Silica gel composite material for reducing B0 field distortion induced by magnetic conductivity, magnetic resonance earplug as well as preparation method and application of magnetic resonance earplug

Abstract

The invention relates to the technical field of passive shimming in a magnetic resonance system, in particular to a silica gel composite material for reducing B0 field distortion induced by magnetic conductivity, a magnetic resonance earplug and a preparation method and application of the magnetic resonance earplug. The raw materials of the silica gel composite material comprise an agent A, an agent B and a diamagnetic material. When the silica gel composite material is used as an earplug, the uniformity of a magnetic field is optimized for a complex cavity area of a human ear canal part, the problem that B0 shimming of the ear canal area cannot be effectively carried out through built-in second-order shimming in an existing MRI machine is solved, and image artifacts are reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of passive shimming technology in magnetic resonance systems, in particular to a silicone composite material for reducing B0 field distortion induced by magnetic permeability, a magnetic resonance earplug and a preparation method and application thereof. BACKGROUND

[0002] The severe magnetization discontinuity in the human body contact area with air induces B0 field distortion, which further causes serious image artifacts, especially for gradient echo sequences, planar echo sequences and the like which are sensitive to B0 field inhomogeneity. Passive shimming has the characteristics of simplicity, stability and high safety, and ferromagnetic materials are usually installed in the device before it is shipped to perform overall passive shimming, but the control and adjustment are limited; the magnetic field can be described by spherical harmonics, and active shimming can adjust the current in the coil to control the magnetic field in the system. The ear canal area has a high order after the spherical harmonic function decomposition of the magnetic field due to its narrowness, tortuosity and the presence of a large amount of soft tissue and bone structure, and the built-in second-order shimming in the MRI machine cannot effectively improve it. Some magnetic field distribution maps of the baby brain area in the magnetic resonance system with self-provided shimming are provided, such as Figure 16 It can be seen that the contact area with air is the most affected, and the ear canal part is the most seriously affected due to its complex shape. In high-field magnetic resonance, the magnetic field inhomogeneity interferes with gradient echo sequence imaging more seriously.

[0003] The applicant attempts to solve the problem of magnetization discontinuity by using a material similar to the human body magnetic permeability for fitting, extending the contact surface of the human tissue and air, which can effectively solve the problem of magnetization discontinuity at low cost, and further improve the image quality. SUMMARY

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide a silicone composite material for reducing B0 field distortion induced by magnetic permeability, a magnetic resonance earplug and a preparation method and application thereof. In high-field magnetic resonance imaging, the image signal-to-noise ratio and spectral resolution are enhanced with the increase of the magnetic field strength, in order to improve the imaging performance, it is necessary to further improve the magnetic field strength of the MRI system, and the problem of magnetic field uniformity is more important. In functional imaging, the inhomogeneous B0 field mainly exists in the area where the human tissue and air contact, such as the ear canal part, and the problem of B0 field inhomogeneity is more serious in high-field magnetic resonance. The present application optimizes the uniformity of the magnetic field for the complex cavity area of the human ear canal part, solves the problem that the built-in second-order shimming in the current MRI machine cannot effectively perform B0 shimming in the ear canal area, and reduces the image artifacts.

[0005] To achieve the above object and other related objects, the first aspect of the present application provides a silica gel composite material for reducing B0 field distortion induced by magnetic permeability, raw materials of the silica gel composite material comprising an A agent, a B agent and a diamagnetic material, and a mass ratio of the A agent, the B agent and the diamagnetic material being 1:1:(0.18-0.26).

[0006] The present application also provides a preparation method of the aforementioned silica gel composite material for reducing B0 field distortion induced by magnetic permeability, the preparation method comprising mixing the A agent, the B agent and the diamagnetic material to obtain a mixed reagent, pouring the mixed reagent into a mold, constant-temperature solidification, and taking out the silica gel composite material for reducing B0 field distortion induced by magnetic permeability after solidification.

[0007] The present application also provides an application of the aforementioned silica gel composite material for reducing B0 field distortion induced by magnetic permeability in the field of magnetic resonance earplugs, neck pads and forehead pads.

[0008] The present application also provides a magnetic resonance earplug comprising the aforementioned silica gel composite material for reducing B0 field distortion induced by magnetic permeability.

[0009] The present application also provides a preparation method of the aforementioned magnetic resonance earplug, the preparation method comprising mixing the A agent, the B agent and the diamagnetic material to obtain a mixed reagent, pouring the mixed reagent into a 3D-printed earplug mold, constant-temperature solidification, and taking out the magnetic resonance earplug after solidification.

[0010] The present application also provides an application of the aforementioned silica gel composite material for reducing B0 field distortion induced by magnetic permeability and / or the aforementioned magnetic resonance earplug in the field of reducing B0 field distortion induced by magnetic permeability.

[0011] Compared with the prior art, the present application has the following beneficial effects:

[0012] The present application provides a silica gel composite material for reducing B0 field distortion induced by magnetic permeability, which can be used in the field of magnetic resonance earplugs, neck pads and forehead pads. In particular, a special earplug conforming to human engineering is designed for the ear canal area, a new type of special earplug for reducing B0 field distortion induced by magnetic permeability is invented, the combination ratio of the material is optimized, the best combination of imaging quality is found, and the universality and the comfort of the subject are considered. The earplug conforming to human magnetic permeability makes up for the uneven magnetic field area of the ear canal, the experimentally calculated B0 field distribution is improved, the geometric distortion of the planar echo sequence image is corrected, and better image information can be obtained in combination with active shimming. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 A special earplug for reducing B0 field distortion induced by magnetic permeability provided by the present application is shown.

[0014] Figure 2The magnetic field distribution of two slices scanned with the subject 1 wearing the ordinary sponge earplug is shown.

[0015] Figure 3 The magnetic field distribution of two slices scanned with the subject 1 wearing the magnetic resonance special earplug of the present application is shown.

[0016] Figure 4 The 5 continuous slice images scanned with the subject 1 wearing the ordinary sponge earplug in the 3T magnetic field environment using the gradient echo planar sequence are shown.

[0017] Figure 5 The 5 continuous slice images scanned with the subject 1 wearing the magnetic resonance special earplug in the 3T magnetic field environment using the gradient echo planar sequence are shown.

[0018] Figure 6 The magnetic field distribution of two slices scanned with the subject 2 wearing the ordinary sponge earplug in the 3T magnetic field environment is shown.

[0019] Figure 7 The magnetic field distribution of two slices scanned with the subject 2 wearing the magnetic resonance special earplug of the present application in the 3T magnetic field environment is shown.

[0020] Figure 8 The 5 continuous slice images scanned with the subject 2 wearing the ordinary sponge earplug in the 3T magnetic field environment using the gradient echo planar sequence are shown.

[0021] Figure 9 The 5 continuous slice images scanned with the subject 2 wearing the magnetic resonance special earplug in the 3T magnetic field environment using the gradient echo planar sequence are shown.

[0022] Figure 10 The 3D printing earplug mold in the example is shown.

[0023] Figure 11 The hanging ear earplug made by the present application is shown.

[0024] Figure 12 The effect diagram of the hanging ear earplug made by the present application worn on the human ear is shown.

[0025] Figure 13 The magnetic sensitivity of the products obtained by the present application and comparative examples 1-3 and comparative examples 6-8 is shown.

[0026] Figure 14 The shape of the silicone composite material made by the present application and the position fixed on the dummy are shown.

[0027] Figure 15 The magnetic sensitivity map of the pyrolytic graphite crystal per unit volume is shown.

[0028] Figure 16 The magnetic field distribution of the infant brain region is shown in the magnetic resonance system with the built-in shimming.

[0029] Figure 17 The subject 2 wears the ordinary sponge earplug (left) and the magnetic resonance special earplug (right).

[0030] Figure 18 The magnetic field distribution of the two slices obtained by scanning the subject 2 wearing the ordinary sponge earplug in the 5T magnetic field environment is shown.

[0031] Figure 19 The magnetic field distribution of the two slices obtained by scanning the subject 2 wearing the magnetic resonance special earplug in the 5T magnetic field environment is shown.

[0032] Figure 20 The 5 continuous slice images obtained by scanning the subject 2 wearing the ordinary sponge earplug in the 5T magnetic field environment using the gradient echo planar sequence are shown.

[0033] Figure 21 The 5 continuous slice images obtained by scanning the subject 2 wearing the magnetic resonance special earplug in the 5T magnetic field environment using the gradient echo planar sequence are shown. DETAILED DESCRIPTION

[0034] Hereinafter, an embodiment of a silicone composite material for reducing permeability-induced B0 field distortion, a magnetic resonance earplug, and a preparation method and application thereof are specifically disclosed.

[0035] The ranges disclosed herein are defined by their lower and upper limits. Ranges that include both endpoints are inclusive of the endpoints, and ranges that exclude both endpoints are not inclusive of the endpoints. Ranges are combinable, i.e., a range of "a-b" is combinable with a range of "c-d" to form a range of "a-c" and "d-b". For example, if a range of 60-120 and a range of 80-110 are listed, it is understood that a range of 60-110 and 80-120 are also contemplated. Furthermore, if a minimum range value of 1 and 2 are listed, and a maximum range value of 3, 4, and 5 are listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, the use of a numerical range "a-b" to describe a variable indicates that the variable can take on any value within the range, including the end values unless specifically excluded. For example, the numerical range "0-5" indicates that the variable can take on any real value between 0 and 5, inclusive of the values 0 and 5. Also, when a parameter is stated to be an integer > 2, it is equivalent to state that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0036] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0037] The present application is to solve the problem that the built-in second-order shimming in the current MRI machine cannot effectively perform the ear canal region B0 shimming, and reduce the image artifact. Since the human body can be approximated as water, the magnetic susceptibility is about 9.05ppm (parts per million), and after a large number of exploration experiments, it is found that the magnetic susceptibility of pyrolytic graphite powder per unit volume can be as high as -595ppm, so the present application attempts to add pyrolytic graphite powder, that is, pyrolytic graphite powder is added to silica gel to form a mixed new material, and the combination ratio of the material is optimized to find the best combination of imaging quality, considering the universality and the comfort of the subject. The earplug conforming to the magnetic permeability of the human body makes up for the uneven magnetic field region of the ear canal, the B0 field distribution calculated by the experiment is improved, the geometric distortion of the planar echo sequence image is corrected, and better image information can be obtained in combination with active shimming. On this basis, the present application is completed.

[0038] Silica gel composite material for reducing B0 field distortion induced by magnetic permeability

[0039] The first aspect of the present application provides a silica gel composite material for reducing permeability-induced B0 field distortion, raw materials A agent, B agent and diamagnetic material of the earplug, mass ratio of the A agent, B agent and diamagnetic material is 1:1:(0.18-0.26). Alternatively, the mass ratio of the A agent, B agent and diamagnetic material may, for example, be 1:1:(0.18-0.20), 1:1:(0.20-0.26), 1:1:(0.18-0.19), 1:1:(0.18-0.20), 1:1:(0.20-0.22), 1:1:(0.22-0.24) or 1:1:(0.24-0.26) and the like.

[0040] In the silica gel composite material for reducing permeability-induced B0 field distortion provided by the present application, the A agent may, for example, be polydimethylsiloxane (PDMS, [(CH3)2SiO] n In specific embodiments, the A agent may, for example, be TY-866A of Dongguan Huarun Composite Materials.

[0041] In the silica gel composite material for reducing permeability-induced B0 field distortion provided by the present application, the B agent is a cross-linking agent containing polydimethylsiloxane and a catalyst. In specific embodiments, the B agent is TY866B of Dongguan Huarun Composite Materials.

[0042] In the silica gel composite material for reducing permeability-induced B0 field distortion provided by the present application, the diamagnetic material has a magnetic susceptibility of -8.5 ppm per unit volume in the direction perpendicular to the normal of the basal plane of the diamagnetic material crystal. The diamagnetic material has a magnetic susceptibility of -595 ppm to -204 ppm per unit volume in the direction parallel to the normal of the basal plane of the diamagnetic material crystal. The diamagnetic material has a magnetic susceptibility of -204 ppm per unit volume in the powder structure. The normal of the basal plane refers to the normal of the basal plane of the diamagnetic material crystal.

[0043] In the silica gel composite material for reducing permeability-induced B0 field distortion provided by the present application, the diamagnetic material is graphite powder or pyrolytic graphite powder.

[0044] The magnetic susceptibility induced B0 field distortion reducing silicone composite provided by the present application, the magnetic sensitivity of the pyrolytic graphite powder per unit volume in the normal direction of the base plane of the graphite crystal is -8.5ppm. The magnetic sensitivity of the pyrolytic graphite powder per unit volume in the parallel direction of the base plane of the graphite crystal is -595ppm. The magnetic sensitivity of the powdery structure of the pyrolytic graphite powder per unit volume is -204ppm. It should be noted that the magnetic sensitivity of the pyrolytic graphite crystal per unit volume is anisotropic, and each direction has a certain value, for example, the magnetic sensitivity of a pyrolytic graphite sheet measured in the normal direction of the base plane is -8.5ppm, and the magnetic sensitivity in the parallel direction of the base plane is -595ppm, and Figure 15 is the magnetic sensitivity diagram of the pyrolytic graphite crystal per unit volume. However, the pyrolytic graphite powder after mixing can be regarded as uniform in all directions, and the magnetic sensitivity of the three directions is averaged by the following formula, and the calculated value is -204ppm. The formula is wherein the base plane normal refers to the normal direction of the base plane of the graphite crystal.

[0045] The particle size of the pyrolytic graphite powder in the magnetic susceptibility induced B0 field distortion reducing silicone composite provided by the present application is 100-150 mesh. The particle size of the pyrolytic graphite powder can be selected as 100-125 mesh, 125-150 mesh, 100-110 mesh, 110-120 mesh, 120-130 mesh, 130-140 mesh or 140-150 mesh, etc. The advantage of the above particle size range is to disperse more uniformly in the A agent and the B agent, and the disadvantage of the range is that it cannot be well dispersed in the A agent and the B agent.

[0046] The magnetic susceptibility induced B0 field distortion reducing silicone composite provided by the present application, the magnetic sensitivity of the pyrolytic graphite powder per unit volume in the normal direction of the base plane of the graphite crystal is -8.5ppm. The magnetic sensitivity of the pyrolytic graphite powder per unit volume in the parallel direction of the base plane of the graphite crystal is -595ppm. The magnetic sensitivity of the powdery structure of the pyrolytic graphite powder per unit volume is -204ppm. It should be noted that the magnetic sensitivity of the pyrolytic graphite crystal per unit volume is anisotropic, and each direction has a certain value, for example, the magnetic sensitivity of a pyrolytic graphite sheet measured in the normal direction of the base plane is -8.5ppm, and the magnetic sensitivity in the parallel direction of the base plane is -595ppm, and

[0047] The particle size of the pyrolytic graphite powder in the magnetic susceptibility induced B0 field distortion reducing silicone composite provided by the present application is 100-150 mesh. The particle size of the pyrolytic graphite powder can be selected as 100-125 mesh, 125-150 mesh, 100-110 mesh, 110-120 mesh, 120-130 mesh, 130-140 mesh or 140-150 mesh, etc. The advantage of the above particle size range is to disperse more uniformly in the A agent and the B agent, and the disadvantage of the range is that it cannot be well dispersed in the A agent and the B agent.

[0048]

Preparation method of the magnetic susceptibility induced B0 field distortion reducing silicone composite

[0049] The second aspect of the present application provides a preparation method of the silica gel composite material for reducing B0 field distortion induced by magnetic permeability according to the first aspect of the present application, comprising the following steps:

[0050] The preparation method comprises the following steps: mixing the A agent, the B agent and the diamagnetic material to obtain a mixed reagent, pouring the mixed reagent into a mold, constant-temperature solidification, and taking out the silica gel composite material for reducing B0 field distortion induced by magnetic permeability after solidification.

[0051] In the preparation method of the silica gel composite material for reducing B0 field distortion induced by magnetic permeability provided by the present application, the temperature of the constant-temperature solidification is 20-50℃. Alternatively, the temperature of the constant-temperature solidification can be, for example, 20-30℃, 30-40℃, or 40-50℃, etc.

[0052] The selection and dosage of the A agent, the B agent and the diamagnetic material are the same as those described in the first aspect of the present application, which will not be repeated here.

[0053]

Application

[0054] The present application also provides an application of the silica gel composite material for reducing B0 field distortion induced by magnetic permeability according to the first aspect of the present application in the field of magnetic resonance earplugs, neck pads and forehead pads.

[0055]

Magnetic resonance earplug

[0056] The present application also provides a magnetic resonance earplug comprising the silica gel composite material for reducing B0 field distortion induced by magnetic permeability according to the first aspect of the present application.

[0057]

Preparation method of magnetic resonance earplug

[0058] The present application also provides a preparation method of the aforementioned magnetic resonance earplug, which comprises the following steps: mixing the A agent, the B agent and the diamagnetic material to obtain a mixed reagent, pouring the mixed reagent into a 3D-printed earplug mold, constant-temperature solidification, and taking out the magnetic resonance after solidification.

[0059] The selection and dosage of the A agent, the B agent and the diamagnetic material are the same as those described in the first aspect of the present application, which will not be repeated here.

[0060]

Application

[0061] The present application also provides an application of the silica gel composite material for reducing B0 field distortion induced by magnetic permeability according to the first aspect of the present application and the magnetic resonance earplug in the field of reducing B0 field distortion induced by magnetic permeability.

[0062] The beneficial effects of the present application will be further illustrated in the following examples.

[0063] In order to make the invention purposes, technical solutions and beneficial technical effects of the present application clearer, the present application will be described in further detail below in conjunction with examples. However, it should be understood that the examples of the present application are only for the purpose of explaining the present application, and are not intended to limit the present application, and the examples of the present application are not limited to the examples given in the specification. The specific experimental conditions or operation conditions not specified in the examples are made according to the conventional conditions or the conditions recommended by the material suppliers.

[0064] In addition, it should be understood that the one or more method steps mentioned in the present application do not exclude that there can be other method steps before and after the combination steps or other method steps can be inserted between the explicitly mentioned steps, unless otherwise specified; it should also be understood that the combination connection relationship between the one or more devices / apparatuses mentioned in the present application does not exclude that there can be other devices / apparatuses before and after the combination devices / apparatuses or other devices / apparatuses can be inserted between the two explicitly mentioned devices / apparatuses, unless otherwise specified. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the arrangement order of each method step or to limit the range of implementation of the present application, and the change or adjustment of the relative relationship, without substantial change of the technical content, is also regarded as the scope of implementation of the present application.

[0065] In the following examples, the reagents, materials and instruments used are commercially available unless otherwise specified.

[0066] A agent is purchased from Dongguan Huarun Composite Material, model number: TY-866A;

[0067] B agent is purchased from Dongguan Huarun Composite Material, model number: TY866B;

[0068] Pyrolytic graphite powder is purchased from Henan Liugong Graphite Co., Ltd., high-purity pyrolytic graphite;

[0069] Common graphite powder is purchased from Zhongzhi New Material Manufacturing Co., Ltd., conductive lubricating graphite powder.

[0070] Comparative Example 1

[0071] A mixture of 10 g of A agent, 10 g of B agent and 0.1 g of pyrolytic graphite powder is obtained, and then the mixture is placed in a mold and waits for the mixture to solidify at a constant temperature of 50°C. After solidification, the obtained silica gel block (20 mm*20 mm*10 mm) is taken out. After the silica gel block is fixed on the phantom, the field map is scanned to obtain the influence of the silica gel block on the magnetic field in the phantom, and further to obtain the magnetic sensitivity of the silica gel with this graphite concentration.

[0072] Comparative Example 2

[0073] A mixed reagent was prepared by mixing 10g of agent A, 10g of agent B, and 0.3g of pyrolytic graphite powder. The mixture was then placed in a mold and kept at a constant temperature of 50℃ until solidification. After solidification, a silicone block (20mm*20mm*10mm) was removed. The silicone block was then fixed onto a phantom and scanned to obtain a field map. The influence of the silicone block on the magnetic field within the phantom can be calculated using the field map obtained from the phantom, further determining the magnetic susceptibility of this graphite-concentration silicone.

[0074] Comparative Example 3

[0075] 10g of agent A, 10g of agent B, and 0.6g of pyrolytic graphite powder were mixed to obtain a mixed reagent. The mixture was then placed in a mold and kept at a constant temperature of 50℃ until solidification. After solidification, a silicone block (20mm*20mm*10mm) was removed. The silicone block was fixed onto a phantom and scanned to obtain a field pattern. The influence of the silicone block on the magnetic field within the phantom can be calculated using this field pattern, further determining the magnetic susceptibility of this graphite-concentration silicone.

[0076] Comparative Example 4

[0077] 10g of agent A, 10g of agent B, and 1.5g of pyrolytic graphite powder were mixed to obtain a mixed reagent. The mixture was then placed in a mold and kept at a constant temperature of 50℃ until solidification. After solidification, a silicone block (20mm*20mm*10mm) was removed. The silicone block was fixed onto a phantom and scanned to obtain a field pattern. The influence of the silicone block on the magnetic field within the phantom can be calculated using this field pattern, further determining the magnetic susceptibility of this graphite-concentration silicone.

[0078] Example 1

[0079] A mixed reagent was prepared by mixing 10g of agent A, 10g of agent B, and 1.8g of pyrolytic graphite powder. This mixture was then poured into a 3D-printed earplug mold and allowed to solidify at a constant temperature of 50°C. After solidification, the mold was removed to obtain an earplug with reduced magnetic permeability-induced B0 field distortion. The earplug was then fixed onto a phantom and the field map was obtained. The influence of the silicone block on the magnetic field within the phantom can be calculated using the field map obtained from the phantom, further determining the magnetic susceptibility of this graphite-concentrated silicone.

[0080] Example 2

[0081] Mix 10g of agent A, 10g of agent B, and 2g of pyrolytic graphite powder to obtain a mixed reagent, then as follows: Figure 10 The reagent was poured into a 3D-printed earplug mold and kept at a constant temperature of 50°C until it solidified. After solidification, the mold was removed to obtain an earplug with reduced magnetic permeability-induced B0 field distortion. The earplug was then fixed onto a phantom and the field map was obtained by scanning. The influence of the silicone block on the magnetic field in the phantom can be calculated from the field map obtained from the phantom, and the magnetic susceptibility of this graphite-concentration silicone can be further obtained.

[0082] Example 3

[0083] Mixing A agent 10 g, B agent 10 g and 2.6 g of pyrolytic graphite powder to obtain a mixed reagent, then pour into a 3D printed earplug mold, wait for the reagent to solidify in a constant temperature of 50℃, and then take out the earplug to obtain a earplug that reduces the B0 field distortion induced by magnetic susceptibility. After fixing the earplug on the phantom, the field map is scanned to calculate the influence of the silicone block on the magnetic field in the phantom, and further obtain the magnetic sensitivity of the silicone with this graphite concentration. Figure 10

[0084] Comparative Example 5

[0085] Mixing A agent 100 g, B agent 100 g and 50.0 g of pyrolytic graphite powder to obtain a mixed reagent, then pour into a 3D printed earplug mold, wait for the reagent to solidify in a constant temperature of 50℃, and then take out the earplug to obtain a earplug that reduces the B0 field distortion induced by magnetic susceptibility. After fixing the earplug on the phantom, the field map is scanned to calculate the influence of the silicone block on the magnetic field in the phantom, and further obtain the magnetic sensitivity of the silicone with this graphite concentration.

[0086] Comparative Example 6

[0087] Mixing A agent 10 g, B agent 10 g and 0.1 g of graphite powder to obtain a mixed reagent, then in a mold, wait for the reagent to solidify in a constant temperature of 50℃, and then take out the silicone block (20mm*20mm*10mm) obtained. After fixing the silicone block on the phantom, the field map is scanned to calculate the influence of the silicone block on the magnetic field in the phantom, and further obtain the magnetic sensitivity of the silicone with this graphite concentration.

[0088] Comparative Example 7

[0089] Mixing A agent 10 g, B agent 10 g and 0.3 g of ordinary graphite powder to obtain a mixed reagent, then in a mold, wait for the reagent to solidify in a constant temperature of 50℃, and then take out the silicone block (20mm*20mm*10mm) obtained. After fixing the silicone block on the phantom, the field map is scanned to calculate the influence of the silicone block on the magnetic field in the phantom, and further obtain the magnetic sensitivity of the silicone with this graphite concentration.

[0090] Comparative Example 8

[0091] Mixing A agent 10 g, B agent 10 g and 0.6 g of ordinary graphite powder to obtain a mixed reagent, then in a mold, wait for the reagent to solidify in a constant temperature of 50℃, and then take out the silicone block (20mm*20mm*10mm) obtained. After fixing the silicone block on the phantom, the field map is scanned to calculate the influence of the silicone block on the magnetic field in the phantom, and further obtain the magnetic sensitivity of the silicone with this graphite concentration.​

[0092] Example 4

[0093] Mixing A agent 10 g, B agent 10 g and 2 g of common graphite to obtain a mixed agent, and then pouring into a 3D printed earplug mold, waiting for the agent to solidify in a constant temperature of 50℃, and then taking out the common earplug after solidification. Scan the fieldmap after fixing the earplug on the phantom, and calculate the influence of the silica gel block on the magnetic field in the phantom through the fieldmap obtained by the phantom, and further obtain the magnetic sensitivity of the silica gel with this graphite concentration.

[0094] Comparative Example 9

[0095] Using 3M sponge earplug

[0096] Table 1 is the magnetic sensitivity of the silica gel block obtained in Comparative Examples 1-9 and Examples 1-4

[0097]

[0098] As can be seen from Table 1, when the amount of pyrolytic graphite or common graphite powder is too small or too large, the magnetic sensitivity (ppm) is not ideal.

[0099] As Figure 13 can be seen from Comparative Examples 1-3 and Comparative Examples 6-8, the effect of pyrolytic graphite powder is better than that of graphite powder.

[0100] Subject test:

[0101] The silica gel composite material prepared in Example 2 for reducing the B0 field distortion induced by magnetic susceptibility and the 3M sponge earplug of Comparative Example 9 were subjected to scanning experiments.

[0102] Subject 1:

[0103] The magnetic field distribution map of wearing the common sponge earplug of Comparative Example 9 is as follows Figure 2 .

[0104] The magnetic field distribution map of wearing the magnetic resonance special earplug of Example 2 is as follows Figure 3 .

[0105] Improvement of wearing common sponge earplug and magnetic resonance special earplug on gradient echo planar imaging:

[0106] Common sponge earplug: as Figure 4 .

[0107] Magnetic resonance special earplug: as Figure 5 .

[0108] Subject 2:

[0109] 3T magnetic field environment, wearing the magnetic field distribution map of the ordinary sponge earplug of comparative example 9: Figure 6 .

[0110] 3T magnetic field environment, wearing the magnetic field distribution map of the magnetic resonance special earplug of example 2: Figure 7 .

[0111] 5T magnetic field environment, wearing the magnetic field distribution map of the ordinary sponge earplug of comparative example 9: Figure 18 .

[0112] 5T magnetic field environment, wearing the magnetic field distribution map of the magnetic resonance special earplug of example 2: Figure 19 .

[0113] 3T magnetic field environment, wearing ordinary sponge earplug and magnetic resonance special earplug for gradient echo planar imaging:

[0114] 3T magnetic field environment, ordinary sponge earplug: Figure 8 .

[0115] 3T magnetic field environment, magnetic resonance special earplug: Figure 9 .

[0116] 5T magnetic field environment, wearing ordinary sponge earplug and magnetic resonance special earplug for gradient echo planar imaging:

[0117] 5T magnetic field environment, ordinary sponge earplug: Figure 20 .

[0118] 5T magnetic field environment, magnetic resonance special earplug: Figure 21 .

[0119] Comparative example 9 as Figure 2 and 4 , example 2 as Figure 3 and 5 , the first subject as Figure 2 and 3 , the left and right figures are the magnetic field distribution maps of different slices, Figure 2 is the magnetic field distribution map of two slices obtained by scanning the subject wearing ordinary sponge earplug, Figure 3 is the magnetic field distribution map of two slices obtained by scanning the subject wearing magnetic resonance special earplug, by comparing Figure 2 and Figure 3 , it can be found that the magnetic field of the ear region is more uniform when wearing the magnetic resonance special earplug. Figure 4 is the 5 continuous slice images obtained by scanning the subject wearing ordinary sponge earplug using gradient echo planar sequence, Figure 5 is the 5 continuous slice images obtained by scanning the subject wearing magnetic resonance special earplug using gradient echo planar sequence, by comparingFigure 4 and Figure 5 Due to the significant inhomogeneity of the magnetic field, the gradient echo... Figure 4 Signal loss in the ear region of the subjects. Figure 5 The lost signal was recovered, and the red circle marks the area with the most significant improvement.

[0120] For example, in Example 9 Figure 6 , Figure 8 , Figure 18 and Figure 20 Example 2 is as follows Figure 7 , Figure 9 , Figure 19 and Figure 21 Corresponding to the second subject, such as Figure 6 and 7 The left and right images show the magnetic field distribution of different slices under a 3T magnetic field environment. Figure 6 These are magnetic field distribution maps obtained from two slices scanned under a 3T magnetic field environment, with the subjects wearing ordinary foam earplugs. Figure 7 The magnetic field distribution images of two slices were obtained by scanning the subjects under 3T conditions while they wore special MRI earplugs. Figure 6 and Figure 7 It can be observed that the magnetic field in the ear area is more uniform when wearing MRI-specific earplugs; for example... Figure 18 and 19 The left and right images show the magnetic field distribution of different slices under a 5T magnetic field environment. Figure 18 These are magnetic field distribution maps obtained from two slices scanned under a 5T magnetic field environment, with the subjects wearing ordinary foam earplugs. Figure 19 The magnetic field distribution images of two slices were obtained by scanning the subjects with MRI earplugs under a 5T magnetic field environment. Figure 18 and Figure 19 It can be observed that the magnetic field in the ear area is more uniform when wearing a special MRI earplug. Figure 8 Five consecutive slice images were obtained by scanning a plane echo sequence using gradient echo under a 3T magnetic field environment, with the subjects wearing ordinary foam earplugs. Figure 9 In a 3T magnetic field environment, the subjects wore special MRI earplugs, and five consecutive slice images were obtained using a gradient echo planar echo sequence scan for comparison. Figure 8 and Figure 9 Due to the significant inhomogeneity of the magnetic field, the gradient echo... Figure 8 Signal loss in the ear region of the subjects. Figure 9 The lost signal was recovered, and the red circle marks the area with the most significant improvement. Figure 20 Five consecutive slice images were obtained by scanning a plane echo sequence using gradient echo, with the subjects wearing ordinary foam earplugs in a 5T magnetic field environment. Figure 21are 5 continuous slice images obtained by using gradient echo planar sequence scanning under the condition of 5T magnetic field environment, and the contrast Figure 20 and Figure 21 Since gradient echo is obviously affected by magnetic field inhomogeneity, Figure 20 the signal loss in the ear region of the subject in the middle, Figure 21 the lost signal is compensated back, and the red circles mark the areas where the improvement is most obvious.

[0121] The above experiments verify the compensation effect of the earplug of the present application on the B0 field uniformity and the geometric correction of the planar echo sequence scanning image.

[0122] Phantom experiment:

[0123] This part is a supplementary description of the comparative example and the embodiment, the shape of the silicone composite material is made and fixed on the phantom, as shown in Figure 14 .

[0124] The purpose of this phantom experiment is to quantitatively calculate the magnetic susceptibility of this silicone composite material. The magnetic susceptibility of a substance is its own characteristic. In order to explore the magnetic susceptibility of the composite material with different weight ratios of graphite, under the condition of the same weight of silicone (10g of A agent and 10g of B agent), silicone cubes (20mm*20mm*10mm) with 0.1g, 0.2g, 0.3g, 0.4g, 0.5g, 0.6g, 0.7g, 0.8g, 0.9g and 1.0g of high-temperature pyrolysis graphite powder and ordinary graphite powder were respectively made. By fixing the graphite-silicone cube on the cylindrical phantom, the field map affected by the silicone cube can be obtained by scanning the axial surface of the phantom with gradient echo sequence, which represents the cumulative phase of resonant atoms in the echo time, Figure 14 showing the change of the magnetic susceptibility along the y direction of the silicone cubes with 0.1g, 0.3g and 0.6g of high-temperature pyrolysis graphite and ordinary graphite powder added respectively. The specific magnetic susceptibility calculation formula is as follows:

[0125]

[0126] The remanence calculation of the silicone cube is based on the Biot-Savart law. The magnetic field disturbance value obtained by experiment can be used to estimate the remanence of the cube with different proportions, and finally the weight proportion closest to the human magnetic permeability is obtained, wherein the embodiment 2 is closest to the human magnetic permeability.

[0127] Earpiece earplug

[0128] Referring to embodiment 2, an earpiece earplug as described in Figure 11 is made, which is worn on the human ear as shown in Figure 12A cylindrical passive composite silica gel is used to fill the pinna part, which further extends the contact area with the human body to reduce the influence of B0 field inhomogeneity at the human body and air contact surface, while also bearing part of the noise reduction function.

[0129] The above merely describes the preferred embodiments of the present application, and is not intended to limit the present application in any form or in essence. It should be noted that those skilled in the art can make some improvements and supplements without departing from the method of the present application, and these improvements and supplements should also be considered as the protection scope of the present application. For those skilled in the art, some minor changes, modifications and equivalent changes made by utilizing the disclosed technical content without departing from the spirit and scope of the present application are equivalent embodiments of the present application; meanwhile, any equivalent changes, modifications and evolution made according to the essential technology of the present application to the above embodiments are still within the scope of the technical solutions of the present application.

Claims

1. A silicone gel composite material for reducing permeability-induced B0 field distortions, characterized by, The raw materials of the silica gel composite material include A agent, B agent and diamagnetic material, and the mass ratio of the A agent, B agent and diamagnetic material is 1:1: (0.18～0.26)。 2. The silicone gel composite material for reducing permeability-induced B0 field distortion according to claim 1, characterized by, Any one or more of the following features are also included: A1) the A agent is dimethylsiloxane; A2) the B agent is a cross-linking agent containing dimethylsiloxane and a catalyst; A3) the diamagnetic material is graphite powder or pyrolytic graphite powder; A4) the magnetic susceptibility of the diamagnetic material per unit volume in the direction perpendicular to the normal of the basal plane of the diamagnetic material crystal is -8.5 ppm; A5) the magnetic susceptibility of the diamagnetic material per unit volume in the direction parallel to the normal of the basal plane of the diamagnetic material crystal is -595 ppm to -204 ppm; A6) the magnetic susceptibility of the powdery structure of the diamagnetic material per unit volume is -204 ppm.

3. The silicone composite material for reducing permeability-induced B0 field distortions of claim 2, wherein, Any one or more of the following features are also included: A11) the A agent is TY-866A of Dongguan Huarun Composite Material; A21) the B agent is TY866B of Dongguan Huarun Composite Material.

4. The silicone composite material for reducing permeability-induced B0 field distortions of claim 2, wherein, Any one or more of the following features are also included: A31) the magnetic susceptibility of the pyrolytic graphite powder per unit volume in the direction perpendicular to the normal of the basal plane of the graphite crystal is -8.5 ppm; A32) the magnetic susceptibility of the pyrolytic graphite powder per unit volume in the direction parallel to the normal of the basal plane of the graphite crystal is -595 ppm; A33) the magnetic susceptibility of the pyrolytic graphite powder per unit volume in the powdery structure is -204 ppm; A34) the particle size of the pyrolytic graphite powder is 100-150 mesh; A35) the magnetic susceptibility of the graphite powder per unit volume in the direction perpendicular to the normal of the basal plane of the graphite crystal is -8.5 ppm; A36) the magnetic susceptibility of the graphite powder per unit volume in the direction parallel to the normal of the basal plane of the graphite crystal is -204 ppm; A37) the magnetic susceptibility of the graphite powder per unit volume in the powdery structure is -74 ppm; A38) the particle size of the graphite powder is 320-800 mesh.

5. The method of claim 1 to 4, wherein the silicone gel composite is prepared by the steps of: a) mixing a silicone fluid, a cross-linking agent, and a filler to form a mixture; b) curing the mixture to form a cured silicone gel; c) mixing the cured silicone gel with a magnetic material to form a silicone gel composite; and d) curing the silicone gel composite to form a cured silicone gel composite. The preparation method includes mixing the A agent, B agent and diamagnetic material to obtain a mixed reagent, pouring the mixed reagent into a mold, constant-temperature solidification, and taking out the silica gel composite material after solidification to obtain a silica gel composite material for reducing B0 field distortion induced by magnetic susceptibility.

6. The preparation method of the silica gel composite material for reducing B0 field distortion induced by magnetic susceptibility according to claim 5, wherein the temperature of the constant-temperature solidification is 20-50°C.

7. The silica gel composite material for reducing B0 field distortion induced by magnetic susceptibility according to any one of claims 1-4, which is applied in the field of magnetic resonance earplugs, neck pads and forehead pads.

8. A magnetic resonance earplug, characterized by, The silica gel composite material for reducing B0 field distortion induced by magnetic susceptibility according to any one of claims 1-4 is included.

9. The method of claim 8, wherein the magnetic resonance earplug is prepared by, The preparation method includes mixing the A agent, B agent and diamagnetic material to obtain a mixed reagent, pouring the mixed reagent into a 3D-printed earplug mold, constant-temperature solidification, and taking out the magnetic resonance earplug after solidification.

10. The silica gel composite material for reducing B0 field distortion induced by magnetic susceptibility according to any one of claims 1-4 and / or the magnetic resonance earplug according to claim 8, which is applied in the field of reducing B0 field distortion induced by magnetic susceptibility.

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