JP3340466B2 - Receiving system using a probe for nuclear magnetic resonance equipment. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects nuclear magnetic resonance (hereinafter, referred to as "NMR") signals from hydrogen, phosphorus, etc. in a subject, and visualizes the density distribution and relaxation time distribution of nuclear spins. 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 which can be easily attached to a lower leg such as a knee and can improve S / N, and a receiving system using the same .

[0002]

2. Description of the Related Art Conventionally, in a nuclear magnetic resonance apparatus, various types of head probes, abdominal probes, knee probes, and a field of view surrounding a site of interest of a subject (for example, a human) are limited. Inspection and imaging of a subject have been performed using a surface coil or the like having higher sensitivity than that of the above.
Conventionally, when imaging the knee of a subject, the knee probe is of such a size as to surround one knee, so that the foot must be inserted into the knee probe and mounting is troublesome. There is a problem that it is difficult to align the knee probe with the center of the region. On the other hand, by providing a coil support portion that supports a surface coil so as to intersect with the base portion on a base portion formed in a flat shape, local imaging for solving this problem is performed. A probe device for use is described in Japanese Patent Application Laid-Open No. 1-249043.

[0003]

The probe apparatus for local imaging described in the above-mentioned prior art can be easily mounted on the knee of the subject, and the center of the probe apparatus can be easily positioned at 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. SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing, and an object of the present invention is to solve the above-mentioned problems in the prior art, improve the S / N ratio, and obtain a high-quality image for a nuclear magnetic resonance apparatus. Use
To provide a receiving system .

[0004]

A nuclear magnetic resonance system which excites nuclear spins of a subject placed in a predetermined space by a high-frequency magnetic field and / or detects nuclear magnetic resonance signals from the nuclear spins of the subject. In a device probe, a base having a first surface coil and a second base in a direction orthogonal to the base are provided.
Is provided so that information from the first surface coil and the information from the second surface coil are obtained at the same time. The first surface coil includes 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 formed from a phased array coil in which a plurality of unit surface coils are arranged so as to overlap each other so that each unit surface coil has a minimum mutual coupling with an adjacent coil. Become. The base is provided with two balloons that can be inflated and contracted by air, and the orthogonal portion is configured to be detachable from the base. Further, a belt or an elastic band for fixing the subject is provided on at least one of the base and the orthogonal portion. The output from the first and second surface coils is configured to add the output from the first and second surface coils after adjusting the phase difference and the level difference to the optimum addition condition according to the imaging site. Are detected by independent receivers, and the detected output data is stored and stored in a storage device.
Synthesize the data.

[0005]

In a probe for a nuclear magnetic resonance apparatus according to the present invention, 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. Since the configuration is such that information from the surface coil and the second surface coil can be obtained at the same time, the S / N of the conventional local imaging probe device is improved, and a high-quality image can be obtained.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a probe for an NMR apparatus according to one embodiment of the present invention. A first surface coil 1 is molded in a flat plate-shaped base 10 parallel to the XZ plane, and an orthogonal portion 11 in which the second surface coil 2 is molded is arranged on a YZ plane orthogonal to the base 10. You. The first surface coil 1 detects an NMR signal in the Y direction of a nuclear spin rotating on an XY plane orthogonal to the static magnetic field direction (Z axis direction). On the other hand, the second surface coil 2 detects an NMR signal in the X direction of a 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
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 detect signals from each coil simultaneously. Note that 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-like member for molding the entire coil is used for the base 10 and the orthogonal portion 11, but a plate for supporting only a part of each coil or a copper wire (or copper plate) for each coil is used.
It is not limited to this, and only the part may be molded. Thus, a QD (Quadrature Detection) method can be performed by using the first surface coil 1 and the second surface coil 2, and it is easy to attach the subject to the knee, and the center of the imaging region can be easily detected. The S / N can be improved without deteriorating the advantage that the center of the probe can be easily adjusted to the portion.

The QD method is a method for detecting a rotating high-frequency magnetic field with high sensitivity by detecting two orthogonal linear magnetic field signals and synthesizing them by shifting their phases by 90 degrees.
If the signal intensities from the orthogonal coils are equal to each other, the sensitivity is ideally improved by a factor of √2 over a single linear magnetic field detection method. This method is described in the Journal of Magnetic Resonanc.
e) Volume 53, pages 324 to 327 (1983). FIG.
Next, another embodiment of the first surface coil in the embodiment of FIG. 1 is shown. There are unit surface coils 3a, 3b arranged on one plane with a certain interval D, and the unit surface coils 3a,
3b, the unit surface coils 3a,
The compensation coil 3c is disposed so as to overlap with the portion 3b appropriately, and forms the surface coil 3. Unit surface coil 3a,
On the YZ plane on the center (X = 0) between 3b, an orthogonal plate (not shown) in which the second surface coil is molded is arranged.
The unit coils 3a and 3b (rectangular coils in the figure, but may be circular or elliptical coils) are the Y directions of nuclear spins rotating on an XY plane orthogonal to the static magnetic field direction (Z axis direction). Is detected. That is, FIG.
As shown in the figure, the surface coil 3 forms two equal sensitive magnetic fields in the Y direction, and the second surface coil 3
A magnetic field is formed in the X direction orthogonal to the magnetic field formed by. Therefore, no interference occurs between the surface coil 3 and the second surface coil, and it is possible to detect signals from each coil simultaneously. The feature of the present embodiment is that the surface coil uses the property that the sensitivity increases when the surface coil is reduced.
a, 3b are appropriately reduced, and 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 formed by arranging unit surface coils 4a and 4b (not necessarily two) in the X direction.
b (a rectangular coil in the figure, but may be a circular or elliptical coil) is overlapped by a distance d such that mutual coupling is minimized. The phased array coil 4 is molded on a base (not shown),
The center of the overlap between the unit surface coils 4a and 4b (X =
0) On the YZ plane on the upper side, an orthogonal portion molded with the second surface coil is arranged. Phased array coil 4
Detects an NMR signal in the Y direction of a nuclear spin rotating on an 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,
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, signals can be simultaneously detected from each of the coils. The feature of the present embodiment is that by using the phased array coil 4 as the first surface coil, a 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 base, 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 shows 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 substrate 10 horizontal to the XZ plane, and a second surface coil (not shown) is mounted on a YZ plane orthogonal to the substrate 10. The molded orthogonal part 11 is arranged. On the surface of the base 10, two balloons 12 that can be adjusted in expansion and contraction by air are provided. The balloon 12 is effective when the image is taken with the knee bent. The balloon 12 adjusts the expansion and contraction freely by taking in and out of air so that the knee can be bent appropriately without imposing a burden on the subject. Accordingly, it is possible to easily perform imaging in a state where the knee is extended and a state where the knee is bent. FIG. 7 shows an NM according to 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 a base 10 on a flat plate, and a detachable orthogonal portion 11 in which a second surface coil (not shown) is molded is arranged on a plane orthogonal to the base 10. Is done. Base 1
A non-magnetic connector 13 is used for a connection portion between the 0 and the orthogonal portion 11, and is fixed to the base 10 by inserting the orthogonal portion 11 into the connector 13. When actually attaching the probe to the knee, the base 10 is fixed to the bed of the NMR apparatus,
The subject lies on the bed with his knees on top. 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 subject can mount the probe only by lying on the bed, the burden on the subject can be reduced and the operability of the probe can be improved. In the present embodiment, the connector 13 is used to fix the base 10 and the orthogonal part 11. This is not always 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. The input terminals 20-1 and 20-2 are connected to the unit surface coils 4a and 4b of the phased array coil 4 arranged one-dimensionally so as to minimize mutual coupling. -2 received by the preamplifier 21 having an impedance matching circuit.
-1, 21-2, and are added by the adder 22-1. The second surface coil 2 previously shown in FIG. 1 is connected to the input terminal 20-3, and the NM received by the input terminal 20-3 is received.
The R signal is amplified by a preamplifier 21-3 having an impedance matching circuit. The outputs of the adder 22-1 and the preamplifier 21-3 are phase shifters 23-1 and 23-2 (e.g., 23
-1 is set to 0 degrees, 23-2 is set to about +90 degrees or -90 degrees), and Attenuation for adjusting to the optimum addition condition.
After passing through the filters 24-1 and 24-2, they are added by an adder 22-2. The output of the adder 22-2 is a quadrature detector 25.
Are converted to digital signals by the A / D converter 26 and guided to a computer (not shown).

By doing so, the sensitivity (S
/ N) can be controlled so that the coil sensitivity distribution can be controlled, and 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. The input terminals 20-1 and 20-2 are connected to the unit surface coils 4a and 4b of the phased array coil 1 arranged one-dimensionally so as to minimize mutual coupling. Each NMR signal received at -2 is
Each is amplified by preamplifiers 21-1 and 21-2 having impedance matching circuits and added by adder 22. The input terminal 20-3 is connected to the second surface coil 2 (see FIG. 1), and the NMR signal received at the input terminal 20-3 is converted to a preamplifier 21 having an impedance matching circuit.
-3 is amplified. Adder 22 and preamplifier 21-
3 are phase shifters 23-1 and 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 an optimum addition condition;
After passing through 24-2, the quadrature phase detectors 25-1, 25
-2, and is converted into a digital signal (detection data) by the A / D converters 26-1 and 26-2, and guided to the computer 27. Each of the detection data led to the computer 27 is a computer 2
7 is temporarily stored in an internal storage device (not shown), and is synthesized on an image at the time of image reconstruction, thereby enabling signal synthesis that makes the best use of the amount of information. In this embodiment, the NMR signals are added by the adder 22, but the adder is not used, and the phase shifter, the attenuator, the quadrature phase detector,
The same operation can be performed by using two A / D converters. In this case, the sensitivity (S / N) is high, and the sensitivity distribution on the image is controlled so that the sensitivity uniformity is excellent.
And the S / N can be further improved.

[0013]

As described above in detail, according to the present invention, 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. Is configured to simultaneously obtain information from the surface coil and the second surface coil, so that the S / N is improved as compared with the conventional local imaging probe, and a probe for a nuclear magnetic resonance apparatus capable of obtaining a high quality image. And a remarkable effect that a receiving system using the same can be realized.

[Brief description of the drawings]

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

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

FIG. 3 is a view showing another embodiment of the first surface coil in the embodiment of FIG. 1;

FIG. 4 is a diagram showing a sensitivity distribution of the probe for a nuclear magnetic resonance apparatus shown in the embodiment of FIG. 3;

FIG. 5 is a view showing still another embodiment of the first surface coil in the embodiment of FIG. 1;

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

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

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

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

[Explanation of symbols]

DESCRIPTION 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 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 ... adders, 23-1, 23-2 ... phase shifters, 24-1, 24-2 ... attenuators, 25,
25-1, 25-2 ... quadrature phase detector, 26, 26-
1, 26-2: A / D converter, 27: Computer.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Etsuji Yamamoto 1-280 Higashi Koikebo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory of Hitachi, Ltd. (56) References JP-A 1-242054 (JP, A) JP-A-249043 (JP, A) JP-A-63-234957 (JP, A) JP-A-4-180733 (JP, A) JP-A-64-17636 (JP, A) (58) Fields investigated (Int. . ^7, DB name) A61B 5/055

Claims (2)

(57) [Claims] A plurality of unit surface coils are provided in each unit surface coil.
The minimum mutual coupling between adjacent unit surface coils.
Arranged on the same plane so that they overlap each other
A base for holding a first surface coil composed of a phased array coil; and an orthogonal portion for holding a second surface coil in a direction orthogonal to the surface of the base, and irradiating a high-frequency magnetic field to cover the base. A receiving system using a nuclear magnetic resonance apparatus probe that performs at least one of excitation of a nuclear spin of a sample and detection of a nuclear magnetic resonance signal from the nuclear spin of the subject.
And the receiving system is provided from the first and second surface coils.
Output to the addition condition corresponding to the imaging part of the subject.
After adjusting the phase difference and level difference, add and detect
A receiving system comprising a cross-phase detector. 2. A method according to claim 1, wherein a plurality of unit surface coils are provided in each unit surface coil.
The minimum mutual coupling between adjacent unit surface coils.
Arranged on the same plane so that they overlap each other
A first surface coil composed of a phased array coil
A base for holding the
A rectangular section for holding the surface coil of
To excite the nuclear spin of the subject, and
At least one of detection of nuclear magnetic resonance signals from nuclear spins
System using a probe for nuclear magnetic resonance
And the receiving system is provided from the first and second surface coils.
Output corresponding to the imaging region of the subject
Detect after adjusting the phase difference and level difference to the addition condition
A quadrature detector and the first and second surface coils
Storage device for storing data independently detected
And synthesizing the data on the image when reconstructing the image.
A receiving system characterized in that: