JPH0620443B2 - MRI equipment - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to an MRI apparatus that obtains an image by using nuclear magnetic resonance (NMR).

[Prior art]

2. Description of the Related Art Conventionally, in an MRI apparatus, an imaging method (usually called multi-angle scanning) is performed in which a plurality of non-parallel slices are collectively collected at one time and data is acquired. This multi-angle scan is very useful because it can collect multiple non-parallel slices at once.
That is, even for many regions of interest that are not necessarily parallel in the human body, such as the spinal disc, images of those many discs can be obtained at one time by one scan,
The imaging time is shortened, which is extremely useful. In this case, the directions, positions, thicknesses, etc. of a large number of slices are set independently of each other. For example, a sagittal image of an MR image obtained in advance is displayed on the screen and Settings for each slice are made by moving the cursor.

[Problems to be Solved by the Invention]

However, as in the past, setting the direction, position, thickness, etc. for each slice independently of each other,
There is a problem that it is inefficient and it takes time to set. In view of the above, the present invention has improved MRI so that a plurality of parallel slices can be collectively set.
The purpose is to provide a device.

[Means for Solving the Problems]

In order to achieve the above object, in an MRI apparatus according to the present invention, a static magnetic field generating means, a means for generating a gradient magnetic field having a predetermined waveform, a means for exciting a subject with an RF signal having a predetermined waveform, and Means for receiving the NMR signal of
A means for forming an image by processing the data obtained from the received NMR signal, an image display means for displaying the image, a position input means for determining the position of the cursor on the screen of the image display means, and a numerical value input Numerical value input means, and after displaying the positioning image on the screen of the image display means, using the position input means and the numerical value input means, the number of the slices for a plurality of slices in the same direction, their positions, between them Set the interval and the thickness of each to 1
It is characterized in that it has a slice setting means for performing one volume unit independently of other volumes, and a control means for controlling the gradient magnetic field waveform and the RF signal waveform based on the set slice.

[Work]

A positioning image such as a sagittal image is displayed on the screen of the image display means, and the slice setting is performed using the position input means for determining the position of the cursor on the screen of the image display means and the numerical value input means for inputting a numerical value. Is done. At this time, a plurality of slices in the same direction are set as one volume. That is, one volume is treated as a set of multiple slices in the same direction, and if the number of slices, their positions, the intervals between them, and their thicknesses are set, the directions are set individually. You don't have to. Further, since the setting for each volume is performed independently of the settings for other volumes, when the slices belonging to one volume are set, the slice settings of other volumes are not affected.

【Example】

An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an MRI apparatus according to an embodiment of the present invention. A subject 1 is placed in a static magnetic field space created by a static magnetic field generating magnet 21. A gradient magnetic field generating coil 22 and a transmission / reception coil 23 are arranged in this space. A current is supplied to the gradient magnetic field generating coil 22 from a gradient magnetic field power source 32, and a gradient magnetic field for slice selection, a gradient magnetic field for reading (frequency coding), and a gradient magnetic field for phase coding are generated. Signals from the waveform generating circuit 31 are sent to the gradient magnetic field power supply 32 to determine the waveforms of these gradient magnetic fields. On the other hand, an RF signal having an envelope corresponding to the waveform transmitted from the waveform generation circuit 33 is transmitted from the RF transmission circuit 34 to the RF signal.
The signal is sent to the transmission / reception coil 23, and the subject 1 is irradiated with the RF signal. The NMR signal generated in the subject 1 is received by the transmission / reception coil 23 and detected by the reception / detection circuit 35.
It is sampled by the A / D converter 36, converted into a digital signal, and taken into the computer 41. The computer 41 controls the gradient magnetic field waveform and the RF signal waveform, controls the gradient magnetic field and the RF signal generation timing, controls the data sampling timing, and processes the captured data to form an image. A CRT display device 42, a keyboard device 43, and a mouse 44 (or another position input device such as a trackball) are connected to the computer 41. The image obtained above is displayed by the CRT display device 42. Here, when performing slice setting of the multi-angle scan, first, an MR image such as a sagittal image obtained in advance is displayed as a positioning image on the CRT display device 42, and then the slice setting program is activated in the computer 41. For example, when performing a multi-angle scan on a large number of spinal discs, a sagittal image of the spine is obtained by a normal scan performed in advance, and this is displayed on the screen of the CRT display device 42 as shown in FIG. Second
In the figure, an image of the spine 51 and an image of the intervertebral disc 52 are shown. The cursor appears on this screen when the slice setting program is started. Therefore, here, by operating the mouse 44, the cursor is moved to determine its direction and position, and the slice is set. When setting a slice for a certain disc 52 with the cursor 61, the direction of the cursor 61 is first made parallel to the disc 52. When the slice direction is determined in this way, the number of slices, the interval between them, the thickness of each, and the like are input from the keyboard device 43. Here, assuming that one slice 71 is set, the number of slices is 1,
Enter the thickness, for example, 20 mm. Then, the cursor 61 is displayed so as to have a width corresponding to the input thickness. Next, the slice for the adjacent disc 52 is set by the cursor 62. Also in this case, first, the direction of the cursor 62 is determined, the number of slices is input as 2, and the interval between these slices and the thickness of each are input in mm. As a result, the cursor 62 comes to represent two slices 72 and 73, and these slices 72 and 73 can be set. In this way, by operating the keyboard device 43 and the mouse 44, the slice direction
The position is accurately determined, and the number of slices is increased or decreased or the slice interval is changed according to the need at that time. In this way, a plurality of slices parallel to each other are sequentially set. This set of a plurality of slices parallel to each other is treated as one volume by the computer 41, and when a certain one volume is set. , Other voivomes are unaffected. That is, different volumes for non-parallel slices are independent, and the number of slices, intervals, thickness, etc. can be set individually for each, and when setting for a certain volume, the slices included in that volume are Does not affect the non-parallel slice (and its volume), and the direction and position of the cursor representing the non-parallel slice does not change. Therefore, if you set the direction once for multiple slices that may be parallel, you do not need to set the direction for each of the multiple slices, you can simply enter the number of slices, the interval, and the thickness, which is very easy. Not only can it be set, but the time required for setting can also be shortened. Therefore, the effect is particularly great in the slice setting of the multi-angle scan for the spinal disc as described above. That is, the spinal discs have slightly different sizes in the neck, chest, lumbar region, etc., and it is necessary to set a thin slice thickness accordingly for small discs and a thick slice thickness for large discs. This is because it is possible to easily perform these, and when it is not desired to change the slice thickness, it is easy to assign a plurality of parallel slices to a large intervertebral disc. When setting for many slices is completed in this way,
The computer 41 calculates the gradient magnetic field waveform and the RF signal waveform corresponding to the setting, and the waveform generating circuits 31 and 3
Set to 3. After that, when a multi-angle scan is executed, data collection is performed on the set large number of slices 71 to 77, and images of the set large number of slices 71 to 77 are obtained at the same time.

【The invention's effect】

According to the MRI apparatus of the present invention, it is possible to collectively set a plurality of slices in the same direction,
This is much easier than setting each slice individually, and the setting time can be shortened.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a diagram showing a screen of a CRT display device when a slice is set. 1 ... Subject, 21 ... Magnet for generating static magnetic field, 22
...... Coil for generating gradient magnetic field, 23 ...... Transceive coil, 3
1 ... Gradient magnetic field waveform generation circuit, 32 ... Gradient magnetic field power supply, 33 ... RF signal waveform generation circuit, 34 ... RF transmission circuit, 35 ... Reception / detection circuit, 36 ... A / D converter, 41 ... Computer, 42 ... CRT display device, 43 ... Keyboard device, 44 ... Mouse, 51 ...
... spine image, 52 ... intervertebral disc image, 61-64 ... cursor, 71-77 ... setting slice.

Claims (1)

[Claims] 1. A static magnetic field generating means, a means for generating a gradient magnetic field having a predetermined waveform, a means for exciting a subject with an RF signal having a predetermined waveform, and a means for receiving an NMR signal from the subject.
A means for forming an image by processing the data obtained from the received NMR signal, an image display means for displaying the image, a position input means for determining the position of the cursor on the screen of the image display means, and a numerical value input Numerical value input means, and after displaying the positioning image on the screen of the image display means, using the position input means and the numerical value input means, the number of the slices for a plurality of slices in the same direction, their positions, between them Set the interval and the thickness of each to 1
An MRI apparatus comprising: slice setting means for performing one volume unit independently of other volumes; and control means for controlling the gradient magnetic field waveform and the RF signal waveform based on the set slice.