Magnetic particle imaging device

Abstract

A magnetic particle imaging device is provided with: a detection coil (3) for detecting a magnetic change in magnetic particles (1); a compensation coil (4) having a central axis (CA) common to the detection coil (3) and connected to the detection coil (3) with opposite polarity; a first winding tube (21) that holds the detection coil (3); and a second winding tube (22) that holds the compensation coil (4). The distance in the direction of the central axis (CA) of the detection coil (3) and the compensation coil (4) can be changed by increasing or decreasing the contact portion of the first winding tube (21) and the second winding tube (22).

Description

Technical Field

[0001] This disclosure relates to magnetic particle imaging apparatus. Background Technology

[0002] Previously, it was known that a compensation coil could be moved separately from the detection coil used for detecting magnetism.

[0003] For example, in the magnetic sensor described in Patent Document 1, a thread is formed between the surface of the winding tube of the compensation coil and the inner wall of the winding tube of the excitation coil, so that by rotating the compensation coil, the compensation coil can be moved slightly along the inner side of the excitation coil.

[0004] Existing technical documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 8-338864 Summary of the Invention

[0006] In Patent Document 1, the winding cylinder of the compensation coil is brought into contact with the winding cylinder of the excitation coil, and the position of the compensation coil is changed while the winding cylinder of the excitation coil supports the winding cylinder of the compensation coil. Depending on the number of excitation coils, detection coils, compensation coils, or their configuration, it is sometimes impossible to bring the winding cylinder of the compensation coil into contact with the winding cylinder of the excitation coil for support.

[0007] Therefore, the purpose of this disclosure is to provide a magnetic particle imaging device that enables the position of the compensation coil relative to the detection coil to change without having the winding cylinder of the compensation coil contact the winding cylinder of the excitation coil.

[0008] A magnetic particle imaging apparatus determines the spatial distribution of magnetic particles within an object to be inspected in an inspection area. The apparatus comprises: an alternating current magnetic field applying coil that generates an alternating current magnetic field that alters the magnetism of the magnetic particles; a direct current magnetic field applicator that generates a region with low magnetic field strength in a manner that alters the magnetism of magnetic particles only in arbitrary areas of the object to be inspected; a detection coil for detecting the magnetic changes of the magnetic particles; a compensation coil having a common central axis with the detection coil and connected to the detection coil with opposite polarity; a first winding tube for holding the detection coil; and a second winding tube for holding the compensation coil. The apparatus is configured such that the distance in the direction of the central axis of the detection coil and the compensation coil can be varied by increasing or decreasing the contact portion of the first and second winding tubes.

[0009] According to this disclosure, the position of the compensation coil relative to the detection coil can be changed without making the winding drum of the compensation coil contact the winding drum of the excitation coil. Attached Figure Description

[0010] Figure 1This is a diagram showing the structure of the magnetic particle imaging device according to Embodiment 1.

[0011] exist Figure 2 In the diagram, (a) is a view of the AC magnetic field applying coil 5, detection coil 3, and compensation coil 4 of Embodiment 1 from one direction. (b) is a view of the AC magnetic field applying coil 5, detection coil 3, and compensation coil 4 of Embodiment 1 from another direction.

[0012] Figure 3 This is a diagram showing the structure of the first winding tube 21 and the second winding tube 22.

[0013] Figure 4 This is a diagram showing the structure of the first winding tube 21 and the second winding tube 22.

[0014] Figure 5 This is a diagram showing the state in which the first winding tube 21 and the second winding tube 22 are in contact.

[0015] Figure 6 This is a diagram showing the first winding tube 21 viewed from another direction.

[0016] Figure 7 This is a diagram showing the structure of the magnetic particle imaging device according to Embodiment 2.

[0017] exist Figure 8 In the diagram, (a) is a view of the AC magnetic field applying coils 5a and 5b, detection coils 3a and 3b, and compensation coils 4a and 4b of Embodiment 2 from one direction. (b) is a view of the AC magnetic field applying coils 5a and 5b, detection coils 3a and 3b, and compensation coils 4a and 4b of Embodiment 2 from another direction.

[0018] Figure 9 This is a diagram showing the construction of the first winding tube 42 and the second winding tube 62.

[0019] Figure 10 This is a diagram showing the construction of the first winding tube 42 and the second winding tube 62.

[0020] Figure 11 This diagram shows the state in which the first winding tube 42 and the second winding tube 62 are in contact. Detailed Implementation

[0021] Implementation method 1.

[0022] Figure 1 This is a diagram showing the structure of the magnetic particle imaging device according to Embodiment 1.

[0023] The magnetic particle imaging device determines the spatial distribution of magnetic particles within the object being inspected in the inspection area.

[0024] The magnetic particle imaging device includes an AC magnetic field applicator 11, a DC magnetic field applicator 6, and a magnetization distribution measuring device 12.

[0025] An alternating magnetic field applicator 11 applies an alternating magnetic field to an imaging area on which the object to be inspected 2 is placed. The alternating magnetic field causes a change in the magnetism of the magnetic particles 1. Specifically, the alternating magnetic field applicator 11 includes an alternating power supply 10 and an alternating magnetic field application coil 5 connected to the alternating power supply 10 and used to excite the alternating magnetic field.

[0026] The DC magnetic field applicator 6 generates a region with a low magnetic field strength by changing the magnetism of the magnetic particles 1 in only an arbitrary area of ​​the object under inspection 2. Specifically, the DC magnetic field applicator 6 generates a low magnetic field region, such as a linear near-zero magnetic field region (FFL), by changing the magnetism of the magnetic particles 1 contained in the object under inspection 2. The DC magnetic field applicator 6 forms a linear near-zero magnetic field region (FFL) in the imaging region where the object under inspection 2 is placed. The DC magnetic field applicator 6 is, for example, composed of two permanent magnets arranged facing each other with opposite magnetization directions. Alternatively, the DC magnetic field applicator 6 may also be two permanent magnets or electromagnets with yokes that are magnetized facing each other.

[0027] The magnetization distribution measuring device 12 measures the magnetic changes of the magnetic particles 1. The magnetization distribution measuring device 12 includes a detection coil 3, a compensation coil 4, and a measuring device 13.

[0028] The detection coil 3 detects the magnetic changes of the magnetic particle 1.

[0029] The compensation coil 4 shares a central axis with the detection coil 3 and is connected to the detection coil 3 with opposite polarities. The winding direction of the detection coil 3 is opposite to that of the compensation coil 4. The compensation coil 4 can be used to cancel out and ignore the influence of the magnetic flux generated by the alternating magnetic field applied to the coil 5.

[0030] In the case of magnetic particle imaging, the measurement position is scanned by changing the relative position of the linear near-zero magnetic field region FFL formed by the DC magnetic field applicator 6 relative to the object under inspection 2. To change the relative position, there are methods for mechanically moving the DC magnetic field applicator 6, the AC magnetic field application coil 5, the detection coil 3, and the compensation coil 4, and methods for mechanically moving the object under inspection 2.

[0031] The signal generated in the detection coil 3 by the AC magnetic field applicator 11 is set as AC1.

[0032] The signal generated in the compensation coil 4 by the AC magnetic field applicator 11 is set as AC2.

[0033] Let M1 be the signal generated in the detection coil 3 by the magnetic particle 1.

[0034] The signal generated in the compensation coil 4 by the magnetic particle 1 is designated as M2.

[0035] The following shows the signal V1 generated by the detection coil 3.

[0036] V1=AC1+M1 …(1)

[0037] The following shows the signal V2 generated by the compensation coil 4.

[0038] V2=AC2+M2 …(2)

[0039] The output of the measuring device 13 is a signal ΔV representing the difference between the signal V1 generated by the detection coil 3 and the signal V2 generated by the compensation coil 4.

[0040] ΔV=V1-V2=(AC1+M1)-(AC2+M2)…(3)

[0041] Figure 2 (a) is a diagram showing the AC magnetic field application coil 5, detection coil 3 and compensation coil 4 of Embodiment 1 viewed from one direction. Figure 2 (b) is a diagram of the AC magnetic field application coil 5, detection coil 3 and compensation coil 4 of embodiment 1 viewed from another direction.

[0042] The object under inspection 2 contains magnetic particles 1. An AC magnetic field application coil 5 is configured to incorporate the magnetic particles 1, the object under inspection 2, a detection coil 3, and a compensation coil 4.

[0043] The common central axis CA of the AC magnetic field applying coil 5, the detection coil 3, and the compensation coil 4 is oriented in the X-axis direction. Magnetic particles 1 are disposed inside the detection coil 3. The linear near-zero magnetic field region FFL formed by the DC magnetic field applicator 6 is oriented in the Y-axis direction.

[0044] To perform magnetic particle imaging, the DC magnetic field applicator 6, AC magnetic field application coil 5, detection coil 3, and compensation coil 4 are configured to rotate in the YZ plane, such that the central axis CA of the coil and the linear near-zero magnetic field region FFL can rotate in the XY plane. Alternatively, the object 2 containing the magnetic particles 1 can also be rotated in the YZ plane.

[0045] The magnetic imaging apparatus of this embodiment has a structure that allows the distance between the detection coil 3 and the compensation coil 4 in the direction of the central axis CA to change. Details will be described below.

[0046] Figures 3-6 This is a diagram illustrating a configuration that allows the distance between the detection coil 3 and the compensation coil 4 to vary along the central axis CA. Figure 3 as well as Figure 4 This is a diagram showing the structure of the first winding tube 21 and the second winding tube 22. Figure 5 This is a diagram showing the state in which the first winding tube 21 and the second winding tube 22 are in contact. Figure 6 This is a diagram showing the first winding tube 21 viewed from another direction.

[0047] The first winding 21 holds the detection coil 3. The second winding 22 holds the compensation coil 4. Both the first winding 21 and the second winding 22 are made of an insulating material. By increasing or decreasing the contact portion between the first winding 21 and the second winding 22, the distance between the detection coil 3 and the compensation coil 4 along the central axis CA can be varied.

[0048] The following provides a more specific structural example.

[0049] The first winding tube 21 has a recess 23. The second winding tube 22 has a protrusion 24. The recess 23 and the protrusion 24 face each other. The central axis of the recess 23 and the protrusion 24 is CA. The recess 23 is formed in the direction of the central axis CA toward the second winding tube 22. The protrusion 24 is formed in the direction of the central axis CA toward the first winding tube 21. By configuring the recess 23 to contact the side of the protrusion 24 and varying the degree to which the protrusion 24 enters the recess 23, the contact portion between the first winding tube 21 and the second winding tube 22 can be increased or decreased.

[0050] A first groove 26 is formed on the side of the protrusion 24. That is, the protrusion 24 has an external thread formed on its outer periphery. A second groove 25 is formed on the side of the recess 23. That is, the recess 23 has an internal thread formed on its inner periphery.

[0051] The first groove 26 and the second groove 25 are formed in a spiral shape. With the protrusion of the first groove 26 in contact with the groove of the second groove 25, and the groove of the first groove 26 in contact with the protrusion of the second groove 25, while rotating the protrusion 24, the protrusion 24 is inserted into the recess 23 or pulled out of the recess 23, thereby enabling the distance between the detection coil 3 and the compensation coil 4 in the direction of the central axis CA to change continuously.

[0052] Alternatively, an adhesive solid material, such as sealing tape, can be pasted onto the surfaces of the first groove 26 and the second groove 25. This improves the positional retention force.

[0053] It can also be configured such that the position of one of the first winding tube 21 and the second winding tube 22 is fixed, while the position of the other can be changed.

[0054] For example, it can be configured such that the position of the first winding tube 21 is fixed by fixing the first winding tube 21 to a winding tube (not shown) that holds the AC magnetic field applied by the coil 5, thereby allowing the position of the second winding tube 22 to change. In this case, the detection coil 3 forms a moving surface in a region with low magnetic field strength, such as a linear near-zero magnetic field region FFL.

[0055] As described above, according to this embodiment, by increasing or decreasing the contact portion between the first winding tube 21 and the second winding tube 22, the distance between the detection coil 3 and the compensation coil 4 in the direction of the central axis CA can be varied. Therefore, without having the second winding tube 22 holding the compensation coil 4 contact the winding tube (not shown) of the coil 5 that holds the alternating magnetic field, the position of the compensation coil 4 relative to the detection coil 3 can be varied.

[0056] A variation of implementation method 1.

[0057] In the above embodiment, the first winding tube 21 is provided to have a recess 23 and the second winding tube 22 is provided to have a protrusion 24, but it is not limited to this. Alternatively, the first winding tube 21 may have a protrusion 24 and the second winding tube 22 may have a recess 23.

[0058] In the above embodiment, a second groove 25 is formed on the side of the recess 23, and a first groove 26 is formed on the side of the protrusion 24, but this is not a limitation. Alternatively, instead of forming grooves on the side of the recess 23 and the side of the protrusion 24, the protrusion 24 can be inserted into the recess 23 like a piston, or inserted and removed from the recess 23, thereby allowing the distance between the detection coil 3 and the compensation coil 4 in the direction of the central axis CA to change. This is because even without grooves, the recess 23 and the protrusion 24 can be held in place without positional displacement by friction or by threads used for fixing.

[0059] In the above embodiment, by forming a spiral second groove 25 on the side of the recess 23 and a spiral first groove 26 on the side of the protrusion 24, the distance between the detection coil 3 and the compensation coil 4 can be continuously varied, but this is not a limitation. It is also possible to vary the distance between the detection coil 3 and the compensation coil 4 in several stages.

[0060] Implementation method 2.

[0061] Figure 7 This is a diagram showing the structure of the magnetic particle imaging apparatus according to Embodiment 2. The magnetic particle imaging apparatus includes a DC magnetic field applicator 6, an AC magnetic field applicator 11A, and a magnetization distribution measuring device 12A.

[0062] The AC magnetic field applicator 11A applies an AC magnetic field to the imaging area on which the object 2 is placed. The AC magnetic field applicator 11A includes an AC power supply 10 and an AC magnetic field application coil pair 51 connected to the AC power supply 10 for energizing the AC magnetic field. The AC magnetic field application coil pair 51 consists of AC magnetic field application coils 5a and 5b connected in series.

[0063] The magnetization distribution measuring device 12A measures the magnetic changes of magnetic particles. The magnetization distribution measuring device 12A includes a detection coil pair 31, a compensation coil pair 41, and a measuring device 13A. The detection coil pair 31 consists of detection coils 3a and 3b connected in series. The compensation coil pair 41 consists of compensation coils 4a and 4b connected in series.

[0064] Detection coils 3a and 3b detect changes in the magnetic properties of magnetic particle 1.

[0065] Compensating coils 4a and 4b share a central axis CB with detection coils 3a and 3b, and are connected to them with opposite polarities. The winding directions of detection coils 3a and 3b are opposite to those of compensating coils 4a and 4b. The compensating coils 4a and 4b can be used to cancel out and ignore the influence of the magnetic flux generated by the alternating magnetic field applied to coils 5a and 5b.

[0066] In the case of magnetic particle imaging, the measurement position is scanned by changing the relative position of the linear near-zero magnetic field region FFL formed by the DC magnetic field applicator 6 relative to the object under inspection 2. To change the relative position, there are methods for mechanically moving the DC magnetic field applicator 6, the AC magnetic field application coil pair 51, the detection coil pair 31, and the compensation coil pair 41, and methods for mechanically moving the object under inspection 2.

[0067] The signal generated in the detection coil pair 31 by the AC magnetic field applicator 11A is set as AC1.

[0068] The signal generated in the compensation coil pair 41 by the AC magnetic field applicator 11A is set as AC2.

[0069] The signal generated in the detection coil pair 31 by the magnetic particle 1 is set as M1.

[0070] The signal generated in the compensation coil pair 41 by the magnetic particle 1 is set as M2.

[0071] The following shows the signal V1 generated by the detection coil 31.

[0072] V1=AC1+M1 …(1)

[0073] The following shows the signal V2 generated by the compensation coil 41.

[0074] V2=AC2+M2 …(2)

[0075] The output of the measuring instrument 13A represents the signal ΔV, which is the difference between the signal V1 generated by the detection coil pair 31 and the signal V2 generated by the compensation coil pair 41.

[0076] ΔV=V1-V2=(AC1+M1)-(AC2+M2)…(3)

[0077] Figure 8 (a) is a diagram showing the AC magnetic field application coils 5a and 5b, detection coils 3a and 3b, and compensation coils 4a and 4b of Embodiment 2 viewed from one direction. Figure 8 (b) is a diagram of the AC magnetic field application coils 5a and 5b, detection coils 3a and 3b, and compensation coils 4a and 4b of Embodiment 2, viewed from another direction.

[0078] A detection coil pair 31 is configured such that a magnetic particle 1 and an object 2 containing the magnetic particle 1 are sandwiched between them. The detection coil pair 31 includes detection coils 3a and 3b. Detection coils 3a and 3b sandwich the magnetic particle 1 and the object 2 between them.

[0079] A compensation coil pair 41 is configured such that a magnetic particle 1, an object under inspection 2, and a detection coil pair 31 are sandwiched between them. The compensation coil pair 41 includes compensation coils 4a and 4b. Compensation coils 4a and 4b sandwich the magnetic particle 1, the object under inspection 2, the detection coil 3a, and the detection coil 3b between them.

[0080] An AC magnetic field applying coil pair 51 is configured to sandwich a magnetic particle 1, an object under inspection 2, a detection coil pair 31, and a compensation coil pair 41. The AC magnetic field applying coil pair 51 includes AC magnetic field applying coils 5a and 5b. The AC magnetic field applying coils 5a and 5b sandwich the magnetic particle 1, the object under inspection 2, the detection coil 3a, the detection coil 3b, the compensation coil 4a, and the compensation coil 4b.

[0081] The AC magnetic field applying coil pair 51, the detection coil pair 31, and the compensation coil pair 41 share a common central axis CB. The direction of the AC magnetic field is the first direction (X-axis direction). The axes perpendicular to the X-axis are the Y-axis and the Z-axis.

[0082] The direction of the linear near-zero magnetic field region FFL formed by the DC magnetic field applicator 6 is made approximately parallel to the first direction (X-axis direction). That is, the angle between the direction of the linear near-zero magnetic field region FFL and the first direction (X-axis direction) is within a range of ±5°. More preferably, the direction of the linear near-zero magnetic field region FFL can also be made to be the first direction (X-axis direction). Furthermore, the basic position of the linear near-zero magnetic field region FFL overlaps with the common central axis CB.

[0083] The distance between AC magnetic field applying coil 5a and AC magnetic field applying coil 5b is D1. The distance between compensation coil 4a and compensation coil 4b is D2. The distance between detection coil 3a and detection coil 3b is D3. Wherein, D1>D2>D3. The coil radius of AC magnetic field applying coil 5a and AC magnetic field applying coil 5b is R1. The coil radius of compensation coil 4a and compensation coil 4b is R2. The coil radius of detection coil 3a and detection coil 3b is R3. Wherein, R1>R2=R3.

[0084] To perform magnetic particle imaging, the DC magnetic field applicator 6, the AC magnetic field application coil pair 51, the detection coil pair 31, and the compensation coil pair 41 are configured to rotate in the XZ plane so that the central axis CB, the direction of the AC magnetic field, and the linear near-zero magnetic field region FFL can rotate. Alternatively, the object 2 containing the magnetic particles 1 can also be rotated in the XZ plane.

[0085] In order to perform magnetic particle imaging, the DC magnetic field applicator 6 is moved so that the linear near-zero magnetic field region FFL moves horizontally to the left and right around its basic position, in addition to rotating.

[0086] The magnetic imaging apparatus of this embodiment has a structure that allows the distance between the detection coil 3a and the compensation coil 4a along the central axis CB direction to change. Details will be described below.

[0087] Figures 9-11 This is a diagram illustrating a configuration that allows the distance between the detection coil 3a and the compensation coil 4a to vary along the central axis CB. Figure 9 as well as Figure 10 This is a diagram showing the construction of the first winding tube 42 and the second winding tube 62. Figure 11 This diagram shows the state in which the first winding tube 42 and the second winding tube 62 are in contact.

[0088] The first winding tube 42 holds the detection coil 3a, the detection coil 3b, and the compensation coil 4b. The second winding tube 62 holds the compensation coil 4a. Both the first winding tube 42 and the second winding tube 62 are made of an insulating material. The first winding tube 42 has a protrusion 34. The second winding tube 62 has a recess 33. The protrusion 34 and the recess 33 face each other. The central axis of the recess 33 and the protrusion 34 is CB. The protrusion 34 is formed in the direction of the central axis CB toward the second winding tube 62. The recess 33 is formed in the direction of the central axis CB toward the first winding tube 42. By configuring the components such that the side surfaces of the protrusion 34 and the recess 33 are in contact and the degree to which the protrusion 34 enters the recess 33 can be varied, the contact portion of the first winding tube 42 and the second winding tube 62 can be increased or decreased.

[0089] A first groove 36 is formed on the side of the protrusion 34. That is, the protrusion 34 has an external thread formed on its outer periphery. A second groove 35 is formed on the side of the recess 33. That is, the recess 33 has an internal thread formed on its inner periphery. The first groove 36 and the second groove 35 are formed in a spiral shape.

[0090] With the protrusion of the first groove 36 in contact with the recess of the second groove 35, and the recess of the first groove 36 in contact with the protrusion of the second groove 35, the protrusion 34 is rotated while being inserted into or pulled out of the recess 33, thereby allowing the distance between the detection coil 3a and the compensation coil 4a along the central axis CB direction to change continuously. Furthermore, the distance between the detection coil 3b and the compensation coil 4a along the central axis CB direction, as well as the distance between the compensation coil 4a and the compensation coil 4b along the central axis CB direction, also changes continuously.

[0091] Alternatively, an adhesive solid material can be adhered to the surfaces of the first groove 36 and the second groove 35. This solid material could be, for example, sealing tape. This improves the positional retention force.

[0092] It can also be configured such that the position of one of the first winding tube 42 and the second winding tube 62 is fixed, while the position of the other can be changed.

[0093] For example, it can be configured such that the position of the first winding tube 42 is fixed while the position of the second winding tube 62 can be varied. In this case, the detection coils 3a and 3b form a moving surface with a low magnetic field strength, such as a linear near-zero magnetic field region FFL.

[0094] As described above, according to this embodiment, by increasing or decreasing the contact portion between the first winding tube 42 and the second winding tube 62, the distance between the detection coil 3a and the compensation coil 4a in the direction of the central axis CB can be varied. Therefore, without having the second winding tube 62 holding the compensation coil 4a contact the winding tube (not shown) of the coils 5a and 5b that hold the alternating magnetic field, the position of the compensation coil 4a relative to the detection coil 3a can be varied.

[0095] The various embodiments described above can be appropriately combined. It should be understood that the embodiments disclosed herein are merely illustrative and not restrictive in all respects. The scope of the invention is not limited to the foregoing description but is shown by the claims and is intended to include all modifications of the same meaning and scope as the claims.

[0096] Explanation of symbols

[0097] 1: Magnetic particle; 2: Object under inspection; 3, 3a, 3b: Detection coil; 4, 4a, 4b: Compensation coil; 5, 5a, 5b: AC magnetic field application coil; 6: DC magnetic field applicator; 10: AC power supply; 11, 11A: AC magnetic field applicator; 12, 12A: Magnetization distribution measuring device; 13, 13A: Measuring device; 21, 42: First winding cylinder; 22, 62: Second winding cylinder; 23, 33: Recess; 24, 34: Protrusion; 25, 35: Second slot; 26, 36: First slot; 31: Detection coil pair; 41: Compensation coil pair; 51: AC magnetic field application coil pair; CA, CB: Central axis; FFL: Linear near-zero magnetic field region.

Claims

1. A magnetic particle imaging apparatus that determines a spatial distribution of magnetic particles within an object under examination in an examination region, wherein, The magnetic particle imaging apparatus includes: an alternating-current magnetic field application coil that generates an alternating-current magnetic field that changes the magnetism of the magnetic particles; a direct-current magnetic field applicator that generates a region having a low magnetic field intensity in a manner that changes the magnetism of the magnetic particles only in an arbitrary region of the object under examination; a detection coil that detects the change in the magnetism of the magnetic particles; a compensation coil that has a common central axis with the detection coil and is connected to the detection coil in an opposite polarity; a first winding cylinder that holds the detection coil; and a second winding cylinder that holds the compensation coil, the magnetic particle imaging apparatus is configured to be able to change the distance in the direction of the central axis of the detection coil and the compensation coil by increasing or decreasing the contact portion of the first winding cylinder and the second winding cylinder.

2. The magnetic particle imaging apparatus according to claim 1, wherein one of the first winding cylinder and the second winding cylinder has a convex portion, the other of the first winding cylinder and the second winding cylinder has a concave portion, the magnetic particle imaging apparatus is configured to be able to change the degree to which the side surface of the convex portion and the side surface of the concave portion are in contact and the degree to which the convex portion enters the concave portion.

3. The magnetic particle imaging apparatus according to claim 2, wherein a first groove is formed in the side surface of the convex portion, and a second groove is formed in the side surface of the concave portion.

4. The magnetic particle imaging apparatus according to claim 3, wherein the first groove and the second groove are formed in a spiral shape.

5. The magnetic particle imaging apparatus according to claim 3 or 4, wherein a solid adhesive is attached to the surface of the first groove and the second groove.

6. The magnetic particle imaging apparatus according to any one of claims 2 to 5, wherein the magnetic particle imaging apparatus is configured to fix the position of one of the first winding cylinder and the second winding cylinder and to be able to change the position of the other.

7. The magnetic particle imaging apparatus according to claim 6, wherein the magnetic particle imaging apparatus is configured to fix the position of the first winding cylinder and to be able to change the position of the second winding cylinder.

8. The magnetic particle imaging apparatus according to claim 7, wherein the detection coil forms a moving surface of the region having a low magnetic field intensity.

9. The magnetic particle imaging apparatus according to any one of claims 1 to 8, wherein the magnetic particle imaging apparatus includes a measurer that outputs a signal representing the difference between the signal measured by the detection coil and the signal measured by the compensation coil.

10. The magnetic particle imaging apparatus according to claim 1, wherein the alternating-current magnetic field application coil includes a first alternating-current magnetic field application coil and a second alternating-current magnetic field application coil, the detection coil includes a first detection coil and a second detection coil connected in series, the compensation coil includes a first compensation coil and a second compensation coil connected in series, and the magnetic particle imaging apparatus is configured to be able to change the distance in the direction of the central axis of the detection coil and the compensation coil by increasing or decreasing the contact portion of the first winding cylinder and the second winding cylinder. The first detection coil, the second detection coil, the first compensation coil, and the second compensation coil have a common central axis, The first detection coil and the second detection coil are arranged so as to sandwich the magnetic particles, The first compensation coil and the second compensation coil are arranged so as to sandwich the magnetic particles, the first detection coil, and the second detection coil, The first AC magnetic field application coil and the second AC magnetic field application coil are arranged so as to sandwich the magnetic particles, the first detection coil, the second detection coil, the first compensation coil, and the second compensation coil, The first winding tube holds the first detection coil, the second detection coil, and the second compensation coil, The second winding tube holds the first compensation coil, The distance in the direction of the central axis of the first detection coil and the first compensation coil is varied by increasing or decreasing the contact portion of the first winding tube and the second winding tube.

11. The magnetic particle imaging apparatus according to claim 10, wherein The magnetic particle imaging apparatus is provided with a measurer that outputs a signal indicating the difference between the signal measured by the first detection coil and the second detection coil and the signal measured by the first compensation coil and the second compensation coil.

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