JPH0654825A - Probe for nuclear magnetic resonance device - Google Patents

Abstract

PURPOSE:To provide the probe for a nuclear magnetic resonance device for improving S/N of a local photographing probe device, and obtaining an image of a good quality. CONSTITUTION:In a plate-like base 10 being horizontal to an X-Z plane, a first surface coil 1 is molded, and on a Y-Z plane being orthogonal to the base 10, an orthogonal part 11 to which a second surface coil 2 molded is arranged. A first surface coil 1 detects an NMR signal in the Y direction of a nuclear spin for rotating on an X-Y plane being crthogonal to the static magnetic field direction (Z axis direction). On the other hand, a second surface coil 2 detects an NMR signal in the X direction of the nuclear spin for rotating on the X-Y plane. The probe for a nuclear magnetic resonance device is constituted so as to obtain simultaneously information from a first surface coil and a second surface coil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention detects a nuclear magnetic resonance (hereinafter referred to as "NMR") signal from hydrogen, phosphorus, etc. in an object to visualize a nuclear spin density distribution and relaxation time distribution. The present invention relates to a probe for a nuclear magnetic resonance apparatus, and more particularly to a probe for a nuclear magnetic resonance apparatus that facilitates attachment to a lower limb such as a knee and that can improve S / N.

[0002]

2. Description of the Related Art Conventionally, in a nuclear magnetic resonance apparatus, various types of head probe, abdominal probe, knee probe and field of view surrounding a region of interest of a subject (for example, a person) are limited, but the above-mentioned probe is used. The inspection and imaging of the subject have been performed using a surface coil or the like, which has a higher sensitivity than the above.
Conventionally, when imaging the knee of a subject, the knee probe is of a size that surrounds one knee, so the foot must be inserted into the knee probe, and the wearing is troublesome. There is a problem that it is difficult to fit the knee probe to the center of the region. On the other hand, by providing a coil support portion that supports the surface coil so as to intersect with the base portion on the base portion formed in a flat plate shape, local imaging for solving this problem is performed. A probe device for use is described in JP-A 1-249043.

[0003]

The local imaging probe device shown in the above prior art is easy to mount on the knee of the subject, and the central part of the probe device can be easily located in the center of the imaging area. Although they can be matched, there is a problem that the S / N is lower than that of a knee probe that surrounds the knee and a high quality image cannot be obtained. The present invention has been made in view of the above, and an object of the present invention is to solve the above-mentioned problems in the prior art, improve the S / N, and obtain a high quality image. It is to provide bu.

[0004]

Nuclear magnetic resonance for exciting at least one of nuclear spins of a subject placed in a predetermined space by a high frequency magnetic field and detecting a nuclear magnetic resonance signal from the nuclear spins of the subject. In the device probe, a base having a first surface coil and a second base in a direction orthogonal to the base.
The orthogonal portion having the surface coil is provided so as to simultaneously obtain information from the first surface coil and the second surface coil. The first surface coil is composed of two unit surface coils arranged at a predetermined interval and a compensation coil overlapping each unit surface coil so as to eliminate mutual coupling between the unit surface coils. Further, the first and second surface coils are composed of a phased array coil in which a plurality of unit surface coils are arranged such that each unit surface coil is overlapped with the adjacent coil so as to minimize mutual coupling. Become. The base is provided with two balloons that can be expanded and contracted by air, and the orthogonal portion is configured to be attachable to and detachable from the base. Furthermore, a belt or an elastic band for fixing the subject is provided on at least one of the base and the orthogonal portion. The outputs from the first and second surface coils are configured so that the outputs from the first and second surface coils are added after adjusting the phase difference and the level difference to the optimum addition condition according to the imaging region. Are detected by independent receivers, the detected output data is stored in a storage device, and the output data is reconstructed during image reconstruction.
Synthesize the data.

[0005]

In the probe for a nuclear magnetic resonance apparatus according to the present invention, the base having the first surface coil and the orthogonal portion having the second surface coil in the direction orthogonal to the base are provided to provide the first Since the information from the surface coil and the information from the second surface coil are obtained at the same time, the S / N of the local imaging probe device according to the conventional technique is improved and a high quality image can be obtained.

[0006]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a diagram showing a probe for an NMR apparatus according to an embodiment of the present invention. A first surface coil 1 is molded in a flat plate-shaped substrate 10 which is horizontal to the XZ plane, and an orthogonal portion 11 in which a second surface coil 2 is molded is arranged on a YZ plane orthogonal to the substrate 10. It The first surface coil 1 detects the NMR signal in the Y direction of the nuclear spin rotating on the XY plane orthogonal to the static magnetic field direction (Z axis direction). On the other hand, the second surface coil 2 detects the NMR signal in the X direction of the nuclear spin rotating on the XY plane. That is, as shown in FIG. 2, the first surface coil 1 forms a magnetic field in the Y direction, and the second surface coil 2 forms the first surface coil 1.
A magnetic field is formed in the X direction orthogonal to the magnetic field formed by. Therefore, since no interference occurs between the first surface coil 1 and the second surface coil 2, it is possible to simultaneously detect signals from the respective coils. In addition, in FIG.
The second surface coil is a rectangular coil, but the same applies to a circular or elliptical coil. Further, in the present embodiment, a flat plate-shaped member for molding the entire coil on the base 10 and the orthogonal portion 11 is used, but a member supporting only a part of each coil or a copper wire (or a copper plate) of each coil is used.
It is not limited to this, and it is possible to mold only a part. As a result, the QD (Quadrature Detection) method using the first surface coil 1 and the second surface coil 2 becomes possible, which is easy to attach to the knee of the subject and the center of the imaging region. The S / N can be improved without losing the advantage that the center portion of the probe can be easily aligned with the portion.

The QD method is a method for detecting a rotating high-frequency magnetic field with high sensitivity by detecting two linear magnetic field signals which are orthogonal to each other and synthesizing them by shifting their phases by 90 degrees.
When the signal intensities from the orthogonal coils are equal to each other, the sensitivity is ideally improved by a factor of 2 with respect to the single linear magnetic field detection method. This method is described in the Journal of Magnetic Resonance.
e) 53, p.324-327 (1983). Figure 3
2 shows another embodiment of the first surface coil in the embodiment of FIG. There are unit surface coils 3a and 3b arranged on one plane with a certain distance D.
Unit surface coils 3a, so as to eliminate interference between 3b,
The compensation coil 3c is arranged so as to appropriately overlap with 3b to form the surface coil 3. Unit surface coil 3a,
An orthogonal plate (not shown) in which the second surface coil is molded is arranged on the YZ plane on the center (X = 0) between 3b.
The unit coils 3a and 3b (which are rectangular coils in the figure, but may be circular or elliptical coils) are Y directions of nuclear spins that rotate on an XY plane orthogonal to the static magnetic field direction (Z axis direction). The NMR signal of is detected. That is, FIG.
, The surface coil 3 forms two equally sensitive magnetic fields in the Y direction, and the second surface coil is the surface coil 3
A magnetic field is formed in the X direction orthogonal to the magnetic field formed by. Therefore, since no interference occurs between the surface coil 3 and the second surface coil, it becomes possible to detect signals from the respective coils at the same time. The feature of the present embodiment is that the surface coil uses the property that the sensitivity becomes higher when the surface coil is made smaller, and the surface coil 3 constituting the first surface coil 3 is used.
By making a and 3b appropriately small, the S / N in the QD method is further improved.

FIG. 5 shows still another embodiment of the first surface coil in the embodiment of FIG. The phased array coil 4 is an array of unit surface coils 4a and 4b (not limited to two) arranged in the X direction.
b (a rectangular coil in the figure, but it may be a circular or elliptical coil) is overlapped by a distance d that minimizes mutual coupling. The phased array coil 4 is molded on a substrate (not shown),
Center of overlap of unit surface coils 4a, 4b (X =
On the YZ plane above 0), the orthogonal portion obtained by molding the second surface coil is arranged. Phased array coil 4
Detects the NMR signal in the Y direction of the nuclear spin rotating on the XY plane orthogonal to the static magnetic field direction (Z axis direction). That is, the phased array coil 4 has high sensitivity in the Y direction,
A wide range magnetic field is formed, and the second surface coil forms a magnetic field in the X direction orthogonal to the magnetic field formed by the phased array coil 4. Therefore, since no interference occurs between the phased array coil 4 and the second surface coil, it becomes possible to detect signals from the respective coils at the same time. The feature of this embodiment is that by using the phased array coil 4 as the first surface coil, high sensitivity and a wide field of view are achieved, and the S / N in the QD method is further improved. In this embodiment, the phased array coil is used only for the first surface coil molded in the substrate, but the same effect can be obtained by using the phased array coil for the second surface coil molded in the orthogonal portion. Needless to say.

FIG. 6 is a diagram showing a probe for an NMR apparatus according to an embodiment of the present invention. A first surface coil (not shown) is molded in a flat plate-shaped substrate 10 which is horizontal to the X-Z plane, and a second surface coil (not shown) is provided on a Y-Z plane orthogonal to the substrate 10. The molded orthogonal portion 11 is arranged. The surface of the base 10 is provided with two balloons 12 whose expansion and contraction can be adjusted by air. The balloon 12 is effective when the knee is bent and an image is taken, and the inflation and deflation are freely adjusted by taking in and out air so that the knee can be bent appropriately without burdening the subject. As a result, it is possible to easily perform imaging with the knee extended and the knee bent. FIG. 7 shows an NM which is an embodiment of the present invention.
It is a figure which shows the probe for R apparatuses. A first surface coil (not shown) is molded in the base 10 on a flat plate, and a removable orthogonal portion 11 in which a second surface coil (not shown) is molded is arranged on a plane orthogonal to the base 10. To be done. Foundation 1
A non-magnetic connector 13 is used for the connecting portion between 0 and the orthogonal portion 11, and the orthogonal portion 11 is fixed to the base 10 by inserting the connector 13 into the connector 13. When actually mounting the probe on the knee, the base 10 is fixed to the bed of the NMR apparatus,
The subject lies on the bed with his knees above it. Thereafter, the orthogonal portion 11 is inserted into the connector 13, and the knee portion is fixed to at least one of the base 10 and the orthogonal portion 11 with a belt or an elastic band (not shown). That is, since the probe can be attached to the subject simply by lying on the bed, the burden on the subject can be reduced and the operability of the probe can be improved. In this embodiment, the connector 13 is used to fix the base 10 and the orthogonal portion 11, but the concave portion is provided on one of the magic tape or the base 10 or the orthogonal portion 11, and the convex portion is provided on the other side to fix the same. Well well this is not the case.

FIG. 8 shows a block diagram of a receiving system using the phased array coil 4 of FIG. 5 as the first surface coil. To the input ends 20-1 and 20-2, the unit surface coils 4a and 4b of the phased array coil 4 which are arranged one-dimensionally so as to minimize mutual coupling are connected, and the input ends 20-1 and 20-2 are connected. -2, each of the NMR signals received by the preamplifier 21 has an impedance matching circuit.
It is amplified by -1, 21-2 and added by the adder 22-1. The second surface coil 2 shown in FIG. 1 is connected to the input end 20-3, and the NM received by the input end 20-3 is received.
The R signal is amplified by the preamplifier 21-3 having an impedance matching circuit. Also, the outputs of the adder 22-1 and the preamplifier 21-3 are the phase shifters 23-1 and 23-2 (for example, 23
-1 is set to 0 degrees, 23-2 is set to about +90 degrees or -90 degrees), and Athene for adjusting to the optimum addition condition
After passing through the data 24-1 and 24-2, the adder 22-2 performs addition. The output of the adder 22-2 is the quadrature phase detector 25.
The digital signal is converted into a digital signal by the A / D converter 26 and guided to a computer (not shown).

In this way, the sensitivity (S
The sensitivity distribution of the coil can be controlled so that / N) becomes high, and the S / N can be improved.

FIG. 9 shows another block diagram of a receiving system using the phased array coil 4 of FIG. 5 as the first surface coil. To the input ends 20-1 and 20-2, the unit surface coils 4a and 4b of the phased array coil 1 which are one-dimensionally arranged so as to minimize mutual coupling are connected, and the input ends 20-1 and 20-2 are connected. Each NMR signal received at -2 is
They are amplified by preamplifiers 21-1 and 21-2 each having an impedance matching circuit and added by an adder 22. The second surface coil 2 (see FIG. 1) is connected to the input end 20-3, and the NMR signal received at the input end 20-3 is a preamplifier 21 having an impedance matching circuit.
It is amplified by -3. Adder 22 and preamplifier 21-
The respective outputs of 3 are phase shifters 23-1, 23-2 (for example, 23-1 is 0 degree, 2
3-2 is set to about +90 degrees or -90 degrees), and an attenuator 24-1 for adjusting to the optimum addition condition,
After passing through 24-2, quadrature phase detectors 25-1, 25
-2, is converted into a digital signal (detection data) by the A / D converters 26-1 and 26-2, and is guided to the computer 27. Each detection data led to the computer 27 is calculated by the computer 2
7 is temporarily stored in a storage device (not shown) in the inside and is synthesized on the image when the image is reconstructed, so that the signal synthesis that makes the most effective use of the information amount can be performed. Although the NMR signals are added by the adder 22 in this embodiment, the phase shifter, attenuator, quadrature phase detector,
The same operation can be performed by using two systems of A / D converters. By doing this, the sensitivity (S / N) is high, and the sensitivity distribution is controlled on the image so that the sensitivity uniformity is excellent.
It is possible to improve the S / N further.

[0013]

As described above in detail, according to the present invention, the base having the first surface coil and the orthogonal portion having the second surface coil in the direction orthogonal to the base are provided to provide the first surface coil. Since it is configured to obtain information from the surface coil and the second surface coil at the same time, the probe for a nuclear magnetic resonance apparatus can improve S / N and obtain a high quality image as compared with the conventional local imaging probe. This is a remarkable effect that can be realized.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a probe for a nuclear magnetic resonance apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a sensitivity distribution of a probe for a nuclear magnetic resonance apparatus shown in the embodiment of FIG.

FIG. 3 is a diagram showing another embodiment of the first surface coil in the embodiment of FIG.

FIG. 4 is a diagram showing the sensitivity distribution of the probe for a nuclear magnetic resonance apparatus shown in the embodiment of FIG.

FIG. 5 is a view showing still another embodiment of the first surface coil in the embodiment of FIG.

FIG. 6 shows a nuclear magnetic resonance apparatus professional according to another embodiment of the present invention.
FIG.

FIG. 7 is a diagram showing the configuration of a probe for a nuclear magnetic resonance apparatus according to still another embodiment of the present invention.

8 is a block diagram of a receiving system using the phased array coil of FIG. 5 as a first surface coil.

9 is another block diagram of a receiving system using the phased array coil of FIG. 5 as the first surface coil.

[Explanation of symbols]

1 ... 1st surface coil, 2 ... 2nd surface coil, 3 ... surface coil, 3a, 3b, 4a, 4b ... unit surface coil,
3c ... Compensation coil, 4 ... Phased array coil, 10
... Flat plate base, 11 ... Orthogonal part, 12 ... Balloon, 13
... Non-magnetic connectors, 20-1, 20-2, 20-3 ...
Input terminals, 21-1, 21-2, 21-3 ... Preamplifier,
22-1, 22-2 ... Adder, 23-1, 23-2 ... Phase shifter, 24-1, 24-2 ... Attenuator, 25,
25-1, 25-2 ... Quadrature phase detector, 26, 26-
1, 26-2 ... A / D converter, 27 ... Calculator.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Etsuji Yamamoto 1-280, Higashi Koigokubo, Kokubunji, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd.

Claims (9)

[Claims] 1. A probe for a nuclear magnetic resonance apparatus for exciting at least one of nuclear spins of a subject placed in a predetermined space by a high frequency magnetic field and detecting a nuclear magnetic resonance signal from the nuclear spins of the subject. In, a base having a first surface coil and an orthogonal portion having a second surface coil in a direction orthogonal to the base are provided, and information from the first surface coil and the second surface coil is simultaneously received. A probe for a nuclear magnetic resonance apparatus, which is configured to obtain. 2. The first surface coil overlaps two unit surface coils arranged at a predetermined interval and each unit surface coil so as to eliminate mutual coupling between the respective unit surface coils. The probe for a nuclear magnetic resonance apparatus according to claim 1, comprising a compensation coil. 3. A phased array coil in which the first surface coils are arranged such that a plurality of unit surface coils are overlapped with each other such that each unit surface coil has a minimum mutual coupling with an adjacent coil. The probe for a nuclear magnetic resonance apparatus according to claim 1, wherein the probe comprises: 4. A phased array coil in which the second surface coils are arranged such that a plurality of unit surface coils are overlapped with each other so that each unit surface coil has a minimum mutual coupling with an adjacent coil. The probe for a nuclear magnetic resonance apparatus according to claim 1, wherein the probe comprises: 5. The probe for a nuclear magnetic resonance apparatus according to claim 1, wherein the base is provided with two balloons that can be expanded and contracted by air. 6. The probe for a nuclear magnetic resonance apparatus according to claim 1, wherein the orthogonal portion is attachable to and detachable from the base. 7. The probe for a nuclear magnetic resonance apparatus according to claim 1, further comprising a belt or an elastic band for fixing a subject on at least one of the base and the orthogonal portion. 8. The configuration is such that outputs from the first surface coil and the second surface coil are added after adjusting a phase difference and a level difference to optimal addition conditions according to an imaging region. The probe for a nuclear magnetic resonance apparatus according to claim 1. 9. The outputs from the first surface coil and the second surface coil are detected by independent receivers, respectively, and the detected output data is stored and stored, and then the image is reconstructed at the time of image reconstruction. The probe for a nuclear magnetic resonance apparatus according to claim 1, wherein the probe is configured to synthesize output data.