Magnetic Resonance Imaging Method

Abstract

The present invention relates to a method for imaging a part of a human or animal body using a magnetic resonance imaging device, wherein the imaging method comprises the use of a belt that surrounds a torso section of the body, referred to as a contact section, with one of its own surfaces, referred to as a first surface, the belt being electrically conductive and set to the same potential as all electrical and electronic elements constituting the magnetic resonance imaging device during the acquisition of a magnetic resonance image of the part of the human body, thereby allowing the flow of electric charge.

Description

Technology Field

[0001] The present invention relates to the field of magnetic resonance imaging. In particular, the present invention relates to a magnetic resonance imaging method. More specifically, the magnetic resonance imaging method according to the present invention uses means for limiting the influence of ambient noise, in particular electronic noise captured by an electronic control module of a device used to form an MRI image of the body using an MRI device. Background Technology

[0002] Magnetic resonance imaging (MRI) is currently widely used to non-invasively image the body, and in particular the interior of the human body. Specifically, MRI enables the examination of the hydrogen nuclei of water molecules that form parts of the body being examined, particularly their nuclear spins.

[0003] In this regard, the MRI device is provided with a magnet configured to apply a static magnetic field (referred to as the “main magnetic field”) to the body, and as a result, nuclear spins associated with hydrogen nuclei contained in water molecules forming part of the body are polarized.

[0004] In particular, the magnetic moments associated with these spins preferentially align along an axis referred to as the z-axis, which is determined by the orientation of the main magnetic field, thereby generating magnetization of the body.

[0005] The MRI device also includes a gradient coil configured to generate a magnetic field that has a small amplitude and varies in space when current is applied. More specifically, the gradient coil is aligned parallel to the main magnetic field and is designed to generate a magnetic field component whose amplitude varies linearly depending on the position along one of the x-axis, y-axis, or z-axis (each pair of the x-axis, y-axis, and z-axis is perpendicular).

[0006] Therefore, the combined effect of the magnetic field applied by the gradient coil enables spatial encoding of each location of the body to be investigated.

[0007] The MRI device also includes at least one RF coil intended to serve as a radio frequency (RF) receiver / transmitter. In particular, at least one RF coil is configured to emit RF energy pulses of a frequency equal to or close to the resonant frequency of hydrogen nucleus spins, which are at least partially absorbed by these nuclei.

[0008] As soon as RF emission ceases, the nuclear spin relaxes to return to its initial energy state, consequently emitting an RF signal that can be collected by at least one RF coil. This RF signal is then processed using a computer and reconstruction algorithms to acquire images of the body.

[0009] Generally, a main magnetic field of 1.5 to 3 Tesla enables a relatively reasonable signal-to-noise ratio to be achieved, and consequently, allows for the formation of images of the human body of sufficient quality over a duration of approximately 1 minute or more.

[0010] However, there are situations where it is not possible to generate a main magnetic field of such strength. Portable MRI devices are an example. The latter generally contain permanent magnets or electromagnets of limited capacity and cannot apply a main magnetic field with a strength exceeding 60 mT or even 200 mT without negatively affecting the mass or volume of the MRI device under consideration.

[0011] In terms of main magnetic field strength, these limitations directly affect the performance of MRI devices. In particular, the quality of images acquired by such MRI devices can be significantly degraded by an unfavorable signal-to-noise ratio. This unfavorable signal-to-noise ratio is a result of the rapid reduction in tissue magnetization caused by the use of low-amplitude main magnetic fields.

[0012] One objective of the present invention is to provide a magnetic resonance imaging method that can reduce noise when the main magnetic field is weak, specifically when it is less than 100 mT.

[0013] Another objective of the present invention is to provide a magnetic resonance imaging method that reduces noise in low magnetic fields when the main magnetic field is weak, specifically when it is less than 100 mT, and complies with electrical safety standards, particularly IEC 60601-1.

[0014] To achieve this objective, the present invention proposes a method for imaging a part of a human or animal body using a magnetic resonance imaging device, said imaging method comprising the use of a belt that surrounds a torso section of said body (hereinafter referred to as the "contact section") through one of its surfaces (hereinafter referred to as the "first surface"), said belt being electrically conductive and set to the same potential as all electrical and electronic elements constituting the magnetic resonance imaging device during the acquisition of a magnetic resonance image of a part of the human body to allow the flow of electric charge.

[0015] In a particularly advantageous embodiment, a belt connected to ground potential may be provided. In other words, according to this embodiment, not only the belt but also all electrical and electronic elements are connected to ground potential.

[0016] According to one embodiment, the potential is the same as the ground potential.

[0017] According to one embodiment, the belt comprises a matrix made of an electrical insulating material, preferably a polyamide material.

[0018] According to one embodiment, the belt includes a metal structure on its first surface, and all metal structures have the same potential as all electrical and electronic elements constituting the magnetic resonance imaging device during the acquisition of a magnetic resonance image of a part of the human body, thereby allowing the flow of electric charge.

[0019] According to one embodiment, the metal structure comprises at least one of a metal plate such as a sheet, a metal foil such as aluminum foil, and a metal button.

[0020] According to one embodiment, metal structures are electrically connected to each other, particularly by a bundle of electrically conductive connecting wires, and preferably, the connecting wires comprise at least one of silver, copper, or tin.

[0021] According to one embodiment, the metal structure is clipped onto, bonded to, or sewn onto a matrix.

[0022] According to one embodiment, the metal structure is rectangular or square in shape and arranged in a checkerboard pattern, and preferably, the metal structure covers at least 85% of the area on the first surface intended to contact the contact section as a whole.

[0023] According to one embodiment, the belt comprises a set of contact wires arranged in a matrix, and the contact wires are connected to the same potential as all electrical and electronic elements of the magnetic resonance imaging device during the acquisition of a magnetic resonance image of a part of the human body to allow the flow of electric charge, and preferably, the contact wires comprise at least one of a material selected from silver, copper and tin.

[0024] According to one embodiment, the imaging method uses an imaging device equipped with a magnet that limits the space in which a part of the body is located during magnetic resonance imaging, and the magnet applies a magnetic field of less than 100 mT, more preferably less than 50 mT, during the acquisition.

[0025] According to one embodiment, part of the body includes a head.

[0026] According to one embodiment, the belt has a width of 18 cm to 30 cm.

[0027] According to one embodiment, the belt has a surface electrical resistance of less than 1 ohm per square, preferably less than 0.5 ohms per square, and more preferably less than 0.1 ohm per square.

[0028] The present invention also relates to a magnetic resonance imaging device equipped with a belt designed to provide electrical contact with a contact section on the torso of a body, wherein the belt is electrically conductive and connected at the same potential as all electrical and electronic elements of the magnetic resonance imaging device during the acquisition of a magnetic resonance image of a part of the human body, thereby allowing the flow of electric charge.

[0029] In one embodiment, the belt comprises a matrix made of an electrical insulating material, preferably a polyamide material.

[0030] In one embodiment, the belt includes a metal structure on its first surface, and all metal structures are at the same potential as all electrical and electronic elements constituting the magnetic resonance imaging device during the acquisition of a magnetic resonance image of a part of the human body, thereby allowing the flow of charge.

[0031] In one embodiment, the metal structure comprises at least one of a metal plate such as a sheet, a metal foil, or a metal button.

[0032] In one embodiment, the metal structures are electrically connected to each other, particularly by a bundle of electrically conductive connecting wires, and preferably, the connecting wires comprise at least one of silver, copper, or tin.

[0033] In one embodiment, the metal structure is clipped onto, bonded to, or sewn onto the matrix.

[0034] In one embodiment, the metal structure is rectangular or square in shape and arranged in a checkerboard pattern, and preferably, the metal structure covers at least 85% of the area of ​​the first surface intended to contact the contact section as a whole.

[0035] In one embodiment, the belt comprises a set of contact wires arranged in a matrix, and the contact wires are connected to the same potential as all electrical and electronic elements constituting the magnetic resonance imaging device during the acquisition of a magnetic resonance image of a part of the human body to allow the flow of electric charge, and preferably, the contact wires comprise at least one of a material selected from silver, copper and tin.

[0036] In one embodiment, the belt has a width of 18 cm to 30 cm.

[0037] In one embodiment, the belt has a surface electrical resistance of less than 1 ohm per square, preferably less than 0.5 ohms per square, and more preferably less than 0.1 ohm per square.

[0038] The present invention relates to a belt intended for use while imaging a part of a human body using a magnetic resonance imaging device, wherein the belt comprises a surface referred to as a first surface and is designed to provide electrical contact with a contact section on the torso of the body through its first surface, said belt is electrically conductive and allows the flow of electric charge when connected to the same potential as all electrical and electronic elements of the magnetic resonance imaging device during the acquisition of a magnetic resonance image of a part of the human body.

[0039] In one embodiment, the belt comprises a matrix made of an electrical insulating material, preferably a polyamide material.

[0040] In one embodiment, the belt includes a metal structure on its first surface, and all metal structures are at the same potential as all electrical and electronic elements constituting the magnetic resonance imaging device during the acquisition of a magnetic resonance image of a part of the human body, thereby allowing the flow of charge.

[0041] In one embodiment, the metal structure comprises at least one of a metal plate such as a sheet, a metal foil, or a metal button.

[0042] In one embodiment, the metal structures are electrically connected to each other, particularly by a bundle of electrically conductive connecting wires, and preferably, the connecting wires comprise at least one of silver, copper, or tin.

[0043] In one embodiment, the metal structure is clipped onto, bonded to, or sewn onto the matrix.

[0044] In one embodiment, the metal structure is rectangular or square in shape and arranged in a checkerboard pattern, and preferably, the metal structure covers at least 85% of the area of ​​the first surface intended to contact the contact section as a whole.

[0045] In one embodiment, the belt comprises a set of contact wires arranged in a matrix, and the contact wires are connected to the same potential as all electrical and electronic elements constituting the magnetic resonance imaging device during the acquisition of a magnetic resonance image of a part of the human body to allow the flow of electric charge, and preferably, the contact wires comprise at least one of a material selected from silver, copper and tin.

[0046] In one embodiment, the belt has a width of 18 cm to 30 cm.

[0047] In one embodiment, the belt has a surface electrical resistance of less than 1 ohm per square, preferably less than 0.5 ohms per square, and more preferably less than 0.1 ohm per square. Brief explanation of the drawing

[0048] Other features and advantages of the present invention will become apparent from the following specific description for carrying out the invention with reference to the attached drawings. [Fig. 1] Fig. 1 is a schematic exploded view of a magnetic resonance imaging device that can be used in the context of the present invention. [Fig. 2] Fig. 2 is a photograph of a section of a human torso with belts arranged around it according to the principle presented in the present invention. [Fig. 3] Fig. 3 is a schematic diagram of a belt that can be used in the present invention according to a first embodiment. [Fig. 4] Fig. 4 is a schematic diagram of a belt that can be used in the present invention according to a first variation of the second embodiment. [Fig. 5] Fig. 5 is a schematic diagram of a belt that can be used in the present invention according to a second variation of the second embodiment. [Fig. 6] Fig. 6 is a schematic diagram of another example of a belt that can be used in the present invention according to a second variation of the second embodiment. [Fig. 7] Fig. 7 is a schematic diagram of another example (third example) of a belt that can be used in the present invention according to a second variation of the second embodiment. [Fig. 8] Fig. 8 is a schematic diagram of another example (fourth example) of a belt that can be used in the present invention according to a second variation of the second embodiment. [Fig. 9] Fig. 9 is a schematic diagram of another example (last example) of a belt that can be used in the present invention according to a second variation of the second embodiment. Specific details for implementing the invention

[0049] The present invention relates to a method for imaging a part of a human or animal body. In particular, the imaging method uses a magnetic resonance imaging device, specifically a so-called low-field magnetic resonance imaging device. The term "low-field" refers to a main magnetic field having a strength of less than 200 mT, preferably less than 100 mT, and more preferably less than 50 mT.

[0050] Accordingly, FIG. 1 is a schematic diagram of a magnetic resonance imaging device (1) that can be used within the scope of the present invention.

[0051] The imaging device (1) includes a magnet, in particular a permanent magnet (2). The permanent magnet (2) can be extended particularly along an elongation axis (z).

[0052] More specifically, the permanent magnet (2) defines a bore (3) that is open through a first opening (4) and a second opening (5) that are opposite each other along the extension axis (z).

[0053] In this regard, the magnet (2) is arranged so that the body, more specifically the human body, can be inserted into the bore (3) through the first opening (4) along the extension axis (z).

[0054] The permanent magnet (2) is configured to apply a static magnetic field oriented along an axis perpendicular to the extension axis (z) in a region of the bore (3) referred to as the analysis zone, more specifically.

[0055] In this regard, the permanent magnet (2) may be arranged in an assembly of basic magnets, in particular in a series of Halbach rings. European Patent EP 3368914 B1 provides an example thereof. However, the invention is not limited to the configuration described in this document.

[0056] For example, the permanent magnet (2) is configured to generate a static magnetic field having an amplitude of less than 100 mT, preferably less than 65 mT, and more preferably 50 mT or less.

[0057] The imaging system (1) also includes a set of gradient coils (6). The gradient coils (6) are specially configured to generate a magnetic field of small amplitude and change space when current is applied to them.

[0058] More specifically, the gradient coil (6) is aligned parallel to the static magnetic field and is designed to generate a magnetic field component whose amplitude varies linearly depending on the position along one of the x-axis, y-axis, or z-axis (the x-axis, y-axis, and z-axis form an orthogonal reference frame).

[0059] Accordingly, the combined effect of the magnetic field applied by the gradient coil (6) makes it possible to spatially encode the signal coming from the body to be investigated that is within the bore (3). Spatial encoding is manifested, in particular, by fluctuations in the resonance energy of the nuclear spins of hydrogen nuclei contained in the body to be investigated within the analysis zone. In other words, the nuclear spins of hydrogen nuclei receive different magnetic fields depending on the location.

[0060] The imaging system (1) further includes an RF coil (7) configured to function as an RF transmitter and receiver. In particular, at least one RF coil is configured to emit RF energy pulses of a frequency equal to or close to the resonant frequency of hydrogen nucleus spins, which are at least partially absorbed by these nuclei.

[0061] The RF coil (7) may be connected to a pulse generator (10) configured to allow current to flow through the RF coil (7). More specifically, the pulse generator (10) may be configured to generate current pulses within the RF coil (7). The pulse means is also preferably configured to power a gradient coil (6) to spatially encode each of the positions of the body that may exist within the bore (3).

[0062] The RF coil may also be connected to a radio frequency processing means (11) configured to process a radio frequency signal that can be received by an assembly including the RF coil (7).

[0063] The imaging system (1) may include a first interface (12) that connects a pulse generating means (10) to an RF coil (7) on one side and a radio frequency processing means (11) to an RF coil (7) on the other side.

[0064] The imaging device (1) may further include a second interface (13) that provides a link between the pulse generating means (10) and the gradient coil (6).

[0065] The pulse generation means (10), radio frequency processing means (11), first interface (12) and second interface (13) can be controlled by a control unit (14), for example, a computer (14).

[0066] Accordingly, during operation, the RF coil (7) is positioned within the bore (3), and the body to be imaged is positioned within the internal volume of the RF coil (7).

[0067] Accordingly, the present invention includes a method for imaging a part of a human or animal body using a magnetic resonance imaging device, particularly the imaging device (1) described above.

[0068] The imaging process, in particular, involves the use of a belt (50) (shown in FIG. 2 and FIG. 3) that encircles a torso section of the body (60) known as the contact section (51). In a particularly advantageous manner, the belt (50) wraps around the navel of the body (60). Without needing to be explicitly stated, it will be understood that the belt forms a loop around the torso. Additionally, the belt includes two opposite sides, referred to as the first side (50a) and the second side (50b), respectively.

[0069] The belt (50) may include a matrix made of an insulating material, such as a polyamide material.

[0070] According to a first advantageous embodiment, a set of electrically conductive wires referred to as contact wires may be arranged (and / or embedded) within an insulating matrix. In particular, the contact wires are designed to provide electrical contact with a contact section. The contact wires are connected at the same potential as all electrical and electronic elements of the magnetic resonance imaging device during the acquisition of a magnetic resonance image of a part of the human body, thereby allowing the flow of electric charge.

[0071] As illustrated in FIG. 3, the belt (50) also includes an electrical connection means (52) designed to allow the flow of electric charge by connecting the belt (50) to the same potential as all electrical and electronic elements of the magnetic resonance imaging device during the acquisition of a magnetic resonance image of a part of the human body.

[0072] The belt can be 18 cm to 30 cm wide.

[0073] The matrix may include polyamide material.

[0074] Preferably, the connecting wire may include at least one of silver, copper, nickel, or tin.

[0075] The contact wires can be arranged within the matrix such that the belt has a surface electrical resistance of less than 1 ohm per square, preferably less than 0.5 ohms per square, more preferably less than 0.3 ohms per square, and much more preferably less than 0.1 ohms per square.

[0076] Tables 1 and 2 below show noise level measurements obtained for various configurations. In particular, this noise, expressed in microvolts, was measured during the imaging procedure using a magnetic resonance imaging device with the following characteristics.

[0077] ㆍ The belt (50) is positioned around the torso of the individual to image one of the individual's arms (using a 27 cm scanner: see Table 1) or the individual's head (using a 32 cm scanner: see Table 2).

[0078] The main magnetic field is less than 50 mT.

[0079] ㆍ Sequence used to measure noise: Measured with a 20 kHz reception bandwidth (similar to the bandwidth used in clinical sequences) without radio frequency emissions.

[0080] ㆍ Single Dimension Acquisition.

[0081] Calculate the average of the 4 measurements.

[0082] Measure the RMS (root-mean-square) amplitude.

[0083] In these tables, the "Phantom" row corresponds to the noise level obtained when measuring an image of a commercial phantom placed within the imaging device described above. This phantom has dielectric properties similar to those of human tissue. Used for reference purposes, this measurement does not implement the belt described in the present invention.

[0084] The lines labeled "Subject 1" and "Subject 2" correspond to the noise levels obtained when measuring the first subject ("Series 1") and the second subject ("Series 2") placed within the imaging equipment described above. The measurement involves placing a belt (50) around the torsos of the first and second individuals. The measurement corresponds to a belt 22 cm wide. In either case, the belt has a surface electrical resistance of less than 0.5 ohms per square and is connected to ground potential during the measurement. The second column of "Table 1" and "Table 2" shows the noise levels measured without the belt. The third column of "Table 1" and "Table 2" shows the noise levels measured using the belt. Finally, the fourth column of "Table 1" and "Table 2" shows the percentage reduction in noise levels between measurements taken with and without the belt. The measurement is performed according to the procedure described above.

[0085] [Table 1]

[0086]

[0087] [Table 2]

[0088]

[0089] The measurements of "Subject 1" and "Subject 2" taken without a belt show a noise level ranging from 13 microvolts to 16 microvolts when used at 32 cm for head imaging, which is much higher than the reference value.

[0090] Using a belt significantly reduces electronic noise and produces high-quality images.

[0091] Therefore, the inventors were able to demonstrate that positioning the belt (50) around the torso enables relatively efficient dissipation of electric charge regardless of which part of the body is imaged. The resulting reduction in electronic noise improves the resolution of the acquired image, enabling operation even in weak magnetic fields, for example, less than 100 mT or even less than 50 mT.

[0092] The inventors also observed that, for example, positioning a strap made of the same material as a belt and worn around the ankle or wrist does not provide as effective and universal electronic noise reduction as that achieved by the belt embodied in the present invention.

[0093] FIG. 4 illustrates a second embodiment of a belt (50) that can be implemented within the scope of the present invention.

[0094] In particular, the belt according to this second embodiment may include all the features of the belt used in the first embodiment.

[0095] According to this second embodiment, the belt (50) includes a metal structure (53) on its first surface (50a). In particular, this metal structure is configured to have the same potential as all electrical and electronic elements of the magnetic resonance imaging device during the acquisition of a magnetic resonance image of a part of the human body, thereby allowing the flow of charge.

[0096] The metal structure (53) may include at least one of a metal plate such as a sheet, a metal foil such as aluminum foil, and a metal button.

[0097] In the example illustrated in Fig. 4, the metal structure includes a rectangular plate.

[0098] Generally, metal structures can be clipped onto a matrix, bonded, or sewn.

[0099] However, this last embodiment does not limit the invention, and therefore, those skilled in the art can conceive other fastening methods for attaching a metal structure to a first surface based on general knowledge.

[0100] According to the first variant example illustrated in FIG. 4, the metal structure (53) is electrically connected to one another by a bundle of electrically conductive connecting wires, specifically referred to as connecting wires (54), and preferably, the connecting wires comprise at least one material selected from silver, copper, and tin.

[0101] Table 3 below shows the noise level measurements obtained for various configurations. In particular, this noise, expressed in microvolts, was measured during the imaging procedure using a magnetic resonance imaging device with the following characteristics.

[0102] ㆍ A belt (50) is positioned around the torso of the individual's body to image the individual's head (using a 32 cm scanner).

[0103] The main magnetic field is less than 50 mT.

[0104] ㆍ Sequence used to measure noise: Measured with a 20 kHz reception bandwidth (similar to the bandwidth used in clinical sequences) without radio frequency emissions.

[0105] ㆍ Single Dimension Acquisition.

[0106] Calculate the average of the 4 measurements.

[0107] Measure the RMS (root-mean-square) amplitude.

[0108] In Table 3, the "Human Model" row corresponds to the noise level obtained when measuring an image of a commercial human model placed within the imaging device described above. This human model has genetic characteristics similar to those of human tissue. This measurement, used for reference purposes, does not implement the belt described in the present invention.

[0109] The lines labeled "Subject 1" and "Subject 2" correspond to the noise levels obtained when measuring the first and second subjects placed within the imaging equipment described above. The measurement involves placing a belt (50) around the torsos of the first and second individuals. The measurement corresponds to a belt 22 cm wide. In either case, the belt has a surface electrical resistance of less than 0.5 ohms per square and is connected to ground potential during the measurement. The second column shows the noise levels measured without the belt. The third column of Table 3 shows the noise levels measured using the belt of the first embodiment. The fourth column of Table 3 shows the noise measured using the belt according to the first variant of the first embodiment.

[0110] [Table 3]

[0111]

[0112] FIGS. 5 and FIGS. 6 illustrate a first example and a second example of a belt (50) according to a second variation of the second embodiment, respectively.

[0113] In particular, this second variant and all subsequent examples have belts that essentially share the same characteristics as the first variant, but without connecting wires. In particular, the metal structure in the first example comprises a square plate fixed to the matrix with screws, whereas the metal structure in the second example comprises a rectangular copper plate bonded to the matrix.

[0114] According to the present invention, particularly in relation to the second example, the metal structures are rectangular or square in shape and arranged in a checkerboard pattern, and preferably, all metal structures (53) cover at least 85% of the area of ​​the first surface intended to contact the contact section. Furthermore, in this second example, the matrix does not have contact wires.

[0115] Table 4 below shows the noise level measurements obtained for various configurations. In particular, this noise, expressed in microvolts, was measured during the imaging procedure using a magnetic resonance imaging device with the following characteristics.

[0116] ㆍ A belt (50) is positioned around the torso of the individual's body to image the individual's head (using a 32 cm scanner).

[0117] The main magnetic field is less than 50 mT.

[0118] ㆍ Sequence used to measure noise: Measured with a 20 kHz reception bandwidth (similar to the bandwidth used in clinical sequences) without radio frequency emissions.

[0119] ㆍ Single Dimension Acquisition.

[0120] Calculate the average of the 4 measurements.

[0121] Measure the RMS (root-mean-square) amplitude.

[0122] In Table 4, the "Human Model" row corresponds to the noise level obtained when measuring an image of a commercial human model placed within the imaging device described above. This human model has genetic characteristics similar to those of human tissue. This measurement, used for reference purposes, does not implement the belt described in the present invention.

[0123] The lines labeled "Subject 1" and "Subject 2" correspond to the noise levels obtained when measuring the first and second subjects placed within the imaging equipment described above. The measurement involves placing a belt (50) around the torsos of the first and second individuals. As shown in the first and second examples of the second variant, the measurement uses a belt having a width of 22 cm. In either case, the belt has a surface electrical resistance of less than 0.5 ohms per square meter and is connected to ground potential during the measurement. The second column shows the noise levels measured without the belt. The third column shows the noise levels measured using the belt of the first embodiment. The fourth column of Table 4 shows the noise measured using the first belt sample from the second variant, and the fifth column of Table 4 shows the noise measured using the second belt sample from the second variant.

[0124] [Table 4]

[0125]

[0126] The second example of a belt without contact wires (column 4 of Table 4) appears to have reduced performance compared to other belts.

[0127] FIGS. 7 and FIGS. 8 illustrate a third example and a fourth example of a belt (50) according to a second variation of the second embodiment, respectively.

[0128] The metal structure in the third example includes a metal button fixed to the matrix with a screw, whereas the metal structure in the second example includes a metal plate, specifically aluminum, bonded to the matrix.

[0129] According to the present invention, particularly in relation to the fourth example, the matrix does not have a contact wire.

[0130] Table 5 below shows the noise level measurements obtained for various configurations. In particular, this noise, expressed in microvolts, was measured during the imaging procedure using a magnetic resonance imaging device with the following characteristics.

[0131] ㆍ A belt (50) is positioned around the torso of the individual's body to image the individual's head (using a 32 cm scanner).

[0132] The main magnetic field is less than 50 mT.

[0133] ㆍ Sequence used to measure noise: Measured with a 20 kHz reception bandwidth (similar to the bandwidth used in clinical sequences) without radio frequency emissions.

[0134] ㆍ Single Dimension Acquisition.

[0135] Calculate the average of the 4 measurements.

[0136] Measure the RMS (root-mean-square) amplitude.

[0137] In Table 5, the "Human Model" row corresponds to the noise level obtained when measuring an image of a commercial human model placed within the imaging device described above. This human model has genetic characteristics similar to those of human tissue. This measurement, used for reference purposes, does not implement the belt described in the present invention.

[0138] The lines labeled "Subject 1," "Subject 2," and "Subject 3" correspond to the noise levels obtained when measuring the first and second subjects placed within the imaging equipment described above. The measurement involves placing a belt (50) around the torso of the first, second, and third individuals. As shown in the third and fourth examples of the second variant, the measurement uses a belt with a width of 22 cm. In either case, the belt has a surface electrical resistance of less than 0.5 ohms per square meter and is connected to ground potential during the measurement. The second column shows the noise levels measured without the belt. The third column shows the noise levels measured using the belt of the first embodiment. The fourth column of Table 4 shows the noise measured using the third belt sample from the second variant, and the fifth column of Table 4 shows the noise measured using the fourth belt sample from the second variant.

[0139] [Table 4]

[0140]

[0141] Both the third and fourth examples provide acceptable performance.

[0142] FIG. 9 illustrates a final example based on the second variation, which essentially reflects the characteristics of the fourth example. However, in this example, the metal strip is replaced with a metal plate screwed in place.

[0143] The noise level measured in an individual under the same conditions as those listed in the first, second, third, and fourth examples is 0.20 microvolts.

[0144] In general, using a belt significantly reduces noise during head imaging. More specifically, positioning the belt around the abdomen (or even the waist) is the most effective method for reducing noise.

[0145] Contrary to expectations, positioning the belt as close as possible to the magnet (for example, around the patient's neck when imaging the head) is not the best way to effectively reduce noise.

[0146] Accordingly, the present invention also relates to a magnetic resonance imaging device as described in connection with FIG. 1, comprising a belt (50) according to the present invention.

[0147] The present invention also relates to a belt that may essentially include the features described above.

Claims

Claim 1 A method for imaging a part of a human or animal body using a magnetic resonance imaging device (1), wherein the imaging method comprises the use of a belt (50) that surrounds a torso section of the body, referred to as a contact section (51), with one of its own surfaces, referred to as a first surface (50a), wherein the belt (50) is electrically conductive and is set to the same potential as all electrical and electronic elements constituting the magnetic resonance imaging device (1) that use magnetic resonance during the acquisition of a magnetic resonance image of the part of the human body, thereby allowing the flow of electric charge. Claim 2 A method for imaging a part of a human or animal body using a magnetic resonance imaging device (1), wherein the belt (50) comprises a matrix of an electrical insulating material, preferably a polyamide material. Claim 3 A method for imaging a part of a human or animal body using a magnetic resonance imaging device (1), wherein the belt (50) comprises a metal structure (53) on its first surface (50a), and all of the metal structure (53) are at the same potential as all electrical and electronic elements constituting the magnetic resonance imaging device (1) during the acquisition of a magnetic resonance image of the part of the human body, thereby allowing the flow of electric charge. Claim 4 In paragraph 3, the metal structure (53) comprises at least one of a metal plate such as a sheet, a metal foil such as aluminum foil, and a metal button, a method for imaging a part of a human or animal body using a magnetic resonance imaging device (1). Claim 5 A method for imaging a part of a human or animal body using a magnetic resonance imaging device (1), wherein, in paragraph 3 or 4, the metal structure (53) is electrically connected to one another, particularly by a bundle of electrically conductive connecting wires (54), and preferably, the connecting wires (54) comprise at least one material selected from silver, copper and tin. Claim 6 A method for imaging a part of a human or animal body using a magnetic resonance imaging device (1), wherein, in any one of claims 3 to 5, the metal structure (53) is clipped, bonded, or sewn onto the matrix. Claim 7 A method for imaging a part of a human or animal body using a magnetic resonance imaging device (1), wherein, in any one of claims 3 to 6, the metal structure (53) is rectangular or square in shape and arranged in a checkerboard pattern, and preferably, all of the metal structure (53) covers at least 85% of the area of ​​the first surface (50a) intended to contact the contact section (51). Claim 8 A method for imaging a part of a human or animal body using a magnetic resonance imaging device (1), wherein, in any one of claims 3 to 6, the belt (50) comprises a set of contact wires arranged in a matrix, and the contact wires are connected to the same potential as all electrical and electronic elements constituting the imaging device (1) by magnetic resonance during the acquisition of a magnetic resonance image of a part of the human body, allowing the flow of electric charge, and preferably, the contact wires comprise at least one material selected from silver, copper and tin. Claim 9 A method for imaging a part of a human or animal body using a magnetic resonance imaging device (1), wherein, in any one of claims 1 to 8, the imaging method uses a magnetic resonance imaging device (1) equipped with a magnet (2) that defines a space in which a part of the body is positioned internally during magnetic resonance imaging, and the magnet (2) applies a magnetic field of less than 100 mT, more preferably less than 50 mT, during imaging. Claim 10 A method for imaging a part of a human or animal body using a magnetic resonance imaging device (1), wherein, in any one of claims 1 to 9, the part of the body includes a head. Claim 11 A method for imaging a part of a human or animal body using a magnetic resonance imaging device (1), wherein, in any one of claims 1 to 10, the belt (50) has a width of 18 cm to 30 cm. Claim 12 A method for imaging a part of a human or animal body using a magnetic resonance imaging device (1), wherein, in any one of claims 1 to 11, the belt (50) has a surface electrical resistance of less than 1 ohm per square meter, preferably less than 0.5 ohms per square meter, more preferably less than 0.1 ohms per square meter. Claim 13 A magnetic resonance imaging device (1) equipped with a belt (50) designed to provide electrical contact with a contact section (51) of the body's torso, wherein the electrically conductive belt (50) is connected to the same potential as all electrical and electronic elements constituting the magnetic resonance imaging device (1) during the acquisition of a magnetic resonance image of a part of the human body, thereby allowing the flow of electric charge. Claim 14 In paragraph 13, the belt (50) comprises a matrix of an electrical insulating material, preferably a polyamide material, in a magnetic resonance imaging device (1). Claim 15 In claim 13 or 14, the belt (50) comprises a metal structure (53) on its first surface (50a), and all of the metal structure (53) are at the same potential as all electrical and electronic elements constituting the magnetic resonance imaging device (1) during the acquisition of a magnetic resonance image of a part of the human body, thereby allowing the flow of charge, the magnetic resonance imaging device (1). Claim 16 In claim 15, the metal structure (53) comprises at least one of a metal plate such as a sheet, a metal foil, or a metal button, in a magnetic resonance imaging device (1). Claim 17 In claim 15 or 16, the metal structure (53) is electrically connected to one another, particularly by a bundle of electrically conductive connecting wires (54), and preferably, the connecting wires (54) comprise at least one material selected from silver, copper and tin, magnetic resonance imaging device (1). Claim 18 In any one of claims 14 to 17, the metal structure (53) is clipped, bonded, or sewn onto the matrix, magnetic resonance imaging device (1). Claim 19 In any one of claims 14 to 18, the metal structure (53) is rectangular or square in shape and arranged in a checkerboard pattern, preferably, all of the metal structure (53) covers at least 85% of the area of ​​the first surface (50a) intended to contact the contact section (51), magnetic resonance imaging device (1). Claim 20 In any one of claims 14 to 19, the belt (50) comprises an array of contact wires arranged in a matrix, wherein the contact wires are connected to the same potential as all electrical and electronic elements constituting the magnetic resonance imaging device (1) during the acquisition of a magnetic resonance image of a part of the human body to allow the flow of electric charge, and preferably, the contact wires comprise at least one material selected from silver, copper and tin, magnetic resonance imaging device (1). Claim 21 In any one of claims 13 to 20, the belt (50) has a width of 18 cm to 30 cm, magnetic resonance imaging device (1). Claim 22 In any one of claims 13 to 21, the belt (50) has a surface electrical resistance of less than 1 ohm per square, preferably less than 0.5 ohms per square, more preferably less than 0.1 ohm per square, magnetic resonance imaging device (1). Claim 23 A belt (50) intended for use while imaging a part of a human body using a magnetic resonance imaging device (1), comprising a surface referred to as a first surface (50a), designed to provide electrical contact with a contact section (51) of the body's torso through said first surface (50a), being electrically conductive, and allowing the flow of electric charge by being connected to the same potential as all electrical and electronic elements constituting the magnetic resonance imaging device (1) during the acquisition of a magnetic resonance image of said part of the human body. Claim 24 In paragraph 23, a belt (50) comprising a matrix of an electrical insulating material, preferably a polyamide material. Claim 25 In claim 24, the belt (50) comprises a metal structure (53) on its first surface (50a), and all of the metal structure (53) are at the same potential as all electrical and electronic elements constituting the magnetic resonance imaging device (1) during the acquisition of a magnetic resonance image of a part of the human body, thereby allowing the flow of charge, belt (50). Claim 26 In paragraph 25, the metal structure (53) comprises at least one of a metal plate such as a sheet, a metal foil, or a metal button, and is a belt (50). Claim 27 In claim 25 or 26, the metal structure (53) is electrically connected to one another, particularly by a bundle of electrically conductive connecting wires (54), preferably, the connecting wires (54) comprise at least one material selected from silver, copper and tin, belt (50). Claim 28 In any one of claims 25 to 27, the metal structure (53) is a belt (50) that is clipped, bonded, or sewn to the matrix. Claim 29 In any one of claims 25 to 28, the metal structure (53) is rectangular or square in shape and arranged in a checkerboard pattern, preferably, all of the metal structure (53) covers at least 85% of the area of ​​the first surface (50a) intended to contact the contact section (51), belt (50). Claim 30 In any one of claims 25 to 29, the belt (50) comprises a set of contact wires arranged in a matrix, wherein the contact wires are connected at the same potential as the set of electrical and electronic elements constituting the imaging device (1) for acquiring magnetic resonance images of a part of the human body to allow the flow of electric charge, and preferably, the contact wires comprise at least one material selected from silver, copper and tin. Claim 31 In any one of claims 24 to 39, the belt (50) has a width of 18 cm to 30 cm. Claim 32 In any one of claims 24 to 31, the belt (50) has a surface electrical resistance of less than 1 ohm per square, preferably less than 0.5 ohms per square, more preferably less than 0.1 ohm per square.

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