JPH0966047A - Medical image processing equipment - Google Patents

Abstract

(57) Abstract: An accurate OM line is automatically obtained by image processing using only a mid-section image of a head. A circuit 31 for extracting a human body part from a median cross-section image of a head along a body axis, a circuit 32 for calculating a center of gravity of a median cross-section image of only a human body part, and a distance from the center of gravity to a contour The circuit 33 that detects the position of the eye, the circuit 34 that detects the upper position of the oblique platform as the external ear canal position by capturing the oblique platform shown in the midline cross-sectional image, and the position of the eye and the position of the external ear canal are connected. And a circuit 35 for determining the OM line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a medical image processing apparatus for processing medical images such as MR images and X-ray CT images, and more particularly to a medical image processing apparatus for automatically determining a head OM line from those images.

[0002]

2. Description of the Related Art The OM line refers to a straight line connecting the position of the eye and the position of the external ear canal. Conventionally, a doctor or the like observes a midsection image along the body axis of the head, A general method is to judge the position of the eye and the position of the external ear canal on the image and manually input the OM line.

On the other hand, by performing image processing on a median cross-section image along the body axis of the head, the center of gravity of the image is specified as the position of the ear, and thereby the OM line is automatically determined. (See No. Noboru et al., “Proposal of Automatic Determination Method for Head OM Line,” September 1991, Proceedings of the Annual Meeting of the Japanese Society for Nuclear Magnetic Resonance Medicine, page 343).

[0004]

However, when a doctor or the like observes the displayed image as in the prior art, the O
When determining the M line, there is a problem that positioning of the OM line tends to be inaccurate, complicated and not easy, and a certain level of knowledge or experience is required.

In addition, OM is performed by the image processing as described above.
In the method of automatically determining the line, the image center of gravity is simply set as the position of the ear, which is convenient.
Not accurate. That is, it changes depending on the range of the human body in the image. In other words, if the shoulder is visible, the center of gravity is on the lower side. Conversely, if the neck is barely visible and only the top of the head is present, the center of gravity is on the upper side. Furthermore, there are circumstances in which it is greatly affected by individual differences among examinees.

In view of the above, an object of the present invention is to provide a medical image processing apparatus capable of automatically obtaining an accurate OM line by image processing.

[0007]

To achieve the above object, in a medical image processing apparatus according to the present invention, means for extracting a subject portion in a midline cross-sectional image of the head along the body axis of the subject, Means for obtaining the image center from the center of gravity of the extracted image, means for obtaining the eye position by the distance from the image center to the extracted image contour, and detecting the upper position of the oblique platform by catching the oblique platform near the image center And a means for determining the line connecting the eye position and the upper position of the sloping platform as the OM line.

The upper position of the swash plate almost coincides with the position of the external ear canal, and there are few individual differences. On the other hand, this slant is M
On the R image, it appears as a high-luminance portion near the center of the head. Therefore, it is easy to detect the center of the image from the center of gravity of the image and detect a portion having high brightness near the center of the image, whereby the position of the upper part of the slant base can be regarded as the position of the external ear canal.

On the other hand, the eye part is dented, so that the distance from the center of the image to the contour of the image is the shortest. Therefore, by utilizing this, the position of the eye can be obtained from the distance from the center of the image to the contour. In this way, the position of the eye and the position of the external ear canal can be grasped,
An OM line can be defined by connecting these.

[0010]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a medical image processing apparatus 30 to which the invention is applied. The image processing device 30 includes a human body part extraction circuit 31, a center of gravity calculation circuit 32, an eye position detection circuit 33, an upper position detection circuit 34 of a slanting platform, and an OM line determination circuit 35. When the MR image of the median cross-section image along the body axis of the head is input to the image processing device 30, the OM line is automatically determined by each of the circuits described above.

The image processing apparatus 30 can also be used by incorporating it in an MR imaging apparatus as shown in FIG. This MR imaging device includes a static magnetic field generator 11
And a gradient magnetic field generator 12, a transmitter 13, and a receiver 14. A subject (not shown) is placed in the static magnetic field generated by the static magnetic field generator 11, a pulse-shaped gradient magnetic field is generated by the gradient magnetic field generator 12, and this gradient magnetic field is superimposed on the static magnetic field. At the same time, the transmitter 13 transmits a high frequency signal to the subject. Then, the NMR signal generated in the subject is received by the receiving device 14, and the raw data is taken into the computer 15 and stored in the memory 16.

The computer 15 is a gradient magnetic field generator 1
2. By controlling the transmitting device 13, the receiving device 14, etc., an imaging sequence such as a gradient echo method or a spin echo method is performed, and the raw data on a predetermined slice plane obtained there is stored in the memory 16. The image reconstructing device 17 reconstructs a tomographic image on the slice plane by two-dimensional Fourier transforming the raw data on the memory 16. The reconstructed image data is stored in an external recording device 18 such as a hard disk.

The computer 15 includes a display control circuit 21.
The display device 22 is connected through the display device 22 and the above-mentioned reconstructed image and the like are displayed. Further, a mouse 23 and a keyboard 24 are connected so that coordinates and commands can be input.

In such an MR imaging apparatus, MR imaging of the subject's head is performed, and a median cross-sectional image (sagittal image) along the body axis of the head is obtained as shown in FIG. The image of the midline cross section of the head is sent to the image processing apparatus 30 by the computer 15. Then, in the image processing device 30, first, the first step is the human body part extraction circuit 3
Performed by 1. In the MR image, the value of data (pixel value) obtained differs between the tissue that constitutes the human body and the other air portion. Therefore, the human body part extraction circuit 31 sets a predetermined threshold value for pixel data (brightness of image) and determines whether the brightness of each pixel is higher or lower than that, and determines the human body part and other parts. And the part (air part). As a result, an image of only the human body part 41 as shown in FIG. 3A can be obtained.

Next, the center of gravity calculating circuit 32 obtains the luminance center of gravity of the image of the median cross-section which has been extracted and has only the human body portion 41 (second step). This is to calculate the center of gravity related to the pixel value from the pixel value distribution in the human body part 41, and, for example, FIG.
A center of gravity 42 as shown in is obtained. The image center of gravity 42 is treated as the image center.

After that, the eye position detection circuit 33 carries out a third step to obtain the eye position 43 as shown in FIG. 3 (b). Since the eye is hollow, the distance from the image center 42 to the contour of the image is shortest in the hollow eye portion. Therefore,
The position 43 of the eye can be obtained by calculating the distance from the image center 42 to the end (outline) of the human body part 41 of the median cross-section image and searching for the place with the shortest distance.

Next, as a fourth step, the swash table upper position detection circuit 34 detects the swash table upper position. The slope is
On the MR image, it appears as a high brightness portion near the center of the head. Therefore, as shown in (c) of FIG. 3, it is possible to detect a portion having high brightness near the image center 42 of the median cross-section image of the head as the slant base 44. Then, the upper position of the slant base 44 is regarded as the external ear canal position 45.
The upper position of the slope is almost the same as the position of the external ear canal, and there are few individual differences.

In the fifth step, as shown in FIG. 3D, a straight line 46 connects the position 45 of the ear canal obtained and the position 43 of the eye previously obtained. This straight line 46 is OM
Become a line. Such processing is performed by the OM line determination circuit 3
5 is performed.

In the MR imaging apparatus shown in FIG. 2,
When the image processing apparatus 30 obtains the OM line in this manner, the information is returned to the computer 15. The computer 15 determines each imaging parameter so that the body-axis transverse section parallel to the OM line becomes the imaging slice plane, and MR imaging is performed according to it. As a result, an image (transverse image) of the transverse section of the body axis parallel to the OM line as shown in FIG. 4 is captured. Alternatively, since three-dimensional data is already obtained in the recording device 18, for example, a large number of adjacent median cross-section images are obtained, and the whole of these data represents a three-dimensional volume. If so, by extracting and arranging data (on the image reconstructing device 17 or the computer 15) that fits on the cross-section of the body axis parallel to the obtained OM line from the data, the OM line is obtained. It is also possible to obtain images in parallel body-axis cross sections.

In the image processing apparatus 30, an appropriate preprocessing filter may be applied to the image data before performing the human body part extracting operation in step 1 above. This makes it possible to more accurately extract the human body part while avoiding the influence of noise and the like. Similarly, when the slant base 44 is detected in step 4, it is possible to apply an appropriate pre-processing filter to avoid the influence of noise or the like. Further, the operation of extracting the human body part was performed using the threshold value, but it is also possible to extract it by another method such as the region row method.

Further, although the image processing apparatus 30 is constructed as hardware in the above, it may be constructed as software. In that case, the image processing apparatus 30 can be configured as dedicated hardware that performs the above steps by software, and the image processing apparatus 30 does not need to be used as such dedicated hardware in the computer 15. It is also possible to perform it by software processing.

[0022]

As described above, according to the medical image processing apparatus of the present invention, an accurate OM line can be automatically obtained from the image of the midline cross section of the head along the body axis of the subject. Therefore, the operation for obtaining the OM line is extremely simple, and the skill or experience of the operator is unnecessary. This medical image processing apparatus, when combined with an MR imaging apparatus, automatically obtains an accurate OM line only by capturing a median cross-sectional image of the head, and a body axis cross-sectional image parallel to the OM line. Can be automatically imaged.

[Brief description of drawings]

FIG. 1 is a block diagram of an image processing apparatus according to the present invention.

FIG. 2 is a block diagram of an MR imaging apparatus including the above image processing apparatus.

FIG. 3 is a diagram illustrating an operation of obtaining a median cross-sectional image of a head and an OM line along a body axis.

FIG. 4 is a diagram showing an example of a body-axis crossing image.

[Explanation of symbols]

 11 Static Magnetic Field Generator 12 Gradient Magnetic Field Generator 13 Transmitter 14 Receiver 15 Computer 16 Memory 17 Image Reconstructor 18 Recording Device 21 Display Control Circuit 22 Display Device 23 Mouse 24 Keyboard 30 Image Processing Device 31 Human Body Part Extraction Circuit 32 Centroid Calculation circuit 33 Eye position detection circuit 34 Oblique platform upper position detection circuit 35 OM line determination circuit 41 Human body part of image 42 Image center of gravity 43 Eye position 44 Oblique platform 45 Oblique platform upper position 46 OM line

Claims (1)

[Claims] 1. A means for extracting a subject portion in a midline cross-sectional image of the head along the body axis of the subject, a means for obtaining an image center from the center of gravity of the extracted image, and an extracted image contour from the image center. Means for obtaining the position of the eye from the distance of the eye, means for detecting the upper position of the slant by grasping the slant near the center of the image, and the line connecting the eye position and the upper position of the slant as the OM line. A medical image processing apparatus comprising: a determining unit.