JPH0966046A - Medical image diagnostic equipment - Google Patents

Abstract

(57) Abstract: An accurate OM line is automatically obtained by image processing and a body-axis crossing image parallel to the OM line is captured. An image reconstruction device 1 for reconstructing a median head cross-sectional image along a body axis and a head side cross-sectional image parallel thereto.
7 and a circuit 31 for extracting a human body part from these images
A circuit 32 for obtaining the center of gravity of the midline cross-sectional image of only the human body part, a circuit 33 for detecting the position of the eye based on the distance from the center of gravity to the contour, A circuit 34 that detects the position of the ear canal, a circuit 35 that determines an OM line that connects the position of the eye and the position of the outer ear canal, and a computer 15 that controls to capture a body-axis crossing image parallel to the OM line. Equipped with.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a medical image diagnostic apparatus such as an MR imaging apparatus.

[0002]

2. Description of the Related Art When performing image diagnosis of the head of a subject,
Cross-axis images parallel to the OM line are often used.
That is, a body-axis cross-sectional image parallel to the OM line is extremely important for image diagnosis of the head. The OM line refers to a straight line connecting the eye position and the external ear canal position.

Conventionally, in a medical image diagnostic apparatus such as an MR imaging apparatus, when capturing a cross-body axis image parallel to the OM line, a mid-section image along the body axis of the head is previously captured and this image is obtained. Is displayed on the display screen. Then, an operator such as a doctor observes this image, estimates the position of the eye and the position of the external ear canal on the image, and manually inputs the positions to obtain O.
It defines the M line. And the slice plane is the OM
An MR imaging device or the like is set so as to be a plane parallel to the line, and an image of the cross section is taken.

It has also been proposed that a person does not manually determine an OM line by observing a midsection image, but automatically obtains it by image processing (Tosho et al.,
"Proposal of automatic OM line determination method for head" September 991, Japan Society for Nuclear Magnetic Resonance Medical Society Proceedings, pp. 343).
This is to identify the position of the center of gravity of the median cross-sectional image of the head as the position of the ear.

[0005]

However, if the operator manually inputs the OM line on the displayed image as in the prior art, it is not accurate and the operation is extremely complicated, and the operator has a certain degree of difficulty. There is a problem that the above knowledge and experience are required.

Further, in the automatic OM line determination method as described above, the position of the center of gravity of the median cross-section image of the head is obtained by image processing, and this position is set as the position of the ear. It changes (if the image is from the neck to the shoulder, the center of gravity of the image becomes lower), and it may be greatly affected by individual differences of the subject, which is not accurate.

In view of the above, the present invention provides a medical image diagnostic apparatus capable of automatically and accurately obtaining an OM line without being affected by individual differences and capturing a transverse image parallel to the OM line. With the goal.

[0008]

In order to achieve the above object, in a medical image diagnostic apparatus according to the present invention, an image of a head at a midsection along a body axis of a subject and a head side portion parallel to the image. Means for picking up an image in the cross section, means for obtaining the position of the eye from the median cross-sectional image, means for obtaining the position of the external ear canal from the cross-sectional head side image, the position of the eye and the position of the external ear canal It is characterized in that a means for deciding a line connecting to and as an OM line and a means for picking up a body-axis crossing image of a plane parallel to the decided OM line are provided.

An image of a median cross section of the head along the body axis of the subject and an image of a cross section of the head side parallel thereto are taken. The position of the eye can be obtained by, for example, detecting a concave portion of the contour of the median cross-sectional image of the head.
On the other hand, the image of the cross section of the head side parallel to the midsection of the head shows the external ear canal, but this part is hollow, and the air in the hollow part is caught and earplugs that serve as markers are attached. By doing so, it is possible to distinguish it from other subject parts. Therefore, the position of this external ear canal can be obtained. By connecting the position of the eye and the position of the external ear canal thus obtained, the OM
Can determine the line. If the body axis transverse cross section of the plane parallel to the determined OM line is set as a slice plane and imaging is performed, a body axis transverse image parallel to the OM line can be obtained.

[0010]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an MR imaging apparatus to which the present invention is applied. In FIG. 1, the MR imaging apparatus is 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.

Further, an image processing device 30 is connected to the computer 15. This image processing device 30
Is a human body part extraction circuit 31, a center of gravity calculation circuit 32, an eye position detection circuit 33, an external ear canal position detection circuit 34, and an OM.
And a line determination circuit 35.

First, the head of the subject is MR imaged. At that time, as the imaging slice plane, a midsection along the body axis of the subject's head and a section that cuts both head side portions parallel thereto are set. By this MR imaging, a median cross-section image of the head (sagittal image) along the body axis as shown in FIG.
Then, as shown in (c) and (d) of FIG. 2, a bilateral side image in which the left and right external ear canal images are parallel to the midline cross-sectional image is obtained.

The head midsection image and the head side image parallel thereto are sent to the image processing apparatus 30 via the computer 15. In the image processing apparatus 30, first, as a first step, an operation of extracting a human body part from these images is performed in the human body part extraction circuit 31. In other words, since the values of the obtained data are different between the tissue that constitutes the human body and the other air parts, a predetermined threshold value is set for the pixel data (brightness of the image), and the brightness of each pixel is higher than this. Whether it is low or not is determined, and the human body part and the other part (air part) are separated. As a result, it is possible to obtain an image of only the human body part 41 as shown in (a), (c) and (d) of FIG.

Next, in the second step, the center of gravity calculation circuit 32 finds the luminance center of gravity of the extracted median cross-sectional image of only the human body portion 41. From the pixel value distribution in the human body part 41, the center of gravity for the pixel value is calculated. As a result, the center of gravity 42 as shown in FIG.

In the third step, as shown in FIG. 2B, the eye position 43 is focused on the distance from the image center of gravity 42 to the end (outline) of the human body portion 41 of the median section image.
Is required. This is performed by the eye position detection circuit 33. That is, since the eye is recessed, the recessed portion can be detected by searching for a place where the distance from the image center of gravity 42 to the contour is the shortest.

In the fourth step, the external ear canal position detection circuit 34 extracts the outside of the two-head side images ((c) and (d) in FIG. 2) extracted as described above to form only the human body part 41. The ear canal portion 44 is detected and its position is obtained. The external ear canal portion 44 is shown in the two-head side image, but since the external ear canal portion 44 is air, the brightness (pixel data) is low. Therefore, by extracting only the human body portion 41, a donut-shaped image can be obtained, and the hollow portion can be easily obtained, and the obtained portion becomes the external ear canal portion 44.

In the fifth step, the position 45 of the external ear canal thus obtained is superimposed on the median cross-sectional image as shown in FIG. 45 and 45 are connected by a straight line 46 on the image of the midsection. This straight line 46 becomes the OM line. Such processing is performed by the OM line determination circuit 35.

When the OM line is determined in this way, information indicating it is sent from the image processing apparatus 30 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. 3 is captured.

Before performing the human body part extracting operation in step 1 above, an appropriate preprocessing filter may be applied to the image data. This makes it possible to more accurately extract the human body part while avoiding the influence of noise and 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.

When MR imaging is first performed to obtain a median cross-sectional image of the head and side-by-side images of the left and right external ear canals that are parallel to the image, high brightness is obtained on the image. It is also possible to attach such markers to the subject instead of earplugs. In this case, in step 4, the outer ear canal position is detected by detecting the high-luminance position by the outer ear canal position detection circuit 34.

Further, although the image processing apparatus 30 is configured as hardware in the above, it may be configured 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.

[0024]

As described above, according to the medical image diagnostic apparatus of the present invention, it is only necessary to capture the midline cross-sectional image of the head along the body axis of the subject and the side image of the head parallel thereto.
Automatically find accurate OM line from those images,
A body-axis crossing image parallel to the OM line can be captured. Therefore, the operation is extremely simple, and moreover, it is possible to accurately obtain a body-axis crossing image parallel to the OM line.

[Brief description of drawings]

FIG. 1 is a block diagram of an MR imaging apparatus according to the present invention.

FIG. 2 is a diagram illustrating an operation of obtaining a median cross-sectional image of a head along a body axis, a head side image parallel to the image, and an OM line.

FIG. 3 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 Reconstructing Device 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 External ear canal position detection circuit 35 OM line determination circuit 41 Human body part of image 42 Center of gravity of image 43 Eye position 44 External ear canal part 45 External ear canal position 46 OM line

Claims (1)

[Claims] 1. A means for picking up an image of a head in a median cross section along a body axis of a subject and an image of a cross section of a side of the head parallel thereto, and a means for obtaining an eye position from the median cross section image. And a line connecting the position of the eye and the position of the external ear canal with a means for obtaining the position of the external ear canal from the head side sectional image.
A medical image diagnostic apparatus comprising: a unit that determines a line and a unit that captures a cross-body-axis image of a plane parallel to the determined OM line.