System for detecting RF-induced heating in a patient undergoing an MRI examination

Abstract

The present invention relates to a system for detecting radio frequency (RF) induction heating of a patient undergoing a magnetic resonance imaging (MRI) examination. The system includes a foam and a processing unit. The foam is configured to be placed around at least a portion of a patient undergoing a magnetic resonance imaging (MRI) examination in an MRI scanner. The foam has a material, and the foam is configured so that when the foam is placed around at least a portion of the patient undergoing the MRI examination, the material is in thermal contact with the patient. The processing unit is configured to receive interrogation data of the material. The processing unit is configured to determine that RF induction heating of the patient has occurred. This determination includes utilizing the interrogation data.

Description

[Technical Field]

[0001] The present invention relates to a system for detecting radio frequency (RF) induced heating in a patient undergoing a magnetic resonance imaging (MRI) examination, a wearable patient suit or wearable item having a surface receiving coil, a method for detecting RF induced heating in a patient undergoing an MRI examination, and computer program elements and computer readable media. [Background technology]

[0002] In MRI imaging, the trend toward higher magnetic field strengths, shorter scan times, and surface transmit coils increases the risk of local radiofrequency radiation-induced heating in patients, also known as specific absorption rate (SAR) hot spots in superficial tissues. SAR is often a limitation for faster image acquisition. To address this, SAR management has been introduced, using a large safety margin for SAR during MRI imaging / examination, SAR and temperature simulation, or B1 shimming to keep local SAR below acceptable limits. See, for example, Homann H, Graesslin I, Eggers H, Nehrke K, Vernickel P, Katscher U, Dossel O, Bornert P. Local SAR management by RF shimming (a multiple human, magnetic, resin, Mater., PhD, (2012) 25 193-204).

[0003] In a standard clinical environment, staff help minimize superficial heating of the patient due to MR images / high local SAR through proper patient positioning, cable routing, and monitoring during the scan. Staff can interpret the patient's response as a complaint of elevated heating, thus indicating that the patient's RF heating or SAR is occurring. However, a sedated, impaired, or uninformed patient may not feel or report elevated heating, which can cause minor burns or even long-term skin damage. This situation is exacerbated with the move toward complete autonomy, where staff may not be present to interact with the patient to establish that RF heating / SAR is occurring.

[0004] As mentioned above, SAR often represents a limiting factor for more rapid testing. Various approaches have been explored to address this problem, but they all have major limitations.

[0005] MRI Temperature Mapping MRI temperature mapping is not suitable for monitoring surface RF heating for some purposes. Most importantly, MRI temperature mapping can only measure temperature differences, and this difference measurement is susceptible to errors caused by even small amounts of spontaneous and physiological movement (easily on the order of 5-10 degrees for small movements). After gross movement (e.g., a small arm movement), there is no way to obtain a new baseline temperature via MRI, making the MRI temperature map alone insufficient for monitoring. Second, repeated MRI temperature mapping significantly increases examination time.

[0006] US patent application US2018 / 0117186 relates to the use of doped ferrite particles as temperature sensors for non-invasive MR-based thermometry.

[0007] SAR Simulation Simulations of SAR and local heating are computationally intensive and require additional scans to provide a patient-specific model (including anatomy, electrical properties, and thermal properties). Furthermore, simulations are associated with large errors.

[0008] Use a large safety margin The SAR limits for clinical scans themselves include a safety margin due to imperfections in SAR monitoring, and SAR models for MR systems also include a safety margin for the same reason. Such margins limit examination times beyond those actually required. Better knowledge of the actual temperatures during the scan may allow those margins to be lowered.

[0009] B1 Shimming Multi-element system body coils and surface transmit coils have been proposed with the aim of increasing the flexibility of SAR management via B1 shimming, but such coils also tend to induce surface SAR that is not easy to predict from simulation to simulation. Summary of the Invention [Problem to be solved by the invention]

[0010] These issues need to be addressed.

[0011] It would be advantageous to have an improved means of detecting RF-induced heating or SAR in a patient undergoing an MRI examination. [Means for solving the problem]

[0012] The object of the present invention is solved by the subject matter of the independent claims, further embodiments are incorporated in the dependent claims. It is noted that the below described aspects and examples of the present invention also apply to a system for the detection of RF induction heating in a patient undergoing an MRI examination, a wearable patient suit or wearable item with a surface receiving coil, a method for the detection of RF induction heating in a patient undergoing an MRI examination, as well as a computer program element and a computer readable medium.

[0013] In a first aspect, there is provided a system for detecting radio frequency (RF) induced heating in a patient undergoing a magnetic resonance imaging (MRI) examination, the system comprising: a form; and a processing unit.

[0014] The foam is configured to be placed around at least a portion of a patient undergoing a magnetic resonance imaging (MRI) examination in an MRI scanner. The form includes a material. The foam is configured such that when the foam is placed around at least a portion of the patient undergoing the MRI examination, the material is in thermal contact with the patient. A processing unit is configured to receive interrogation data of the material. The processing unit is configured to determine that RF induction heating of the patient has occurred. This determination includes utilizing the interrogation data.

[0015] In this way, the risk of local RF heating of the patient can be minimized.

[0016] In one example, at least one property of the material changes with temperature, and the interrogation data can include MRI data of the material.

[0017] In one example, the material is configured to undergo a temperature-dependent phase transition, the processing unit is configured to analyze the MRI data of the material to determine that the material has undergone a temperature-dependent phase transition, and the processing unit is configured to determine that RF inductive heating of the patient has occurred based on the determination that the material has undergone a temperature-dependent phase transition.

[0018] In one example, the processing unit is configured to analyze the MRI data of the material to determine where the material has undergone a temperature-dependent phase transition.

[0019] In one example, the material is configured to undergo a temperature-dependent phase transition at a phase transition temperature.

[0020] In one example, the material is configured to undergo a temperature-dependent phase transition due to RF induction heating of the patient caused by an MRI scanner during an MRI examination of the patient.

[0021] In one example, the material is configured to undergo a sol-gel transition.

[0022] In one example, the material includes chitosan.

[0023] In one example, the material comprises poly(N-isopropylacrylamide).

[0024] In one example, the material includes chitosan and poly(N-isopropylacrylamide).

[0025] In one example, the system may include at least one temperature sensor embedded in the material, and the interrogation data may include temperature sensor data from the at least one temperature sensor.

[0026] In one example, the at least one sensor comprises one or more fiber optic temperature sensors.

[0027] In one example, based on a determination that RF induced heating of the patient has occurred, the processing unit is configured to output information that can be used to do one or more of the following: change the scan sequence of the MRI scanner to a sequence that delivers a reduced specific absorption rate; stop the scan; or alert staff.

[0028] In one example, this form is a wearable patient suit or a wearable item having a surface receiving coil.

[0029] In a second aspect, a wearable patient suit or wearable article is provided having a surface receive coil. The wearable patient suit or wearable item having a surface receive coil is configured to be placed around at least a portion of a patient undergoing a magnetic resonance imaging (MRI) examination in an MRI scanner. The wearable patient suit or wearable item having a surface receive coil includes a material. The wearable patient garment or wearable item having a surface receive coil is configured such that the material is in thermal contact with the patient when the wearable patient garment or wearable item having a surface receive coil is placed around at least a portion of the patient undergoing the MRI examination. Interrogation data of the material can be used to determine whether RF inductive heating of the patient has occurred.

[0030] In a third aspect, there is provided a method for detecting radio frequency (RF) induced heating of a patient undergoing a magnetic resonance imaging (MRI) examination, the method comprising the steps of: a) placing a foam in an MRI scanner around at least a portion of the patient undergoing a magnetic resonance imaging (MRI) examination, the foam comprising a material configured such that when the foam is placed around at least a portion of the patient undergoing the MRI examination, the foam is in thermal contact with the patient; b) receiving, by a processing unit, interrogation data of the material; and c) determining, by the processing unit, that RF induced heating of the patient has occurred, the determining step utilizing the interrogation data.

[0031] According to another aspect, there is provided a computer program element for controlling one or more of the aforementioned systems, the computer program element being adapted to perform the aforementioned methods when executed by a processing unit.

[0032] According to another aspect, there is provided a computer readable medium having stored thereon a computer element as described above.

[0033] The computer program element may for example be a software program, but also an FPGA, a PLD or any other suitable digital means.

[0034] Advantageously, any advantages provided by any of the above aspects apply equally to all of the other aspects, and vice versa.

[0035] These aspects and examples will be apparent from and elucidated with reference to the embodiments described hereinafter.

[0036] Exemplary embodiments are described below with reference to the following drawings: [Brief explanation of the drawings]

[0037] [Figure 1] 1 illustrates a schematic diagram of an example system for detecting radio frequency induced heating in a patient undergoing magnetic resonance imaging. [Figure 2] 1 illustrates a method for detecting radio frequency induced heating in a patient undergoing a magnetic resonance imaging examination. [Figure 3] FIG. 3 shows a schematic example of diagnostic MRI data used as interrogation data for a phase change material in a wearable suit or in a suit with surface receive coils around the patient. DETAILED DESCRIPTION OF THE INVENTION

[0038] FIG. 1 shows a schematic example of a system 10 for detecting radio frequency (RF) induced heating of a patient undergoing a magnetic resonance imaging (MRI) examination. The system 10 comprises a form 20 and a processing unit 30. The form is configured to be placed around at least a portion of a patient undergoing a magnetic resonance imaging (MRI) examination in an MRI scanner. The form includes a material 40, and the form is configured such that when the form is placed around at least a portion of the patient undergoing the MRI examination, the material is in thermal contact with the patient. The processing unit is configured to receive interrogation data of the material. The processing unit is configured to determine that RF induced heating of the patient has occurred. The determination by the processing unit includes utilizing the interrogation data.

[0039] According to one example, at least one property of the material changes with temperature, and the interrogation data can include MRI data of the material.

[0040] According to one example, the material is configured to undergo a temperature-dependent phase transition, the processing unit is configured to analyze the MRI data of the material to determine that the material has undergone a temperature-dependent phase transition, and the processing unit is configured to determine that RF inductive heating of the patient has occurred based on the determination that the material has undergone a temperature-dependent phase transition.

[0041] According to one example, the processing unit is configured to analyze the MRI data of the material to determine where the material has undergone a temperature-dependent phase transition.

[0042] According to one example, the material is configured to undergo a temperature dependent phase transition at a phase transition temperature.

[0043] In one example, the phase transition temperature is in the range of 40°C to 60°C.

[0044] In one example, the phase transition temperature is in the range of 45°C to 60°C.

[0045] In one example, the phase transition temperature is in the range of 40°C to 50°C.

[0046] According to one example, the material is configured to undergo a temperature dependent phase transition due to RF inductive heating of the patient caused by an MRI scanner during an MRI examination of the patient.

[0047] According to one example, the material is configured to undergo a sol-gel transition.

[0048] According to one example, the material includes chitosan. Alternatively or additionally, the material comprises poly(N-isopropylacrylamide).

[0049] According to one example, the system comprises at least one temperature sensor 50 integrated into the material. The interrogation data can then include temperature sensor data from the at least one temperature sensor.

[0050] According to one example, the at least one sensor comprises one or more fiber optic temperature sensors.

[0051] According to one example, based on a determination that RF induced heating of the patient has occurred, the processing unit is configured to output information usable to perform one or more of the following steps: change the scan sequence of the MRI scanner to a sequence that delivers a reduced specific absorption rate; stop the scan; and alert staff.

[0052] According to one example, this form is a wearable patient suit or a wearable item having a surface receiving coil.

[0053] From the above description of the system, it is clear that Figure 1 also relates to a wearable patient suit 20 or wearable item having a surface receive coil 20. The wearable patient suit or wearable item having a surface receive coil is configured to be placed around at least a portion of a patient undergoing a magnetic resonance imaging (MRI) examination in an MRI scanner. The wearable patient suit or wearable item having a surface receive coil includes a material 40. The wearable patient suit or wearable item having a surface receive coil is configured such that the material is in thermal contact with the patient when the wearable patient suit or wearable item having a surface receive coil is placed around at least a portion of the patient undergoing the MRI examination. Interrogation data of the material can be used to determine that RF inductive heating of the patient has occurred.

[0054] In one example, at least one property of the material varies with temperature, and the material is configured such that MRI data of the material is usable as interrogation data.

[0055] In one example, the material is configured to undergo a temperature dependent phase transition.

[0056] In one example, the material is configured to undergo a temperature-dependent phase transition at a phase transition temperature.

[0057] In one example, the phase transition temperature is in the range of 40°C to 60°C.

[0058] In one example, the phase transition temperature is in the range of 45°C to 60°C.

[0059] In one example, the phase transition temperature is in the range of 40°C to 50°C.

[0060] In one example, the material is configured to undergo a temperature-dependent phase transition due to RF induction heating of the patient caused by an MRI scanner during an MRI examination of the patient.

[0061] In one example, the material is configured to undergo a sol-gel transition.

[0062] In one example, the material includes chitosan.

[0063] In one example, the material comprises poly(N-isopropylacrylamide).

[0064] In one example, at least one temperature sensor 50 is incorporated into the material. Temperature sensor data from at least one temperature sensor can be used as query data.

[0065] In one example, the at least one sensor comprises one or more fiber optic temperature sensors.

[0066] 2 illustrates an example of a method 100 for detecting radio frequency (RF) induced heating in a patient undergoing a magnetic resonance imaging (MRI) examination in its basic steps. In a positioning step 110, also referred to as step a), positioning a foam around at least a portion of a patient undergoing a magnetic resonance imaging (MRI) examination in an MRI scanner, the foam comprising a material configured to be in thermal contact with the patient when the foam is positioned around at least a portion of the patient undergoing the MRI examination; receiving material query data by a processing unit in a receiving step 120, also referred to as step b); determining, by the processing unit, in a determining step 130, also referred to as step c), that RF induction heating of the patient has occurred, the determining step including utilizing interrogation data; It has.

[0067] In one example, at least one property of the material changes with temperature, and the interrogation data can include MRI data of the material.

[0068] In one example, the material is configured to undergo a temperature-dependent phase transition. The method then includes analyzing, with a processing unit, MRI data of the material to determine that the material has undergone a temperature-dependent phase transition. In step c), determining that RF inductive heating of the patient has occurred is based on determining that the material has undergone a temperature-dependent phase transition.

[0069] In one example, step c) includes analyzing the MRI data of the material by a processing unit to determine where the material has undergone a temperature-dependent phase transition.

[0070] In one example, the material is configured to undergo a temperature-dependent phase transition at a phase transition temperature.

[0071] In one example, the phase transition temperature is in the range of 40°C to 60°C.

[0072] In one example, the phase transition temperature is in the range of 45°C to 60°C.

[0073] In one example, the phase transition temperature is in the range of 40°C to 50°C.

[0074] In one example, the material is configured to undergo a temperature-dependent phase transition due to RF induction heating of the patient caused by an MRI scanner during an MRI examination of the patient.

[0075] In one example, the material is configured to undergo a sol-gel transition.

[0076] In one example, the material includes chitosan.

[0077] In one example, the material comprises poly(N-isopropylacrylamide).

[0078] In one example, at least one temperature sensor is embedded in the material, and the interrogation data can include temperature sensor data from the at least one temperature sensor.

[0079] In one example, the at least one sensor comprises one or more fiber optic temperature sensors.

[0080] In one example, based on a determination that RF induced heating of the patient has occurred, the method includes outputting processing unit information usable to perform one or more of the following steps: changing the scan sequence of the MRI scanner to a sequence that delivers a reduced specific absorption rate; stopping the scan; and alerting staff.

[0081] In one example, this form is a wearable patient suit or a wearable item having a surface receiving coil.

[0082] A system for detecting RF induced heating in a patient undergoing an MRI examination, a wearable patient suit or wearable item having a surface receiving coil, and a method for detecting RF induced heating in a patient undergoing an MRI examination will now be described in further detail with respect to a specific embodiment with reference to FIG. 3 .

[0083] Standard MRI surface coils are relatively bulky and therefore uncomfortable for the patient. They are also not flexible enough to conform to the patient's shape. However, in recent years, highly flexible, stretchable weighted receive coils have been developed that conform perfectly to the patient's skin. For example, https: / / www.gehealthcare.com / products / magnetic resonance imaging / air technology; https: / / www.auntminnie.com / index.aspx?sec=sup&sub=mri&pag=dis&ItemID=125579; Also see "Liquid Metal in Elastic Tubes: A Wearable Four-Channel Knee Array" by Andreas Port, Loris Albisetti, Matija Varga, Josip Marjanovic, Jonas Reber, David Brunner, and Klaas Pruessmann (Proceedings ISMRM 2019 #1114).

[0084] The inventors recognized that such a patient suit, integrating a wearable coil and covering most of the patient, could be utilized in a new way. The new technology was that the risk of local RF heating in an autonomous setting could be minimized by surface temperature measurements performed by the MRI system itself. This is achieved by incorporating a temperature-sensitive material into such a wearable, lightweight surface receiver coil. The material used changes MRI signal levels with temperature due to a phase transition in which the material is in thermal contact with the patient and temperature changes in the material are due to changes in the patient's temperature. Patient suits that cover the patient and do not have a surface receiver coil but only have temperature-sensitive material can also be utilized. This approach avoids the difficulties of MRI temperature mapping and works without any additional system components, except for the wearable coil or a layer of material within the patient suit. This approach provides an effective way to determine whether RF heating (or SAR) of the patient has occurred and does so in a manner that provides patient comfort.

[0085] Even a wearable coil or patient suit with such a coil, including a temperature-sensitive material, would, in principle, provide the opportunity to measure surface temperature globally over a large area. This allows for efficient and effective monitoring of RF heating, since the location where heating will occur is not easy to predict. To make the system for large-area body temperature monitoring compatible with MRI, the first of the following two embodiments achieves this by using the MRI scanner itself for temperature measurement. This also has a cost advantage, since no specific temperature sensor is required.

[0086] In this embodiment, the wearable coil is utilized with a phase-change material. Many materials undergo phase transitions induced by temperature changes, and in many cases, the phase transition significantly alters MRI signal characteristics (T1 and T2 relaxation times). Therefore, the wearable MRI coil / patient suit includes an inner layer of such material to provide close thermal contact when worn by a patient undergoing an MRI scan, separated from the patient's skin only by a thin layer of clothing. The material is selected to change its MR properties, e.g., to have phase transitions between 40°C and 60°C, 45°C and 60°C, and 40°C and 50°C. Materials can be configured to have different temperature ranges over which the phase transition occurs, as needed. MRI images are used to monitor the phase state of the material. This can be done using an MRI scan that is part of the diagnostic examination or by an extra scan interleaved with the diagnostic scan. Diagnostic 3D scans are appropriate because they already include a large area of ​​the patient's skin.

[0087] Figure 3 shows an example of a patient wearing a wearable MRI coil / patient suit with an inner layer of phase-change material. The wearable MRI coil / patient suit is not actually shown. When a patient undergoes an MRI scan, the phase-change material is in thermal contact with the patient's exterior, e.g., the skin. Therefore, when a portion of the patient begins to heat up due to SAR, the phase-change material in contact with that portion of the patient also heats up, and if the temperature rise is large enough, the material undergoes a phase change, which can be detected from the MRI data.

[0088] While the wearable MRI coil / patient suit is not actually shown in Figure 3 above, an extra scan consisting of several stacks of 1 to 3 slices covering the surface of the patient where the wearable MRI coil / patient suit is located is shown in the area of ​​the wearable MRI coil / patient suit. Thus, there are fewer monitoring stacks, each with a slice, covering the circumference of the patient. Each stack can be automatically positioned based on the coil sensitivity scan and survey scan performed at the beginning of each MRI exam. The scan time for these extra scans is not prohibitive for several reasons: the signal-to-noise ratio (SNR) is high because they are located adjacent to the receive coil elements, and fewer than 20 slices are required to cover a large area of ​​the patient.

[0089] The scan is repeated at regular intervals and any significant signal change indicative of RF heating is used to trigger predefined actions, as defined below.

[0090] An ideal phase change material would be 1HMR signal supply, Phase transition at a desired temperature, The significant changes in MRI relaxation times due to phase transitions, Flexibility in both relevant phases, and Material 7 permitted in MRI environments The characteristics of

[0091] Materials that undergo a sol-gel transition are found to be suitable for this purpose. A good example is the use of thermogelling aqueous chitosan solutions. Chitosan is an aminopolysaccharide that can be obtained from chitin, a cellulose-like polymer present in the exoskeleton of insects, for example. Chitosan is biodegradable and has become increasingly important in biomedical applications and the food industry (see Chenite R, et al. Rheological characterisation of thermogelling chitosan / glycerol-phosphate solutions (Carbohydrate Polymers (2001) 46 39-47)).

[0092] Chitosan / glycerol-phosphate aqueous solutions exhibit a sol-gel transition in the appropriate temperature range of approximately 40-50°C, and the temperature of the sol-gel transition can be adjusted by selecting a pH value in the biocompatible range around pH 7. The T2 relaxation time of the solution changes from approximately 2.5 s to 1.2 s during this phase transition (see Kock FVC and Colnago LA, "Rapid Monitoring of Chitosan Solidification Using Low-Field NMR Relaxometry," Carbohydrate Polymers (2016) 50 1-4)). This results in a significant change in the MR signal for turbo spin echo (TSE) MR imaging.

[0093] A second suitable material system is poly(N-isopropylacrylamide) (PNIPAM) in aqueous solution, which undergoes a sol-gel phase transition at approximately 32°C (Matsukawa S et al. Structural and Dynamic Behavior of Polymer Gels Revealed by Nuclear Magnetic Resonance Spectroscopy (In: Polymer Gels and Networks, 2001, CRC Press, p234. ISBN13: 9780824706692)). However, by selecting the weight concentration, the transition temperature can be adjusted by copolymerization with appropriate monomers and additives (Cao Y et al. Poly(N-isopropylacrylamide) chitosan as a thermosensitive in situ gel-forming system for ocular drug delivery (J of controlled release (2007) 120(3) 186-194, https: / / www.sigmaaldrich.com / materials science / polymer science / nipampolymers.html). Note that this material is biodegradable and has been used for drug delivery in humans.

[0094] Rather than using a phase change material, the material of the wearable MRI coil / patient suit, which is in thermal contact with the patient undergoing the MRI scan, has a fiber optic distributed temperature sensor (see https: / / www.nktphotonics.com / lios / en / technology / distributedtemperaturesensing / ), as it is MRI safe, i.e., it works without any interaction with the MRI system, and provides a temperature profile along a fiber several meters long with a time resolution of 1 Hz or better.

[0095] The fiber, which can be several meters long, is embedded in a serpentine loop within the material of the wearable MR surface coil. If a temperature rise along the fiber is detected, the known serpentine shape of the fiber can be used to determine the location of hot spots on the patient.

[0096] The body temperature data in the above embodiment is Change of sequence to a mode with less SAR (W / Kg) Scan stop when heating, and Reminding staff to take appropriate action It is used to automatically trigger actions such as

[0097] In another exemplary embodiment, a computer program or computer program element is provided, characterized in that it is configured to execute the method steps of the method according to one of the aforementioned embodiments on a suitable device or system. Thus, the computer program element may be stored on a computing unit that may be part of the embodiment. This computing unit may be configured to execute or trigger the execution of the steps of the above-described method. Furthermore, it may be configured to operate the components of the above-described device and / or system. The computing unit may be configured to operate automatically and / or to execute user commands. The computer program may be loaded into the working memory of a data processor. Thus, the data processor may be equipped to execute the method according to one of the aforementioned embodiments.

[0098] This exemplary embodiment of the present invention encompasses both computer programs that use the present invention from the beginning, and computer programs that convert existing programs into programs that use the present invention by means of an update.

[0099] Furthermore, the computer program element may provide all the steps necessary to fulfill the steps of the exemplary embodiments of the procedures described above.

[0100] According to a further exemplary embodiment of the present invention, a computer readable medium such as a CDROM, USB stick, etc. is presented, the computer readable medium having stored thereon a computer program element, which computer program element is described by the previous section.

[0101] The computer program may be stored and / or 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 communication systems.

[0102] However, the computer program may also be presented via a network such as the World Wide Web and downloaded into the working memory of a data processor from such a network. According to a further exemplary embodiment of the invention, a medium for making a computer program element available for downloading is provided, the computer program element being configured to perform a method according to one of the aforementioned embodiments of the invention.

[0103] It should be noted that embodiments of the present invention are described with reference to different subject matters. In particular, some embodiments are described with reference to method-type claims, and other embodiments are described with reference to apparatus-type claims. However, those skilled in the art will gather from the above and following description that, unless otherwise indicated, any combination of features belonging to one type of subject matter, as well as any combination between features relating to different subject matters, are considered to be disclosed in this application. However, all features can be combined to provide synergistic effects that are greater than the simple sum of the features.

[0104] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered exemplary 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 dependent claims.

[0105] 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. A single processor or other unit may fulfill the functions of several items recited in the claims. 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 should not be interpreted as limiting the scope.

Claims

1. 1. A system for detection of radio frequency (RF) induced heating in a patient undergoing a magnetic resonance imaging (MRI) examination, the system comprising: Form and Processing unit and the foam being configured to be placed around at least a portion of a patient undergoing a magnetic resonance imaging examination in a magnetic resonance imaging scanner; the foam has a material configured such that when the foam is positioned around at least a portion of the patient undergoing the magnetic resonance imaging examination, the material is in thermal contact with the patient; the processing unit is configured to receive the material query data; the processing unit is configured to determine that RF induction heating of the patient has occurred, the determination comprising utilization of the interrogation data, wherein at least one property of the material varies with temperature, the interrogation data comprising magnetic resonance imaging data of the material, the material being configured to undergo a temperature-dependent phase transition, the processing unit is configured to analyze the magnetic resonance imaging data of the material to determine that the material has undergone the temperature-dependent phase transition, and the processing unit is configured to determine that RF induction heating of the patient has occurred based on the determination that the material has undergone the temperature-dependent phase transition. system.

2. The system of claim 1 , wherein the processing unit is configured to analyze the magnetic resonance imaging data of the material to determine where in the foam the material underwent the temperature-dependent phase transition.

3. 3. The system of claim 1, wherein the material is configured to undergo the temperature-dependent phase transition at a phase transition temperature.

4. 4. The system of claim 2, wherein the material is configured to undergo the temperature-dependent phase transition due to RF induction heating of the patient provided by the magnetic resonance imaging scanner during a magnetic resonance imaging examination of the patient.

5. The system of claim 1 , wherein the temperature-dependent phase transition is a sol-gel transition.

6. 6. The system of claim 1, wherein the material comprises chitosan and / or the material comprises poly(N-isopropylacrylamide).

7. 7. The system of claim 1, wherein the system comprises at least one temperature sensor incorporated into the material, and the interrogation data comprises temperature sensor data from the at least one temperature sensor.

8. 8. The system of claim 7, wherein the at least one temperature sensor comprises one or more fiber optic temperature sensors.

9. 9. The system of claim 1, wherein, based on a determination that RF induction heating of the patient has occurred, the processing unit is configured to output information usable to perform one or more of the following steps: change the scan sequence of the magnetic resonance imaging scanner to a sequence that delivers a reduced specific absorption rate; stop the scan; or alert staff.

10. 10. The system of any one of claims 1 to 9, wherein the form is a wearable item or a wearable patient suit having a surface receiving coil.

11. 1. A wearable item or wearable patient suit comprising a surface receive coil, the wearable item or wearable patient suit comprising the surface receive coil configured to be placed around at least a portion of a patient undergoing a magnetic resonance imaging examination in a magnetic resonance imaging scanner, the wearable item or wearable patient suit comprising the surface receive coil having a material configured such that when the wearable item or wearable patient suit comprising the surface receive coil is placed around at least a portion of the patient undergoing the magnetic resonance imaging examination, the material is in thermal contact with the patient, and interrogation data of the material in the form of magnetic resonance imaging data acquired during the magnetic resonance imaging examination is usable to determine that the material has undergone a temperature dependent phase transition, and from the determination that the temperature dependent phase transition has occurred, to determine that RF induction heating of the patient has occurred.

12. 1. A method for detection of radio frequency (RF) induced heating in a patient undergoing a magnetic resonance imaging (MRI) examination, comprising: a) placing a foam around at least a portion of a patient undergoing a magnetic resonance imaging examination in a magnetic resonance imaging scanner, the foam having a material configured such that the material is in thermal contact with the patient when the foam is placed around at least a portion of the patient undergoing the magnetic resonance imaging examination; b) receiving, by a processing unit, interrogation data comprising magnetic resonance imaging data of said material acquired during said magnetic resonance imaging examination; c) determining by the processing unit that RF inductive heating of the patient has occurred, said determining comprising utilizing the interrogation data, wherein at least one property of the material varies with temperature, and wherein the material is configured to undergo a temperature dependent phase transition; d) analyzing the magnetic resonance imaging data of the material to determine that the material has undergone the temperature-dependent phase transition; A method comprising:

13. A computer program element for controlling a system according to any one of claims 1 to 10, the computer program element being arranged to carry out the method of claim 12 when executed by a processor of said system.

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