JPH0435645A - Magnetic resonance imaging device - Google Patents

Abstract

PURPOSE:To realize a highly sensitive photograph by one or plural RF coils of selected ones, by providing a selecting means to select one or plural RF coils near the concerned area in an actual space. CONSTITUTION:A change-over circuit 8 which receives an instruction of a computer system 14 in a step S6 carries out a terminal changeover for selecting a single coil immediately below the recognized segment of line ROI. As to an axial section including the segment ROI set on the positioning image by the series of operations, its positioning is set to a magnetic field center FC by the movement of a roof, and a coil in which the area of an object P to be detected corresponding to the segment ROI is made as its data collection area is to be selected by the operation of the change-over circuit 8. As a result, as to the axial section including the concerned segment ROI, a circumstance in which a highly sensitive data collection is realized in a high even magnetic field is to be arranged. A prescanning is made in a step S7 to carry out the photograph, and the axial image is displayed on the image screen of a monitor.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to magnetic resonance (MR)
The present invention relates to a magnetic resonance imaging apparatus that can generate images by utilizing the phenomenon (sonance).

(Prior art) Magnetic resonance is a phenomenon in which an atomic nucleus with non-zero spin and magnetic moment placed in a static magnetic field resonantly absorbs and emits only electromagnetic waves of a specific frequency. The angular frequency ω shown in (ωo=2πν., o
; Larmor frequency) ν.

ω0−γHO Here, γ is the gyromagnetic ratio specific to the type of atomic nucleus,
Further, no is the static magnetic field strength.

An apparatus that performs biological diagnosis using the above-mentioned principle processes the electromagnetic waves of the same frequency as the above induced after the above-mentioned resonance absorption, and calculates the nuclear density, longitudinal relaxation time TI + transverse relaxation time T2. Diagnostic information that reflects magnetic resonance parameters such as flow and chemical shift, such as slice images of a subject, is obtained non-invasively.

Collecting diagnostic information using magnetic resonance can excite all parts of a subject placed in a static magnetic field and collect signals, but there are limitations in the equipment configuration and clinical limitations in imaging images. In response to the above requirements, actual devices excite a specific region and collect its signals.

In this case, the specific region to be imaged is generally a sliced region with a certain thickness;
Magnetic resonance signals (MR multiplied signals) of echo signals and FID signals from this slice site are collected by performing a data encoding process many times, and these data groups are subjected to image reconstruction processing using, for example, a two-dimensional Fourier transform method. By doing so, a tomographic image (slice image) of the specific slice region is generated.In addition to the tomographic image (slice image), a fluoroscopic image (scano image) or angioimage suitable for use as a positioning image, etc. You can also get images.

In such a device, a whole-body coil built into the gantry excites a wide area of the subject and collects signals, thereby obtaining a sagittal or coronal image or a scano image of a wide area. This enables positioning.

On the other hand, a method (multi-Surf Ace coil method) has been proposed in which a plurality of small, highly sensitive surface coils are embedded in the top plate of a bed to perform high-sensitivity imaging of localized areas. When this method is adopted, high-sensitivity imaging can be performed for the area near the selected surface coil, but it is not clear whether the area near the selected surface coil actually includes the region of interest to be diagnosed. , can only be confirmed after the photo is taken. That is, there is a problem in that it is difficult to accurately select a surface coil that includes a region of interest to be diagnosed.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a magnetic resonance imaging apparatus that can realize high-sensitivity imaging of a region of interest when employing a multi-Surface coil method.

[Configuration of the Invention (Means for Solving the Problem) In other words, the invention according to claim 1 provides a gantry capable of generating a magnetic field therein for causing a magnetic resonance phenomenon;
A bed that is installed close to this gantry and has a top plate that moves forward and backward into the gantry while placing a subject thereon, and a magnetic field for excitation related to magnetic resonance phenomena that is provided on the top plate of this bed. In a magnetic resonance imaging apparatus including a plurality of RF coils involved in at least one of generating and collecting magnetic resonance signals, a region of interest is set on a monitor that displays a reconstructed image based on the collected magnetic resonance signals. a setting means; a calculating means for calculating positional information in real space corresponding to the region of interest on the image set by the setting means; and selecting means for selecting one or more of the RF coils close to the region of interest.

The invention according to claim 2 also provides a gantry capable of generating a magnetic field for causing a magnetic resonance phenomenon inside the gantry, and a gantry that is installed in close proximity to the gantry and that moves forward and backward into the gantry while placing a subject thereon. A bed having a top plate, and a plurality of RF coils provided on the top plate of the bed and participating in at least one of the generation of an excitation magnetic field related to a magnetic resonance phenomenon and the collection of magnetic resonance signals. A magnetic resonance imaging apparatus comprising: a setting means for setting a region of interest on a monitor displaying a reconstructed image based on the collected magnetic resonance signals, and a region corresponding to the region of interest on the image set by the setting means. calculation means for calculating positional information in real space; and selection means for selecting one or more of the RF coils close to the region of interest in real space based on the positional information calculated by the calculation means. and a moving means for moving the top plate so that the region of interest in real space is located at the center of the magnetic field in the gantry based on the position information calculated by the calculating means. do.

(Function) According to the invention according to claim 1, simply by setting a region of interest in an image displayed on a monitor, one or more of the RF coils close to the region will be selected. High-sensitivity imaging is possible using the one or more selected RF coils.

Further, according to the invention according to claim 2, by simply setting a region of interest in an image displayed on a monitor, one or more of the RF coils close to the region are selected; Since it is located at the center of the magnetic field within the gantry, high-sensitivity imaging using the selected one or more RF coils is possible under favorable magnetic field conditions.

(Example) A magnetic resonance imaging apparatus according to the present invention will be described below with reference to the drawings. That is, as shown in FIG. 1, this device uses a static magnetic field coil or a permanent magnet (static A shim coil for magnetic field correction may be added.)1
, an x-, y-, and z-axis gradient magnetic field generating coil 2 for generating a gradient magnetic field for providing positional information of the induced site of the magnetic resonance signal, and a magnetic resonance signal ( A transmitting/receiving system for detecting the MR multiplied signal, for example, a whole body R consisting of a transmitting coil and a receiving coil.
The gantry 4 includes an F coil 3 therein.

In the subject introduction space of this gantry 4, the coil 1
, 2.degree. 3 generates a magnetic field for causing a magnetic resonance phenomenon, and in particular, a uniform magnetic field region DSV is generated at a portion located in the center of the figure.

On the other hand, a bed 5 is installed adjacent to the gantry 4.

This bed 5 has a top plate 6 that moves forward and backward into the gantry 4 while placing the subject P thereon. Further, as shown in FIG. 2, a multi-Surf Ace coil 7 is embedded in the top plate 6.

Further, as shown in FIG. 3, the multi-Surf Ace coil 7 can be selectively switched between a single coil or a plurality of coils by a switching circuit 8. That is, as shown in FIG. 3, when terminals a and b are selected by switching circuit 8, a single coil is formed with terminals a and b as both ends, and similarly when terminals a and c are selected by switching circuit 8, a single coil is formed with terminals a and b as both ends. A single coil is formed with ends a and c. That is, by selecting two or more terminals, it is possible to select a single coil or a plurality of coils in arbitrary positions and sizes. Furthermore, bed 5
An encoder 9 is provided to measure the position of the top plate 6, and feedback control regarding the movement of the top plate 6 is performed based on the output of the encoder 9.

On the other hand, this device includes a transmitter 1 that controls the transmission of RF pulses.
0, a receiver 11 that performs induced MR multiplied signal reception control, and in the embodiment of the present invention, when implementing the multi-surf ace coil system, the transmitter 10 is equipped with a whole-body RF
An excitation RF pulse is transmitted to the coil 3, and a receiver 11 receives magnetic resonance signals collected by the multi-surf ace coil 7. Of course, the transmitter 10 transmits excitation RF pulses to the multi-surf ace coil 7, and the receiver 11 receives magnetic resonance signals collected by the whole body RF coil 3. , both the transmitter 10 and the receiver 11 are equipped with a multi-surf ace coil 7.
It is also possible to use both of the whole body RF coil 3 as a transmitting/receiving coil.

Furthermore, this device includes a gradient magnetic field power supply 12 that performs excitation control of each of the gradient magnetic field generating coils 2 on the x, y, and z axes, and a pulse sequence for generating slice images and a pulse sequence for generating spectroscopy. The computer system 14 includes a sequencer 13 capable of controlling the sequencer 13, a computer system 14 that controls the sequencer 13, processes detection signals, and displays them, a monitor 15, and a console 16.

Next, the operation of this embodiment configured as described above will be explained with reference to the flowchart shown in FIG. Note that, prior to executing the process shown in FIG. 4, a positioning image is obtained by the multi-Surf Ace coil 7 or the whole-body RF coil 3, and is displayed on the screen 15A of the monitor 15, as shown in FIG. The display example shown in the figure is a sagittal image of the upper body of the subject P. Processing steps start for this positioning image SI, and in step S1, for example, R
Specify OI. In this case, an axial image including the line segment ROI will finally be photographed, and step S2 is executed to set the photographing area of the axial image. That is, in step S2, the field of view (FOV)
).

Next, in step S3, by determining the coordinates of the line segment ROI on the screen, the coordinates of the line segment ROI in real space are calculated. Note that there is a correspondence between the coordinates in real space and the coordinates on the image, and the computer system 14 knows this relationship in advance, and reconstructs the image using this correspondence. . Therefore, the computer system 14 calculates the distance from the magnetic field center FC of the line segment ROI based on the coordinate information of the line segment ROI in real space. This distance is the distance that the top plate 6 should move.

Next, in step S4, calculations for selecting a coil in the multi-Surf Ace coil 7 are performed. That is, since the position of the line segment ROI in real space is already known, the single coil located directly below the line segment ROI is recognized.

Next, in step S5, the bed 5 receives the command from the computer system 14 and moves the top 6 by the distance of the top movement. As a result, the line segment RO in real space
The position corresponding to I will coincide with the magnetic field center FC.

Next, in step S6, the switching circuit 8 receives a command from the computer system 14 and performs terminal switching to select the single coil directly below the line segment Rot recognized by the above-described operation.

Through the above series of operations, the positioning of the axial section including the line segment ROI set on the positioning image shown in FIG. Through this operation, a coil is selected whose data collection area is an area corresponding to the line segment ROI of the subject P. As a result, an environment has been prepared in which highly sensitive data collection under a highly uniform magnetic field can be achieved for the axial section including the line segment ROI. In this case, the line segment ROI is a region arbitrarily designated by the operator on the screen, and this region is automatically set to the optimal imaging conditions.

After the above settings are completed, the image is photographed by bliscanning in step S7, and the axial image shown in FIG. 6 is displayed on the screen of the monitor 16.

As described above, according to this embodiment, a desired area set on a positioning image can be photographed with high sensitivity using a surface coil selected in accordance with the area under highly uniform magnetic field conditions. becomes.

The present invention is not limited to the above-mentioned embodiments. For example, the present invention may be configured to perform at least one of the movement of the top plate 6 and the coil switching, and various modifications may be made without departing from the gist of the present invention. It can be implemented by

[Effects of the Invention] As described above, the invention according to claim 1 includes a setting means for setting a region of interest on a monitor that displays a reconstructed image based on collected magnetic resonance signals, and a region of interest set by the setting means. a calculation means for calculating positional information in real space corresponding to the region of interest on an image; and an RF coil located close to the region of interest in real space based on the positional information calculated by the calculation means. By having a selection means for selecting one or more of the RF coils, simply by setting a region of interest on the image displayed on the monitor, one or more of the RF coils close to the region can be selected. Therefore, high-sensitivity imaging is possible using the one or more selected RF coils.

In the invention according to claim 2, there is provided a setting means for setting a region of interest on a monitor displaying a reconstructed image based on the collected magnetic resonance signals, and a setting means for setting a region of interest on the image set by the setting means. a calculation means for calculating positional information in real space corresponding to the area, and selecting one or more RF coils close to the region of interest on the real space based on the positional information calculated by the calculation means. and a moving means for moving the top plate so that the region of interest in real space is located at the center of the magnetic field in the gantry based on the position information calculated by the calculation means. By simply setting a region of interest in an image displayed on a monitor, the R
One or more of the F coils are selected and the region is located at the center of the magnetic field within the gantry, so that
High-sensitivity imaging is possible using the selected one or more RF coils under favorable magnetic field conditions.

Therefore, according to the present invention, it is possible to provide a magnetic resonance imaging apparatus that can realize high-sensitivity imaging of a region of interest when employing the multi-Surface coil method.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an embodiment of the magnetic resonance imaging apparatus according to the present invention, FIG. 2 is a perspective view showing the configuration of a bed in the embodiment, and FIG. 3 is a multi-Surf Ace coil in the embodiment. FIG. 4 is a flowchart showing the operation of the same embodiment, FIG. 5 is a diagram showing a positioning image in the same embodiment, and FIG. 6 is a diagram showing a final photographed image. MA... Magnet assembly, 1... Static magnetic field coil, 2... Gradient magnetic field coil, 3... RF coil for whole body, 4... Gantry, 5... Bed, 6... Top plate , 7...Multi Surf Ace coil, 8...Switching circuit, 9...Encoder, 10...Transmitter, 11...
- Receiver, 12...Gradient magnetic field power supply, 13...Sequencer, 14...Computer system, 15...Monitor, 16...Console. Applicant's Representative Patent Attorney Takehiko Suzue Figure 3 Figure Figure Figure Figure

Claims (2)

[Claims] (1) A gantry capable of generating a magnetic field for causing a magnetic resonance phenomenon inside the gantry, and a bed that is installed close to the gantry and has a top plate that moves forward and backward into the gantry while placing the subject thereon. , a plurality of R's that are provided on the top plate of the bed and that are involved in at least one of the generation of an excitation magnetic field related to the magnetic resonance phenomenon and the collection of magnetic resonance signals.
In a magnetic resonance imaging apparatus including an F coil,
a setting means for setting a region of interest on a monitor displaying a reconstructed image based on the collected magnetic resonance signals; and position information in real space corresponding to the region of interest on the image set by the setting means. and a selection means for selecting one or more of the RF coils close to the region of interest in real space based on the position information calculated by the calculation means. magnetic resonance imaging equipment. (2) A gantry capable of generating a magnetic field therein to cause a magnetic resonance phenomenon, and a bed that is installed close to the gantry and has a top plate that moves forward and backward into the gantry while placing the subject thereon. , a plurality of R's that are provided on the top plate of the bed and that are involved in at least one of the generation of an excitation magnetic field related to the magnetic resonance phenomenon and the collection of magnetic resonance signals.
In a magnetic resonance imaging apparatus including an F coil,
a setting means for setting a region of interest on a monitor displaying a reconstructed image based on the collected magnetic resonance signals; and position information in real space corresponding to the region of interest on the image set by the setting means. calculation means for calculating, selection means for selecting one or more of the RF coils close to the region of interest in real space based on the position information calculated by the calculation means, and calculation means for calculating by the calculation means. a moving means for moving the top plate so that the region of interest in real space is located at the center of the magnetic field in the gantry based on the position information obtained.