JP2013052121A - Medical image processor and medial image processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a medical image processor which automatically form a suitable image to read the image of spine (especially a vertebral body and vertebral foramen) and display the image.SOLUTION: A medical image processor 1 calculates a straight line L which extends to the anteroposterior direction of a subject and passes through a vertebral foramen 4 to each tomographic image (S2), calculates Y coordinates Ya, Yb at the end points of the vertebral body 3 on the straight line L (S3), calculates a point α which externally divides the line between two end points of the vertebral body 3 positioned at the ventral side on the straight line L (S4), calculates a point β which externally divides the line between two end points of the vertebral body 3 positioned at the back side on the straight line L (S5), calculates the central point γ between α and β (S6), calculates a base line Lα passing through all the points α, a base line Lβ passing through all the points β, and a base line Lγ passing through all the points γ (S9), and uses any of base lines Lα, Lβ, Lγ to form a vertebral image (S10).

Description

  The present invention relates to a medical image processing apparatus that performs image processing on medical images such as CT images, MR images, and US images. Specifically, the present invention relates to an image processing technique for creating and displaying an image relating to the spine.

  Conventionally, diagnosis using medical images such as CT (Computed Tomography) images, MR (Magnetic Resonance) images, US (Ultrasound) images, and the like has been performed. In recent years, an image processing technique for creating and displaying an image suitable for interpreting a desired tissue has been developed and studied.

  For example, Non-Patent Document 1 describes that examination of the state of nerves passing through the spine (vertebra) is effective for disc herniation, spinal stenosis, spondylolysis and spondylosis, etc. . In intervertebral disc herniation, due to the degeneration of the intervertebral disc between the vertebrae, a portion of the intervertebral disc that protrudes backward (the nucleus pulposus or annulus fibrosus) causes pain because it compresses the nerve (root). In spinal canal stenosis, for various reasons, the place where the nerves of the spinal vertebral foramen wrapped in the dural tube pass (the spinal canal) becomes narrow, causing pain and numbness in the lower limbs and gait disturbance . A medical technique (referred to as myelography) described in Non-Patent Document 1 is to examine a change in shadow by putting a contrast medium reflected in X-rays at a cerebrospinal fluid in the cerebral spine.

  Patent Document 1 describes an image processing apparatus that extracts a vertebral body region from a medical image. In the image processing apparatus described in Patent Literature 1, body regions are extracted from a series of tomographic images of a subject, and a region of interest including a vertebral body region is set from the extracted body regions. Then, for each pixel in the region of interest, a vertebral body (bone) region is extracted by performing threshold processing using the threshold value as the CT value of cancellous bone.

JP 2010-246661 A

Naruo Orthopedic Hospital “Representative Diseases Recognized by Myelography” is Kanzan Communication No. 20 2001 (http://www.naruoseikei.com/hakuzan/20/20.html 2011 (Search August 24)

  However, in the X-ray image taken in the conventional myelography, organs and parts other than the desired object are also taken together, which is difficult to diagnose.

  Here, the desired object in the present application is, in particular, a vertebral body or a vertebral hole. The vertebral body is a columnar part located in front of the vertebra (ventral side). A vertebral foramen is a space located behind the vertebral body as viewed from the front of the human body. A number of vertebral bodies are connected, and when the vertebral foramina overlaps, it becomes a tube. This tube is called the spinal canal, and the spinal cord and cauda equina pass through the spinal canal.

  If the technique described in Patent Document 1 is applied to the image creation processing of a vertebral foramen, a vertebral foramen region is extracted by performing threshold processing using the threshold value as the CT value of the vertebral foramen. However, in each tomographic image, there may be a portion where the boundary between the vertebral foramen region and other tissues or parts cannot be determined, and the vertebral foramen region may not be automatically extracted as a closed region.

  Further, an image processing technique for automatically creating and displaying an image suitable for interpretation of the spine (particularly vertebral body and vertebral foramen) has not been established yet.

  The present invention has been made in view of the above-described problems, and its purpose is to automatically create and display an image suitable for interpreting the spine (particularly vertebral bodies and foramen). An image processing apparatus or the like is provided.

  In order to achieve the above-described object, a first invention is a medical image processing apparatus that creates a spine image from a plurality of tomographic images, and in a single tomographic image, extends in the front-rear direction of the subject, A first straight line passing through the first vertebral body, a first vertebral body first end point and a second end point on the first straight line, and a reference point based on the first end point and the second end point. Means for calculating the reference point in a plurality of tomographic images, calculating a reference line passing through all the reference points, and means for creating the spine image using the reference line. Is a medical image processing apparatus characterized by

  The second invention is a medical image processing apparatus for creating a spine image from a plurality of tomographic images, and means for calculating a first straight line extending in the front-rear direction of the subject and passing through the vertebral foramen in the plurality of tomographic images. And means for calculating a center line passing through the centers of a plurality of vertebral bodies in a curved cross-section reconstructed image composed of a plurality of pixels of the first straight line group, and a vertical direction of the center line at each point of the center line Or means for calculating a second straight line extending in the front-rear direction of the subject, means for calculating the first end point and the second end point of the vertebral body on the second straight line, and the first end point and the second end point A reference point is calculated based on a plurality of tomographic images, the reference point is calculated in a plurality of tomographic images, a reference line passing through all the reference points, and the spine image is created using the reference line. And a medical image processing characterized by comprising: It is a device.

  A third invention is a medical image processing method for creating a spine image from a plurality of tomographic images, and calculates a first straight line that extends in the front-rear direction of a subject and passes through a vertebral fora in a single tomographic image. A step of calculating a first end point and a second end point of the vertebral body on the first straight line, a step of calculating a reference point based on the first end point and the second end point, and a plurality of tomographic images A medical image processing method comprising: calculating the reference point; calculating a reference line passing through all the reference points; and creating the spine image using the reference line. is there.

  The fourth invention is a medical image processing method for creating a spine image from a plurality of tomographic images, the step of calculating a first straight line extending in the front-rear direction of the subject and passing through the vertebral foramen in the plurality of tomographic images. Calculating a center line passing through the centers of a plurality of vertebral bodies in a curved cross-section reconstructed image composed of a plurality of pixels of the first straight line group, and a vertical direction of the center line at each point of the center line Alternatively, a step of calculating a second straight line extending in the front-rear direction of the subject, a step of calculating the first end point and the second end point of the vertebral body on the second straight line, and the first end point and the second end point are calculated. A reference point is calculated based on the step, the reference point is calculated in a plurality of tomographic images, a reference line passing through all the reference points is calculated, and the spine image is created using the reference line. Including steps A medical image processing method according to claim.

  According to the present invention, it is possible to provide a medical image processing apparatus or the like that automatically creates and displays an image suitable for interpretation of a spine (particularly a vertebral body or a foramen).

The figure which shows the hardware constitutions of a medical image processing apparatus Flow chart showing first spine image creation processing The figure explaining the 1st spine image creation processing Flow chart showing second spine image creation processing The figure explaining the 2nd spine image creation processing The figure explaining the creation processing of the minimum value projection image The figure explaining the creation processing of the minimum projected image using the approximate projection plane Examples of spine images Examples of spine images Diagram for explaining development image creation processing The figure explaining the creation process of the expansion | deployment image using an approximate projection surface Example of unfolded image Example of display screen Reference line display example Reference line display example The figure explaining 1st reference line correction processing The figure explaining 1st reference line correction processing The figure explaining 2nd reference line correction processing

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First, a hardware configuration of the medical image processing apparatus 1 according to the present invention will be described with reference to FIG.

  As shown in FIG. 1, a display device 17, an input device such as a mouse 18 and a keyboard 19, etc. are connected to the medical image processing device 1. The medical image processing apparatus 1 may be connected to an image database 21, a medical image photographing apparatus 22, and the like via the network 20.

The medical image processing apparatus 1 is a computer that performs processing such as image generation and image analysis.
As shown in FIG. 1, the medical image processing apparatus 1 includes a CPU (Central Processing Unit) 11, a main memory 12, a storage device 13, a communication interface (communication I / F) 14, a display memory 15, a mouse 18, a keyboard 19, and the like. The external device has an interface (I / F) 16, and each unit is connected via a bus 10.

  The CPU 11 calls and executes a program stored in the main memory 12 or the storage device 13 in the work memory area on the RAM of the main memory 12, executes drive control of each unit connected through the bus 10, and performs medical image processing. Various processes performed by the device 1 are realized.

  The main memory 12 includes a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The ROM permanently holds a computer boot program, a program such as BIOS, data, and the like. The RAM temporarily stores programs, data, and the like loaded from the ROM, the storage device 13, and the like, and includes a work area that the CPU 11 uses to perform various processes.

  The storage device 13 is a device that reads and writes data from and to an HDD (hard disk drive) and other recording media, and stores a program executed by the CPU 11, data necessary for program execution, an OS (operating system), and the like. As for the program, a control program corresponding to the OS and an application program are stored. Each of these program codes is read by the CPU 11 as necessary, transferred to the RAM of the main memory 12, and executed as various means.

The communication I / F 14 includes a communication control device, a communication port, and the like, and mediates communication between the medical image processing apparatus 1 and the network 20. The communication I / F 14 controls communication with the image database 21, another computer, or a medical image capturing apparatus 22 such as an X-ray CT apparatus or an MRI apparatus via the network 20.
The I / F 16 is a port for connecting a peripheral device, and transmits / receives data to / from the peripheral device.

  The display memory 15 is a buffer that temporarily accumulates display data input from the CPU 11. The accumulated display data is output to the display device 17 at a predetermined timing.

  The display device 17 includes a display device such as a liquid crystal panel and a logic circuit for executing display processing in cooperation with the display device, and is connected to the CPU 11 via the display memory 15. The display device 17 displays the display data stored in the display memory 15 under the control of the CPU 11.

The mouse 18 and the keyboard 19 output various instructions and information input by the operator to the CPU 11. The operator interactively operates the medical image processing apparatus 1 using external devices such as the mouse 18 and the keyboard 19.
The display device 17 and the input device (the mouse 18 and the keyboard 19) may be integrated, for example, as a display with a touch panel. In this case, the keyboard layout of the keyboard 19 may be displayed on the display with a touch panel.

  The network 20 includes various communication networks such as a LAN (Local Area Network), a WAN (Wide Area Network), an intranet, and the Internet, and mediates communication connection between the image database 21 and other information devices and the medical image processing apparatus 1. To do.

  The image database 21 accumulates and stores image data captured by the medical image capturing device 22. In the example shown in FIG. 1, the image database 21 is connected to the medical image processing apparatus 1 via the network 20, but the image database 21 is provided in, for example, the storage device 13 in the medical image processing apparatus 1. Also good.

  Here, the positional relationship of each part of the spine will be described with reference to FIG. In the embodiment of the present invention, a CT image will be described as an example of a medical image. FIG. 5A is a CPR (Curved Planar Reconstruction) image in which the horizontal axis is the front-rear direction (Y-axis direction) of the subject and the vertical axis is the body axis direction (slice direction). In FIG. 5 (a), pixels having CT values similar to bones (including vertebral bodies, vertebral arches, spinous processes, etc.) are shown in gray, and the others are shown as white. Details of the image creation process shown in FIG. 5A will be described later.

  The spine is a vertebra 2 connected. The vertebra 2 has seven cervical vertebrae, twelve thoracic vertebrae, and five lumbar vertebrae connected from the head side. Each vertebra 2 includes a vertebral body 3, a vertebral foramen 4, a vertebral arch 5, a spinous process 6 and the like. The vertebral body 3 is a columnar portion located in front of the vertebra 2 (ventral side). The vertebral foramen 4 is a space located behind the vertebral body 3 when viewed from the front (ventral side) of the human body. When several vertebral bodies 3 are connected and the vertebral holes 4 overlap, a tube is formed. This tube is called the spinal canal, and the spinal cord and cauda equina pass through the spinal canal. The vertebral arch 5 is an arch-shaped portion located behind (back side) the vertebra 2. The vertebral body 3 has a simple shape, but the shape of the vertebral arch 5 is complicated. The vertebral arch 5 has an articulation surface with the other upper and lower vertebral bodies 3, and includes left and right upper joint processes, lower joint processes, lateral processes, and one spine process 6 extending rearward and downward. There are five joints between adjacent vertebral bodies 3 (four in vertebral arch 5 and one in vertebral body 3), and a joint 7 (vertebral joint) between vertebral bodies 3 has elastic disc 7 To do.

  The medical image processing apparatus 1 according to the present embodiment creates an image particularly suitable for interpretation of the vertebral body 3 and the vertebral hole 4 and the surrounding tissue. Hereinafter, an image mainly including the spine will be referred to as a “spine image”. The spine image includes a part or all of the vertebral body 3, vertebral hole 4, vertebral arch 5, spinous process 6, intervertebral disc 7, and the like described above.

  The first spine image creation process will be described with reference to FIGS. In the first spine image creation process, a plurality of tomographic images are processed, and reference points α, β, and γ are calculated for each tomographic image. The reference point is a point for defining a reference line or a reference plane that becomes a reference when creating a spine image.

  The processing of the CPU 11 of the medical image processing apparatus 1 described below includes processing for extracting regions such as the vertebral body 3, the vertebral foramen 4, the vertebral arch 5 and the spinous processes 6 in each tomographic image. In general, a part having a CT value similar to that of a bone, such as the vertebral body 3, vertebral arch 5 and spinous process 6, has a large difference in CT value from surrounding tissues, and thus can be easily extracted as a closed region. . Further, the vertebral foramen 4 can be extracted as a closed region if the entire periphery is surrounded by bones. On the other hand, the vertebral foramen 4 is difficult to extract as a closed region when a part of the periphery is surrounded by other than bone.

  As shown in FIG. 2, the CPU 11 of the medical image processing apparatus 1 determines the first image (tomographic image) (S1). Then, the CPU 11 calculates a straight line L that extends in the front-rear direction of the subject (the Y-axis direction in FIG. 3) and passes through the vertebral hole 4 (S2).

  In FIG. 3A, as an example of the straight line L, a straight line L1 (shown by a solid line) and a straight line L2 (shown by a dotted line) are illustrated. The straight line L1 is a straight line that passes through the center of the vertebra 2 (for example, the position of the center of gravity) and extends in the front-rear direction of the subject (the Y-axis direction in FIG. 3). The straight line L2 is a straight line that passes through the center of the region of the vertebral hole 4 (for example, the position of the center of gravity) and extends in the front-rear direction of the subject (the Y-axis direction in FIG. 3). In either case, the line extends in the front-rear direction of the subject (the Y-axis direction in FIG. 3) and passes through the vertebral foramen 4.

  Moreover, in FIG.3 (b), the straight line L3 (illustrated with a continuous line) is illustrated as an example of the straight line L. In FIG. The straight line L3 is the center of the portion (namely, the spinous process 6) pointed to the back (dorsal side) of the vertebral foramen 4 (for example, the position of the center of gravity of the spinous process 6 or the point located on the backmost side of the spinous process 6). The straight line extends in the front-rear direction (Y-axis direction in FIG. 3) of the subject. As long as the subject is not tilted left and right at the time of imaging, the straight line L3 also extends in the front-rear direction (Y-axis direction in FIG. 3) of the subject and becomes a straight line passing through the vertebral hole 4.

  In the image of FIG. 3A, the periphery of the vertebral foramen 4 is entirely surrounded by bones (white portions such as the vertebral body 3 and the vertebral arch 5), and the vertebral foramen 4 can be extracted as a closed region. . Therefore, it is possible to calculate the position of the center of gravity of the region of the vertebral foramen 4 and thus the straight line L2 described above can be calculated.

  On the other hand, in the image of FIG. 3B, a part of the periphery of the vertebral foramen 4 is surrounded by other than bone (gray to black part), and the vertebral foramen 4 cannot be extracted as a closed region. Therefore, it is impossible to calculate the position of the center of gravity of the region of the vertebral foramen 4 and consequently the straight line L2 described above cannot be calculated.

  Therefore, in the case of an image as shown in FIG. 3B, it is desirable to calculate the straight line L3. Since it is based on the spinous process 6 if it is the straight line L3, it can be calculated even when a part of the periphery of the vertebral foramen 4 is surrounded by other than bone (gray to black part).

  Next, the CPU 11 calculates Y coordinates Ya and Yb of the end points of the vertebral body 3 on the straight line L (S3). In FIG. 3A, the end point of the vertebral body 3 is illustrated by taking the straight line L1 as an example. Straight lines Y1a and Y1b indicate the Y-coordinate positions of the end points of the vertebral body 3. X1 is the X coordinate of the end point of the vertebral body 3. In FIG. 3B, the end point of the vertebral body 3 is illustrated by taking the straight line L3 as an example. Straight lines Y3a and Y3b indicate the Y-coordinate positions of the end points of the vertebral body 3. X3 is the X coordinate of the end point of the vertebral body 3.

  Next, the CPU 11 calculates a point α that divides the two end points of the vertebral body 3 on the ventral side on the straight line L (S4). Specifically, the CPU 11 sets the coordinates of the point α to α (X, Ya−Ca × W). Here, W is the distance between the two end points, and W = Yb−Ya. Ca is a positive constant (for example, 1.2). The value of Ca can be changed by the operator via the mouse 18 or the keyboard 19 as required. In this case, the operator may input a value corresponding to Ca × W instead of the value of Ca.

  Next, the CPU 11 calculates a point β that is located on the back side on the straight line L and that divides the distance between the two end points of the vertebral body 3 (S5). Specifically, the CPU 11 sets the coordinates of the point β to β (X, Yb + Cb × W). W is the same as in the case of α. Cb is also the same as Ca in the case of α, but may be a value different from Ca or the same value.

  FIG. 3A shows α and β taking the straight line L1 as an example. In the case of FIG. 3A, α (X1, Y1a−Ca × W1) and β (X1, Y1b + Cb × W1). In FIG. 3B, α and β are illustrated by taking the straight line L3 as an example. In the case of FIG. 3B, α (X3, Y3a−Ca × W3) and β (X3, Y3b + Cb × W3).

  Next, the CPU 11 calculates a midpoint γ of α and β (S6). In FIG. 3A, the straight line L1 is taken as an example to illustrate γ. In FIG. 3B, γ is illustrated by taking the straight line L3 as an example.

  Next, the CPU 11 checks whether all images have been determined, that is, whether α, β, and γ have been calculated for all images (S7).

  If all the images have not been determined (NO in S7), the CPU 11 determines the next image (S8) and repeats S2 to S7.

  When all images have been determined (YES in S7), the CPU 11 calculates the reference lines Lα passing through all α, the reference lines Lβ passing through all β, and the reference lines passing through all γ calculated for each tomographic image. Lγ is calculated (S9). Then, the CPU 11 creates a spine image using one of the reference lines Lα, Lβ, and Lγ in accordance with an instruction from the operator (S10). For example, the CPU 11 calculates any of the reference planes Pα, Pβ, and Pγ using any of the reference lines Lα, Lβ, and Lγ, and spine images based on one or more of the reference planes Pα, Pβ, and Pγ. Create

  As a spine image creation method, various known techniques such as a surface rendering method, a volume rendering method, a minimum value projection method, a maximum value projection method, a curved section reconstruction method, and a developed image creation method can be used. An example of a spine image creation method will be described later with reference to FIG.

  Next, the second spine image creation process will be described with reference to FIGS. 4 and 5. In the second spine image creation process, a CPR image is created based on a plurality of tomographic images, and a plurality of reference points α, β, γ, and δ are calculated from the CPR image. The definition of the reference point is the same as in the first spine image creation process.

  As shown in FIG. 4, the CPU 11 of the medical image processing apparatus 1 determines the first image (tomographic image) (S21). Then, the CPU 11 calculates a straight line L that extends in the front-rear direction of the subject (the Y-axis direction in FIG. 3) and passes through the vertebral hole 4 (S22). The process of S22 is the same as S2 of FIG.

  Next, the CPU 11 checks whether or not all images have been determined, that is, whether or not the straight line L has been calculated for all images (S23).

  When all the images have not been determined (NO in S23), the CPU 11 determines the next image (S24) and repeats S22 and S23.

  When all the images have been determined (YES in S23), the CPU 11 creates a CPR image composed of the straight line L group (S25). Then, the CPU 11 performs threshold processing on the CPR image and binarizes it (S26). The threshold value in the threshold processing is a CT value that can separate a bone (vertebral body 3, vertebral arch 5 and the like) and a portion other than the bone (including the vertebral hole 4 and the intervertebral disc 7 and the like). FIG. 5A shows a CPR image binarized in this way. Bone (vertebral body 3, vertebral arch 5 etc.) is gray, and parts other than bone (including vertebral foramen 4, intervertebral disc 7 etc.) are white.

  Next, the CPU 11 fills the gap in the body axis direction (slice direction) of the subject and leaves the longest to the second connected region (S27). Here, the gap is a portion other than the bone, and is a gray portion in FIG. For example, the CPU 11 scans the entire image with a pixel row (for example, 10) continuous in the slice direction as one unit, and the front row and the last row of the pixel row are gray and at least an intermediate pixel. If one is white, it is judged as a gap and turned gray. For example, when the number of pixel columns is 10, if (gray, gray, gray, gray, white, white, white, white, white, gray), the CPU 11 changes all white pixels to gray. Instead of changing all the white pixels to gray, a process of excluding the white pixels and compressing in the slice direction may be performed.

  When the process of filling the gap is performed, it is collected into several connected regions (regions in which gray pixels are connected). For these connected areas, the CPU 11 calculates the maximum length of the subject in the body axis direction (slice direction), leaves only the connected areas whose maximum length is up to the second, and changes the other connected areas to white. . One of the connection regions having the maximum lengths up to the first and second is a connection region of the vertebral body 3, and the other is a connection region of the vertebral arch 5 and the spinous process 6. The connection region on the ventral side is the connection region of the vertebral body 3, and the connection region on the dorsal side is the connection region of the vertebral arch 5 and the spinous process 6.

  Next, the CPU 11 calculates a center line (a center line passing through the centers of the plurality of vertebral bodies 3) along the longitudinal direction with respect to the connection region of the vertebral bodies 3 (S28). FIG. 5B shows a center line Lc (illustrated by a dotted line). For example, the CPU 11 sequentially calculates the center point in the Y-axis direction of the connection region of the vertebral body 3 at each position in the slice direction, and calculates the center line by connecting these center points. In addition, the CPU 11 may calculate the center line Lc using, for example, a known technique for calculating the core line of a luminal organ.

  Next, the CPU 11 calculates Y coordinates Ya (i) and Yb (i) of the end points of the vertebral body 3 on the straight line M (i) extending in the vertical direction of the center line Lc at each point i of the center line Lc. (S29), α (i), β (i), γ (i), and δ (i) are calculated based on Ya (i) and Yb (i) (S30).

  In S29 and S30, processing is performed for all points i on the center line Lc. The processing of Ya (i) and Yb (i) in S29 and the calculation processing of α (i), β (i), and γ (i) in S30 are the same as the processing of S3 to S6 in FIG.

  Further, the CPU 11 calculates an end point of the vertebral arch 5 on a straight line (= straight line M (i)) passing through the end point of the vertebral body 3 as δ (i).

  In the above description, instead of “straight line M (i) extending in the direction perpendicular to the center line Lc at each point i of the center line Lc”, “at each point i of the center line Lc in the Y-axis direction”. It is good also as the straight line M2 (i) to extend | stretch. This is because since the center line Lc is substantially parallel to the slice direction, the vertical direction of the center line Lc is also substantially parallel to the Y-axis direction. In the case of the straight line M2 (i), since it is not necessary to calculate the vertical direction of the center line Lc, the processing is easy.

  Further, in the case of the straight line M (i), when the coordinate in the slice direction of i <the coordinate in the slice direction of i + 1, the coordinate in the slice direction of β (i)> the coordinate in the slice direction of β (i). The position of the reference point in the slice direction may be switched. On the other hand, in the case of M2 (i), the position of the reference point in the slice direction is not interchanged, and subsequent processing becomes easy.

  In FIG. 5B, the straight line 30 is an example of the straight line M (i) described above. Ya and Yb are indicated by “●”, and α, β, and γ are indicated by “×”. The straight line 31 is an example of the straight line M2 (i) described above.

  Next, the CPU 11 passes through a reference line Lα that passes through all α (i), a reference line Lβ that passes through all β (i), a reference line Lγ that passes through all γ (i), and all δ (i). A reference line Lδ is calculated (S31). Then, the CPU 11 creates a spine image using any one of the reference lines Lα, Lβ, Lγ, and Lδ according to an instruction from the operator (S32). For example, the CPU 11 calculates any one of the reference planes Pα, Pβ, Pγ, Pδ using any one of the reference lines Lα, Lβ, Lγ, Lδ, and either one of the reference planes Pα, Pβ, Pγ, Pδ or Create spine images based on multiple.

  In FIG. 5B, reference lines Lα and Lβ (shown by solid lines) are shown. In order to improve readability, the reference lines Lγ and Lδ are not shown.

  As a spine image creation method, various known techniques such as a surface rendering method, a volume rendering method, a minimum value projection method, a maximum value projection method, a curved section reconstruction method, and a developed image creation method can be used. An example of a spine image creation method will be described later with reference to FIG.

  Next, a case where the minimum value projection method is used as an example of a spine image creation method will be described with reference to FIGS.

  FIG. 6 schematically shows a state in which the tomographic images 40 at the respective slice positions are stacked in the slice direction. The CPR image 41 is a CPR image composed of the straight line L group created in S25 of FIG. In FIG. 6, a binarized image subjected to threshold processing is shown in order to improve visibility. The CPR image 41 is not limited to the one created by the second spine image creation process, but is created based on the reference line calculated by the first spine image creation process or the second spine image creation process. It may be a thing.

The reference line Lβ is a reference line calculated by the first spine image creation process or the second spine image creation process. The reference plane Pβ is obtained by extending the reference line Lβ in the X-axis direction. That is, if the set of coordinates of each point of the reference line Lβ is {(X ^* , Y1, Z1),..., (X ^* , Yn, Zn)}, the CPU 11 ^* = Substitute X1,..., Xn (sampling points in the X-axis direction), {(X1, Y1, Z1),..., (X1, Yn, Zn),. Y1, Z1),..., (Xn, Yn, Zn)} is a set of coordinates of each point on the reference plane Pβ.

  Then, the CPU 11 emits a projection line from each point of the reference plane Pβ in the vertical direction of each point by the minimum value projection method, and projects the minimum value on the projection line 42 onto the projection plane 42.

  FIG. 7 illustrates a case where an approximate projection plane 43 is used instead of the projection plane 42 of FIG. Since the projection plane 42 in FIG. 6 is substantially perpendicular to the Y axis, it is also preferable to use the projection plane 43 perpendicular to the Y axis for the purpose of shortening the computation time.

  FIG. 7 also schematically shows a state in which the tomographic images 40 at the respective slice positions are stacked in the slice direction, similarly to FIG. The CPR image 41 is a CPR image composed of the straight line L group created in S25 of FIG. FIG. 7 also shows a binarized image subjected to threshold processing in order to improve visibility.

  The reference lines Lα and Lβ are reference lines calculated by the first spine image creation process or the second spine image creation process. The reference planes Pα and Pβ are obtained by extending the reference lines Lα and Lβ in the X-axis direction.

  Then, the CPU 11 emits a projection line in the Y-axis direction from each point of the reference plane Pβ toward the reference plane Pα by the minimum value projection method, and on the projection plane 43 between the reference plane Pα and the reference plane Pβ. Projects the minimum value on the projected projection line. In this case, a spine image focusing on the vertebral body 3 and the tissues before and after the vertebral body 3 (including the vertebral hole 4) is obtained.

  FIG. 8 shows a spine image created by the creation process shown in FIG. That is, the spine image shown in FIG. 8 is a minimum value projection image in the forward direction (abdominal side) from Pβ. In particular, a projection line is emitted from the reference plane Pβ, and the minimum value on the projection line to the reference plane Pα is obtained. It is the calculation result projected on the projection plane 43.

  The inside of the circle 60 is the region of the vertebral foramen for a normal subject and should be displayed as gray. However, a white area (high density area) exists inside the circle 60 and is considered an abnormal candidate.

  FIG. 9 is a cross-sectional image including the abnormality candidate region of FIG. 8 and orthogonal to the reference plane. The inside of the ellipse 61 is a region of the vertebral foramen for a normal subject and should be displayed as gray. However, a white area (high density area) exists inside the ellipse 60 and is considered an abnormal candidate.

  As shown in FIG. 8 and FIG. 9, the spine image created based on the reference line or reference plane calculated by FIG. 2 or FIG. 4 is used to interpret the spine (particularly the vertebral body 3 and the vertebral foramen 4). It is a suitable image.

  Next, a case where a developed image creation method is used as an example of a spine image creation method will be described with reference to FIGS. Since the developed image creation method itself is a known method, detailed description thereof is omitted. In the embodiment of the present invention, the minimum value projection is performed over the entire circumference of the reference line calculated by the first spine image creation process or the second spine image creation process, and a developed image is created.

  FIG. 10 also schematically shows a state in which tomographic images 40 at the respective slice positions are stacked in the slice direction, similarly to FIGS. 6 and 7. The CPR image 41 is a CPR image composed of the straight line L group created in S25 of FIG. Note that FIG. 10 also shows a binarized image subjected to threshold processing in order to improve visibility. The reference line Lβ is a reference line calculated by the first spine image creation process or the second spine image creation process.

  Then, the CPU 11 projects the minimum value on the moving radius 45 perpendicular to the reference line Lβ onto the cylindrical projection surface 44 over the entire periphery (θ = 0 to 360 degrees) of the reference line Lβ by the minimum value projection method. . The calculation result projected onto the projection surface 44 is developed on a plane and becomes a developed image.

  FIG. 11 illustrates a case where an approximate projection plane 46 is used instead of the projection plane 44 of FIG. Since the projection plane 44 in FIG. 10 is substantially parallel to the slice axis as a whole, it is also preferable to use a cylindrical projection plane 46 parallel to the slice axis for the purpose of shortening the calculation time.

  FIG. 11 also schematically shows a state in which tomographic images 40 at respective slice positions are stacked in the slice direction, as in FIG. The CPR image 41 is a CPR image composed of the straight line L group created in S25 of FIG. Note that FIG. 11 also shows a binarized image subjected to threshold processing in order to improve visibility. The reference line Lβ is a reference line calculated by the first spine image creation process or the second spine image creation process.

  Then, the CPU 11 projects the minimum value on the moving radius 47 orthogonal to the slice axis onto the cylindrical projection surface 46 over the entire periphery (θ = 0 to 360 degrees) of the reference line Lβ by the minimum value projection method. The calculation result projected on the projection surface 46 is developed on a plane and becomes a developed image.

  FIG. 12 shows a developed image of the spine created by the creation process shown in FIG. In the case of a developed image, interpretation can be performed over a wider range than the spine image shown in FIG. On the other hand, the spine image shown in FIG. 8 has the merit that it is easy to grasp the site and tissue.

  Next, a user interface for displaying the reference line automatically calculated by the CPU 11 and correcting the displayed reference line will be described with reference to FIGS.

  FIG. 13 shows an example of the main screen of the user interface. In FIG. 13, an image display area 51, an image display area 52, a reference position designation radio button 53, a line of sight designation radio button 54, an image creation method designation radio button 55, a parallel movement amount designation slide bar 56, and the like are illustrated. .

  In the image display area 51, the reference lines Lα, Lβ, Lγ, and Lδ are superimposed and displayed on the cross-sectional image of the spine having the midline as a cross section.

  The reference position designation radio button 53 is a radio button for designating the reference position of the spine image displayed in the image display area 52. In the example of FIG. 13, the reference position is designated as “β”. When the reference position is “β”, the CPU 11 creates a spine image with reference to the reference line Lβ or the reference plane Pβ. The same applies when the reference positions are “α”, “γ”, and “δ”.

  The line of sight designation radio button 54 is a radio button for designating the line of sight of the spine image displayed in the image display area 52. In the example of FIG. 13, the line of sight is designated as “rear”. When the line of sight is “rear”, the CPU 11 emits a projection line from the reference line or the reference plane toward the rear (back side) to create a spine image. When the line of sight is “front”, the CPU 11 emits a projection line from the reference line or reference plane toward the front (ventral side), and creates a spine image.

  The image creation technique designation radio button 55 is a radio button for designating a technique for creating a spine image displayed in the image display area 52. In the example of FIG. 13, the creation method is designated as “surface 3D”. When the creation method is “surface 3D”, the CPU 11 creates a spine image in which the surface of the object is three-dimensionally displayed by the surface rendering method. When the creation method is “Vol. Ren 3D”, the CPU 11 creates a spine image in which the surface shape and the inner surface shape of the object are three-dimensionally displayed by the volume rendering method. When the creation method is “maximum value projection”, the CPU 11 creates a spine image in which the maximum CT value in the projection path is projected onto the projection plane by the maximum value projection method. When the creation method is “minimum value projection”, the CPU 11 creates a spine image in which the minimum CT value in the projection path is projected onto the projection plane by the minimum value projection method.

  In the image display area 52, the designated reference position, line of sight, and spine image created by the image creation technique are displayed. In the example of FIG. 13, as designated by each radio button, the CPU 11 emits a projection line from the reference plane Pβ toward the rear (back side), creates a spine image by the surface rendering method, and displays it in the image display area 52. it's shown.

  The parallel movement amount designation slide bar 56 is a slide bar for designating the parallel movement amount of the reference line. When the user slides the position of the parallel movement amount designation slide bar 56 via the mouse 18 or the like, the CPU 11 receives an input of the parallel line movement amount of the reference line according to the movement amount, and receives the received parallel movement. The position of the reference line is translated and displayed according to the amount of movement. In the example of FIG. 13, when the user slides the position of the parallel movement amount designation slide bar 56, the CPU 11 displays the reference lines Lα, Lβ, Lγ, Lδ displayed in the image display area 51 of the subject. Translated and displayed in the front-rear direction. Further, the CPU 11 recreates and displays the spine image displayed in the image display area 52 according to the movement of the reference lines Lα, Lβ, Lγ, and Lδ.

  FIG. 14 is an enlarged view of a cross-sectional image displayed in the image display area 51. As will be described later, the CPU 11 accepts an input of the shape change amount of the reference line selected by the user, changes the shape of the selected reference line according to the shape change amount, and shapes other reference lines. Also change it. Therefore, for the purpose of making it easy for the user to identify the reference line, the CPU 11 extends the reference line to the outside of the cross-sectional image and displays it as indicated by a rectangle 71. Since only the reference line is displayed outside the cross-sectional image and is easily visible, the user can easily identify the reference line.

  FIG. 15 is an enlarged view of a cross-sectional image when the calculation result of the reference line is not correct. It can be seen that the lower portions of the reference lines Lα, Lβ, and Lγ meander to the left and are in an abnormal shape. In such a case, the user gives an instruction to change the position of the reference line in a screen example to be described later.

  16 and 17 are diagrams illustrating the first reference line correction process. First, on the screen of FIG. 16, the user presses a button indicating a reference line to be corrected and a correction button from among the reference lines Lα to Lδ, drags a part of the displayed reference line, and selects a desired position. Move to. In the example of FIG. 16, the button indicating the reference line Lβ and the correction button are pressed.

  In FIG. 17, the position of the reference line Lβ is changed compared to FIG. The CPU 11 subtracts the original coordinates from the coordinates of the changed reference line Lβ and stores them in the main memory 12 as the shape change amount of the reference line Lβ.

  Next, in the screen of FIG. 17, the user checks a check box indicating a reference line to be corrected together from the reference lines Lα to Lδ (excluding the corrected reference line), and the correction button Press. In the example of FIG. 1, the check boxes indicating the reference lines α and γ are checked, and the correction button is pressed.

  In contrast, the CPU 11 moves the position of the checked reference line in the same manner as the corrected reference line. More specifically, the CPU 11 moves the position of the checked reference line using the shape change amount of the reference line Lβ stored in the main memory 12. Accordingly, the user can easily instruct the shape change amount with respect to the first reference line as the shape change amount with respect to another reference line, which is convenient.

  FIG. 18 is a diagram for explaining the second reference line correction process. In the first reference line correction process, the operation representative reference line and the reference line to be similarly corrected are selected on different screens. However, in the second reference line correction process, both are displayed on the same screen. The screen configuration to be selected at.

  In the screen of FIG. 18, the user checks a check box indicating a reference line to be corrected from among the reference lines Lα to Lδ, presses a button indicating a reference line of the operation representative, presses a correction button, and displays the operation representative. Drag a part of the reference line to move to a desired position. In the example of FIG. 18, “α”, “γ”, and “β” are checked as reference lines to be corrected, the button indicating the reference line Lβ is pressed as the reference line for the operation representative, and the correction button is pressed.

  In the state of FIG. 18, when the user drags a part of the reference line of the operation representative and moves to a desired position, the CPU 11 subtracts the original coordinates from the coordinates of the changed reference line Lβ, and the reference line Stored in the main memory 12 as the shape change amount of Lβ. Further, the CPU 11 moves the position of the checked reference line using the shape change amount of the reference line Lβ stored in the main memory 12. The CPU 11 may move other reference lines to be corrected simultaneously following the movement of the operation representative reference line. Accordingly, the user can easily instruct the shape change amount with respect to a plurality of reference lines, which is convenient.

  As described above, the medical image processing apparatus 1 according to the embodiment of the present invention can automatically create and display an image suitable for interpreting the spine (particularly the vertebral body 3 and the vertebral hole 4).

  The above-described reference lines Lα and Lβ are curves defined by a set of points α and β that divide the two end points of the vertebral body 3, respectively. For example, as shown in FIG. 14, the reference lines Lα and Lβ are curves extending so as to sandwich each vertebral body 3 along the spine. By creating a spine image based on such reference lines Lα and Lβ, it is possible to create an image suitable for interpreting each vertebral body 3, each vertebral hole 4, and surrounding tissue.

  The reference line Lγ described above is a curve defined by a set of midpoints γ of points α and β that divide the distance between the two end points of the vertebral body 3. For example, as shown in FIG. 14, the reference line Lγ is a curved line extending along the spine so as to pass through the center line of the spine. By creating a spine image based on such a reference line Lγ, an image suitable for interpreting each vertebral body 3 and its surrounding tissue can be created.

  The reference line Lδ described above calculates the end point of the vertebral arch 5 on a straight line passing through the end point of the vertebral body 3. For example, as shown in FIG. 14, the reference line Lδ is a curve extending along the boundary between the vertebral hole 4 and the vertebral arch 5. By creating a spine image based on such a reference line Lγ, it is possible to create an image suitable for interpreting each vertebral hole 4 and the surrounding tissue.

  The preferred embodiments of the medical image processing apparatus and the like according to the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea disclosed in the present application, and these naturally belong to the technical scope of the present invention. Understood.

DESCRIPTION OF SYMBOLS 1 ......... Medical image processing apparatus 2 ......... vertebra 3 ......... vertebral body 4 ......... vertebral hole 5 ......... vertebral arch 6 ......... spinous process 7 ......... intervertebral disc

Claims (11)

A medical image processing apparatus for creating a spine image from a plurality of tomographic images,
Means for calculating a first straight line extending in the front-rear direction of the subject and passing through the vertebral fora in a single tomogram;
Means for calculating a first end point and a second end point of the vertebral body on the first straight line;
Means for calculating a reference point based on the first endpoint and the second endpoint;
Means for calculating the reference point in a plurality of tomographic images and calculating a reference line passing through all the reference points;
Means for creating the spine image using the reference line;
A medical image processing apparatus comprising: A medical image processing apparatus for creating a spine image from a plurality of tomographic images,
Means for calculating a first straight line extending in the front-rear direction of the subject and passing through the vertebral fora in a plurality of tomographic images;
Means for calculating a center line passing through the centers of a plurality of vertebral bodies in a curved cross-section reconstructed image comprising a plurality of pixels of the first straight line group;
Means for calculating a second straight line extending in the direction perpendicular to the center line or the front-rear direction of the subject at each point of the center line;
Means for calculating a first end point and a second end point of the vertebral body on the second straight line;
Means for calculating a reference point based on the first endpoint and the second endpoint;
Means for calculating the reference point in a plurality of tomographic images and calculating a reference line passing through all the reference points;
Means for creating the spine image using the reference line;
A medical image processing apparatus comprising: The medical image processing apparatus according to claim 1, wherein a straight line extending through the center of the spinous process and extending in the front-rear direction of the subject is calculated as the first straight line. 4. The medical image processing apparatus according to claim 1, wherein a point that divides an area between the first end point and the second end point is calculated as the reference point. 5. Unlike the first point, the first point that divides between the first end point and the second end point is different from the first point, and the first point that divides between the first end point and the second end point is used as the reference point. The medical image processing apparatus according to claim 1, wherein a midpoint between the two points is calculated. The medical image processing apparatus according to claim 1, wherein an end point of a vertebral arch on a straight line passing through the first end point and the second end point is calculated as the reference point. Means for creating a cross-sectional image composed of a plurality of pixels of the first straight line group;
Means for overlaying and displaying the reference line on the cross-sectional image;
Means for accepting an input of a translation amount of the reference line and translating and displaying the position of the reference line according to the translation amount;
The medical image processing apparatus according to claim 1, further comprising: In the case where a plurality of the reference lines are calculated and displayed on the cross-sectional image,
Accepting the input of the shape change amount of the selected reference line, changing the shape of the selected reference line according to the shape change amount, and changing the shape of the other reference line together The medical image processing apparatus according to claim 7. The medical image processing apparatus according to claim 8, wherein the reference line is extended and displayed outside the cross-sectional image. A medical image processing method for creating a spine image from a plurality of tomographic images,
In a single tomographic image, extending in the front-rear direction of the subject and calculating a first straight line passing through the vertebral foramen;
Calculating a first end point and a second end point of the vertebral body on the first straight line;
Calculating a reference point based on the first endpoint and the second endpoint;
Calculating the reference point in a plurality of tomographic images and calculating a reference line passing through all the reference points;
Creating the spine image using the reference line;
A medical image processing method comprising: A medical image processing method for creating a spine image from a plurality of tomographic images,
In a plurality of tomographic images, extending in the front-rear direction of the subject and calculating a first straight line passing through the vertebral foramen;
Calculating a center line passing through the centers of a plurality of vertebral bodies in a curved cross-section reconstruction image composed of a plurality of pixels of the first straight line group;
Calculating a second straight line extending in the direction perpendicular to the center line or the front-rear direction of the subject at each point of the center line;
Calculating a first end point and a second end point of the vertebral body on the second straight line;
Calculating a reference point based on the first endpoint and the second endpoint;
Calculating the reference point in a plurality of tomographic images and calculating a reference line passing through all the reference points;
Creating the spine image using the reference line;
A medical image processing method comprising: