CN215494071U

CN215494071U - Magnetic resonance radio frequency coil structure for replacing connector

Info

Publication number: CN215494071U
Application number: CN202121457630.3U
Authority: CN
Inventors: 张松涛; 沈江; 林海洋; 何钧
Original assignee: Shanghai Chenguang Medical Technologies Co ltd
Current assignee: Shanghai Chenguang Medical Technologies Co ltd
Priority date: 2021-06-29
Filing date: 2021-06-29
Publication date: 2022-01-11
Anticipated expiration: 2031-06-29

Abstract

The utility model relates to the technical field of magnetic resonance, in particular to a magnetic resonance radio frequency coil structure for replacing a connector. A magnetic resonance radio frequency coil structure for replacing a connector comprises an upper coil part and a lower coil part, and is characterized in that: the upper part sub-coil comprises a first resonant circuit and a first inductor, and the first resonant circuit is connected with the first inductor in series; the lower part coil comprises a second resonance circuit, a second inductor and a preamplifier, the second resonance circuit is connected with the preamplifier, and the second inductor is connected in series between the second resonance circuit and the preamplifier. Compared with the prior art, the magnetic resonance radio frequency coil structure with the connector replaced is provided, and signals can be fed into the preamplifier in the lower half part from the resonance loop of the channel in the upper half part without using a coaxial connector.

Description

Magnetic resonance radio frequency coil structure for replacing connector

Technical Field

The utility model relates to the technical field of magnetic resonance, in particular to a magnetic resonance radio frequency coil structure for replacing a connector.

Background

Magnetic resonance imaging is an advanced technique for non-destructive imaging of the human body and is widely applied to diagnosis of diseases of various parts of the human body. The performance of the magnetic resonance radio frequency coil, which is an important component of the magnetic resonance imaging system, directly determines the quality of the magnetic resonance imaging.

The multi-channel phased array radio frequency coil is the mainstream of the current magnetic resonance radio frequency coil because of high signal-to-noise ratio and high parallel scanning capability. With the technical progress, the number of channels of the magnetic resonance radio frequency coil is increased, at present, 16 channels, 32 channels are standard configuration, and even 64 channels are widely used.

Many coils, such as head coils, head and neck coils, knee joint coils, etc., are hard coils, and their structures are generally composed of an upper part and a lower part which can be opened, wherein a part of coil channels are located at the lower half part of the coil, a part of coil channels are located at the upper half part of the coil, and another part of coil channels span the upper half part and the lower half part.

In general, the sizes of the upper and lower portions of the coil do not differ greatly, so the channel numbers of the upper and lower portions do not differ greatly. The larger the number of channels, the larger the number of connectors required, and for a 32-channel head coil, usually 10 channels are located entirely in the upper half, so at least 10 coaxial connectors are required. The cost of the coil is drastically increased since the nonmagnetic connector, especially the nonmagnetic coaxial connector, is very expensive. Even worse, the engagement and disengagement of the upper and lower parts is very laborious with 10 coaxial connectors plus a large number of dc connectors. Since the coaxial connectors are required to have high dimensional accuracy, the reliability of the coil is drastically reduced with the number of connectors.

Disclosure of Invention

The present invention overcomes the deficiencies of the prior art by providing an alternative connector for a magnetic resonance radio frequency coil structure that allows signals to be fed from the resonant tank of the channel in the upper half to the preamplifier in the lower half without the use of a coaxial connector.

In order to achieve the purpose, the magnetic resonance radio frequency coil structure for replacing the connector is designed, and comprises an upper coil part and a lower coil part, and is characterized in that: the upper part sub-coil comprises a first resonant circuit and a first inductor, and the first resonant circuit is connected with the first inductor in series; the lower part coil comprises a second resonance circuit, a second inductor and a preamplifier, the second resonance circuit is connected with the preamplifier, and the second inductor is connected in series between the second resonance circuit and the preamplifier.

And a first capacitor is connected in series between the first resonant loop and the first inductor.

And two ends of the second inductor are connected with the input end of the preamplifier.

And a second capacitor is connected in series between the second inductor and the preamplifier.

The first inductor and the second inductor are close to each other to form effective mutual inductance coupling.

The first inductor and the second inductor are planar spiral inductors.

The outer sides of the upper part branching coil and the lower part branching coil are respectively connected with a plane, and a first inductor and a second inductor are respectively arranged in the upper plane and the lower plane.

The distance between the first inductor and the second inductor is 4-8 mm.

Compared with the prior art, the utility model provides the magnetic resonance radio frequency coil structure which replaces a connector, and can feed signals from a resonance loop of a channel positioned at the upper half part to a preamplifier positioned at the lower half part without using a coaxial connector.

Drawings

FIG. 1 is a schematic diagram of a conventional coil resonant tank and preamplifier connection.

FIG. 2 is a schematic diagram of the connection of the present invention.

Fig. 3 is a schematic layout diagram of the first inductor and the second inductor.

FIG. 4 is a top view of an embodiment of the present invention.

FIG. 5 is a side view of an embodiment of the present invention.

Referring to fig. 2 to 5, 1 is a first resonant circuit, 2 is a second resonant circuit, 3 is a preamplifier, 4 is 11 channels, 5 is an upper half, 6 is a lower half, L1 is a first inductor, L5 is a second inductor, C6 is a first capacitor, and C11 is a second capacitor.

Detailed Description

The utility model is further illustrated below with reference to the accompanying drawings.

As shown in fig. 2 and 3, the upper sub-coil includes a first resonant circuit and a first inductor, and the first resonant circuit 1 is connected with the first inductor L1 in series; the lower part coil comprises a second resonance loop, a second inductor and a preamplifier, wherein the second resonance loop 2 is connected with the preamplifier 3, and the second inductor L5 is connected between the second resonance loop 2 and the preamplifier 3 in series.

The capacitor-C6 is connected in series between the resonant tank-1 and the inductor-L1.

The two ends of the inductor two L5 are connected with the input end of the preamplifier 3.

And a capacitor two C11 is connected in series between the inductor two L5 and the preamplifier 3.

The first inductor L1 and the second inductor L5 are close to each other, and effective mutual inductance coupling is formed.

The first inductor L1 and the second inductor L5 are planar spiral inductors.

The outer sides of the upper branching coil and the lower branching coil are respectively provided with a plane in a connected mode, and the upper plane and the lower plane are respectively provided with a first inductor L1 and a second inductor L5.

The distance between the first inductor L1 and the second inductor L5 is 4-8 mm.

The utility model discloses a magnetic resonance radio frequency coil structure for reducing the usage amount of a connector, which is different from the signal connection mode that a signal feed-in point capacitor is connected in series in a traditional coil resonance loop and two ends of the feed-in point capacitor are directly connected to the input end of a preamplifier, in the utility model, the originally connected circuit is divided into two independent resonance loops which are not directly connected, a first resonance loop 1 is positioned at the upper half part of a coil and is used for detecting a signal for a coil channel, and an inductor L1 is connected in series in the resonance loop; the second resonant circuit 2 and the preamplifier 3 are both located at the lower half part of the coil, and the second resonant circuit 2 is composed of an inductor two L5, a possible tuning capacitor and impedance matching components such as a capacitor and an inductor inside the preamplifier 3. The first inductor L1 and the second inductor L5 are respectively positioned on the upper half part and the lower half part of the coil and are close to each other in space, so that strong mutual inductance is generated, and magnetic resonance radio frequency signals detected by the first resonant loop 1 are transmitted to the preamplifier 3 positioned on the lower half part and are transmitted to a magnetic resonance system through a system cable positioned on the lower half part. The mutual inductance of the mutual coupling can replace the connector to play a role in signal transmission, so that the use amount of the connector is reduced.

The utility model has the advantages that the number of connectors for connecting different parts of the coil, especially the number of coaxial connectors, can be greatly reduced, thereby reducing the cost of the coil, improving the use convenience and improving the reliability of the product.

The first embodiment is as follows: as shown in fig. 4 and 5, the structure and channel distribution of a thirty-channel neck-chest combined coil are schematically illustrated, wherein the coil has eight channels in a circle at the top of the head, eight channels in a circle at the face, eight channels in a circle at the neck, three channels at the upper chest and three channels at the lower chest. It should be noted that the schematic drawing shows only the distribution positions of the channels, but does not show the overlapping relationship between the channels, nor the connector. The coil is made up of two parts, an upper half 5 and a lower half 6, where eleven channels 4 are located entirely in the upper half 5.

A common connection method between a radio frequency coil resonant circuit and a preamplifier is shown in fig. 1, a capacitor C4 is selected and arranged in the resonant circuit as a signal feed-in point capacitor, two ends of the feed-in point capacitor C4 are respectively connected to input ends of the amplifier, when a magnetic resonance signal emitted by a human body induces a weak radio frequency current in the radio frequency circuit, two ends of the signal feed-in point capacitor C4 generate a corresponding radio frequency signal voltage, and the voltage is very weak, so that the voltage needs to be amplified by the preamplifier and then output to a magnetic resonance system. Capacitor C4 also acts as an impedance match so its capacitance is not arbitrarily sized and it is necessary to match the impedance of the coil path to the optimum noise source impedance of the preamplifier where the noise figure of the entire coil is at its lowest. As mentioned above, the capacitors C1, C2, C3 and C4, together with the inductance formed by the conductors connecting these capacitors, form a resonant circuit for detecting the magnetic resonance signal emitted from the human body, and the resonant frequency needs to be tuned to be close to the frequency of the magnetic resonance signal in order to improve the detection efficiency.

Since the magnetic resonance radio frequency coil usually has a plurality of channels, and the channels are coupled with each other severely, the input impedance of the current preamplifier is usually very low, and C4, L2 and impedance matching inductors C9 and L3 located in the preamplifier are adjusted to the frequency of the magnetic resonance system, so that a very large parallel resonance impedance can be generated at both ends of C4, thereby the radio frequency loop of the coil is in a high impedance state, and the coupling between the channels is reduced.

In this way, if the preamplifier is placed in the upper half of the coil, the amplified signal is transmitted to the lower half of the coil using 11 pairs of coaxial connectors and output to the magnetic resonance system via the system cable in the lower half. If the preamplifier is placed in the lower half of the coil, it is also necessary to use 11 pairs of coaxial connectors to transmit the unamplified signal to the preamplifier in the lower half.

While it is well known that the cost of a nonmagnetic connector, particularly a coaxial connector, is high, so many connectors will significantly increase the material cost of the coil. Moreover, with such a large number of connectors, the insertion and extraction forces can be large, so that both the fastening and the opening of the coil can be laborious, and the user experience can be poor. More importantly, if there is a problem with such many connectors, the coil will fail, or even fail to scan properly, and the reliability of the coil will be very poor.

In the present invention, the preamplifier for the channel located in the upper half 5 is placed entirely in the lower half 6 of the coil. An inductor L1 is connected in series in the rf loop of the upper part 5, which is responsible for detecting the mr signal, as a signal feed point. The input of the preamplifier 3 in the lower half 6 is connected to another inductor two L5, which has mutual inductance coupling. When the human body emits the magnetic resonance radio frequency signal, an rf voltage is induced in the rf loop of the coil, and a certain rf current is generated in the inductor L1. Because the two inductors (L1 and L5) are mutually coupled, a certain radio frequency voltage can be induced at two ends of the inductor two L5 positioned at the lower half part 6, and the voltage is directly input to the preamplifier positioned at the lower half part, amplified and output to the magnetic resonance system through the system cable.

As shown in fig. 1, the signal feed point capacitance C4 also acts as an impedance match, whereas in embodiments of the present invention, if the coil is operated at 1.5T, the capacitance of this capacitance is typically in the range of 50pF-150 pF. Similarly, with inductive coupling, this mutual inductance also needs to function as both signal feed and impedance matching, so it is usually required to be between 40nH and 120 nH.

Since the loss of the inductor is usually larger than the loss of the capacitor, the introduction of the extra inductor will result in the decrease of the signal-to-noise ratio of the coil. In order to reduce the loss of the inductors as much as possible, the coupling coefficient of the two inductors needs to be increased as much as possible, so that the loss of the two inductors can be reduced as much as possible. For this purpose, the two inductors need to be as close together in space as possible. As shown in fig. 3, the outer edges of the upper and lower halves of the coil generally have a plane, which is the position of the connector, and the outer sides of the planes are substantially coincident when the upper and lower halves are fastened together. The two inductors can be made into a plane spiral shape and respectively placed on the edge planes of the upper half part and the lower half part, and the same position of the upper part and the lower part is ensured. The two inductances are thus spatially closest, the coupling efficiency of which is at most high. Since the wall thickness of the coil housing is usually 2-4mm, the distance between the two inductors is usually 4-8mm theoretically, and it is of course necessary to consider that some gaps are always formed in the middle during actual fastening, but the gaps are usually not larger than 1 mm. The distance between the two inductors can be adjusted, if necessary, by suitably changing the wall thickness of the housing where the inductors are placed.

When two 4-turn planar spiral inductors with an inner diameter of 1cm and an outer diameter of 3cm are vertically separated by 6mm, the mutual inductance is about 120 nH. This is sufficient to improve the channel isolation in almost all cases.

In addition, as mentioned above, the preamplifier needs to play a role of improving the isolation of each channel of the coil, so when the two ends of the inductor in the lower half part are connected with the input end of the preamplifier, a capacitor two C11 needs to be connected in series. In order to improve the isolation between the channels of the coil, the inductor two L5, the capacitor two C11 and the capacitor C10 and the inductor L4 of the matching circuit inside the preamplifier 3 resonate at the frequency of the magnetic resonance system. Since the coil resonant circuit is connected in series with an inductor for signal feeding, a capacitor-C6 is usually connected in series to cancel the inductive reactance of the inductor.

Thus, a circuit originally connected together is divided into two independent circuits located in different spaces, and respectively comprises two resonant circuits, namely a resonant circuit I1 located in the upper half portion 5 and responsible for detecting signals and a resonant circuit II 2 located in the lower half portion 6, the two resonant circuits are mutually inductively coupled through two inductors I1 and two inductors I5, and magnetic resonance signals detected by the resonant circuit I1 located in the upper half portion 5 are coupled and transmitted to the preamplifier 3 located in the lower half portion 6 for amplification, and are transmitted to a magnetic resonance system through a system cable located in the lower half portion 6.

In this way, the signal can be fed from the resonant tank of the channel in the upper half to the preamplifier in the lower half without using a coaxial connector.

The system cable of the coil in the above-mentioned embodiment is in the lower half of the coil, and some coils may be in the upper half, so that the same idea and method can be used, only the preamplifier is placed in the upper half, and the signal of the coil channel in the lower half is coupled to the preamplifier 3 in the upper half by using mutual inductance coupling.

The utility model can also be used with some channels, still using conventional connector means.

In practical use, in a resonant loop of a coil responsible for detecting a signal, a detuning circuit is also needed, and if an active detuning circuit is used, a driving voltage needs to be provided for a PIN diode of the detuning circuit.

Claims

1. A magnetic resonance radio frequency coil structure for replacing a connector comprises an upper coil part and a lower coil part, and is characterized in that: the upper part sub-coil comprises a first resonant circuit and a first inductor, and the first resonant circuit (1) is connected with the first inductor (L1) in series; the lower part coil comprises a second resonance loop, a second inductor and a preamplifier, wherein the second resonance loop (2) is connected with the preamplifier (3), and the second inductor (L5) is connected between the second resonance loop (2) and the preamplifier (3) in series.

2. A connector-substituted magnetic resonance radio frequency coil structure as set forth in claim 1, wherein: and a first capacitor (C6) is connected in series between the first resonant loop (1) and the first inductor (L1).

3. A connector-substituted magnetic resonance radio frequency coil structure as set forth in claim 1, wherein: and two ends of the second inductor (L5) are connected with the input end of the preamplifier (3).

4. A connector-substituted magnetic resonance radio frequency coil structure as claimed in claim 1 or 3, wherein: and a second capacitor (C11) is connected between the second inductor (L5) and the preamplifier (3) in series.

5. A connector-substituted magnetic resonance radio frequency coil structure as set forth in claim 1, wherein: the first inductor (L1) and the second inductor (L5) are close to each other, and effective mutual inductance coupling is formed.

6. A connector-substituted magnetic resonance radio frequency coil structure as set forth in claim 1, wherein: the first inductor (L1) and the second inductor (L5) are planar spiral inductors.

7. A connector-substituted magnetic resonance radio frequency coil structure as set forth in claim 1, wherein: the outer sides of the upper branching coil and the lower branching coil are respectively provided with a plane in a connected mode, and a first inductor (L1) and a second inductor (L5) are respectively arranged in the upper plane and the lower plane.

8. A connector-substituted magnetic resonance radio frequency coil structure as claimed in claim 5 or 7, wherein: the distance between the first inductor (L1) and the second inductor (L5) is 4-8 mm.