JP3241743B2 - Magnetic resonance imaging equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic resonance imaging apparatus, and more particularly, to a magnetic resonance imaging method which separates portions of a human body, such as arteries and veins, having different flow directions from each other and accurately images and displays the same. The present invention relates to a magnetic resonance imaging apparatus capable of performing a display method.

[0002]

2. Description of the Related Art Conventionally, a magnetic resonance imaging apparatus (hereinafter, referred to as an MRI apparatus) is a medical diagnostic apparatus for a human body as an apparatus for creating a large number of slice images for each part of the human body and displaying an image of a target part. It is widely used for such purposes. An outline of an imaging method performed by the MRI apparatus will be described. First, a static magnetic field is applied to a subject to be inspected, and a high-frequency magnetic field having a frequency that induces a magnetic resonance phenomenon is applied. The spin (nuclear magnetism) in the subject is excited by the high frequency magnetic field. Subsequently, a gradient magnetic field for selecting a slice plane position in the Z-axis direction of the subject, a gradient magnetic field for phase encoding in the Y-axis direction of the subject, and a frequency encode having a predetermined magnitude in the X-axis direction. And a gradient magnetic field for reading (or reading) are applied to the subject at a predetermined timing in combination with each other. With these gradient magnetic fields, a part of the subject where a magnetic resonance signal accompanying the above-described magnetic resonance phenomenon is emitted is specified. A magnetic resonance signal is detected from the excited spin at the specified site. Furthermore, by collecting the magnetic resonance signals while changing the position of the specific site, and then executing an operation for image reconstruction, an image of a desired site in the subject can be created and displayed. .

[0003] In addition to the stationary part, the MRI apparatus can also image a periodically operating part such as the heart or a fluid part such as blood flowing through a blood vessel. For the imaging of the fluid part, for example, IEE Transaction on Medical Imaging MI
5, No. 3, pages 140 to 151, 1988 (IEEE,
Trans.on Medical Imaging, MI-5, No.3, pp.140-151,19
88), which is discussed in detail. The drawing principle of the fluid part described in this document will be outlined. A pulse called a “flow encode pulse” is used for imaging the fluid part. The flow encode pulse is
This is a pulse in the imaging signal that causes a phase change according to the flow velocity due to the flow of the fluid. That is, when the flow encode pulse exists in the direction of the flow of the fluid, a phase change corresponding to the flow velocity of the fluid occurs in the imaging signal. Therefore, by performing image-to-image subtraction between an image created using the phase-sensitive sequence including the flow encode pulse and an image created using the phase-insensitive sequence not including the flow encode pulse, an image of the fluid is obtained. Can be performed. This will be described in more detail by taking an example of blood in a blood vessel. The blood flow in the blood vessel is laminar, and the flow velocity of the blood flow is such that the central part is faster and the peripheral part is slower in the radial direction of the blood vessel. , A different phase change occurs in the imaging signal of each part. Therefore, when the imaging data is integrated in the radial direction and the projection is performed, the imaging data cancel each other out, and it is not possible to extract a signal for the blood flow part. On the other hand, when imaging is performed in the phase insensitive sequence, a phase change depending on the blood flow velocity does not occur, so that a signal can be extracted from the blood flow portion even in the case of laminar flow. In addition, for the stationary part of the surrounding tissue, a signal is output in both the phase-sensitive sequence and the phase-insensitive sequence, so that 2
When the subtraction process is performed between the image data obtained in the two sequences, the image of the stationary portion is canceled and disappears, and the image of the blood flow portion can be extracted as the difference between the imaging data obtained in the two sequences. Such a technique of photographing a fluid part of a human body is called a subtraction method.

[0004]

[Problems to be Solved by the Invention] Some human tissues include
As blood in blood vessels, arterial flow and venous flow exist because of their roles. The arteries and the veins are in a substantially parallel positional relationship except for a terminal portion which is a connecting portion thereof, and their flow directions are opposite. Therefore, for example, when applying the above-described subtraction method to a slice surface of a neck portion of a human body to create a fluid portion, that is, an MRI image of a blood vessel portion, the fluid portion displayed in the image is an artery. If it can be identified whether it is a vein or a vein, it can be used as extremely important information in medical diagnosis. However, in the above-described conventional MRI method for imaging a fluid portion, information on the flow direction of the fluid portion with respect to the slice plane to be imaged is completely ignored, and therefore, the drawn fluid portion is an artery. It cannot be identified whether it is a vein or a vein. Thus, according to the subtraction method, there is a problem that arteries and veins cannot be drawn separately on an image.

[0005] A first object of the present invention is to perform MRI for imaging a fluid portion, and a fluid, such as an arterial flow and a venous flow, flowing from different directions with respect to a slice plane intended to be imaged. Is intended to be imaged separately
An object of the present invention is to provide an RI apparatus. A second object of the present invention is to separate an artery image and a vein image which are separately imaged,
M intended to be displayed simultaneously on one two-dimensional screen
An object of the present invention is to provide an RI apparatus.

[0006]

A magnetic resonance imaging apparatus according to the present invention comprises a static magnetic field generating means, a high frequency magnetic field generating means, a gradient magnetic field generating means for selecting a slice plane, and a gradient magnetic field generating means for phase encoding. And a gradient magnetic field generating means for frequency encoding, a receiving means for measuring an echo signal, a control means for repeating a procedure from excitation to measurement of the echo signal while changing the phase encoding, and an image using the echo signal. And a magnetic field, a high-frequency magnetic field, and a gradient magnetic field for selecting a slice plane selectively excite spins of a specific portion of the subject, and apply phase encoding to the spins of the specific portion by phase encoding. Given, read out the echo signal generated from a specific portion, in a magnetic resonance imaging apparatus that reproduces an image using a plurality of obtained echo signals, Before generating the high-frequency magnetic field for the next measurement, the high-frequency magnetic field generating means determines whether the other slice located next to the slice plane depends on the flow direction of the fluid part flowing into the slice plane intended for imaging. After generating a high-frequency magnetic field for presaturating the surface, and generating a gradient magnetic field for slice plane selection, generating a gradient magnetic field for specifying the other slice surface, and generating a high-frequency magnetic field for the original measurement , slice plane selection gradient magnetic field generating means
Is a selection pulse for selecting a slice plane and this
The negative pulse following the selection pulse and the negative pulse
A phase compensation pulse consisting of a positive pulse
The number encoding gradient magnetic field generating means is a frequency encoding
Gradient magnetic field pulse and the negative
Pulse and the positive pulse preceding this negative pulse
The present invention is characterized in that it is configured to generate such a phase compensation pulse. In the above configuration, based on the image data obtained by the receiving unit, the image processing unit is configured to form a three-dimensional image and display it as an image projected on a two-dimensional plane. In the above configuration, one of two slice planes located next to the slice plane intended for imaging is presaturated by a specific thickness before excitation for the original measurement, and one slice plane is pre-saturated. The signal of one of the two fluid portions flowing into the fluid portion is turned off, and the signal of the other fluid portion is selectively extracted with high luminance. In the above configuration, when a slice plane intended for imaging is continuously photographed, other slice planes to be pre-saturated are simultaneously moved at a predetermined interval with the movement of the slice plane intended for imaging. It is characterized by the following. In the above configuration, the two fluid units are, for example, an artery and a vein in a human body, and the artery or the vein is selectively drawn. In the above configuration, a three-dimensional stereoscopic image of an artery or a vein is formed from the obtained two-dimensional or three-dimensional image of the artery or a vein, and is projected on a two-dimensional plane. In the above configuration, when projection is performed on a two-dimensional plane, a pixel having the highest intensity among a set of pixels to be projected is set as a projection destination pixel. In the above configuration, one of two slice planes located next to the slice plane intended for imaging is presaturated by a specific thickness before excitation for the original measurement, and one slice plane is pre-saturated. The signal of one of the two fluid parts flowing into the filter is completely lost, and the signal is selectively blackened and taken out. In the above configuration, 2
When the projection is performed on the dimensional plane, a pixel having the highest weakness among a set of pixels to be projected is set as a pixel to be projected. The above configuration is characterized in that the obtained artery and vein images are combined and displayed with different colors, respectively. The above configuration is characterized in that the anterior-posterior relationship between the artery and the vein is recognized in advance, and the color of the overlapping portion between the artery and the vein is displayed as the front color.

[0007]

In the MRI apparatus according to the present invention, before exciting a slice plane intended to be imaged, a slice plane adjacent to the slice plane, for example, an upper slice plane or a lower slice plane is adjusted to a specific thickness. Only, the excitation is performed by presaturation, and then the excitation for measuring the main body is performed on the slice plane. Thereby, the fluid part in one of the two directions of the fluid part flowing into the slice plane intended for imaging is assumed to be once excited at the original measurement, Since it flows in, it is saturated and does not generate an echo signal. Therefore, in such a pulse sequence, MR
If the I device is operated for photographing, one of the fluid portions flowing into the slice plane intended for imaging from two directions can be selectively depicted with high luminance. In this way, in tomographic imaging of a human body, it becomes possible to separate an arterial image and a vein image and draw them clearly. Furthermore, the arterial image and the vein image selectively drawn can be given different colors, and can be combined and created as a single image in consideration of the context.
Thus, arteries and veins can be distinguished and displayed in one image.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a configuration diagram showing an outline of an MRI apparatus,
FIG. 2 is a waveform diagram of a flow encode pulse that causes a phase rotation in proportion to the flow velocity in the fluid portion, FIG. 3 is a waveform diagram of a phase compensation pulse that compensates the phase rotation of the fluid portion and makes the phase rotation zero, and FIG. FIG. 5 is a chart of a pulse sequence showing one embodiment of the MRI method performed by the MRI apparatus according to the present invention. FIGS. 5 and 6 are diagrams for explaining separation of a fluid part due to a difference in flow direction, and FIG. FIG. 8 is a diagram of three-dimensional display showing one embodiment of the present invention, and FIG. 8 is a diagram showing arterial flow and venous flow separated and displayed.

In FIG. 1, reference numeral 1 denotes a cylindrical magnet device, and the magnet device 1 includes a magnet for generating a uniform static magnetic field and a coil for generating a gradient magnetic field described later. The magnet device 1 has an internal space in which the subject is arranged, and the static magnetic field and the gradient magnetic field are formed in this internal space. 2
Is a probe disposed in the internal space of the magnet device 1, through which transmission and reception of a high-frequency magnetic field are performed. The probe 2 is provided in the vicinity of a subject site to be measured. Reference numeral 3 denotes a gradient magnetic field generation system that generates a magnetic field that changes independently and with a gradient characteristic in each of the set X, Y, and Z axis directions in the subject. The system 3 supplies an exciting current to the coil of the magnet device 1. Gradient magnetic field generation system 3
Includes a gradient magnetic field generating means for slice plane selection (Z-axis direction), a gradient magnetic field generating means for phase encoding (X-axis direction), and a gradient magnetic field generating means for frequency encoding (Y-axis direction). . By the gradient magnetic field generation system 3,
In the subject, a slice plane for extracting a magnetic resonance signal (also referred to as an imaging signal or an echo) can be specified. Reference numeral 4 denotes an excitation system for generating a high-frequency magnetic field for generating magnetic resonance in the subject, and 5 receives and detects a magnetic resonance signal generated from the subject, and then performs A / D conversion.
This is a measurement receiving system to be converted. 6 is a sequence control system for controlling the operation timing of each of the above-described systems 2, 3, and 4, and performing sequence control for extracting a magnetic resonance signal necessary for imaging from a desired site in the subject. This is an image processing system that performs various calculations required for image reproduction based on measurement data output from a system section that performs measurement on a subject. Finally, reference numeral 8 denotes a console, and the operator operates the console 8, gives necessary data and commands, and executes image creation and display.

[0010] MR used in the MRI apparatus according to the present invention
FIG. 2 shows a flow encode pulse used in the sequence of the I method. The flow encode pulse 9 has a positive portion in the first half and a negative portion in the second half with respect to the gradient magnetic field strength. The first half and the second half are equal in area. When the flow encode pulse 9 having such a waveform is applied to the measurement target portion, a phase rotation in proportion to the flow velocity occurs in the fluid portion. The phase rotation generated when the flow encode pulse 9 is applied is shown by a mathematical expression. The phase changes according to the following equation.

[0011]

(Equation 1)

Here, γ is the nuclear magnetic rotation ratio, G (t) is the gradient magnetic field, and S (t) is the position of the object to be measured. S (t) is given as X ₀ + vt using the flow velocity v. Substituting this equation into the above equation, rearranging and simplifying it, gives the following equation.

[0013]

## EQU2 ## φ (t) = − γG ₁ vτ ²

Thus, it can be seen that a phase rotation proportional to the flow velocity occurs in the fluid portion.

When the phase compensation pulse 10 having the waveform shown in FIG. 3 is applied to the fluid part, the phase generated in the flow encode pulse part in the first half is changed by the waveform part in the second half having the opposite shape. , And the phase Φ (t) becomes zero. Here, the “phase compensation pulse” means a pulse that returns a state where the phase has been turned by the flow encode pulse to the original state. Therefore, when the phase compensation pulse shown in FIG. 3 is applied to the fluid part, the phase around the fluid part becomes
Eventually, it will be canceled.

Next, referring to FIG. 4, there is shown a pulse sequence for blowing the flow encode pulse 9 and the phase compensation pulse 10 described above, wherein two fluid parts having different flow directions, for example, arterial flow and venous flow are separated. A pulse sequence that can be described as follows will be described. In FIG. 4, from the top, a high-frequency pulse (RF) and an echo (Echo), a slice plane selection gradient magnetic field, a phase encoding gradient magnetic field,
The gradient magnetic fields for frequency encoding are respectively shown. First, in the high frequency pulse and echo, 11
Is a high-frequency pulse for pre-saturation for exciting a slice surface having a required thickness on the upper surface side or the lower surface side (front side or rear side side) located next to the slice plane intended for imaging in advance. is there. In this presaturation, the spin is rotated by 90 °. Numeral 12 is an original high-frequency pulse for exciting a slice plane intended for imaging. Here, the high frequency pulse refers to the pulsed high frequency magnetic field. High frequency pulse 11,1
The interval TP of 2 is changed in accordance with the fluid part to be imaged, that is, the blood flow velocity. Further, the intensity and the number of times of application of other high-frequency pulses are determined to be optimal in consideration of the blood flow rate and the repetition time TR. Reference numeral 13 denotes an echo obtained from a measurement target site of the subject. Next, in the gradient magnetic field for slice plane selection, 14
Is a gradient magnetic field for selecting a slice plane for performing the presaturation, and 15 is a spoiler pulse for dephasing (disturbing the phase) a magnetic resonance signal generated by the presaturation. The spoiler pulse 15 has a function of eliminating a magnetic resonance signal generated in a stationary part excited by the high-frequency pulse 11. The spoiler pulse 15 simultaneously generates the gradient magnetic fields of the phase encoding and the frequency encoding at the same time.
Generated. The pulse 16 is a pulse for selecting an original slice plane intended for imaging. The pulse 16 and the subsequent pulses 17 and 18 form a phase compensation pulse as is apparent from FIG. Further, the pulse 19 is a gradient magnetic field for phase encoding, and a number of pulses are applied while changing the level sequentially. The pulse 20 is a gradient magnetic field for frequency encoding. The pulse 20 is the pulse 2 that precedes it.
A phase compensation pulse is formed by the steps 1 and 22. Thus, in the MRI method according to the present embodiment, as an example, the phase compensation pulse is included in the gradient magnetic field for slice plane selection and frequency encoding. Further, the pulse 23 generated in each gradient magnetic field is echo 1
3 is a spoiler pulse for the dephase given after measuring the signal of No. 3 and has the same function as the spoiler pulse 15. According to the pulse sequence of the present embodiment, at least in the axis for slice selection and the axis for frequency encoding, a phase compensation pulse for zeroing the phase rotation is given, so that the fluid portion has high brightness. You can draw.

Next, based on FIGS. 5 and 6, the MRI method of separating and photographing and imaging the fluid portions having different flow directions by utilizing the difference in the flow direction of the fluid portions will be described in principle. explain. 5 and 6, it is assumed that 31 is an arterial flow flowing from bottom to top, and 32 is a venous flow flowing from top to bottom. FIG. 5 is a diagram showing a state for photographing the venous flow 32, and FIG. 6 is a diagram showing a state for photographing the arterial flow 31.
It changes in the order of (b). (C) of FIGS. 5 and 6
Shows images of the slice plane obtained by each imaging. In FIG. 5, 33 indicates a slice plane intended for imaging, and 34 indicates a slice plane for performing presaturation. The slice plane 33 is excited by the high-frequency pulse 12, and the slice plane 34 is excited by the high-frequency pulse 11. As described above, in order to image the venous flow 32 flowing from top to bottom, a slice plane 34 for presaturation is set below the slice plane 33. The interval between the two slice planes 33 and 34 and the thickness of the slice plane 34 are appropriately adjusted according to the flow velocity of the vein 32. As an example, the thickness of the slice surface 33 is 3 m
m, the thickness of the slice surface 34 is 4 cm, and the interval between the two slice surfaces 33 and 34 is, for example, 7.5 mm. First, as shown in FIG. 5A, the slice surface 34 is pre-saturated. In this presaturation, the slice surface 34 is selected by the pulse 14 and excitation is performed by the high frequency pulse 11. Next, the slice plane 33 is excited by the high-frequency pulse 12 for signal measurement. At the time of the original imaging, as shown in FIG.
In 1, since the presaturated portion 31 a flows into the slice surface 33, the portion 31 a in the slice surface 33 becomes saturated with the high-frequency pulse 12, and it becomes impossible to take out a photographing signal. In addition, when signal measurement is performed in a short repetition time in the excitation of the slice plane 33, the stationary portion is always in an excited state, so that an excessively large imaging signal is not generated. On the other hand, for the venous flow 32, a very large imaging signal is generated because a new fluid portion always flows into the slice surface 33. As described above, in the slice plane 33 to be imaged, taking into account the flow directions of the arterial flow 31 and the venous flow 32 flowing into the slice plane 33, for example, the slice plane 34 is measured from the slice plane 33 after presaturation. When the signal is captured, venous flow 3
2 can be drawn in a state of high brightness. FIG. 5 (c)
Indicates a slice plane 33 imaged. In this figure, it is possible to differentiate and image the portion of the venous flow 32 with the highest brightness, the stationary portion 35, and the portion of the arterial flow 31 with the lowest brightness. The slice plane 33 intended for imaging is sequentially and continuously moved, and accordingly, the slice plane presaturated is also moved at a predetermined interval. Thus, the MRI according to the pulse sequence of FIG.
In the method, the arterial flow 31 and the venous flow 32 can be separately imaged. Similarly to the above method, FIG.
According to the procedures of (b) and (b), the arterial flow 31 can be separated from the venous flow 32 and selectively imaged, as shown by the high-brightness portion in FIG. In this case, the arterial flow 31 intended for imaging flows from bottom to top,
A slice plane 36 for presaturation is set above the slice plane 33 to be imaged. Thus, an image of the arterial flow 31 can be created on the same principle as in the case of FIG.

In the above embodiment, the imaging of the arterial flow 31 and the venous flow 32 was performed by separate imaging in which each of the images was drawn with high brightness by a separate imaging pulse sequence. Further, as another embodiment, in a method of separating and photographing two fluid parts by using a difference in the flow direction of the fluid part, the fluid part which is saturated in advance before signal measurement has a signal in the photographing signal. Since it is missing in black, using this, either the upper surface side or the lower surface side of the imaging slice surface is simply saturated in advance before signal measurement, and according to the flow direction of each of the two fluid portions, One fluid portion can be drawn as a bright image with high brightness, and the other fluid portion can be drawn simultaneously as a black image in one shooting sequence.

The three-dimensional display will be described with reference to FIG. The arterial flow 3 is obtained by stacking tomographic images of a plurality of slice planes measured by the measuring methods of FIGS. 5 and 6.
The running state of each fluid part of the 1 and the venous flow 32 can be grasped three-dimensionally. FIG. 7A shows a three-dimensional display of the venous flow 32, and FIG. 7B shows a three-dimensional display of the arterial flow 31. In this stereoscopic display, a stereoscopic image is projected and displayed on a two-dimensional plane based on the obtained two-dimensional image or three-dimensional image. In this case, each pixel on the two-dimensional plane on which projection is performed It is preferable to use a pixel having the largest intensity among a plurality of pixels forming a three-dimensional image among pixels corresponding to the two-dimensional plane pixel. In this way, a clear image can be created. Thus, according to the MRI method according to FIGS. 5 and 6,
Fluid portions having different flow directions can be displayed as separate stereoscopic images. Note that, in the above display method, for each pixel on the two-dimensional plane, a pixel having the smallest intensity (a pixel having the largest weakness) among a plurality of corresponding pixels in the stereoscopic image is used, and The flow can be drawn in black. Further, if the display is performed by inverting white and black, the flow in the reverse direction drawn in black can be drawn with high luminance.

As shown in FIG. 8, for the two fluid parts, that is, the arterial flow 31 and the venous flow 32, the images of the three-dimensional display shown in FIG. 7 are synthesized, and different colors are colored and displayed. be able to. In this case, in particular, the positional relationship between the arterial flow 31 and the venous flow 32 is checked in advance, and the overlapping portion uses the color of the portion located on the front side during display.

In the case of the other embodiment, since two fluid portions having different flow directions can be photographed at the same time, the two fluid portions are simultaneously displayed as a three-dimensional image using an image showing the two fluid portions. can do.

In the above-mentioned MRI apparatus, it is possible to project the formed three-dimensional stereoscopic image on a two-dimensional plane by changing the angle. In this case, by continuously changing the angle, the image is continuously projected on a two-dimensional plane,
Cine display is also possible. In addition, two-stage shooting is performed, and in the first shooting, the fluid part to be drawn
It is also possible to form a slice plane along the image, and then designate a slice plane perpendicular to the fluid part as a slice plane to be measured.

[0023]

As apparent from the above description, the present invention has the following effects. In imaging by the MRI method of the MRI apparatus, before the original signal measurement, a slice plane positioned next to the slice plane to be measured and determined depending on the flow direction of the fluid unit intended to be imaged has a desired thickness. Presaturation is performed to eliminate echo signals relating to fluid portions other than the fluid portion intended to be imaged, whereby only the echo signal of one fluid portion can be selectively extracted. This makes it possible to create an image in accordance with the flow direction in creating an image of the fluid part. For example, in a human body, arteries and veins can be separated and displayed. Furthermore, according to the above method, the drawn artery and vein can be colored with different colors, respectively, and synthesized as a single image, and the arrangement state of the context can be clearly distinguished and understood. It is convenient for medical diagnosis.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an outline of an MRI apparatus.

FIG. 2 is a waveform diagram of a flow encode pulse causing a phase rotation in proportion to the flow velocity in a fluid part.

FIG. 3 is a waveform diagram of a phase compensation pulse that compensates for the phase rotation of the fluid part and makes the phase rotation zero.

FIG. 4 is a pulse sequence diagram showing one embodiment of the MRI method according to the present invention.

FIG. 5 is a diagram for explaining separation of a fluid portion due to a difference in flow direction.

FIG. 6 is a diagram for explaining separation of a fluid part due to a difference in flow direction.

FIG. 7 is a diagram of a stereoscopic display showing one embodiment of the present invention.

FIG. 8 is a diagram showing arterial flow and venous flow separated and displayed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnet apparatus 2 Probe 3 Gradient magnetic field generation system 4 Excitation system 5 Receiving system 6 Sequence control system 7 Image processing system 9 Flow encode pulse 10 Phase compensation pulse 11 High frequency pulse for presaturation 12 High frequency pulse for original measurement 13 Echo signal 31 Arterial flow 32 Venous flow 33 Slice plane for original measurement 34 Slice plane for presaturation

Continuation of front page (72) Inventor Koichi Sano 1099 Daiozenji Temple, Aso-ku, Kawasaki City, Kanagawa Prefecture Hitachi, Ltd. System Development Laboratory (56) References JP-A-61-128948 (JP, A) JP-A-1- 236045 (JP, A) JP-A-1-2388851 (JP, A) JP-A-2-63437 (JP, A) JP-A-2-95349 (JP, A) JP-A-2-268743 (JP, A) JP-A-3-82446 (JP, A) JP-A-4-176442 (JP, A) L. DUMOULIN, et al, Magnetic Resonance in Medicine, 9 (1), 139-149 DWIG G. NISHIMUR A, et al, Magnetic Resonance in Medicine, 8 (1), 96-103 Robert R. Edelman, et al, Radiology, 177 (1), 45-50 (58) Fields investigated (Int. Cl. ⁷ , DB name) A61B 5/055

Claims (18)

(57) [Claims] 1. A static magnetic field generating means, a high frequency magnetic field generating means, a gradient magnetic field generating means for slice plane selection, a gradient magnetic field generating means for phase encoding, a gradient magnetic field generating means for frequency encoding, and an echo signal Receiving means for receiving and measuring the signal, control means for repeatedly performing a procedure from excitation to measurement of the echo signal while changing the phase encoding, and image processing means for reproducing an image using the echo signal. The magnetic field, the high-frequency magnetic field, and the slice plane selection gradient magnetic field selectively excite spins in a specific portion of the subject, apply a phase change to the spins in the specific portion by the phase encoding, and generate the spin from the specific portion. In a magnetic resonance imaging apparatus that reads an echo signal and reproduces an image using the plurality of obtained echo signals, a high-frequency magnetic field for original measurement is provided. Before generating the field, the high-frequency magnetic field generating means pre-saturates another slice plane located next to the slice plane, which is determined depending on the flow direction of the fluid part flowing into the slice plane intended for imaging. It said gradient magnetic field generating means of the high frequency magnetic field occurs, and a slice plane for selecting which generates a gradient magnetic field for specifying the other slice plane, after generating a high-frequency magnetic field for the actual measurement, pre Symbol slice Gradient magnetic field generation means for surface selection
Is a selection pulse for selecting a slice plane and this
The negative pulse following the selection pulse and the negative pulse
Generating a phase compensation pulse consisting of a positive pulse and
The frequency encoding gradient magnetic field generating means includes a frequency encoder.
And a gradient magnetic field pulse for
Negative pulse and the positive pulse preceding this negative pulse
Magnetic resonance imaging apparatus characterized by being configured to generate a phase compensation pulse composed of a. 2. The magnetic resonance imaging apparatus according to claim 1, wherein said receiving means measures an echo signal.
A magnetic resonance imaging apparatus, wherein each of the gradient magnetic field generating means generates a spoiler gradient magnetic field that forcibly disturbs a phase of an echo signal generated thereafter. 3. The magnetic resonance imaging apparatus according to claim 1, wherein said image processing means forms a three-dimensional stereoscopic image based on the image data obtained by said receiving means.
A magnetic resonance imaging apparatus for displaying an image projected on a two-dimensional plane. 4. A magnetic resonance imaging apparatus according to claim 1, wherein said image processing means forms a three-dimensional stereoscopic image in which a fluid portion is emphasized based on the image data obtained by said receiving means. A magnetic resonance imaging apparatus for displaying an image projected on a magnetic resonance image. 5. The magnetic resonance imaging apparatus according to claim 3 , wherein the configured three-dimensional stereoscopic image is
A magnetic resonance imaging apparatus characterized in that it is projected on a two-dimensional plane by changing an angle. 6. The magnetic resonance imaging apparatus according to claim 5 , wherein the constituted three-dimensional stereoscopic image is continuously projected on a two-dimensional plane by changing an angle, and is displayed in a cine form. Magnetic resonance imaging device. 7. The magnetic resonance imaging apparatus according to claim 1, wherein one of two slice planes located next to the slice plane intended to be imaged is specified before excitation for the original measurement. It is characterized in that presaturation is performed by an amount corresponding to the thickness, one signal of the two fluid parts flowing into the one slice surface is turned off, and the signal of the other fluid part is selectively extracted with high luminance. Magnetic resonance imaging equipment. 8. The magnetic resonance imaging apparatus according to claim 1, wherein two-stage imaging is performed, and in the first imaging, a slice plane along the travel of the fluid portion is imaged,
Next, a slice plane perpendicular to the fluid part is designated as a slice plane to be measured. 9. The magnetic resonance imaging apparatus according to claim 1, wherein the thickness of the other slice surface to be pre-saturated and the distance between the other slice surface and the slice surface intended for imaging are determined by the fluid. A magnetic resonance imaging apparatus characterized in that the magnetic resonance imaging apparatus is determined in accordance with the flow rate of the section. 10. The magnetic resonance imaging apparatus according to claim 1, wherein, when continuously taking a slice plane intended for imaging, said other slice plane to be presaturated is also a slice plane intended for imaging. A magnetic resonance imaging apparatus, wherein the apparatus is simultaneously moved at a predetermined interval while moving. 11. The magnetic resonance imaging apparatus according to claim 7 , wherein the two fluid parts are an artery and a vein, and the artery or the vein is selectively drawn. 12. A magnetic resonance imaging apparatus according to claim 11, wherein a three-dimensional image of the artery or vein is constructed from the obtained two-dimensional or three-dimensional image of the artery or vein and projected on a two-dimensional plane. A magnetic resonance imaging apparatus, characterized in that: 13. A magnetic resonance imaging apparatus according to claim 12 , wherein, when projecting onto said two-dimensional plane, a pixel having the highest intensity among a set of pixels to be projected is a pixel to be projected. A magnetic resonance imaging apparatus comprising: 14. A magnetic resonance imaging apparatus according to claim 1, wherein one of two slice planes located next to the slice plane intended for imaging is specified before excitation for the original measurement. Presaturation by the thickness,
A magnetic resonance imaging apparatus characterized in that one of the two fluid portions flowing into one of the slice planes is completely missing and selectively blackened for extraction. 15. In the magnetic resonance imaging apparatus according to claim 14, when projecting onto a two-dimensional plane, the pixel having the largest weakness among a set of pixels to be projected is set as a pixel to be projected. A magnetic resonance imaging apparatus comprising: 16. The magnetic resonance imaging apparatus according to claim 1, wherein one of two slice planes located adjacent to the slice plane intended for imaging is specified before excitation for the original measurement. Presaturation by the thickness,
The signal of one of the two fluid portions flowing into the one slice surface is completely lost, selectively blackened and taken out, and the signal of the other fluid portion is taken out with high brightness. Magnetic resonance imaging device. 17. The magnetic resonance imaging apparatus according to claim 12, wherein the obtained arterial and vein images are combined and displayed with different colors. 18. The magnetic resonance imaging apparatus according to claim 17 , wherein the anteroposterior relationship between the artery and the vein is recognized in advance, and the color of the overlapping portion between the artery and the vein is displayed as the front color. Magnetic resonance imaging equipment.