High-frequency coil system for magnetic resonance imaging

Abstract

A high-frequency coil system for a magnetic resonance imaging system is provided, comprising a main coil element and a number of secondary coil elements, wherein the main coil element and secondary coil elements are adapted to receive high-frequency signals, and each of the main coil element and secondary coil elements is provided with connectors adapted to connect the secondary coil elements to and / or to each other, and the high-frequency signals received by each secondary coil element are transmitted to the main coil element directly or via one or more secondary coil elements, and the main coil element is provided with a data interface adapted to make a data connection to the magnetic resonance imaging system in order to transmit the high-frequency signals received from the secondary coils to the magnetic resonance imaging system. In this way, a high-frequency coil system with improved signal transmission is provided.

Description

Technical Field

[0001] The present invention relates to the field of magnetic resonance imaging. In particular, the present invention relates to the field of high-frequency coil systems for magnetic resonance imaging.

Background Art

[0002] Part of all magnetic resonance imaging devices is a high-frequency coil for receiving a magnetic resonance signal which is a high-frequency signal. The high-frequency coil includes a fixed array of high-frequency coil elements arranged to cover the surface of a patient. The high-frequency signal of each coil element is amplified and digitized separately using a downstream preamplifier and an AD converter. The high-frequency coil, the preamplifier, and the analog / AD converter form a high-frequency antenna system. In magnetic resonance imaging, a system-integrated body coil generates an excitation magnetic field for a spin system. The precession motion of the net magnetization induces a current in the high-frequency coil via electromagnetic induction. The high-frequency coil generally includes a wire having inductance and coil resistance. Similar to any high-frequency operating system, the high-frequency antenna system is subject to noise. Thereby, the most important requirement is to achieve a minimum noise figure. The lowest noise figure is achieved when the source impedance is matched to the noise impedance of the preamplifier. The signal-to-noise ratio depends on the patient's geometry, the bore size, and the relative position of the high-frequency coil within the bore. This means that the signal-to-noise ratio cannot be maintained at a constant level since it depends on the patient, the high-frequency coil used, and the position of the coil on the patient.

[0003] Since the signal-to-noise ratio depends on the distance between the high-frequency coil and the patient, it is important to conform the high-frequency coil to the body as much as possible. This is particularly difficult for larger coils that cover a larger body surface area due to the heterogeneity of the patient's body. Therefore, magnetic resonance imaging sites generally consist of assemblies of different high-frequency coils of different sizes and shapes. Most high-frequency coils have a large number of fixed coil elements (8 to 16) and are relatively bulky. There can be various different coils with 4, 6, 8, 12, or 16 fixed coil elements all present in a single magnetic resonance imaging site, each used for patients of different sizes and different body parts. Adjacent coil elements are mainly inductively coupled to each other. If each coil element is separately tuned to the magnetic resonance frequency and matched to the input impedance of the preamplifier, the mutual coupling between elements generates coupled modes, which causes spectral splitting of the coil. As a result, the high-frequency coil is detuned and again becomes mismatched, causing a decrease in the signal-to-noise ratio. In addition, their sensitivity profiles overlap, causing image artifacts and reducing the scan time in parallel imaging. To maintain the signal-to-noise ratio of the element and to make optimal use of the parallel image, the coil element needs to be disconnected again.

[0004] Standard decoupling for fixed coil elements is performed by connecting the coil outputs with an appropriate decoupling network. The layout and dimensions of these networks depend on the mutual inductive coupling between the coil elements, which is determined primarily by their relative spatial arrangement. The relative spatial arrangement of individual coil elements is largely fixed in conventional high-frequency coils. Therefore, fixed decoupling networks can be used.

[0005] Various conventional high-frequency coils occupy a significant amount of space in magnetic resonance imaging systems. They are not easy to use, and if even one element fails, the entire high-frequency coil must be replaced. As a result, the body part in question can no longer be examined with the corresponding high-frequency coil due to the failure of a single high-frequency coil element. Furthermore, even if dedicated high-frequency coils are used for individual body regions, the distance between the high-frequency coil and the patient surface becomes very large, reducing the signal-to-noise ratio only due to differences between patients.

[0006] Yeh JNT et al., “A Flexible and Modular Receiver Coil Array for Magnetic Resonance Imaging” (IEEE Transactions on Medical Imaging, 38(3), 824–833, 2019), describes a system of high-frequency coils based on several wired quad coils that can be arranged in close proximity to each other on a regular grid so that a specified distance and element overlap provides decoupling. Each quad coil is wired by itself, and two sets of quad coils must always be used together. Modular, expandable high-frequency coils often have the disadvantage that each high-frequency coil element must be wired individually and at least two coil elements must be used, resulting in an increased possibility of interference and increased susceptibility to failure in these modular systems. [Overview of the project] [Problems that the invention aims to solve]

[0007] The object of the present invention is to provide a high-frequency coil having improved signal transmission. [Means for solving the problem]

[0008] According to the present invention, this objective is addressed by the subject matter of the independent claim. Preferred embodiments of the present invention are described in the dependent claims.

[0009] Accordingly, the present invention provides a high-frequency coil system for a magnetic resonance imaging system comprising a main coil element and a number of secondary coil elements, wherein the main coil element and secondary coil elements are adapted to receive high-frequency signals, the main coil element and secondary coil elements each include a connector adapted to connect the secondary coil elements to and / or to each other, the high-frequency signals received by each secondary coil element are transmitted directly to the main coil element or via one or more secondary coil elements, respectively, and the main coil element includes a data interface adapted to make a data connection to a magnetic resonance imaging system for transmitting high-frequency signals received from the secondary coil elements to the magnetic resonance imaging system.

[0010] The main coil elements have a data interface designed to transmit high-frequency signals to a magnetic resonance imaging (MRI) system. The secondary coil elements, on the other hand, are connected to each other and / or to the main coil elements so that high-frequency signals received by each secondary coil element or main coil element can be transmitted to the MRI system via the data interface. This allows, for example, in the case of a wired connection between the main coil elements and the MRI system, only the main coil elements to be connected to the MRI system. The secondary coil elements do not need to be connected in this way, which makes handling the MRI system much easier, reduces potential failures, and allows for greater flexibility in positioning the MRI system. Thus, the high-frequency signals transmitted to the MRI system can be transmitted to the MRI system via cable or wirelessly using the data interface.

[0011] The modular design of the high-frequency coil system has the special advantage that the high-frequency system formed by the main coil element is suitable for any imaging entity. For example, abdominal imaging can be performed using a high-frequency coil system that covers the upper part of the patient's body. Similarly, with the same system, fewer secondary coil elements can be used compared to abdominal imaging; the ankle or shoulder can be examined without requiring a dedicated shoulder or joint high-frequency coil. In particular, with respect to smaller magnetic resonance imaging sites, they can perform different imaging using the high-frequency coil system according to the present invention, without the need for a dedicated space-consuming high-frequency coil for each imaging entity, which also represents a considerable cost factor.

[0012] At the same time, a high degree of compatibility is achieved with respect to the attachment of the high-frequency coil system to the patient. Here, the phrase "attached to the patient" means that the high-frequency coil is positioned relative to the patient within the opening of the magnetic resonance imaging apparatus. Advantageously, the high-frequency coil may be positioned on the patient's body surface to reduce signal transmission through the air. This results in a higher signal-to-noise ratio due to the short distance between the high-frequency coil system of the present invention and the patient's surface.

[0013] Another advantage of the high-frequency coil system according to the present invention is that it essentially functions even if a defect occurs in the secondary coil element or the main coil element. The defective element must be replaced and repaired, but the functionality of the other elements remains, and therefore there is no need to stock duplicates of the entire high-frequency coil, such as the head coil. Rather, only individual coil elements need to be available as replacements.

[0014] In addition, the daily clinical routine performed by the system according to the present invention is significantly simplified, particularly in terms of the effort required for cleaning and the ability to automate the cleaning of coil elements.

[0015] Preferably, the main coil element and secondary coil element are formed such that multiple secondary coil elements can be directly connected to the main coil element and are provided with connectors. Each of the main coil element and secondary coil element may comprise one or more coils for receiving high-frequency signals. Similarly, several main coil elements can be permanently connected adjacent to each other, in which case each of these main coil elements can be connected to several secondary coil elements.

[0016] In principle, secondary coil elements can be designed in different ways. However, according to a preferred embodiment of the present invention, the secondary coil elements include at least one first group of secondary coil elements that are all identical. In this case, it is preferable that the secondary coil elements have the same size and shape. In this regard, it is preferable that the main coil elements also have the same shape and size as the secondary coil elements. This makes it possible to connect the secondary coil elements to each other in a homogeneous grid so that one secondary coil element is spaced equally apart from another.

[0017] According to a preferred embodiment of the present invention, the secondary coil elements comprise a second group of secondary coil elements, all identical in size and shape, such that a single secondary coil element from the second group can replace multiple single secondary coil elements from the first group. This means that the secondary coil elements from the first group are smaller than those from the second group, and that instead of using multiple secondary coil elements from the first group, one coil element from the second group can be used. Thus, a single coil element from the second group covers essentially the same area as a combination of multiple secondary coil elements from the first group connected to each other. However, the covering area may not be 100% identical due to rounded corners, etc. For example, if the connection of the secondary coil elements from the first and second groups is considered to be a grid with basic grid elements having a certain area, then a secondary coil element from the first group can cover a single grid element, and a secondary coil element from the second group can cover two grid elements.

[0018] In principle, the main coil elements and the secondary coil elements can have different shapes. However, preferably, the main coil elements and secondary coil elements are rectangular. More preferably, the main coil elements and secondary coil elements are square or rhombic. By having all four sides or boundaries of the square or rhombic shape be of the same length, the secondary coil elements can be connected to each other or to the main coil elements on all four sides, thereby making it possible to form a homogeneous grid around the main coil elements and the connected secondary coil elements. Several square main coil elements can be mounted together; for example, four main coil elements can be arranged in a square and connected to each other, so that each main coil element has three boundaries to which secondary coil elements can be connected.

[0019] Connectors can be designed in different ways. However, according to a preferred embodiment of the present invention, the connector is a coaxial contact between an inner conductor and an outer conductor, the inner conductor being adapted to transmit a received high-frequency signal, and the outer conductor forming a shield for the inner conductor. In particular, the connector is configured in the type of coaxial cable. The outer conductor shields the inner conductor transmitting the received high-frequency signal from electromagnetic interference. This makes it possible to reduce the effect of electromagnetic interference on the received high-frequency signal.

[0020] According to a particularly preferred embodiment of the present invention, the outer conductor is also adapted to mechanically fasten one connector to another. The principle of a snap fastener is preferably used here. In this regard, there are preferably two different types of connectors designed as a connector head and a connector immersion, the connector head being formed to be connectable to the connector immersion, the inner conductor being positioned at the center of the connector head and the center of the connector immersion, and the outer conductor surrounding the inner conductor in a ring shape so that the outer conductor of the connector head and the outer conductor of the connector immersion are in contact with each other and act as a shield that contacts the inner conductor when the connector head and the connector immersion are connected to each other. The connector head is then positioned correspondingly above or below the coil elements. The connector immersion is then positioned correspondingly to the bottom or top surface of each of the further coil elements so that the coil elements can be brought into contact with each other without the need to invert the coil elements. These connectors are fixed in position relative to the edge of each coil element so that the coil elements are arranged at equal intervals. In contrast to rotation, which represents a rotation around a normal vector perpendicular to the surface of the coil, inversion of a coil element means a rotation perpendicular to the normal vector perpendicular to the surface of the coil element. Here, when referring to coil elements, both secondary and primary coil elements are meant.

[0021] In principle, connectors can be arranged on secondary coil elements in various ways. However, according to a preferred embodiment of the present invention, each secondary coil element has a first connector on a first boundary, the first connectors are arranged equidistant from each other along a straight line, and each secondary coil element has a second connector on a second boundary, the second boundary is opposite to the first boundary, the second connectors are arranged equidistant from each other along a straight line at the same distance as the first connectors, and a plurality of feedthrough lines are provided, each feedthrough line is positioned between one of the first connectors and one of the second connectors respectively to transmit a received high-frequency signal between each of the first connectors and each of the second connectors, and each feedthrough line connects the first connector to such second connector which is offset by only one position relative to the first connector along a straight line.

[0022] This allows high-frequency signals received by secondary coil elements to be transmitted to primary coil elements via their respective feedthrough lines. Therefore, the number of connectors on one boundary of a primary coil element determines the maximum number of secondary coil elements that can be connected to that boundary of the primary coil element, since each high-frequency signal received by a secondary coil element is transmitted to the primary coil element via its respective feedthrough line.

[0023] In principle, it may be provided that the high-frequency signals received by the secondary coil elements are receivable by different connectors. However, according to a preferred embodiment of the present invention, the first or second connector is not mounted on a feedthrough line located between the first and second connectors, but includes an initial connector mounted on a transmission line adapted to supply the high-frequency signals received by each secondary coil element to the initial connector.

[0024] Preferably, the number of first connectors and the number of second connectors differ by one. The boundary of a secondary coil element facing a main coil element is a boundary of a secondary coil element having one or more connectors than the opposing boundary. In this way, the high-frequency signals of the initial connectors of each secondary coil element are always picked up by further connected secondary coil elements and transmitted to the main coil element in the corresponding feedthrough lines.

[0025] Furthermore, these secondary coil elements may include feedthrough lines offset from the feedthrough lines connecting the first and second boundaries. Rectangular secondary coil elements generally have third and fourth boundaries, thereby comprising a third connector and a fourth connector, also arranged linearly at equal distances from each other, which are connected via feedthrough lines in the same way as the first and second connectors, so that each high-frequency signal received by the secondary coil element can be transmitted to the main coil element via their respective feedthrough lines. The third and fourth connectors are not connected to the feedthrough lines located between the third and fourth connectors, but include an initial connector connected to a transmission line adapted to deliver high-frequency signals received from each secondary coil element to the initial connector. In the case of a square secondary coil element, the third connector located at the third boundary, the fourth connector located at the fourth boundary, and the feed-through line connecting the third and fourth connectors are rotated 90 degrees relative to the first connector located at the first boundary, the second connector located at the second boundary, and the feed-through line connecting the first and second connectors. This allows further secondary coil elements to be connected to the third and fourth boundaries of the secondary coil element.

[0026] Alternatively, the third and fourth boundaries may each have a third connector and a fourth connector connected to the first connector of the first boundary by a feed-through line, similar to the second connector of the second boundary. As a result, the second connector of the second boundary, the third connector of the third boundary, and the fourth connector of the fourth boundary route high-frequency signals to the first connector of the first boundary using their respective feed-through lines. Thus, on the one hand, there can be a secondary coil element that can transfer high-frequency signals coming in from two boundaries to two boundaries accordingly. On the other hand, there may be a secondary coil element that can transfer high-frequency signals from three boundaries to one boundary.

[0027] The transmission of high-frequency signals of the secondary coil elements of the second group of secondary coil elements is performed such that one connector remains unused for signal transmission so that the correct order of the high-frequency signal feed-through lines is maintained. This design ensures that the high-frequency signals of the secondary coil elements of the second group are directed to the corresponding connectors of the secondary coil elements of the first group.

[0028] To ensure that the received high-frequency signals are transmitted with as little noise as possible, appropriate high-frequency trapping can also be used to filter out the common-mode current generated in the high-frequency transmission line by the magnetic resonance imaging system. If there is a long radio frequency transmission line inside or near the aperture of the magnetic resonance imaging device, the bore needs to be equipped with means for suppressing the high-frequency induced common-mode current. Otherwise, image artifacts or patient burns may occur. In particular, when the length of the high-frequency transmission line approaches resonance, a significant amount of high-frequency power can be extracted. Preferably, this high-frequency trapping forms an inductance and a capacitor is connected in parallel to each feed-through line, and a tank circuit is provided at least in part of the feed-through line of each secondary coil element.

[0029] In the alternative embodiment, it is preferable that at least some of the through - line portions of the secondary coil element are each provided with a floating cable trap disposed on each through - line and inductively coupled thereto. A floating - type cable trap does not require a physical connection to the through - line. The floating cable trap can consist of two coaxial concentric conductive cylinders, one end of which is short - circuited to each other and the other end is tuned to resonance.

[0030] Basically, the pre - amplifier does not need to be included in the high - frequency coil system. The pre - amplifier can also be included in the magnetic resonance imaging system and can receive the high - frequency signal output from the main coil element. However, according to a preferred embodiment of the present invention, each secondary coil element is provided with a pre - amplifier for pre - amplifying the high - frequency signal before transmitting the high - frequency signal to another secondary coil element or the main coil element. Thereby, costly noise matching can be prevented. The impedance of each through - line can already be amplified immediately after being received by each secondary coil element using each pre - amplifier, so it does not affect the received high - frequency signal to be amplified.

[0031] According to a preferred embodiment of the present invention, the main coil element is provided with a pre - amplifier, and each pre - amplifier is respectively assigned to one single secondary coil element for pre - amplifying the high - frequency signal received from each secondary coil element. For this purpose, it can be provided that the pre - amplifier is designed in the form of a pre - amplifier array within a modular scalable array, or that the pre - amplifier has several channels capable of realizing a pre - amplifier array within a modular scalable array. The pre - amplifier array is then connected to the main coil element and disposed on a connector having a number of channels corresponding to the maximum number of coil elements, so that, depending on the secondary coil elements connected to the main coil element, pre - amplifier channels are available for high - frequency signal pre - amplifiers for each received high - frequency signal.

[0032] According to a further preferred embodiment of the present invention, each preamplifier is provided with a matching circuit, or each secondary coil element is provided with a matching circuit for noise matching to its respective preamplifier. When all preamplifiers are included in the main coil element, the conductor impedance of each secondary coil element changes depending on the number of chained secondary coil elements as the length of the feedthrough line changes. Thus, each preamplifier is noise-matched, preferably for each secondary coil element configuration. Preferably, the matching circuit has at least two modes that can be switched by a gallium nitride (GaN) switch. According to this embodiment of the present invention, all preamplifiers are included in the main coil element, and unamplified high-frequency signals are routed to the main coil element through the secondary coil element.

[0033] In principle, controllers can be formed within a magnetic resonance imaging system in various ways. However, according to a preferred embodiment of the present invention, the high-frequency coil system further comprises a controller which identifies secondary coil elements connected to each main coil element and is adapted to adjust the matching circuit. When an additional secondary coil element is connected to a main coil element or further secondary coil elements, this new connection is automatically established. The new connection also triggers automatic high-frequency decoupling of the new element from all adjacent secondary elements and / or main coil elements. This is possible because the decoupling electronics implemented in the controller can be pre-adjusted by utilizing known relative geometric shapes, the distance between each coil element, and their known sizes. Identification of additional coil elements and correct assignment of coil impedance to preamplifiers can be performed by different methods such as optical or galvanic signaling or digital keying. Identification of impedance and feedthrough line length can be achieved by short-voltage pulse detection performed before the image.

[0034] Furthermore, the present invention provides a magnetic resonance imaging apparatus equipped with a high-frequency coil system as described in any one of the claims.

[0035] The present invention further relates to a method for operating a high-frequency coil system for a magnetic resonance imaging system comprising a main coil element and a number of secondary coil elements connected to the main coil element or to each other, the method comprising the steps of: receiving a high-frequency signal using at least the secondary coil elements; transmitting the high-frequency signals received by each secondary coil element directly to the main coil element or via one or more secondary coil elements; establishing a data connection from the main coil element to the magnetic resonance imaging system; and transmitting the high-frequency signals received from the secondary coil elements to the magnetic resonance imaging system via the data connection. This connection may be wired or wireless.

[0036] According to a preferred embodiment of the present invention, the method further includes the steps of identifying secondary coil elements connected to each main coil element and controlling at least one matching circuit for adjusting the impedance values ​​of the high-frequency coil system. Each secondary coil element is identified, and its relative position compared to other secondary coil elements is also identified.

[0037] Furthermore, according to the present invention, when performed by a high-frequency coil system for a magnetic resonance imaging system, a computer-readable medium is provided which contains instructions causing the frequency coil system to perform the method according to any one of the claims (the first method being claimed in the last method claim).

[0038] These and other aspects of the present invention are evident from and will be explained with reference to the embodiments described below. Such embodiments do not necessarily represent the entire scope of the present invention. [Brief explanation of the drawing]

[0039] [Figure 1] A schematic diagram of a high-frequency coil system according to a preferred embodiment of the present invention is shown. [Figure 2] A schematic diagram of a connector according to a preferred embodiment of the present invention is shown. [Figure 3a]A schematic diagram of a first high-frequency trap according to a preferred embodiment of the present invention is shown. [Figure 3b] A second high-frequency trap according to a preferred embodiment of the present invention is schematically shown. [Figure 3c] A third high-frequency trap according to a preferred embodiment of the present invention is schematically shown. [Figure 4] Another high-frequency coil system according to a preferred embodiment of the present invention is schematically shown. [Figure 5] A schematic diagram of a secondary coil element according to a preferred embodiment of the present invention is shown. [Figure 6] A schematic outline of a method according to a preferred embodiment of the present invention is shown. [Figure 7] A schematic diagram of a magnetic resonance imaging system according to a preferred embodiment of the present invention is shown. [Modes for carrying out the invention]

[0040] Figure 1 schematically shows a high-frequency coil system 1 according to a preferred embodiment of the present invention. The high-frequency coil system 1 of Figure 1 according to the present invention has a main coil element 2 and secondary coil elements 3 connected to the main coil element 2. The secondary coil elements 3 connected to the main coil element 2 are further connected to another secondary coil element 3. The main coil element 2 is a square with rounded corners. Four connectors are formed in a straight line at equal distances from each other along each boundary of the main coil element 2. The square secondary coil elements 3 also have four connectors formed in a straight line at equal distances from each other along the boundaries of the secondary coil elements, similar to the main coil element 2.

[0041] In alternative embodiments, the main coil element and secondary coil element may have other geometric shapes (e.g., rectangle, triangle, rhombus, etc.), as long as each has complementary connectors configured to connect the main coil element to one or more secondary coil elements and to connect the multiple secondary coil elements to each other. Additionally or alternatively, all embodiments of the main coil element and secondary coil element may have fewer than four or more connectors, which may be formed by equidistant straight lines or other relative positioning and variable distances, as long as the connectors of the main coil element and secondary coil element are provided in corresponding settings to ensure proper connection of the main coil element to one or more secondary coil elements and connection of the multiple secondary coil elements to each other.

[0042] Referring back to Figure 1, the first boundary 24 of the secondary coil element 3 includes four first connectors 4 connected to the main coil element 2 so that it can transmit high-frequency signals. One of the first connectors 4 is designed as an initial connector 4 which can be connected to a further initial connector 4 of the secondary coil element 3 so that a transmission line is formed suitable for supplying the high-frequency signals received from each secondary coil element 3 to the initial connector 4. The first connectors 4 are marked with "x" in Figure 1. The main coil element and the secondary coil element may each include a single coil, e.g., a coil ring, or multiple coils, e.g., multiple coil rings, for transmitting and / or receiving high-frequency signals. Thus, the coil ring can function as a transmitting and / or receiving RF antenna. The initial connectors indicated by "x" are directly connected to the antennas of the respective main coil element or secondary coil element.

[0043] A further first connector 4 on the first boundary 24 is connected to a second connector 6 on the second boundary 26 by a feedthrough line 7 so that a high-frequency signal can be transmitted from the second connector 6 to the first connector 6. The second boundary 26 is located on the opposite side of the first boundary 24. A high-frequency signal received by the further secondary coil element 3 is transmitted to the second connector 6 on the second boundary 26 of the secondary coil element 3 via the initial connector 4 on the first boundary 24 of the further secondary coil element 3, which is also marked with an "x" on the further secondary coil element 3. The high-frequency signal is then transmitted towards the first connector 4 on the first boundary 24 of the further secondary coil element 3 using the feedthrough line 7 formed between the first connector 4 on the first boundary 24 and the second connector 6 on the second boundary 26, and as a result, the high-frequency signal can be transmitted to the main coil element 2. The second connector 6 to which the high-frequency signal is transmitted is offset by one location or position relative to the first connector 4 along the straight line between the first and second connectors. The straight line referred to here extends perpendicularly to the straight line on which the first connector is positioned.

[0044] Finally, the two further first connectors 4 of the first boundary 24 of the secondary coil element 3 are connected to the second connector 6 by two further feedthrough lines 7, the second connector 6 also offset from the first connector 4 by one position or location along the straight line between the first and second connectors. This continuous offset and the cascaded connection formed thereby makes it possible for up to four secondary coil elements 3 to be connected in series in the particular case of four connectors on one boundary of the main coil element 2, in the feedthrough lines 7 which are continued in another secondary coil element 3, and for high-frequency signals received in each secondary coil element 3 to be transmitted to the main coil element 2 via the corresponding feedthrough lines 7.

[0045] In the context of the present invention, the first connector 4 may be referred to as an output port (which outputs RF signals to adjacent coil elements or tiles closer to the control system, or, in the case of a main coil element, directly to the control system or processor), and the second connector 6 may be referred to as an input port (which receives RF signals from adjacent tiles or coil elements far from the control system or processor).

[0046] Each of the secondary coil elements 3 shown in Figure 1 also has third and fourth boundaries. The third boundary is similar to the first boundary 24, and the fourth boundary is similar to the second boundary 26. A feedthrough line 7 is also formed between the third and fourth boundaries, which connects the corresponding connectors for the purpose of high-frequency signal transmission, similar to the one between the first boundary 24 and the second boundary 26.

[0047] The main coil elements and / or sub-coil elements can be represented as tiles or patches, which can be better associated with the modular concept of a coil assembly formed from one or more main coil elements and one or more sub-coil elements. The matrix material of the tiles or patches may be any polymer material used as a system component of a magnetic resonance system, such as polyurethane foam.

[0048] The feedthrough line 7 may be integrated into or embedded in the tile matrix material in various forms such as strip wires, microstrip wires, twisted pair cables, coaxial cables, or combinations thereof, and as a result, the connection of the feedthrough line to the connector maintains high signal integrity, as shown in Figure 2, for example, and does not pick up noise (disruptive or excessive).

[0049] Figure 2 schematically shows a connector according to a preferred embodiment of the present invention. This connector 4 is designed according to the snap fastener model. An inner conductor 14 is formed at the center of the connector head 20 and the center of the connector recess 22. The inner conductor 14 is configured to transmit high-frequency signals. An outer conductor 16 is separated from the inner conductor 16 and surrounds it in an annular manner. The outer conductor 16 shields the inner conductor 14 so that the high-frequency signals have less electromagnetic interference. The connector head 20 formed by the outer conductor 16 can be mechanically connected to the connector recess 22 in the manner of a snap fastener by applying mechanical pressure to the correspondingly assembled connector 4. Thus, the inner conductors 14 are in contact with each other so that they can transmit high-frequency signals. The outer conductor 16 shields the high-frequency signals from external electromagnetic interference. Thus, the connector 4 is coaxial.

[0050] Figure 3a schematically shows a first high-frequency trap according to a preferred embodiment of the present invention. For this purpose, the feedthrough lines 7 of the secondary coil element 3 are equipped with capacitors 17 designed in parallel with each feedthrough line. In addition, the corresponding feedthrough lines 7 may be looped to form inductance. Specifically, however, the inductance of the coaxial connector 4 is used together with the corresponding capacitors 17 of each feedthrough line 7 to form a tank trap in which common-mode current can be trapped within the feedthrough lines 7. Figure 3b schematically shows another high-frequency trap. The common-mode current is inductively coupled here to each feedthrough line 7 and is arranged coaxially with each feedthrough line 7 but then trapped by two consecutive hollow cylinders that are galvanically separated. This device for each feedthrough line 7 forms a floating cable trap 19. Alternatively, in Figure 3c, a single floating cable trap 19 may be formed with all the feedthrough lines 7.

[0051] Figure 4 schematically shows a further high-frequency coil system 1 according to a preferred embodiment of the present invention, which includes four main coil elements 2 connected to each other so as to form a square. As shown in Figure 7, each main coil element 2 is connected to a further secondary coil element 3 to form a high-frequency coil system 1, which enables the acquisition of large-area magnetic resonance images using a magnetic resonance imaging system. Each main coil element 2 has a matching circuit 28, a preamplifier 30, and a modular scalable array 32. The preamplifier 30 is connected to the matching circuit 28 via the modular scalable array 32. The impedance of the high-frequency signal of each secondary coil element 3 is matched to the impedance of the preamplifier 30 by the matching circuit 28, taking into account the impedance of each secondary coil element 3, the patient's intrinsic impedance, and the impedance included in the length of the feedthrough line 7. The preamplifier 30 is connected to the modular scalable array 32 so as to be able to amplify the impedance-matched high-frequency signals of each secondary coil element 3 and main coil element 2 accordingly. The modular scalable array 32 has a maximum number of channels corresponding to the secondary coil elements 3 and main coil elements 2. Using a controller 36 connected to the main coil element 2, a specific number of secondary coil elements 3 connected to one of the main coil elements 2 can be measured, and as a result, the controller 36 can provide a corresponding number of preamplifier channels 30 in the modular scalable array 32 to their respective feedthrough lines 7 for preamplification.

[0052] Furthermore, as shown in Figure 5, each secondary coil element 3 and / or main coil element 2 is equipped with a matching circuit 28 connected to the preamplifier 30, which allows the high-frequency signals received by each coil element to be directly impedance-matched and amplified by the preamplifier 30.

[0053] Figure 6 schematically shows a plan of a method according to a preferred embodiment of the present invention, in which, in the first step S1a, the secondary coil elements 3 connected to each main coil element are identified. Next, in a further step S1b, a matching circuit 28 for adjusting the impedance value of the high-frequency coil system 1 is controlled. Thirdly, in step S1, the high-frequency signal is received by the secondary coil elements 3 and the main coil element 2. Fourthly, in step S2, the high-frequency signal received by each secondary coil element 3 is transmitted to the main coil element 2 directly or via one or more secondary coil elements 3. In a further step S3, a data connection is established from the main coil element 2 to the magnetic resonance imaging system 38, and the high-frequency signal received from the secondary coil elements 3 may be transmitted to the magnetic resonance imaging system 38 via the data connection in step S4.

[0054] Although the present invention is illustrated and described in detail in the drawings and the foregoing description, such illustrations and descriptions should be considered illustrative or non-limiting, and the present invention is not limited to the disclosed embodiments. Other variations of the disclosed embodiments can be understood and achieved by those skilled in the art in carrying out the claimed invention from the study of the drawings, disclosure and the appended claims.

[0055] It is understood that one or more of the above-described embodiments of the present invention may be combined, provided that the combined embodiments are not mutually exclusive. As will be understood by those skilled in the art, aspects of the present invention can be embodied as systems, methods, or computer program products. Accordingly, aspects of the present invention can take the form of entirely hardware embodiments, entirely software embodiments (including firmware, resident software, microcode, etc.), or embodiments combining software and hardware embodiments, all of which can be generally referred to herein as “circuits,” “modules,” or “systems,” and further, aspects of the present invention can take the form of computer program products embodied in one or more computer-readable media having computer executable code embodied thereon.

[0056] The features described above are applicable to embodiments of the system, and corresponding embodiments of the method having similar advantages are also contemplated.

[0057] In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite articles “a” or “an” do not exclude the plural. The mere fact that certain means are described in different dependent claims does not imply that combinations of these means cannot be used advantageously. No reference numeral in the claims should be construed as limiting in scope. Furthermore, for clarity, not all elements in the drawings are denoted by reference numerals. [Explanation of symbols]

[0058] High-frequency coil system 1 Main coil element 2 Secondary coil element 3 First connector, output port 4 Second connector, input port 6 Feed-through line 7 Internal conductor 14 Outer conductor 16 Capacitor 17 Floating cable trap 19 Connector head 20 Connector immersion section 22 First boundary 24 Second boundary 26 Matching circuit 28 Preamplifier 30 Modular Scalable Array 32 Controller 36 Magnetic resonance imaging apparatus 38

Claims

1. A high-frequency coil system for a magnetic resonance imaging system, It comprises a main coil element and numerous secondary coil elements, The main coil element and the secondary coil element are adapted to receive high-frequency signals. The main coil element and the secondary coil element each include a connector adapted to connect the secondary coil element to and / or to each other, and the high-frequency signals received by each secondary coil element are transmitted directly to the main coil element or via one or more secondary coil elements, respectively. The main coil element has a data interface adapted to make a data connection to the magnetic resonance imaging system so as to transmit high-frequency signals received from the secondary coil element to the magnetic resonance imaging system. Magnetic resonance imaging system.

2. The high-frequency coil system according to claim 1, wherein the secondary coil elements have a first group of secondary coil elements that are all identical.

3. The high-frequency coil system according to claim 2, wherein all of the secondary coil elements are identical, and the system has a second group of secondary coil elements having a size and shape such that a single secondary coil element of the second group can replace multiple single secondary coil elements of the first group.

4. The high-frequency coil system according to any one of claims 1 to 3, wherein the connector comprises a coaxial contact portion between an inner conductor and an outer conductor, the inner conductor being adapted to transmit a received high-frequency signal, and the outer conductor forming a shield for the inner conductor.

5. The high-frequency coil system according to claim 4, wherein the outer conductor is adapted to mechanically secure one connector to the other connector.

6. Each secondary coil element is provided with a first connector on a first boundary, and the first connectors are arranged along a straight line and at equal distances from each other. Each secondary coil element is provided with a second connector on a second boundary, the second boundary facing the first boundary, and the second connectors are arranged equidistant from each other along a straight line and at the same distance as the first connectors. Multiple feedthrough lines are provided, and each feedthrough line is positioned between one of the first connectors and one of the second connectors to transmit the received high-frequency signal between each first connector and each second connector. Each feedthrough line connects the first connector to a second connector which is offset by one position relative to the first connector along the straight line. A high-frequency coil system according to any one of claims 1 to 5.

7. The high-frequency coil system according to claim 6, wherein the first connector or the second connector is an initial connector, the initial connector is not attached to a feedthrough line located between the first connector and the second connector, but is attached to a transmission line adapted to supply high-frequency signals received by each secondary coil element to the initial connector.

8. The high-frequency coil system according to any one of claims 1 to 7, wherein each secondary coil element is provided with a preamplifier for preamplifying the high-frequency signal before transmitting the high-frequency signal to another secondary coil element or the main coil element.

9. The high-frequency coil system according to any one of claims 1 to 8, wherein the main coil element comprises a preamplifier, and each preamplifier is assigned to a single secondary coil element to preamplify the high-frequency signal received from each secondary coil element.

10. The high-frequency coil system according to claim 9, wherein each preamplifier is provided with a matching circuit, or each secondary coil element is provided with a matching circuit for noise matching each preamplifier.

11. The high-frequency coil system according to any one of claims 1 to 10, further comprising a controller, the controller being adapted to identify the secondary coil elements connected to each main coil element and thereby adjust the matching circuit.

12. A magnetic resonance imaging apparatus comprising a high-frequency coil system according to any one of claims 1 to 11.

13. A method for operating a high-frequency coil system for a magnetic resonance imaging system, comprising a main coil element and a number of secondary coil elements connected to the main coil element or to each other, wherein the method is: The steps include receiving a high-frequency signal using at least one of the secondary coil elements, The steps include transmitting the high-frequency signals received by each secondary coil element directly to the main coil element, or via one or more secondary coil elements, respectively. The steps include: connecting data from the main coil element to the magnetic resonance imaging system; The steps include: transmitting the high-frequency signal received from the secondary coil element via the data connection to the magnetic resonance imaging system; A method having

14. The steps include identifying the secondary coil elements connected to each main coil element, The steps include controlling at least one matching circuit for adjusting the impedance value of the high-frequency coil system, and The method according to claim 13, further comprising:

15. A computer-readable medium having instructions that cause a high-frequency coil system to perform the method according to any one of claims 13 to 14, when performed by the high-frequency coil system for a magnetic resonance imaging system.

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