JPH07178068A - Magnetic resonance analyzing method and system therefor - Google Patents

Abstract

PURPOSE:To form a clear and a high-speed MR image by applying plural inclined magnetic field pulses together with plural RF pulses simultaneously, when the Tag to be a radial or a grid-form pattern is formed prior to a normal pulse sequence for photographing the image. CONSTITUTION:When an MR image is photographed, at first, a section to be imaged is decided, and then it is decided what positions of the interested section the picture elements of the obtained image correspond to. On the other hand, when an MR image with Tag is produced, the tagging sequence part T, the waiting time part W, and the imaging sequence part I are provided in the pulse sequence in which the RF pulse axis RF, the slice selection axis Gs, the phase encode axis Gp, and the reading axis Gr are shown, and a normal pulse sequence for photographing MR image is used to the sequence part I, while the condition of spin is decorated spatially in the sequence part T. Consequently, an image in which the condition of spin is superposed prior to the imaging can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an MR (magnetic resonance) analysis method and an apparatus therefor. More specifically, the present invention relates to an MR analysis method and an apparatus therefor, which are capable of high-speed and clear imaging and are useful as medical analysis equipment and the like.

[0002]

2. Description of the Related Art The sophistication of medical technology is advancing rapidly, and it has become possible to observe the human body tissue and its function in more detail. However, it is certain that many problems remain to be solved under the present circumstances. For example, analyzing the complex motion of the myocardial wall has great clinical significance. However, echo, which has been conventionally used as a means for observing the movement of the myocardial wall,
cardiography, ultra fast CT, biplane angiocardiogr
Aphy, myocardial scintigraphy, fast scan by MR, etc. can make a qualitative diagnosis of the movement of the myocardial wall, but it is difficult to quantitatively analyze the motility and stress of each local part of the myocardial wall. Met. On the other hand, there is a report in which a metallic marker is embedded in the myocardium for quantitative analysis of myocardial wall motion, but it is invasive and difficult to use in daily clinical practice.

If it becomes possible to non-invasively and non-invasively track a change in position according to the cardiac phase of each part of the myocardial wall,
It is possible to extract data that can be used for the exercise performance evaluation and stress analysis for each local region of the myocardial wall, which is the above-mentioned problem. As such means, Tagging by MR device
Has been reported. Tagging is a new MR imaging pulse sequence. By adding a pulse sequence that creates a radial or lattice pattern (called Tag) in the image before the normal image capturing pulse sequence, tagging is performed. This is a method of obtaining an image. Ze
Rhouni et al. have developed a technique for placing Tags in a radial pattern centered within the heart chamber. On the other hand, Axel et al. Developed a method of inserting Tag in an image in parallel. Both methods enable the movement of the myocardial wall to be known through the distortion of Tag, and the accuracy of analysis of myocardial wall motion is improved compared to the conventional methods. However, although the method of Zerhouni et al. Facilitated the tracking of the rotational motion of the myocardial wall within the imaging cross section, it has the drawback that the complicated'twisting 'motion of the myocardial wall cannot be extracted sufficiently. On the other hand, the method of Axel et al.
Although the shortcomings of the methods such as ni have been overcome and it has become possible to extract the motion of each part of the myocardial wall, the number of tags that can be inserted into the myocardium is small, so it can be used for stress analysis in the myocardial wall. Can be said to be an insufficient method.

Therefore, the present invention solves the drawbacks of the conventional method as described above, and a new method of creating an image with Tag, in which even mechanical stress and strain of the myocardial wall can be obtained for each local region, that is, a new method. It is intended to provide an MR analysis method. Although the finite element method is suitable for mechanical stress / strain analysis, the analysis part is divided into a finite number of elements for the finite element method analysis, and according to the time phase of the node that constitutes each element. It is necessary to know the change in position. Therefore, another object of the present invention is to provide a new method capable of adding as much Tag as possible to the cross section of the myocardial wall in order to improve the accuracy of mechanical analysis.

[0005]

In order to solve the above problems, the present invention provides a plurality of Rs at the time of tag formation.
An MR analysis method characterized by applying a plurality of gradient magnetic field pulses simultaneously with an F pulse. More specifically, one feature is that the gradient magnetic field pulse is applied simultaneously in two directions of the phase encode axis and the read axis.

Furthermore, the present invention proposes to apply a binomial distribution mode pulse in order to enable clearer high speed imaging. The present invention will be described in more detail below. First, the conventionally known creation of MR images with tags will be described, and then the method of the present invention and further examples will be described.

Creation of MR Image with Tag When capturing an MR image, first, a cross section to be imaged is determined, and then, which position of the cross section of interest each pixel corresponds to is determined. For that purpose, it is necessary to treat the MR signal as a function of position, and a method of superimposing an external static magnetic field and a gradient magnetic field in three axial directions orthogonal to each other is used.

In the normal photographing sequence, the following assumptions are implicitly understood. That is, spins placed in a static magnetic field move in phase when excited by an RF pulse, and in a linear gradient magnetic field, the phase difference between spins is a function of position. Therefore, as a result, the phase difference due to the difference in the position of each spin is absorbed by the reconstruction algorithm during MR image reconstruction and
The image reflects the spin state under a static magnetic field.

On the other hand, when an MR image with Tag is created, the situation of spin is different from the above. M with this Tag
FIG. 1 shows a pulse sequence for creating an R image. RF, Gs, Gp, and Gr in the figure are RF, respectively.
The pulse axis, slice selection axis, phase encode axis, and read axis are shown. Also, the pulse sequence is roughly 3
It consists of two parts. Tagging Sequence respectively
A part (T), a waiting time part (W), and an Imaging Sequence part (I).

In the Imaging Sequence part (I), a normal M
A pulse sequence for R image capturing is used. In the case of FIG. 1, a pulse sequence of the spin echo (SE) method is shown. On the other hand, in the Tagging Sequence part (T), the spin state is spatially modified. That is, by modifying the spin state from the state in which the phases are aligned to the state in which the phases are spatially different before the application of the imaging pulse sequence, such spins before imaging in the subsequent imaging sequence. It is possible to obtain an image in which the above states are superimposed. How to spatially modify the spin state before imaging depends on the combination of pulses in the Tagging Sequence portion (T).

The waiting time portion (W) is the time from the formation of Tag to the application of an imaging pulse sequence for actually creating an image with Tag. If there is no waiting time portion (W), the state of the spatially modified spin before imaging is directly reflected in the image in the form of Tag. On the other hand, by providing this waiting time, the movement of spins during the waiting time is reflected in the image as Tag distortion. Therefore, by imaging the heart and other organs accompanied by movement by the MR image capturing method with Tag, the movement of the organs can be grasped as distortion of Tag.

Tagging Sequence and Tag Shape Since the Tag shape is determined by the state of the spin before imaging, the Tagging Sequen that spatially modifies the spin.
It is necessary to understand the relationship between the combination of pulses in the ce portion (T) and the shape of Tag. Further, it is necessary to know what determines the number of tags.

The Tagging Sequence (T) shown in FIG. 1 is represented by two RF pulses and one gradient magnetic field pulse added to the phase encode axis. Consider what kind of Tag shape such a combination of pulses creates. FIG. 2A shows the Imaging Sequence of FIG.
It is a pulse sequence for MR image line formation of the phantom image | photographed by the SE method of the part (I). FIG. 2B is the image. The phantom was filled with 10 mMOL copper sulfate solution.

3 (a) and 3 (b) are a tagging sequence portion (T) of a pulse sequence used for imaging and an image, and 15 tags are formed in the horizontal direction of the image. Axel et al. Insert a grid-like Tag in an image by applying such a pulse sequence two-dimensionally. 4A and 4B show the T used by Axel and others.
Tagging Sequ of pulse sequence for capturing images with ag
The ence part and the image photographed by this are shown. As is clear from the pulse sequence of the Tagging Sequence section, a combination of two RF pulses and two gradient magnetic field pulses applied in the uniaxial direction is a continuous sequence. The first two RF pulses and the gradient magnetic field pulse applied on the read axis form 15 tags in the vertical direction of the image, and the two subsequent RF pulses and the gradient magnetic field pulse applied on the phase encode axis Similar to FIG. 3, fifteen tags are formed in the horizontal direction of the image, and as a result, orthogonal lattice-shaped tags are formed.

New Tagging Sequence and Ta of this invention
Since the shape Tag of g is formed by a combination of two RF pulses and one gradient magnetic field pulse, the number of Tag is determined by the strength of the applied gradient magnetic field pulse as long as it takes the form of such a pulse sequence. . Therefore, the number of tags that can be added in the image is MR
It will be limited to the hardware performance of the device.

In the present invention, Tag exceeding the above limit
We are proposing a new Tagging Sequence that can be added. 5 (a) and 5 (b) show this new Tagging Se.
quence and the image taken by this are shown. The difference from the conventional Tagging Sequence is that two gradient magnetic field pulses applied simultaneously with two RF pulses are used for Tag formation. The intensity of the gradient magnetic field pulse on each phase encode axis and the read axis is within the hardware limit of the MR device. Taggin in Figure 5 (a)
The shooting conditions of g Sequence are the same as those in FIG. 3 (partly the same as in FIG. 4), but the number of formed Tag is 2
It is one. Unlike the conventional Tag formation using a gradient magnetic field pulse that is applied only in the one-axis direction, although the Tag direction is inclined by 45 degrees, it is possible to increase the number of Tags. This is done by applying a gradient magnetic field pulse simultaneously in two directions, the phase encode axis and the read axis,
This is because the gradient magnetic field strength felt by the spin is a biaxial vector-like synthetic magnetic field strength, and the number is √2 times as large as when a gradient magnetic field pulse is applied in the uniaxial direction in the direction in which Tag is inclined by 45 degrees. Is.

Further, in this image formation, it is possible to form a sharper high-speed image by applying a binomial distribution type pulse. Since it becomes sharper as a pulse, it is extremely effective for image formation. Hereinafter, the method, the apparatus, and the effect of the present invention will be described more specifically with reference to examples.

[0018]

EXAMPLE An MR image of the present invention was acquired by photographing based on the above new Tagging Sequence. The MR device used at that time is SIGNA (1.5T) manufactured by GE, USA. FIG. 6 shows the pulse sequence used for the preparation of the cardiac MR image with Tag. As is apparent from FIG. 6, the basic form of the pulse sequence used is the same as that of FIG. 5, but two consecutive pulse groups for inserting Tag orthogonal in directions different by 90 degrees as in the case of FIG. Is used. The first two RF pulses and the phase-encoding axial and read-out axis gradient magnetic field pulses sandwiched between them form a Tag running from the upper left to the lower right in the image, and the next similar pulse group from the upper right to the lower left. A running Tag is formed. The shape and direction of the Tag can be freely changed by changing the flip angle α of the RF pulse and the amplitude and time width of the gradient magnetic field pulse. After Tagging Sequence, an electrocardiogram-gated SE is used to form an image with a certain waiting time.
Method is used. The shooting condition of the SE method is the repetition time (T
R) = 1 time required for one heartbeat, echo time (TE) = 20
ms. The image is an AXIAL image, the matrix size of which is 256 × 128, the slice thickness is 10 mm, and the number of additions is two. The subject was a healthy volunteer, the average heart rate was 62 beats / minute, and the heart rate during the examination was stable. The pulse application was based on the binomial distribution pattern. The captured MR image with Tag is shown in FIGS. 7 and 8. In each, (a) shows the site | part of each imaging | photography cross section. Both are 10 mm apart. (B)-(h) is 7 from end systole to diastole
The number of sheets is 50, and the time interval of each is 50 ms. The reason for choosing this cardiac phase is that we expected the knowledge that would lead to the mechanical expression of the passive diastolic characteristic of the myocardium and the myocardial stress-strain relationship and hardness-stress relationship. The reason why two different cross sections were selected is to know the difference in myocardial wall motion depending on the site.

The following findings can be obtained from FIGS. 7 (b) to 7 (h). (B) Although the right and left ventricles are contracting,
The Tag interval near the apex of the heart is slightly wider than in other cases, and it is presumed that dilation has already started in both the right and left ventricles. (C) It can be understood that the Tag interval at the apex is further widened, and the ventricle is in a dilated state. The myocardial wall near the tricuspid valve on the right ventricular free wall side seems to be moving along the myocardial wall. It is considered to be related to valve movement associated with blood inflow from the right atrium to the right ventricle. In addition, Tag disappears at the apex end of the ventricular septum, and it is expected that the ventricular septum is performing some movement.

(D) Expansion of the right and left ventricles is promoted by the inflow of blood, and it is considered that there is a rapid movement of the myocardium in the region near the tricuspid valve on the right ventricle free wall side and the apex right ventricle side. . However, there is no significant change in the left ventricular free wall. On the other hand, in the interventricular septum, a'twisting 'motion is observed at the apex end and the ventricular base end, and the septal thickness is becoming thin accordingly.

(E) The ventricle is further expanded. In the right ventricle, the movement of the myocardium toward the opposite direction of the ventricle base side and the apex side from the center of the free wall of the right ventricle is observed, and the velocity is also increased. There is no significant change in the wall thickness of the left ventricle, but on the epicardial side of the left ventricle, there is a rotational movement from the apex to the free wall toward the base of the ventricle. No significant movement was seen on the endocardial side. On the other hand, in the interventricular septum, the'twisting 'motion becomes more prominent, and it can be well understood that the anticlockwise rotation is seen from the apex. In addition, the degree of'twisting 'is larger at the base side of the ventricle than at the apex side.

(F) Unlike the slow ventricular dilation shown in (b) to (e) above, a rapid dilation of the ventricle is observed. As a result, in the central part of the free wall of the left ventricle, the movement of the myocardial wall was too fast, and Tag could not follow the change, and it seems that the MR signal disappeared. In the interventricular septum, the'twisting 'movement is more advanced. (G) The ventricle further expands, and along with it, the motion of the wall from the free wall of the right ventricle to the apex becomes more intense. In the left ventricle, the free wall of the left ventricle greatly expands from the center to the base, and the wall thickness there is thin. From the Tag interval, it can be understood that the force is acting from the endocardial side to the epicardial side in the left ventricular free wall. On the other hand, from the center of the free wall of the left ventricle to the apex of the heart, the Tag interval spreads on the endocardial side and no significant change was observed on the epicardial side. It can be read that it is sequentially performed on the adventitia side. The'twist 'of the interventricular septum is further advanced.

(H) The ventricle is further expanded, and the myocardial wall thickness of both the right ventricle and the left ventricle is thin. In addition, the interventricular septum was further'twisted ', and the septal thickness was about half compared with that at the end systole. As the ventricles expand, you can see how the entire myocardial wall is moving. The following findings can be obtained from FIGS. 8 (b) to 8 (h).

(B) Judging from the interval of the Tag of the apex, it is presumed that the dilation of both the right ventricle and the left ventricle has already started. (C) The interval of Tag at the apex is further widened, and the ventricle is expanding. It is expected that there will be a loss of Tag at the mid-ventricular apex end, and a'twisting 'motion has begun in the ventricular septum.

(D) Expansion of the right and left ventricles is promoted by the inflow of blood, and rapid movement of the myocardium is recognized on the epicardial side.
However, no major changes were seen on the endocardial side. In the interventricular septum, a'twisting 'motion is seen in the counterclockwise direction as seen from the apex. (E) The ventricle is further expanded. In the right ventricle, the movement of the myocardium toward the opposite side of the ventricle base side and the apex side from the center of the free wall of the right ventricle is observed. There is no significant change in left ventricular thickness, but there is a rotational movement from the apex to the free wall toward the base of the ventricle on the epicardial side of the left ventricle. The'twist 'movement is more pronounced in the ventricular septum.

(F) A rapid dilation of the ventricles is seen. As a result, in the central part of the left ventricle free wall, the movement of the myocardial wall is too fast, and Tag cannot follow the change.
The signal is missing. The apex end of the septum of the ventricle largely moves to the left ventricle free wall side. In the interventricular septum, the'twisting 'movement is more advanced. (G) The ventricle is further expanded and the myocardial wall is thinned overall. The left ventricle wall not only extends in the cross section in the figure, but the degree of'twisting 'from the top to the bottom in the cross section is slightly reduced near the base of the free wall ventricle.

(H) The volume of the ventricle is slightly reduced, and the thickness of the left and right ventricle walls is slightly increased accordingly. Also, the'twisting 'movements at the base of the left ventricle and in the septum of the ventricle appear to be gradual. As is clear from the above findings, the patterns of myocardial wall motion in FIGS. 7 and 8 were almost the same. However, in detail, it can be said that there is a difference in myocardial wall motion due to the difference in the position of the fault plane. The differences are recognized in the following points.

The'torsion 'motion in the septal ventricle was greater in FIG. 8 than in FIG. In FIG. 7, the “twist” of the ventricular septum was larger on the ventricular base side than on the apex side, whereas in FIG. 8, it was larger on the apex side. All of these seem to be the result of the movement of the myocardial wall at the apex.

On the other hand, in common, the rotational movement of the myocardial wall within the cross section was larger on the epicardial side than on the endocardial side. As described above, by using the pulse sequence for image capturing with Tag of the present invention in the MR apparatus, it becomes possible to know the motion of the myocardial wall through the distortion of Tag. Further, it becomes easy to trace the change in the position of each part of the myocardial wall according to the cardiac time phase, which is far superior to the conventional method for analyzing the motion of the myocardial wall.

[0030]

As described in detail above, according to the present invention, it becomes possible to insert a plurality of tags in the cross section of the myocardial wall, and thereby the behavior of the myocardium in the cross section is visualized. Furthermore, these data can be used for stress-strain analysis by the finite element method. From the number of tags added to the cross section of the myocardial wall, it becomes easier to estimate the myocardial wall thickness, the wall myocardial weight, and the like. By constructing each cross-sectional image three-dimensionally, it is possible to three-dimensionally display the complicated contraction and expansion dynamics of the heart.

As a specific effect of these, clear and high-speed image forming MR analysis can be performed.

[Brief description of drawings]

FIG. 1 is a pulse sequence diagram for creating an MR image with Tag.

2A and 2B are a normal image forming pulse sequence diagram and a phantom image (indicated by a spin echo method) captured by the pulse sequence diagram.

3 (a) and 3 (b) are pulse sequence diagrams for adding Tag in the horizontal direction, and a phantom image with Tag captured by this (only the sequence of the Tagging sequence part is displayed). It is a figure.

4 (a) and 4 (b) are pulse sequence diagrams for adding a grid-shaped Tag, respectively, and a phantom image with Tag captured by this (only the sequence of the Tagging sequence part is displayed). It is a figure.

5 (a) and 5 (b) are respectively a new Tagging sequence diagram according to the present invention and a phantom image diagram with Tag added obliquely produced by the new Tagging sequence diagram.

FIG. 6 is a new Tagging sequence diagram in the present invention.

FIG. 7 (a) is a cross-sectional position of a photograph and (b) to (h) Tag.
It is a figure in which the images are sequentially photographed from the end systole, and the intervals between the images are 50 ms, respectively, in the eccentric MR cine images.

FIG. 8A is an MR cine image view with Tag similar to FIGS. 7A and 7B, and FIG.

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[Procedure amendment]

[Submission date] March 26, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Detailed explanation of the invention

[Correction method] Change

[Correction content]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an MR (magnetic resonance) analysis method and an apparatus therefor. More specifically, the present invention relates to an MR analysis method and an apparatus therefor, which are capable of high-speed and clear imaging and are useful as medical analysis equipment and the like.

[0002]

2. Description of the Related Art The sophistication of medical technology is advancing rapidly, and it has become possible to observe the human body tissue and its function in more detail. However, it is certain that many problems remain to be solved under the present circumstances. For example, analyzing the complex motion of the myocardial wall has great clinical significance. However, echo, which has been conventionally used as a means for observing the movement of the myocardial wall,
cardiography, ultra fast CT, biplane angiocardiogr
Aphy, myocardial scintigraphy, fast scan by MR, etc. can make a qualitative diagnosis of the movement of the myocardial wall, but it is difficult to quantitatively analyze the motility and stress of each local part of the myocardial wall. Met. On the other hand, there is a report in which a metallic marker is embedded in the myocardium for quantitative analysis of myocardial wall motion, but it is invasive and difficult to use in daily clinical practice.

If it becomes possible to non-invasively and non-invasively track a change in position according to the cardiac phase of each part of the myocardial wall,
It is possible to extract data that can be used for the exercise performance evaluation and stress analysis for each local region of the myocardial wall, which is the above-mentioned problem. As such means, Tagging by MR device
Has been reported. Tagging is a new MR imaging pulse sequence. By adding a pulse sequence that creates a radial or lattice pattern (called Tag) in the image before the normal image capturing pulse sequence, tagging is performed. This is a method of obtaining an image. Ze
Rhouni et al. have developed a technique for placing Tags in a radial pattern centered within the heart chamber. On the other hand, Axel et al. Developed a method of inserting Tag in an image in parallel. Both methods enable the movement of the myocardial wall to be known through the distortion of Tag, and the accuracy of analysis of myocardial wall motion is improved compared to the conventional methods. However, although the method of Zerhouni et al. Facilitated the tracking of the rotational motion of the myocardial wall within the imaging cross section, it has the drawback that the complicated'twisting 'motion of the myocardial wall cannot be extracted sufficiently. On the other hand, the method of Axel et al.
Although the shortcomings of the methods such as ni have been overcome and it has become possible to extract the motion of each part of the myocardial wall, the number of tags that can be inserted into the myocardium is small, so it can be used for stress analysis in the myocardial wall. Can be said to be an insufficient method.

Therefore, the present invention solves the drawbacks of the conventional method as described above, and a new method of creating an image with Tag, in which even mechanical stress and strain of the myocardial wall can be obtained for each local region, that is, a new method. It is intended to provide an MR analysis method. Although the finite element method is suitable for mechanical stress / strain analysis, the analysis part is divided into a finite number of elements for the finite element method analysis, and according to the time phase of the node that constitutes each element. It is necessary to know the change in position. Therefore, another object of the present invention is to provide a new method capable of adding as much Tag as possible to the cross section of the myocardial wall in order to improve the accuracy of mechanical analysis.

[0005]

In order to solve the above problems, the present invention provides a plurality of Rs at the time of tag formation.
An MR analysis method characterized by applying a plurality of gradient magnetic field pulses simultaneously with an F pulse. More specifically, one feature is that the gradient magnetic field pulse is applied simultaneously in two directions of the phase encode axis and the read axis.

Furthermore, the present invention proposes to apply a binomial distribution mode pulse in order to enable clearer high speed imaging. The present invention will be described in more detail below. First, the conventionally known creation of MR images with tags will be described, and then the method of the present invention and further examples will be described.

Creation of MR Image with Tag When capturing an MR image, first, a cross section to be imaged is determined, and then, which position of the cross section of interest each pixel corresponds to is determined. For that purpose, it is necessary to treat the MR signal as a function of position, and a method of superimposing an external static magnetic field and a gradient magnetic field in three axial directions orthogonal to each other is used.

In the normal photographing sequence, the following assumptions are implicitly understood. That is, spins placed in a static magnetic field move in phase when excited by an RF pulse, and in a linear gradient magnetic field, the phase difference between spins is a function of position. Therefore, as a result, the phase difference due to the difference in the position of each spin is absorbed by the reconstruction algorithm during MR image reconstruction and
The image reflects the spin state under a static magnetic field.

On the other hand, when an MR image with Tag is created, the situation of spin is different from the above. M with this Tag
FIG. 1 shows a pulse sequence for creating an R image. RF, Gs, Gp, and Gr in the figure are RF, respectively.
The pulse axis, slice selection axis, phase encode axis, and read axis are shown. Also, the pulse sequence is roughly 3
It consists of two parts. Tagging Sequence respectively
A part (T), a waiting time part (W), and an Imaging Sequence part (I).

In the Imaging Sequence part (I), a normal M
A pulse sequence for R image capturing is used. In the case of FIG. 1, a pulse sequence of the spin echo (SE) method is shown. On the other hand, in the Tagging Sequence part (T), the spin state is spatially modified. That is, by modifying the spin state from the state in which the phases are aligned to the state in which the phases are spatially different before the application of the imaging pulse sequence, such spins before imaging in the subsequent imaging sequence. It is possible to obtain an image in which the above states are superimposed. How to spatially modify the spin state before imaging depends on the combination of pulses in the Tagging Sequence portion (T).

The waiting time portion (W) is the time from the formation of Tag to the application of an imaging pulse sequence for actually creating an image with Tag. If there is no waiting time portion (W), the state of the spatially modified spin before imaging is directly reflected in the image in the form of Tag. On the other hand, by providing this waiting time, the movement of spins during the waiting time is reflected in the image as Tag distortion. Therefore, by imaging the heart and other organs accompanied by movement by the MR image capturing method with Tag, the movement of the organs can be grasped as distortion of Tag.

Tagging Sequence and Tag Shape Since the Tag shape is determined by the state of the spin before imaging, the Tagging Sequen that spatially modifies the spin.
It is necessary to understand the relationship between the combination of pulses in the ce portion (T) and the shape of Tag. Further, it is necessary to know what determines the number of tags.

The Tagging Sequence (T) shown in FIG. 1 is represented by two RF pulses and one gradient magnetic field pulse added to the phase encode axis. Consider what kind of Tag shape such a combination of pulses creates. FIG. 2A shows the Imaging Sequence of FIG.
It is a pulse sequence for MR image line formation of the phantom image | photographed by the SE method of the part (I). FIG. 2B is the image. The phantom was filled with 10 mMOL copper sulfate solution.

3 (a) and 3 (b) are a tagging sequence portion (T) of a pulse sequence used for imaging and an image, and 15 tags are formed in the horizontal direction of the image. Axel et al. Insert a grid-like Tag in an image by applying such a pulse sequence two-dimensionally. 4A and 4B show the T used by Axel and others.
Tagging Sequ of pulse sequence for capturing images with ag
The ence part and the image photographed by this are shown. As is clear from the pulse sequence of the Tagging Sequence section, a combination of two RF pulses and two gradient magnetic field pulses applied in the uniaxial direction is a continuous sequence. The first two RF pulses and the gradient magnetic field pulse applied on the read axis form 15 tags in the vertical direction of the image, and the two subsequent RF pulses and the gradient magnetic field pulse applied on the phase encode axis Similar to FIG. 3, fifteen tags are formed in the horizontal direction of the image, and as a result, orthogonal lattice-shaped tags are formed.

New Tagging Sequence and Ta of this invention
Since the shape Tag of g is formed by a combination of two RF pulses and one gradient magnetic field pulse, the number of Tag is determined by the strength of the applied gradient magnetic field pulse as long as it takes the form of such a pulse sequence. . Therefore, the number of tags that can be added in the image is MR
It will be limited to the hardware performance of the device.

In the present invention, Tag exceeding the above limit
We are proposing a new Tagging Sequence that can be added. 5 (a) and 5 (b) show this new Tagging Se.
quence and the image taken by this are shown. The difference from the conventional Tagging Sequence is that two gradient magnetic field pulses applied simultaneously with two RF pulses are used for Tag formation. The intensity of the gradient magnetic field pulse on each phase encode axis and the read axis is within the hardware limit of the MR device. Taggin in Figure 5 (a)
The shooting conditions of g Sequence are the same as those in FIG. 3 (partly the same as in FIG. 4), but the number of formed Tag is 2
It is one. Unlike the conventional Tag formation using a gradient magnetic field pulse that is applied only in the one-axis direction, although the Tag direction is inclined by 45 degrees, it is possible to increase the number of Tags. This is done by applying a gradient magnetic field pulse simultaneously in two directions, the phase encode axis and the read axis,
This is because the gradient magnetic field strength felt by the spins is a biaxial vector magnetic field strength, which is twice the number of gradient magnetic field pulses applied when the Tag is tilted 45 degrees in the uniaxial direction. is there. In addition, two such RF
Apply two gradient magnetic field pulses simultaneously with the pulse
In the case of the MR analysis apparatus of the present invention which comprises means,
Relative intensity of each of the two applied gradient magnetic field pulses
The angle of the Tag formed in the image by changing
The degree can be freely set from horizontal to vertical.
The flexibility of the Tag formation angle is, for example, that of the blood flow.
To extract a motion profile in an arbitrary direction such as
Very effective.

Further, in this image formation, it is possible to form a sharper high-speed image by applying a binomial distribution type pulse. Since it becomes sharper as a pulse, it is extremely effective for image formation. Hereinafter, the method, the apparatus, and the effect of the present invention will be described more specifically with reference to examples.

[0018]

EXAMPLE An MR image of the present invention was acquired by photographing based on the above new Tagging Sequence. The MR device used at that time is SIGNA (1.5T) manufactured by GE, USA. FIG. 6 shows the pulse sequence used for the preparation of the cardiac MR image with Tag. As is apparent from FIG. 6, the basic form of the pulse sequence used is the same as that of FIG. 5, but two consecutive pulse groups for inserting Tag orthogonal in directions different by 90 degrees as in the case of FIG. Is used. The first two RF pulses and the phase-encoding axial and read-out axis gradient magnetic field pulses sandwiched between them form a Tag running from the upper left to the lower right in the image, and the next similar pulse group from the upper right to the lower left. A running Tag is formed. The shape and direction of the Tag can be freely changed by changing the flip angle α of the RF pulse and the amplitude and time width of the gradient magnetic field pulse. After Tagging Sequence, an electrocardiogram-gated SE is used to form an image with a certain waiting time.
Method is used. The shooting condition of the SE method is the repetition time (T
R) = 1 time required for one heartbeat, echo time (TE) = 20
ms. The image is an AXIAL image, the matrix size of which is 256 × 128, the slice thickness is 10 mm, and the number of additions is two. The subject was a healthy volunteer, the average heart rate was 62 beats / minute, and the heart rate during the examination was stable. The pulse application was based on the binomial distribution pattern. The captured MR image with Tag is shown in FIGS. 7 and 8. In each, (a) shows the site | part of each imaging | photography cross section. Both are 10 mm apart. (B)-(h) is 7 from end systole to diastole
The number of sheets is 50, and the time interval of each is 50 ms. The reason for choosing this cardiac phase is that we expected the knowledge that would lead to the mechanical expression of the passive diastolic characteristic of the myocardium and the myocardial stress-strain relationship and hardness-stress relationship. The reason why two different cross sections were selected is to know the difference in myocardial wall motion depending on the site.

The following findings can be obtained from FIGS. 7 (b) to 7 (h). (B) Although the right and left ventricles are contracting,
The Tag interval near the apex of the heart is slightly wider than in other cases, and it is presumed that dilation has already started in both the right and left ventricles. (C) It can be understood that the Tag interval at the apex is further widened, and the ventricle is in a dilated state. The myocardial wall near the tricuspid valve on the right ventricular free wall side seems to be moving along the myocardial wall. It is considered to be related to valve movement associated with blood inflow from the right atrium to the right ventricle. In addition, Tag disappears at the apex end of the ventricular septum, and it is expected that the ventricular septum is performing some movement.

(D) Expansion of the right and left ventricles is promoted by the inflow of blood, and it is considered that there is a rapid movement of the myocardium in the region near the tricuspid valve on the right ventricle free wall side and the apex right ventricle side. . However, there is no significant change in the left ventricular free wall. On the other hand, in the interventricular septum, a'twisting 'motion is observed at the apex end and the ventricular base end, and the septal thickness is becoming thin accordingly.

(E) The ventricle is further expanded. In the right ventricle, the movement of the myocardium toward the opposite direction of the ventricle base side and the apex side from the center of the free wall of the right ventricle is observed, and the velocity is also increased. There is no significant change in the wall thickness of the left ventricle, but on the epicardial side of the left ventricle, there is a rotational movement from the apex to the free wall toward the base of the ventricle. No significant movement was seen on the endocardial side. On the other hand, in the interventricular septum, the'twisting 'motion becomes more prominent, and it can be well understood that the anticlockwise rotation is seen from the apex. In addition, the degree of'twisting 'is larger at the base side of the ventricle than at the apex side.

(F) Unlike the slow ventricular dilation shown in (b) to (e) above, a rapid dilation of the ventricle is observed. As a result, in the central part of the free wall of the left ventricle, the movement of the myocardial wall was too fast, and Tag could not follow the change, and it seems that the MR signal disappeared. In the interventricular septum, the'twisting 'movement is more advanced. (G) The ventricle further expands, and along with it, the motion of the wall from the free wall of the right ventricle to the apex becomes more intense. In the left ventricle, the free wall of the left ventricle greatly expands from the center to the base, and the wall thickness there is thin. From the Tag interval, it can be understood that the force is acting from the endocardial side to the epicardial side in the left ventricular free wall. On the other hand, from the center of the free wall of the left ventricle to the apex of the heart, the Tag interval spreads on the endocardial side and no significant change was observed on the epicardial side. It can be read that it is sequentially performed on the adventitia side. The'twist 'of the interventricular septum is further advanced.

(H) The ventricle is further expanded, and the myocardial wall thickness of both the right ventricle and the left ventricle is thin. In addition, the interventricular septum was further'twisted ', and the septal thickness was about half compared with that at the end systole. As the ventricles expand, you can see how the entire myocardial wall is moving. The following findings can be obtained from FIGS. 8 (b) to 8 (h).

(B) Judging from the interval of the Tag of the apex, it is presumed that the dilation of both the right ventricle and the left ventricle has already started. (C) The interval of Tag at the apex is further widened, and the ventricle is expanding. It is expected that there will be a loss of Tag at the mid-ventricular apex end, and a'twisting 'motion has begun in the ventricular septum.

(D) Expansion of the right and left ventricles is promoted by the inflow of blood, and rapid movement of the myocardium is recognized on the epicardial side.
However, no major changes were seen on the endocardial side. In the interventricular septum, a'twisting 'motion is seen in the counterclockwise direction as seen from the apex. (E) The ventricle is further expanded. In the right ventricle, the movement of the myocardium toward the opposite side of the ventricle base side and the apex side from the center of the free wall of the right ventricle is observed. There is no significant change in left ventricular thickness, but there is a rotational movement from the apex to the free wall toward the base of the ventricle on the epicardial side of the left ventricle. The'twist 'movement is more pronounced in the ventricular septum.

(F) A rapid dilation of the ventricles is seen. As a result, in the central part of the left ventricle free wall, the movement of the myocardial wall is too fast, and Tag cannot follow the change.
The signal is missing. The apex end of the septum of the ventricle largely moves to the left ventricle free wall side. In the interventricular septum, the'twisting 'movement is more advanced. (G) The ventricle is further expanded and the myocardial wall is thinned overall. The left ventricle wall not only extends in the cross section in the figure, but the degree of'twisting 'from the top to the bottom in the cross section is slightly reduced near the base of the free wall ventricle.

(H) The volume of the ventricle is slightly reduced, and the thickness of the left and right ventricle walls is slightly increased accordingly. Also, the'twisting 'movements at the base of the left ventricle and in the septum of the ventricle appear to be gradual. As is clear from the above findings, the patterns of myocardial wall motion in FIGS. 7 and 8 were almost the same. However, in detail, it can be said that there is a difference in myocardial wall motion due to the difference in the position of the fault plane. The differences are recognized in the following points.

The'torsion 'motion in the septal ventricle was greater in FIG. 8 than in FIG. In FIG. 7, the “twist” of the ventricular septum was larger on the ventricular base side than on the apex side, whereas in FIG. 8, it was larger on the apex side. All of these seem to be the result of the movement of the myocardial wall at the apex.

On the other hand, in common, the rotational movement of the myocardial wall within the cross section was larger on the epicardial side than on the endocardial side. As described above, by using the pulse sequence for image capturing with Tag of the present invention in the MR apparatus, it becomes possible to know the motion of the myocardial wall through the distortion of Tag. Further, it becomes easy to trace the change in the position of each part of the myocardial wall according to the cardiac time phase, which is far superior to the conventional method for analyzing the motion of the myocardial wall. The MR analysis device of the present invention used in the above example is used.
As described above, the position can be any Tag that is formed in the image.
It can also be set to an angle. For example, FIG. 9 shows a head arrow.
Image of MR-shaped cross section, (a) shows TR / TE = 3
SE image taken at 00/20, (b)-(d) shows TR /
Grazier with horizontal Tag taken at TE = 50/20
It is an und spin echo (GRASS) image. (A) shooting
Under shadow conditions, the anatomical positional relationship is well understood, but the cerebral spine
The cerebrospinal fluid signal is low. On the other hand, (b) to (d) are
A horizontal Tag perpendicular to the flow direction of cerebrospinal fluid is formed in the image.
Tag the flow profile by
It can be known as a distortion. That is, (b)-
Each image in (d) is taken in synchronization with the electrocardiogram,
(B) 100 ms, (c) 4 from the end ventricular systole, respectively
It is an image after 00 ms and (d) 700 ms. Subject
He was a healthy person and had a heart rate of 62 beats / minute. these
Therefore, (b) is the beginning of ventricular diastole, (c) is the end of ventricular diastole.
Phase (d) can be said to be an image at the late ventricular systolic time phase
It From each of these images, the aqueduct, fourth ventricle, and
Looking at the change in Tag near the median mouth, from (b)
Although Tag moves downward in (c),
However, in (d), it is moving upward, and the cardiac phase of cerebrospinal fluid.
You can read the beat according to the time. Similarly, medulla oblongata
Allows anterior vertebral artery blood flow and lateral cerebrospinal fluid flow
Flow visualization is visualized and cannot be measured by ultrasonic waves.
It is possible. In addition, FIG. 10 shows a volunteer volunteer.
M showing an example of blood flow visualization in the deep femoral vein above the lower leg
It is an R image. That is, (a) is a cross section at the upper part of the lower limb
It is an image, (b) ~ (h) by the straight line in (a)
3 is a sagittal cross-sectional image taken along the indicated region. (B) is T
SE image of R / TE = 300/20, (c)-
In (h), a horizontal Tag is added before the shooting conditions in (b).
It is the SE image taken by the sequence. Also, (c) is
The waiting time is zero and the time delay is 50ms or less.
It is an image accompanied by. Each image of these (c) to (h)
Then, only the Tag along the blood vessel will change over time.
I have cancer, but there is no change in Tag in other parts.
Absent. From this, the distortion of Tag reflected blood flow.
It is clear that it is a thing. Also, the distortion of Tag
Since it is a smooth hyperbolic type, blood flow is almost laminar.
It is also understood that the speed is about 2 to 5 mm / s.
Wear. However, such blood flow velocity may vary depending on the location.
What is different can be read from the image of (g). this
As described above, in the MR analysis device of the present invention,
Depending on the elephant, the angle of the Tag formed in the image can be freely set.
Traditionally, like in the example above,
Blood and tissue fluid inside the body, which was difficult to measure accurately,
Measuring the flow with high accuracy through the distortion of Tag
You can

[0030]

As described in detail above, according to the present invention, it becomes possible to insert a plurality of tags in the cross section of the myocardial wall, and thereby the behavior of the myocardium in the cross section is visualized. Furthermore, these data can be used for stress-strain analysis by the finite element method. From the number of tags added to the cross section of the myocardial wall, it becomes easier to estimate the myocardial wall thickness, the wall myocardial weight, and the like. By constructing each cross-sectional image three-dimensionally, it is possible to three-dimensionally display the complicated contraction and expansion dynamics of the heart. Leave in the image
Tag can be formed at any angle,
Clarify the flow of blood, tissue fluid, etc. along the flow direction
Can be visualized.

As a specific effect of these, clear and high-speed image forming MR analysis can be performed. ─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] March 26, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Added

[Correction content]

[Brief description of drawings]

FIG. 9 (a) is an MR image diagram of a sagittal section of the head;
(B)-(d) The MR image figure with the horizontal Tag.

10 (a) is a cross-sectional MR image of the upper part of the lower limb,
(B) A sagittal sectional MR image of the same portion, and (c) to
(H) It is a sagittal cross-section MR image view with a horizontal tag of the same portion.

[Procedure amendment]

[Submission date] March 26, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] Figure 9

[Correction method] Added

[Correction content]

[Figure 9]

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 10

[Correction method] Added

[Correction content]

[Figure 10] ─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] June 24, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 9 (a) is an MR image diagram of a sagittal section of the head;
(B)-(d) The MR image figure with the horizontal Tag.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Added

[Correction content]

[Brief description of drawings]

10 (a) is a cross-sectional MR image of the upper part of the lower limb,
(B) A sagittal sectional MR image of the same portion, and (c) to
(H) It is a sagittal cross-section MR image view with a horizontal tag of the same portion.

Claims (6)

[Claims] 1. An MR analysis method, wherein a plurality of gradient magnetic field pulses are simultaneously applied together with a plurality of RF pulses when forming a Tag. 2. The MR analysis method according to claim 1, wherein the gradient magnetic field pulse is applied simultaneously in two directions of the phase encode axis and the read axis. 3. An MR analysis method which enables high-speed altitude imaging by applying a binomial distribution mode pulse. 4. The MR analysis method according to claim 1, wherein a binomial distribution mode pulse is applied. 5. An MR analysis apparatus comprising means for simultaneously applying two gradient magnetic field pulses together with two RF pulses during Tag formation. 6. An MR analysis apparatus comprising means for applying a binomial distribution mode pulse.