JP2013158429A - Resonance signal amplification probe and high-frequency treatment instrument for endoscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resonance signal amplification probe capable of adjusting resonance frequency to Larmor frequency, and to provide a high-frequency treatment instrument for endoscopes.SOLUTION: A resonance signal amplification probe that is inserted in a body cavity and amplifies a resonance signal, when capturing an image using a magnetic resonance spectroscopy, includes: a flexible sheath; an operation wire that is inserted in the interior of the flexible sheath; a loop-shaped resonant circuit that can project/retract with respect to the distal end of the flexible sheath; a connecting member for connecting the distal end of the operation wire to the resonant circuit; and an operating section that advances/retracts the operation wire in the interior of the flexible sheath to advance/retract the resonant circuit. The resonant circuit has a loop-shaped resonance coil electromagnetically coupled with a receiving coil that receives a resonance signal when capturing an image using a magnetic resonance spectroscopy, and a capacitor inserted inside the loop of the resonance coil and serially connected to the resonance coil. The loop diameter of the resonance coil changes with the advance/retraction of the resonant circuit.

Description

  The present invention relates to magnetic resonance imaging (MRI), electron spin resonance imaging (ESRI), etc. (in this specification, MRI, ESRI, etc. are collectively referred to as “magnetic resonance spectroscopy”). In particular, the present invention relates to a resonance signal amplification probe that is inserted into a body cavity and amplifies a resonance signal, and a high-frequency treatment instrument for an endoscope.

  Conventionally, magnetic resonance imaging (MRI) has been widely used to create an image of the inside of a human body. MRI magnetically excites the nuclear spin of a subject placed in a static magnetic field with a radio frequency (RF) signal of Larmor frequency, and generates nuclear magnetic resonance (NMR) generated by this excitation. This is an imaging method for reconstructing an image from a signal. In MRI, an RF coil for RF excitation (that is, a transmission coil) and an RF coil for receiving NMR signals (that is, a reception coil) are configured as separate coils, respectively, and the reception coil is brought close to the object to be imaged to obtain an NMR signal. The signal-to-noise ratio of the received signal is increased.

  In recent years, electron spin resonance imaging (ESRI) has also been used in which free radicals (free radicals), which are intermediate products of redox metabolism, are detected non-destructively and selectively (for example, Patent Document 1). ESRI is one of the magnetic resonance spectroscopy methods based on the same principle as MRI, and by using the same configuration as MRI, unpaired electrons of a subject placed in a static magnetic field can be magnetically expressed by a high frequency signal of Larmor frequency. This is an imaging method in which an image is reconstructed from an electron spin resonance (ESR) signal that is excited and generated along with this excitation.

  In recent years, a system has been developed in which an MRI or ESRI system and an endoscope apparatus are combined to perform diagnosis and treatment while observing an NMR image or an ESR image and an endoscope image. According to such a system, when an abnormal location (observation target site) is visually found by an endoscopic image, it can be confirmed by NMR image or ESR image whether the abnormal location is malignant. Useful in terms. Therefore, in such a system, in order to efficiently receive the NMR signal or ESR signal from the observation target site specified by the endoscopic image (that is, to increase the resolution of the NMR image or ESR image), The receiving coil is disposed in the body cavity of the subject (for example, Patent Document 2).

  Further, in order to efficiently receive the NMR signal or ESR signal from such an observation target region, a resonance coil that is electromagnetically coupled to the receiving coil is disposed so as to surround the observation target region, A configuration for amplifying and receiving an NMR signal or an ESR signal from the above has also been studied (for example, Patent Document 3).

Special table 2011-527222 gazette Japanese Patent Laid-Open No. 9-294704 JP 2005-535385 gazette

  The resonance coil of Patent Document 3 forms a capacitor by sandwiching a dielectric material between both ends of a resonance coil (loop coil), and constitutes a so-called LC resonance circuit. In order to amplify the NMR signal using the resonance coil, it is necessary to match the resonance frequency of the LC resonance circuit to the Larmor frequency. Therefore, by sliding both ends of the resonance coil with respect to the dielectric material, The capacitance is changed, and the resonance frequency of the LC resonance circuit is adjusted to be the Larmor frequency.

  However, in such a configuration, a slight gap is formed between the end portion of the resonance coil and the dielectric material, and there is a problem that body fluid enters the gap. When body fluid enters between the end of the resonance coil and the dielectric material, the capacitance of the capacitor changes, which causes a problem that the resonance frequency of the LC resonance circuit cannot be maintained at the Larmor frequency.

  The present invention has been made to solve the above problems. That is, the present invention provides a resonance signal amplifying probe and a high frequency for an endoscope provided with a resonance coil capable of adjusting the resonance frequency of the LC resonance circuit to the Larmor frequency while maintaining the frequency stably. It aims at providing a treatment tool.

  In order to achieve the above object, the resonance signal amplification probe of the present invention is a resonance signal amplification probe that is inserted into a body cavity and amplifies a resonance signal at the time of imaging using magnetic resonance spectroscopy. A flexible sheath, an operation wire inserted into the flexible sheath, a loop-shaped resonance circuit that can project and retract from the distal end of the flexible sheath, and a connection that connects the distal end portion of the operation wire and the resonance circuit A member and an operation unit that advances and retracts the resonance circuit by advancing and retreating the operation wire in the flexible sheath, and the resonance circuit includes a receiving coil that receives a resonance signal at the time of imaging using magnetic resonance spectroscopy. An electromagnetically coupled loop-shaped resonant coil and a capacitor inserted in the loop of the resonant coil and connected in series with the resonant coil, the loop diameter of the resonant coil changes according to the advance / retreat of the resonant circuit This The features.

  According to such a configuration, it is possible to adjust the resonance frequency of the resonance circuit by changing the loop diameter of the resonance coil by operating the operation unit. Therefore, the resonance frequency of the resonance circuit can be adjusted to the Larmor frequency for imaging using magnetic resonance spectroscopy. In addition, since the capacitance of the capacitor can be fixed, the resonance frequency of the LC resonance circuit can be stably maintained.

  The loop diameter of the resonance coil is desirably adjusted so that the resonance frequency of the resonance circuit substantially matches the Larmor frequency of imaging using magnetic resonance spectroscopy. As described above, when the resonance frequency of the resonance circuit is substantially matched to the Larmor frequency, the resonance signal detected by the resonance coil becomes maximum, and the resonance signal from the region surrounded by the resonance coil can be received efficiently.

  The resonance coil can be formed of a single-layer air-core coil obtained by annularly deforming a nonmagnetic metal wire. In this case, it is desirable that the surface of the metal wire is covered with a tube member. According to such a configuration, the use of the resonance signal amplification probe does not damage the mucous membrane in the body cavity, and it is possible to reduce the change in parasitic capacitance that occurs when the resonance coil contacts the mucosa. .

  Further, the capacitor can be disposed in a position of the resonance coil loop facing the connecting member.

  Moreover, the contact part which can connect the high frequency power supply for sending a high frequency current to a resonance coil via an operation wire can be provided. According to such a configuration, a high frequency current can be applied to the resonance coil, and a lesioned part or the like can be excised.

  Further, the capacitor can be arranged in a position close to the connecting member in the loop of the resonance coil. In this case, it is desirable that the capacitor is housed inside the connecting member.

  Moreover, it is desirable that the resonance coil has a fold at a position facing the connecting member.

  The capacitor can be formed of a ceramic capacitor whose capacitance can be changed.

  The flexible sheath is preferably inserted into the body cavity via the treatment instrument insertion channel of the electronic endoscope.

  The imaging using magnetic resonance spectroscopy is electron spin resonance imaging, and the resonance signal can be an electron spin resonance signal.

  From another viewpoint, the high-frequency treatment instrument for an endoscope of the present invention is an endoscope that is inserted into a body cavity through a treatment instrument insertion channel of the endoscope at the time of imaging using magnetic resonance spectroscopy. A high-frequency treatment instrument for use with a flexible sheath, an operation wire inserted into the flexible sheath, a loop-shaped knife portion that can project and retract from the distal end of the flexible sheath, and the distal end of the operation wire A connecting member for connecting the knife portion and the knife portion, an operation portion for moving the knife portion forward and backward in the flexible sheath, and a high-frequency power source for supplying a high-frequency current to the knife portion via the operation wire The knife portion is connected to a receiving coil that receives a resonance signal during imaging using magnetic resonance spectroscopy, and a loop-shaped resonance coil portion that is electromagnetically coupled to the receiving coil. Inserted in the loop of the And a capacitor connected in series with section, the loop diameter of the resonance coil unit may vary in accordance with the reciprocating knife portion.

  As described above, according to the present invention, it is possible to adjust the resonance frequency of the LC resonance circuit to the Larmor frequency, while maintaining the frequency stably, and the high frequency for the endoscope A treatment tool is provided.

FIG. 1 is a block diagram of an electron spin resonance imaging (ESRI) system in which an ESR signal amplification probe according to a first embodiment of the present invention is used. 2A and 2B are an external view and a cross-sectional view showing the configuration of the ESR signal amplification probe according to the first embodiment of the present invention. FIG. 3 is an enlarged view for explaining the configuration near the tip of the ESR signal amplification probe according to the first embodiment of the present invention. FIG. 4 is an equivalent circuit diagram showing the relationship between the resonance circuit of the ESR signal amplification probe according to the first embodiment of the present invention and the RF receiving coil of the ESRI apparatus. FIG. 5 is a diagram showing a modification of the ESR signal amplification probe according to the first embodiment of the present invention. 6A and 6B are an external view and a cross-sectional view showing the configuration of an ESR signal amplification probe according to the second embodiment of the present invention. FIG. 7 is a diagram for explaining the operation of the ESR signal amplification probe according to the second embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<First Embodiment>
FIG. 1 is a block diagram of an electron spin resonance imaging (ESRI) system in which an ESR signal amplification probe (resonance signal amplification probe) according to the first embodiment of the present invention is used. As shown in FIG. 1, the ESRI system 10 includes an ESRI apparatus 100, an endoscope apparatus 200, and an ESR signal amplification probe 300 (hereinafter referred to as “probe 300”). And a system capable of diagnosing and treating while observing an endoscope image by the endoscope apparatus 200.

  The ESRI apparatus 100 obtains a tomographic image (ESR image) of the imaging target 20 using the ESR phenomenon, and includes a static magnetic field generating magnet 102, a gradient magnetic field coil 104, an RF transmission coil 106, an RF reception coil 110, and an RF drive. Unit 120, data collection unit 130, gradient magnetic field generation unit 140, data processing unit 160, display unit 170, cradle 180, and control unit 150 that comprehensively controls them. The imaging target 20 (examinee) is loaded into the ESRI apparatus 100 by being mounted on the cradle 180 and by a conveying means (not shown).

  The static magnetic field generating magnets 102 are a pair of magnets (for example, permanent magnets) facing each other with the imaging target 20 interposed therebetween, and form a strong and uniform vertical static magnetic field around the imaging target 20.

  The gradient magnetic field coils 104 are a pair of coils facing each other with the imaging target 20 interposed therebetween, and generate a gradient magnetic field for giving a gradient (gradient) to the static magnetic field intensity. A gradient magnetic field generation unit 140 is connected to the gradient magnetic field coil 104, and a drive signal from the gradient magnetic field generation unit 140 is applied to the gradient magnetic field coil 104 to generate a gradient magnetic field. There are three types of gradient magnetic field generated: slice gradient magnetic field, readout gradient magnetic field, and phase encode gradient magnetic field. Corresponding to these three types of gradient magnetic field, gradient magnetic field coil 104 includes three types of gradient coils (not shown). Have. The tomographic plane in the imaging target 20 can be set by appropriately changing the drive signal output from the gradient magnetic field generator 140 to the gradient magnetic field coil 104 and changing the method of applying the gradient magnetic field.

  The RF transmission coil 106 transmits an RF excitation signal for exciting spins in the body of the imaging target 20 to the static magnetic field space. An RF drive unit 120 is connected to the RF transmission coil 106, and a drive signal from the RF drive unit 120 is given to the RF transmission coil unit 106 to transmit an RF excitation signal. In the present embodiment, the static magnetic field strength of the ESRI apparatus 100 is 10 millitesla, and the frequency of the RF excitation signal (that is, the Larmor frequency) is about 300 MHz.

  The RF receiving coil 110 receives an electron spin resonance (ESR) signal in which a spin excited by an RF excitation signal is generated. The RF receiving coil 110 is, for example, a cylindrical coil that surrounds the entire imaging target 20, and has sensitivity to the entire imaging target 20 surrounded by the coil or a specific region of the imaging target 20. Although details will be described later, in the present embodiment, in order to efficiently receive the ESR signal from the observation target region specified by the endoscopic image (that is, the resolution of the ESR image of the observation target region is improved). For this reason, a resonance coil that electromagnetically couples with the RF receiving coil 110 is arranged around the site to be observed to amplify the ESR signal.

  A data collecting unit 130 is connected to the RF receiving coil unit 110. The data collecting unit 130 takes in a reception signal received by the RF receiving coil unit 110 and collects it as digital data.

  The data processing unit 160 stores the data fetched from the data collection unit 130 in a memory (not shown), and reconstructs the image of the subject 20 by performing two-dimensional inverse Fourier transform on these data.

  A display unit 170 is connected to the data processing unit 160, and the display unit 170 displays a reconstructed image (that is, an ESR image) output from the data processing unit 160 and various types of information.

  As described above, the ESRI apparatus 100 magnetically excites the spin in the body of the imaging target 20 placed in the static magnetic field with the RF excitation signal, and reconstructs an image from the ESR signal generated along with this excitation. A tomographic image (ESR image) is displayed.

  The endoscope apparatus 200 includes an electronic endoscope 201, an endoscope processor 202, and a monitor 203. The electronic endoscope 201 has an image sensor (not shown) at the tip thereof, and outputs a video signal generated by the image sensor to the endoscope processor 202. The endoscope processor 202 performs image processing (for example, color correction, contour enhancement, etc.) on the video signal received from the electronic endoscope 201, and outputs it to the monitor 203.

  When using the ESRI system 10 of the present embodiment, the distal end portion of the electronic endoscope 201 is inserted into the body cavity of the imaging target 20 by the operation of the operator (user), and the operator pays attention to the monitor 203. An image (endoscopic image) of the site to be observed is displayed. Therefore, according to the ESRI system 10 of the present embodiment, the imaging target 20 can be diagnosed while simultaneously observing the ESR image by the ESRI apparatus 100 and the endoscope image by the endoscope apparatus 200. That is, for example, when an abnormal location is visually found by an endoscopic image, whether or not the abnormal location is malignant can be confirmed by the ESR image. Here, in such a system, diagnosis or the like is performed using an ESR image of a relatively narrow region (observation target region), so that an ESR signal from the observation target region is efficiently received and an ESR image with high resolution is obtained. Is required to provide. Therefore, in the present embodiment, the problem is solved by inserting the probe 300 capable of amplifying the ESR signal of the site to be observed from the treatment instrument insertion channel of the electronic endoscope 201.

  As shown in FIG. 1, a probe 300 is inserted through a treatment instrument insertion channel (not shown) of the electronic endoscope 201. The probe 300 includes a resonance coil 310 that electromagnetically couples with the RF reception coil 110 at the tip thereof, and amplifies the ESR signal of the site to be observed and transmits the amplified ESR signal to the RF reception coil 110 (for details). Later).

  2A and 2B are an external view (FIG. 2A) and a cross-sectional view (FIG. 2B) of the probe 300 according to the first embodiment of the present invention. The probe 300 includes a resonance circuit 310, a wire 313 connected to the resonance circuit 310, a sheath 315 through which the resonance circuit 310 and the wire 313 are inserted, an operation unit 320 for operating the wire 313 and the sheath 315, and the like. At the time of diagnosis and treatment using the ESRI system 10, the sheath 315 is inserted into the body cavity from the treatment instrument insertion channel of the electronic endoscope 201 and used.

  FIG. 3 is an enlarged view for explaining the configuration near the tip of the probe 300. 3A is an enlarged cross-sectional view when the resonance circuit 310 protrudes from the distal end portion of the sheath 315, and FIG. 3C is a view when the resonance circuit 310 moves to the operation unit 320 side (ie, retreats). 3 (b) is an enlarged cross-sectional view, and FIG. 3 (b) is an enlarged cross-sectional view showing the state of the resonance circuit 310 in the middle between FIG. 3 (a) and FIG. 3 (c).

  As shown in FIGS. 2 and 3, the resonance circuit 310 of the present embodiment includes a resonance coil 310a formed by deforming two wires in a loop shape, and a capacitor 310b (for example, a ceramic capacitor). Yes. The tips of the two wires constituting the resonance coil 310a are electrically connected to the two electrodes of the capacitor 310b, respectively. Further, the proximal end portions of the two wires constituting the resonance coil 310 a are bundled and mechanically fixed to the distal end portion of the wire 313 by the connecting member 314. In other words, the resonance coil 310a is a single-layer air-core coil composed of two wires, and the resonance coil 310a and the capacitor 310b are connected in series to form a closed circuit, thereby forming a so-called LC resonance circuit. ing. Then, at the time of diagnosis and treatment using the ESRI system 10, the resonance frequency of the resonance circuit 310 is tuned to the Larmor frequency.

  FIG. 4 is an equivalent circuit diagram showing the relationship between the resonance circuit 310 and the RF receiving coil 110. When the resonance circuit 310 arranged in the body cavity of the imaging target 20 is tuned to the Larmor frequency during diagnosis and treatment using the ESRI system 10, the resonance circuit 310 is surrounded by a loop of the resonance circuit 310. An ESR signal from a region (that is, an observation target part) is received. Since the received ESR signal generates a magnetic field in the resonance circuit 310, the magnetic field is detected by the RF receiving coil 110 of the ESRI apparatus 100. That is, the resonance coil 310a of the resonance circuit 310 tuned to the Larmor frequency is coupled (coupled) with the RF reception coil 110 by the mutual induction M, and the magnetic energy generated in the resonance coil 310a is detected by the RF reception coil 110. (FIG. 4). For this reason, when the observation target part is surrounded by the loop of the resonance circuit 310, only the ESR signal from the observation target part is emphasized (that is, amplified), and an ESR image of the observation target part with high resolution can be obtained. it can. Therefore, in the probe 300 of this embodiment, the resonance frequency of the resonance circuit 310 is tuned to the Larmor frequency by changing the loop diameter of the resonance coil 310a.

  The resonance frequency f of the resonance circuit 310 is expressed by the following equation (Equation 1), where L is the inductance of the resonance coil 310a and C is the capacitance of the capacitor 310b.

ここで、ａは共振コイル３１０ａの長さ、ｄは共振コイル３１０ａの内径、ｎは単位長さ当たりの巻き数、ｋは長岡係数である。なお、本実施形態においては、共振周波数ｆを３００ＭＨｚ、コンデンサ３１０ｂの静電容量Ｃを６ｐＦとし、共振コイル３１０ａのインダクタンスＬを４６．９ｎＨと設定した（数１）。なお、共振コイル３１０ａのインダクタンスＬが４６．９ｎＨとなるとき、共振コイル３１０ａの内径ｄは、１９．３５ｍｍとなるため（数２）、本実施形態においては、共振コイル３１０ａのループ径を少なくとも１５ｍｍ〜２５ｍｍの範囲内、より好ましくは１０ｍｍ〜３０ｍｍの範囲内で可変できるように構成している。 Further, the inductance L of the resonance coil 310a is expressed by the following equation (Equation 2).

Here, a is the length of the resonance coil 310a, d is the inner diameter of the resonance coil 310a, n is the number of turns per unit length, and k is the Nagaoka coefficient. In this embodiment, the resonance frequency f is set to 300 MHz, the capacitance C of the capacitor 310b is set to 6 pF, and the inductance L of the resonance coil 310a is set to 46.9 nH (Equation 1). When the inductance L of the resonance coil 310a is 46.9 nH, the inner diameter d of the resonance coil 310a is 19.35 mm (Equation 2). Therefore, in this embodiment, the loop diameter of the resonance coil 310a is at least 15 mm. It is configured to be variable within a range of ˜25 mm, more preferably within a range of 10 mm to 30 mm.

  As apparent from Equations 1 and 2, when the inner diameter (that is, the loop diameter) of the resonance circuit 310 is changed, the inductance L of the resonance coil 310a is changed, so that the resonance frequency f of the resonance circuit 310 can be tuned. Therefore, in the probe 300 according to the present embodiment, the resonance circuit 310 protrudes from the distal end portion of the sheath 315 by operating the operation unit 320, and the resonance coil 310 a The loop diameter is changed (described later). In this specification, the movement of the resonance circuit 310 in the direction protruding from the distal end portion of the sheath 315 is referred to as “advance”, and the movement of the resonance circuit 310 toward the operation unit 320 is referred to as “retraction”. .

  In addition, since the probe 300 of this embodiment is used together with the ESRI apparatus 100 that generates a strong magnetic field, copper, stainless steel, aluminum, or the like, which is a non-magnetic metal, is used for the wire constituting the resonance coil 310a. The surface of the wire constituting the resonance coil 310a may be coated with an insulating film, or may be coated with a tube or the like. According to such a configuration, there is no possibility of damaging the mucous membrane in the body cavity, and since it is insulated from the mucous membrane, a change in parasitic capacitance caused by the resonance coil coming into contact with the mucosa is reduced.

  The wire 313 is made of a nonmagnetic metal such as stainless steel, and is inserted through the sheath 315 in a state of being fixed integrally with the resonance circuit 310 by the connection member 314. The proximal end portion of the wire 313 extends to the operation unit 320. The connection member 314 is a cylindrical non-magnetic metal member having an outer diameter smaller than the inner diameter of the sheath 315. A through hole extending along the extending direction of the wire 313 is formed at the center of the connecting member 314. The diameter of the through hole is the outer diameter and the wire when the two wires constituting the resonance coil 310a are bundled together. It is slightly larger than the outer diameter of 313. The proximal end portion of the two wires and the wire 313 constituting the resonance coil 310a are inserted from the distal end side and the proximal end side of the through hole, respectively, and then fixed to the connection member 314 by brazing, laser welding, or the like.

  The sheath 315 is a flexible tubular member made of a resin such as PTFE (polytetrafluoroethylene). A marker 316 is provided on the outer circumferential surface of the distal end portion of the sheath 315 in the circumferential direction so that the degree of the probe 300 entering the body cavity can be easily recognized by the endoscope apparatus 200. Further, the outer peripheral end portion (edge portion) of the distal end portion of the sheath 315 is chamfered so as not to damage the mucous membrane in the body cavity when the probe 300 is put in and out.

  The operation unit 320 includes a main body 322 to which the sheath 315 is fixed, and a slider 324 to which the proximal end of the wire 313 is fixed (FIG. 2). The main body 322 is a substantially rod-like member, and a guide groove 322a for sliding the slider 324 is extended in the axial direction. On the base end side of the main body 322, a ring 322b for hooking a finger at the time of operation is provided. On the front end side of the main body 322, a sheath tube 315 for guiding the sheath 315 and preventing the folding is provided. ing.

  The slider 324 includes a cylindrical portion 324a that surrounds the outer periphery of the main body 322, and a handle 324b on which a finger is hung during operation. The proximal end portion of the wire 313 is connected and fixed to the slider 324 with a screw (not shown) inside the cylindrical portion 324a. That is, the slider 324 and the wire 313 are mounted on the main body 322 so as to be slidable in the longitudinal direction of the wire 313 along the guide groove 322a. Therefore, when the operator moves the slider 324 of the probe 300 to the ring 322b side (that is, pulls it toward the hand side), the resonance circuit 310 moves backward, and the slider 324 of the probe 300 moves to the distal end side of the sheath 315 ( That is, the resonance circuit 310 moves forward.

  As shown in FIG. 3A, when the resonance circuit 310 is advanced by operating the slider 324, the entire resonance circuit 310 including the resonance coil 310a and the capacitor 310b is exposed (protruded) from the distal end portion of the sheath 315 (see FIG. 3A). Hereinafter, the position of the tip of the resonance circuit 310 when the entire resonance circuit 310 is exposed is referred to as an “exposed position”). As described above, since the resonance coil 310a of the resonance circuit 310 is configured by deforming two wires in a loop shape, a circumference corresponding to the length of the two wires is formed at the exposed position. It becomes the substantially annular coil which has. On the other hand, as shown in FIG. 3C, when the slider 324 is operated to retract the resonance circuit 310, the entire resonance circuit 310 including the resonance coil 310a and the capacitor 310b is accommodated in the distal end portion of the sheath 315 ( Hereinafter, the position of the tip of the resonance circuit 310 when the entire resonance circuit 310 is stored is referred to as a “storage position”). Further, as shown in FIG. 3B, in the middle of FIG. 3A and FIG. 3C (that is, the middle position between the exposed position of the resonant circuit 310 and the storage position), the resonant coil 310a is placed. The two wires constituting the abutment come into contact with the distal end portion of the sheath 315, and the opening degree (that is, the loop diameter) of the resonance coil 310a is regulated by the opening at the distal end portion of the sheath 315. Therefore, the resonance coil 310a of the resonance circuit 310 is a substantially annular coil having a circumference corresponding to the length of two wires protruding from the distal end portion of the sheath 315 (that is, the protruding amount).

  As described above, in the probe 300 of the present embodiment, the resonance circuit 310 protrudes from the distal end portion of the sheath 315 by operating the slider 324, and the loop diameter of the resonance coil 310a is increased according to the protrusion amount of the resonance circuit 310. It is configured to change. Therefore, since the inductance L of the resonance coil 310a changes according to the protrusion amount of the resonance circuit 310, that is, the operation amount of the slider 324, the resonance frequency of the resonance circuit 310 can be tuned.

  The above is the description of the first embodiment of the present invention, but the present invention is not limited to the above-described configuration, and various modifications are possible within the scope of the technical idea of the invention. For example, in the first embodiment, the capacitor 310b is a ceramic capacitor having a fixed capacitance, but is not limited to this configuration. Since the thickness of the mucous membrane, the amount of moisture, and the like differ depending on the part, it is conceivable that the resonance frequency of the resonance circuit 310 slightly changes depending on the part. Therefore, before inserting the probe 300 into the treatment instrument insertion channel of the electronic endoscope 201, for example, a ceramic trimmer capacitor whose capacitance can be varied is used so that the resonance frequency can be shifted according to the site. Also good.

  Further, in the first embodiment, the capacitor 310b is disposed at the distal end portion of the two wires constituting the resonance coil 310a. However, the capacitor 310b may be disposed at the proximal end portion of the two wires. In this case, the resonance coil 310a may be configured by deforming one wire into a loop shape. FIG. 5 is an enlarged cross-sectional view showing a configuration in which a capacitor 310b ′ is disposed at both ends of one wire constituting the resonance coil 310a ′. As shown in FIG. 5, in this modification, the resonance coil 310a ′ is configured by deforming one wire in a loop shape, and both ends of the wire are respectively connected to two electrodes of the capacitor 310b ′. Electrically connected. Then, both ends of the wire are mechanically fixed to the tip of the wire 313 by the connecting member 314 ′ together with the capacitor 310b ′. Note that the connection member 314 ′ of the present modification is formed of an insulating material so that the two electrodes of the capacitor 310 b ′ are not short-circuited. Further, in order to improve the accommodation when the resonance circuit 310 ′ is housed in the distal end portion of the sheath 315, one wire constituting the resonance coil 310 a ′ is on the distal end side (side facing the capacitor 310 b ′). Are provided with creases (creases). According to the configuration of the present modification, the resonance coil 310a ′ is closer to a circle compared to the first embodiment, so that its inductance substantially matches that shown in Equation 2.

  In the first embodiment, the configuration in which the probe 300 is applied to an electron spin resonance imaging (ESRI) system has been described. However, the configuration is not limited to this configuration, and the probe 300 is not limited to magnetic resonance imaging (MRI). It is also possible to apply to a system using). Even when the probe 300 is applied to magnetic resonance imaging (MRI), the probe 300 can be realized with the same configuration as that of electron spin resonance imaging (ESRI), and similar effects can be obtained.

<Second Embodiment>
6A and 6B are an external view (FIG. 6A) and a cross-sectional view (FIG. 6B) of an ESR signal amplification probe 300M (hereinafter referred to as “probe 300M”) according to the second embodiment of the present invention. It is. The probe 300M of the present embodiment is different from the probe 300 of the first embodiment in that the probe 300M is configured to have a function as a snare electrode treatment tool used for body cavity treatment. Hereinafter, differences from the probe 300 of the first embodiment will be described in detail.

  The probe 300M of the present embodiment is configured to be able to supply a high-frequency current for excising a lesion to the resonance circuit 310, and the slider 324M has a plug 326 for connecting to a high-frequency power source (not shown). Is provided. The proximal end portion of the wire 313 is connected and fixed to the plug 326 by a screw 326a inside the cylindrical portion 324a. Accordingly, the high-frequency current supplied from the high-frequency power source is supplied to the resonance circuit 310 via the plug 326, the wire 313, and the connection member 314, all of which are conductive.

  FIG. 7 is a diagram illustrating an operation when the probe 300M is used as a snare electrode treatment tool. As shown in FIG. 7, when the probe 300M is used as a snare electrode treatment instrument, the slider 324M is pushed out so that the loop-shaped resonance circuit 310 is greatly protruded from the sheath 315, and the loop shape of the resonance circuit 310 is expanded. Then, it is hooked on the tissue to be excised (FIG. 7A). Then, by pulling the slider 324M toward the hand side and pulling the resonance circuit 310 into the sheath 315, the loop shape of the resonance circuit 310 is reduced, and the tissue to be excised in the loop of the resonance circuit 310 is tightened (FIG. 7B). )). In this state, a high-frequency current is applied to cauterize the tissue to be excised in the loop of the resonance circuit 310.

  As described above, the probe 300M of the present embodiment can be used as a snare electrode treatment tool (knife) for excising a lesion. Accordingly, when the lesion is identified by the ESRI system 10, the lesion can be immediately excised using the probe 300M. That is, since it is not necessary to change to a new snare electrode treatment instrument, the efficiency of the procedure can be improved.

DESCRIPTION OF SYMBOLS 10 ESRI system 20 Imaging object 100 ESRI apparatus 102 Static magnetic field generation magnet 104 Gradient magnetic field coil 106 RF transmission coil 110 RF reception coil 120 RF drive part 130 Data acquisition part 140 Gradient magnetic field generation part 150 Control part 160 Data processing part 170 Display part 180 Cradle 200 Endoscope device 201 Electronic endoscope 202 Endoscope processor 203 Monitor 300, 300 ', 300M ESR signal amplification probe 310, 310' Resonance circuit 310a, 310a 'Resonance coil 310b, 310b' Capacitor 313 Wire 314 314 ′ Connecting member 315 Sheath 316 Marker 320, 320 M Operation unit 322 Main body 324, 324 M Slider 326 Plug 330 Folding prevention tube

Claims (13)

A resonance signal amplification probe that is inserted into a body cavity at the time of imaging using magnetic resonance spectroscopy and amplifies a resonance signal,
A flexible sheath;
An operation wire inserted into the flexible sheath;
A loop-like resonance circuit capable of protruding and retracting from the tip of the flexible sheath;
A connecting member that connects the tip of the operation wire and the resonance circuit;
An operation unit for moving the resonance circuit forward and backward by moving the operation wire forward and backward in the flexible sheath;
With
The resonant circuit is:
A loop-shaped resonance coil that electromagnetically couples to a reception coil that receives a resonance signal during imaging using the magnetic resonance spectroscopy;
A capacitor inserted in a loop of the resonant coil and connected in series to the resonant coil;
With
The resonance signal amplification probe according to claim 1, wherein a loop diameter of the resonance coil changes in accordance with advancing and retreating of the resonance circuit.   The resonance signal amplification according to claim 1, wherein the loop diameter of the resonance coil is adjusted so that a resonance frequency of the resonance circuit substantially matches a Larmor frequency of imaging using the magnetic resonance spectroscopy. Probe.   The resonance signal amplification probe according to claim 1 or 2, wherein the resonance coil is a single-layer air-core coil obtained by annularly deforming a nonmagnetic metal wire.   4. The resonance signal amplification probe according to claim 3, wherein a surface of the metal wire is covered with a tube member.   5. The probe for amplifying a resonance signal according to claim 1, wherein the capacitor is disposed in a loop of the resonance coil and at a position facing the coupling member. 6. .   6. The resonance signal amplifying device according to claim 1, further comprising a contact portion capable of connecting a high-frequency power source for flowing a high-frequency current to the resonance coil via the operation wire. probe.   5. The resonance signal amplification probe according to claim 1, wherein the capacitor is disposed in a loop of the resonance coil and in a position close to the connection member. 6. .   The resonance signal amplification probe according to claim 7, wherein the capacitor is housed in the connection member.   9. The resonance signal amplifying probe according to claim 7, wherein the resonance coil has a fold at a position facing the connecting member.   The probe for resonance signal amplification according to any one of claims 1 to 9, wherein the capacitor is a ceramic capacitor whose capacitance can be changed.   The probe for resonance signal amplification according to any one of claims 1 to 10, wherein the flexible sheath is inserted into a body cavity via a treatment instrument insertion channel of an electronic endoscope. . Imaging using the magnetic resonance spectroscopy is electron spin resonance imaging,
The resonance signal amplification probe according to any one of claims 1 to 11, wherein the resonance signal is an electron spin resonance signal. An endoscope high-frequency treatment instrument that is inserted into a body cavity via a treatment instrument insertion channel of an endoscope at the time of imaging using magnetic resonance spectroscopy,
A flexible sheath;
An operation wire inserted into the flexible sheath;
A loop-shaped knife portion that can project and retract from the tip of the flexible sheath;
A connecting member that connects the distal end portion of the operation wire and the knife portion;
An operation portion for moving the knife portion forward and backward by moving the operation wire forward and backward in the flexible sheath;
A contact portion that can be connected to a high-frequency power source for flowing a high-frequency current to the knife portion via the operation wire;
With
The knife portion is
A loop-shaped resonance coil unit that electromagnetically couples with a reception coil that receives a resonance signal during imaging using the magnetic resonance spectroscopy;
A capacitor that is inserted into the loop of the resonant coil section and connected in series to the resonant coil section;
With
The high frequency treatment instrument for an endoscope, wherein the loop diameter of the resonance coil portion changes according to the advancement and retreat of the knife portion.

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