Measurement apparatus and method for measuring activity of patient and magnetic resonance apparatus

Abstract

The invention relates to a measuring device (3) for measuring the movement of a patient (1) positioned in a prone position on a patient bed (2), in particular in a magnetic resonance apparatus (13), comprising:-the patient bed (2), and-at least one flexible fastening strap (6) for locally fastening the patient (1) to the patient bed (2), the fastening strap (6) having at least one first fastening means (9) for fastening the patient (1) to the patient bed (2), the invention relates to a fixing device (1) for a patient lying in bed (2), comprising a fixing band (6), which has a first fastening element (14) that interacts with a second fastening element (10) of the patient lying in bed (2) in order to fasten the fixing band (6), characterized by at least one stress sensor (16), which is designed as a component of and / or movably coupled to the fixing band (6), and a control device (27), which controls the at least one stress sensor (16). For determining activity information describing an activity of the patient (1) from sensor data of the strain sensor (16).

Description

Technical Field

[0001] The invention relates to a measuring device for measuring the movement of a patient positioned in a supine position on a patient bed, in particular in a magnetic resonance system, the measuring device comprising:

[0002] - The patient is bedridden, and

[0003] - At least one flexible fixing belt for partially fixing the patient on the patient bed, wherein the fixing belt has at least one first fastening element which cooperates with a second fastening element of the patient bed in order to fasten the fixing belt.

[0004] The invention also relates to a magnetic resonance system and a method for operating a measuring system. Background Art

[0005] For examinations and surgeries, for example, using medical imaging devices, the patient is usually positioned on a patient couch. This applies in particular to examinations and surgeries that are sensitive to the patient's movements. This applies, for example, to imaging methods that use recording modes that require a significant amount of time. Computed tomography, positron emission tomography (PET) and magnetic resonance imaging (MRI) are typical imaging modes in which movements can occur during the recording time, resulting in limited image quality and, in particular, the appearance of artifacts.

[0006] Undetected or uncompensated, in particular uncompensated, patient movements can lead to, for example, strong image artifacts, which can render the entire image data set unusable. In addition, poor-quality image data sets can hamper clinical findings and diagnosis as well as monitoring of surgical procedures. In particular, magnetic resonance imaging can be affected by patient movement due to the long duration of magnetic resonance acquisition sequences (MRI sequences).

[0007] Here, patient activity includes involuntary activity, such as twitching or muscle spasms, and includes periodic activity, such as breathing and heart beats, and also includes conscious activity of the patient. Therefore, a reliable method for detecting and quantifying patient activity would be useful to reacquire at least a portion of image data that is unusable due to the activity, and / or to trigger image data acquisition during time intervals with little or no movement, and / or to implement different activity correction and / or activity compensation algorithms.

[0008] Several solutions have been proposed in the prior art to detect patient activity. Commonly used examples involve the use of mechanical sensors, such as breathing belts, etc. However, mechanical sensors, like for example EKG devices for electrically measuring the heartbeat, can lead to discomfort for the patient and / or an overload of the workflow during image data acquisition. In particular, additional time and expertise are required for the personnel to place the additional sensor device on the patient and to operate it.

[0009] Furthermore, in a common field of application, it is proposed to monitor the patient remotely and continuously using sensor technology, for example by recording an image of the patient by at least one video camera. In the evaluation, for example, landmarks on or near the patient can be tracked in order to draw conclusions about the patient's movements. However, the problem that arises here is that the direct line of sight between the sensor and the patient is obstructed, for example by a blanket covering the patient or by auxiliary devices positioned around the patient.

[0010] In particular in the field of magnetic resonance imaging, further methods are known in order to detect and, ideally, also to quantify the movements of a patient.

[0011] The first example for this is the so-called pilot sound method. For example, it is provided that a special pilot sound transmitter is integrated in the patient's bed, especially under or in the support surface for the patient, and the pilot sound transmitter emits a special pilot sound signal close to the Larmor frequency. The pilot sound signal is received and evaluated by a receiving coil, for example, a local coil device arranged on the patient. However, this type of solution is considered to be sensitive to external interference, such as external interference caused by the cold head of the cooling device, the gradient coil cable, etc. during magnetic resonance imaging. Significant intervention must be taken in the control software of the magnetic resonance imaging to allow the operation of the pilot sound receiving chain. This is also particularly applicable outside the reading time range. In addition, the aforementioned scheme is also closely related to the operator's skilled positioning of the receiving coil. Another highly relevant problem is that the pilot sound method cannot detect patient activities that occur away from the active receiving coil, but especially when the main magnetic field strength is high, it will cause field fluctuations of the main magnetic field in the field of view. For example, when performing a head examination in a high-intensity field such as 3 to 7 Tesla, the influence of respiratory movement that cannot be measured due to the lack of a receiving coil may occur. In addition, the frequency of the pilot sound signal must be reselected for each field strength. Generally, this method is not compatible with multi-nuclear MRI.

[0012] In other methods, magnetic resonance imaging provides for magnetic field sensors, in particular Hall sensors, to be integrated in the local coil arrangement. This type of patient movement is based on the ability of the magnetic field sensor to detect its own movement (triggered by the movement of the local coil arrangement) in a magnetic field with a uniform field intensity (homogeneous volume). However, the problem here is that if the magnetic field sensor is moved in parallel, so that its angle relative to the main magnetic field direction remains constant, then no field changes occur and thus no significant patient movement can be detected at all.

[0013] Furthermore, both the method using magnetic field sensors and the pilot sound method have in common that they presuppose the use of a new type of local coil device that should be specially distributed on an existing magnetic resonance device. Such a local coil device includes a dedicated built-in electronic unit. The user cannot use the local coil device with a new magnetic resonance device or cannot use the local coil device of a manufacturer that also does not provide a magnetic resonance device. This increases the cost and hinders the application of this technology. Summary of the invention

[0014] The object of the present invention is therefore to provide a relatively improved, accurate possibility that can be implemented more simply, in particular in magnetic resonance imaging, for detecting patient movements of a patient positioned on a patient bed.

[0015] This object is achieved according to the invention by a measuring device, a magnetic resonance device and a method according to the independent claims. Advantageous embodiments are given in the dependent claims.

[0016] According to the invention, a measuring device of the aforementioned type also has:

[0017] at least one stress sensor which is designed as a component of the fixing strap and / or is movably coupled to the fixing strap, at least in the fastened state, via a fastening element, and

[0018] - A control device for determining movement information describing the movement of the patient from the sensor data of the strain sensor.

[0019] Therefore, the concept on which the present invention is based is that auxiliary devices that may be used, for example, during examination and / or surgery, and in particular should be arranged near and / or on the patient, and / or the patient himself are directly fixed at least partially to the patient bed by at least one fixing belt. The patient's activities thus act directly or at least indirectly, for example indirectly through auxiliary devices, on the fixing belt, so that a tension or a change in tension is formed there, which describes the patient's activities. Therefore, it is provided that this type of tension is detected using a suitably positioned stress sensor, for example at least one stress sensor for each fixing belt. The measurement signal thus formed, which describes the force acting on the fixing belt, that is, the sensor data describes the patient's activity that caused the measured force. Therefore, the sensor data can be evaluated in the control device of the measuring device to form activity information describing the patient's activities.

[0020] As will be described in more detail below, the activity information can be set differently depending on the field of application and / or focus on different activity types. This means that in a simple design, the activity information can, for example, simply indicate whether there is a patient activity that exceeds a certain threshold value for the activity intensity. This can also be relative to different activity types. However, it is feasible and preferred that the activity information quantifies the patient activity detected for at least one activity type. This means that, for example, the activity information can describe and, if necessary, analyze it depending on the activity type: what is the curve of the patient's activity over time. In general, the control device is designed to determine activity information to describe the location and / or intensity and / or type of the patient's activity.

[0021] The activity information can be used in different ways and methods within the scope of the examination and / or operation of the patient, for example for triggering a detection process and / or an operation process, for identifying detection data disturbed by activity and / or for correcting and / or compensating for the activity of the detection data. The invention is implemented in particular in the field of medical imaging, wherein the control device can correspond to the control device of the corresponding imaging device. The application in magnetic resonance imaging affected by the patient's activity is particularly advantageous. In this regard, it can also be provided in other imaging modes that the activity information is used by the control device in order to retake at least a part of the image data that cannot be used due to activity, and / or to trigger the recording of image data for time intervals with little or no activity, and / or to execute different algorithms for activity correction and / or activity compensation, which use the activity information as input data.

[0022] Within the scope of the present invention, activity types may include in particular periodic patient activities, such as heartbeats and / or breathing, which due to their periodicity and known frequency range can be easily determined in the sensor data by corresponding evaluation functions. However, intermittent activities, such as unconscious and / or conscious activities of the patient, may also be detected as activity types.

[0023] It should be noted here that the evaluation function of the control device, which evaluates the sensor data around the activity information, can obviously also use other information in addition to the sensor data as input data. In particular, background information can be taken into account, which describes in particular the type of mechanical interaction with the stress sensor triggered by the activity. For this purpose, the control device can in particular take into account background information present in a memory of the control device when determining the activity information, which background information is about the properties of the fastening belt and / or the properties of the auxiliary device and / or the type of fastening.

[0024] As mentioned above, the measuring device can be particularly advantageously used as part of a magnetic resonance device or in a magnetic resonance device for magnetic resonance imaging. In magnetic resonance imaging, a local coil device with at least one transmitting coil and / or receiving coil is usually used as an auxiliary device to, for example, detect weakened magnetic resonance signals, which are induced in different tissues in the human body and emitted therefrom. Currently known local coil devices include a plurality of receiving coils, which are spatially dispersed in a two-dimensional or three-dimensional matrix or array-like layout. The local coil device can, for example, be flexible enough so that the local coil device bends due to the patient's anatomical structure. In order to reduce high-frequency noise in the received magnetic resonance signal, the receiving coil is as close to the patient's body as possible. In order to avoid image artifacts and due to the sensitivity characteristics of the receiving coil that change with the relative position to the patient's anatomical structure, the local coil device must be kept in an initial position without movement or slippage, in which the sensitivity characteristics have been calibrated.

[0025] In order to achieve this, it has been provided in the prior art that the local coil device is provided with at least one fixing strap, in particular a plurality of fixing straps, so that the fixing straps can be bent and fastened to the patient's body and for limiting the local coil device at the same time, so that the local coil device is kept in the same position during the entire examination process. The at least one fixing strap can be fastened in the support of the local coil device by a fastening device, such as a corresponding receptacle, and preferably the length of the fixing strap can be freely adjusted and fastened to the local coil device. At least one fixing strap has a first fastening element, such as a plug element, at the ends opposite to each other, which can be fastened to a second fastening element, such as a socket element, on the patient's bedside. By the adjustability of the free length of the at least one fixing strap for fastening, the user can adjust the mechanical stress in the fixing strap, so that on the one hand, discomfort to the patient is avoided, but on the other hand, a change in the position of the local coil device or other auxiliary devices is avoided.

[0026] In relation to other basically known fixing straps of this type, the invention makes use of the practical observation that any type of patient movement is automatically converted into a change in the tensile force generated by the fixing straps. For example, as already described in detail above, if the local coil arrangement is fastened to a patient couch at four fastening points in magnetic resonance imaging using four fixing straps (e.g. two points on the left side of the patient by means of one insertion channel and two points on the right side of the patient by means of another insertion channel), the fixing straps are the subject of the changing tensile force, which is transmitted, for example, in the case of a flexible but at least substantially inextensible fixing strap to a second fastening element of the patient couch, where it is converted into a changing tensile force, for example, acting on the second fastening element, in particular on the insertion channel.

[0027] In other words, and generally for any type of unconscious or conscious activity of the patient, such as breathing, heartbeat and / or muscle spasms, low-amplitude mechanical tremors are caused along the fixing belt and in the inextensible, especially inelastic fixing belt up to the second fastening element on the patient's bedside. This is particularly evident in the case of significant patient activity, such as coughing, pain or panic.

[0028] In this case, provision can be made, in particular in connection with the examination, to use a plurality of fixing straps along the length of the patient, for example for fastening a plurality of auxiliary devices, for example local coil arrangements. In whole-body magnetic resonance imaging, for example, the local coil arrangements and the corresponding fixing straps are distributed at a plurality of locations along the human body, so that patient movements at different locations can be detected by means of strain sensors along at least one side, preferably two sides. In contrast to the methods known from the prior art, which are based, for example, on receiving signals by means of receiving coils, patient movements outside the current field of view can also be detected, in particular away from the active receiving coils and even away from the current homogeneous volume relative to the patient bed and the patient.

[0029] Generally, it is provided within the scope of the present invention that a stress sensor is used in order to measure the patient's movement detected by at least one fixation belt, preferably a plurality of fixation belts. A stress sensor is a sensor that measures a tensile force, such as stress and / or bending, which causes a deformation of a measuring element. Within the scope of the present invention, a stress sensor can in particular comprise a sensor element, which yields to the force to be measured, in particular deforms, directly or indirectly, for example by being placed on the measuring element. Generally, the sensor element itself is made of a soft and ductile, in particular elastic material. In addition, the stress sensor can comprise a control unit in order to derive sensor data from a signal originating from the sensor element and / or a property of the sensor element. For this purpose, a large number of different types of stress sensors have been provided in the prior art, which can also be applied within the scope of the present invention. Known types of stress sensors include, for example, rheological stress sensors, which include an electrical conductor, the resistance of which changes when the sensor element is deformed. In addition, capacitive stress sensors are known, in which the sensor element includes a distributed capacitor, the capacitance of which changes when a deformation occurs. A third type of stress sensor uses a piezoelectric material in a soft, flexible or ductile form as a sensor element, wherein the properties of the piezoelectric material are used for the form conversion between mechanical energy and electrical energy. Finally and preferably for magnetic resonance imaging, some types of stress sensors are also known which use optical fibers in the sensor element, which will be described in more detail below.

[0030] As mentioned above, within the scope of the invention it can be provided that the measuring device also has an auxiliary device, in particular a local coil device, which is arranged on the patient and fixed there, and at least two of the plurality of fixing straps are fastened to the auxiliary device by means of a fastening device via the ends opposite the first fastening element.

[0031] However, in an embodiment of the present invention, a fixing belt that is independent of the auxiliary device and in particular separated from the auxiliary device can also be used. Therefore, it can be provided that at least one of the at least one fixing belt has a first fastener on both sides, and the first fastener is used for the mutually opposite second fasteners of the patient bed. This type of fixing belt can be used to fix the patient directly and locally on the patient bed, but of course it can also be used to keep the auxiliary device in a fixed position on the patient. For this purpose, a flexible fixing belt with two first fasteners can be placed on the auxiliary device and / or on the target anatomical structure, and in particular after adjusting the corresponding length of the fixing belt by the corresponding adjustment device of the fixing belt, it is fastened with the mutually opposite second fasteners of the patient bed in the transverse direction (perpendicular to the longitudinal direction).

[0032] In particular, a flexible fixing belt can be provided which is not part of an auxiliary device, for example, not part of a local coil arrangement, but can be used in combination with any auxiliary device, for example, any local coil arrangement, in order to detect patient movements in a body region arranged mechanically close to the flexible fixing belt. The user can adjust the length of the fixing belt in order to adjust the mechanical tension in the fixing belt so that sufficiently good patient movement detection is possible and the auxiliary device does not move unintentionally. That is to say, for example, within the scope of the invention, a separate fixing belt can be used to fix a flexible local coil arrangement, for example, a knee coil, a shoulder coil, an elbow coil, etc., to a corresponding anatomical part of a patient in order to prevent its movement.

[0033] However, a separate, flexible fixing belt of this type can also be used with a rigid local coil arrangement of the prior art, such as a rigid head coil or a rigid knee coil. In this case, the fixing belt is, for example, arranged directly on the patient, in particular on the brain or the chin or around the leg near the knee, in order to measure the movement of the head or the leg.

[0034] Particularly advantageously, such a fixing belt can also be used to measure the movement of different body parts of a patient, even when auxiliary devices, such as a local coil arrangement, are not fastened to the body part, by merely placing the fixing belt around the body part and fastening it by means of the first fastening means, and by sufficiently tensioning the auxiliary device during use. Such a use scenario is advantageous, for example, when the heartbeat or respiratory movement is to be tracked during head surgery. This is particularly useful within the scope of magnetic resonance imaging, since a possible weakening of the magnetic field in the field of view caused by such movement is avoided and / or corrected.

[0035] For all associated integral structures that can be fastened on both sides of the patient bed, in particular auxiliary means together with the fastening belts that can be fastened on each side and / or on both sides of the patient bed, it is expedient to acquire sensor data by at least one stress sensor in the transverse direction on both sides (i.e. on the left and right side of the patient). Since the invention is based on a fastening belt that is at least somewhat stressed (since no measurement is possible with a sagging / loose belt), in a two-sided measurement, a stress release on one side leads to a measurable tensile force on the other side.

[0036] Within the scope of the invention, two basic embodiments can be distinguished. In a less preferred first embodiment, it can be provided that the sensor element of the stress sensor, in particular a strain gauge, is arranged on an elastic portion of at least one of the at least one fixing strap. In this case, the fixing strap is at least partially extensible / elastic and can exhibit deformations in this elastic portion due to patient movement, which deformations can be measured by the sensor element of the stress sensor. However, if a control unit of the fixing strap is also provided here, the signals or sensor data are transmitted from the fixing strap to the control device via a suitable interface.

[0037] In this case, it can be provided that, if the fixing strap is fastened to the auxiliary component, the sensor element is connected wirelessly or by wire to a control unit of the stress sensor on or in the auxiliary component, in particular in the electronic unit of the auxiliary component. When a local coil device is used as an auxiliary component, it can be provided, for example, that the control unit of the stress sensor is integrated in the electronic unit of the local coil device, which is present all the way. The fastening device can be, in particular, a wired interface for communication between the sensor element and the control unit. In this case, it is particularly suitable to arrange the sensor element adjacent to the fastening device, because this results in a shorter transmission path. This type of design is less preferred, because a special design of the auxiliary component, in particular the local coil device, is required, which limits the universal usability.

[0038] However, in other designs, it is possible that at least one of the fastening elements has an interface for connecting the sensor element to the control unit on the patient's bedside. In this case, only the fixing belt needs to be specially designed. If the fixing belt is arranged independently of the auxiliary device, for example, a fixing belt with the first fastening element on both sides as described above, no special auxiliary device needs to be designed. Moreover, in this design, it is particularly suitable to arrange the sensor element adjacent to the first fastening element in order to keep the transmission path short.

[0039] However, in a particularly preferred second embodiment, it can be provided that the changing tensile force to be measured is transmitted to the measuring site on the patient's bed side via a preferably, in particular flexible, but at least substantially inextensible, in particular inelastic fixing belt. It can be conveniently provided that the fixing belt is designed to be substantially inextensible, in particular inelastic, in order to achieve the force transmission of the force to be measured. However, the second embodiment does not exclude a certain degree of extensibility or elasticity of the fixing belt, as long as at least a part of the (smaller) tensile force to be measured is transmitted to the patient's bed via the first (preferably rigid) fastener and causes an effect there that can be measured by the stress sensor.

[0040] In this case, it is particularly suitable if the fixing belt has an adjustment element for adjusting the belt length of the fixing belt. This type of adjustment element is particularly suitable when the ductility or elasticity cannot lead to a change in length. The fixing belt can thus be adjusted by means of the adjustment element so that it fits the auxiliary device and / or the patient and is thus affected by any movement of the auxiliary device and / or the patient, in particular detecting this movement and thus transmitting a corresponding tensile force via the first fastening element.

[0041] One embodiment in which the strain sensor is preferably provided on the patient bed has the particular advantage that an "upgrade" can be achieved simply by refitting the patient bed (and optionally providing suitable, in particular inelastic fixing straps). Auxiliary components, in particular the local coil arrangement, can still be used as usual. Moreover, the fixing straps are usually designed to have a sufficiently low ductility to allow adequate force transmission. For example, in a magnetic resonance system, it is sufficient to replace the patient bed to use the measuring option according to the invention. All equipment, in particular auxiliary components and (inelastic) fixing straps, can continue to be used.

[0042] It should also be noted here that even if the measurement on the patient's bed side is preferred, it is still conceivable to provide the strain sensor on the auxiliary device, in particular the fastening device side of the local coil device. However, this is less preferred because a special design of the auxiliary device is required.

[0043] Therefore, a particularly preferred embodiment of the invention provides that at least one of the at least one stress sensor is arranged at the first and / or preferably second fastening element. The basic idea of ​​the invention is that due to the inextensibility of the fixing belt, the tensile force is preferably transmitted to the second fastening element, on which the stress sensor is arranged, without complex data transmission from and / or to the fixing belt. In other words, by transmitting the tensile force through the combination of the first and second fastening elements, at least one stress sensor can be installed in the patient bed.

[0044] This avoids possible disadvantages, such as a higher complexity and higher current requirement of the auxiliary components, in particular the electronics of the local coil arrangement, and / or data transfer that is difficult to implement, in particular in the field of magnetic resonance. In addition, compatibility with auxiliary components and / or fixing straps from third-party suppliers can also be provided.

[0045] In a particularly advantageous improvement of the redesign of the second embodiment, it can be provided that the first fastening element has a fastening element, in particular a latching element, which in the fastened state abuts against a measuring element of the second fastening element, wherein the measuring element is configured as a sensor element of a stress sensor, or the sensor element of the stress sensor is arranged on the measuring element. In this case, the first fastening element and the second fastening element are in particular designed to establish a latching connection and / or a clamping connection. Particularly advantageously, the fastening element can first be embedded in the second fastening element against a reset force and latched there, for example in a cavity (accommodation cavity) serving as a receptacle, and abut against the measuring element of the second fastening element in a manner that prevents it from being disengaged, in order to establish a fastened connection. The anti-detachment protection also allows a relative force transmission of tensile forces from the fixing strip via the fastening element to the measuring element, and allows its, in particular its local deformation, which can be measured by the stress sensor.

[0046] It should also be noted here that the measuring element does not require a strong elasticity / deformability, since modern strain sensors (which will be described in more detail below) can already measure relatively small changes in the measuring element and thus in the sensor element reliably and accurately enough.

[0047] In a suitable specific design, it can be provided that the second fastener is constructed as an insertion channel for inserting the first fastener into any position covered by the insertion channel, in particular along the longitudinal direction of the patient bed. This basically known insertion channel has been suggested in the prior art and allows the first fastener to be inserted flexibly and freely selectably in a longitudinal position along the channel length covered by the insertion channel. For example, the patient bed can have at least two insertion channels, at least substantially over its entire length, at least one of which is arranged on the right side of the patient bed and at least one is arranged on the left side of the patient bed. Another pair of shorter insertion channels that are mutually opposed in the transverse direction can be arranged, for example, in the area of ​​the head and / or in the area of ​​the arms and / or in the area of ​​the legs.

[0048] Here, the measuring element can define the boundaries of the insertion slit of the insertion channel and define the boundaries of the cavity widened relative to the insertion slit and constructed to accommodate the fastening element. The fastening element is particularly related to a locking pin, which is locked and embedded in the cavity widened relative to the insertion slit under the measuring element or in the measuring element when the first fastener is introduced into the insertion slit of the insertion channel. Of course, other specific designs can also be considered, for example, in which the widened cavity is constructed as a groove along the measuring element. Usually, the first fastener in this case can also be a plug piece, which can be inserted into the insertion channel so that the fastening element and the measuring element are in contact with each other on at least one surface along the insertion direction. The transmission of the pulling force and the deformation of the measuring element are achieved through this contact, and the deformation is converted into motion data to a certain extent using a stress sensor.

[0049] The measuring element and thus the stress sensor itself can conveniently extend in the longitudinal direction of the insertion channel, in particular over its entire length, in particular due to the freely selectable insertion position. It can therefore be provided that the measuring element and / or the sensor element covers the entire length of at least one of the at least one insertion channel. It is particularly suitable that in an advantageous development the stress sensor is designed for spatially resolved measurement of the influence of the fastening element on the measuring element. In this way, it is possible to determine which effect, in particular which deformation, is caused by which first fastening element and preferably also the exact position of the first fastening element, in particular when a plurality of first fastening elements are inserted over the length of the insertion channel.

[0050] However, it is also conceivable that at least one of the at least one insertion channel has a plurality of measuring elements and / or a plurality of sensor elements for occupying a plurality of different channel sections of the entire length of the insertion channel. The channel section can define the insertion area for each fixing belt. In this design mode, the insertion channel is finally segmented, wherein each channel section that is sensitive to activity therefore has a respective stress sensor. The sensor data of the stress sensors of all channel sections can be transmitted to the control device, and the evaluation of the motion information can be carried out according to the position and channel section of the stress sensor. It is also conceivable in particular that only a part of the insertion channel is segmented, such as two outsides, arranged on the right and left sides, and especially at least substantially covering the insertion section of the entire length of the patient's bed, and other insertion sections, such as in the inner area of ​​the patient's bed, can also only have a unique measuring element or sensor element covering the entire length of the insertion channel. In this way, when the measurement of spatial resolution cannot be realized using the stress sensor, the position information of the relevant sensor data can also be obtained.

[0051] As already mentioned, it is preferred in this case, however, that the stress sensor is designed for spatially resolved measurement of the effect of the fastening element on the measuring element. In this case, the stress sensor can be designed in particular as a fiber sensor with a fiber Bragg grating. A fiber Bragg grating (FBG) is a distributed Bragg reflector in which the refractive index of the fiber core varies periodically. Since the fiber Bragg grating reacts sensitively to stretching or general deformation, the fiber sensor can measure the change of the Bragg wavelength. In order to achieve spatially resolved measurement, a distributed fiber Bragg grating is arranged in the optical fiber, so that when the distance between the fiber Bragg gratings is mechanically disturbed, the local refractive index changes, which can be detected by an optical readout system at the end of the fiber. This design has the particular advantage that even if the optical fiber is very long, for example as long as the entire patient bed or the longest insertion channel, the exact position of the mechanical disturbance acting on the fiber core can be determined by the measured light signal. Other types of fiber sensors may also be suitable.

[0052] In general, various types of sensors can be used as stress sensors in the context of the invention, as has already been explained at the outset.

[0053] For example, at least one stress sensor can be designed as a rheological and / or capacitive stress sensor. In this case, the bending or stretching of the measuring element is determined by strain gauges, which can be applied to two or more sections of the measuring element. For example, a Wheatstone bridge can be formed, which is well known in the prior art. Capacitive strain sensors, which are also known in the prior art, can also be used. A general rule for rheological and / or capacitive sensors is that the rheological and / or capacitive stress sensor can have a strip and / or a flat webbing and / or a rope as sensor element.

[0054] Furthermore, it is conceivable that at least one of the strain sensors comprises at least one piezoelectric material as a sensor element. In particular, such piezoelectric strain sensors (also known in principle) can have distributed piezoelectric sensors, in particular also allowing spatially resolved measurements.

[0055] However, it is particularly advantageous if at least one strain sensor, in particular each strain sensor, has an optical fiber as a sensor element with a measurement signal carrier, in particular a sensor element based on a ductile optical fiber and / or a fiber Bragg grating sensor element. The advantage of optical fibers as measurement signal carriers in magnetic resonance imaging is that they are highly compatible with the electromagnetic high-frequency fields used in magnetic resonance imaging. This makes it possible to avoid interference with the imaging operation.

[0056] The deformation of the sensor element can be converted into an electrical signal by a stretchable optical fiber or the like. Like conventional optical fibers, stretchable optical fibers, especially elastic optical fibers, include a core with a high refractive index (e.g. made of polystyrene-polyisoprene triblock copolymer) and a cladding with a low refractive index (e.g. made of a fluorinated thermoplastic elastomer). For example, a stretchable optical fiber can be repeatedly stretched to three times its length. The axial deformation of the stretchable optical fiber will cause a change in its light-guiding properties, which can be read out by a light source and a photodetector at the end of the optical fiber.

[0057] As mentioned above, the light sensor using the fiber Bragg grating can of course be generally applicable.

[0058] In an advantageous development of the invention, the control device compensates for activities, in particular vibrations, caused by the operation of components of the magnetic resonance system, in particular gradient coils, based on compensation information obtained in the calibration measurement. In particular, in the field of magnetic resonance imaging, interfering vibrations often occur, in particular interfering vibrations from the gradient coils. In order to improve the sensor data in this respect, vibrations caused by gradient activities (i.e. gradient pulses emitted by the gradient coils), in particular deformations of the sensor elements, can be measured in the calibration measurement, i.e. in the absence of a patient, and this compensation information can be used in the presence of a patient to correct the sensor data, in particular the signals from the sensor elements, accordingly. For example, using a known, running magnetic resonance sequence, it is possible to determine from the compensation information which interfering signals or interfering data have occurred and remove these interfering signals or interfering data from the signals of the sensor elements and / or the sensor data, for example by subtraction. In this way, the quality of the sensor data is improved and a more robust evaluation is achieved.

[0059] Furthermore, it can be expedient to provide that the control device is designed to determine the activity information using a trained evaluation function, which uses the sensor data as input data. In other words, artificial intelligence and / or machine learning, in particular deep learning, can be used to quickly and robustly determine the activity information.

[0060] Generally speaking, trained functions map cognitive functions that humans associate with other human brains. Through training based on training data (machine learning), trained functions have the ability to adapt to new environments and can discover and infer patterns.

[0061] Generally speaking, the parameters of the training function can be adjusted by training. In particular, supervised learning, semi-supervised learning, unsupervised learning, reinforcement learning and / or active learning can be used. In addition, representation learning (also called "feature learning") can also be used. In particular, the parameters of the training function can be repeatedly adjusted through multiple training steps.

[0062] For example, the training function may include a neural network, a support vector machine (SVM), a decision tree and / or a Bayesian network, and / or the training function may be based on mean clustering, Q-learning, a genetic algorithm and / or an association rule. In particular, the neural network may be a deep neural network, a convolutional neural network (CNN) or a deep CNN. In addition, the neural network may also be an adversarial network, a deep adversarial network and / or a generative adversarial network (GAN).

[0063] In the context of the invention, it can be provided that the evaluation function is trained, in particular based on a large amount of empirical data, to detect and separate different activity types. For example, special fluctuation shapes of breathing and / or heartbeat can be separated, wherein reinforcement learning is preferably used. In this case, it can be provided that the EKG signal and / or the breathing signal are acquired together with the sensor data as training input data of the training data set and provided as basic facts or otherwise incorporated into the learning process.

[0064] In an improved solution of the present invention, the measuring device further comprises:

[0065] at least one camera, in particular a 3D camera, for detecting the patient lying on the patient bed, and / or

[0066] - at least one radar sensor for detecting a patient located on said patient bed,

[0067] Therein, the control device is designed to determine the activity information by additionally using the video data of the camera and / or the radar data of the radar sensor.

[0068] In this embodiment, different ways of determining the activity information are combined in order to allow, for example, statistical summaries and / or mutual plausibility checks. In other words, additional image data and / or radar data of a camera that is usually always present at the patient can be evaluated in order to improve the detection, localization and quantification of the patient's activities. In this case, it is particularly advantageous to use a three-dimensional camera, for example a TOF camera, a stereo camera and / or a terahertz camera, in order to scan the patient three-dimensionally and determine the activities.

[0069] In principle, it is of course also possible to use other information sources and / or movement information determined in another way, for example navigator measurements of a magnetic resonance system, electrocardiogram measurements, movement information from a respiratory belt, etc., in order to improve the quality of the movement information.

[0070] Other sensor devices, such as cameras and / or other information sources may also be used to at least partially determine the above-mentioned background information.

[0071] In addition to the measuring device, the present invention also relates to a magnetic resonance device, which has the measuring device according to the present invention. As mentioned above, the method provided here is particularly advantageously applied to magnetic resonance imaging for determining patient activity information caused by long measurement times and a harsh electromagnetic environment. All the descriptions of the measuring device according to the present invention also apply to the magnetic resonance device according to the present invention, so that the aforementioned advantages can also be achieved with the magnetic resonance device. It is particularly advantageous here that at least one stress sensor on the patient's bed can be implemented as part of the insertion channel, for example, so that the detection of activity can be achieved without changing other devices, especially the local coil device.

[0072] In particular, a patient bed having a second fastening element for accommodating a first fastening element of a fastening belt is also conceivable within the scope of the present invention as a retrofit component, wherein the second fastening element has a strain sensor for measuring the tensile force of the fastening belt introduced from the first fastening element to the second fastening element. With such a patient bed, it is possible to retrofit an existing magnetic resonance system or other medical surgical and / or examination device particularly easily and without replacing auxiliary components (e.g., a local coil device) in order to determine the movement information and, in addition, to evaluate the sensor data of the strain sensor regarding the movement information when a control device of the magnetic resonance system or other medical device is updated accordingly.

[0073] Finally, the invention also relates to a method for operating a measuring device according to the invention, wherein activity information describing the patient's activity is determined from the sensor data of the stress sensor by means of a control device. The method is ultimately used to measure the activity of a patient who is positioned in a supine position on a patient bed. All that has been described with respect to the measuring device according to the invention and the magnetic resonance device according to the invention can be transferred analogously to the method according to the invention, so that the advantages described can also be achieved with the method. After the method has been carried out by means of a control device, it is in particular computer-implemented.

[0074] Accordingly, also within the scope of the invention are conceivable computer programs which, when executed on a control device of a measuring device, cause the control device to carry out the steps of the method according to the invention. The computer program can be stored on an electronically readable data medium. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] Further advantages and details of the invention are apparent from the exemplary embodiments described below and with reference to the accompanying drawings. In the drawings:

[0076] Figure 1 shows a view of a patient arranged on a patient bed in a first exemplary embodiment of the measuring device according to the invention,

[0077] Figure 2 A possible design of the fixing belt is shown.

[0078] Figure 3 A magnetic resonance system is shown having a measuring device according to the invention,

[0079] Figure 4 A schematic diagram showing an insertion channel with a fixing strap,

[0080] Figure 5 Show Figure 4 A schematic side view of a section through the insertion channel in FIG.

[0081] Figure 6 A view showing a patient bed in a magnetic resonance device, and

[0082] Figure 7 A schematic diagram shows a local coil arrangement in a second exemplary embodiment of a magnetic resonance system according to the present invention. DETAILED DESCRIPTION

[0083] Figure 1 The schematic diagram of a patient 1 is shown, which is arranged on a patient bed 2 according to a first embodiment of a measuring device 3 according to the invention. As shown in the figure, a local coil arrangement 5 is arranged as an auxiliary device 4 on the chest of the patient 1 who is positioned in a supine position, and is intended to be held in position by means of a fixing belt 6 during a magnetic resonance measurement.

[0084] In the first embodiment, the fixing strap 6 is not part of the local coil device 5 but is arranged separately from it. Figure 2 Specifically shown. Accordingly, the fixing belt 6 here includes two sub-belts 7, which are connected by an adjusting member 8 to adjust the belt length that can be used for fixing. The adjusting member here is a buckle device that can move and fix the sub-belt 7. Of course, other designs can also be considered, such as using a single belt member for the fixing belt 6, which can be adjusted in terms of its belt length that can be used for fixing by means of the adjusting member 8.

[0085] The fixing strap 6 has first fastening elements 9, which are plug elements in this case, at the two free ends facing away from the adjusting element 8. Figure 1 The plug piece, i.e. the first fastening element 9, can cooperate with the second fastening element 10 on the patient bed side to fasten the fixing belt 6 to the patient bed 2, wherein the second fastening element is configured as an insertion channel 12 arranged in the patient support surface 11. Since such second fastening elements 10 are arranged on both sides of the patient 1 in the lateral direction, i.e. on the left and right sides of the patient bed 2, the fixing belt 6 can be fastened on both sides with its corresponding first fastening element 9, so that the stress formed thereby is sufficient to keep the local coil device 5 in its current position and orientation during the magnetic resonance examination without causing any inconvenience to the patient 1.

[0086] The fixing belt 6 is designed to be inextensible, that is to say in particular at least substantially inelastic. This means that the tensile forces introduced into the fixing belt 6 by the movement of the patient 1 directly or indirectly via the local coil device 5 are transmitted via the fixing belt 6 to the rigid first fastening element 9, where the tensile forces are further transmitted to the second fastening element 10, which here respectively comprises (at Figure 1 At least one stress sensor (not shown for simplicity) is used, and the stress sensor collects sensor data through tension by means of deformation of a measuring element. The measuring element can be equivalent to a sensor element of each stress sensor or be provided with a sensor element. The sensor data can be evaluated as activity information describing the activity of the patient 1, as will be described in detail below.

[0087] It should be noted that embodiments are also conceivable in which different fixing straps 6 are fastened to at least a part of the auxiliary device 4 by means of a fastening device, in particular from both sides, in order to achieve in this way a fixation of the auxiliary device 4 in the corresponding position (and thus a partial fixation of the patient 1). The advantage of a separate fixing strap 6 with a first fastening element 9 on both sides is that it can be directly tensioned by the patient 1 even without the auxiliary device 4, so that even without the auxiliary device 4, the tensile forces resulting from the movement can be transmitted to the second fastening element 10 of the patient bed 2. Thus, for example, during a magnetic resonance measurement of the head of the patient 1, the breathing can be measured with the aid of the fixing strap 6 in the chest area; moreover, even in rigid, housing-like local coil arrangements, such as head coils and knee coils, it is possible to achieve movement measurements, for example by rigidly adjoining a local coil arrangement that is not adjusted to the patient's morphology, with one fixing strap 6 extending directly through the patient 1 with a certain tension that does not cause discomfort to the patient 1.

[0088] Figure 3 By way of example, a possible way of using an auxiliary device 4, here a local coil arrangement 5, along a patient 1 for a whole-body examination with a magnetic resonance system 13, which includes a measuring device 3. The magnetic resonance system 13 includes a main magnet unit 14 with a patient accommodation 15, into which a patient bed 2 can be introduced. With the aid of individual fixing straps 6 distributed along the length of the patient, active measurements can be carried out at different locations, in particular also at locations where no measurements are taking place, i.e. outside the homogeneous volume.

[0089] Figure 4 and Figure 5 The schematic diagram shows in more detail how the stress sensor 16 is integrated in the second fastening element 10. Figure 4 A schematic side view of a first fastening member 9 connected to a second fastening member 10 is shown, and Figure 5 It shows Figure 4 Schematic cross section of the situation.

[0090] Here, the insertion channel 12 has an insertion slot 17, which widens toward the cavity below the measuring element 18, which acts as a sensor element 19 and can be deformed accordingly to a certain extent, and the fastening element 20 of the first fastening part 9, here a latching pin 21, is firmly embedded in the cavity, so that at least the top side of the latching pin 21 abuts against the bottom side of the measuring element 18 and thus prevents the first fastening part 9 from coming out of the insertion slot 17. In order to be able to release the connection again, a corresponding release piece or the like for withdrawing the latching pin 21 can be provided, as is known in the prior art in a variety of designs.

[0091] The fixing belt 6 is fixed as described above, so that there is a certain tension, so that the fastening element 20 is firmly against the measuring element 18. If the patient 1 moves, such as Figure 4 As shown by arrow 22, a tensile force is generated, which, due to the at least substantially inextensible fastening strap 6 and the rigid first fastening element 9, is transmitted to the latching pin 21 or the fastening element 20, where the pressure of the fastening element 20 against the measuring element 18 is changed by the tensile force, which leads to a deformation of the measuring element 18 and at the same time to a deformation of the sensor element 19, which is measured by the strain sensor 16. For the sake of clarity, in Figure 4 This deformation is shown by the dashed line 23 in FIG.

[0092] In this exemplary embodiment, an optical fiber sensor is used as the stress sensor 16, which therefore uses at least one sensor element 19 which is also Figure 5 In this case, the sensor element 19 uses a distributed fiber Bragg grating (FBG) as described above, so that spatially resolved measurements can be achieved and it can be determined in the sensor data where the tensile force or tensile force change indicated by the arrow 22 acts. It is particularly expedient to insert a plurality of first fastening elements 19 along a channel section of the insertion channel 12 in which the measuring element 18 extends, which is achieved by free selection of the insertion position.

[0093] When using fiber-optic sensors which provide spatially resolved sensor data, it is generally advantageous if the entire length of the (even outer) insertion channel 12 is covered by a single measuring element 18. Figure 4 and Figure 5 Although shown by way of example, it is also conceivable, however, to provide a plurality of measuring elements 18 and thus a plurality of strain sensors 16 along at least one insertion channel 12 of the patient bed 2 , each covering a channel section.

[0094] In this case, Figure 6Schematically illustrate the stereogram of the patient's bed 2 observed from above. As shown in the figure, outside on the right and left sides, as the second fastener 10, an insertion channel 12 extending at least substantially on the entire use length of the patient's bed 2 is provided. In the region where the head of the patient 1 is positioned, two other insertion channels 12 are shown here. Correspondingly, other shorter insertion channels 12 can also be arranged in the region of the arm / hand and / or in the region of the leg / foot, but are not shown for the sake of simplicity. For the shorter insertion channel 12, only a single measuring element 18 and thus a single stress sensor 16 are provided for the entire length of the insertion channel 12, compared with it, the external insertion channel 12 is then divided into four channel sections, wherein each has a measuring element 18, so each channel section includes a separate stress sensor 16.

[0095] It is particularly expedient here to carry out measurements on at least two sides of the patient 1 , ie the right side and the left side, in order to obtain a coherent overall picture from the sensor data, which, in addition to allowing a more precise determination of the patient's movements, can also be plausibly verified.

[0096] For simplicity Figure 6 Only the control unit for the stress sensor 16 of the external right insertion channel 12 is shown, the sensor data of the stress sensor 16 being determined in a control unit 25 comprising electronic components, here by a corresponding light signal in the sensor element 19, more precisely in the optical fiber 24, which light signal can be generated, for example, by a laser and measured by a photodetector. The control unit 25 can also be installed in the patient bed 2 and provides its sensor data so that the transmitting stress sensor 16 can be identified, which is further transmitted via the bus 26 to the control device 27, which determines the activity information from the sensor data, in particular in combination with and taking into account its source. In this case, the control device 27 is the control device of the magnetic resonance device 13.

[0097] The control device 27 has a memory 28 and at least one processor (not shown in detail). For evaluation, the control device 27 can include at least one evaluation unit, by which at least one evaluation function is applied to the sensor data as input data in order to obtain activity information as output data.

[0098] However, before the sensor data are evaluated, the sensor data are corrected due to compensation information in the memory 28 regarding interference caused by components of the magnetic resonance system, in particular the gradient coils. A correction unit can be provided for this purpose. Vibrations can be introduced into the patient bed 2 by the gradient coils of the gradient coil arrangement of the magnetic resonance system 13, which vibrations can also be measured. Therefore, in the calibration measurement, the compensation information is already acquired by the strain sensor 16 without the patient 1 and with the gradient coils operated with certain operating parameters, so that the correction unit can remove the corresponding interference terms in the sensor data, for example by subtraction.

[0099] Within the scope of the evaluation, the activity information is preferably determined so that it describes the intensity and location of the movement of the patient 1 for at least one activity type. For example, the at least one activity type may include periodic activity types, such as breathing activity and / or activity due to the heartbeat, and / or involuntary activity types, such as muscle spasms, and / or conscious activity.

[0100] Particularly preferably, a trained evaluation function is used in order to detect and separate different types of activity and to be able to determine their intensity and / or their location. The trained evaluation function can be trained in a training phase using a training data set in which the sensor data of the stress sensor 16 (as training input data) can be matched to ground truths (as training output data), for example acquired by other measuring devices. Preferably, reinforcement learning is used, in particular in combination with electrocardiographic and respiration measurements, in particular when monitoring periodic activity types.

[0101] The control device 27 also serves as a control device for the magnetic resonance system 13 and can use the activity information in various ways and methods, for example to trigger a recording process during a time period without activity, to mark magnetic resonance data affected by activity and / or to perform activity correction on the recorded magnetic resonance data.

[0102] It should also be noted here that the specific embodiment of the measuring device 3 described here can also be varied. For example, instead of the (extended) cavity 19, a groove can be provided in the measuring element 18, which accommodates the fastening element 20, so that forces can be transmitted and measured, for example, in two directions.

[0103] If the measuring element 18 itself does not form the sensor element 19 , the sensor element 19 can be applied to the measuring element 18 from a soft, ductile material, in particular in the form of a strip.

[0104] In addition, other types of stress sensors 16 can also be used, such as conventional rheological and / or capacitive stress sensors and / or stress sensors using piezoelectric materials. However, preferably, in the field of magnetic resonance, optical fiber stress sensors 16 are used, wherein, in addition to the described design with distributed fiber Bragg gratings, designs with ductile optical fibers are also conceivable.

[0105] Other types of arrangements of the strain sensor 16 are also possible, in particular using the sensor element 19 on the fastening strap 6 .

[0106] In this case, Figure 7 As an essential component of a second exemplary embodiment of a measuring device 3, a local coil arrangement 5 is shown, to which four fastening straps 6 (two on each side) are fastened by means of fastening devices 29, at the other ends of which first fastening elements 9 are arranged. The local coil arrangement 5 also has an electrical connection cable 30, which includes a corresponding coil plug 31.

[0107] The sensor element 19 of the strain sensor 16 is here applied to the fixing band in the extensible part of the fixing band 6 or is integrated in the fixing band. The control unit 25 of the strain sensor 16 is designed as a component of the electronic unit 25 of the local coil arrangement 5, wherein a fastening device 29 is provided for easily establishing a wired communication connection between the sensor element 19 and the control unit 25.

[0108] In addition to the wired transmission path between the sensor element 19 and the control unit 25, wireless communication can also be used in other embodiments, wherein the sensor element 19 is arranged on the fixing belt 6. As shown in the figure, the sensor element 19 is at least conveniently arranged adjacent to the fastening device 29.

[0109] Furthermore, a similar design can also be realized on the patient bed 2, in which the first fastening element 9 is arranged adjacent to the sensor element 19. In this case, the control unit 25 can be arranged, for example, on the side of the second fastening element or adjacent to the second fastening element.

[0110] Finally, it should also be noted that additional measuring means or information sources, such as background information in this case, can also be taken into account by control device 27. In particular, it is conceivable that the activity information is also determined in other ways and combined with the activity information of strain sensor 16 statistically or for plausibility verification.

[0111] For example, the measuring device 1 may also include at least one Figure 3The camera 33 shown in the figure is preferably a three-dimensional measuring camera, from whose image data the actual movement information can be determined, since it detects the patient 1. However, it is also possible to determine background information with the aid of the image information of the camera 33 in order to determine movement information from the sensor data of the strain sensor 16, for example which fixation belt 6 is arranged where, how the fixation belt is extended, etc.

[0112] Although the details of the present invention have been illustrated and described in detail through the preferred embodiments, the present invention is not limited to the disclosed examples, and those skilled in the art may derive other different variations therefrom without departing from the scope of protection of the present invention.

Claims

1. A measuring device (3) for measuring the movement of a patient (1) positioned in a supine position on a patient bed (2), in particular in a magnetic resonance device (13), the measuring device comprising: - The patient is bedridden (2), and - at least one flexible fixing belt (6) for partially fixing the patient (1) on the patient bed (2), wherein the fixing belt (6) has at least one first fastening element (9) which cooperates with a second fastening element (10) of the patient bed (2) in order to fasten the fixing belt (6), It is characterized in that at least one stress sensor (16) which is designed as a component of the fixing strap (6) and / or is movably coupled to the fixing strap, and A control device (27) for determining movement information describing the movement of the patient (1) based on the sensor data of the strain sensor (16).

2. The measuring device according to claim 1, characterized in that The measuring device (3) also has an auxiliary device (4) arranged on the patient (1) and fixed thereto, at least two of the plurality of fixing straps (6) being fastened to the auxiliary device by means of a fastening device (29) via ends opposite to the first fastening element (9), and / or at least one of the at least one fixing strap (6) having a first fastening element (9) on both sides, the first fastening element being used for mutually opposite second fastening elements (10) of the patient bed (2).

3. The measuring device according to claim 1 or 2, characterized in that The sensor element (19), in particular a strain gauge, of the stress sensor (16) is arranged on an elastic portion of at least one of the at least one fixing straps (6).

4. The measuring device according to claim 1 or 2, characterized in that The fixing belt (6) has an adjusting piece (8) for adjusting the belt length of the fixing belt (6), and / or the fixing belt is inelastic.

5. The measuring device according to any one of the preceding claims, characterized in that At least one of the at least one stress sensor (16) is arranged at the first and / or second fastener (9, 10).

6. The measuring device according to claim 5, characterized in that The first fastening component (9) has a fastening element (20), in particular a locking element, which in the fastened state abuts against a measuring element (18) of the second fastening component (10), wherein the measuring element (18) is designed as a sensor element (19) of a strain sensor (16), or the sensor element (19) of the strain sensor (16) is arranged on the measuring element (18).

7. The measuring device according to claim 6, characterized in that The second fastening member (10) is configured as an insertion channel (12) for inserting the first fastening member (9) into any position covered by the insertion channel (12), in particular in the longitudinal direction of the patient bed (2).

8. The measuring device according to claim 7, characterized in that The measuring element (18) delimits an insertion slot (17) of the insertion channel (12) and delimits a cavity which is widened relative to the insertion slot (17) and is designed to accommodate a fastening element (20).

9. The measuring device according to claim 7 or 8, characterized in that The measuring element (18) and / or the sensor element (19) covers the entire length of at least one of the at least one insertion channel (12), or at least one of the at least one insertion channel (12) has a plurality of measuring elements (18) and / or a plurality of sensor elements (19) for a plurality of different channel sections occupying the entire length of the insertion channel (12).

10. The measuring device according to claim 9, characterized in that The strain sensor (16) is designed to measure in a spatially resolved manner the effect of a fastening element (20) on a measuring element (18), and is in particular designed as a fiber-optic sensor having a fiber Bragg grating.

11. The measuring device according to any one of the preceding claims, characterized in that The strain sensor (16) has an optical fiber (24) as a sensor element (19) with a measurement signal carrier, in particular a sensor element (19) based on an expandable optical fiber and / or a fiber Bragg grating sensor element (19).

12. The measuring device according to any one of the preceding claims, characterized in that The control device (27) compensates the sensor data for movements, in particular vibrations, caused by the operation of components of the magnetic resonance system (13), in particular gradient coils, on the basis of compensation information obtained in calibration measurements.

13. The measuring device according to any one of the preceding claims, characterized in that The control device (27) is designed to determine the activity information using a trained evaluation function which uses the sensor data as input data.

14. The measuring device according to any one of the preceding claims, characterized in that The measuring device also includes: - at least one camera (33), in particular a three-dimensional camera, for detecting the patient (1) lying on the patient bed (2), and / or - at least one radar sensor for detecting a patient (1) located on the patient bed (2), The control device (27) is designed to determine the activity information by additionally using the video data of the camera (33) and / or the radar data of the radar sensor.

15. A magnetic resonance device (13) comprising a measuring device (3) according to any of the preceding claims.

16. A method for operating a measuring device (3) according to any one of claims 1 to 14, wherein: Movement information describing the movement of the patient (1) is determined using sensor data from the stress sensor (16) by means of a control device (27).

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