JP2017064084A - Magnetic resonance imaging apparatus and method of capturing magnetic resonance images - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic resonance imaging apparatus which uses no shield room to improve the operability and achieve flexible adaptability to various subjects, and yet increase the high-frequency electromagnetic shield performance.SOLUTION: The magnetic resonance imaging apparatus captures a magnetic resonance image of a subject W accommodated in a gantry 2 thereof, comprising: a subject accommodation part 22 for accommodating the subject W; a gantry opening 21 for receiving the subject W; a shield box 3 covered with a shield material for shielding high-frequency waves, and arranged inside the subject accommodation part 22; and a high-frequency coil 4 for illuminating the subject W with high-frequency pulses and detecting NMR signals from the subject W. The shield box 3 includes an internal space in which the subject W and high-frequency coil 4 can be accommodated on an easy putting-in/out basis. Magnetic resonance images are captured when the subject W and high-frequency coil 4 are accommodated in the shield box 3.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a magnetic resonance imaging apparatus and a magnetic resonance image imaging method, and more particularly, to a magnetic resonance imaging apparatus for capturing a magnetic resonance image by accommodating a subject and a high-frequency coil in a shield box, and a magnetic resonance image The present invention relates to an imaging method.

  2. Description of the Related Art Conventionally, a small-sized magnetic resonance imaging apparatus that does not require a high-frequency electromagnetic shield room is known for the purpose of imaging an entire subject's hand at once (for example, Patent Document 1).

  In the small magnetic resonance imaging apparatus described in Patent Document 1, a local high-frequency electromagnetic shield is provided in an opening of an RF probe so as to cover the entire hand, which is a test site, and a hand (test site) is placed therein. Put in and image. Then, the high frequency electromagnetic shield room is not required by grounding the local high frequency electromagnetic shield and performing high frequency coupling with the forearm of the subject at the time of imaging.

JP 2009-131462 A (Claim 1, paragraphs 0017 to 0022, FIG. 2)

  However, the small magnetic resonance imaging apparatus described in Patent Document 1 has a problem in that since the local high-frequency electromagnetic shield into which the hand that is the subject is inserted has an opening, high frequency leaks from the opening, so that the shielding performance deteriorates. was there.

  In addition, the small magnetic resonance imaging apparatus described in Patent Document 1 is suitable when the region to be examined is limited. For example, when it is applied to small animals such as dogs and cats having different sizes and shapes, the operability is small. There was a problem of being bad.

  Accordingly, the present invention provides a magnetic resonance imaging apparatus and a magnetic resonance image imaging method capable of improving operability, easily adapting flexibly to a subject such as a small animal, and improving high-frequency electromagnetic shielding properties. Is an issue.

  In order to solve the above-mentioned problems, an invention according to claim 1 is a magnetic resonance imaging apparatus for capturing a magnetic resonance image by accommodating a subject in a gantry in which a gradient magnetic field generating means and a static magnetic field generating means are arranged. A subject accommodating portion for accommodating the subject, a gantry opening for receiving the subject, a shield box disposed in the subject accommodating portion and covered with a shielding material for shielding high frequency, and the subject A high-frequency coil that irradiates a sample with a high-frequency pulse and detects an NMR signal from the subject, and the shield box has an internal space in which the subject and the high-frequency coil can be inserted and removed freely, and the shield The object and the high-frequency coil are accommodated in a box, and a magnetic resonance image is captured.

  In the magnetic resonance imaging apparatus according to the present invention, since the shield box can be easily put in and out of the subject accommodating portion in the gantry from the gantry opening for receiving the subject, the operability is improved.

  In other words, a shield box having an appropriate shape is used so that it can be adapted to various subjects, the subject and the high-frequency coil are accommodated in the shield box, and the shield box is disposed in the subject accommodating portion in the gantry. By imaging the sample, the operability is improved and it can be suitably adapted to various target subjects.

  Further, by accommodating the subject and the high-frequency coil in the shield box and shielding the shield box without providing an open opening, the high-frequency electromagnetic shielding property can be improved. In addition, since a predetermined high-frequency coil can be attached to various subjects at the time of imaging, it can be suitably adapted to a wide variety of subjects.

  In addition, the magnetic resonance imaging apparatus according to the present invention does not need to shield the gantry opening and the entire gantry by covering the shield box containing the subject and the high-frequency coil with a shield material. The range can be saved significantly. For this reason, it is possible to improve shielding performance and reduce the cost by reducing the size of the magnetic resonance imaging apparatus.

  The invention according to claim 2 is the magnetic resonance imaging apparatus according to claim 1, wherein the shield box is a box-like shape that forms a base portion placed on the subject accommodating portion and the internal space A case portion and an opening formed in the case portion for taking in and out the subject, and the opening and the base coil portion are accommodated in the state where the subject and the high-frequency coil are accommodated in the internal space. The inner space is shielded by being blocked by the above.

The magnetic resonance imaging apparatus according to the present invention includes the base portion and the case portion, thereby forming an internal space in which the subject and the high-frequency coil are detachably accommodated in the shield box.
For this reason, the subject can be easily taken in and out, and can be suitably adapted to various subjects.

  The invention according to claim 3 is the magnetic resonance imaging apparatus according to claim 2, wherein the case portion includes a visual recognition window in which a stainless mesh wire mesh is disposed on a side surface portion. To do.

  The magnetic resonance imaging apparatus according to the present invention includes a viewing window having a stainless mesh wire mesh disposed on the side surface thereof, so that the state of the subject can be visually confirmed while ensuring high-frequency shielding. it can.

  The invention according to claim 4 is the magnetic resonance imaging apparatus according to any one of claims 1 to 3, wherein the subject is a small animal.

  The magnetic resonance imaging apparatus according to the present invention can easily take in and out various small animals having different sizes and body shapes by having the shield box. In addition, since a predetermined high-frequency coil can be attached to various subjects at the time of imaging, it can be suitably adapted particularly to small animals.

  The invention according to claim 5 is an imaging method of a magnetic resonance image in which a subject is accommodated and imaged in a subject accommodating portion in a gantry in which a static magnetic field generating means and a gradient magnetic field generating means are arranged, The gantry includes a gantry opening that receives the subject, a shield box that is disposed in the subject accommodating portion and is covered with a shielding material that shields high frequencies, and irradiates the subject with a high-frequency pulse from the subject. A high-frequency coil for detecting an NMR signal, wherein the subject and the high-frequency coil are accommodated in the shield box and a magnetic resonance image is taken.

  In the magnetic resonance image capturing method according to the present invention, the subject and the high-frequency coil are accommodated in the shield box and a magnetic resonance image is captured, thereby ensuring various high-frequency shielding properties and different body shapes. The small animals can be easily taken in and out, and can be suitably adapted to the small animals.

  The present invention can provide a magnetic resonance imaging apparatus and a magnetic resonance image imaging method that can easily be flexibly adapted to various subjects while achieving miniaturization and can ensure high-frequency electromagnetic shielding properties.

1 is a front view showing an overall configuration of a magnetic resonance imaging apparatus according to an embodiment of the present invention. It is a front sectional view showing the composition of the gantry concerning the embodiment of the present invention. It is a perspective view which shows the shield box which concerns on embodiment of this invention. It is a front view which shows the shielding material which concerns on embodiment of this invention, (a) is a mesh-shaped shielding material, (b) is a punching metal-like shielding material, (c) shows a slit-like gantry main body shielding material. . It is front sectional drawing of the gantry which shows the 1st operation | movement of the magnetic resonance imaging apparatus which concerns on embodiment of this invention, (a) is the state which has arrange | positioned the base part of the shield box in the subject accommodating part, (b) is A state in which a high-frequency coil is attached to the subject on the base portion, and FIG. It is front sectional drawing of the gantry which shows 2nd operation | movement of the magnetic resonance imaging apparatus which concerns on embodiment of this invention, (a) is the state which has arrange | positioned the base part of the shield box in the subject accommodating part, (b) is A state in which a high-frequency coil is attached to the subject on the base portion, and FIG. FIG. 4 is a plan view (upper stage) and a front view (lower stage) showing various forms of the shield box according to the embodiment of the present invention, respectively, (a) is an arc shape that follows the shape of the opening of the gantry, and (b). Is a rectangular parallelepiped type of this embodiment, and (c) is an egg-shaped shield box.

The magnetic resonance imaging apparatus 1 according to the embodiment of the present invention will be described in detail with reference to the drawings as appropriate, taking as an example the case where the subject W is a small animal such as a dog or a cat.
As shown in FIGS. 1 and 2, the magnetic resonance imaging apparatus 1 is arranged in a gantry 2 having a subject container 21, a shield box 3 attached to the subject container 21, and the shield box 3. High-frequency coil 4, control unit 12 that controls the operation of the gantry 2, a computer 13 that sets an imaging condition and reconstructs a magnetic resonance image, and a monitor that displays an imaging condition setting operation screen display and a magnetic resonance image 14.

  Note that the gantry 2 shown in FIGS. 1 and 2 shows only the main components necessary for the explanation in a simplified manner for the sake of convenience of explanation, and the illustration of equipment attached to the cover member and the like is omitted.

  The magnetic resonance imaging apparatus 1 sets the subject W on the high frequency coil 4, accommodates the subject W and the high frequency coil 4 in the shield box 3, and captures a magnetic resonance image.

  As shown in FIG. 2, the gantry 2 includes a gantry opening 21 for inserting and removing the shield box 3, gradient magnetic field generating coils 23 and 23 as gradient magnetic field generating means, and a static magnetic field generating magnet as static magnetic field generating means. 24.

  The gradient magnetic field generating coils 23 and 23 are connected to the control unit 12 (see FIG. 1) by power cables 23b and 23b via noise filters 23a and 23a.

The high-frequency coil 4 irradiates the subject W with a high-frequency pulse and detects a weak NMR (Nuclear Magnetic Resonance) signal from the subject W.
The high frequency coil 4 is connected to the control unit 12 through a noise filter 41 through a high frequency pulse irradiation cable 42 and a high frequency signal detection cable 43 that receives a weak NMR signal (nuclear magnetic resonance signal). The high-frequency signal detection cable 43 is provided with a preamplifier 44 that amplifies a weak NMR signal.

  The high-frequency coil 4 can be configured in various forms so that it can be easily attached to the subject W according to the shape of the subject W or the like. As an example, the high-frequency coil 4 has a cylindrical shape or a cylindrical shape. There is a structure that can be assembled and separated by vertically splitting the cylinder of No. into a half circle.

  The magnetic resonance imaging apparatus 1 amplifies weak NMR detected from the subject W by the high-frequency coil 4 by the preamplifier 44, further amplifies and AD converts it by the control unit 12, and then sends the data to the computer 13 (see FIG. 1). Forward. The computer 13 performs Fourier transform or the like on the data amplified and AD converted by the control unit 12 to reconstruct an image of the subject W and display it on the monitor 14.

  As shown in FIG. 1, the magnetic resonance imaging apparatus 1 displays a graphical user interface screen (GUI screen) on the monitor 14 by the computer 13. The computer 13 sends a command to the control unit 12 according to the imaging conditions set by the operator (not shown). The control unit 12 appropriately drives the gradient magnetic field generating coils 23 and 23 and the high-frequency coil 4 in accordance with instructions from the computer 13.

  Specifically, the control unit 12 supplies an output to the gradient magnetic field generation coil 3 via the power cables 23b and 23b by a gradient magnetic field generation power source (not shown) in the control unit 12, thereby generating an appropriate gradient magnetic field. generate. Since noise filters 23a and 23a are attached to the power cables 23b and 23b, noise can be reduced.

  The control unit 12 generates an appropriate high-frequency pulse from the high-frequency coil 4 by supplying an output to the high-frequency coil 4 via a high-frequency pulse irradiation cable 42 by a high-frequency generator (not shown) in the control unit 12. Let Since the noise filter 41 is attached to the high-frequency pulse irradiation cable 42, noise can be reduced.

The gradient magnetic field generating coils 23 and 23 are disposed around the subject accommodating portion 22 so as to sandwich the subject accommodating portion 22 from above and below.
The static magnetic field generating magnet 24 is disposed around the gradient magnetic field generating coils 23 and 23 so as to sandwich the gradient magnetic field generating coils 23 and 23 from above, below, right and left, and rearward. A gantry opening 21 is provided in front of the gantry 2.
The gantry 2 is provided with gradient magnetic field generating coils 23, 23 around the subject container 22, and a static magnetic field generating magnet 24 is arranged around the gradient magnetic field generating coils 23, 23. It is configured to cover with.

  The shield box 3 includes a base portion 31 placed on the subject accommodating portion 22, a box-like case portion 32 that forms an internal space, and an opening portion that is formed in the case portion 32 and allows the subject W to be taken in and out. 33.

The base unit 31 is a member on which the subject W is placed, and includes a plate-like substrate 31a and a copper foil 31b that is a shield material disposed on the lower surface of the substrate 31a.
The case portion 32 includes an upper plate 32a disposed at the top, four side plates 32b disposed around the upper plate 32a, and a copper foil 32c that is a shield material disposed on the upper surface of the upper plate 32a. And a stainless steel mesh wire mesh 32d, which is a shield material disposed to cover the outside of the side plate 32b, and a visual recognition window 32e formed on the side plate 32b.

  In the present embodiment, the copper foil 31b, the copper foil 32c, and the mesh wire net 32d, which are shield materials, are disposed on the outside (upper and lower surfaces and side surfaces) of the shield box 3, but the present invention is not limited to this. It may be arranged inside.

  The opening 33 is greatly opened toward the lower side of the case portion 32. Since the opening 33 can secure a wide opening area, the subject W and the high-frequency coil 4 can be easily put in and out of the shield box 3.

  The viewing window 32e is an opening window for viewing the state of the subject W formed on the side plate 32b. Since the mesh wire net 32d is disposed in the visual recognition window 32e, it has air permeability and can secure high frequency shielding properties.

  In the present embodiment, the shield material is composed of the copper foil 31b, the copper foil 32c, and the stainless steel mesh wire mesh 32d. However, the shield material is not limited to this, and is a metal having high conductivity, which contributes to the magnetic field distribution. A material that has little influence and hardly changes the magnetic field distribution can be preferably used.

  Specifically, as shown in FIG. 4, aluminum, copper, copper fiber, stainless steel or the like is used as the material, and a plate-like panel can be adopted as the form, but the eddy current generated by the magnetic field is suppressed. In order to improve the shielding performance, a mesh-like panel 34a (see FIG. 4 (a)) in which electric conductors are formed in a mesh shape, and a punching metal-like panel 34b (see FIG. 4 (b)) in which many small through holes are formed. An insulating material is provided between the slit-shaped panel 34c and the slit-shaped panel 34c by arranging the slit ST 34c (see FIG. 4C) in which a large number of slits ST are formed and the slits ST of the slit-shaped panel 34c in different directions. A composite panel (not shown) formed by interposition can be employed.

  The shield box 3 has an insertion hole (not shown) for passing an anesthetic gas suction hose and pipe for processing the subject W as appropriate, a signal line of a device for monitoring heartbeat and respiration, and the like. The hose and pipe insertion holes and ventilation holes (not shown) for introducing air and oxygen are formed, but are not particularly limited, and thus detailed description thereof is omitted.

Next, the first operation of the magnetic resonance imaging apparatus 1 according to the embodiment of the present invention configured as described above will be described mainly with reference to FIGS. 2 and 5.
As shown in FIG. 2, the magnetic resonance imaging apparatus 1 arranges the shield box 3 in the subject accommodating portion 22 in the gantry 2 in which the static magnetic field generating magnet 24 and the gradient magnetic field generating coil 23 are arranged, and the shield box. The subject W and the high-frequency coil 4 are accommodated in 3 to take a magnetic resonance image.

  Specifically, as shown in FIG. 5A, the base portion 31 of the shield box 3 is placed on a movable moving table T disposed in front of the gantry opening 21. Then, the subject W is placed on the base unit 31 placed on the moving table T together with the high frequency coil 4 in a state where the high frequency coil 4 is mounted on the subject W.

  In the present embodiment, the moving table T is adopted, but a slide table (not shown) that can be pulled out from the subject accommodating portion 22 may be adopted.

Then, as shown in FIG. 5B, the base portion 31 is configured such that the opening portion 33 of the case portion 32 is closed by the base portion 31 with the subject W and the high-frequency coil 4 placed on the base portion 31. The case part 32 is set in
Then, as shown in FIG. 5C, the shield box 3 is accommodated in the subject accommodating portion 22 in a state where the high frequency coil 4 and the subject W are accommodated in the internal space of the shield box 3.

  In this way, the magnetic resonance imaging apparatus 1 accommodates the high-frequency coil 4 and the subject W in the internal space of the shield box 3, shields the shield box 3 from the outside, and performs high-frequency magnetic shielding. A magnetic resonance image is taken.

  In the present embodiment, the high-frequency coil 5 is mounted on the subject W and placed on the base portion 31. However, the present invention is not limited to this, and the high-frequency coil 4 is disposed on the base portion. The subject W may be attached to 4.

Next, the second operation of the magnetic resonance imaging apparatus 1 will be described with reference mainly to FIGS.
As shown in FIG. 6A, the base portion 31 of the shield box 3 is placed on the subject accommodating portion 22. Then, as shown in FIG. 6B, the subject W is placed on the base portion 31 together with the high-frequency coil 5 with the high-frequency coil 4 mounted on the subject W.

  Then, as shown in FIG. 6C, the base portion 31 is configured such that the opening portion 33 of the case portion 32 is closed by the base portion 31 with the subject W and the high-frequency coil 4 placed on the base portion 31. The case part 32 is set in

  In this way, the magnetic resonance imaging apparatus 1 accommodates the high-frequency coil 4 and the subject W in the internal space of the shield box 3, shields the shield box 3 from the outside, and performs high-frequency magnetic shielding. A magnetic resonance image is taken.

  In the above-described embodiment, the high-frequency coil 5 is mounted on the subject W and placed on the base 31. However, the present invention is not limited to this. The subject W may be attached to the coil 4.

  The magnetic resonance imaging apparatus 1 operating as described above has the following operational effects. That is, the object W and the high-frequency coil 4 are accommodated in the shield box 3 and the shield box 3 is shielded without providing an open opening, so that the high-frequency electromagnetic shielding property can be improved. In addition, since the predetermined high-frequency coil 4 can be attached to various subjects W at the time of imaging, it can be suitably adapted to a wide variety of subjects W.

  In addition, the magnetic resonance imaging apparatus 1 covers the shield box 3 that accommodates the subject W and the high-frequency coil 4 with a shielding material (copper foil 31b, copper foil 32c, and mesh wire mesh 32d, see FIG. 2), thereby gantry. Since the opening 21 and the entire gantry 2 do not need to be shielded, the installation range of the shielding material can be greatly reduced, the shielding performance can be improved, and the magnetic resonance imaging apparatus 1 can be downsized to reduce the cost.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be implemented with appropriate modifications.
For example, in the present embodiment, as shown in FIG. 6B, the shield box 3 has a rectangular box shape, but the present invention is not limited to this. An arc-shaped shield box 3A following the shape of the gantry opening as shown in FIG. 6A and an egg-shaped shield box 3B as shown in FIG.

  In the present embodiment, the opening 33 of the shield box 3 is formed so as to open toward the lower side of the case part 32. However, the opening opens toward the upper side of the case part 32, and the base part 31 is replaced with a lid. The case portion 32 may be shielded by the body, or an opening / closing door may be provided at the opening 33 of the case portion 32. In short, the structure is such that the subject W can be accommodated and shielded in the shield box 3. For example, it can be appropriately modified according to the shape of the subject W.

  Further, in the present embodiment, the case where the subject W is a small animal has been described. However, the present invention is not limited to this, and can be imaged as long as it is a group of objects containing moisture, such as vegetables and trees. It can also be applied to other plants and fruits.

DESCRIPTION OF SYMBOLS 1 Magnetic resonance imaging apparatus 2 Gantry 3, 3A, 3B Shield box 4 High frequency coil 12 Control unit 13 Computer 14 Monitor 21 Gantry opening part 22 Subject accommodating part 23 Gradient magnetic field generation coil 23a Noise filter 23b Power cable 24 Static magnetic field generation magnet 31 Base part 31a Substrate 31b Copper foil (shield material)
32 Case part 32a Upper plate 32b Side plate 32c Copper foil (shield material)
32d mesh wire mesh (shield material)
32e Viewing window 33 Opening 34a Mesh panel 34b Punched metal panel 34c Slit panel 41 Noise filter 42 High frequency pulse irradiation cable 43 High frequency signal detection cable 44 Preamplifier W Subject ST Slit

Claims (5)

A magnetic resonance imaging apparatus for capturing a magnetic resonance image by accommodating a subject in a gantry in which a gradient magnetic field generating means and a static magnetic field generating means are arranged,
A subject storage section for storing the subject;
A gantry opening for receiving the subject;
A shield box disposed in the subject container and covered with a shield material that shields high frequency;
A high-frequency coil that irradiates the subject with a high-frequency pulse and detects an NMR signal from the subject, and
The shield box has an internal space in which the subject and the high-frequency coil can be freely inserted and removed,
Accommodating the subject and the high-frequency coil in the shield box to capture a magnetic resonance image;
A magnetic resonance imaging apparatus. The shield box is
A base placed on the subject container;
A box-shaped case portion forming the internal space;
An opening formed in the case portion for taking in and out the subject,
In a state where the subject and the high-frequency coil are accommodated in the internal space, the opening is closed by the base portion to shield the internal space;
The magnetic resonance imaging apparatus according to claim 1. The case portion has a visual window in which a stainless steel mesh wire mesh is disposed on a side surface portion;
The magnetic resonance imaging apparatus according to claim 2. The subject is a small animal, plant, and fruit that can be housed in a shield box in the gantry,
The magnetic resonance imaging apparatus according to claim 1, wherein the magnetic resonance imaging apparatus is a magnetic resonance imaging apparatus. A magnetic resonance image imaging method for accommodating and imaging a subject in a subject accommodating portion in a gantry in which a static magnetic field generating means and a gradient magnetic field generating means are arranged,
The gantry is
A gantry opening for receiving the subject;
A shield box disposed in the subject container and covered with a shield material that shields high frequency;
A high-frequency coil that irradiates the subject with a high-frequency pulse and detects an NMR signal from the subject, and
Accommodating the subject and the high-frequency coil in the shield box to capture a magnetic resonance image;
A method of imaging a magnetic resonance image characterized by the above.

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