JPH0620442B2 - 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, conventionally, the direction for each of a number of slices,
The position, thickness, etc. are set, and for example, an MR image obtained in advance is displayed on the screen as a positioning image, and a slice figure or the like is moved on the image to set each slice. .

[Problems to be Solved by the Invention]

However, setting the direction, position, thickness, etc. for each slice as in the conventional case is inefficient, and there is a problem that setting takes time. In view of the above, it is an object of the present invention to provide an improved MRI apparatus that enables easy and accurate slice setting, focusing on the fact that slice setting can be classified for each diagnostic site.

[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 data obtained from the received NMR signal, an image display means for displaying the image, and a storage means for storing an initial value regarding a preset slice predetermined for each diagnostic region. , This initial value is read out and displayed as a slice figure corresponding to a slice on the screen of the image display means and overlapped with the positioning image, and the displayed slice figure is corrected by correcting the initial value, and the position of the slice is corrected. It is characterized by having slice setting means for setting the direction and thickness, and control means for controlling the above gradient magnetic field waveform and RF signal waveform based on the set slice.

[Work]

When displaying a positioning image and setting a large number of slices in order to perform a multi-angle scan of a region, an initial value of a set slice relating to the region is read out from the storage means, and a graphic representing a slice indicated by the initial value information. Is displayed over the positioning image. When a correction for the set slice is instructed, the initial value is corrected, and the slice graphic is corrected so as to represent the corrected slice. So by observing this,
You can check whether the slice has been set optimally. If it is not the optimum one, the correction is instructed again, the corrected slice graphic is displayed, and this is repeated, so that the optimum slice setting can be easily reached. The initial values for the set slices are calculated in advance and stored in the storage means so that some corrections are required when setting a large number of slices for each part. Therefore, a small amount of correction is required, which facilitates complicated setting work for a large number of slices for multi-angle scanning and enables accurate setting.

【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. Further, the computer 41 has a slice setting memory 4
5 is connected. The slice setting memory 45 stores initial value information regarding a set slice for each expected diagnosis site. That is, the part to be imaged by the multi-angle scan is usually the spine, the left and right optic nerves, the knee joint, etc. When the setting of many slices in them is typified, it becomes as shown in FIG. The left and right optic nerves are as shown in FIG. 3, and the knee joints are as shown in FIG. Therefore, information of initial values (such as those in FIGS. 2, 3, and 4) regarding slices set for each of these regions is obtained in advance, and these are stored in the memory 4
It is stored in 5. This initial value is required so that the slice setting of each part can be easily performed with a slight modification later. Here, the slice setting will be described assuming that a multi-angle scan is performed to diagnose the left and right optic nerves. First, as shown in FIG. 5, a transverse image of the head obtained in advance by this MRI apparatus is shown in FIG.
After being displayed on the screen of No. 2, the slice setting program is started in the computer 41. And the memory 45
The information of the set slice initial value (FIG. 3) for the optic nerve is read from and the slice graphic representing the slice indicated by the information is displayed on the screen of the CRT display device 42 as shown in FIG. Next, here, the keyboard device 43 and the mouse 44 are operated to instruct to correct the direction and position of the slice. Then, the information about the modified slice is stored in another section of the memory 45, and at the same time, a slice graphic representing the modified slice appears on the screen of the CRT display device 42. Therefore, by repeating this, optimum and accurate slice setting can be performed. When the setting of a large number of slices for the left and right optic nerves is completed in this way, the gradient magnetic field waveform and the RF signal waveform corresponding to the setting are obtained by the computer 41 and set in the waveform generating circuits 31, 33. After that, when a multi-angle scan is executed, data acquisition for the set large number of slices is performed, and images of the set large number of slices are obtained at the same time. When the spine is imaged by the multi-angle scan, the sagittal image of the spine obtained in advance is displayed on the screen of the CRT display device 42, and the initial value information of the set slice as shown in FIG. Read more,
Display the slice figure corresponding to that slice over the sagittal image of the spine part, add correction in the same way as above,
Set the optimum slice. When performing indirect knee imaging with a multi-angle scan, a transverse image of the indirect knee area obtained in advance is C
After being displayed on the screen of the RT display device 42, the initial value information of the set slice as shown in FIG. 4 is read out from the memory 45, and the slice figure corresponding to the slice is displayed so as to be superimposed on the sagittal image of the spine. , Make corrections in the same manner as above and set the optimum slice. In addition, here, the operator reads the initial value information of the set slice from the memory 45 according to the imaging region,
The corresponding initial value information may be automatically read. It is also possible to store the set slice information as an initial value when there is a need to retain the set slice information in the process of imaging various parts by multi-angle scanning. Is. This allows the operator to collect and save initial values that are actually useful when setting slices.

【The invention's effect】

According to the MRI apparatus of the present invention, complicated setting work for a large number of slices for multi-angle scanning can be facilitated and accurate setting can be performed. as a result,
As a whole, the time for imaging can be shortened, the burden on the patient and the burden on the operator can be reduced, and the patient throughput of the MRI apparatus is improved.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIGS. 2, 3, and 4 are diagrams showing initial values of set slices, and FIG.
The figure shows the screen of the CRT display device when the 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, 45 ...
… Slice setting memory.

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 data obtained from the received NMR signal, an image display means for displaying the image, and a storage means for storing an initial value regarding a preset slice predetermined for each diagnostic region. , This initial value is read out and displayed as a slice figure corresponding to a slice on the screen of the image display means and overlapped with the positioning image, and the displayed slice figure is corrected by correcting the initial value, and the position of the slice is corrected. An MRI apparatus having slice setting means for setting the direction and thickness, and control means for controlling the gradient magnetic field waveform and the RF signal waveform based on the set slice.