Demand-oriented functional tests for the efficient detection of sporadic errors based on a patient-specific risk assessment

Abstract

The invention relates to methods for performing a magnetic resonance examination of a patient using a magnetic resonance device, to a magnetic resonance device, and to a computer program product. According to the method, patient-specific information about the patient is provided. Based on the patient-specific information about the patient, it is determined whether at least one latent error test of the magnetic resonance device needs to be performed. If the determination shows that the at least one latent error test needs to be performed to check the magnetic resonance device, the at least one latent error test is performed. The magnetic resonance examination is performed depending on a result of the at least one latent error test.

Description

[0001] The invention relates to a method for performing a magnetic resonance examination of a patient using a magnetic resonance device, a magnetic resonance device and a computer program product.

[0002] During a magnetic resonance examination of a patient, i.e., during magnetic resonance imaging (MRI), magnetic fields, particularly gradient fields, and radio-frequency signals or radio-frequency fields are typically used to acquire magnetic resonance signals using a magnetic resonance device according to a measurement protocol. To generate the gradient fields, the magnetic resonance device typically has a gradient coil unit. Furthermore, the magnetic resonance device typically includes a radio-frequency antenna unit, with which the radio-frequency signals can be generated to excite atomic nuclei.

[0003] As the performance of the magnetic resonance device increases with regard to gradient strength and radiofrequency power, risks for the patient may arise, e.g. through stimulation of the patient's heart muscle as a result of induced tension in the tissue by strong temporal magnetic field gradients and / or overheating of the patient's tissue due to strong radiated radiofrequency power.

[0004] To make matters worse, any implants in the patient's body can locally concentrate both magnetic fields and radiofrequency fields, particularly through their passive antenna function. This can lead to a local field amplification, so that higher field strengths can occur in the patient's body than in the case without an implant.

[0005] If a serious risk exists (e.g., serious injury or death of a single person), appropriate mitigation measures must be implemented, particularly if the probability of occurrence is unacceptably high. These measures aim to reduce the probability of occurrence and / or the severity of the risk.

[0006] One possible way to implement a mitigation measure is to check a control path that controls the patient's magnetic resonance examination in a separate test path, often also called a protect path. The task of the control path is to specify or influence a target value of a control variable, e.g., for controlling the gradient coil unit and / or radio-frequency antenna unit. The document DE102020206063A1 discloses, by way of example, a magnetic resonance device with one control path and two protect paths.

[0007] In the test path, an actual value measured at a given time is recorded (ideally completely independently) and compared with the target value. If there is a deviation between the target value and the actual value, an appropriate error response is triggered. Typically, the so-called safe state is assumed, which usually means a controlled measurement abort. However, it is possible that a failure of the test path is not immediately detectable. This can lead to undetected, latent errors, for example, the test path no longer correctly fulfills its test function due to a sensor error.

[0008] To detect these latent errors, so-called latent error tests are performed on the magnetic resonance imaging device at regular intervals, during which the functionality of the test path is explicitly triggered. For example, target values can be deliberately set that exceed permissible limits, thereby triggering the test path. The time required to perform such a latent error test can easily be in the range of minutes. Therefore, from the user's perspective, it is highly desirable to plan the tests in such a way that they have no or minimal impact on patient operations.

[0009] Document DE 102020214736 A1 discloses a method according to which an error monitoring device compares a system state with a predetermined target state and enables a function of the medical device depending on the comparison. Document DE 102016206398 A1 discloses a method for operating a magnetic resonance device taking implant wearers into account.

[0010] The object of the present invention can be considered to improve the correct, in particular safe, operation of a magnetic resonance device or the performance of a magnetic resonance examination. This object is achieved by the features of the independent claims. Advantageous embodiments are described in the dependent claims.

[0011] A computer-implemented method for performing a magnetic resonance examination of a patient using a magnetic resonance device is proposed. Patient-specific information about the patient is provided. Based on the patient-specific information about the patient, it is determined whether at least one latent error test of the magnetic resonance device needs to be performed. If the determination shows that the at least one latent error test needs to be performed to check the magnetic resonance device, the at least one latent error test is performed. The magnetic resonance examination is performed depending on the result of the at least one latent error test.

[0012] For example, the patient-specific information about the patient is provided by a provision unit. For example, the determination of whether at least one latent error test of the magnetic resonance device needs to be performed is provided by a determination unit. The provision unit and / or the determination unit can, in particular, comprise one or more processors and / or one or more memory modules. The provision unit and / or the determination unit can, in particular, be part of a system control unit of the magnetic resonance device.

[0013] The determination of whether at least one latent error test of the magnetic resonance device is to be carried out preferably comprises the determination of a patient-specific risk that can be mitigated by the at least one latent error test, based on the patient-specific information. In particular, it is determined whether a patient-specific risk exists that requires functionally safe monitoring. The patient-specific risk of the magnetic resonance examination is preferably determined depending on a probability of error occurrence (e.g., low, medium, or high probability) and / or a severity of the consequences of the error (e.g., minor injury, serious injury, or even death of the patient). The higher the probability of error occurrence and / or the severity of the consequences of the error, the more likely it is that at least one latent error test will be carried out.For example, if multiplying a measure of the probability of failure by a measure of the severity of failure results in a value that is above a predetermined threshold, a latent failure test must be carried out to check the magnetic resonance device.

[0014] Advantageously, the patient-specific or needs-based execution of latent error tests minimizes the interruption of regular operation of the magnetic resonance imaging system. However, in contrast to the prior art, the latent error tests are performed at regular intervals, regardless of the patient-specific risk. The proposed method can therefore reduce the overall time required to perform the latent error tests. The method is particularly advantageous when the risk mitigated by at least one latent error test is relevant only for a relatively small proportion of patients and this patient group is not evenly distributed across the patient population.

[0015] Advantageously, the magnetic resonance examination is only carried out if the result of the at least one latent error test indicates correct, in particular safe, operation of the magnetic resonance examination and / or correct, in particular safe, performance of the magnetic resonance examination.

[0016] Preferably, the at least one latent error test determines whether at least one test path of the magnetic resonance device is functioning correctly. For example, a positive result of the at least one latent error test ensures that any sensors in a test path of the magnetic resonance device are functioning correctly. If the result of the latent error test were, for example, that a sensor in the test path had failed, then preferably no magnetic resonance examination of the patient would be performed.

[0017] The at least one test path is preferably configured to test at least one control path of the magnetic resonance device during the magnetic resonance examination, in particular a magnetic resonance measurement. The at least one test path comprises, in particular, elements that contribute to monitoring the safety-relevant function. For example, the at least one test path comprises sensors and / or detectors for detecting at least one safety-relevant parameter of the magnetic resonance device. The at least one safety-relevant parameter can, in particular, comprise safety-relevant system variables of the magnetic resonance device, for example, a gradient current.

[0018] The at least one control path of the magnetic resonance device is preferably configured to specify or influence a target value of a control variable, e.g., for controlling the gradient coil unit and / or radio-frequency antenna unit. In the test path, an actual value measured at the respective time is recorded (ideally completely independently) and compared with the target value. If there is a deviation between the target value and the actual value, a corresponding error response is triggered. Typically, the so-called safe state is assumed, which usually means a controlled termination of the examination, in particular a measurement termination.

[0019] Preferably, the patient-specific information includes information about the patient's implant. For example, the information about the patient's implant includes at least one limit value to be observed. The at least one limit value to be observed can, for example, include a maximum gradient slew rate. The severity of the error consequences for patients with implants can, in particular, be significantly higher than for patients without implants.

[0020] For example, there are patients who wear an implant in the "MR conditional" category. Implants in the "MR conditional" category are products with proven safety in magnetic resonance imaging (MRI) examinations under defined conditions, particularly when certain limits are observed. These limits are often significantly lower than for patients without an implant. This is the case, for example, with patients with pacemakers, for whom the maximum gradient slew rate limit is 125 T / m / s instead of 200 T / m / s. Another example is cochlear implants, which in some cases also have limits well below 200 T / m / s.

[0021] The time savings achieved by the proposed procedure are greater the more sporadic and critical the risks are for individual patients. This is particularly true for relatively rare implants in the "MR conditional" category with maximum gradient slope rates significantly lower than 200 T / m / s.

[0022] Preferably, when carrying out the at least one latent error test, at least one malfunction of the magnetic resonance device to be checked is triggered and it is checked whether the at least one malfunction of the magnetic resonance device to be checked is detected.

[0023] In latent error tests, the functionality of the test path is explicitly triggered. For example, target values can be intentionally set that exceed permissible limits, thereby triggering the test path.

[0024] Preferably, the at least one malfunction to be checked relates to the safety of the patient and / or to a correct functioning of the magnetic resonance device during the magnetic resonance examination.

[0025] In addition to functionally safe monitoring of a control task, patient-specific latent error tests can also be applied to control tasks that are not implemented in a functionally safe manner. The goal is then to reduce the probability of error occurrence by ensuring the correct functioning of the magnetic resonance imaging device before measuring a patient, especially with patient-specific increased risks.

[0026] Preferably, the magnetic resonance examination is performed immediately after the at least one latent error test of the magnetic resonance device has been performed. For particularly critical magnetic resonance measurements, the correct functioning of the magnetic resonance device is advantageously ensured directly before the examination. The probability of failure of monitoring hardware or a test path is typically considerably lower, taking the MTTF (Mean Time To Failure) into account, if correct functioning is ensured directly before the examination rather than at fixed time intervals.

[0027] If the determination indicates that at least one latent error test of the magnetic resonance device is to be performed, the method preferably further comprises determining the at least one malfunction to be checked and / or parameterizing the at least one latent error test of the magnetic resonance device. Advantageously, the at least one latent error test is designed in such a way that it optimally minimizes the patient-specific risk to be mitigated.

[0028] Furthermore, a magnetic resonance device is proposed that is configured to carry out a previously described method for performing a magnetic resonance examination of a patient using the magnetic resonance device. The advantages of the magnetic resonance device essentially correspond to the advantages of the method for performing a magnetic resonance examination of a patient using the magnetic resonance device, which were described in detail above. Features, advantages, or alternative embodiments mentioned herein can also be applied to the other claimed subject matter, and vice versa.

[0029] Furthermore, a computer program product is proposed, which comprises a program and is directly loadable into a memory of a programmable system control unit of a magnetic resonance apparatus and has program means, e.g., libraries and auxiliary functions, for executing a proposed method when the computer program product is executed in the system control unit of the magnetic resonance apparatus. The computer program product can comprise software with a source code that still needs to be compiled and linked or that only needs to be interpreted, or an executable software code that only needs to be loaded into the system control unit for execution.

[0030] The computer program product advantageously allows the proposed method to be executed quickly, identically repeatably, and robustly. The computer program product is preferably configured to execute the proposed method steps using the system control unit. The system control unit has the necessary prerequisites, such as a corresponding RAM, a corresponding graphics card, or a corresponding logic unit, so that the respective method steps can be executed efficiently.

[0031] The computer program product is stored, for example, on a computer-readable medium or stored on a network or server, from where it can be loaded into the processor of a local system control unit, which can be directly connected to the magnetic resonance apparatus or formed as part of the magnetic resonance apparatus. Furthermore, control information of the computer program product can be stored on an electronically readable data carrier. The control information of the electronically readable data carrier can be configured such that, when the data carrier is used in a system control unit of a magnetic resonance apparatus, it carries out a proposed method.

[0032] Examples of electronically readable data storage media include a DVD, a magnetic tape, or a USB flash drive on which electronically readable control information, in particular software, is stored. If this control information is read from the data storage media and stored in a system control unit of the magnetic resonance apparatus, all proposed embodiments of the methods described above can be implemented.

[0033] Further advantages, features, and details of the invention will become apparent from the exemplary embodiments described below and from the drawings. Corresponding parts are provided with the same reference numerals in all figures.

[0034] They show: Fig. 1 a magnetic resonance device in a schematic representation, Fig. 2 a flowchart of a method for performing a magnetic resonance examination of a patient with the magnetic resonance device.

[0035] In Fig. 1 schematically illustrates a magnetic resonance apparatus 10. The magnetic resonance apparatus 10 comprises a magnet unit 11 having a main magnet 12 for generating a strong and, in particular, temporally constant main magnetic field 13. In addition, the magnetic resonance apparatus 10 comprises a patient receiving area 14 for receiving a patient 15. The patient receiving area 14 in the present exemplary embodiment is cylindrical and is surrounded in a circumferential direction by the magnet unit 11. In principle, however, a different design of the patient receiving area 14 is conceivable at any time. The patient 15 can be pushed into the patient receiving area 14 by means of a patient support device 16 of the magnetic resonance apparatus 10. For this purpose, the patient support device 16 has a patient table 17 designed to be movable within the patient receiving area 14.

[0036] The magnet unit 11 further comprises a gradient coil unit 18 for generating magnetic field gradients used for spatial encoding during imaging. The gradient coil unit 18 is controlled by a gradient control unit 19 of the magnetic resonance device 10. The magnet unit 11 further comprises a radio-frequency antenna unit 20, which in the present exemplary embodiment is designed as a body coil permanently integrated into the magnetic resonance device 10. The radio-frequency antenna unit 20 is controlled by a radio-frequency antenna control unit 21 of the magnetic resonance device 10 and radiates radio-frequency magnetic resonance sequences into an examination space, which is essentially formed by a patient receiving area 14 of the magnetic resonance device 10. As a result, the main magnetic field 13 generated by the main magnet 12 excites atomic nuclei.Magnetic resonance signals are generated by relaxation of the excited atomic nuclei. The radio-frequency antenna unit 20 is configured to receive the magnetic resonance signals.

[0037] The magnetic resonance apparatus 10 has a system control unit 22 for controlling the main magnet 12, the gradient control unit 19, and the radio-frequency antenna control unit 21. The system control unit 22 centrally controls the magnetic resonance apparatus 10, such as performing a predetermined imaging gradient echo sequence. The system control unit 22 also includes an evaluation unit (not shown in detail) for evaluating the magnetic resonance signals acquired during the magnetic resonance examination. Furthermore, the magnetic resonance apparatus 10 includes a user interface 23 connected to the system control unit 22. Control information, such as imaging parameters, as well as reconstructed magnetic resonance images, can be displayed on a display unit 24, for example, on at least one monitor, of the user interface 23 for medical personnel.Furthermore, the user interface 23 has an input unit 25 by means of which information and / or parameters can be entered by the medical operating personnel during a measurement process.

[0038] The system control unit 22 comprises a test unit 26, which represents a test path of the magnetic resonance device 10. The test path ensures independent monitoring of the control of the magnetic resonance device, in particular the gradient coil unit 18 and gradient control unit 19, as well as the radio-frequency antenna unit 20 and radio-frequency antenna control unit 21, which represent a control path (or a part thereof). Advantageously, the test unit 26 detects whether any limit values are exceeded by the gradient coil unit 18 and gradient control unit 19, or by the radio-frequency antenna unit 20 and radio-frequency antenna control unit 21. These limit values can, in particular, relate to the safety of the patient 15, such as a SAR exposure (SAR: Specific Absorption Rate) and / or a PNS exposure (PNS: Peripheral Nerve Stimulation). The patient 15 here comprises an implant 27.This may result in higher requirements for patient safety, i.e. the maximum permitted limits may be lower.

[0039] In Fig. 2 shows a possible sequence of a method for performing a magnetic resonance examination of the patient 15 with the magnetic resonance device 10.

[0040] In S1, the patient 15 is registered at the magnetic resonance device 10. In the process, for example, information about the patient 15 is acquired. The acquisition of the information about the patient 15 can, for example, be carried out by an operator of the magnetic resonance device 10 with the aid of the user interface 23. The information about the patient 15 can, for example, include the height, weight, age, gender and / or other characteristics of the patient 15. Such further characteristics can, in particular, include whether the patient 15 is wearing an implant 27 or not. In particular, a type of implant, e.g., "MR conditional," and / or limit values to be observed, e.g., for B1+rms, SAR, gradient slew rate, static field gradient, can be acquired.

[0041] Some or all of this acquired information about the patient 15 can be provided as patient-specific information in S2. In S3, based on the patient-specific information provided in S2, it is determined whether at least one latent error test is to be performed to check the magnetic resonance device, y, or not, n.

[0042] In particular, S3 determines whether patient-specific risks exist that require functionally safe monitoring and / or verification. If so, S4 determines the latent error tests to be performed as needed. These latent error tests are then parameterized in S5 and performed in S6.

[0043] In the latent error test, for example, a potential malfunction and / or exceeding of a limit value of the magnetic resonance device 10 to be checked is intentionally triggered, and then it is checked whether the malfunction or exceeding of the limit value is also detected. The malfunction being checked can, in particular, affect the safety of the patient 15 and / or the correct functioning of the magnetic resonance device 10 during the magnetic resonance examination.

[0044] Depending on the result of these latent error tests, the magnetic resonance examination will be continued or not in S7. If it is continued, further preparations for the magnetic resonance measurement can be performed in S7, for example, before the actual magnetic resonance examination, in particular the magnetic resonance measurement, of patient 15 is performed in S8.

[0045] Advantageously, the magnetic resonance examination is performed in S8, provided that the result of the latent error test indicates safe operation of the magnetic resonance device 10, immediately after determining the result in S6 and, if necessary, further preparations for the magnetic resonance measurement in S7. The probability of failure of the monitoring hardware under consideration is significantly lower if correct function is ensured directly before the examination and not at fixed time intervals, such as a specific number of days.

[0046] The proposed method provides a key advantage for system functions, which can result in a very different risk assessment for different patient groups.

[0047] A specific application variant of the method presented in Figure S2 will be described in more detail below. This involves a magnetic resonance imaging examination of patient 15 wearing an implant in the "MR conditional" category. In such a measurement, the gradient slope rate is limited.

[0048] The vast majority of implants in the "MR conditional" category, where a limitation of the gradient slew rate is required, have a monitoring limit of 200 T / m / s. According to the data sheet, common magnetic resonance devices today often have an achievable maximum gradient slew rate of 200 T / m / s.

[0049] In such a case, when additional factors such as manufacturing tolerances and power supply fluctuations are taken into account, the probability of serious patient harm during magnetic resonance imaging (MRI) examinations is comparatively low. Therefore, latent error testing may not be required for this type of MRI examination.

[0050] However, if a patient is treated with an implant in the "MR conditional" category, which has a significantly lower limit, for example 100 T / m / s, the situation changes. In this case, in the event of a system malfunction, the permissible implant limit may not only be exceeded due to manufacturing tolerances and fluctuations in the power supply, but the magnetic resonance device 10 is, due to its design, capable of exceeding the permissible limit of 100 T / m / s by 100 percent in the event of an initial error. Patient-specific characteristics may therefore result in a different risk assessment. The method described here can advantageously ensure that, in this case, the correct functionality of the limit value monitoring is ensured before the measurement is performed with the aid of a latent error test carried out on an as-needed basis.

[0051] Finally, it should be noted once again that the methods described in detail above and the magnetic resonance device illustrated are merely exemplary embodiments that can be modified in a variety of ways by a person skilled in the art without departing from the scope of the invention. Furthermore, the use of the indefinite articles "a" or "an" does not exclude the possibility that the features in question may be present in multiple instances. Likewise, the term "unit" does not exclude the possibility that the components in question consist of several interacting subcomponents, which may also be spatially distributed. Regardless of the grammatical gender of a particular term, this includes persons with male, female, or other gender identities.

Claims

[1] A computer-implemented method for performing a magnetic resonance examination of a patient using a magnetic resonance device, the method comprising: • Providing patient-specific information about the patient, • Determine whether at least one latent error test should be carried out to check the magnetic resonance device, based on the patient-specific information, • if the investigation shows that at least one latent error test must be carried out: ◯ Carrying out at least one latent error test of the magnetic resonance device, ◯ Conducting the magnetic resonance examination depending on the result of at least one latent error test, characterized bythat the determination of whether at least one latent error test is to be carried out comprises the determination of a patient-specific risk of the magnetic resonance examination that can be mitigated by the at least one latent error test on the basis of the patient-specific information. [2] The method of claim 1, wherein the patient-specific information comprises information about an implant of the patient. [3] Method according to claim 2, wherein the information about the patient's implant comprises at least one limit value to be observed, in particular a maximum gradient increase rate. [4] Method according to one of the preceding claims, wherein the patient-specific risk of the magnetic resonance examination is determined as a function of a probability of error occurrence and / or a severity of error consequences. [5] Method according to one of the preceding claims, wherein the at least one latent error test comprises: • Triggering at least one malfunction of the magnetic resonance device to be checked • Checking whether at least one malfunction of the magnetic resonance device to be checked is detected and / or a corresponding reaction is triggered. [6] Method according to claim 5, wherein the at least one malfunction to be checked relates to the safety of the patient and / or a correct function of the magnetic resonance device during the magnetic resonance examination. [7] Method according to one of the preceding claims, wherein the magnetic resonance examination is carried out immediately after the at least one latent error test has been carried out. [8] Magnetic resonance apparatus configured to carry out a method as described above. [9] Computer program product comprising a program and being directly loadable into a memory of a programmable system control unit of a magnetic resonance apparatus, with program means for carrying out a method according to any one of claims 1 to 7 when the program is executed in the system control unit of the magnetic resonance apparatus.

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