Method and system for determining the position of a portable MRI system

Abstract

The effects of RF noise and external magnetic fields on the image quality of a portable magnetic resonance imaging (MRI) system 1 should be avoided. This is achieved by a system and computer-implemented method for determining an optimized position and / or orientation of the portable MRI system 1 for the MR imaging process within a medical environment 2. The system comprises at least one RF noise sensor 3 configured to measure RF noise in the medical environment 2 and provide sensor data; at least one magnetic field sensor 4 configured to measure an external magnetic field in the medical environment 2 and provide sensor data; and a processor unit 5 to which the sensors 3, 4 are connected, the processor unit 5 having at least one memory 6 for storing instructions and at least one processor 7 configured to execute the instructions, the processor unit being configured to perform the following steps by executing the instructions: measuring RF noise and the external magnetic field in the medical environment by the corresponding sensors 3, 4; evaluating the sensor data and generating a spatial distribution of the measured RF noise and / or the measured external magnetic field in the medical environment 2; and determining a position and / or orientation of the portable MRI system 1 in the medical environment 2 for an MR imaging process based on the spatial distribution of the measured RF noise and / or the measured external magnetic field.

Description

[Technical Field]

[0001] The present invention relates to the field of portable magnetic resonance imaging (MRI) systems, and more particularly to a system and computer-implemented method for determining the position and / or orientation of a portable MRI system in a medical environment for an MR imaging process in a manner that minimizes the effects of RF noise and external magnetic fields on the image quality of the portable MRI system. [Background technology]

[0002] Magnetic resonance imaging (MRI) is an essential diagnostic tool in today's healthcare. Until recently, patients requiring an MRI scan had to be transported to a radiology department and carefully positioned inside a large magnet. Conventional MRI scans are challenging for many critically ill patients. For this reason, portable magnetic resonance imaging (MRI) systems have been developed to improve and facilitate rapid clinical diagnosis, designed for use in critical or emergency care settings for patients who would otherwise be unable to receive timely MR head scans. Portable MRI systems are low-field MR systems (B0 < 200 mT) designed for use at the point of care, e.g., at bedside, so they can be easily transported by hospital staff. Such systems are less expensive and do not require large, fixed hospital facilities, including RF-shielded rooms and technical suites, thereby aiming to provide affordable and more accessible MR imaging worldwide. Summary of the Invention [Problem to be solved by the invention]

[0003] Portable MRI systems can be moved around the hospital by hospital staff, connected to a regular mains power source, and used at the point of care, for example, at the patient's bedside. They are also commercially available for use in emergency departments, intensive care units, and operating rooms. Because they operate without an RF-shielded room and in a variety of magnetic fields, image quality can be impaired by RF noise or external magnetic fields, which vary significantly over short distances.

[0004] The radio frequency (RF) coil is an essential MRI hardware component. The RF coil is the antenna of the MRI system and has two functions: first, it excites magnetization by transmitting RF power (Tx coil), and second, it receives signals from the patient (Rx coil) that are used to reconstruct MR images. This signal is typically an order of magnitude smaller than the RF noise emitted by any type of electrical equipment. To provide good image quality, standard MR systems installed in fixed facilities in hospitals are installed in RF-shielded rooms, essentially Faraday cages, which prevent RF noise from entering. These rooms are equipped with copper-layered walls, special translucent windows with fine copper mesh, and doors with thin copper plates that block RF when closed. While this shielding solution is technically optimal, it is very expensive and requires a lot of space. In contrast, portable MRI systems operate in regular patient rooms and are subject to strong RF noise generated by various in-hospital equipment or external RF sources such as radio stations. Without countermeasures, this RF noise can have a devastating impact on the image quality of portable MRI systems.

[0005] MR systems installed in fixed facilities in hospitals are usually protected from magnetic field disturbances by two mechanisms: First, such MR systems are equipped with superconducting coils and self-shielding mechanisms, both of which reduce the influence of external magnetic fields on the imaging field of view. Second, care is taken in selecting the location of the MR system to avoid locations where strong magnetic field disturbances occur (e.g., elevators, high-power electrical equipment, cables, etc.). In contrast, portable MRI systems are subject to external magnetic field disturbances that can significantly degrade image quality.

[0006] It is important to note that both RF noise and magnetic field disturbances vary greatly depending on the location within a hospital. In the case of RF noise, this is particularly due to hospital equipment that emits RF noise. Operating a portable MRI system in close proximity to such sources can result in significant image noise, making imaging impossible. Moving a portable MRI system several meters away from such sources significantly reduces RF noise, so standard noise suppression techniques and partial RF shielding by the portable MRI system are sufficient for MR imaging. The same localized characteristics apply to magnetic fields. High-power electrical equipment, such as elevators, electric motors in other heavy equipment like electric vehicles, and their power cables, generate magnetic fields that impair the image quality of portable MR systems. However, these fields are also highly localized and decay rapidly with distance.

[0007] US 2022 / 308140 A1 discloses a magnetic resonance apparatus that may have at least one sensor and a controller. The magnetic resonance apparatus can be arranged in an examination room. The spatial location of the magnetic resonance apparatus in the examination room can be determined using the sensor. In a method for supporting adjustment of shim parameters of a magnetic resonance apparatus, a current spatial location of the magnetic resonance apparatus in the examination room is determined using the sensor, and shim parameters of at least one shim element of the magnetic resonance apparatus are determined based on the current spatial location of the magnetic resonance apparatus and information in a magnetic field database. The magnetic field database can include information on the spatial location of the magnetic resonance apparatus and magnetic field data correlated with the spatial location.

[0008] It is an object of the present invention to provide a system and method for determining the optimal position and / or orientation of a portable magnetic resonance imaging (MRI) system for an MR imaging process in a medical environment subject to high frequency noise and / or external magnetic fields. [Means for solving the problem]

[0009] According to the invention, this object is addressed by the subject matter of the independent claims. Further embodiments of the invention are set forth in the dependent claims.

[0010] According to a first aspect of the present invention, there is provided a system for determining an optimized position and / or orientation of a portable magnetic resonance imaging (MRI) system for an MR imaging process in a medical environment affected by RF noise and / or external magnetic fields. Determining such an optimized position and / or orientation of a portable MRI system, in the context of the present invention, means determining the best or best possible position and / or orientation for the MR imaging process to be performed, minimizing the effects or influences from RF noise and / or external magnetic fields present in the medical environment in which the MRI system is located. When the MR imaging process is performed in such an optimized position and / or orientation, image quality is improved. The system includes at least one RF noise sensor configured to measure RF noise in a medical environment and provide sensor data, at least one magnetic field sensor configured to measure an external magnetic field in the medical environment and provide sensor data, and a processor unit, the sensors connected to the processor unit, the processor unit having at least one memory for storing instructions and at least one processor configured to execute instructions including: measuring RF noise and / or the external magnetic field in the medical environment with a corresponding sensor; evaluating the sensor data and creating a spatial distribution of the measured RF noise and / or the external magnetic field in the medical environment; and determining a position and / or orientation of a portable MRI system in the medical environment for an MR imaging process based on the spatial distribution of the measured RF noise and / or the measured external magnetic field. The term external magnetic field refers to any magnetic field not generated by the coils of the portable MRI system. In particular, various electrical devices such as devices with wireless communication capabilities, computer hardware, and small electric motors can emit RF noise, while devices such as elevators, electric carts, hospital beds, and high-power electric motors can emit external magnetic fields.

[0011] In a technically advantageous embodiment of the system, the at least one RF noise sensor and / or the at least one magnetic field sensor are distributed within the medical environment, which has the advantage that sensors can be installed at key locations where RF noise and / or external magnetic fields are expected to occur, thereby allowing monitoring of this area of ​​the medical environment.

[0012] In another technically advantageous embodiment of the system, the at least one RF noise sensor and / or the at least one magnetic field sensor are portable sensor devices that are connected to the portable MRI system wirelessly or by cable, which has the advantage that, for example, by moving the portable sensor device, a large area of ​​the medical environment can be measured.

[0013] In another technically advantageous embodiment of the system, the at least one RF noise sensor and / or the at least one magnetic field sensor are handheld or wearable sensor devices suitable for being carried by staff and / or by autonomous, self-driving vehicles. Handheld or wearable sensor devices can identify operation locations previously identified as unsuitable, and such operation locations should likely be avoided if possible. These devices can be carried by staff for mapping purposes, or carried by autonomous vehicles that patrol buildings, for example, at night. They can also help accurately identify noise sources in the vicinity of the portable MRI system.

[0014] In a technically advantageous embodiment of the system, the MR-RF coil of the portable MRI system is configured to be used as an RF noise sensor to measure RF noise. The MR-RF coil of the MRI system is a very sensitive receiving antenna. Therefore, in one embodiment of the present invention, it is proposed to use the MR-RF coil to detect RF noise, for example, during transportation of the system. This has the advantage of being able to detect RF noise with spatial and frequency-dependent reception characteristics that are also relevant for MR imaging. Furthermore, the dual use of MR hardware can save weight, volume, and cost.

[0015] In another technically advantageous embodiment of the system, at least one of the at least one RF noise sensor is a directional RF antenna for measuring RF noise, which can be used to determine the location of a strong RF emitter.

[0016] In a technically advantageous embodiment of the system, the system is configured such that the directional RF antenna is read out by the MR receive chain of the portable MRI system, in this way readout of the directional RF antenna can already be guaranteed by existing hardware.

[0017] In another technically advantageous embodiment of the system, the B0 coil of the portable MRI system is configured to be used as a magnetic field sensor for measuring external magnetic fields, which has the advantage of saving space, weight, and cost for dedicated sensors for such fields.

[0018] In a technically advantageous embodiment of the system, the system comprises at least one sensor for measuring the movement and / or position of the portable MRI system, for example based on any of the known methods for measuring movement (GPS, triangulation, IMU, etc.). This has the advantage that RF noise and magnetic fields can be related to the current location of the system and thus mapped in space. Furthermore, it has the advantage that it allows the velocity of the system to be derived, which can be used when using the B coil as a sensor for external magnetic fields.

[0019] In another technically advantageous embodiment of the system, the system comprises a mapping unit configured to generate an interference map with known and estimated interference strengths based on the measured RF noise and external magnetic field. By providing the interference map through the mapping unit, information is available to assist in determining an optimized location for imaging.

[0020] In a technically advantageous embodiment of the system, the system comprises an MR artifact prediction unit configured to estimate a level of image artifacts in the MR imaging process that will be caused by the estimated interference, which also has the advantage of assisting in determining an optimized position for imaging.

[0021] In a second aspect of the present invention, the object is achieved by a computer-implemented method for determining an optimized position and / or orientation of a portable magnetic resonance imaging (MRI) system for an MR imaging process in a medical environment affected by RF noise and / or external magnetic fields, the method comprising the steps of measuring RF noise in the medical environment by at least one RF noise sensor to provide sensor data and measuring the external magnetic field in the medical environment by at least one magnetic field sensor to provide sensor data, evaluating the sensor data to generate a spatial distribution of the measured RF noise and the measured external magnetic field, and determining a position and / or orientation of the portable MRI system for the MR imaging process based on the spatial distribution of the measured RF noise and / or the measured external magnetic field.

[0022] In technically advantageous embodiments of the present invention, measuring RF noise and external magnetic fields by corresponding sensors in the medical environment comprises measuring RF noise and / or external magnetic fields by sensors distributed in the medical environment, and / or measuring RF noise by an MR-RF coil of a portable MRI system, and / or measuring RF noise by a directional RF antenna, and / or measuring external magnetic fields by a B0 coil of a portable MRI system.

[0023] In another technically advantageous embodiment, the method includes the additional step of generating an interference map having known and estimated interference strengths based on the measured RF noise and external magnetic field. By providing the interference map through the mapping unit, information is available to help determine an optimal position of the portable MRI system for imaging.

[0024] In a technically advantageous embodiment, the method comprises the additional step of estimating the level of image artifacts in the MR imaging process caused by the estimated and known interference, which also has the advantage of assisting in determining an optimized position of the portable MRI system for imaging.

[0025] In a technically advantageous embodiment of the method, the method comprises the additional step of providing live guidance to the portable MRI system operator for positioning and / or orienting the portable MRI system based on the sensor data. By providing live guidance, locations with high interference, i.e., locations that are heavily affected by RF noise and / or external magnetic fields, can be avoided, resulting in improved image quality.

[0026] Thus, by carrying out this method, a user can obtain the benefits of the system from the first aspect of the invention.

[0027] According to a third aspect of the present invention there is provided a computer program adapted, when executed by at least one processing unit, to cause the processing unit to perform the steps of the method according to the second aspect of the present invention.

[0028] According to a fourth aspect of the present invention, there is provided a computer readable medium having stored thereon a computer program element.

[0029] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

[0030] BRIEF DESCRIPTION OF THE DRAWINGS

[0031] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter, but such embodiments do not necessarily represent the full scope of the invention, and reference should therefore be made to the claims and this specification for interpreting the scope of the invention. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a diagram that schematically illustrates a medical environment having a portable MRI system and a system for determining the position and / or orientation of the portable MRI system, in accordance with an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic diagram illustrating an RF signal path of a portable MRI system, in accordance with another embodiment of the present invention. [Figure 3] 1 is a flowchart of a computer-implemented method for determining the position and / or orientation of a portable MRI system in a medical environment, according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0033] FIG. 1 schematically illustrates a medical environment 2 having a portable magnetic resonance imaging (MRI) system 1 and a system for determining an optimized position and / or orientation of the portable MRI system 1, according to an embodiment of the present invention. The MRI system 1, suitable for performing an MR imaging process, is located in the medical environment 2. The portable MRI system 1 can be freely moved within the medical environment 2, thereby exposing the portable MRI system 1 to RF noise and magnetic fields. Therefore, according to an embodiment of the present invention, a system for determining an optimized position and / or orientation of the portable MRI system 1 for an MR imaging process in a medical environment 2 affected by RF noise and / or external magnetic fields is provided. Determining an optimized position and / or orientation of the portable MRI system 1, in the context of the present invention, means determining the best or best possible position and / or orientation of the portable MRI system 1 for an MR imaging process to be performed with minimal effects or influences from the RF noise and / or external magnetic fields present in the medical environment 2 in which the MRI system 1 is located. The quality of the image is improved if the MR imaging process is performed with minimal effects / influences from the mentioned disturbances, or similarly, if the portable MRI system avoids locations with high interference.

[0034] The system for determining an optimized position and / or orientation of the portable MRI system 1 includes at least one RF noise sensor 3 configured to measure RF noise in a medical environment 2 and provide sensor data. The system further includes at least one magnetic field sensor 4 configured to measure an external magnetic field in the medical environment 2 and provide sensor data. The system further includes a processor unit 5, and the sensors 3, 4 are connected to the processor unit 5. The processor unit 5 has at least one memory 6 for storing instructions and at least one processor 7 configured to execute the instructions. Based on the instructions executed by the processor 7, the following steps are performed: measuring the RF noise and / or the external magnetic field in the medical environment 2 with the corresponding sensors 3, 4; evaluating the sensor data to generate a spatial distribution of the measured RF noise and / or the measured external magnetic field in the medical environment 2; and determining a position and / or orientation of the portable MRI system 1 in the medical environment 2 for an MR imaging process based on the spatial distribution of the measured RF noise and / or the measured external magnetic field.

[0035] At least one RF noise sensor 3 and / or at least one magnetic field sensor 4 may be distributed within the medical environment 2, for example, at key locations where RF noise and / or external magnetic fields may be expected.

[0036] The portable MRI system 1 operates at a low magnetic field B (typically less than 0.3 T) and includes a conventional electromagnetic B coil, which generates this field only during actual imaging. In this embodiment, the B coil of the portable MRI system 1 is configured to be used as a magnetic field sensor 4. This is done by measuring the voltage induced in the B coil due to movement of the system 1 in an external magnetic field gradient or the time variation of the external magnetic field itself. As soon as the system is stopped, it becomes insensitive to a time-constant external magnetic field, but this is not a major drawback because a time-constant external magnetic field is typically corrected by shimming at the beginning of each MR scan and therefore does not cause significant image artifacts. Similar to MR-RF coils, the B coil has spatial and frequency-dependent magnetic field sensing properties that are also relevant for MR imaging.

[0037] In this embodiment, the MR B0 coil and magnetic field sensor in the portable MRI system 1, as well as additional external sensors 3 and 4 at fixed locations in the hospital, are used to measure the external magnetic field. To estimate the magnitude of the magnetic field, the velocity vector of the system's motion is used because the voltage induced in the B0 coil is linearly dependent on this velocity. Therefore, in one embodiment of the present invention, the system has at least one sensor for measuring the motion and / or position of the portable MRI system. The velocity can be determined based on any known method for measuring motion (GPS, triangulation, IMU, etc.), or the velocity can be obtained from data from the at least one sensor for measuring motion and / or position. This has the advantage that RF noise and magnetic fields can be related to the current position of the system and thus mapped in space. Furthermore, since a static external magnetic field can only be sensed by being induced by the system's motion, the velocity of the system is required when using the B0 coil as a sensor for the external magnetic field. As mentioned above, to estimate the magnitude of the external magnetic field, the velocity vector of the system's motion is used because the voltage induced in the B0 coil is linearly dependent on this velocity.

[0038] Additionally, dedicated RF coils may be permanently installed as RF-based communication devices, for example at hospital locations where the portable MRI system 1 is frequently used, or at or near devices known to emit transient but not easily predictable RF noise. These external noise receivers can transmit their measurements wirelessly to the portable MRI system 1 or to a central server to which the portable MRI system is also live-connected. For evaluation of the sensor data, the system has a processor unit 5 having a processor 6 and a memory 7 for executing commands.

[0039] In another embodiment of the present invention, the system includes a mapping unit. For example, RF noise and external magnetic fields at the current location of the main system 1 and the location of the external receiver, or previously mapped data of that type, are used as input data. Potentially, building layout data can be used as input data for generating a map of the medical environment. The output is an "interference map" with known and estimated interference strengths based on the measured RF noise and external magnetic fields. Here, the RF data and magnetic field data can be combined by any suitable function to provide a composite interference index. The function can include a model that estimates the level of image artifacts caused by interference for any planned or clinically relevant sequence for the current patient. All input data collected at a particular location over time can be weighted based on how frequently and how strongly interference was measured at that location in the past. This can also use a weighting factor that depends on the elapsed time since the measurement, so as to give more weight to recent measurements than to older measurements. The mapping unit can be, for example, part of the processor unit 5.

[0040] In one embodiment of the present invention, as described above, actual noise measurements during the scan are taken to augment the map data. Awareness training for changing conditions, especially in dynamically changing environments, can also be derived from the differential analysis and the results can be displayed to the user.

[0041] In other embodiments of the present invention, RF noise and / or magnetic field measurements can also be performed by handheld or wearable sensor devices 3, 4 suitable for mapping purposes, carried by staff or by autonomous, self-driving vehicles patrolling the building, for example, at night. These devices 3, 4 transmit their data to the main system's mapping unit, for example, wirelessly using the hospital wireless network, by a dedicated network, or, in the case of handheld "sniffer coils," by a simple direct cable connection to the MR receiver. The devices 3, 4 can identify operating locations that were previously identified as unsuitable and should be avoided if possible. There is no guarantee that a new noise or magnetic field source has been introduced near an area with previously low noise. Therefore, in all preferred embodiments, actual noise measurements during scanning should always be performed as described above. In this context, handheld or wearable sensor devices 3, 4 can be used to accurately identify noise sources near the portable MRI system 1.

[0042] In another embodiment of the present invention, the system comprises an artifact prediction unit configured to estimate the level of image artifacts in the MR imaging process that will be caused by the estimated interference. As inputs, RF noise and external magnetic fields at the current location and at the external receiver location, previously mapped data of the type, the current location itself, and a set of standard or planned sequences can be predicted. The artifact prediction unit can be, for example, part of the processor unit 5. As outputs, artifact scores and suggestions for MR imaging sequences and protocol parameters can be provided.

[0043] The measurement results can be used, inter alia, for live guidance. The inputs are the current locally measured interference and an interference map from data collected over time. The output is reproduced, for example, on the user interface or output unit 16, through visual, auditory, tactile, or other easily recognizable indicators, allowing staff to select an appropriate imaging position based on the cleanliness of the current local environment and the previously mapped environment. This can include a direct indication of the combined interference strength derived from the current local RF noise strength and the external magnetic field strength. Such indications can include, for example, an indication of the location of the (strong RF) emitter, as determined from a directional RF antenna, and advice to move the system in the opposite direction and / or information to help the user decide whether moving the emitter is a better alternative, or a combination thereof. Furthermore, a color map of the cleanliness of the local environment based on data from the interference map can be provided. Arrows can be used to indicate the direction to proceed, for example, based on the spatial gradient of the map data. Additional arrows can be used to indicate in which direction to rotate the opening / bore of the portable MRI system for an optimized position and / or orientation. Additionally, specific suggestions for nearby current or potentially "clean" imaging locations can be provided either on a map or as a written or audio output. A global "traffic light" may also be provided, indicating the predicted artifact level (image quality) of the planned scan at the current position / orientation. If the MR system itself is not currently moving but still detects an increase (or decrease) in local interference, this is most likely due to some switching on (off) or approaching (removing) of a strong disturbance source in the local environment. In such cases, an alarm is issued, allowing the user to identify the emitting device. Alarms are logged, so that identification can also be done after the fact. A dynamic interference visualization can also be displayed on the output unit, showing, for example, areas where the situation changes depending on time and other conditions.

[0044] FIG. 2 schematically illustrates the RF signal path of a portable MRI system 1 according to another embodiment of the present invention. The MR-RF coil 8 of the MRI system 1 is a highly sensitive receiving antenna. Therefore, according to one embodiment of the present invention, it is proposed to configure the MR-RF coil 8 to be used as the RF noise sensor 3, for example, during transport of the system 1. This has the advantage of detecting any RF noise that has the same spatial and frequency-dependent reception characteristics as those associated with MR imaging. In addition, at least one of the at least one RF noise sensor is a directional RF antenna 9. The directional antenna 9 can be used for RF noise measurements, for example, to determine the location of a strong RF emitter. These antennas 9 can also be coupled to the receive chain of the portable MRI system 1. FIG. 2 illustrates that MR receiving hardware for MRI and RF noise detection is used via the MR-RF receiving coil and additionally via a directional antenna.

[0045] 3 shows a flowchart of a computer-implemented method for determining an optimized position and / or orientation of a portable MRI system in a medical environment according to an embodiment of the present invention. The medical environment 2 is subject to RF noise and / or external magnetic fields. Therefore, first, in step S1, RF noise is measured in the medical environment by at least one RF noise sensor to provide sensor data, and / or the external magnetic field in the medical environment is measured by at least one external magnetic field sensor to provide further sensor data. In step S2, the sensor data is evaluated to generate spatial distributions of the measured RF noise and the measured external magnetic field. In step S3, a position and / or orientation of the portable MRI system for an MR imaging process is determined based on the spatial distributions of the measured RF noise and / or the measured external magnetic field.

[0046] In an embodiment of the present invention, the method may further comprise the steps of measuring RF noise and / or external magnetic fields by sensors 3, 4 distributed in the medical environment 2, and / or measuring RF noise by an MR-RF coil 8 of the portable MRI system 1, and / or measuring RF noise by a directional RF antenna 9, and / or measuring external magnetic fields by a B0 coil of the portable MRI system 1.

[0047] In another embodiment of the present invention, the method can include the further step of generating an interference map with known and estimated interference strengths based on the measured RF noise and external magnetic fields. A dynamic interference visualization can also be displayed at the output, e.g., to show areas where the situation changes with time or other conditions. Potentially, building layout data can be used as input data to generate a map of the medical environment. The output is an "interference map" with known and estimated interference strengths. Here, the RF and magnetic data can be combined by any suitable function to produce a composite interference measurement.

[0048] In another embodiment, the level of image artifacts in the MR imaging process caused by the estimated and known interference is estimated.

[0049] Based on the evaluation of the measurement results, the method can include the additional step of providing the portable MRI system operator with live guidance for positioning and / or orienting the portable MRI system 1 based on the sensor data. The current locally measured interference and interference map from data collected over time can be used as input. The output is reproduced, for example, by visual, audible, tactile, or other easily recognizable indications on the user interface or output unit 16, allowing staff to select an appropriate imaging position based on the cleanliness of the current local environment and the previously mapped environment. This can include a direct indication of the combined interference strength derived from the current local RF noise strength and external magnetic field strength. An indication of the location of (strong RF) emitters, as determined from a directional RF antenna, and advice to move the system in the opposite direction and / or information for the user to determine whether moving the emitters is a better alternative, or a combination thereof, can be provided.

[0050] In another exemplary embodiment of the invention, a computer program or a computer program element is provided which is adapted, when executed by at least one processing unit, to cause the processing unit to perform the steps of the method described above.

[0051] According to a further exemplary embodiment of the present invention, a computer readable medium, such as a CD-ROM, is presented, the computer readable medium having stored thereon a computer program element, the computer program element being as described by the preceding sections.

[0052] The computer program may be stored / distributed on a suitable medium, such as an optical storage medium or a solid-state medium, supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunications systems.

[0053] While the invention has been illustrated and described in detail in the drawings and the foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims are not to be construed as limiting the scope. Moreover, for the sake of clarity, not all elements in the drawings have been labeled with reference signs. [Explanation of symbols]

[0054] Portable Magnetic Resonance Imaging (MRI) System 1 Medical Environment 2 RF Noise Sensor 3 Magnetic Field Sensor 4 Processor Unit 5 Memory 6 Processor 7 MR-RF coil 8 RF Directional Antenna 9 Switch 10 Preamplifier 11 ADC 12 MRI Reconstruction Unit 13 MRI output unit 14 Guidance Reconstruction Unit 15 Guidance Output Unit 16 Output Unit 17

Claims

1. 1. A system for determining an optimized position and / or orientation of a portable magnetic resonance imaging (MRI) system for an MR imaging process in a medical environment subject to RF noise and / or external magnetic fields, comprising: at least one RF noise sensor configured to measure RF noise in the medical environment and provide sensor data; at least one magnetic field sensor configured to measure an external magnetic field in the medical environment and provide sensor data; a processor unit, the sensor being connected to the processor unit, the processor unit comprising: at least one memory for storing instructions; at least one processor; and wherein the processor executes the instructions to: measuring RF noise and / or external magnetic fields in the medical environment by corresponding sensors; evaluating the sensor data to generate a spatial distribution of the measured RF noise and / or the measured external magnetic field within the medical environment; determining a position and / or orientation of the portable MRI system within the medical environment for an MR imaging process based on the spatial distribution of the measured RF noise and / or the measured external magnetic field; a processor unit configured to execute A system having:

2. The system of claim 1 , wherein the at least one RF noise sensor and / or the at least one magnetic field sensor are distributed within the medical environment.

3. 3. The system of claim 1, wherein the at least one RF noise sensor and / or the at least one magnetic field sensor are portable sensor devices, and the portable sensor devices are connected to the portable MRI system wirelessly or by cable.

4. 4. The system of claim 1, wherein the at least one RF noise sensor and / or the at least one magnetic field sensor are handheld or wearable sensor devices suitable for being carried by staff and / or suitable for being carried by an autonomous self-driving vehicle.

5. The system according to any one of claims 1 to 4, wherein the MR-RF coil of the portable MRI system is configured to be used as an RF noise sensor for measuring RF noise.

6. The system of any one of claims 1 to 5, wherein at least one of the at least one RF noise sensor is a directional RF antenna for RF noise measurement.

7. The system of claim 6 , wherein the directional RF antenna is configured to be read by an MR receive chain of the portable MRI system.

8. The system of any one of claims 1 to 7, wherein a B0 coil of the portable MRI system is configured to be used as a magnetic field sensor for measuring the external magnetic field.

9. The system according to any one of claims 1 to 8, wherein the system comprises at least one sensor for measuring the movement and / or position of the portable MRI system.

10. 10. The system of claim 1, further comprising a mapping unit configured to generate an interference map with known and estimated interference intensities based on the measured RF noise and external magnetic fields.

11. 11. The system of claim 10, wherein the system comprises an MR artifact prediction unit configured to estimate a level of image artifacts in an MR imaging process that will be caused by the estimated interference.

12. 1. A computer-implemented method for determining an optimal position and / or orientation of a portable magnetic resonance imaging (MRI) system for an MR imaging process in a medical environment subject to RF noise and / or external magnetic fields, comprising: measuring RF noise in the medical environment with at least one RF noise sensor to provide sensor data, and measuring an external magnetic field in the medical environment with at least one magnetic field sensor to provide sensor data; evaluating the sensor data to generate a spatial distribution of the measured RF noise and the measured external magnetic field; determining a position and / or orientation of the portable MRI system for an MR imaging process based on the spatial distribution of the measured RF noise and / or the measured external magnetic field; A method having the following.

13. The measuring step measuring RF noise and / or external magnetic fields with sensors distributed within the medical environment, and / or measuring RF noise with an MR-RF coil of the portable MRI system, and / or measuring RF noise with a directional RF antenna, and / or measuring external magnetic fields with a B0 coil of the portable MRI system; 13. The method of claim 12, comprising:

14. 14. The method of claim 12 or 13, further comprising generating an interference map with known and estimated interference strengths based on the measured RF noise and external magnetic fields.

15. 15. The method of claim 14, further comprising estimating a level of image artifacts in an MR imaging process caused by the estimated and known interference.

16. The method of any one of claims 12 to 15, further comprising providing live guidance to an operator of the portable MRI system for positioning and / or orienting the portable MRI system based on the sensor data.

Images