JPH07284486A - Mri imaging method using body insertion coil and mri apparatus - Google Patents

Abstract

PURPOSE:To accurately perform local MR imaging using a body insertion coil. CONSTITUTION:A body insertion coil is inserted in the body of an examainee (step D1) and the estimation position of the body insertion coil is set to the parameter of an imaging sequence and a whole body coil is used to perform imaging (step D2) and the actual position of the body insertion coil is detected from the obtained MR image (step D3). Next, the actual position is set to the parameter of the imaging sequence and the body insertion coil is used at least in reception to perform imaging (step D4) and a local MR image is obtained. Therefore, only by the labor of MR imaging performed twice, local MR imaging using the body insertion coil can be accurately performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an MR (Magnetic Resonance) imaging method and MRI using a coil inserted in the body.
The present invention relates to a (Magnetic Resonance Imaging) apparatus, and more particularly to an MR imaging method and an MRI apparatus capable of accurately performing local MR imaging using a coil inserted in the body.

[0002]

2. Description of the Related Art FIG. 10 is an explanatory diagram showing a state in which local MR imaging is performed using a surface coil SC. The surface coil SC is placed in the imaging region of the subject H, the position P of the surface coil SC is used as a parameter of the imaging sequence, and the whole body coil BC is used as the transmission coil to excite the imaging visual field F centered on the position P. An NMR signal is received by the surface coil SC. Then, a local MR image is acquired from the received data.
The surface coil SC may be used for transmission and reception.

FIG. 11 is an explanatory diagram showing a state in which local MR imaging is carried out using the body-insertion coil IC. Subject H
The body insertion coil IC is inserted into the body of the body, and the estimated position Pg of the body insertion coil IC is used as a parameter of the imaging sequence, and the whole body coil BC is used as a transmission coil to excite the imaging field of view Fg centered on the estimated position Pg. , The NMR signal is received by the coil IC inserted in the body. Then, a local MR image is acquired from the received data. The body insertion coil IC is, for example, a rectangular coil of 1 cm × 4 cm. In this case, the spatial area (imaging volume) where the MR image can be acquired is a spatial area of 2 cm to 3 cm near the coil surface of the body insertion coil IC.

[0004]

When performing local MR imaging, as shown in FIG. 10, a surface coil SC is used.
When is used, the actual position P of the surface coil SC can be easily confirmed.
R imaging is performed. On the other hand, when the body insertion coil IC is used as shown in FIG. 11, since the body insertion coil IC is not visible, the actual position is unknown, and the estimated position Pg is set to perform MR imaging. However, as shown in FIG. 12, the estimated position Pg of the body insertion coil IC is
When r is different from r, there is a problem that MR imaging cannot be performed accurately. In addition, the estimated position Pg is modified so that the MR
If the imaging is re-executed many times, there is a problem that the MR imaging is troublesome many times. In addition, there is a problem that the restraint time of the subject H becomes long, a large burden is placed on the subject H, and the throughput is reduced. Therefore, an object of the present invention is to provide an MR imaging method and an MRI apparatus capable of accurately performing local MR imaging using an in-body inserted coil only with the trouble of performing two MR imagings.

[0005]

According to a first aspect of the present invention, an internal insertion coil is inserted into the body of a subject, and the estimated position of the internal insertion coil is used as a parameter of an imaging sequence and other than the internal insertion coil. The actual position of the body-inserted coil is detected from the obtained MR image, the actual position is used as a parameter of the imaging sequence, and the body-inserted coil is used for at least reception to perform an image pickup to obtain a local MR. Provided is an MR imaging method using an in-body inserted coil, which is characterized by obtaining an image.

According to a second aspect, the present invention is a positioning image pickup means for taking an estimated position of an in-body insertion coil inserted in the body of a subject as a parameter of an imaging sequence and imaging using a coil other than the in-body insertion coil. Actual position setting means for setting the actual position of the body insertion coil detected based on the MR image obtained by the positioning image pickup means, and the actual position as a parameter of the imaging sequence, and using the body insertion coil for at least reception. Provided is an MRI apparatus comprising: an inspection image pickup unit that picks up an image to obtain a local MR image. MR with the above configuration
In the device I, the coils other than the body insertion coil are
It is preferably a whole body coil. Further, in the MRI apparatus having the above-mentioned configuration, it is preferable that the body insertion coil has a position mark made of a material serving as an NMR signal source such as an aqueous solution of a contrast medium or tetramethylsilane.

[0007]

In the MR imaging method and MRI apparatus using the body insertion coil of the present invention, after inserting the body insertion coil into the body of the subject, first, the estimated position of the body insertion coil is used as a parameter of the imaging sequence and An MR image is obtained by imaging using a coil other than the insertion coil. Next, the actual position of the body insertion coil is detected from the obtained MR image, and the actual position is used as a parameter of the imaging sequence, and the body insertion coil is used for at least reception to perform imaging to obtain a local MR image. As described above, first, the positioning imaging is performed to detect the actual position of the body insertion coil, and the actual inspection imaging is performed using the actual position. Therefore, the body insertion coil can be used with only two MR imaging steps. The local MR imaging can be performed accurately. Further, the restraint time of the subject H can be shortened, the burden on the subject H can be reduced, and the throughput can be improved.

If a whole body coil is used as the coil other than the body insertion coil, a wide range can be imaged, so that the actual position of the body insertion coil can be easily detected. When the body insertion coil has a position mark made of an NMR signal source material such as a contrast agent aqueous solution or tetramethylsilane, the body insertion coil is visualized as a high signal on the MR image obtained by positioning imaging. Therefore, it becomes easy to detect the actual position of the body insertion coil.

[0009]

The present invention will be described in more detail with reference to the embodiments shown in the drawings. The present invention is not limited to this. FIG. 1 is a block diagram of an embodiment of the MRI apparatus of the present invention. In this MRI apparatus 100, the magnet assembly 1 has a space portion (hole) for inserting a subject therein, and a static magnetic field for applying a constant static magnetic field to the subject so as to surround this space portion. A coil, a gradient magnetic field coil for generating a gradient magnetic field (the gradient coil has a read axis, a phase axis, and a slice axis coil), and an RF pulse for exciting spins of nuclei in a subject. A transmitting coil to be given and a receiving coil for detecting an NMR signal from the subject are arranged. The static magnetic field coil, the gradient magnetic field coil, and the whole body coil are respectively the main magnetic field power supply 2, the gradient magnetic field drive circuit 3, and the RF.
It is connected to the power amplifier 4 and the preamplifier 5.

The sequence storage circuit 8 operates the gradient magnetic field drive circuit 3 based on the stored data acquisition pulse sequence in accordance with a command from the computer 7 to generate a gradient magnetic field from the gradient magnetic field coil of the magnet assembly 1. At the same time, the gate modulation circuit 9 is operated to modulate the high frequency output signal of the RF oscillating circuit 10 into a pulsed signal having a predetermined timing and a predetermined envelope, which is used as an RF pulse for RF.
In addition to the power amplifier 4, power is amplified by the RF power amplifier 4 and then applied to the transmission coil of the magnet assembly 1 to selectively excite a target region.

The preamplifier 5 includes a magnet assembly 1
The NMR signal from the subject detected by the receiving coil is amplified and input to the phase detector 12. The phase detector 12 is
The output of the RF oscillation circuit 10 is used as a reference signal, and the preamplifier 5
The NMR signal from is phase-detected and given to the A / D converter 11. The A / D converter 11 converts the analog signal after phase detection into a digital signal and inputs it to the computer 7.
The computer 7 performs an image reconstruction operation on the digital signal from the A / D converter 11 to generate an image (proton density image) of a target area. This image is displayed on the display device 6. Further, the computer 7 is responsible for overall control such as receiving information input from the console 13.

In normal MR imaging, the whole body coil functions as the transmitting coil and the receiving coil. Also,
In local MR imaging, a coil for the whole body functions as the transmitting coil, and a surface coil or a coil for insertion into the body functions as the receiving coil. Alternatively, a surface coil or a coil for insertion into the body works as the transmitting coil and the receiving coil.

FIG. 2 is a flowchart of the MR imaging method using the body insertion coil in the MRI apparatus 100. In Step D1, as shown in FIG. 3, the body insertion coil IC is inserted into the body of the subject H. The body-inserted coil IC may be an endoscope type having an optical fiber. In this case, there is an advantage that the in-body insertion coil IC can be inserted into a desired position of the affected area or the like while looking at the endoscope. In step D2, the body insertion coil IC shown in FIG.
Is used as a parameter of the imaging sequence, the whole body coil BC is used as a transmission coil to excite the imaging field of view Fg centered on the estimated position Pg, and the whole body coil BC is used as a reception coil to receive an NMR signal. The MR image Si (i = 1, 2,
...) is obtained. The parameters of the imaging sequence include, in addition to the estimated position Pg, the imaging field of view Fg, the slice position in the X direction (a plate-shaped space area corresponding to the MR image Si), and the type of the imaging sequence (for example, “Fast Spoiled”).
Gradient Acquisition in Stady State ”etc.) In step D3, the MR image Si in which the body insertion coil IC is depicted is searched, and the image position of the body insertion coil IC on the MR image Si is searched. The actual position of the body insertion coil IC is detected from the normal body insertion coil IC, which normally has a blocking circuit B for blocking electromagnetic coupling with the whole body coil BC as shown in FIG. As shown in FIG. 5, it is rendered as a non-signal portion on the MR image Si.
The position of the body insertion coil IC on the MR image Si can be known from this non-signal portion. Further, the center of the MR image Si is the center of the imaging field of view Fg and is the estimated position Pg. Therefore, by combining the two, the actual position Pr of the body insertion coil IC can be detected. In step D4, as shown in FIG. 6, the actual position Pr of the body insertion coil IC is used as a parameter of the imaging sequence, the whole body coil BC is used as a transmission coil, and the body insertion coil IC is used as a reception coil to perform local MR imaging. To do. Alternatively, local MR imaging is performed by using the insertion coil IC in the body as a transmission coil and a reception coil. According to the MRI apparatus 100 described above, the M
It becomes possible to accurately perform local MR imaging using the body-inserted coil IC with only the labor of R imaging.
In addition, in the imaging in step D2, a plurality of MR images Si
However, if the parameters are input, the plurality of MR images Si are automatically picked up. Therefore, the step D2 needs only one time.

As another embodiment, a body insertion coil IC having no blocking circuit as shown in FIG. 7 is used, or an incomplete blocking circuit having a blocking circuit (coil for a whole body to a certain extent is used. An example is a case of using an in-body inserted coil IC having a blocking circuit in which electromagnetic coupling with BC remains. In these cases, since the body insertion coil IC is visualized on the MR image Si with a high signal, it becomes easy to detect the actual position of the body insertion coil IC. Since the body-inserted coil IC is very small, even if there is electromagnetic coupling with the whole-body coil BC, no particular trouble will occur.

An in-body inserted coil IC having a contrast medium pipe Z as shown in FIG. 8 may be used. in this case,
At the time of positioning imaging (step D2), the contrast agent pipe Z is filled with the contrast agent aqueous solution. Then. Since the contrast agent pipe Z is drawn at a high signal on the MR image Si, it becomes easy to detect the actual position of the body insertion coil IC. On the other hand, at the time of inspection imaging (step D4), the contrast medium aqueous solution is drawn out from the contrast medium pipe Z so that unnecessary NMR signals are not emitted.

Alternatively, an in-body inserted coil IC having a position mark W of tetramethylsilane as shown in FIG. 9 may be used. In this case, at the time of positioning imaging (step D2), excitation is performed in accordance with the frequency of tetramethylsilane different from the resonance frequency of protons, and reception is performed. Then, since the position mark W is drawn on the MR image Si with a high signal, it becomes easy to detect the actual position of the body insertion coil IC. On the other hand, during inspection imaging (step D4), the position mark W is excited and received in accordance with the frequency of the proton so that the position mark W is not drawn on the MR image Si.

[0017]

[Effects of the Invention] MR using the body insertion coil of the present invention
According to the imaging method and the MRI apparatus, the position of the body-inserted coil is actually measured, and MR imaging is performed according to the actual position. Therefore, local MR imaging using the body-inserted coil can be performed with only two labors of MR imaging. Can be done accurately. Further, the restraint time of the subject H can be shortened, the burden on the subject H can be reduced, and the throughput can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an MRI apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating the operation of the MRI apparatus of FIG.

FIG. 3 is an explanatory diagram of positioning imaging.

FIG. 4 is an explanatory diagram of a body insertion coil and a blocking circuit.

FIG. 5 is an exemplary diagram of an MR image by positioning imaging.

FIG. 6 is an explanatory diagram of inspection imaging.

FIG. 7 is an explanatory view of a body insertion coil having no blocking circuit.

FIG. 8 is an explanatory view of a body insertion coil having a contrast agent pipe.

FIG. 9 is an explanatory diagram of a body insertion coil having a position mark.

FIG. 10 is an explanatory diagram of imaging using a surface coil.

FIG. 11 is an explanatory diagram of imaging using a body insertion coil.

FIG. 12 is another explanatory diagram of imaging using the coil inserted in the body.

[Explanation of symbols]

 100 MR device 1 Magnet assembly 3 Gradient magnetic field drive circuit 7 Computer 8 Sequence storage circuit 9 Gate modulation circuit 10 RF oscillation circuit 13 Operation console BC Whole body coil IC Internal insertion coil Pg Estimated position Pr Actual position H Subject B Blocking circuit Z Contrast imaging Agent pipe W position mark

Claims (4)

[Claims] 1. An MR image obtained by inserting an intracorporeal insertion coil into the body of a subject, using the estimated position of the intracorporeal insertion coil as a parameter of an imaging sequence, and imaging using a coil other than the intracorporeal insertion coil. The actual position of the body-inserted coil is detected, the actual position is used as a parameter of the imaging sequence, and the body-inserted coil is used for at least reception to perform image capturing to obtain a local MR image. MR imaging method. 2. Positioning imaging means for imaging using an estimated position of an in-body insertion coil inserted into the body of a subject as a parameter of an imaging sequence and using a coil other than the in-body insertion coil, and the positioning imaging means. MR
Actual position setting means for setting the actual position of the body insertion coil detected based on the image, and obtaining a local MR image by capturing an image using the body position as a parameter of the imaging sequence and using the body insertion coil at least for reception. An MRI apparatus comprising an inspection image pickup means. 3. The MRI apparatus according to claim 2,
The MRI apparatus, wherein the coils other than the body insertion coil are whole body coils. 4. The MRI according to claim 2 or 3.
In the apparatus, the body insertion coil has a position mark made of a material serving as an NMR signal source such as an aqueous solution of a contrast agent or tetramethylsilane.