Combined ultrahigh-field double-tuning-head coil

Abstract

The invention belongs to the technical field of magnetic resonance ultrahigh fields, and discloses a combined ultrahigh-field double-tuning-head coil which is used for head nuclear magnetic resonance imaging detection and comprises a birdcage coil located outside and a multi-channel radio frequency array coil located inside, and the birdcage coil and the multi-channel radio frequency array coil are coaxially arranged and mutually independent. The birdcage coil is responsible for signal emission and reception of 1H cores and heteronuclear signal emission, and the multi-channel radio frequency array coil is responsible for heteronuclear signal reception; the birdcage coil adopts a band-pass mode and comprises two end rings and a plurality of cage legs, and a double-tuned circuit is arranged between the adjacent cage legs on each end ring; and on the multi-channel radio frequency array coil, two trap circuits are arranged in parallel between the active protection loop and the passive protection loop of each channel. Through organic combination of the two coils, the hydrogen nucleus and heteronuclear double-tuning imaging effect in the ultrahigh field is achieved, imaging is clear, and the problems that the birdcage coil heteronuclear signal is not strong and imaging is not good in the ultrahigh field are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetic resonance ultra-high field, and in particular relates to a combined ultra-high field double-tuning head coil. Background Art

[0002] The MRI birdcage coil is a radio frequency coil specially designed for nuclear magnetic resonance imaging. It is cylindrical in shape and consists of multiple metal conductor strips arranged around a central area to form a shape similar to a birdcage. This design can provide a relatively uniform radio frequency field throughout the imaging area and obtain high-quality images. During scanning, the birdcage coil excites hydrogen atoms in the body by applying radio frequency pulses. When the hydrogen atoms return to the ground state, they emit signals that are received by the coil and used for image reconstruction. The birdcage coil can effectively capture signals from a large volume area and is suitable for large-scale imaging. It can be used for many types of scans, especially performing well in body and brain imaging.

[0003] At present, the technology for realizing hydrogen nuclear magnetic resonance imaging by using magnetic resonance birdcage coil imaging coils has been relatively mature, but only hydrogen nucleus imaging can no longer meet people's needs for disease diagnosis. People have found that dual-nuclear magnetic resonance imaging can present more morphological and metabolic information in biological systems, so people have turned their attention to the research of dual-nuclear and multi-nuclear magnetic resonance imaging technology. Therefore, in addition to the research on the imaging of hydrogen nuclei, the industry has also imaged heteronuclei such as 13C, 23Na, 31P, and 19F. However, the stock of these heteronuclei in the body is small, and the signal on the magnetic resonance under conventional field strength is relatively weak. It can only be captured under high fields greater than 3 Tesla or even ultra-high fields up to 7 Tesla. By capturing these heteronuclear signals, it is convenient to detect functional problems in samples, and it is also convenient to realize multi-element detection and timely discover functional problems. However, under high or ultra-high fields, higher frequencies mean that the radio frequency wavelength is relatively short, resulting in more prominent magnetic field inhomogeneity generated by the radio frequency coil, which seriously reduces the contrast of the image, affects the image quality, and makes the imaging unclear.

[0004] A multi-channel MRI coil is a device that can be used to enhance MRI technology. It consists of multiple receiving coils that can simultaneously receive signals from different areas of the body. Multiple coils can simultaneously collect signals, thereby increasing the signal-to-noise ratio of the image and improving imaging quality. Multi-channel systems can support faster imaging sequences, reduce scan time, and improve patient comfort. With multiple coils, higher spatial resolution can be achieved, especially when observing small structures. Different coils can be optimized for different body positions or scan areas to provide more accurate imaging.

[0005] Based on the existing problems, the inventors thought that since the birdcage coil can only transmit and receive signals of 1H nuclei and transmit heteronuclear signals under ultra-high fields, but cannot receive high-quality heteronuclear signals, a multi-channel RF array coil should be added to receive heteronuclear signals. However, the problem of tuning the resonant frequencies of the two nuclei needs to be solved to solve the problem of mutual interference of signals.

[0006] Therefore, people hope to find a new structure that can realize dual-tuned magnetic resonance imaging coils under ultra-high fields. Summary of the invention

[0007] The purpose of the present invention is to provide a combined ultra-high field dual-tuned head coil, in which a multi-channel magnetic resonance imaging coil is added to the birdcage coil. Through the organic combination of the two coils, a hydrogen nucleus + heteronucleus dual-tuned imaging effect is achieved to solve the problem of weak heteronuclear signals and poor imaging of the birdcage coil under ultra-high fields.

[0008] In order to achieve the above technical purpose, the technical solution adopted by the present invention is: A combined ultra-high field dual-tuned head coil, used for head magnetic resonance imaging detection, comprises an external birdcage coil and an internal multi-channel radio frequency array coil, the birdcage coil and the multi-channel radio frequency array coil are coaxially arranged and independent of each other, the birdcage coil is responsible for signal transmission and reception of 1H nuclei and signal transmission of heteronuclei, and the multi-channel radio frequency array coil is responsible for signal reception of heteronuclei; The birdcage coil adopts a bandpass mode, including two end rings and a plurality of cage legs, the two ends of each cage leg are respectively connected to the two end rings, and a double-tuned circuit is provided between adjacent cage legs on each end ring, and the double-tuned circuit is formed by connecting a second capacitor and a second inductor in parallel with the first capacitor in series; On the multi-channel radio frequency array coil, two trap circuits are arranged in parallel between the active protection circuit and the passive protection circuit of each channel, and the trap circuit is composed of a third capacitor and a third inductor connected in parallel.

[0009] As a preferred technical solution, the birdcage coil and the multi-channel radio frequency array coil are independent of each other and are connected by a fixing frame.

[0010] As a preferred technical solution, two signal lines are connected to the birdcage coil, and one signal line is connected to the multi-channel radio frequency array coil, and each signal line is used to connect to a magnetic resonance host.

[0011] As a preferred technical solution, the birdcage coil is a 16-legged birdcage coil.

[0012] As a preferred technical solution, the length of the cage legs of the birdcage coil is 26 cm.

[0013] As a preferred technical solution, the multi-channel radio frequency array coil is a 32-channel radio frequency array coil.

[0014] As a preferred technical solution, the selection formula of the equivalent capacitance in the double-tuned circuit is: in, : angular frequency, is an imaginary unit, L 2 is the inductance of the second inductor, C 1 is the capacitance of the first capacitor, C 2 is the capacitance of the second capacitor, C x is the equivalent capacitance of 1H heteronuclear.

[0015] As a preferred technical solution, the field strength of the ultra-high field is greater than 7T.

[0016] The beneficial effects of the present invention are: A combined ultra-high field dual-tuning head coil of the present invention has an ingenious structure. Through the organic combination of the birdcage coil and the multi-channel radio frequency array coil, the signal acquisition efficiency and imaging quality are greatly improved, thereby achieving a hydrogen nucleus + heteronuclear dual-tuning imaging effect under ultra-high field, and the imaging is clear, solving the problem of weak heteronuclear signals and poor imaging of the birdcage coil under ultra-high field. It is of great significance for achieving early discovery of functional problems or minor problems in samples, has great social value, is highly practical, and is worthy of promotion.

[0017] A combined ultra-high field dual tuning head coil of the present invention is designed with independent tuning elements and coil structures to tune the resonance frequencies of heteronuclei and 1H nuclei respectively, that is, an independent tuning capacitor (first capacitor C1) is used to adjust the resonance frequency of the heteronuclei, and another tuning capacitor (second capacitor C2) is used to adjust the resonance frequency of the 1H nuclei, so as to achieve the purpose of tuning the resonance frequencies of the two nuclei respectively; dual tuning is achieved by adjusting the coupling structure inside the birdcage coil, that is, by adjusting the parameters of the coupling capacitor, the coupling degree between the heteronuclei and the 1H nuclei is changed, thereby achieving the adjustment of the resonance frequencies of the two nuclei; the interaction between the birdcage coil and the multi-channel RF sub-array coil affects the distribution and intensity of the RF field, and a trap circuit is added to each channel of the multi-channel RF array coil to remove the influence of the 1H signal in the birdcage coil, that is, the current distribution and phase relationship between the coils are accurately adjusted to ensure good matching and coupling between the coils, thereby obtaining a uniform RF field. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a schematic diagram of a three-dimensional disassembled structure of an embodiment of the present invention; Figure 2 Schematic diagram of the coordination principle between the birdcage coil and the multi-channel radio frequency array coil in an embodiment of the present invention; Figure 3 is a schematic diagram of the three-dimensional structure of a birdcage coil in an embodiment of the present invention; Figure 4 Schematic diagram of the structure of a double-tuned circuit arranged on a birdcage coil in an embodiment of the present invention; Figure 5 It is a structural schematic diagram of adding a trap circuit in each channel of a multi-channel radio frequency array coil in an embodiment of the present invention; Figure 6 Schematic diagram of the structure of the trap circuit in the embodiment of the present invention.

[0020] Reference numerals: 1 - birdcage coil, 2 - multi-channel radio frequency array coil. DETAILED DESCRIPTION

[0021] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians of the art without making creative work are within the scope of protection of the present application.

[0022] A combined ultra-high field dual-tuning head coil, such as Figure 1-Figure 6 As shown, it is used for head magnetic resonance imaging detection, including a birdcage coil 1 located outside and a multi-channel radio frequency array coil 2 located inside, the birdcage coil 1 and the multi-channel radio frequency array coil 2 are coaxially arranged and independent of each other, the birdcage coil 1 is responsible for the signal transmission and reception of 1H nuclei and the signal transmission of heteronuclei, and the multi-channel radio frequency array coil 2 is responsible for the signal reception of heteronuclei; the field strength of the ultra-high field is greater than 7T.

[0023] The birdcage coil 1 adopts a bandpass mode, including two end rings and a plurality of cage legs, the two ends of the cage legs are respectively connected to the two end rings, and a double tuning circuit is provided between adjacent cage legs on each end ring, and the double tuning circuit is formed by connecting a second capacitor C2 and a second inductor L2 in parallel and in series with a first capacitor C1, so that it can support two different resonant frequencies and form two different resonant modes; the tuning circuit is composed of a capacitor and an inductor, and tuning can be achieved by adjusting the parameters of the capacitor and the inductor; the selection formula of the equivalent capacitor in the double tuning circuit is: in, : angular frequency, is an imaginary unit, L 2 is the inductance of the second inductor, C 1 is the capacitance of the first capacitor, C 2 is the capacitance of the second capacitor, C x is the equivalent capacitance of 1H heteronuclear.

[0024] On the multi-channel RF array coil, two trap circuits (i.e., Traps) are arranged in parallel between the active protection circuit and the passive protection circuit of each channel. The trap circuit is composed of a third capacitor C3 and a third inductor L3 connected in parallel, so as to shield the signal of the birdcage coil 1H core so that it does not affect the multi-channel RF array coil.

[0025] The birdcage coil 1 and the multi-channel radio frequency array coil 2 are independent of each other and are connected by a fixing frame.

[0026] The birdcage coil 1 is connected to two signal lines, and the multi-channel radio frequency array coil 2 is connected to one signal line, and each signal line is used to connect to a nuclear magnetic resonance host.

[0027] The multi-channel radio frequency array coil is a 32-channel radio frequency array coil.

[0028] The bird cage coil is a 16-leg bird cage coil, and the length of the cage legs is 26 cm, which is determined by simulation rules.

[0029] The combined ultra-high field dual-tuning head coil of the present invention has an ingenious structure. Through the organic combination of the two coils, the signal collection efficiency and imaging quality are greatly improved, thereby achieving the hydrogen nucleus + heteronucleus dual-tuning imaging effect under ultra-high field, and the imaging is clear, which solves the problem of weak heteronuclear signal and poor imaging of the birdcage coil under ultra-high field. It is of great significance for realizing the early discovery of functional problems or minor problems in samples, has great social value, strong practicality, and is worthy of promotion.

[0030] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A combined ultra-high field dual-tuned head coil for head magnetic resonance imaging detection, characterized in that: It includes a birdcage coil located outside and a multi-channel radio frequency array coil located inside, the birdcage coil and the multi-channel radio frequency array coil are coaxially arranged and independent of each other, the birdcage coil is responsible for the signal transmission and reception of 1H nuclei and the signal transmission of heteronuclei, and the multi-channel radio frequency array coil is responsible for the signal reception of heteronuclei; The birdcage coil adopts a bandpass mode, including two end rings and a plurality of cage legs, the two ends of each cage leg are respectively connected to the two end rings, and a double-tuned circuit is provided between adjacent cage legs on each end ring, and the double-tuned circuit is formed by connecting a second capacitor and a second inductor in parallel with the first capacitor in series; On the multi-channel radio frequency array coil, two trap circuits are arranged in parallel between the active protection circuit and the passive protection circuit of each channel, and the trap circuit is composed of a third capacitor and a third inductor connected in parallel.

2. The combined ultra-high field dual tuning head coil according to claim 1, characterized in that: The birdcage coil and the multi-channel radio frequency array coil are independent of each other and are connected by a fixing frame.

3. The combined ultra-high field dual tuning head coil according to claim 1, characterized in that: The birdcage coil is connected to two signal lines, and the multi-channel radio frequency array coil is connected to one signal line, and each signal line is used to connect to a magnetic resonance host.

4. The combined ultra-high field dual tuning head coil according to claim 1, characterized in that: The birdcage coil is a 16-leg birdcage coil.

5. The combined ultra-high field dual tuning head coil according to claim 4, characterized in that: The length of the cage legs of the bird cage coil is 26 cm.

6. The combined ultra-high field dual tuning head coil according to claim 1, characterized in that: The multi-channel radio frequency array coil is a 32-channel radio frequency array coil.

7. The combined ultra-high field dual tuning head coil according to claim 1, characterized in that: The formula for selecting the equivalent capacitance in the double-tuned circuit is: in, : angular frequency, is an imaginary unit, L 2 is the inductance of the second inductor, C 1 is the capacitance of the first capacitor, C 2 is the capacitance of the second capacitor, C x is the equivalent capacitance of 1H heteronuclear.

8. The combined ultra-high field dual tuning head coil according to any one of claims 1 to 7, characterized in that: The field strength of the ultra-high field is greater than 7T.

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