JP6403136B2 - Medical image processing apparatus, medical image analysis system, medical image processing method and program - Google Patents

Description

  The present invention relates to a medical image processing apparatus, a medical image analysis system, a medical image processing method, and a program.

  Osteoporosis is a symptom in which small holes occur frequently in the bone because the bone resorption rate is higher than the bone formation rate. As the population ages, the number of patients suffering from osteoporosis is increasing. Then, development of the medicine used for the treatment of osteoporosis has become active (for example, refer patent documents 1 and 2).

International Publication No. 2011/030774 Special table 2010-506844

  Osteoporosis causes fractures of the spinal vertebral body and the like. The aforementioned drugs are also used to treat such osteoporotic vertebral body fractures. Treatment of vertebral fractures is long. In order to confirm the healing state of the fractured vertebral body, when it was considered that bone fusion had been obtained, dynamic imaging was performed, and by confirming that the instability of the vertebral body had disappeared by the imaging, It is determined whether or not fusion has been obtained.

  On the other hand, for the measurement of bone density, a DEXA (Dual-Energy X-ray Absorptiometry) method using X-rays is generally used. If the DEXA method is used, the bone density can be easily measured for each vertebral body. However, in the DEXA method, it can be confirmed that the numerical value of the bone density has improved, but it cannot be known how much the bone mass has increased in which part of the cancellous bone or cortical bone of the vertebral body.

  In addition to these examinations, imaging of three-dimensional X-ray CT images inside the vertebral body is also widely performed by computed tomography (CT). If the CT image of the sagittal cross section, the CT image of the horizontal cross section, and the CT image of the coronal cross section are observed over time, the process of bone fusion can be confirmed to some extent. However, since the CT image is displayed in 256 gray levels (black and white display), it is difficult to visually discriminate minute bone mass changes in the vertebral body. If the structure inside the vertebral body is highlighted to see the process of bone fusion, the image of the surrounding part is lost and the positional relationship between the vertebral body and the surrounding part cannot be grasped. It becomes difficult to make use for treatment.

  The present invention has been made to solve the above-described problems, and is a medical image processing apparatus, a medical image analysis system, and a medical image processing for generating an image for appropriately diagnosing the internal state of a vertebral body. An object is to provide a method and a program.

In order to achieve the above object, a medical image processing apparatus according to the first aspect of the present invention provides:
An image reconstruction unit configured to represent a CT value in gray scale and reconstruct a first CT image of a two-dimensional section including a vertebral body based on three-dimensional image data of a region including a vertebra obtained by computed tomography;
CT for performing color mapping on the first CT image in which the CT value of the cancellous bone region in the reconstructed first CT image is the minimum value and the CT value of the cortical bone region is the maximum value A range setting section for setting a range of values;
Based on the CT value range set by the range setting unit, the first CT image is subjected to color mapping using a plurality of colors with color coding according to the CT value of the range . A color image generation unit that converts the CT image of 1 into a second CT image that represents a CT value in color;
A fusion image generating unit that generates a fusion image by superimposing the first CT image and the second CT image;
Is provided.

The image reconstruction unit
Reconstructing the first CT image in the same cross section at the plurality of different time points from each of the three-dimensional image data obtained by computer tomography at a plurality of different time points,
The range setting unit
Based on a CT value of the cancellous bone region and a CT value of the cortical bone region in the first CT image at the reference time point among the plurality of different time points, Set the range,
The color image generation unit
Each of the first CT images in the same cross section at a plurality of different time points is converted into a second CT image in which CT values are expressed in color by performing color mapping in the range set by the range setting unit. And
The fusion image generation unit
The first CT image and the second CT image at the same time point are overlapped to generate the fusion images at a plurality of different time points, respectively.
It is good as well.

A display output unit for comparing and displaying the fusion image of the same cross section at a plurality of different time points,
It is good as well.

The range setting unit includes:
The average CT value of the cancellous bone region is the minimum CT value for color mapping,
The average value of CT values of the cortical bone region is set as a maximum value of CT values for performing color mapping, and a range of CT values for performing color mapping is set.
It is good as well.

The image reconstruction unit
Reconstructing a plurality of different horizontal cross-sectional CT images of the vertebral body as the first CT image;
It is good as well.

The range setting unit includes:
Calculate the average value of the center of the vertebral body of the first CT image and the five points on the front, back, left and right as the average value of the CT value of cancellous bone,
Calculate the average value of three cortical bones including vertebral arches and pedicles as the average CT value of cortical bone.
It is good as well.

A medical image analysis system according to a second aspect of the present invention provides:
A medical image processing apparatus of the present invention;
An imaging device for imaging a medical image processed by the medical image processing device;
Is provided.

A medical image processing method according to a third aspect of the present invention provides:
An image for reconstructing a first CT image of a two-dimensional cross section including a vertebral body by expressing a CT value in gray scale based on three-dimensional image data of a region including a vertebra obtained by computer tomography using a computer A reconfiguration step;
Using the computer, for the first CT image, the CT value of the cancellous bone region in the reconstructed first CT image is the minimum value, and the CT value of the cortical bone region is the maximum value . A range setting step for setting a range of CT values for performing color mapping;
Using a computer, based on the CT value range set in the range setting step, color mapping using a plurality of colors is performed on the first CT image with color coding according to the CT value in the range. A color image generating step of converting the first CT image into a second CT image representing a CT value in color;
Using a computer, a fusion image generating step of generating a fusion image by superimposing the first CT image and the second CT image;
including.

In the image reconstruction step,
Reconstructing the first CT image in the same cross section at the plurality of different time points from each of the three-dimensional image data obtained by computer tomography at a plurality of different time points,
In the range setting step,
Based on a CT value of the cancellous bone region and a CT value of the cortical bone region in the first CT image at the reference time point among the plurality of different time points, Set the range,
In the color image generation step,
Each of the first CT images in the same cross section at a plurality of different time points is converted into a second CT image in which CT values are expressed in color by performing color mapping in the range set by the range setting unit. And
In the fusion image generation step,
The first CT image and the second CT image at the same time point are overlapped to generate the fusion images at a plurality of different time points, respectively.
It is good as well.

A program according to the fourth aspect of the present invention is:
Computer
An image reconstruction unit that represents CT values in gray scale and reconstructs a first CT image of a two-dimensional section including a vertebral body based on three-dimensional image data of a region including a vertebra obtained by computed tomography;
CT for performing color mapping on the first CT image in which the CT value of the cancellous bone region in the reconstructed first CT image is the minimum value and the CT value of the cortical bone region is the maximum value A range setting section for setting the range of values,
Based on the CT value range set by the range setting unit, the first CT image is subjected to color mapping using a plurality of colors with color coding according to the CT value of the range . A color image generation unit that converts one CT image into a second CT image in which CT values are expressed in color;
A fusion image generating unit that generates a fusion image by superimposing the first CT image and the second CT image;
To function as.

The image reconstruction unit
Reconstructing the first CT image in the same cross section at the plurality of different time points from each of the three-dimensional image data obtained by computer tomography at a plurality of different time points,
The range setting unit includes:
Based on a CT value of the cancellous bone region and a CT value of the cortical bone region in the first CT image at the reference time point among the plurality of different time points, Set the range,
The color image generation unit
Each of the first CT images in the same cross section at a plurality of different time points is converted into a second CT image in which CT values are expressed in color by performing color mapping in the range set by the range setting unit. And
The fusion image generation unit
The first CT image and the second CT image at the same time point are overlapped to generate the fusion images at a plurality of different time points, respectively.
To make the computer work,
It is good as well.

  According to the present invention, a fusion image is generated by superimposing a grayscale image that displays a region around a vertebral body with good contrast and a color image that displays the internal state of the vertebral body with color emphasis. This fusion image is an image that emphasizes the internal state of the vertebral body without erasing the image of the region around the vertebral body. For this reason, the internal state of the vertebral body can be appropriately diagnosed by looking at this fusion image.

It is a block diagram which shows the structure of the medical image analysis system which concerns on embodiment of this invention. It is a block diagram which shows the hardware constitutions of the medical image processing apparatus of FIG. It is a figure which shows an example of the three-dimensional image data of the area | region containing a vertebra. It is a figure which shows an example of the display image of a sagittal section, a horizontal section, and a coronal section. It is a figure which shows a mode that the horizontal cross section of a vertebral body upper part, a vertebral body middle part, and a vertebral body lower part is set. It is a figure which shows an example of the two-dimensional cross-sectional image of a gray scale. It is a figure which shows an example of the color mapping with respect to gray scale image data. (A) And (B) is a figure which shows an example of the area | region of cancellous bone and cortical bone. (A) is a figure showing an example of a gray scale image. (B) is a diagram showing an example of a color image. (C) is a figure which shows an example of a fusion image. It is a figure which shows the flow of conversion from a gray scale image to a color image. It is a figure which shows an example of the comparison display of the fusion image (horizontal cross section) in a several different time. It is a flowchart of a diagnostic process. It is a flowchart of an image reconstruction process. It is a flowchart of a window setting process. It is a figure which shows an example of the comparative display of the fusion image (sagittal section) of a several different time. It is a figure which shows a different window for every subject.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  A medical image analysis system 100 according to this embodiment shown in FIG. 1 is used for, for example, treatment of a vertebral fracture caused by osteoporosis. The vertebral body is a part of the vertebra. A vertebra is an individual bone that forms a segment of the spine. The vertebrae are arranged in a line.

  As shown in FIG. 1, the medical image analysis system 100 includes an imaging device 1 and a medical image processing device 2. The imaging device 1 and the medical image processing device 2 are connected via a communication network. Through this communication network, data can be transmitted and received between the imaging apparatus 1 and the medical image processing apparatus 2.

  The imaging apparatus 1 is an apparatus (modality) that captures an X-ray CT image by computed tomography (CT). The imaging device 1 captures three-dimensional image data including a subject's spine (vertebra). The imaging device 1 includes an X-ray tube and a detector. X-rays emitted from the X-ray tube are incident on the subject, partially absorbed in the body, attenuated, and transmitted, reach a detector located on the opposite side of the X-ray tube, and are detected. During this time, since the X-ray tube and the detector rotate around the subject, the detection result when the subject receives X-rays from all directions is detected by the detector. The detection result of the detector is stored in the imaging device 1 as raw data.

  Furthermore, the imaging device 1 generates cross-sectional data (slice image data) of the upper body of the subject by performing image reconstruction processing (such as inverse radon transformation) based on the stored raw data. Furthermore, the imaging device 1 generates three-dimensional image data of the upper body of the subject based on the slice image data. In this way, three-dimensional image data including vertebrae is obtained. The obtained three-dimensional image data is transmitted as DICOM (Digital Imaging and Communications in Medicine) data to the medical image processing apparatus 2 via the communication network.

  DICOM data refers to data generated based on the DICOM standard. The DICOM standard is mainly used as a format for medical image data. The DICOM data is composed of the three-dimensional image data and incidental information according to the DICOM standard. The incidental information is attribute information of image data such as patient information, imaging condition information, image information, and display information, and is embedded as tag information in DICOM data.

  The medical image processing apparatus 2 generates a two-dimensional cross-sectional image for diagnosing the internal state of the vertebral body based on the three-dimensional image data including the vertebrae included in the received DICOM data.

  FIG. 2 shows a hardware configuration of the medical image processing apparatus 2 of FIG. As illustrated in FIG. 2, the medical image processing apparatus 2 includes a control unit 31, a main storage unit 32, an external storage unit 33, an operation unit 34, a display unit 35, and a communication unit 36. The main storage unit 32, the external storage unit 33, the operation unit 34, the display unit 35, and the communication unit 36 are all connected to the control unit 31 via the internal bus 30.

  The control unit 31 includes a CPU (Central Processing Unit) and the like. The CPU executes the program 39 stored in the external storage unit 33, thereby realizing each component of the medical image processing apparatus 2 shown in FIG.

  The main storage unit 32 is composed of a RAM (Random-Access Memory) or the like. The main storage unit 32 is loaded with a program 39 stored in the external storage unit 33. In addition, the main storage unit 32 is used as a work area (temporary data storage area) of the control unit 31.

  The external storage unit 33 includes a nonvolatile memory such as a flash memory, a hard disk, a DVD-RAM (Digital Versatile Disc Random-Access Memory), and a DVD-RW (Digital Versatile Disc ReWritable). In the external storage unit 33, a program 39 to be executed by the control unit 31 is stored in advance. Further, the external storage unit 33 supplies data used when executing the program 39 to the control unit 31 in accordance with an instruction from the control unit 31, and stores the data supplied from the control unit 31.

  The operation unit 34 includes a pointing device such as a keyboard and a mouse, and an interface device that connects the keyboard and the pointing device to the internal bus 30. Information regarding the content operated by the operator is input to the control unit 31 via the operation unit 34.

  The display unit 35 is configured by a CRT (Cathode Ray Tube) or an LCD (Liquid Crystal Display). The display unit 35 displays 3D image data including vertebrae, 2D cross-sectional images of vertebral bodies, and the like.

  The communication unit 36 includes a serial interface or a parallel interface. The communication unit 36 is connected to the imaging device 1 via a communication network and receives DICOM data sent from the imaging device 1.

  1 includes a control unit 31, a main storage unit 32, an external storage unit 33, an operation unit 34, a display unit 35, a communication unit 36, and the like. The various components of the medical image processing apparatus 2 illustrated in FIG. The function is exhibited by being executed as a hardware resource.

  As shown in FIG. 1, the medical image processing apparatus 2 having the hardware configuration shown in FIG. 2 has a storage unit 10, a data acquisition unit 11, an image reconstruction unit 12, and a window setting. Unit 13, color image generation unit 14, fusion image generation unit 15, and display output unit 16.

  The storage unit 10 stores various data. One of the data stored by the storage unit 10 is DICOM data 21. The memory | storage part 10 respond | corresponds to the external memory | storage part 33 of FIG. 2 among the hardware constitutions shown in FIG.

  The data acquisition unit 11 corresponds to the control unit 31, the operation unit 34, the display unit 35, and the communication unit 36 in the hardware configuration illustrated in FIG. The data acquisition unit 11 acquires DICOM data transmitted from the imaging device 1.

  More specifically, when the control unit 31 as the data acquisition unit 11 executes the program 39, a data acquisition button for acquiring data from the imaging device 1 is displayed on the display unit 35. When the data acquisition button is selected by an operation input of the operation unit 34, the control unit 31 transmits a data acquisition command to the imaging apparatus 1 via the communication unit 36. Upon receiving this command, the imaging apparatus 1 transmits DICOM data to the communication unit 36. The control unit 31 receives the DICOM data received via the communication unit 36. The control unit 31 stores the received DICOM data in the storage unit 10 as the DICOM data 21.

  In the imaging apparatus 1, a plurality of subjects are imaged, and each imaging data is obtained as DICOM data. Even for the same subject, imaging is performed at a later date. For example, the same subject is imaged at intervals such as immediately after a fracture, 4 weeks later, 12 weeks later, and DICOM data is generated. The data acquisition unit 11 receives the plurality of DICOM data and stores them in the storage unit 10 as DICOM data 21. The DICOM data 21 is an aggregate of such three-dimensional image data.

  The image reconstruction unit 12 corresponds to the control unit 31, the operation unit 34, and the display unit 35 in the hardware configuration illustrated in FIG. The image reconstruction unit 12 inputs 3D image data of a region including a vertebra to be diagnosed from the DICOM data 21 stored in the storage unit 10. FIG. 3 shows an example of the three-dimensional image data. As shown in FIG. 3, this three-dimensional image data is three-dimensional image data in which the inside of the subject is expressed by CT values.

  The CT value is also referred to as a HU (Hounsfield unit) value, and the higher the CT value, the higher the value (the harder it is to transmit X-rays). The unit of CT value is HU, air is -1000HU, water is 0HU, and the hardest bone is 1000HU. Therefore, in this three-dimensional image data, the firmer bone has a higher CT value and a weak bone has a lower CT value. The CT value of bone also changes depending on the fracture. In FIG. 3, illustrations other than the bone portion are omitted. In the actual image, images of other parts also appear.

  The image reconstruction unit 12 reconstructs a CT image (first CT image) of a two-dimensional section including a vertebral body based on the input three-dimensional image data. This CT image is a gray image expressing CT values in gray scale. The reconstructed gray image is stored in the storage unit 10 as grayscale CT image data 22.

  More specifically, the control unit 31 as the image reconstruction unit 12 executes the program 39 in response to an operation input from the operation unit 34, and displays the 3D image data included in the DICOM data 21 on the display unit 35. Display the list. When one three-dimensional image data is selected from the list displayed on the display unit 35 by an operation input from the operation unit 34, the control unit 31 activates a three-dimensional (3D) viewer included in the program 39. Then, the display unit 35 displays, for example, three-dimensional image data as shown in FIG. 3 by the 3D viewer.

  The program 39 also includes an MPR (arbitrary multi-section reconstruction) function program. The MPR function is a function for reconstructing and displaying image data of an arbitrary two-dimensional section from three-dimensional image data. The program 39 also includes a two-dimensional (2D) viewer. The display unit 35 also displays an MPR activation button together with the three-dimensional image data. When an activation button is selected by an operation input from the operation unit 34, the control unit 31 activates the MPR function and the 2D viewer. As shown in FIG. 4, the display unit 35 reconstructs and displays a sagittal cross-sectional image, a horizontal cross-sectional image, and a coronal cross-sectional image from the three-dimensional image data by the MPR function and the 2D viewer.

  The sagittal section, horizontal section and coronal section can be adjusted. The operator can change the position of the sagittal section by operating the operation unit 34 while viewing the sagittal section image, the horizontal section image, and the coronal section image displayed on the display unit 35. In response to this change, the control unit 31 reconstructs the changed sagittal cross-sectional image, horizontal cross-sectional image, and coronal cross-sectional image by the MPR function, and displays them on the display unit 35. By repeating the adjustment of the cross section by the operation input of the operation unit 34 and the display of the adjustment image of the display unit 35, the exact position of the sagittal cross section is determined.

  When the position of the sagittal section is determined by the operation input of the operation unit 34, the control unit 31 as the image reconstruction unit 12 uses the sagittal section as a reference to display an image of the horizontal section of the region including the vertebral body. Reconfigure. The image reconstruction unit 12 (control unit 31) stores the reconstructed horizontal slice image data as grayscale CT image data 22 in the storage unit 10.

  The image reconstruction unit 12 reconstructs CT images of three horizontal sections of the upper vertebral body, the middle vertebral body, and the lower vertebral body as grayscale images. FIG. 5 shows a state in which horizontal sections are designated at the upper vertebral body, the middle vertebral body, and the lower vertebral body. In FIG. 5, horizontal sections of the upper, middle, and lower vertebral bodies are selected with a thickness of 2 mm, an interval of 2 mm, and an effective visual field of 100 mm.

  FIG. 6 shows an example of this grayscale two-dimensional cross-sectional image. This image is an image of a horizontal section including vertebral bodies and other parts. This gray scale image is an image expressed by a CT value of 256 gradations. For example, among the above-described −1000 HU to +1000 HU, CT values in a range delimited by a predetermined window are allocated and displayed with 256 grayscale brightness values. As shown in FIG. 6, the vertebral body, which is a bone, has a lower X-ray transmittance than other parts, so the CT value is higher than the other parts and appears whitish.

  The vertebral body is formed by cancellous bone and cortical bone. The cancellous bone is a cancellous bone contained in the spinal vertebral body and the like. Cortical bone is bone that thinly covers cancellous bone or bone that has a thick bamboo tube shape like the central portion of long bone. Since cortical bone is harder and has a higher bone density than cancellous bone, in the CT image, the CT value is high in the cortical bone region, and the CT value is low in the cancellous bone region.

  The window setting unit 13 as the range setting unit corresponds to the control unit 31, the operation unit 34, and the display unit 35 in the hardware configuration illustrated in FIG. The window setting unit 13 applies the CT image of the grayscale two-dimensional image to the CT image of the cancellous bone region and the CT value of the cortical bone region included in the reconstructed grayscale CT image data 22. The CT value range (window) for color mapping is set. The window setting unit 13 inputs grayscale CT image data 22. The window setting unit 13 extracts the cancellous bone region, and calculates the average value of the CT values in the region as the minimum value of the CT values for color mapping. Further, the window setting unit 13 extracts a cortical bone region, and calculates an average value of CT values in the region as a maximum value of CT values for performing color mapping.

  The window setting unit 13 sets the width (WW) and level (WL) of the window for performing color mapping based on the calculated maximum CT value and minimum CT value. The level WL of the window is the median value of the window. The CT value range (WW, WL) for color mapping is stored in the storage unit 10 as window data 23. As the CT value increases, 256 colors from blue (cold color system) to red (warm color system) are given to the CT values in this window.

  FIG. 7 shows the relationship between the CT value of the grayscale image data and the window. As shown in FIG. 7, in the gray scale CT image data 22, the CT value takes a value of −1000 to +1000. As the CT value increases, the color of each pixel changes from black to white. Since the vertebral body region appears whiter than other regions, the average CT value of the cortical bone region and the average CT value of the cancellous bone region are higher than the CT values of the other regions. .

  Since the cortical bone region appears whiter than the cancellous bone region, the average CT value of the cortical bone region is higher than the average CT value of the cancellous bone region. Therefore, if the CT value range for color mapping is determined by setting the average CT value of the cortical bone region as the maximum value and the average CT value of the cancellous bone region as the minimum value, the grayscale CT image data 22 is obtained. Color mapping can be performed accurately on the bone area of the bone. As shown in FIG. 7, the window level WL is an intermediate value between the average CT value of the cortical bone region and the average CT value of the cancellous bone region, and the window width WW is the cortical bone region. The difference between the average CT value and the average CT value of the cancellous bone region.

  There are various methods for extracting the cancellous bone region and the cortical bone region. For example, by designating a part of the gray scale image displayed on the display unit 35 by an operation input of the operation unit 34, the cancellous bone and cortical bone regions are extracted, and the control unit 31 extracts the extracted regions. The average value of the CT values can be calculated.

  FIG. 8A shows five regions of cancellous bone ROI1 to ROI5 and three regions of cortical bone ROI6 to ROI8 respectively designated in the horizontal cross-sectional images at the upper vertebral body, middle vertebral body, and lower vertebral body. It is shown. As shown in FIG. 8B, the window setting unit 13 calculates the average value of the regions of interest ROI1 to ROI5 taken at the center of the vertebral body of each grayscale image and the five points on the front, back, left, and right, and the CT value of the cancellous bone. The average value of the regions of interest ROI6 to ROI8 captured by three cortical bones of the vertebra and pedicle is calculated as the average value of CT values of cortical bone. If there is a point that is difficult to specify among the points, the specification of that point may be omitted.

  The color image generation unit 14 corresponds to the control unit 31, the operation unit 34, and the display unit 35. The color image generation unit 14 performs gray mapping on the gray scale image based on the CT value range (window data 23) set by the window setting unit 13, thereby converting the gray scale CT image data 22 into CT. The value is converted into a color image (second CT image) representing the color. The color image is stored in the storage unit 10 as color image data 24.

  FIG. 9A shows an example of a gray scale image, and FIG. 9B shows an example of a color image generated by performing color mapping on the cross-sectional image. . In FIG. 9B, a pixel to which blue is given is dark and a pixel to which red is given is shown to be bright. In this color image, pixels that are not colored are shown in black, and only the bone region is colored and displayed. In the X-ray image, the CT value correlates with the X-ray transmittance of the region. Therefore, the CT value can be regarded as representing bone density in the bone region. In this color image, the inside of the bone area is colored with the color corresponding to the CT value of the inside area, and the distribution of the bone density in the area is determined by the color distribution in the bone area. Can be confirmed.

  This coloring is performed by an operation input from the operation unit 34 by the control unit 31 as the color image generation unit 14 and displaying the image on the display unit 35.

  The fusion image generation unit 15 corresponds to the control unit 31, the operation unit 34, and the display unit 35. The fusion image generation unit 15 aligns the grayscale CT image data 22 and the color image data 24 generated from the grayscale image, and superimposes them to generate a fusion image. The fusion image is stored in the storage unit 10 as fusion image data 25.

  FIG. 9C shows a fusion image generated by superimposing the gray image of FIG. 9A and the color image of FIG. 9B. Although shown in black and white in FIG. 9C, this fusion image is a mixed image of gray scale and color in which the bone region is displayed in color and the other parts are displayed in gray scale. .

  The display output unit 16 corresponds to the control unit 31 and the display unit 35 in the hardware configuration of FIG. The display output unit 16 inputs the fusion image data 25 and displays it. As shown in FIG. 9C, the fusion image is an image that clearly displays a portion other than the bone and emphasizes the structure inside the bone region with a color. This is because the bone region is color-mapped in a window independent from the black and white shaded portion window.

  As described above, the medical image analysis system 100 displays a fusion image that clearly displays a region other than a bone and emphasizes the internal state of the bone region with a color, and thus is useful for treatment of a vertebral fracture caused by osteoporosis. It is. For example, if both a fusion image at the time of injury of a vertebral body fracture and a fusion image after several months have been generated and displayed for comparison, the healing state of the vertebral body can be confirmed.

  In this case, the image reconstruction unit 12 reconstructs a grayscale image in the same cross section at a plurality of different time points from each of the three-dimensional image data obtained by the imaging device 1 at a plurality of different time points. FIG. 10 shows a gray image immediately after a vertebral fracture, which is a reference time reconstructed in this way, a gray image of the same cross section after 4 weeks, and a gray image of the same cross section after 12 weeks. Yes.

  The window setting unit 13 selects a CT value for performing color mapping based on the CT value of the cancellous bone region and the CT value of the cortical bone region in the grayscale image at a reference time point among a plurality of different time points. Set the range. FIG. 10 shows how the window width WW and window level WL are determined based on the gray image at the reference time (immediately after being damaged).

  The color image generation unit 14 converts each of the grayscale images in the same cross section at a plurality of different time points into a color image that expresses the CT value in color by performing color mapping within the range set by the window setting unit 13. To do. In FIG. 10, the gray image captured immediately after the vertebral fracture, which is the reference time, the gray image of the same cross section captured after 4 weeks, and the gray image of the same cross section captured after 12 weeks have the same window width WW, A state in which color mapping is performed according to the level WL is shown.

  The fusion image generating unit 15 generates a fusion image at a plurality of different time points by superimposing a gray image at the same time point and a color image of the same cross section.

  The display output unit 16 compares and displays the fusion image at the reference time and the fusion image at another time point. FIG. 11 shows a fusion image (Baseline axial image) at the base time (immediately after injury), a fusion image after 4 weeks (4week axial image), and a fusion image after 12 weeks (12week axial image). Yes. As shown in FIG. 11, compared to the reference time, after 4 weeks, the color of the pixel in the cancellous bone area has changed to a sparse but warm color system, and the bone density of the cancellous bone has increased. Recognize. In addition, after 12 weeks, the color of the pixel in the cancellous bone region has changed to a warmer color system, and the bone density of the cancellous bone has increased. In this way, if the fusion images at different times are compared and displayed, the temporal change in the bone can be visually confirmed.

  Next, the flow of diagnosis processing by the medical image analysis system 100 will be described with reference to the flowcharts of FIGS. Here, a description will be given of a case where a fusion image of a two-dimensional horizontal section is displayed comparatively at a reference time (immediately after an injury), 4 weeks after the reference time, and 12 weeks after the reference time.

  When the execution of the program 39 is instructed by the operation of the operation unit 34, the control unit 31 reads the program 39 stored in the external storage unit 33 into the main storage unit 32 and starts executing the processing shown in FIG. To do.

  As shown in FIG. 12, first, the data acquisition unit 11 performs DICOM data acquisition processing (step S1). Here, the data acquisition unit 11 receives the DICOM data from the imaging apparatus 1 and stores it in the storage unit 10 as the DICOM data 21. Here, it is assumed that DICOM data at the reference time (immediately after the injury), 4 weeks after the reference time, and 12 weeks after the reference time are obtained and stored in the storage unit 10.

  Subsequently, the image reconstruction unit 12 performs an image reconstruction process (step S2). FIG. 13 shows the flow of the image reconstruction process. As shown in FIG. 13, first, the image reconstruction unit 12 selects three-dimensional image data from the displayed list of DICOM data 21 (step S21). Here, the three-dimensional image data picked up by the image pickup apparatus 1 at the reference time (immediately after being damaged) is selected.

  When the 3D image data is selected, the image reconstruction unit 12 opens the 3D viewer and displays the 3D image data on the display unit 35 (step S22). Thereby, for example, a three-dimensional image as shown in FIG. 3 is displayed on the display unit 35. Here, when the MPR function is selected, the image reconstruction unit 12 displays a sagittal cross-sectional image, a horizontal cross-sectional image, and a coronal cross-sectional image as shown in FIG. 4 using the MPR function ( Step S23).

  The sagittal section displayed at the beginning is not accurate. Therefore, the image reconstruction unit 12 adjusts the sagittal section (step S24). Specifically, the control unit 31 as the image reconstruction unit 12 reconstructs the image of the position of the sagittal section adjusted according to the operation input of the operation unit 34 and displays the reconstructed image on the display unit 34. Let In this way, the sagittal section is adjusted. When the sagittal section is adjusted, the horizontal section and the coronal section are adjusted accordingly.

  After the adjustment, the MPR function causes the image reconstruction unit 12 to generate horizontal cross-section image data (upper vertebral body, middle vertebral body, lower vertebral body) for the fractured vertebral body (step S25). The horizontal sections of the upper vertebral body, middle vertebral body, and lower vertebral body can be arbitrarily set as shown in FIG. When crushing due to a fracture is significant, the horizontal section to be set may be one or two. Further, the image reconstruction unit 12 stores the horizontal slice image data (upper vertebral body, middle vertebral body, lower vertebral body) as grayscale image data 22 in the storage unit 10 (step S26).

  Returning to FIG. 12, the medical image processing apparatus 2 determines whether or not the three-dimensional image data at the reference time (immediately after the injury) is being processed (step S3). At this time, the three-dimensional image data at the reference time (immediately after being damaged) is processed. When it is determined that the three-dimensional image data at the reference time (immediately after being damaged) is being processed (step S3; Yes), the window setting unit 13 performs window setting processing (step S4).

  In step S4, as shown in FIG. 14, the window setting unit 13 displays the generated horizontal slice image data (upper vertebral body, middle vertebral body, lower vertebral body) using a 2D viewer (step S31).

  Subsequently, for each of the horizontal cross-sectional image data (upper vertebral body, middle vertebral body, lower vertebral body), the window setting unit 13 sets a maximum of 5 cancellous bone regions and cortical bones as shown in FIG. Are designated as a region of interest ROI (step S32).

  Subsequently, the window setting unit 13 acquires the CT value of the designated cancellous bone region and the CT value of the cortical bone region (step S33). Subsequently, the window setting unit 13 (control unit 31) calculates the average value of the CT value of the cancellous bone and the average value of the CT value of the cortical bone (step S34). Subsequently, as shown in FIG. 7, the window setting unit 13 sets the average value of the CT value of the cancellous bone as the minimum value and the average value of the CT value of the cortical bone as the maximum value. WL is calculated and stored in the storage unit 10 (step S35). As described above, the window width WW is the difference between the average value of the cortical bone CT value and the average value of the CT value of the cancellous bone, and the window level WL is the average value of the CT value of the cortical bone and the average value of the cancellous bone. It is an intermediate value from the average value of CT values.

  Returning to FIG. 12, the color image generation unit 14 performs color image generation processing (step S5). Specifically, as shown in FIG. 10, the color image generation unit 14 performs the CT value corresponding to the window width WW and the level WL set by the window setting unit 13 with respect to the CT value in the grayscale image. Color mapping to generate a color image.

  The fusion image generation unit 15 performs a fusion image generation process (step S6). Specifically, for example, the fusion image generation unit 15 aligns a gray image as shown in FIG. 9A and a color image as shown in FIG. In addition, a fusion image shown in FIG. 9C is generated. Specifically, in the image shown in FIG. 9A, an area that is not color mapped and an area that is color mapped in the image shown in FIG. 9B are combined to form a fusion image. Generated. The fusion image is stored in the storage unit 10 as fusion image data 25.

  Subsequently, the medical image processing apparatus 2 determines whether or not the processing has been completed for all the images to be compared (step S7). At this point, only the processing of the image data captured at the reference time has been performed. If the processing has not been completed for all the images to be compared (step S7; No), the medical image processing apparatus 2 returns to step S2.

  In this case, the image reconstruction unit 12 again performs an image reconstruction process (step S2). In this process, for example, a two-dimensional horizontal cross-sectional image of the upper vertebral body, the middle vertebral body, and the lower vertebral body is generated based on the three-dimensional image data four weeks after the reference time, and grayscale image data is stored in the storage unit 10. 22 is stored.

  The medical image processing apparatus 2 determines whether or not the three-dimensional image data at the reference time (immediately after the injury) is being processed (step S3). At this time, 3D image data after 4 weeks is being processed. When it is determined that the three-dimensional image data at the reference time (immediately after being damaged) is not processed (step S3; No), the color image generation unit 14 performs a color image generation process (step S5). Specifically, as shown in FIG. 10, the color image generation unit 14 corresponds to the CT value in the grayscale image according to the window width WW and level WL set in the grayscale image data 22 at the reference time. The CT values are colored to generate a color image.

  Subsequently, the fusion image generation unit 15 performs a fusion image generation process (step S6). Specifically, the fusion image generation unit 15 generates a fusion image shown in FIG. 9C by superimposing the gray image shown in FIG. 9A and the color image shown in FIG. 9B. The generated fusion image is stored in the storage unit 10 as fusion image data 25.

  Subsequently, the medical image processing apparatus 2 determines whether or not the processing has been completed for all the images to be compared (step S7). At this time, the processing of the image data captured after 12 weeks has not yet been performed. If the processing has not been completed for all the images to be compared (step S7; No), the medical image processing apparatus 2 returns to step S2.

  Here, again, the image reconstruction unit 12 performs an image reconstruction process (step S2). Here, for example, based on the three-dimensional image data 12 weeks after the reference time, two-dimensional horizontal cross-sectional images of the upper vertebral body, middle vertebral body, and lower vertebral body are generated and stored as grayscale CT image data 22. Stored in the unit 10.

  The medical image processing apparatus 2 determines whether or not the three-dimensional image data at the reference time (immediately after the injury) is being processed (step S3). At this time, the three-dimensional image data after 12 weeks is processed. When it is determined that the three-dimensional image data at the reference time (immediately after being damaged) is not processed (step S3; No), the color image generation unit 14 performs a color image generation process (step S5). Specifically, the color image generation unit 14 performs color mapping on the CT value corresponding to the window width WW and the level WL set in the reference grayscale image data 22 with respect to the CT value in the grayscale image. To generate a color image.

  Subsequently, the fusion image generation unit 15 performs a fusion image generation process (step S6). Specifically, the fusion image generation unit 15 generates a fusion image (see FIG. 9C) by superimposing a gray image (see FIG. 9A) and a color image (see FIG. 9B). To do. The fusion image is stored in the storage unit 10 as fusion image data 25.

  Subsequently, the medical image processing apparatus 2 determines whether or not the processing has been completed for all the images to be compared (step S7). At this point, only the processing of the image data captured at the reference time has been performed. When the processing has been completed for all the images to be compared (step S7; Yes), the display output unit 16 performs the fusion image display output processing (step S8). Specifically, as shown in FIG. 11, the display output unit 16 displays a comparison between the fusion image at the time of injury and the subsequent fusion image (after 4 weeks and 12 weeks). Thereafter, the medical image processing apparatus 2 ends the process.

  In this diagnosis processing, the fusion image at the time of reference (after 4 weeks and 12 weeks) and the fusion image after that (after 4 weeks and 12 weeks) were sequentially processed. However, the grayscale two-dimensional cross-sectional image data after four weeks and twelve weeks is generated first, and then the window width WW and level WL are set based on the reference two-dimensional cross-sectional image data. Then, the color image generation and the fusion image generation after 4 weeks and 12 weeks may be sequentially performed at the reference time.

  In addition, at the time when the reference 3D image data is acquired from the imaging device 1, the generation of the grayscale 2D cross-sectional image, the generation of window data, the generation of the color image with respect to the reference 3D image data, A fusion image may be generated. The same process may be performed on the three-dimensional image data acquired thereafter after each acquisition of data from the imaging apparatus 1. Then, after all fusion images have been generated, their display output processing may be performed.

  In the above embodiment, the two-dimensional grayscale image is a horizontal cross-sectional image. However, the image is not limited to this, and may be a sagittal cross-sectional image or a coronal cross-sectional image. Good. FIG. 15 shows a fusion image of a sagittal cross section after 4 weeks and 12 weeks after injury.

  As described above in detail, according to this embodiment, there are a grayscale image that displays a region around the vertebral body with good contrast, and a color image that displays the bone mass distribution inside the vertebral body with color enhancement. A fusion image is generated by superposition. This fusion image is an image that emphasizes the internal state of the vertebral body without erasing the image of the region around the vertebral body. For this reason, the internal state of the vertebral body can be appropriately diagnosed by looking at this fusion image.

  In addition, according to this embodiment, as shown in FIG. 11, the display output unit 16 displays a reference fusion image and a fusion image after that (after 4 weeks and 12 weeks) for comparison display. Thus, it is possible to confirm the temporal change of the internal state of the bone inside the fractured vertebral body. With this comparative display, it is possible to visually evaluate the process of bone fusion in the vertebral body and the minute increase in bone mass in an osteoporotic vertebral fracture.

  The images shown in FIG. 11 and FIG. 15, for example, in the case of the first lumbar vertebral body fracture, the time-lapse of the internal state of the fractured vertebral body when conservative treatment is performed by administering the lumbar soft device and teriparatide once a week. Change. As shown in FIG. 11 and FIG. 15, when this comparative display is seen, the administered drug is applied to the fractured vertebral body in any part (cancellous bone or cortical bone) of any bone mass, bone. It can be confirmed whether it is involved in the increase in density. In addition, with this comparison display, not only fractured vertebral bodies but also non-fractured non-fracture vertebral bodies can be image-processed, and the fractured vertebral body and non-fracture vertebral body can be compared and displayed. It is also possible to confirm whether or not there is a difference in bone mass increase between the vertebral body and the non-fracture vertebral body.

  If this medical image analysis system 100 is used, a special device such as a phantom is not required, so that it is relatively simple and easy to grasp changes in bone mass change, temporal changes, and visual changes.

  In the above embodiment, the case where the medical image analysis system 100 confirms the effect when the drug is used for the treatment of the vertebral fracture caused by osteoporosis has been described. However, the present invention is not limited to this. Regardless of the presence or absence of a fracture, the present invention can also be applied to confirm the effects of bisphosphonate preparations, parathyroid hormone (PUH) preparations, and osteoporosis therapeutic agents. Furthermore, it is possible to clarify the difference in bone mass increase and osteogenesis when administration of various therapeutic agents for osteoporosis is used to determine the effect of the preparation.

  Bone density varies from person to person. The difference is particularly significant in patients with osteoporosis. Therefore, the width WW and level WL of the window for performing color mapping of the fusion image in the medical image analysis system 100 in the above embodiment are determined based on the actual CT value of the cancellous bone and the CT value of the cortical bone. For example, as shown in FIG. 16, the window of a person with a high average value of cortical bone CT values and a high average value of cancellous bone CT is W1, and the average value of cortical bone CT values of cancellous bone The window of a person with a low average CT value is W2. In this way, by displaying a fusion image that has a resolution according to the bone density of the person and more precisely expresses the state of the person's vertebral body, changes in the internal state of the vertebral body over time, etc. Can be drawn more clearly.

  In the above embodiment, as the CT value increases, 256 colors from blue (cold color system) to red (warm color system) are provided. However, the present invention is not limited to this. The number of colors may be greater than 256 or less than 256. Also, the color scheme for the CT value can be arbitrarily set. It is not necessary to change the color to a warm color system as the CT value increases.

  Furthermore, between the fusion images at a plurality of time points, the amount of change in the CT value of the same part is obtained by calculation, and the amount of change in the bone amount is calculated based on the correlation between the CT value and the bone density. It may be visualized by an image.

  This medical image analysis system 100 is suitable for clinical use. The program 39 according to each of the above embodiments can be incorporated as an application in a workstation that has rapidly spread in recent years.

  In addition, the hardware configuration and software configuration of the medical image processing apparatus 2 are examples, and can be arbitrarily changed and modified.

  The central part that performs processing of the medical image processing apparatus 2 including the control unit 31, the main storage unit 32, the external storage unit 33, the operation unit 34, the display unit 35, the communication unit 36, the internal bus 30, and the like is dedicated. It can be realized using a normal computer system regardless of the system. For example, a computer program for executing the above operation is stored in a computer-readable recording medium (flexible disk, CD-ROM, DVD-ROM, etc.) and distributed, and the computer program is installed in the computer. Thus, the medical image processing apparatus 2 that executes the above-described processing may be configured. Alternatively, the medical image processing apparatus 2 may be configured by storing the computer program in a storage device included in a server device on a communication network such as the Internet, and downloading it by a normal computer system.

  When the functions of the medical image processing apparatus 2 are realized by sharing an OS (operating system) and an application program, or by cooperation between the OS and the application program, only the application program part is stored in a recording medium or a storage device. May be.

  It is also possible to superimpose a computer program on a carrier wave and distribute it via a communication network. For example, a computer program may be posted on a bulletin board (BBS, Bulletin Board System) on a communication network, and the computer program distributed via the network. The computer program may be started and executed in the same manner as other application programs under the control of the OS, so that the above-described processing may be executed.

  Various embodiments and modifications can be made to the present invention without departing from the broad spirit and scope of the present invention. The above-described embodiments are for explaining the present invention and do not limit the scope of the present invention. In other words, the scope of the present invention is shown not by the embodiments but by the claims. Various modifications within the scope of the claims and within the scope of the equivalent invention are considered to be within the scope of the present invention.

  DESCRIPTION OF SYMBOLS 1 Imaging apparatus, 2 Medical image processing apparatus, 10 Storage part, 11 Data acquisition part, 12 Image reconstruction part, 13 Window setting part, 14 Color image generation part, 15 Fusion image generation part, 16 Display output part, 21 DICOM data , 22 Grayscale CT image data, 23 Window data, 24 Color image data, 25 Fusion image data, 30 Internal bus, 31 Control unit, 32 Main storage unit, 33 External storage unit, 34 Operation unit, 35 Display unit, 36 Communication Part, 39 program, 100 medical image analysis system.

Claims (11)

An image reconstruction unit configured to represent a CT value in gray scale and reconstruct a first CT image of a two-dimensional section including a vertebral body based on three-dimensional image data of a region including a vertebra obtained by computed tomography;
CT for performing color mapping on the first CT image in which the CT value of the cancellous bone region in the reconstructed first CT image is the minimum value and the CT value of the cortical bone region is the maximum value A range setting section for setting a range of values;
Based on the CT value range set by the range setting unit, the first CT image is subjected to color mapping using a plurality of colors with color coding according to the CT value of the range . A color image generation unit that converts the CT image of 1 into a second CT image that represents a CT value in color;
A fusion image generating unit that generates a fusion image by superimposing the first CT image and the second CT image;
A medical image processing apparatus comprising: The image reconstruction unit
Reconstructing the first CT image in the same cross section at the plurality of different time points from each of the three-dimensional image data obtained by computer tomography at a plurality of different time points,
The range setting unit
Based on a CT value of the cancellous bone region and a CT value of the cortical bone region in the first CT image at the reference time point among the plurality of different time points, Set the range,
The color image generation unit
Each of the first CT images in the same cross section at a plurality of different time points is converted into a second CT image in which CT values are expressed in color by performing color mapping in the range set by the range setting unit. And
The fusion image generation unit
The first CT image and the second CT image at the same time point are overlapped to generate the fusion images at a plurality of different time points, respectively.
The medical image processing apparatus according to claim 1. A display output unit for comparing and displaying the fusion image of the same cross section at a plurality of different time points,
The medical image processing apparatus according to claim 2. The range setting unit includes:
The average CT value of the cancellous bone region is the minimum CT value for color mapping,
The average value of CT values of the cortical bone region is set as a maximum value of CT values for performing color mapping, and a range of CT values for performing color mapping is set.
The medical image processing apparatus according to any one of claims 1 to 3. The image reconstruction unit
Reconstructing a plurality of different horizontal cross-sectional CT images of the vertebral body as the first CT image;
The medical image processing apparatus according to any one of claims 1 to 4. The range setting unit includes:
Calculate the average value of the center of the vertebral body of the first CT image and the five points on the front, back, left and right as the average value of the CT value of cancellous bone,
Calculate the average value of three cortical bones including vertebral arches and pedicles as the average CT value of cortical bone.
The medical image processing apparatus according to claim 5. A medical image processing apparatus according to any one of claims 1 to 6;
An imaging device for imaging a medical image processed by the medical image processing device;
A medical image analysis system comprising: An image for reconstructing a first CT image of a two-dimensional cross section including a vertebral body by expressing a CT value in gray scale based on three-dimensional image data of a region including a vertebra obtained by computer tomography using a computer A reconfiguration step;
Using the computer, for the first CT image, the CT value of the cancellous bone region in the reconstructed first CT image is the minimum value, and the CT value of the cortical bone region is the maximum value . A range setting step for setting a range of CT values for performing color mapping;
Using a computer, based on the CT value range set in the range setting step, color mapping using a plurality of colors is performed on the first CT image with color coding according to the CT value in the range. A color image generating step of converting the first CT image into a second CT image representing a CT value in color;
Using a computer, a fusion image generating step of generating a fusion image by superimposing the first CT image and the second CT image;
A medical image processing method. In the image reconstruction step,
Reconstructing the first CT image in the same cross section at the plurality of different time points from each of the three-dimensional image data obtained by computer tomography at a plurality of different time points,
In the range setting step,
Based on a CT value of the cancellous bone region and a CT value of the cortical bone region in the first CT image at the reference time point among the plurality of different time points, Set the range,
In the color image generation step,
Each of the first CT images in the same cross section at a plurality of different time points is converted into a second CT image in which CT values are expressed in color by performing color mapping in the range set by the range setting unit. And
In the fusion image generation step,
The first CT image and the second CT image at the same time point are overlapped to generate the fusion images at a plurality of different time points, respectively.
The medical image processing method according to claim 8. Computer
An image reconstruction unit that represents CT values in gray scale and reconstructs a first CT image of a two-dimensional section including a vertebral body based on three-dimensional image data of a region including a vertebra obtained by computed tomography;
CT for performing color mapping on the first CT image in which the CT value of the cancellous bone region in the reconstructed first CT image is the minimum value and the CT value of the cortical bone region is the maximum value A range setting section for setting the range of values,
Based on the CT value range set by the range setting unit, the first CT image is subjected to color mapping using a plurality of colors with color coding according to the CT value of the range . A color image generation unit that converts one CT image into a second CT image in which CT values are expressed in color;
A fusion image generating unit that generates a fusion image by superimposing the first CT image and the second CT image;
Program to function as. The image reconstruction unit
Reconstructing the first CT image in the same cross section at the plurality of different time points from each of the three-dimensional image data obtained by computer tomography at a plurality of different time points,
The range setting unit includes:
Based on a CT value of the cancellous bone region and a CT value of the cortical bone region in the first CT image at the reference time point among the plurality of different time points, Set the range,
The color image generation unit
Each of the first CT images in the same cross section at a plurality of different time points is converted into a second CT image in which CT values are expressed in color by performing color mapping in the range set by the range setting unit. And
The fusion image generation unit
The first CT image and the second CT image at the same time point are overlapped to generate the fusion images at a plurality of different time points, respectively.
To make the computer work,
The program according to claim 10.

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