Radio frequency coil placement in magnetic resonance imaging devices

Abstract

The present invention relates to a system 1 for magnetic resonance imaging, comprising a magnetic resonance imaging device 2 and a control unit 3 for controlling the magnetic resonance imaging device 2, wherein the magnetic resonance imaging device 2 comprises a magnetic resonance bore 4, a movable table 5 movable in and out of the magnetic resonance bore 4, and at least two coil elements 15 of at least one coil 7, the two coil elements 15 being arranged adjacent to each other on the movable table 5 to have a relative overlap R, the at least one coil 7, 24 comprising an outer cover 25 and an inner core 26, the inner core 26 comprising at least two coil elements that slide laterally two-dimensionally within the outer cover 25, and the control unit 3 comprises a coil element detection unit 31 for detecting the at least two coil elements 15, an overlap detection unit 32 for detecting the relative overlap R of the at least two coil elements 15, a determination unit 33 for determining whether the detected relative overlap R is within a predetermined critical range, and a position adjustment unit 34 for adjusting the relative positions of the coil elements 15 if the detected relative overlap R is outside the critical range. The invention further relates to a method 100 and a program element for producing an image by magnetic resonance imaging.

Description

[Technical Field]

[0001] The present invention relates to a system for magnetic resonance imaging, a method for producing images by magnetic resonance imaging, and a program element. [Background technology]

[0002] High patient throughput is important for magnetic resonance imaging devices, especially in healthcare facilities, so ensuring a smooth imaging process is especially important.

[0003] Radio-frequency coils are commonly used in magnetic resonance imaging devices. Radio-frequency coils are configured to excite magnetization by broadcasting radio-frequency power and receive signals from the excited spins. Therefore, the radio-frequency coil directly affects the spatial and temporal resolution, sensitivity, and uniformity of magnetic resonance imaging. Therefore, correct placement of the receiver coil is crucial to achieving good image quality. Therefore, only trained and experienced staff are typically allowed to operate magnetic resonance imaging devices. For example, staff shortages due to sick leave or holidays, and / or operation of magnetic resonance imaging devices by inexperienced staff, can lead to cancellations and / or delays of planned schedules. Therefore, workflows are becoming increasingly autonomous and automated, making correct coil placement particularly important. Summary of the Invention [Problem to be solved by the invention]

[0004] Wireless radio frequency coil technology offers convenience and ease of operation in coil handling and placement, especially for increasingly autonomous and automated workflows, which, however, pose the challenge of ensuring sufficiently good and consistent image quality. [Means for solving the problem]

[0005] Therefore, there may be a need to improve the arrangement of coils in magnetic resonance imaging devices, especially for autonomous and automated workflows.The object of the present invention is solved by the subject matter of the attached independent claims, with further embodiments incorporated in the dependent claims.

[0006] According to a first aspect, a system for magnetic resonance imaging is provided. The system includes a magnetic resonance imaging device and a control unit for controlling the magnetic resonance imaging device. The magnetic resonance imaging device includes a magnetic resonance bore, a movable table movable in and out of the magnetic resonance bore, and at least two coil elements of at least one coil. The two coil elements are arranged adjacent to each other on the movable table with a relative overlap and are movable relative to each other. The control unit includes a coil element detection unit for detecting the at least two coil elements, an overlap detection unit for detecting the relative overlap of the at least two coil elements, a determination unit for determining whether the detected relative overlap is within a predetermined critical range, and a position adjustment unit for adjusting the relative positions of the coil elements if the detected relative overlap is outside the critical range.

[0007] Such a system for magnetic resonance imaging (MRI) may autonomously detect and guide an optimal relative overlap of at least two coil elements. The optimal relative overlap may be defined as a value within a so-called "critical range," which allows for fast image reconstruction and good image quality. The critical range may be defined by a preset lower limit and a preset upper limit between which uniform B1 sensitivity and a good signal-to-noise ratio may be provided. The predetermined critical range may be stored in a control unit.

[0008] Uniform B1 sensitivity defines the magnetic field sensitivity of the reconstructed image. Magnetic field uniformity is directly proportional to the intensity variation of the image, i.e., the pixel values ​​within the image. Local variations in B1, i.e., variations in pixel values ​​within the image, can lead to undesirable spatially varying image signals and contrast. Therefore, a more uniform B1 sensitivity leads to better image quality.

[0009] A good signal-to-noise ratio can be defined as the independence of noise from different coil elements, which can be achieved within a certain critical range. The signal-to-noise ratio can be determined using the noise correlation matrix.

[0010] Image quality depends on the number of artifacts present. Artifacts can arise due to the patient's breathing and / or blood vessels. Therefore, preventing these artifacts is difficult. Furthermore, artifacts can arise due to an unfavorable signal-to-noise ratio. The signal-to-noise ratio corresponds to the measurable value of the presence and intensity of noise due to undesired signal correlations of adjacently located coil elements. Within a certain critical range, the signal-to-noise ratio approaches an optimal value, minimizing the impact on image quality.

[0011] As used herein, a movable table should be understood as a table or couch on which a patient is placed at least during the magnetic resonance imaging process, and may also be referred to as a patient table. The movable table may include at least one coil, preferably several coils, embedded in the bed surface of the movable table. The embedded coils may be selectively adjusted or detuned by a control unit to achieve an optimal configuration for the imaging process to be performed.

[0012] At least one coil may be a receive coil that is typically placed on the patient's body. Additionally or alternatively, there may be applications in which relative overlap of transmit coils and / or a combination of transmit and receive coils may be applied. A coil may include at least one coil segment including several coil elements. Some coil elements of a coil segment may be pre-positioned relative to one another in a fixed manner so that signal interference between adjacent coil elements is very low and image quality is barely affected.

[0013] At least two coil elements of the at least one coil can be associated with coil elements located in an outer edge region of the at least one coil. The coil configuration can depend on the region to be imaged and / or the individually selected anatomical structure, as well as the size of the coil and / or the size of the patient's body.

[0014] As used herein, the positioning unit should be understood to include audio and / or visual guidance and automatic positioning. In other words, the positioning unit may be configured to support manual adjustment of the coil position, e.g., performed by the patient, by providing audio guidance, e.g., by audio output of positioning instructions, and / or by providing optical guidance, e.g., by displaying the required displacement of the coil, e.g., by indicating the actual position of the coil and the desired position of the coil. Alternatively, or additionally, the positioning unit may be configured to automatically adjust the position of the coil without human intervention. In this case, the coil may have a software-controlled actuator controlled by the positioning unit.

[0015] Furthermore, the control unit, in particular the positioning unit, may be configured to automatically select and detune individual coil elements, in particular wireless radio frequency coils, to bring their relative overlap within a predetermined critical range.

[0016] Thus, the system can enable patient involvement, for example, through autonomous preparation by the patient themselves, without requiring the physical presence of experienced staff. The system can guide the patient through the preparation process, including, for example, selecting the correct coils and positioning the coils so that their relative overlap is within a predetermined critical range.

[0017] In other words, a system for magnetic resonance imaging can increase patient throughput because performance is at least less dependent on the presence of skilled staff. Additionally, the system can improve image quality by adjusting the relative overlap of adjacently positioned overlapping coil elements to a position where the signal-to-noise ratio has little effect on image quality.

[0018] Furthermore, the magnetic resonance imaging device may include a computing unit configured to perform the image generation process, in which case a control unit controlling the magnetic resonance imaging device controls the computing unit to perform the image generation process.

[0019] The control unit may be a state machine capable of machine learning. Machine learning corresponds to a computer-implemented method for accessing and / or collecting data and using the data to learn on its own. Thus, machine learning is an application of artificial intelligence (AI) that allows a system to automatically learn and improve from experience without being explicitly programmed, for example, based on collected data. The control unit may use data from, for example, the coil element detection unit, the overlap detection unit, the determination unit, and / or the position adjustment unit. Furthermore, the control unit may have access to hospital and / or patient databases.

[0020] According to one embodiment, the at least two coil elements may be from different coils. Depending on the application, the use of multiple coils may be required. To ensure seamless imaging, at least two coils may need to be positioned on top of each other. In such cases, the coil elements positioned in the outer edge regions of each coil may be positioned to overlap each other. In the case of only one coil, the coil may be flexible and may be wrapped around a part of the patient's body, such as a knee, and the coil elements in opposing outer edge regions of the coil may be positioned to overlap each other.

[0021] According to further embodiments, at least one coil may have the form of a flat, thin, blanket-like pad. Such a coil may have a flexible shape so that the coil can be wrapped around a portion of the patient's body, as described above. In other applications, such a coil may be placed flat on a portion of the patient's body, such as the lower back, neck, or chest. Additionally, other coil types may be used, such as volume coils or surface coils.

[0022] According to one embodiment, the at least one coil may be wireless or non-wireless.

[0023] A non-wireless coil may include a connecting wire for connecting the coil to either the control unit or the computing unit interface. The non-wireless coil may include two or more coil segments to cover an entire body region; for example, a coil covering the leg may include two coil segments. One coil segment may be configured to be placed on the thigh and the other may be configured to be placed on the lower leg, with both coil segments positioned to overlap each other at the knee. Since all coil segments may be connected to the same connecting wire, such coil segments may be at least partially pre-positioned. A wireless coil may facilitate handling of the coil, especially when placed by an inexperienced person, such as the patient themselves or an operator less skilled in autonomous image acquisition.

[0024] According to one embodiment, the coil element detection unit may comprise at least one sensor configured to detect markers of the coil, the sensor being selected from a 2D sensor group of optical video sensors, capacitive sensors, and inductive sensors, or the sensor being selected from a 3D video sensor group of radar sensors, lidar sensors, and infrared sensors.

[0025] The coils, particularly non-wireless coils, may include optical markers, which may be optical, capacitive, or inductive markers detectable by corresponding sensors in the coil element detection unit. The markers may have predetermined locations on the respective coils such that detection of the markers by the coil element detection unit provides guidance for achieving relative overlap within a predetermined critical range. Additionally or alternatively, the coils, particularly wireless radio frequency coils, may have color / sensor-coded regions to support guidance for achieving relative overlap within a predetermined critical range. Additionally, audio devices may be individually activated to support optical guidance.

[0026] When a 3D video sensor is used for external 3D sensor-based guidance to achieve relative overlap within a predetermined critical range, the coil can include separate passive or active markers (e.g., regions) to provide contrast for detection with the 3D video sensor. To enable the active markers to operate with extremely low power requirements, the active markers may be modulated and detected by correlation to a reference signal.

[0027] According to one embodiment, at least one coil may include a sensing flexible region. The flexible region may be stretchable. Stretching the flexible region of the coil allows adjustment of the relative overlap between this coil and adjacently positioned coils, particularly with sensing integrated into the flexible region. The flexible region may have markers configured to change distance in response to stretching. Sensing technology integrated into the stretchable region may provide a measurement signal for detecting the relative overlap.

[0028] Alternatively, the flexible region may be configured as a flexible latch or strap including flexible coil conductors or coil electronics to achieve guided adjustment of the relative overlap. When the relative overlap is detected to be within a predetermined critical range, the relative overlap may be secured using a mechanical latch such as Velcro®, a recess, or a securement clamp. The flexible region may include a marker that is sensed by the coil element detection unit. In such cases, the stretchable region may include a coil conductor or coil electronics.

[0029] According to one embodiment, the magnetic resonance imaging device may further include at least one coil holder that holds the at least one coil in place.

[0030] The coil holder may be configured to be attached to clothing or may be a harness. The coils may be secured to the coil holder, preferably with fixtures and markers for individual coil position detection. The coil holder and / or the coils may include sensing technology for detecting relative overlap within a predetermined critical range depending on the patient's individual size. The coil holder may further be configured to hold at least one coil in place during the imaging process to prevent coil displacement, particularly displacement that would move the relative overlap outside the predetermined critical range. The coil holder is applicable to wireless and non-wireless coils and may be combinable with all of the above positioning guidance technologies.

[0031] According to one embodiment, the coil includes an outer cover and an inner cover, the inner cover sliding laterally in two dimensions within the outer cover.

[0032] The coil may be a surface coil that can be manually applied to a patient in a roughly accurate position and then secured, for example, by the patient. The inner core contains the coil elements and may be moved relative to the outer cover, for example, by an integrated software-controlled actuator. The inner core may be movable in two lateral planar dimensions of the surface coil to ensure that the relative overlap falls within a predetermined critical range. Such coils are particularly useful when placed under the patient's body or when the coil is integrated into a moving table.

[0033] According to one embodiment, at least one coil may further include at least one actuator that moves the inner core at least between a first position having no relative overlap and a second position having relative overlap.

[0034] According to one embodiment, at least one actuator is coupled to a control unit that can control the actuator to move the inner core. The actuator can be electrically, pneumatically, or similarly driven. The actuator itself can have a monitoring device, such as a sensor for measuring displacement, and / or can be monitored and / or controlled by another monitoring component of the system.

[0035] According to a second aspect, there is provided a method for generating an image by magnetic resonance imaging. The method includes the steps of: positioning at least two coil elements of at least one coil so that they have a relative overlap with each other on a movable table (preferably on the body of a patient lying on the movable table); detecting the relative overlap of the coil elements; determining whether the detected relative overlap is within a predetermined critical range; repeating the above steps if the detected relative overlap is outside the predetermined critical range; and initiating an image generation process if the detected relative overlap is within the predetermined critical range and the movable table is in a final position for generating an image. The method may be at least partially implemented on a computer, and may be implemented in software and / or hardware.

[0036] The method may enable autonomous detection and guidance of optimal relative overlap of at least two coil elements. Thus, the method may enable patient involvement, for example, through autonomous preparation by the patient themselves, without requiring the physical presence of experienced staff. The method may guide the patient through coil placement so that the relative overlap is within a predetermined critical range. Thus, the method may enable an automated and autonomous magnetic resonance image acquisition process that ensures good image quality.

[0037] According to one embodiment, the method may include monitoring the relative overlap of the coil elements during the image generation process, and repositioning the coil elements during the image generation process if the monitored relative overlap is detected to be outside a predetermined critical range.

[0038] By monitoring the relative overlap of the coil elements during the imaging process, changes in the relative overlap can be detected, and therefore, such changes can be reacted to in a timely manner. Repositioning the coil elements during the imaging process may only be applicable when using coils configured to be automatically positioned by a positioning unit, since the patient may not be allowed to move during the imaging process.

[0039] If not, the effect of the displaced relative overlap on image quality can be estimated, and if necessary, the image generation process can be stopped before completion and restarted from the beginning after manually repositioning the coil elements.

[0040] According to one embodiment, detecting the relative overlap of the coil elements may include determining a noise correlation matrix.

[0041] The noise correlation matrix is ​​a measure of the signal-to-noise ratio. It can be obtained by measuring the electrical signals of individual coil elements. Alternatively, it can be estimated by an AI algorithm in the control unit, by external 3D sensing, or by internal coil sensing.

[0042] The noise correlation matrix can be determined preferably by using localized and / or distributed transmitters in the moving table, in the coil itself, or in the bore of the MR system. If a wireless coil is used, the noise correlation matrix and / or signal coupling can be determined by individual digital transceivers located in the wireless coil. As described above, different coil elements can be individually activated to detect relative overlap and generate corresponding feedback signals to guide coil placement.

[0043] According to one embodiment, determining whether the detected relative overlap is within a predetermined critical range may include comparing the measured noise correlation matrix with a predetermined noise correlation matrix threshold and determining whether the detected relative overlap is within the predetermined critical range based on the comparison result.

[0044] The predetermined noise correlation matrix threshold may vary depending on the region being imaged. The predetermined noise correlation matrix may be stored in the control unit or may be adjusted by the control unit through a machine learning process.

[0045] According to one embodiment, the step of positioning the at least two coil elements may further include the steps of detecting markers provided on the coil or the coil holder, and providing visual and / or audible guidance to manually position the coil elements at positions corresponding to a relative overlap within a predetermined critical range based on the positions of the detected markers.

[0046] A visual and / or audio guidance process may support manual placement of the coil elements, thereby accelerating the placement process.

[0047] According to one embodiment, the step of positioning at least two coil elements of the at least one coil may further include automatically positioning the coil based on at least one software control mechanism incorporated in the at least one coil.

[0048] Automatic coil placement by a software-controlled mechanism can include a surface coil having an outer cover and an inner core, the inner core being movable within the outer cover as outlined above. Another software-controlled mechanism for automatically placing a coil can include a coil with a crawling mechanism that allows the coil to crawl over the patient, guided by, for example, a positioning unit. Once the correct position is achieved, the coil can be fixed in place, for example, by the patient.

[0049] The crawling mechanism can be implemented based on inertia, for example, by first rapidly moving a relatively large mass inside the coil sideways with an actuator, followed by a slow return. During the rapid movement, inertia can move the coil because the friction between the coil and the patient can be overcome. During the slower return movement, friction cannot be overcome, so friction can hold the coil in place. In other words, the rapid, but slow-amplitude, repeated rapid movement and slow return of the mass can effectively cause the coil to crawl along the patient's body.

[0050] According to one embodiment, the method may further include the step of moving the movable table to a final position, which may be performed after determining that the detected relative overlap is within a predetermined critical range or while performing steps necessary to bring the relative overlap within the predetermined critical range. In particular, if a wireless coil is used, moving the table to the final position may be performed during placement of the coil to bring the relative overlap within the predetermined critical range.

[0051] According to a third aspect, there is provided a program element stored on a control unit of a system according to the first aspect, the program element causing the system to perform a method according to the second aspect.

[0052] It should be noted that the above embodiments can be combined with each other regardless of the aspect to which they belong. Thus, a method can be combined with structural features of a system of another aspect, and similarly, a system can be combined with features described above with respect to a method. Advantageously, benefits provided by any of the above aspects and examples apply equally to all of the other aspects and examples, and vice versa.

[0053] These and other aspects of the invention will be elucidated and elucidated with reference to the embodiment(s) described hereinafter. [Brief explanation of the drawings]

[0054] Exemplary embodiments of the present disclosure are described with reference to the following drawings. [Figure 1] FIG. 1 shows a schematic top view of an exemplary embodiment of a system for magnetic resonance imaging. [Figure 2] FIG. 2 shows a schematic diagram of an exemplary arrangement of several coils to illustrate exemplary limits of a given critical range. [Figure 3] FIG. 3 shows a schematic cross-sectional view of an exemplary arrangement of two coils with a relative overlap within a predetermined critical range (FIG. 3a), and a schematic view of an exemplary arrangement of two coils with any relative overlap (FIG. 3b). [Figure 4] FIG. 4 shows a schematic cross-sectional view of an exemplary embodiment of a coil wrapped around a knee. [Figure 5] FIG. 5 shows several schematic and exemplary arrangements of coils to achieve relative overlap. [Figure 6] FIG. 6 shows a schematic diagram illustrating an exemplary embodiment of a surface coil. [Figure 7] FIG. 7 shows a schematic flow diagram of an exemplary method for generating images by magnetic resonance imaging.

[0055] The drawings are merely schematic representations and are intended only to illustrate embodiments of the invention, and identical or similar elements are generally provided with the same reference numerals. DETAILED DESCRIPTION OF THE INVENTION

[0056] 1 shows a schematic representation of an exemplary embodiment of a system 1 for magnetic resonance imaging. The system 1 comprises a magnetic resonance imaging device 2 and a control unit 3, the control unit 3 being configured to control the magnetic resonance imaging device 2.

[0057] The magnetic resonance imaging device 2 includes a magnetic resonance bore 4, a movable table 5 configured to transport a patient 6 into and out of the magnetic resonance bore 4, and several coils 7. Exemplarily and schematically shown in FIG. 1 are a head coil 8, two shoulder coils 9, a neck coil 10, a first anterior coil 11, a second anterior coil 12, and two leg coils 13. Several coils 7 may be grouped, as exemplarily shown by an upper body section 14 including the head coil 8, the two shoulder coils 9, and the neck coil 10. The combination of coils 7 may be selected depending on the region to be imaged and / or individually selected anatomical structures.

[0058] Each coil 7 includes several coil elements 15 fixedly disposed relative to one another and integrated into a coil body 16 (see, for example, FIG. 2 ). As shown in FIG. 1 , the arrangement of the coils 7 exhibits overlapping regions 17 where adjacently disposed coils 7 overlap each other. Within the overlapping regions 17, the coil elements 15 of adjacently disposed coils 7 are disposed to overlap each other. Such relative overlap R (see, for example, FIG. 2 ) of adjacently disposed coil elements 15 can cause noise due to inductively coupled signals of the adjacently disposed coil elements 15. This noise directly affects the quality of the reconstructed image of the magnetic resonance imaging device 2. There is a critical range within which the relative overlap R provides uniform B1 sensitivity, preventing a degradation of the signal-to-noise ratio and resulting in good image quality.

[0059] However, if the relative overlap R is too large or too short, i.e., if the relative overlap is outside the critical range, the adjacently positioned coil elements 15 will not be optimally inductively decoupled, resulting in a loss of signal-to-noise ratio and, depending on the image sequence and image reconstruction algorithm, image artifacts.

[0060] Additionally, movement of the patient 6 and / or coil 7 during the image generation process can adversely affect image reconstruction, which is difficult to prevent. This, combined with relative overlap outside of the critical range, can further complicate image reconstruction and potentially degrade image quality.

[0061] The control unit 3 includes a coil element detection unit 31, an overlap detection unit 32, a determination unit 33, and a position adjustment unit .

[0062] The coil element detection unit 31 is configured to detect adjacently arranged overlapping coil elements 15. The overlap detection unit 32 is configured to detect a relative overlap R of the adjacently arranged overlapping coil elements 15. Both units 31, 32 may be provided separately or integrated.

[0063] The coil elements 15 may be detected by markers (not shown) provided on the coil 7. The markers may be sensed by the coil element detection unit 31 and / or the overlap detection unit 32. The coil element detection unit 31 and the overlap detection unit 32 may comprise 2D sensing technology that senses optical, capacitive, or inductive markers, and / or external 3D sensing technology that detects passive or active markers that provide contrast regions detectable by 3D sensing technology (e.g., radar, lidar, or infrared sensors).

[0064] The determining unit 33 is configured to determine whether the relative overlap R detected by the overlap detection unit 32 is within a critical range, for example, by obtaining an actual noise correlation matrix, comparing the actual noise correlation matrix with a predetermined noise correlation matrix threshold, and determining whether the detected relative overlap R is within the critical range based on the comparison result. Additionally or alternatively, the determining unit 33 may determine whether the detected relative overlap R is within the critical range based on the result of the overlap detection unit 32.

[0065] The position adjustment unit 34 is configured to adjust the relative positions of adjacently disposed overlapping coil elements 15 if the detected relative overlap R is outside a critical range. The position adjustment unit 34 may include an audio guidance device and / or a video guidance device (not shown) to support manual adjustment of the coil position, e.g., performed by the patient 6. The audio guidance device can provide audio guidance, e.g., by audio output of position adjustment instructions, and / or the video guidance device can provide optical guidance, e.g., by displaying the required displacement of the coil 7 by indicating the actual position of the coil 7 and the desired position of the coil 7.

[0066] Additionally or alternatively, the positioning unit 34 may comprise an automatic positioning device configured to automatically adjust the position of the coil 7 without human intervention. In this case, the coil 7 may have a software-controlled actuator controlled by the positioning unit 34.

[0067] Additionally or alternatively, the positioning unit 34 may be configured to automatically select and detune individual coil elements 15, in particular individual coil elements 15 of coil 7, which is a wireless radio frequency coil, to bring the relative overlap R within a predetermined critical range.

[0068] 2-6 show some exemplary embodiments of arranging the coils 7 so that the relative overlap falls within a critical range.

[0069] In FIG. 2, three coils 7, each formed as a thin, flat, blanket-like pad, are arranged so that the coil elements 15 located within the outer edge regions of the coils 7 overlap one another. The thin, flat, blanket-like coils 7 can be formed by arranging the coil elements 15 in an array (not shown), which are fixedly positioned adjacent to one another to form the coil 7. Each coil element 15 shown in FIG. 2 corresponds to one coil element 15 in one coil element array. The relative overlap R1 between a first pair of overlapping coils 7 represents a lower limit of a critical range, and the relative overlap R2 between a second pair of overlapping coils 7 represents an upper limit of the critical range, defining the range within which the relative overlap R does not adversely affect image reconstruction.

[0070] Whether the relative overlap R is within a critical range can be determined by determining the noise correlation matrix. Individual digital transceivers (not shown) located within the coil 7 can measure the noise correlation matrix, and thereby the signal coupling of adjacently located overlapping coil elements 15.

[0071] FIG. 3 shows a schematic cross-sectional view of an exemplary arrangement of two coils 7 arranged to have a relative overlap R. Each coil 7 includes four arrays of fixedly positioned coil elements 15 embedded in a coil body 16. The coils 7 are formed as wireless radio frequency coils. In FIG. 3a, the relative overlap R is within a critical range, while in FIG. 3b, the relative overlap R is too large. The coil elements 15 of the wireless radio frequency coils are configured to be individually adjustable, so that in FIG. 3b, an effective relative overlap R' can be achieved by detuning or deactivating the outer coil element 18 of the upper coil 7 or the outer coil element 18 of the lower coil 7.

[0072] FIG. 4 shows a schematic cross-sectional view of an exemplary embodiment of a coil 7 wrapped around a knee 19 of a patient 6 (see FIG. 1). The coil 7 corresponds to a wireless radio frequency coil including an array of twelve fixedly positioned coil elements 15 incorporated into a coil body 16. In this illustrated embodiment, the coil elements 15 of only one coil 7 are positioned adjacent to each other so as to overlap one another. As with FIG. 3B, depending on the size of the relative overlap R resulting from wrapping the coil around the knee 19, either none of the coil elements 15 can be stopped, or one or more of the coil elements 15 can be stopped to bring the relative overlap R within a critical range.

[0073] FIG. 5 outlines several schematic and exemplary arrangements of the coil 7 for achieving relative overlap R using different mechanical mechanisms, particularly applicable to autonomous positioning of the coil 7 by the control unit 3 (see FIG. 1 ) and autonomous imaging, as will be explained in more detail with reference to FIG. 7 .

[0074] FIG. 5a shows a schematic side view of two adjacently arranged coils 7, and FIG. 5b shows the corresponding top view. According to this exemplary embodiment, the relative overlap R between the two adjacently arranged coils 7 is achieved by providing a flexible and / or stretchable latch 20. By stretching the latch 20 of one coil 7 over the adjacently arranged coil 7, the relative overlap R can be generated and aligned to be within a critical range. For this purpose, the latch 20 includes a marker (not shown) that changes distance depending on stretching. Thus, the marker, functioning as sensor technology 21 (see FIG. 5c), can provide a measurement signal that can be detected by the coil element detection unit 31, the overlap detection unit 32, and / or the determination unit 33. Based on the detected signal and the determined relative overlap R, the position adjustment unit 34 adjusts the position of the latch 20 until the relative overlap R is within the critical range.

[0075] FIG. 5c shows a cross-sectional view of two adjacently positioned overlapping coils 7, each including an embedded sensing technique 21 for aligning the relative overlap R to fall within a critical range.

[0076] Figure 5d substantially combines features of the exemplary embodiment shown in Figure 4 and Figures 5a and 5b. The coil 7 wrappable around the patient's body 6 may further be stretchable to bring the associated overlap R within a critical range.

[0077] Figure 5e shows an exemplary embodiment showing the combination of a volume coil 22 with a flat, thin, blanket-like shaped coil 7. The flat coil 7 may include stretchable regions 23 (see Figure 5f). Both coils 7, 22 include built-in sensing technology 21 for aligning them so that their relative overlap R is within a critical range.

[0078] 5f shows a schematic diagram of an exemplary embodiment of a flat-shaped coil 7 including a stretchable region 23 on the surface of the coil 7. The stretchable region 23 includes markers (not shown) configured to be detectable by 3D sensing techniques, for example provided by the coil element detection unit 31 and / or the overlap detection unit 32.

[0079] FIG. 6 shows a schematic diagram illustrating an exemplary embodiment of a surface coil 24. The surface coil 24 includes an outer cover 25, an inner core 26, and an actuator 27. The inner core 26 is disposed inside the outer cover 25 and corresponds to the coil element 15 that is movable relative to the outer cover 25. The inner core 26 is moved by the actuator 27, which may be controlled, for example, by the position adjustment unit 34 of the control unit 3. The actuator 27 is controlled so that the inner cores 26 of adjacently arranged overlapping surface coils 24 that are arranged so as not to have a relative overlap (see FIG. 6a) are moved so that the relative overlap R between the inner cores 26 falls within a critical range (see FIG. 6b).

[0080] 7 shows a schematic flow diagram of an exemplary method 100 for generating an image by magnetic resonance imaging. The method 100 for generating an image by magnetic resonance imaging preferably, but not necessarily, includes the following steps in the following order: In step S1, at least two coil elements 15 of at least one coil 7 are positioned with respect to one another on the movable table 5 to have a relative overlap R, e.g., by detecting markers provided on the coil 7 or a coil holder (not shown), e.g., via the coil element detection unit 31 and / or the positioning unit 34. The positioning may include visual and / or audible guidance to manually position the coil elements 15 at positions corresponding to the relative overlap R within a predetermined critical range based on the positions of the detected markers. Additionally or alternatively, the positioning may include automatic positioning of at least one coil 7 based on at least one software control mechanism incorporated in the coil 7.

[0081] In step S2, the relative overlap R of the coil elements 15 is detected, preferably by the overlap detection unit 21, for example by measuring a noise correlation matrix. In step S3, it is determined, preferably by the determination unit 33 of the control unit 3, whether the detected relative overlap R is within a predetermined critical range, for example by comparing the measured noise correlation matrix with a predetermined noise correlation matrix threshold and determining, based on the comparison result, whether the detected relative overlap R is within a predetermined critical range. If the detected relative overlap R is outside the predetermined critical range, steps S1 to S3 are repeated until the detected relative overlap R is within the predetermined critical range (step S4), after which the image generation process is started when the movable table 5 is in a final position for generating an image (step S5).

[0082] Method 100 may further include the following steps not shown in FIG. 7 : monitoring the relative overlap R of the coil elements 15 during the image generation process, and automatically repositioning the coil elements 15 during the image generation process when the monitored relative overlap R is detected to be outside a predetermined critical range. [Explanation of symbols]

[0083] 1 System 2. Magnetic resonance imaging data 3. Control Unit 4. Magnetic resonance data 5 Movable table 6 patients 7 coils 8 Head Coil 9 Shoulder Coil 10 Cervical Coil 11 First anterior coil 12 Second anterior coil 13 Leg Coil 14 Upper Body Section 15 coil elements 16 Coil body 17 Overlapping Areas 18 outer coil elements 19 Knee 20 Latch 21 Sensing Technology 22 volume coil 23 Stretch area 24 surface coil 25 Outer cover 26 Inner Core 27 Actuator 31 Coil element detection unit 32 Overlap detection unit 33 Judgment Unit 34 Position adjustment unit 100 ways R Relative overlap R' effective relative overlap R1 lower limit R2 upper limit

Claims

1. A system for magnetic resonance imaging, comprising a magnetic resonance imaging device and a control unit for controlling the magnetic resonance imaging device, The magnetic resonance imaging device a magnetic resonance bore; a movable table movable into and out of the magnetic resonance bore; at least two coil elements of at least one coil, the two coil elements being arranged adjacent to each other on the movable table with a relative overlap, the at least one coil including an outer cover and an inner core, the inner core including the at least two coil elements, the inner core sliding laterally in two dimensions within the outer cover; The control unit a coil element detection unit for detecting the at least two coil elements; an overlap detection unit for detecting the relative overlap of the at least two coil elements; a determining unit for determining whether the detected relative overlap is within a predetermined critical range; a position adjustment unit that adjusts the relative positions of the coil elements if the detected relative overlap is outside the critical range.

2. The system of claim 1 , wherein the at least two coil elements are coil elements from different coils.

3. The system of claim 2 , wherein the at least one coil is in the form of a flat, thin, blanket-like pad.

4. 4. The system of claim 1, wherein the coil element detection unit includes at least one sensor for detecting markers of the coil, the sensor being selected from a 2D sensor group of optical video sensors, capacitive sensors, and inductive sensors, or the sensor being selected from a 3D video sensor group of radar sensors, lidar sensors, and infrared sensors.

5. The system of claim 1 , wherein the at least one coil includes a sensing flexible region.

6. The system of claim 1 , wherein the magnetic resonance imaging device further comprises at least one coil holder that holds the at least one coil in place.

7. 7. The system of claim 1, wherein the at least one coil further comprises at least one actuator that moves the inner core at least between a first position having no relative overlap and a second position having the relative overlap.

8. The system of claim 7 , wherein the at least one actuator is coupled to the control unit, the control unit controlling the actuator to move the inner core.

9. 1. A method of producing an image by magnetic resonance imaging, said method comprising: (a) arranging at least two coil elements of at least one coil to have a relative overlap with each other on a movable table, the at least one coil including an outer cover and an inner core, the inner core including the at least two coil elements, the inner core sliding laterally in two dimensions within the outer cover; (b) detecting the relative overlap of the coil elements; (c) determining whether the detected relative overlap is within a predetermined critical range; (d) repeating steps (a)-(c) if the detected relative overlap is outside the predetermined critical range; (e) initiating an image generation process when the detected relative overlap is within the predetermined critical range and the movable table is in a final position for generating an image.

10. (f) monitoring the relative overlap of the coil elements during the imaging process; 10. The method of claim 9, further comprising: (g) repositioning the coil elements during the imaging process if the monitored relative overlap is detected to be outside the predetermined critical range.

11. 11. The method of claim 9 or 10, wherein detecting the relative overlap of the coil elements comprises determining a noise correlation matrix.

12. 12. The method of claim 9 or 11, wherein determining whether the detected relative overlap is within a predetermined critical range comprises comparing the measured noise correlation matrix with a predetermined noise correlation matrix threshold and determining whether the detected relative overlap is within the predetermined critical range based on a comparison result.

13. 13. The method according to claim 9, wherein the step of positioning the at least two coil elements further comprises the steps of: detecting markers provided on the coil or a coil holder; and providing visual and / or audible guidance to manually position the coil elements at positions corresponding to a relative overlap within the predetermined critical range based on positions of the detected markers.

14. 13. The method of claim 9, wherein the step of positioning at least two coil elements of at least one coil further comprises automatically positioning the coil based on at least one software control mechanism embedded in the at least one coil.

15. A program stored in a control unit of a system according to any one of claims 1 to 8, said program causing said system to carry out a method according to any one of claims 9 to 14.

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