JPH05317288A - Mri device having outline extracting function - Google Patents

Abstract

PURPOSE:To obtain the MRI device having an outline extracting function which can extract an outline with high accuracy on an MRI image by constituting the device so that outline point candidate data is extracted with regard to a second MRI image by a correlation to border line data of an object subjected to manual input onto a first MRI image by a user. CONSTITUTION:An MRI image of a first frame is displayed to a user, and the user is allowed to trace it by a mouse operation. Subsequently, by setting a first frame as a first image, the centroid G of an area surrounded by border line data R on a first image, plural radial directions Gi in which it is an origin, and a reference range Ui are determined. Next, the next frame of the frame of a first image is set as a second image, and G, Gi and Ui corresponding to a first image are taken thereon. Also, a correlation between image data Di of a first image and a second image is taken, a point on a second image corresponding to an outline point Ri of a first image is derived and it becomes an outline point candidate Ri. When its difference is within an allowable range delta, the outline point candidate Ri is decided definitely as the outline point Ri.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an MRI apparatus having a contour extracting function, and is particularly useful for diagnosis of heart disease.

[0002]

BACKGROUND OF THE INVENTION Chest MR for diagnosing heart disease.
I images are continuously picked up by the FE method (Field Echo method),
Observation of the movement of the myocardial wall is performed. In order to facilitate the observation of the movement of the myocardial wall, it is desirable that the MRI apparatus has a function of automatically extracting the myocardial wall from the MRI image. However, conventionally, an M equipped with such a function
RI machines are not known.

[0003]

FE method (Field Echo)
On the MRI image of the chest obtained by the method), the part of the myocardial wall becomes black and the part of the blood flow surrounded by the myocardial wall becomes white. Therefore, if the outline of the white part on the MRI image can be extracted, the same effect as the extraction of the myocardial wall can be obtained. By the way, although various contour extraction techniques are known in the field of image processing, when such a contour extraction technique is applied to an MRI image, the MRI image is an image with a delicate gradation.
The accuracy is poor and not practical. Therefore, it is an object of the present invention to provide an MRI apparatus having a contour extraction function that enables accurate contour extraction on an MRI image.

[0004]

According to the present invention, a plurality of MRI images of the same object taken at different times or a plurality of MRI images of the same object taken in different adjacent regions are displayed on a first MRI image. A contour manual input means for a user to manually input the contour of the target, a relatively narrow range of data including the manually input contour portion of the data of the first MRI image, and a second MRI image Correlation calculation means for extracting contour point candidate data on the second MRI image by correlation with a relatively wide range of data including the manually input contour portion among the data of 1. A contour point determining means for extracting contour point data from the contour point candidate data, and a contour generating means for generating a target contour on the second MRI image by interpolation from the contour point data. M having the outline extraction function, wherein
An RI device is provided.

[0005]

In the MRI apparatus having the contour extracting function of the present invention, the contour point candidate data for the second MRI image is extracted by the correlation with the contour data of the target manually input by the user on the first MRI image. .. Therefore, the contour recognition of the user is reflected in the contour point candidate data of the second MRI image, but the user can accurately recognize the contour of the MRI image with a delicate gradation, so that the contour point of the second MRI image is recognized. The candidate data will be highly accurate. Further, since the contour point data is extracted by evaluating the contour point candidate data on the basis of the characteristic of the object such as the movable range of the heart wall, the contour line data is also accurate. Then, the contour of the target obtained by interpolation from the contour point data has high accuracy.

Thus, a plurality of MRI images of the same object taken at different times, or a first MRI in a plurality of MRI images of the same object taken at different sites close to each other.
If the user manually inputs the contour of the target on the image, the contour of the target can be automatically and accurately displayed on other MRI images.
Will be obtained.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail based on the embodiments shown in the drawings. However, this does not limit the present invention. FIG. 1 is a block diagram of an MRI apparatus 1 having a contour extracting function according to an embodiment of the present invention. The computer 2 controls the overall operation based on instructions from the mouse 14 and the console 13. The sequence controller 3 operates the gradient magnetic field driving circuit 4 based on the stored sequence, and causes the static magnetic field coil and the gradient magnetic field coil of the magnet assembly 5 to generate a static magnetic field and a gradient magnetic field. Further, it controls the gate modulation circuit 7 to modulate the RF pulse generated by the RF oscillation circuit 6 into a predetermined waveform,
From the RF power amplifier 8 to the transmitter coil of the magnet assembly 5.

The NMR signal obtained by the receiving coil of the magnet assembly 5 is input to the phase detector 10 via the preamplifier 9 and further to the computer 2 via the AD converter 11. The computer 2 reconstructs an image based on the data of the NMR signal obtained from the AD converter 11, and displays it on the display device 12.

2 and 3 are flow charts of the contour extracting operation of the MRI apparatus 1. In addition, here, a plurality of MRs
As the I image, an MRI moving image of the heart taken by the FE method is assumed. Further, the left ventricle inner wall is assumed as the target of contour extraction.

In step S1, the MR of the first frame
The I image is displayed to the user, and the user is made to trace the wall of the left ventricle by operating the mouse. Since the user can accurately recognize the contour even by using MRI images with delicate gradations,
The data of the contour line indicating the inner wall of the left ventricle (contour line data) is input without error. When the user gives an instruction to end the input from the console 13, the process proceeds to step S2. Step S2
Then, the first frame is set as the first image, and the process proceeds to step S3.

In step S3, as shown in FIG. 4, the center of gravity G [1] of the area surrounded by the contour line data R [1] on the first image is calculated. In step S4, as illustrated in FIG. 5, a plurality of radial directions Gi [1] (i = 1, 2, ...) Starting from the center of gravity G [1] on the first image are determined.

In step S5, as illustrated in FIG. 6, an appropriate section before and after the contour point Ri [1] on the radial direction Gi [1] of the first image is set as the reference range Ui [1]. The reference range Ui [1] may be set in consideration of the characteristics of the target of contour extraction (here, the left ventricle inner wall) (here, the width of the characteristic portion before and after the left ventricle inner wall).

In step S6, the frame next to the frame of the first image is set as the second image, and the process proceeds to step S7. In step S7, the center of gravity corresponding point G [2] geometrically corresponding to the center of gravity G [1] on the first image is set on the second image. In step S8, as shown in FIG. 7, the radial direction Gi [1] geometrically corresponding to the radial direction Gi [1] on the first image.
Take [2] on the second image. In step S9, as illustrated in FIG. 8, a contour point Ri [1/2] geometrically corresponding to the contour point Ri [1] of the first image in the radial direction Gi [2] of the second image. Then, an appropriate section before and after that is set as a reference range Ui [2]. The reference range Ui [2] is
It may be determined in consideration of the characteristics of the target of contour extraction (here, the left ventricle inner wall) (here, the width of motion of the left ventricle inner wall).

Proceeding to FIG. 3, in step S10, as shown in FIG. 9, image data Di [1] of the reference range Ui [1] in the radial direction Gi [1] on the first image ((a in FIG. 9)). ))
And the reference range Ui in the radial direction Gi [2] on the second image
The second corresponding to the contour point Ri [1] of the first image by correlating with the image data Di [2] of [2] ((b) of FIG. 9).
A point on the image is obtained and used as a contour point candidate Ri [2].

In step S11, as shown in FIG. 10, the difference Vi between the contour point Ri [1] on the first image and the contour point candidate Ri [2] on the second image is the object (here, the left ventricle inner wall). 2) within the allowable range δ based on the characteristics (here, the motion of the left ventricle inner wall is expanded or contracted, how much is displaced between frames, how much error, etc.), the contour point candidate on the second image Ri [2] is a contour point Ri on the second image.
It is confirmed as [2] (in the case of (a) of FIG. 10). If it is outside the allowable range δ, the contour point candidate Ri on the second image
Discard [2] (in the case of FIG. 10B). As a result, as shown in FIG. 11, the contour point R1 is displayed on the second image.
[2], R2 [2], ... Are obtained.

In step S12, as shown in FIG. 12, the contour points R1 [2], R2 [2], ... On the second image are connected by cubic spline interpolation, and the contour line data R [on the second image is connected. 2]. In step S13, a point corresponding to the contour point candidate Ri [2] discarded in step S11 is selected from the contour line data R [2], and the contour point Ri is selected.
Add as [2].

In step S14, it is checked whether or not there is a next frame. If not, the process ends. If there is, the process proceeds to step 15. In step 15, the second image is set as the new first image, and the process returns to step S3.

As described above, according to the MRI apparatus 1 described above, since the contour recognition of the target by the user is reflected and the characteristics of the imaging target are taken into consideration, the contour can be extracted with high accuracy.

In the above embodiment, the contour extraction of the inner wall of the left ventricle has been described as a specific example, but the present invention is also applicable to the contour extraction of the kidney, the brain and the like. In addition, for example, it is also applicable to extract the contour of the target from a plurality of MRI images by multi-slice (a plurality of MRI images of the same target taken at different adjacent positions). further,
Not only two-dimensional contour extraction but also three-dimensional contour extraction can be applied.

[0020]

The MRI having the contour extracting function of the present invention
According to the apparatus, since the contour recognition of the target by the user is reflected and the characteristics of the target are taken into consideration, the contour can be extracted with high accuracy, which is particularly useful for the diagnosis of heart disease.

[Brief description of drawings]

FIG. 1 is a block diagram of an MRI apparatus having a contour extracting function that is an embodiment of the present invention.

FIG. 2 is a flowchart showing a contour extracting operation.

FIG. 3 is a subsequent flowchart of the contour extracting operation.

FIG. 4 is an exemplary diagram of contour line data input by a user.

FIG. 5 is an exemplary view of a radiation direction on a first image.

FIG. 6 is a view showing an example of a reference range on the first image.

FIG. 7 is an exemplary diagram of a radiation direction on a second image.

FIG. 8 is an exemplary diagram of a reference range on a second image.

FIG. 9 is an explanatory diagram of a correlation calculation between image data.

FIG. 10 is an explanatory diagram of evaluation of contour point candidate data.

FIG. 11 is a view showing an example of contour points on a second image.

FIG. 12 is a view showing an example of contour line data on a second image.

[Explanation of symbols]

 1 MRI device 2 computer 12 display device 14 mouse Di [1], Di [2] image data G [1] barycenter G [2] barycenter corresponding points R [1], R [2] contour line data Ri [1], Ri [2] Contour point Ui [1] Reference range Ui [2] Reference range

Claims (1)

[Claims] 1. An outline of an object is displayed by a user on a first MRI image in a plurality of MRI images of the same object taken at different times or a plurality of MRI images of the same object taken at different sites close to each other. Contour manual input means for manually inputting, data of a relatively narrow range including the manually input contour portion of the data of the first MRI image, and second M
The second MR is obtained by correlation with a relatively wide range of data including the manually input contour portion of the RI image data.
Correlation calculation means for extracting contour point candidate data on the I image, contour point determining means for extracting contour point data from the contour point candidate data by evaluation based on characteristics of the object, and second by interpolation from the contour point data An MRI apparatus having a contour extracting function, comprising: a contour generating unit that generates a target contour on the MRI image.