JPH024328A - Nuclear magnetic resonance imaging device - Google Patents

Abstract

PURPOSE:To obtain an optimum receiving condition regardless of the build of a checked body and the size of a checked part and to maintain high picture quality by forming a high frequency coil, which detects an electro-magnetic wave to be discharged from the checked body, with a material having flexibility. CONSTITUTION:A coil line material 30 of a high frequency coil 20 is composed of a soft coil line material such as a flat cable or FPC, for example. To the high frequency coil 20, connectors 31 and 32, which are composed of a non- magnetic substance and the material of small high frequency loss, a tuning circuit 33 to tune the high frequency coil 20 to a remove frequency, which is determined by magneto-static intensity, and a lead wire 34 for connection to a pre-amplifier are fit. At the time of image pick-up, for the high frequency coil 20, the coil line material 30 is wound along the checked part of the checked body and the connector 32 (female) is selected so that the length of the coil line material 30 can be most closed to the surrounding length of the checked part in the checked body. Then, after the connector (male) 31 is connected and the lead wire 34 is connected to the pre-amplifier, measurement is executed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a nuclear magnetic resonance imaging apparatus that obtains tomographic images of a subject using nuclear magnetic resonance phenomena, and in particular, to a nuclear magnetic resonance imaging apparatus that uses nuclear magnetic resonance phenomena to obtain a tomographic image of a subject. The present invention relates to a nuclear magnetic resonance imaging apparatus equipped with a high-frequency coil suitable for the imaging.

[Conventional technology]

Previous devices used radio frequency coils with a fixed shape that matched the average human body size. For this reason, high-frequency coils may not be able to be attached to particularly large people.
On the other hand, if you are a small person, you may be able to wear it, but the S/N of the image may be low.
There was a problem that the ratio deteriorated.

[Problem to be solved by the invention]

The above-mentioned conventional technology does not take into consideration the individual differences in the physique of the subject, and there is a problem in that the high-frequency coil cannot be attached to a large person or a pregnant woman. On the other hand, even if a high-frequency coil can be attached to a person with a small physique, it is too large than the optimal shape, resulting in problems 1 and J in which the S/N ratio of the obtained image deteriorates.

An object of the present invention is to provide a nuclear magnetic resonance imaging apparatus equipped with a high-frequency coil that can compensate for the individual differences in physique and adjust the shape to be optimal for each subject.

[Means for Solving the Problems] The above object includes means for generating a static magnetic field in the body axis direction of the subject or in a direction orthogonal thereto.

In a nuclear magnetic resonance imaging apparatus having a high-frequency coil that is disposed close to the subject and irradiates the subject with electromagnetic waves and detects electromagnetic waves emitted from the subject, the high-frequency coil is made of a flexible material. This can be achieved with a nuclear magnetic resonance imaging device characterized by being formed with.

In addition, by selecting a material such as a flat cable or FPC (flexible printed circuit board) for the high-frequency coil, and changing the length of the coil wire, it is possible to adjust the shape to suit the physique of the subject. Become.

[Effect]

A high-frequency coil made of a flexible material such as a flat cable can be wrapped around the test area of the test subject.For example, by attaching it to several locations on the cable and selecting connectors, the high-frequency coil can It becomes possible to set a high-frequency coil with optimal dimensions according to the person's physique. As a result, an optimal reception condition can be obtained regardless of the physique of the subject and the size of the examination site, and high image quality can be maintained.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 5 is a block diagram showing the overall configuration of the nuclear magnetic resonance imaging apparatus. This nuclear magnetic resonance imaging device obtains a tomographic image of a subject by using the nuclear magnetic resonance (NM) phenomenon, and includes a static magnetic field generating magnet 10, a central processing unit (
It consists of a CPU) 11, a sequencer 12, a transmission system 13, a magnetic field gradient generation system 14, a reception system 15, and a signal processing system 16.

The static magnetic field generating magnet 10 generates a strong and uniform static magnetic field around the subject 1 in the body axis direction or in a direction perpendicular to the body axis, and is used to generate a strong and uniform static magnetic field around the subject 1 in a certain expanse of space around the subject 1. A magnetic field generating means of a permanent magnet type, a normal conduction type, or a superconducting type is arranged in the magnetic field. The sequencer 12 operates under the control of the CPU 11 and sends various commands necessary for data collection of tomographic images of the subject 1 to the transmission system 13, magnetic field gradient generation system 14, and reception system 15. The transmission system 13 includes a high-frequency oscillator 17, a modulator 18, a high-frequency amplifier 19, and a high-frequency coil 20a on the transmitting side. However, by amplifying this amplitude-modulated high-frequency pulse with a high-frequency amplifier 19 and then supplying it to a high-frequency coil 20a placed close to the subject 1, the subject 1 is irradiated with electromagnetic waves. There is. The magnetic field gradient generation system 14 is composed of gradient magnetic field coils 21 wound in the three axes of x, y, and z, and a gradient magnetic field power supply 22 that drives each coil. X by driving the gradient magnetic field power supply 22 of the coil.

Gradient magnetic fields Gx, Gy, and Gz in three y- and z-axis directions are applied to the subject 1. Depending on how this gradient magnetic field is applied, a slice plane for the subject l can be set. The receiving system 15 includes a solenoid-type high-frequency coil 20b on the receiving side, an amplifier 23, a quadrature phase detector 24, and an A/D converter 25. The electromagnetic wave (NMR signal) of response 1 is detected by a high frequency coil 20b placed close to the subject 1, and is inputted to an A/D converter 25 via an amplifier 23 and a quadrature phase detector 24 to be converted into a digital quantity. The signal is converted into two series of collected data which are further sampled by the quadrature phase detector 24 at the timing according to the command from the sequencer 12, and the signals are sent to the signal processing system 16. This signal processing system 16 includes a CPU 1, a recording device such as a magnetic disk 26 and a magnetic tape 27, and a display 28 such as a CRT.
The CPU II performs processing such as Fourier transformation, correction coefficient calculation, and image reconstruction, and the signal intensity distribution of an arbitrary cross section or the distribution obtained by performing appropriate calculations on a plurality of signals is converted into an image and displayed on the display 28. It is designed to be displayed. In addition, in FIG. 5, the high-frequency coils 20a, 20b and the gradient magnetic field coil 21 on the transmitting side and the receiving side are arranged in the magnetic field space of the static magnetic field generating magnet 10 arranged in the space around the subject 1. .

A high-frequency coil portion, which is the main part of the first embodiment of the present invention, is shown in FIGS. 1 and 2. The coil wire 30 of the high-frequency coil 2o as shown in FIG. 1 is made of a flexible coil wire, such as a flat cable or FPC (flexible printed circuit board). Connectors 31, 32 made of materials with low loss, such as epoxy resin or Teflon.
A tuning circuit 33 for tuning the high frequency coil 20 to the Larmor frequency determined by the strength of the static magnetic field and a lead wire 34 for connecting to the preamplifier are attached. A plurality of connectors (female) 32 are attached at appropriate positions on the coil wire 3o so that a plurality of lengths of the coil wire 3o can be selected. During image transfer, the high-frequency coil 20 winds a coil wire 30 along the inspection site of the subject.
The connector (female) 32 is selected so that its length is closest to the circumference of the test site of the subject, the connector (male) 31 is connected, the lead wire 34 is connected to the preamplifier, and then measurement is performed.

In the prior art, the length of the coil wire 30 was constant and was installed on a solid bobbin.

It is impossible to adjust the optimum dimensions of the high-frequency coil 20 according to the examination site of the subject, and variations in image quality are observed due to individual differences among the subjects. but.

According to the present invention, the above adjustment has become possible.

FIG. 2 shows an example of adjusting the length of the coil wire 3o of the high frequency coil 2o. FIG. 2(a) shows an example in which three connectors (female) 32 are attached, and the length of the coil wire 30 is maximized. This is obtained by connecting the connector (male) 31 to the connector (female) 32 closest to the end. connector(
By changing the female (female) 32 from the end to the inner one and connecting them, the coil wire 30 becomes gradually shorter. Figure 2(b)
shows the case where the coil wire 30 is made the shortest. in this case,
Extra connector (female) 32 on the outside of the ring-shaped coil
The remaining coil wire material does not have the function of a coil. By changing the length of the coil wire 30, the number of tubes of the connector (female) 32, and the installation interval based on the above implementation principle,
It is possible to configure the high-frequency coil 20 that compensates for individual differences in the physique of the subject and differences in the size of the test site. By using the above-described high-frequency coil, it is possible to solve the problem of mounting the high-frequency coil and the problem of variations in image quality due to individual differences in subjects.

FIG. 3 shows a second embodiment. In the first embodiment shown in FIG. 2, the adjustment interval of the length of the coil wire 30 is
Female) Determined by the spacing of the 32 arrays. Connector (female)
When arranging the coil wires 32, they are usually arranged at regular intervals, so the length of the coil wire 30 that exactly matches the physique of the subject may be located between the two connectors (female) 32.

In such a case, the embodiment shown in FIG. 3(a) is appropriate. The basic configuration is the same as in Figure 2, with coil wire 3
0, connectors 31, 32, tuning circuit 33, lead wire 34
It consists of However, in FIG. 3, a hook-and-loop fastener 36 is used as the connecting portion to form a single loop between the high-frequency coils, which is greatly different from the connection using only the connector shown in FIG. 2.

When the hook-and-loop fastener 36 is used, the length of the connecting portion can be arbitrarily changed within a variable range, so that a loop of the coil wire 30 can be formed at a position that best suits the physique of the subject. Since the hook-and-loop fastener itself has no conductivity and only has a mechanical fixing function, the electrical connection is made after fixing with the hook-and-loop fastener. This is done by connecting the connector (male) 31 at the tip of the connector 35 to the connector (female) 32. Connection line 3
The length 5 is such that the connectors 31 and 32 can be connected whenever the hook and loop fastener 36 is fixed at any position within its variable connection range. In this example, connectors 31 and 32
It becomes possible to fix the high-frequency coil to the trunk of the subject's body without applying force to the body.

FIG. 4 shows a third embodiment. The high frequency coil 20 of this embodiment includes a coil wire 3o, a tuned circuit 33, and a lead wire 34.
, roller 37. It is composed of a roller pressure pin 38. The difference from FIG. 3 is that instead of fixing with hook-and-loop fasteners, it is fixed with rollers and roller pressure pins. The length of the coil wire 30 is constant like that installed on a conventional solid bobbin, but it is a single coil without division. When the high-frequency coil is attached to the test site of the test subject as shown in Figure 4(b), the roller 3 should be placed in close contact with the test site of the test subject.
7 and roller crimp pin 38. For convenience when attaching to the test object, insert connectors 31 and 32 in the middle.
It can also be divided.

〔Effect of the invention〕

As explained above, the present invention includes a solenoid-shaped high-frequency coil that irradiates electromagnetic waves to a subject or detects electromagnetic waves emitted from the subject, which is made of a flexible material such as a flat cable. This makes it possible to wrap the high-frequency coil along the test site of the subject. Furthermore, by mechanically dividing the high-frequency coil into two and providing a plurality of connectors, the high-frequency coil can be adjusted to an optimal size regardless of the individual differences in body size of the subject. As a result, it is possible to configure a high-frequency coil with an optimal size regardless of the physique of the subject and the size of the examination site, which has the effect of reducing variations in image quality due to individual differences and maintaining high image quality.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the overall configuration of a high-frequency coil according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing how the above-mentioned high-frequency coil is used, and FIGS. 3 and 4 are high-frequency diagrams of other embodiments. FIG. 5 is a block diagram showing the overall configuration of the nuclear magnetic resonance imaging apparatus according to the present invention. 1... Subject, 10... Static magnetic field generating magnet, 11...
・CPU (Central Processing Unit), 12...Sequencer, 1
3... Transmission system, 14... Magnetic field gradient generation system, 15...
・Reception system, 16... Signal processing system, 20... High frequency coil, 3o... Coil wire, 31... Connector (male), 32... Connector (female), 33... Tuning circuit ,
34... Lead wire. 35... Connection wire, 36... Velcro fastener, 37...
Laura, chart I, chart tea (ω

Claims (1)

[Claims] 1. A magnet that generates a static magnetic field in the direction of the body axis of the subject or in a direction perpendicular thereto, and is placed close to the subject and irradiates the subject with electromagnetic waves. A nuclear magnetic resonance imaging apparatus comprising a high frequency coil for detecting electromagnetic waves emitted from the subject, characterized in that the high frequency coil is made of a flexible material. 2. Cut the high frequency coil and attach a connector (male,
Attach a plurality of connectors (female or male) to the other end of the coil wire at intervals along the length direction of the coil wire, and change the loop length of the high-frequency coil by changing the connections of the connectors. The nuclear magnetic resonance imaging apparatus according to claim 1, wherein the nuclear magnetic resonance imaging apparatus is configured to be able to perform the following functions. 3. Cut the high frequency coil and attach a connector (female,
Or attach a connector (male or female) and the remaining side of the hook-and-loop fastener to one end of the hook-and-loop fastener, and change the loop length of the high-frequency coil by changing the connection length of the hook-and-loop fastener. 2. The nuclear magnetic resonance imaging apparatus according to claim 1, wherein the high-frequency coil is electrically connected by connecting a connector. 4. A stopper such as a roller is attached to the high-frequency coil, and the loop length of the high-frequency coil can be changed by changing the position of the stopper. Nuclear magnetic resonance imaging device.