JPH0889492A - Sat setting and sat setting system - Google Patents

Abstract

PURPOSE: To provide a SAT setting system capable of easily setting presaturation by displaying an image as an original image and designating an area to perform presaturation (SAT) on the image by graphically inputting referring to the displayed image. CONSTITUTION: In an MRI instrument, a gate modulation circuit 7 is controlled according to a sequence stored in a memory circuit 3, and RF pulses generated at an RF transmitting circuit 6 are modulated to be added to a transmitting coil of a magnet assembly 5 from an RF power amplifier 8. NMR signals obtained at a receiving coil is inputted into a computer 2 via a phase detector 10, an AD transformer 11, etc., to display a rearranged image on a display 12. This system is composed so that a graphic SAT button on the display screen can be operated by operation of a mouse, a track ball, etc., on an operation table 13 to move into the input mode of the graphic SAT by SAT button operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to presaturation of a magnetic resonance imaging (MRI) apparatus.
on, hereinafter simply referred to as SAT. The present invention relates to a setting method and a SAT setting device, and more particularly to a SAT setting method and a SAT setting device capable of graphic input of SAT.

[0002]

2. Description of the Related Art An MRI apparatus measures the density distribution, relaxation time distribution, etc. of nuclear spins at a desired examination site in a subject by utilizing the nuclear magnetic resonance phenomenon, and the cross section of the subject is determined from the measured data. The image is displayed.

Nuclear spins of a subject placed in a uniform and strong static magnetic field generator perform precession around the direction of the static magnetic field at a frequency (Larmor frequency) determined by the strength of the static magnetic field. Therefore, when a high frequency pulse having a frequency equal to this Larmor frequency is irradiated from the outside, spins are excited and transition to a high energy state. This is called a nuclear magnetic resonance phenomenon. When the irradiation of the high frequency pulse is stopped, the spin returns to the original low energy state with a time constant corresponding to each state, and at this time, the electromagnetic wave is radiated to the outside. A high-frequency receiver coil (R
F coil) to detect. At this time, a triaxial gradient magnetic field is applied to the static magnetic field space for the purpose of adding position information to the space. As a result, position information in the space can be captured as frequency information.

By the way, in order to alleviate the artifacts from the peripheral region other than the scan region and the region of interest, such a peripheral region is set as a saturation region, and a presaturation (SAT) pulse is applied to excite it. Is being carried out.

The SAT setting will be described with reference to the drawings. FIG. 13 is an explanatory diagram for explaining the SAT setting in the FOV (Field Of View) direction (a plane parallel to the FOV portion of the image of the subject (hereinafter referred to as an image FOV)). For example, it is assumed that FIG. 13 shows a part of the cross section of the abdomen of the subject.

When setting the SAT, the image FOV portion of the subject is displayed as the original image on the display device of the operator console (solid line portion in FIG. 13). This Figure 1
The area of the image FOV in the center of 3 is the area where the tomographic image as the original image is actually displayed, and the operator inputs numerical values to set the SAT area around the area of this image FOV (upper, lower, left, and right). To do.

For example, an image of the subject is displayed in the area of the image FOV in FIG. A scale is displayed on such a display screen, and the size of the image FOV is read on the screen.

Then, referring to the read result, the interval (Slab Location: ~) from the end of the image FOV to the end of the SAT for the SAT (broken line portion in FIG. 13) of each part (upper, lower, left and right of the image FOV), Assuming the thickness of SAT (Slab Thickness: ′ to ′), the operator performs calculation based on a predetermined calculation method, and obtains the numerical value of each part.

Similarly, an image in the slice direction is displayed, and the SAT in the slice direction is set by referring to the screen. For example, in FIG. 14, an image of the subject in the head-feet direction is displayed for setting the SAT in the slice direction, and the slice position (solid line portion in FIG. 14) is displayed therein. A scale is displayed on such a display screen and the slice position, thickness, etc. are read from the screen.

Then, referring to the read result, the distance from the end of the slice to the end of the SAT (Slab Location :, SAT) of each part (Head direction and Feet direction of the slice position) ), SAT thickness (Slab Thickness: ′, ′) is assumed, and the operator performs calculation based on a predetermined calculation method to obtain the numerical values of each part.

Then, the SAT spacing (-) and the SAT thickness ('-
Input the numerical value of ') via a numerical input device such as a keyboard. For example, an input screen as shown in FIG. 15 is displayed, and the operator sequentially inputs numerical results obtained by calculation. Here, SA of each part of FIG. 13 and FIG.
In order to clarify the relationship between the interval of T (~) and the thickness of SAT ('~') and the input item of FIG. 15, each input item in the numerical input screen corresponds to the corresponding number of each part of FIGS. 13 and 14. Is attached. Therefore, assuming the SAT area shown by the broken lines in FIGS. 13 and 14, the numerical value thereof is calculated, and the numerical value is input from the numerical value input device to the part of the input screen of FIG.

Since the above SAT setting is relatively determined with reference to the FOV end and the slice end, the FOV
It is called Relative SAT.

[0013]

In the case of inputting numerical values as described above, the size of the image FOV or slice on the screen,
It is necessary to read the thickness and then calculate using the read numerical values, which is a troublesome operation.

Further, the setting of the SAT when changing the position of the slice to an arbitrary angle or when performing slices having a plurality of different angles has a drawback that the calculation becomes more troublesome.

The present invention has been made in view of the above points, and a first object of the present invention is to enable SA to be easily set.
It is to realize a T setting method and a SAT setting device. A second object is to realize a SAT setting method and a SAT setting device that can efficiently use SAT setting data.

[0016]

A first means for solving the above problems is to display an image as an original image, refer to the displayed image, and perform presaturation (SAT) on this image. A SAT setting method is characterized in that a SAT is set by designating an area by graphic input.

The second means for solving the above-mentioned problems is MR.
A SAT setting device for setting a presaturation (SAT) in the device I, and a display unit for displaying an image as an original image and a graphic using a pointing device on a display screen using the image displayed on the display unit. The SAT setting device further comprises setting means for setting the SAT by inputting.

A third means for solving the above problems is MR.
A SAT setting device for setting a presaturation (SAT) in a device I, which is a display unit for displaying an image as an original image, and a graphic using a pointing device on a display screen using the image displayed on the display unit. A setting means for setting the SAT by input and a setting value of the SAT set by the graphic input by the setting means are converted into numerical data, and an image is obtained from the data obtained by executing the scan based on the setting value of the SAT. SA in association with the processing means for generating and the image obtained by scanning based on the setting of SAT
A SAT setting device comprising: a data storage unit for storing numerical data of T.

[0019]

In the SAT setting method which is the first means for solving the problem, the image displayed as the original image is displayed, and the area for executing the SAT is set by graphic input on this display screen. .

In the SAT setting device which is the second means for solving the problems, the image displayed on the display means is used as the original image, and the graphic input is performed by using the pointing device on the display screen through the setting means. S
AT is set.

In the SAT setting device, which is the third means for solving the problem, an image displayed on the display means is used as an original image, and a graphic input is carried out using a pointing device on the display screen through the setting means. S
The AT is set, the set value of the SAT that has been set is converted into numerical data by the processing means, and scanning is performed based on the setting of the SAT, and the numerical data of the SAT is associated with the image obtained by the processing means. Is stored by the storage means.

[0022]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration diagram showing a configuration of a main part of a SAT setting device according to an embodiment of the present invention.

In FIG. 1, the MRI apparatus 1 realizes the SAT setting method of an embodiment of the present invention, and also constitutes the SAT setting apparatus of an embodiment of the present invention. Based on the instruction from the console 13, the computer 2
The overall operation of the RI apparatus 1 is controlled. The sequence storage circuit 3 operates the gradient magnetic field drive circuit 4 based on the stored sequence to generate a static magnetic field and a gradient magnetic field using the static magnetic field coil and the gradient magnetic field coil of the magnet assembly 5. Further, the sequence storage circuit 3 controls the gate modulation circuit 7, modulates the RF pulse generated by the RF transmission circuit 6 into a predetermined waveform, and applies the RF pulse to the transmission coil of the magnet assembly 5 from the RF power amplifier 8.

The NMR signal (for example, echo signal) obtained by the receiving coil of the magnet assembly 5 is input to the phase detector 10 via the preamplifier 9. The phase detector 10 phase-detects the reception signal output of the preamplifier 5 using the output of the RF oscillation circuit 9 as a reference signal. The output signal of the phase detector 10 is converted into a digital signal in the AD converter 11 and input to the computer 2. The result (reconstructed image) processed by the computer 2 is displayed as an image on the display device 12.

FIG. 2 shows the operating state of the SAT setting device described above.
That is, it is a flowchart showing the procedure of the SAT setting method. The operation will be described with reference to FIG. Console 13
The graphic SAT button (or the icon indicating the input of the graphic SAT) on the display screen of the display device 12 is operated via the pointing device (mouse, trackball, etc.) or key arranged in the graphic SAT. The input mode is entered (step in FIG. 2). It should be noted that, in addition to the buttons and icons on the display screen, operations such as selection buttons and selection switches of various input devices similarly shift to the input mode of the graphic SAT.

In the present embodiment, the graphic SA
T means that a specific position of the SAT area on the display screen is set on the display screen by a pointing device, and at least a part of the SAT settings (for example, any one of the SAT areas is set). Setting the area or any one of the items in one area) is also included.

When the input mode of the graphic SAT is entered, the image of the subject is displayed as the original image (step in FIG. 2). So that it is superimposed on this original image,
Two parallel lines are displayed as the SAT setting line. In the initial state, near the center of the screen, a predetermined interval (SAT thickness)
Then, the SAT setting line is displayed vertically. This state is shown in FIG. Further, a + -marked cursor is displayed near the center of the two SAT setting lines, and the position of the SAT setting line can be moved by operating the pointing device.

At the same time, a screen as shown in FIG. 4 is displayed as an auxiliary screen for SAT setting, which can be used as an input screen for inputting numerical values and a help screen for key operation.

A specific example of SAT setting will be described below with reference to an example of key operation shown on the auxiliary screen of FIG. However, the allocation of the key operation is merely an example, and other key operations are possible.

For example, by moving a cursor (a cross (+) in the center of FIG. 3) on the display screen with a pointing device such as a trackball or a mouse arranged on the console 13, as shown in FIG. The position of the SAT setting line can be changed.

Further, the SAT thickness can be changed as shown in FIG. 6 by inputting numerical values using a key input device arranged on the console 13. In such a case, the Thic of FIG.
A numerical value is displayed in the input item of hness, and S of FIG. 6 is displayed.
The AT thickness also changes.

By pressing the cursor movement key for a certain period of time or more, the SAT setting line can be rotated at an arbitrary angle with the center position (+ mark) of the SAT setting line as the rotation center, as shown in FIG. it can. Further, as shown in the auxiliary screen of FIG. 4, by pressing the “.” Key, it is possible to change the position of the display cursor to a right angle such as 0 ° / 90 °.

By operating a predetermined key, it is possible to return to the previous setting state (Prior Sat) and invalidate the latest setting. Then, a key for confirmation such as a key input section on the operation console 13 (Ente
The SAT setting is confirmed by pressing the r key, etc.).
In this way, when one item is set and confirmed, the next setting item becomes the input state. In this way, the SAT is set at an arbitrary position while referring to the original image on the display screen. Also, pressing the END key ends the SAT setting (step in FIG. 2).

When the SAT setting is completed, the computer 2 calculates the data of each item from the setting by the graphic SAT, and gives an instruction to the sequence storage circuit 3 as the same data as in the case of inputting a numerical value. The data of each item is displayed as numerical values in (a) and (c) of the screen shown in FIG.

In the screen shown as an example in FIG.
(A) is a graphic / numerical combination item, and (b)
Is an item dedicated to numerical values, and (c) is an item dedicated to graphics. That is, the screen shown in FIG. 8 assumes a system in which numerical input and graphic input can be used together depending on the ease of input. However, it is of course possible to dedicate it to graphic input, and in such a case, there is no item for inputting numerical values.

The relationship between each item in FIG. 8 and the SAT is shown in FIG.
And shown in FIG. That is, for each item in FIG. 8, the distance from the edge of the image FOV to the edge of the SAT (FOVoffset: to), the thickness of the SAT (Slab Thicknes
s: '~'), SAT position (Absolute offset:
"~") Is as shown in FIGS. 9 and 10. Further, the tilt (Tilt) in FIG. 8 means the tilt (tilt angle) of the SAT when performing a slice having a tilt. Here, LR, AP, and HF are tilts in the left-right direction and vertical (Anterior-Posteri) directions, respectively.
It means the inclination in the or direction and the inclination in the head-feet direction.

The above completes the graphic SAT setting, but it is also possible to display a different original image and repeat the graphic SAT setting again (step → in FIG. 2). For example, the graphic SAT setting can be repeated again by rotating the original image at an arbitrary angle.

Then, when the graphic SAT setting is completed, the scan is executed (step in FIG. 2). In this scan, a SAT pulse is applied and excitation is performed in the area defined by the graphic SAT setting.

As described in detail above, by performing the SAT setting by the graphic, the setting operation becomes extremely simple. Further, even when the original image is rotated, no troublesome work occurs.

The image created after the scan is completed is stored in the storage device 14. At this time, the graphic SAT setting data described above is stored in association with the image. For example, FIGS. 11 (a) and 11 (b)
It is stored in the data format as shown in.

Here, FIG. 11A shows an Absolute.
This is the case when SAT is specified, and FIG. 11B shows FOV.
The data format when Relative SAT is designated is shown. Where Absolute SAT
Means that the coordinates as an absolute value are specified by the graphic SAT setting according to the present invention, and the FOV
Relative SAT means a case of a conventional method in which coordinates are relatively designated by numerical input with reference to the FOV end and the slice end.

Further, in FIG. 11A, "H: P
“S” is the position of the SAT in the head direction (position: Ab
solute offset, which has a sign of ± because it is an absolute value). Similarly, F, A, P, L, and R are the feet (Feet), upper (Anterior), lower (Posterior), and left (Lef), respectively.
t) and each item in the right direction.
“TH” is the SAT thickness (Slab thicknes) in the head direction.
s), “LR”, “AP”, and “HF” are the above-mentioned LR, A
The tilt angles in the P and HF directions are shown. And in the figure
The set numerical value is stored in the part indicated by ****. Further, in FIG. 11B, H, F, A, P, L, and R have the same meanings as in FIG. 11A, and in this case, since they are relative values, there is no sign of ± Accordingly, the data is stored together with the signs of I and O indicating the inside or the outside.

Then, as shown in FIG. 12, when the surgery is performed after setting the graphic SAT (steps from FIG. 12) and scanning (step from FIG. 12), the scan is performed again under the same conditions as before the surgery. There are times when you want to do it.

In such a case, it is almost impossible to set the graphic SAT under the same condition again using the pointing device. Therefore, the graphic SAT setting data stored in association with the image data is read and treated in the same manner as the numerical input data in the conventional case,
It becomes possible to execute a scan (step in FIG. 12) under the same conditions as the previous scan.

As described in detail above, the SAT area is graphically set on the graphic screen and scanning is performed, and the graphic SAT setting data is stored in a state related to the image thus obtained. By doing so, it becomes possible to efficiently use the setting data of the graphic SAT and execute a scan with good reproducibility.

[0046]

As described in detail above, since the SAT setting is performed graphically, the setting operation becomes extremely easy, and even when the original image is rotated, some troublesome work is required. It is possible to realize a SAT setting method and a SAT setting device that can be easily set without the above.

In addition, the graphic SAT is set and S is associated with the image obtained by scanning.
By storing the AT setting data in association with each other, it is possible to efficiently use the setting data of the graphic SAT and perform reproducible scanning a plurality of times.
An AT setting method and a SAT setting device can be realized.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a configuration example of a SAT setting device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a procedure of a SAT setting method according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing an example of a display screen at the time of setting by graphic SAT setting according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram showing an example of a display screen according to a graphic SAT setting according to an embodiment of the present invention.

FIG. 5 is an explanatory diagram showing an example of a display screen at the time of setting by the graphic SAT setting according to the embodiment of the present invention.

FIG. 6 is an explanatory diagram showing an example of a display screen at the time of setting by graphic SAT setting according to an embodiment of the present invention.

FIG. 7 is an explanatory diagram showing an example of a display screen at the time of setting by graphic SAT setting according to an embodiment of the present invention.

FIG. 8 is an explanatory diagram showing an example of a display screen of setting data by graphic SAT setting according to an embodiment of the present invention.

9 is an explanatory diagram for explaining a positional relationship of each item in FIG.

FIG. 10 is an explanatory diagram for explaining the positional relationship of each item in FIG.

FIG. 11 is an explanatory diagram showing an example of a data format at the time of storing the setting data obtained by the graphic SAT setting according to the embodiment of the present invention.

FIG. 12 is a flowchart showing a procedure of a SAT setting method according to another embodiment of the present invention.

FIG. 13 is an explanatory diagram showing a conventional SAT setting.

FIG. 14 is an explanatory diagram showing a state of conventional SAT setting.

FIG. 15 is an explanatory diagram showing a state of conventional SAT setting by inputting numerical values.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 MRI apparatus 2 Computer 3 Sequence storage circuit 4 Gradient magnetic field drive circuit 5 Magnet assembly 6 RF oscillation circuit 7 Gate modulation circuit 8 RF power amplifier 9 Preamplifier 10 Phase detector 11 AD converter 12 Display device 13 Operation console 14 Storage device

Claims (3)

[Claims] 1. A SAT is set by displaying an image as an original image, referring to the displayed image, and designating an area on which the presaturation (SAT) is to be performed by graphic input. Characteristic SAT setting method. 2. A SAT setting device for setting a presaturation (SAT) in an MRI apparatus, comprising: display means for displaying an image as an original image; and pointing on a display screen using the image displayed on the display means. A SAT setting device comprising: a setting unit configured to set a SAT by graphic input using a device. 3. A SAT setting device for setting a presaturation (SAT) in an MRI device, the display device displaying an image as an original image, and pointing on a display screen using the image displayed on the display device. Setting means for setting SAT by graphic input using a device and SA set by graphic input by the setting means
A processing means for converting the set value of T into numerical data and performing an scan based on the set value of SAT to generate an image, and an image obtained by performing the scan based on the setting of SAT. And a data storage unit for storing numerical data of SAT in a state related to the SAT setting device.