Receiving coil unit

Abstract

To provide a receiving coil unit that offers advantages in terms of adhesion to the area to be examined in the oral cavity and in terms of hygiene. [Solution] A receiving coil unit for receiving magnetic resonance signals generated from a subject, comprising a head unit placed in the oral cavity of the subject, and a cable extending from the head unit, wherein the head unit comprises at least one loop coil element and a covering portion that covers the at least one loop coil element and forms the outer shape of the head unit, the covering portion having a contact surface that contacts the area to be examined, the at least one loop coil element being arranged so that its loop surface is along the contact surface and having flexibility in the direction in which the loop surface curves, and the covering portion being made of silicone elastomer.

Description

Technical Field

[0001] The present invention relates to magnetic resonance imaging (MRI) technology.

Background Art

[0002] In a magnetic resonance imaging apparatus, a technique of using a reception coil specialized for a specific part of a subject to obtain an image of that part is known. Patent Document 1 and Patent Document 2 disclose reception coils to be inserted into the oral cavity.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Many oral lesions such as oral cancer occur in soft tissues and have a high risk of malignancy and metastasis. Accurately diagnosing these lesions at an early stage is extremely important for improving the prognosis. MRI plays a central role in the diagnosis of soft tissue lesions and can depict lesions with higher contrast than X-ray examinations such as CT.

[0005] On the other hand, since the oral soft tissue frequently undergoes deformation due to the swallowing movement of saliva, it is necessary to finish imaging before saliva accumulates and is swallowed. In order to acquire high-resolution images in a shorter time, it is important to bring the reception coil into close contact with the lesion. In practical oral MRI imaging, a method of using a large facial coil that covers the entire face has been proposed, but there is a distance between the facial coil and the face, making it difficult to obtain a locally high-definition image.

[0006] When placing receiving coils in the oral cavity, the oral soft tissues have complex shapes with many gentle curves and significant individual differences. Therefore, there are many disadvantages in terms of receiving coil placement. Saliva contains a wide variety and large amount of bacteria and viruses, as well as disease-related exudates and blood, so special attention is required for disinfection and contamination prevention.

[0007] The object of the present invention is to provide a receiving coil unit that offers advantages in terms of adhesion to the area to be examined in the oral cavity and in terms of hygiene. [Means for solving the problem]

[0008] According to the present invention, A receiving coil unit that receives magnetic resonance signals generated from a subject, A head unit placed inside the subject's oral cavity, A cable extending from the head unit, The head unit is At least one loop coil element, A covering portion that covers at least one of the loop coil elements and forms the outer shape of the head unit, The covering portion has a contact surface that comes into contact with the area to be inspected. The at least one loop coil element is arranged such that its loop surface is aligned with the contact surface, and the loop surface is flexible in the direction of curvature. The aforementioned coating is formed of a silicone elastomer. A receiving coil unit characterized by the above is provided. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a receiving coil unit that offers advantages in terms of adhesion to the area to be examined in the oral cavity and in terms of hygiene. [Brief explanation of the drawing]

[0010] [Figure 1] A schematic diagram of a magnetic resonance imaging apparatus to which the present invention can be applied. [Figure 2] Exploded perspective view of a receiving coil device according to an embodiment of the present invention. [Figure 3] Explanatory diagram of the internal structure of a receiving coil unit according to an embodiment of the present invention. [Figure 4] Explanatory diagram of the internal structure of the receiving coil unit of FIG. 3. [Figure 5] Circuit diagram of two receiving coil units. [Figure 6] Cross-sectional view of the support member along the line A-A of FIG. 2. [Figure 7] Diagram showing an example of wearing the receiving coil device of FIG. 2 on a subject. [Figure 8] Diagram of the wearing example of FIG. 7 viewed from the upper jaw side. [Figure 9] Diagram of the wearing example of FIG. 7 viewed from the right cheek side. [Figure 10] Cross-sectional view taken along the line B-B of FIG. 9. [Figure 11] External view of a receiving coil unit according to another embodiment. [Figure 12] (A) is an explanatory diagram of the internal structure of the receiving coil unit of FIG. 11, and (B) is a cross-sectional view taken along the line C-C of FIG. 12(A). [Figure 13] (A) and (B) are diagrams showing an example of use of the receiving coil unit of FIG. 11. [Figure 14] (A) and (B) are respectively explanatory diagrams of the internal structure of a receiving coil unit according to yet another embodiment.

Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims, and not all combinations of the features described in the embodiments are essential for the invention. Two or more of the features described in the embodiments may be arbitrarily combined. Also, the same or similar configurations are denoted by the same reference numerals, and redundant explanations are omitted.

[0012] <First Embodiment> <Outline of a Magnetic Resonance Imaging Apparatus> Figure 1 is a schematic diagram of a magnetic resonance imaging (MRI) apparatus 100 to which the receiving coil device of the present invention can be applied. The MRI apparatus 100 includes a movable table 101 on which a patient 200 lies. The movable table 101 moves the patient 200 in and out of the cavity 106 of the cylindrical magnet section 102. The magnet section 102 is equipped with a superconducting coil 103 that generates a static magnetic field in the cavity 106, a gradient coil 104 that generates a magnetic field gradient in the cavity 106, and a transmitting coil 105 that transmits an RF signal.

[0013] The receiving coil device 1 is placed inside the oral cavity of the subject 200 and is equipped with an RF coil that receives magnetic resonance signals generated from the subject 200. In this embodiment, an existing MRI device is used as the MRI device 100, and by adding the receiving coil device 1, it is possible to obtain multi-faceted tomographic images of the oral cavity of the subject 200.

[0014] The receiving coil device 1 is equipped with multi-channel coils for independent channels. The receiving coil device 1 of this embodiment is equipped with loop coil elements C1 to C4 corresponding to 4 channels (CH1 to CH4). Loop coil elements C1 to C4 are sometimes referred to as elements C1 to C4.

[0015] The magnetic resonance signals received by each element C1 to C4 are processed by the signal processing circuit 120 and input to the control device 110. The signal processing circuit 120 includes an amplifier 121, a filter 122, a detection circuit 123, and an A / D converter 124 for each element C1 to C4.

[0016] The control device 110 is an electronic circuit comprising a processor, a storage device that stores a program to be executed by the processor, and an interface with peripheral devices. The control device 110 is connected to an input device 111 such as a pointing device, keyboard, or touch panel that can be operated by the user, and a display device 112. The control device 110 controls the MRI device 100 according to the user's instructions, reconstructs a tomographic image of the oral lesion of the subject 200 from the magnetic resonance signal received by the receiving coil device 1, and displays it on the display device 112.

[0017] The control device 110 may transfer the tomographic image data to a predetermined destination via a communication line. The destination may be, for example, another department within the hospital where the MRI device 100 is installed (such as an operating room or the relevant department), or it may be another hospital or research facility. Alternatively, instead of transmitting the tomographic image data via a communication line, the control device 110 may store the tomographic image data on a storage medium such as a CD-R and send the storage medium. Personal information may be anonymized during storage.

[0018] <Receiving coil device> Figure 2 is an exploded perspective view of a receiving coil device 1 according to one embodiment of the present invention. The receiving coil device 1 comprises receiving coil units 2A and 2B and a support member 3, and is a configuration example suitable for examination of teeth and gums when attached to the dental arch. Receiving coil unit 2A comprises a head unit 10 having elements C1 and C3 and a cable 20 extending from the head unit 10. Receiving coil unit 2B also comprises a head unit 10 having elements C2 and C4 and a cable 20 extending from the head unit 10. The support member 3 is attached to a part of the dental arch of the subject 200 and detachably supports each head unit 10. First, the receiving coil units 2A and 2B will be described.

[0019] <Receiving coil unit> Receiving coil units 2A and 2B have similar structures. Here, we will explain the structure in detail using receiving coil unit 2A as an example, with reference to Figures 3 and 4 in addition to Figure 2. Figures 3 and 4 are explanatory diagrams of the internal structure of receiving coil unit 2A. In Figures 2 to 4, arrows X, Y, and Z indicate three mutually orthogonal directions and are a coordinate system conveniently set up to explain the structure of receiving coil unit 2A, etc.

[0020] The head unit 10 has an external shape that allows it to be installed in various parts of the oral cavity of the subject 200, and in this embodiment, it has an overall plate-like external shape. In other words, the external shape of the head unit 10 can also be described as a pad shape, a tablet shape, or a thin shape. Installation sites include the sides of the maxillary or mandibular dentition (between the dentition and the cheek, between the dentition and the lip, or between the dentition and the tongue), the underside or the top side of the tongue. In this embodiment, the head unit 10 has a structure particularly suitable for the sides of the dentition when used in combination with the support member 3. However, the receiving coil units 2A and 2B can also be used without using the support member 3.

[0021] The head unit 10 has two regions in the Z direction with different widths (thicknesses) in the Y direction. One of these is a coil housing section 10a with a relatively thin thickness, and the other is a circuit housing section 10b with a relatively thick thickness. Elements C1 and C3 are arranged from the coil housing section 10a to the circuit housing section 10b, and electronic components related to elements C1 and C3 (capacitors 13, adjustment circuits 14, signal lines SL, etc.) are arranged in the circuit housing section 10b.

[0022] The thickness Ty1 of the coil housing 10a is, for example, within the range of 1.5 to 4.5 mm. To give an example of a narrower range, it is within the range of 2.5 to 3.5 mm, and to give an example of a specific thickness, it is 3.0 mm. By setting the thickness Ty1 within this range, even if the coil housing 10a is placed in a deep position on the side of the dental arch, the feeling of a foreign body felt by the subject 200 can be reduced. The thickness Ty2 of the circuit housing 10b is, for example, within the range of 3.0 to 7.0 mm. To give an example of a narrower range, it is within the range of 4.0 to 6.0 mm, and to give an example of a specific thickness, it is 5.0 mm.

[0023] The head unit 10 has a contact surface SF1 that contacts the area to be examined on the subject 200, and an opposite surface SF2. The contact surface SF1 is a flat surface (XZ plane). By making the contact surface SF1 a flat surface, the fit to the area to be examined on the subject 200 can be improved. The opposite surface SF2 has a step at the boundary between the coil housing portion 10a and the circuit housing portion 10b. Of the opposite surface SF2, the coil housing portion 10a and the circuit housing portion 10b are both flat surfaces (XZ plane), and the step is a step in the Y direction.

[0024] An engaging portion 16 is formed on the opposite surface SF2, which engages with the support member 3. By engaging the engaging portion 16 with the support member 3, the head unit 10 is more firmly supported by the support member 3. In this embodiment, the engaging portion 16 has the shape of a protrusion that projects in the Y direction from the opposite surface SF2, and has a pyramidal shape or wedge shape with a small cross-sectional area at the base and a large cross-sectional area at the tip. The engaging portion 16 also has the function of positioning the head unit 10 in the X and Z directions relative to the support member 3. Furthermore, the engaging portion 16 also has a rotation prevention function that restricts the rotation of the head unit 10 around the Y axis relative to the support member 3.

[0025] The head unit 10 of this embodiment has a rectangular shape with the longer side in the X direction and the shorter side in the Z direction. The head unit 10 may also have a circular shape. However, a rectangular shape makes it easier to secure a wider examination area in both the dental arch direction and the depth direction when the head unit 10 is placed on the side of the dental arch.

[0026] The width Wx in the X direction and the width Wz in the Z direction of the head unit 10 are in the relationship Wx > Wz. The width Wx is, for example, within the range of 20.0 mm to 40.0 mm, or a narrower range is within the range of 25.0 to 35.0 mm, or a specific width is 30.0 mm. The width Wz is, for example, within the range of 15.0 mm to 35.0 mm, or a narrower range is within the range of 20.0 to 30.0 mm, or a specific width is 25.7 mm.

[0027] The head unit 10 of this embodiment has a rounded rectangle shape, with rounded corners 10c and 10d. When the head unit 10 is placed on the side of the patient's teeth, the feeling of a foreign object felt by the patient 200 can be reduced. The corner 10c on the coil housing 10a side has a larger radius of curvature than the corner 10d on the circuit housing 10b side. When the coil housing 10a is placed in a deep position on the side of the teeth, the corner 10c with the larger radius of curvature comes into contact with the patient 200, further reducing the feeling of a foreign object felt by the patient 200. The radius of the corner 10c is, for example, in the range of 2.0 mm to 6.0 mm, and a narrower range is 3.0 to 5.0 mm, with a specific example being 4.0 mm. The corners 10c and 10d may have a chamfered shape instead of being rounded.

[0028] The receiving coil unit 2A comprises elements C1 and C3. Elements C1 and C3 have a single-turn loop shape, and in this embodiment, they are rectangles with the X direction as the shorter side and the Z direction as the longer side. The outer shape of elements C1 and C3 may also be circular. However, a rectangle makes it easier to secure a wider receiving area in both the tooth row direction and the depth direction, for example, when the head unit 10 is placed on the side of the tooth row.

[0029] The width CWx of the element C1 in the X direction and the width CWz in the Z direction are in the relationship of CWx < CWz. The width CWx is, for example, a width within the range of 9.0 mm to 15.0 mm, and more specifically, a width within the range of 11.0 to 13.0 mm if a narrower range is exemplified, and, for example, 12.0 mm if a specific width is exemplified. The width CWz is, for example, a width within the range of 12.0 mm to 22.0 mm, and more specifically, a width within the range of 14.0 to 18.0 mm if a narrower range is exemplified, and, for example, 15.0 mm or 17.0 mm if a specific width is exemplified. When inspecting the vicinity of the dental arch, at least one tooth and its surrounding periodontal tissues can be included in the detection range by such dimensions. The element C3 also has similar dimensions, and about three teeth and their surrounding periodontal tissues can be included in the detection range by the elements C1 and C3.

[0030] The elements C1 and C3 of the present embodiment are rounded quadrilaterals of the same shape. The elements C1 and C3 are composed of, for example, a metal wire with a diameter of about 0.3 mm to 0.7 mm. When a relatively thick metal wire is used, when the head unit 10 is arranged on the side of the dental arch of the subject 200, the subject 200 may feel its hardness. By rounding the corners of the elements C1 and C3, the foreign body sensation felt by the subject 200 can be reduced when the head unit 10 is arranged on the side of the dental arch of the subject 200.

[0031] The elements C1 and C3 are arranged at substantially the same position in the Z direction and at displaced positions in the X direction. By arranging the elements C1 and C3 at displaced positions in the X direction, it is easier to secure a wider inspection area. In the case of the present embodiment, the elements C1 and C3 are arranged so as to have an overlapping region P in the X direction. Interference between the elements C1 and C3 can be suppressed. The width of the region P in the X direction is, for example, a width within the range of 1.5 mm to 3.5 mm, and more specifically, a width within the range of 2.0 to 3.0 mm if a narrower range is exemplified, and, for example, 2.5 mm if a specific width is exemplified.

[0032] The loop surfaces CF of elements C1 and C3 are aligned with the contact surface SF1, and in this embodiment, they are parallel (XZ plane). The axial direction AX of each loop of elements C1 and C3 is the normal direction to the loop surface CF, which is the Y direction.

[0033] The receiving coil unit 2A has a covering portion 15. The covering portion 15 integrally comprises a head covering portion 15a that covers the entire head unit 10 and a cable covering portion 15b that covers a part of the cable 20. The head covering portion 15a covers each component of the head unit 10 (elements C1 and C3, and electronic components (12-14, SL)) and forms the outer shape of the head unit 10, including the engaging portion 16. The cable covering portion 15b covers the cable 20 from the side of the head unit 10 within a predetermined range. The cable covering portion 15b is designed to cover at least the portion of the cable 20 that enters the oral cavity of the subject 200.

[0034] The material of the covering portion 15 is a silicone elastomer, for example, a biocompatible silicone elastomer (dental silicone elastomer). The elastic strain range of the covering portion 15 according to ISO standards is, for example, 2 to 20%, and the permanent strain range is, for example, 0 to 6%. By using a silicone elastomer as the covering portion 15, the foreign body sensation felt by the subject 200 when the head unit 10 etc. is placed in the oral cavity of the subject 200 can be reduced.

[0035] As described above, elements C1 and C3 are made of metal wire and are flexible in the direction in which the loop surface CF curves (axial direction AX (in-plane / out-of-plane direction)). Since the flexible elements C1 and C3 are covered with a silicone elastomer coating 15, the head unit 10 (especially the coil housing 10a) as a whole is flexible in any direction in the in-plane / out-of-plane direction of the contact surface SF1. For example, as shown in Figure 2 for the receiving coil unit 2B, it is bendable or curved in the d1 and d2 directions around the virtual line Z1 in the Z direction. It is also bendable or curved in the d3 and d4 directions around the virtual line X1 in the X direction.

[0036] The contact surface SF1 is naturally flat and can take on any curved shape due to the flexibility of the head unit 10. The contact surface SF1 can be made to adhere closely to relatively complex shapes within the oral cavity, and furthermore, the elasticity of the covering portion 15 itself allows it to adhere closely to even minute shapes. Since elements C1 and C3 can be positioned closer together along the area to be examined, the image quality of the magnetic resonance image can be improved. Furthermore, due to the physical properties of silicone, the covering portion 15 may appear in the magnetic resonance image depending on the location of the tomography, but the position of this appearance can be used as a factor in determining whether elements C1 and C3 are positioned in the appropriate location.

[0037] Furthermore, by covering and sealing the head unit 10, which is placed inside the oral cavity, with a covering portion 15 made of silicone elastomer, disinfection and other procedures can be easily performed. This prevents bacteria, viruses, saliva, and blood from entering the inside of the head unit 10, and allows for hygienic reuse. Thus, the receiving coil units 2A and 2B of this embodiment are advantageous in terms of adhesion to the examination target area inside the oral cavity and in terms of hygiene.

[0038] The electrical circuit configuration of receiving coil units 2A and 2B will be explained with reference to Figures 3 to 5. Figure 5 is a circuit diagram of receiving coil units 2A and 2B. Each element C1 to C4 is formed by a single-turned conductor 11 that is formed in a loop shape, and multiple capacitors 12 are inserted (connected in series) in the middle of the loop to adjust the resonant frequency. Each end of element C1 is connected to a capacitor 13, and a resonant circuit is formed by element C1 and capacitor 13.

[0039] The voltage across the terminals of capacitor 13 is output to a pair of signal lines SL via adjustment circuit 14. Adjustment circuit 14 comprises a coil 14a directly connected to one of the pair of signal lines SL and a diode 14b connected between the pair of signal lines SL, and is a circuit for preventing magnetic coupling with the transmitting coil 105.

[0040] Cable 20 consists of two coaxial cables. Cable 20 of receiving coil unit 2A includes a coaxial cable with a pair of signal lines SL (core wire and shield wire) corresponding to element C1 and a coaxial cable with a pair of signal lines SL (core wire and shield wire) corresponding to element C3. Similarly, cable 20 of receiving coil unit 2B includes a coaxial cable with a pair of signal lines SL (core wire and shield wire) corresponding to element C2 and a coaxial cable with a pair of signal lines SL (core wire and shield wire) corresponding to element C4. The two cables 20 are connected to connector 4. Connector 4 is connected to control device 110.

[0041] <Support member> The support member 3 will be described with reference to Figures 2 and 6. Figure 6 is a cross-sectional view along line AA in Figure 2, which is a cross-sectional view of the support member 3 in the ZY plane at the center in the X direction. The support member 3 is a member that straddles the tooth row and supports two head units 10 on the sides of the tooth row.

[0042] The support member 3 comprises a pair of coil support portions 31 spaced apart in the Y direction, and a base portion 32 provided between the pair of coil support portions 31 and sandwiched between the upper and lower teeth of the subject 200. Each coil support portion 31 has a contact surface 31a that abuts against the opposite side of the head unit 10 and is a plate-shaped portion extending in the Z direction from the base portion 32. The contact surfaces 31a of the pair of coil support portions 31 face each other. The two head units 10 and the teeth of the subject 200 are sandwiched between the contact surfaces 31a of the pair of coil support portions 31.

[0043] The coil support portion 31 forms a slot 37 between itself and the base portion 32. A portion of the head unit 10 is inserted into and held in the slot 37. The contact surface 31a has an engaging portion 36 that engages with the engaging portion of the head unit 10. The engaging portion 36 is a recess with the same shape as the engaging portion 16, and has a pyramidal or wedge shape with a large cross-sectional area on the bottom side and a small cross-sectional area on the open end side.

[0044] The base portion 32 includes a bridge portion 33 installed between a pair of coil support portions 31, a tooth-shaped portion 34 formed on one side of the bridge portion 33 in the Z direction, and a tooth-shaped portion 35 formed on the other side. The tooth-shaped portions 34 and 35 have tooth impressions of the upper or lower jaw of the subject 200.

[0045] The material of the support member 3 is, for example, a silicone elastomer, more specifically, a biocompatible silicone elastomer (dental silicone elastomer). The support member 3 may be formed from the same material as a whole, or it may be formed from materials with different properties. In this embodiment, the pair of coil support parts 31 and the bridge part 33 are formed from the same biocompatible silicone, while the tooth-shaped parts 34 and 35 are formed from a biocompatible silicone that is softer than the pair of coil support parts 31 and the bridge part 33. By selecting such materials, the rigidity of the pair of coil support parts 31 and the bridge part 33 that support the head unit 10 can be improved, and the tooth-shaped parts 34 and 35 that come into contact with the subject 200 can reduce the feeling of foreign body sensation felt by the subject 200. When biocompatible silicone is used as the material for the covering part 15, biocompatible silicone with the same properties as the tooth-shaped parts 34 and 35 may be used.

[0046] <Example of installation> An example of attaching the receiving coil device 1 to a subject 200 will be described. Figure 7 shows the area around the mouth of subject 200 in an example of attachment. In the illustrated example, a portion of the right mandibular dentition 202 and the surrounding periodontal tissue are the target areas for examination. For this reason, the receiving coil device 1 is positioned in the oral cavity 201 of subject 200 between the right mandibular dentition 202 and the maxillary dentition 203. To stabilize the shape of subject 200's mouth, a mouthpiece 5 having a thickness similar to the base portion 32 of the support member 3 is placed between the left mandibular dentition 202 and the maxillary dentition 203. The cable 20 is routed from inside the oral cavity 201 to the outside, and the portion that comes into contact with subject 200 is covered by the cable sheathing portion 15b.

[0047] Refer to Figures 8 to 10. Figure 8 is a view of the arrangement of the receiving coil device 1 in Figure 7 from the upper jaw side of the subject 200, with a portion of the support member 3 shown by dashed lines. Figure 9 is a view of the arrangement of the receiving coil device 1 in Figure 7 from the right cheek side of the subject 200, with a portion of the support member 3 shown in a translucent manner. Figure 10 is a cross-sectional view of Figure 9 along line BB. In the illustrated example, the detection target area is a portion of the right mandibular dentition 202 (the three posterior teeth) and the surrounding periodontal tissue, and it is assumed that tomographic images of multiple surfaces from the tooth crown to the tooth root and the surrounding gingiva will be obtained.

[0048] When installing the receiving coil device 1, the head units 10 of the receiving coil units 2A and 2B are first mounted on the support member 3. The head units 10 are inserted into the slots 37 and mounted on the support member 3. During installation, the engaging portion 16 is fitted into the engaging portion 36, thereby more firmly supporting the head unit 10 on the coil support portion 31. In the head unit 10, the circuit housing portion 10b is entirely covered by the coil support portion 31, but the coil housing portion 10a is entirely exposed. This makes it easier for the coil housing portion 10a to come into close contact with the inspection target area, and as a result of elements C1 to C4 being closer to the inspection target area, a clearer image can be obtained.

[0049] Next, the support member 3, which supports the two head units 10, is attached to a portion of the mandibular dentition 202. In the illustrated example, the head unit 10 of receiving coil unit 2A is positioned on the outer side of the dentition, and the head unit 10 of receiving coil unit 2B is positioned on the inner side of the dentition. Regarding the relationship between the XYZ coordinate system used in Figures 2 to 4 and the dentition 202, the receiving coil device 1 is positioned such that the X direction aligns with the dentition direction D1 of the dentition 202 at the site to be examined, and the Z direction aligns with the vertical direction D2 of the teeth.

[0050] The tip of the coil housing portion 10a of each head unit 10 is inserted into deep positions on the sides of the dental arch 202 (the valley between the cheek tissue and gum, the valley between the gum and lip, and the valley between the tongue and gum). This allows the detection range to extend to deeper positions. On the other hand, the coil housing portion 10a is thin, the corners 10c are rounded, and the material of the covering portion 15 is silicone elastomer, which reduces the feeling of a foreign body experienced by the subject 200.

[0051] Because the support member 3 and head unit 10 are flexible, they fit the area to be examined. As shown in Figure 10, the two head units 10 are mounted at a slightly angled position to match the shape of the teeth and gums.

[0052] The contact surface SF1 of each head unit 10 faces and is in contact with the area to be inspected. Therefore, the loop surfaces CF of each element C1 to C4 face the area to be inspected, and their axial direction AX is directed in a direction intersecting the tooth alignment direction D1. Elements C1 and C3 are positioned outside the tooth alignment 202, offset in the tooth alignment direction D1, and are positioned so that they partially overlap. Similarly, elements C2 and C4 are positioned inside the tooth alignment 202, offset in the tooth alignment direction D1, and are positioned so that they partially overlap.

[0053] The opposite side SF2 of each head unit 10 is located on the opposite side (buccal or lingual side) of the area to be examined. Because there is relatively more space on the opposite side, the presence of the engaging portion 16 and the coil support portion 31 helps to minimize discomfort for the subject 200.

[0054] The base portion 32 of the support member 3 is sandwiched between the teeth of the upper jaw dentition 203 and the teeth of the lower jaw dentition 202. When the subject 200 loosely bites down on the base portion 32 with their upper and lower teeth, the shape of the subject's mouth is stabilized, and the position of each element C1 to C4 is prevented from shifting during the reception of magnetic resonance signals. Since the base portion 32 does not contain any elements C1 to C4 or related circuit components, even if the subject 200 bites down on the base portion 32 relatively strongly, it will not adversely affect the reception of magnetic resonance signals or damage each element C1 to C4. Because tooth-shaped portions 34 and 35 are formed on the base portion 32, the base portion 32 fits the upper and lower teeth of the subject 200, giving the subject 200 a sense of security and preventing the position of each element C1 to C4 from shifting during the reception of magnetic resonance signals.

[0055] As described above, the receiving coil device 1 is attached to the subject 200, and the examination is performed using the MRI device 100. Since the receiving coil device 1 of this embodiment is equipped with a multi-channel coil, high-quality magnetic resonance images can be obtained for the area to be examined in a shorter time. Completing the examination in a shorter time reduces the burden on the subject 200. Obtaining high-quality magnetic resonance images improves the accuracy and quality of the diagnostic image.

[0056] The receiving coil device 1 of this embodiment not only has a multi-channel coil, but also employs a structure that distributes elements C1 to C4 to the outer and inner sides of the dentition 202. This allows multiple elements C1 to C4 to be efficiently arranged in the narrow oral cavity. Since elements C1 to C4 are not present between the upper and lower teeth, even if the subject 200 moves their upper and lower jaws, it does not affect elements C1 to C4.

[0057] While reducing the loop area of ​​each element C1 to C4 increases sensitivity, it may shorten the detection range in the axial direction AX. By arranging elements C1 to C4 on the outside and inside of the tooth row 202 as in this embodiment, at least half of the detection range in the tooth width direction intersecting the tooth row direction D1 can be covered by elements C1 and C3, and at least the remaining half can be covered by elements C2 and C4, thereby obtaining a wide detection range with high sensitivity.

[0058] Since the support member 3 and each head unit 10 are detachable, the support member 3 is manufactured individually for each of the 200 patients, while the receiving coil units 2A and 2B can be disinfected and reused. This reduces the cost associated with using the coil receiving device 1, thereby lowering treatment costs.

[0059] <Second Embodiment> The head unit 10 can be made even thinner and its flexibility can be improved. The receiving coil units 2A and 2B of this embodiment will be described with reference to Figures 11 to 12(B). Figure 11 is an external view of the receiving coil units 2A and 2B of this embodiment. Since the receiving coil units 2A and 2B have similar structures, the receiving coil unit 2A will be described mainly. Figure 12(A) is an explanatory diagram of the internal structure of the receiving coil unit 2A, and Figure 12(B) is a cross-sectional view and a partially enlarged view along the CC line of Figure 12(A). In the following description, the explanation of contents common to the first embodiment will be omitted, and the differences will be described mainly.

[0060] The head unit 10 includes an insulating flexible sheet 17. The flexible sheet 17 is, for example, a polyimide substrate and has a thickness of, for example, 25 microns. The flexible sheet 17 includes a rectangular element support portion 17a and a strip-shaped signal line support portion 17b extending from the element support portion 17a.

[0061] The element support portion 17a supports element C1 and its electronic components 12-14 on its surface and element C3 and its electronic components 12-14 on its back surface. In this embodiment, elements C1 and C3 are formed from loop-shaped conductive films 11' formed on a flexible sheet 17 instead of metal wires. The conductive film 11' is, for example, a copper film, with a thickness of, for example, 18 microns and a width of, for example, 2-3 mm. Similar to the first embodiment, elements C1 and C3 are arranged to have overlapping regions in the X direction, but the flexible sheet 17 is interposed between element C1 and element C3.

[0062] With the above configuration, the head unit 10 of this embodiment has a coil housing section 10a thickness Ty1 that is, for example, in the range of 0.5 to 1.0 mm. The circuit housing section 10b thickness Ty2 is in the range of 1.0 to 3.0 mm by using thinner electronic components 12 to 14.

[0063] In this embodiment, elements C1 and C3, together with the flexible sheet 17, are flexible in the direction in which the loop surface CF curves (axial direction AX (in-plane / out-plane direction)). Since the flexible elements C1 and C3 are covered with a silicone elastomer coating 15, the head unit 10 (especially the coil housing portion 10a) as a whole is flexible in any direction in the in-plane / out-plane direction of the contact surface SF1. Moreover, it has higher flexibility than the head unit 10 of the first embodiment, and since it is formed to be thinner, the degree of freedom in installation in the oral cavity can be improved.

[0064] In this embodiment, the element support portion 17a has a rectangular shape without holes, but it is sufficient that it can support the conductive film 11' that forms elements C1 and C3, so it may have a shape with holes in the openings on the inside of elements C1 and C3, or it may have a shape consisting only of the part that supports elements C1 and C3 and electronic components 12-14, etc.

[0065] The signal line support portion 17b forms part of the cable 20. In this embodiment, the cable 20 is constructed by connecting the signal line support portion 17b and the coaxial cable 20b. A pair of signal lines SL' corresponding to element C1 are formed on the surface of the signal line support portion 17b with a linear conductive film, and a pair of signal lines SL' corresponding to element C3 are formed on the back surface of the signal line support portion 17b with a linear conductive film (not shown). The signal line support portion 17b and the end of the coaxial cable 20b are covered by the cable sheathing portion 15b of the sheathing portion 15, and the portion that comes into contact with the subject 200 is covered by the sheathing portion 15.

[0066] In this embodiment, the end of the cable 20 on the head unit 10 side is formed by the signal line support portion 17b, etc., so it is highly flexible. When the head unit 10 is placed in the oral cavity of the subject 200, the cable 20 deforms flexibly, which can reduce the subject's discomfort with the cable 20.

[0067] Figure 13(A) shows an example of the mounting of the receiving coil units 2A and 2B of this embodiment. The example in Figure 13(A) assumes that a tongue cancer lesion is the target site for detection, and shows an example in which the receiving coil unit 2B is installed under the tongue of the subject 200 and the receiving coil unit 2A is installed on top of the tongue. The lower receiving coil unit 2B contacts the underside of the tongue with its contact surface SF1 facing upward, and the upper receiving coil unit 2A contacts the surface of the tongue with its contact surface SF1 facing downward. Since the head units 10 of the receiving coil units 2A and 2B are thin and highly flexible, the contact surface SF1 can be made to adhere closely to the lesion while alleviating discomfort to the subject 200.

[0068] The receiving coil units 2A and 2B of this embodiment can also be used in combination with another receiving coil unit placed outside the oral cavity. Figure 13(B) shows an example of using the receiving coil unit 2A in combination with another receiving coil unit 300. The example in Figure 13(B) assumes that a lesion of lip cancer is the target site for detection, and the receiving coil unit 2A is placed between the outside of the right mandibular dentition 202 of the subject 200 and the lip, and the receiving coil unit 300 is placed outside the lip of the subject 200. The receiving coil unit 2A is installed with the contact surface SF1 facing outward. Because the head unit 10 is thin and highly flexible, the head unit 10 can be fitted into the narrow space between the outside of the mandibular dentition 202 and the lip, and the contact surface SF1 can be brought into close contact with the inside of the lip. The receiving coil unit 300 can be a known unit used for head or facial examinations, for example, but it is also possible to use the receiving coil unit 2B (or 2A) instead.

[0069] <Third Embodiment> Another example using the flexible sheet 17 as in the second embodiment will be described. Figure 14(A) is an explanatory diagram of the internal structure of the receiving coil unit 2C of this embodiment. The differences from the receiving coil unit 2A of the second embodiment will be explained.

[0070] In this embodiment, element C1', which replaces element C1, is formed concentrically by a plurality of conductive films 11'. Each conductive film 11' is similar in shape, and in this embodiment, three rectangular conductive films 11' are formed. The inner conductive film 11' is positioned inside the outer conductive film 11', and each conductive film 11' forms a multiple rectangle. Each conductive film 11' may also form a multiple circle.

[0071] In this embodiment, one element C1' is formed of multiple conductive films 11', and there are gaps between adjacent conductive films 11', which allows the transmitted wave to pass through more easily and improves image quality.

[0072] In the example shown in Figure 14(A), the loop coil element C1' is formed only on the surface of the flexible sheet 17. However, as in the second embodiment, elements similar to element C1' may also be formed on the back surface, and these may overlap in the X direction.

[0073] <Fourth Embodiment> Another example using the flexible sheet 17 as in the second embodiment will be described. Figure 14(B) is an explanatory diagram of the internal structure of the receiving coil unit 2D of this embodiment. The differences from the receiving coil unit 2A of the second embodiment will be explained.

[0074] In this embodiment, the flexible sheet 17 has a large element support portion 17a. The element support portion 17a is large enough to cover, for example, the tongue of a subject 200. Multiple loop coil elements are formed on the surface of the element support portion 17a. In this embodiment, six loop coil elements C21 to C26 are formed. Each element C21 to C26 is formed of a conductive film 11', similar to the second embodiment. The signal line support portion 17b has the signal lines SL' of each element C21 to C26 formed in an aggregated manner.

[0075] In this embodiment, since multiple loop coil elements C21 to C26 are arranged on the large element support section 17a, a wide area can be simultaneously examined by a single receiving coil unit 2C. It can be used to cover both the top and bottom surfaces of the subject's tongue, or it can be used to wrap around the tongue.

[0076] In the example shown in Figure 14(B), loop coil elements C21 to C26 are formed only on the surface of the flexible sheet 17. However, as in the second embodiment, the same number or different numbers of loop coil elements as C21 to C26 may be formed on the back surface, and at least some sets of loop coil elements on the front and back surfaces may overlap.

[0077] Although embodiments of the invention have been described above, the invention is not limited to the above embodiments, and various modifications and changes are possible within the scope of the gist of the invention.

Claims

1. A receiving coil unit that receives magnetic resonance signals generated from a subject, A head unit placed inside the subject's oral cavity, A cable extending from the head unit, The head unit is At least one loop coil element, A covering portion that covers at least one of the loop coil elements and forms the outer shape of the head unit, The covering portion has a contact surface that comes into contact with the area to be inspected. The at least one loop coil element is arranged such that its loop surface is aligned with the contact surface, and the loop surface is flexible in the direction of curvature. The aforementioned coating is formed of a silicone elastomer. A receiving coil unit characterized by the following features.

2. A receiving coil unit according to claim 1, The head unit is a plate-shaped unit, In the natural state of the head unit, the contact surface is a flat surface. A receiving coil unit characterized by the following features.

3. A receiving coil unit according to claim 1, The head unit is covered by the covering portion and includes a flexible sheet positioned along the contact surface, The at least one loop coil element is formed as a conductive film on the flexible sheet. A receiving coil unit characterized by the following features.

4. A receiving coil unit according to claim 3, A first conductive film is formed on the surface of the flexible sheet, forming a first loop coil element. A second conductive film is formed on the back surface of the flexible sheet, which forms a second loop coil element. A receiving coil unit characterized by the following features.

5. A receiving coil unit according to claim 4, The first loop coil element and the second loop coil element overlap in part. A receiving coil unit characterized by the following features.

6. A receiving coil unit according to claim 3, A loop-shaped first conductive film and a second conductive film are formed on the flexible sheet to form a first loop coil element. The second conductive film is located inside the first conductive film. A receiving coil unit characterized by the following features.

7. A receiving coil unit according to claim 3, The flexible sheet includes a cable portion that forms part of the cable, A conductive film is formed on the cable portion, which forms part of the signal line. A receiving coil unit characterized by the following features.

8. A receiving coil unit according to claim 1, The covering portion also covers the portion of the cable that is inside the oral cavity. A receiving coil unit characterized by the following features.

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