resolution can be obtained.
Referring to
As described with reference to
Meanwhile, although not illustrated, each of the SRRs illustrated in
The wearable SRR (200) has the structure illustrated in
Referring to
As illustrated in
For a wearable magnetic resonator capable of improving MRI resolutions according to the present invention and an application device including the same, a highly flexible SRR may be used, and thus, the wearable magnetic resonator can be attached to and located conforming to the shape of a human body. In addition, a relative location between the human body and the wearable magnetic resonator need not to be considered by using a plurality of the small wearable magnetic resonators. Therefore, since MRIs can be captured while the wearable magnetic resonator is attached to the human body, MR signals can be effectively amplified and MRI resolutions can be significantly improved.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.
Number | Date | Country | Kind |
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10-2008-0117476 | Nov 2008 | KR | national |