JPH0653111B2 - Magnetic resonance imaging equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to magnetic resonance (MR).
The information based on the density distribution of specific nuclear spins in a specific cross section of an object is calculated by using the so-called computer tomography (CT: Comp.
CT image (Computed Tomogram)
The present invention relates to a magnetic resonance imaging apparatus called an MRI apparatus or the like for imaging as a).

[0002]

2. Description of the Related Art For example, in a diagnostic MRI apparatus, in order to obtain a tomographic image at a specific position of a subject, a very uniform static magnetic field Ho along the Z axis direction shown in FIG. And a pair of gradient magnetic field coils 1
A linear magnetic field gradient Gz is added to the static magnetic field Ho by A and 1B. The specific nuclei resonate at the angular frequency ωo represented by the following equation with respect to the static magnetic field Ho.

Ω o = γ Ho (1) In this equation (1), γ is a gyromagnetic ratio and is unique to the type of nucleus. Therefore, a rotating magnetic field H1 having an angular frequency .omega.o that resonates only specific nuclei is applied to the subject P via a pair of transmitting coils 2A and 2B provided in the probe head. By doing so, a specific slice portion S (which is a planar portion) that selectively acts on only the illustrated xy plane portion that is selectively set in the Z-axis direction by the linear magnetic field gradient Gz to obtain a tomographic image is obtained. MR phenomenon occurs only in a certain thickness). This MR phenomenon is caused by free induction attenuation (FID: Fr) via a pair of receiving coils 3A and 3B provided in the probe head.
ee Induction Decay) signal (hereinafter referred to as “FID signal”), and by performing a Fourier transform on this signal, a single spectrum is obtained at the rotation frequency of the specific nuclear spin. In order to obtain a tomographic image as a CT image, projected images of the slice portion S in multiple directions in the xy plane are required. Therefore, after the slice portion S is excited to cause the MR phenomenon, as shown in FIG. 12, the magnetic field Ho is moved in the x'-axis direction (the coordinate system rotated by an angle θ from the x-axis).
When a linear magnetic field gradient Gxy having a linear gradient is applied (by a coil (not shown) or the like), the equal magnetic field line E in the slice portion S of the subject P becomes a straight line, and the specific atomic nuclei on the constant magnetic field line E are straight lines. The spin rotation frequency is represented by the above equation (1). Here, for convenience of explanation, the equal magnetic field lines E are set to E1 ~
Let En be the magnetic field on each of the constant magnetic field lines E1 to En, and it is considered that signals D1 to Dn, which are a kind of FID signal, are generated. The amplitudes of the signals D1 to Dn are proportional to the specific nuclear spin densities on the isomagnetic field lines E1 to En penetrating the slice portion S, respectively. However, the actually observed FID signal is a combined FID signal in which all the signals D1 to Dn are added. Therefore, the composite FID signal is Fourier-transformed to obtain projection information (one-dimensional image) PD of the slice portion S on the x ′ axis. This x'axis is x
The magnetic field gradient Gxy is rotated in the -y plane (for example, the rotation of the magnetic field gradient Gxy is made as a composite magnetic field of the magnetic field gradients Gx and Gy in the x and y directions by two pairs of gradient magnetic field coils, and the magnetic field gradients Gx and Gy are generated. Is performed by changing the composition ratio of x) in the same manner as described above.
The projection information in each direction in the plane is obtained, and the CT image can be synthesized based on these pieces of information.

By the way, in this type of MR imaging apparatus, the probe head is arranged inside a coil for generating a static magnetic field and a gradient magnetic field, and a kind of coil (corresponding to a transmitting / receiving coil) surrounds the periphery of the subject. There is. In order to generate a high frequency electromagnetic wave that causes an MR phenomenon and to detect a weak MR signal, it is more efficient for the probe head to be in intimate contact with the subject as much as possible. It is prepared and used properly according to the diagnosis site.

For example, a probe head for the whole body is shown in FIG.
As indicated by reference numeral 4 in FIG. 3, it has a cylindrical shape.
As shown in FIG. 4, the abdomen and chest of the subject P are placed inside the probe head 4.

However, in the above case, when making a diagnosis,
It was not easy to efficiently detect a weak MR signal because a wide gap is created between the subject P lying on the bed and the probe head 4.

[0007]

SUMMARY OF THE INVENTION The present invention has been made based on the above circumstances, and its purpose is to:
It is an object of the present invention to provide a magnetic resonance imaging apparatus that includes a probe head that can easily detect a weak MR signal and that can obtain an image with excellent diagnostic ability.

[0008]

In order to achieve the above object, the present invention relates to a magnetic resonance imaging apparatus for detecting MR signals from an imaged region of a subject arranged inside a probe head to obtain image information. The probe head is formed of a plate-like flexible material so that it can be wound around the imaging region, and a positioning member that is formed according to the imaging region and determines the position of each part of the probe head is provided. Is.

[0009]

The operation of the magnetic resonance imaging apparatus having the above structure will be described.

A probe head is arranged on a top plate, and a subject imaging region is placed on the probe head. Next, the probe head is wound around the imaging region while the position of each part of the probe head is determined by the positioning member according to the imaging region.

Since the probe head has flexibility, it is convenient for handling when placing a subject on the probe head, and it is easy to handle, and when it is wrapped around the imaging site, it has good adhesion. Becomes

[0012]

EXAMPLES The present invention will be specifically described below with reference to examples.

FIG. 1 is a perspective view of an embodiment of a probe head used in the apparatus of the present invention.
Is a quadrangular plate that is long in the horizontal direction and has a symmetrical square hole 10.
A and 10B are formed, a cable 15 extends from the central portion, and a signal extracting connector 14 is attached to the tip thereof. The entire structure is flexible.

FIG. 2 shows a detailed configuration example of the probe head 10. Reference numeral 11 is a thin material (for example, 1 mm or less, preferably 0.1 mm) made of a flexible material (for example, vinyl chloride, polypropylene) having a predetermined plane area (for example, a size capable of covering the body of a patient as a subject).
The rectangular holes 10A and 10B having a predetermined size (for example, a size that allows a patient's arm to move in and out) are provided symmetrically across the intermediate portion 11A. This flexible substrate 1
It is preferable that 1 is a material having a small dielectric loss.
The shape of the hole is not limited to a corner and may be a circle.

Reference numeral 12 is a coil having a thickness of 100 μ, for example.
It is made of a thin copper plate of about m, is bent in the periphery of the square holes 10A and 10B and the intermediate region 11A and is connected endlessly, and is arranged so as to have a concave planar shape, such as a double-sided tape or an adhesive. It is mounted on the substrate 11 via. A circuit attachment portion 11B is provided at a position sandwiching the coil bending portion of the intermediate region 11A, and an output circuit and an adjustment circuit 13 are attached to the circuit attachment portion 11B so as to be connected to the upper and lower coils, respectively. A connector 14 is attached to 15 and its cable tip. The output circuit and the adjusting circuit 13 are for receiving the signal from the coil and adjusting the resonance condition at the working frequency according to the magnetic field strength, and include an adjusting capacitor, and the capacitance of the capacitor. Adjustment can be performed by changing. The connector 14 is connected to an external circuit and used for signal extraction and power supply.

Among the above-mentioned components, the cable 15 and the connector 14 are exposed so that the other components are covered with a cloth covering member. As a result, the probe head 10 has flexibility as a whole and is easily attached to the patient as described later. Moreover, there is an advantage that the surface is covered with a cloth so that the patient does not feel discomfort.

3 and 4 are a perspective view and a plan view showing an example of the positioning member 16 used when the probe head 10 is used. This is made of a synthetic resin U-shaped tube partially provided with a notch 16C, and has square holes 16A and 16B of the same size as the square holes 10A and 10B of the probe head 10 in the expanded state. Has been. It is preferable to prepare a plurality of such positioning members 16 so as to correspond to the size of the patient.

Next, an example of use of the probe head having the above structure will be described.

First, as shown in FIG. 5, the probe head 10 is attached to the top plate 17 of the MRI apparatus by an appropriate method. At this time, the intermediate area of the probe head 10 is the top plate 1.
The right and left square holes 10A and 10B are located on seven surfaces and are arranged so as to extend in a direction intersecting the longitudinal direction of the top plate 17. Then, the diagnostic site (for example, the chest) of the patient P is positioned so as to be placed via the top plate 17 and the intermediate region of the probe head 10.

Depending on the size of the patient, the probe head 1
In some cases, there is a margin between 0 and the patient P, which is not preferable. In such a case, as shown in FIG. 5, the positioning member 16 shown in FIGS. Place it so that it covers. Thereafter, as shown by the arrow in FIG. 5, both ends of the probe head 10 are bent to wrap the patient P, and finally, as shown in FIG. 6, both arms of the patient P are projected from the square holes 10A and 10B. In this state, both ends of the probe head 10 are butted against each other, and the butted parts are held by, for example, the magic fasteners 18, 18 which are attached in advance.

Now, the relationship between the position of the coil and the patient will be described. FIG. 7 shows the coil position when the probe head 10 covers the patient P, and the coil ends 12 are located above the center M of the patient P as a reference.
The angle formed by A and 12B and the coil 12 located below
Since it is said that the tuning efficiency is best when the coils are arranged such that the angles formed by C and 12D are 60 °, respectively, the arrangement of the coil 12 shown in FIG. 2 and FIGS.
It is preferable to set the shape of the positioning member shown in (1) to meet this purpose.

The present invention is not limited to the above embodiment, and various modifications can be made. For example, as shown in FIG. 8, the probe head 20 having no square holes is attached to the top plate 17, and the positioning member 26 having no square holes is covered on the body of the patient P while the patient P is placed as shown in FIG. After that, as shown in FIG. 10, both ends of the probe head 20 may be butted against each other at the upper side. Also in this case, the position of the coil is set to be the same as that in the above-mentioned embodiment.

In the above embodiment, the torso portion of the patient is targeted as the affected part, but the present invention is not limited to this, and it may be the head part or the leg part. The purpose can be achieved by preparing.

[0024]

As described in detail above, according to the present invention, since the probe head used in the apparatus has flexibility, it does not hinder the subject to lie on the top plate and is convenient in handling. Further, since the adhesion is good at the time of mounting, it becomes easy to efficiently detect even a weak MR signal, and thus it is possible to provide a magnetic resonance imaging apparatus capable of obtaining an image excellent in diagnostic ability.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a probe head used in a magnetic resonance imaging apparatus of the present invention.

FIG. 2 is a plan view for explaining the structure of the probe head shown in FIG.

FIG. 3 is a perspective view of a positioning member used when the probe head shown in FIG. 1 is used.

FIG. 4 is a plan view of a positioning member used when the probe head shown in FIG. 1 is used.

5 is a schematic perspective view showing a usage example of the probe head and the positioning member shown in FIG. 1. FIG.

FIG. 6 is a schematic perspective view showing an example of use of the probe head and the positioning member shown in FIG.

FIG. 7 is an explanatory diagram of a coil mounting position of the probe head shown in FIG.

FIG. 8 is a schematic perspective view for explaining a usage example according to another embodiment.

FIG. 9 is a schematic perspective view for explaining a usage example according to another embodiment.

FIG. 10 is a schematic perspective view for explaining a usage example according to another embodiment.

FIG. 11 is an explanatory diagram showing a principle configuration of MRI.

FIG. 12 is a principle diagram for obtaining projection information by a magnetic resonance phenomenon.

FIG. 13 is a perspective view showing a probe head in a conventional device.

14 is an explanatory diagram showing a relationship between the probe head shown in FIG. 13 and a subject.

[Explanation of symbols]

 10, 20 Probe head 11 Substrate 12 Coil 16, 26 Positioning member

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Claims (1)

[Claims] 1. A magnetic resonance imaging apparatus for obtaining image information by detecting an MR signal from an imaged region of a subject arranged inside a probe head, wherein the probe head is a plate-shaped flexible member that can be wound around the imaged region. A magnetic resonance imaging apparatus comprising a positioning member that is made of a conductive material and that is formed according to the imaging region and determines the position of each part of the probe head.