JP7628828B2 - Medical image processing device and medical image diagnostic device - Google Patents

Description

The embodiments disclosed in this specification and the drawings relate to a medical image processing device and a medical image diagnostic device.

The liver is an organ that receives dual blood circulation from the artery and the portal vein. In a healthy individual, 20-30% of blood flow is from the artery, and 70-80% is from the portal vein. However, when the individual is ill, the ratio of blood flow between the artery and the portal vein (hereafter referred to as the hepatic artery/portal vein blood flow ratio) differs. In perfusion tests, there is a technique for calculating the hepatic artery/portal vein blood flow ratio. The hepatic artery/portal vein blood flow ratio is presented by superimposing a color value or the like corresponding to the blood flow ratio on the slice cross section. However, with this presentation method, the user can only check the spatial distribution of the hepatic artery/portal vein blood flow ratio for each slice, so it takes time to check the hepatic artery/portal vein blood flow ratio for the entire liver.

JP 2016-101482 A JP 2012-217548 A

One of the problems that the embodiments disclosed in this specification and the drawings attempt to solve is to grasp characteristic quantities such as the arterial/portal blood flow ratio of the entire liver in a short period of time. However, the problems that the embodiments disclosed in this specification and the drawings attempt to solve are not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described below can also be positioned as other problems.

The medical image processing device according to the embodiment has an acquisition unit, a generation unit, and a display control unit. The acquisition unit acquires feature amount data relating to the feature amount of the liver based on volume data of the liver. The generation unit generates a map in which the feature amount data is projected onto a two-dimensional development having a plurality of display sections corresponding to a plurality of liver segments determined based on the vascular course of the liver. The display control unit displays the map.

FIG. 1 is a diagram showing an example of the configuration of a medical image processing system including a medical image processing apparatus according to this embodiment. FIG. 2 is a diagram showing an example of the configuration of the medical image processing apparatus shown in FIG. FIG. 3 is a diagram showing a procedure of an example of processing by the medical image processing apparatus of FIG. FIG. 4 is a schematic diagram showing the relationship between the liver segments and the portal vein. FIG. 5 is a diagram showing an example of a liver circular map, which is an example of a liver spread map. FIG. 6 is a diagram showing a procedure for generating a circular liver map according to the first generation method. FIG. 7 is a schematic diagram showing the relationship between liver segments, reference positions, and inflow points. FIG. 8 is a diagram showing an example of a template of a circular liver map according to the first generation method. FIG. 9 is a diagram showing a schematic diagram of a process for generating a circular liver map. FIG. 10 is a diagram showing the steps of a second method for generating a circular liver map. FIG. 11 is a schematic diagram showing liver segments, reference positions, inflow points and reference planes. FIG. 12 is a diagram showing an example of a template of a circular liver map according to the second generation method. FIG. 13 is a diagram illustrating another example of a method for arranging display regions according to the second generation method. FIG. 14 is a diagram illustrating another example of a method for arranging display regions according to the second generation method. FIG. 15 is a diagram showing a procedure for generating a circular liver map according to the third generation method. FIG. 16 is a schematic diagram showing liver segments, reference positions, inflow points and sizes of liver segments. FIG. 17 is a diagram showing an example of an intermediate stage of a liver circular map template according to the third generation method. FIG. 18 is a diagram showing an example of a template for a liver circular map according to the generation method of FIG. FIG. 19 is a diagram showing an example of an intermediate stage of another liver circular map template according to the third generation method. FIG. 20 is a diagram showing an example of a template for a liver circular map according to the generation method of FIG. FIG. 21 is a diagram showing an example of a display screen according to the first display example. FIG. 22 is a diagram showing an example of a display screen according to the second display example. FIG. 23 is a diagram showing another example of the display screen according to the second display example. FIG. 24 is a diagram showing an example of a display screen according to the third display example. FIG. 25 is a diagram showing another example of the display screen according to the display example 3. In FIG. FIG. 26 is a diagram showing another example of the display screen according to the display example 3. In FIG. FIG. 27 is a diagram showing an example of superimposing a circular liver map and a blood vessel region according to Display Example 4. In FIG. FIG. 28 is a diagram showing an example of a display of a circular liver map, a blood vessel region, and a tumor region superimposed on each other according to the fourth display example. FIG. 29 is a diagram showing an example of a display screen according to the fifth display example. FIG. 30 is a diagram showing an example of a display screen according to the sixth display example. FIG. 31 is a diagram showing an example of a circular liver map (hepatic segment resection) according to the seventh display example. FIG. 32 is a diagram showing another example of the liver circular map according to the seventh display example (without liver segment color). FIG. 33 is a diagram showing another example of the liver circular map according to the seventh display example (liver segments displayed with dotted lines). FIG. 34 is a diagram showing another example (reconstruction) of the liver circular map according to the seventh display example. FIG. 35 is a diagram showing an example of a display screen according to the eighth display example. FIG. 36 is a diagram showing an example of a liver spread map according to the first modification.

Below, we will explain in detail the embodiments of the medical image processing device and medical image diagnostic device with reference to the drawings.

Figure 1 is a diagram showing an example of the configuration of a medical image processing system including a medical image processing device according to this embodiment. As shown in Figure 1, the medical image processing system has a medical image processing device 1, a medical image diagnostic device 2, and a medical image storage device 3, which are communicatively connected to each other via a network. The medical image processing device 1 is a computer that processes medical images such as liver volume data (three-dimensional medical image data) related to a subject. The medical image diagnostic device 2 is a computer system including a medical imaging mechanism and a computer that performs medical imaging on an imaging region including the liver of the subject to generate liver volume data. The medical image storage device 3 is a computer that stores medical images generated by the medical image processing device 1, the medical image diagnostic device 2, etc. The medical image storage device 3 is realized by a computer included in a network system such as a PACS (Picture Archiving and Communication System), a HIS (Hospital Information System), or a RIS (Radiology Information System).

The medical image diagnostic device 2 may be a single modality device such as an X-ray computed tomography device (X-ray CT device), a magnetic resonance imaging device (MRI device), an X-ray diagnostic device, a PET device, a SPECT device, or an ultrasound diagnostic device, or may be a multi-modality device such as a PET/CT device, a SPECT/CT device, a PET/MRI device, or a SPECT/MRI device.

When the medical image diagnostic device 2 is an X-ray CT device, the gantry of the X-ray CT device rotates the X-ray tube and the X-ray detector around the subject while irradiating the subject with X-rays from the X-ray tube, and the X-rays that pass through the subject are detected by the X-ray detector. The X-ray detector generates an electrical signal having a peak value according to the detected X-ray dose. The electrical signal is subjected to signal processing such as A/D conversion by a data acquisition circuit. The electrical signal after A/D conversion is called projection data or sinogram data. The console generates a CT image based on the projection data or sinogram data. Projection data and sinogram data are types of raw data. A CT image is a type of medical image.

When the medical image diagnostic device 2 is an MRI device, the gantry of the MRI device repeatedly applies a gradient magnetic field via a gradient coil and an RF pulse via a transmission coil under the application of a static magnetic field via a static magnetic field magnet. An MR signal is emitted from the subject due to the application of the RF pulse. The emitted MR signal is received via a receiving coil. The received MR signal is subjected to signal processing such as A/D conversion by a receiving circuit. The MR signal after A/D conversion is called k-space data. The console generates an MR image based on the k-space data. The k-space data is a type of raw data. The MR image is a type of medical image.

When the medical image diagnostic device 2 is an ultrasound diagnostic device, the ultrasound probe of the ultrasound diagnostic device transmits ultrasound beams from multiple ultrasound transducers into the subject's body and receives ultrasound reflected from within the subject's body via the ultrasound transducers. The ultrasound transducers generate electrical signals having a peak value corresponding to the sound pressure of the received ultrasound. The electrical signals are A/D converted by an A/D converter provided in the ultrasound probe or the like. The electrical signals after A/D conversion are called echo data. The device body generates an ultrasound image based on the echo data. Echo data is a type of raw data. An ultrasound image is a type of medical image.

When the medical image diagnostic device 2 is a PET device, the gantry of the PET device generates digital data having digital values related to the energy value and detection position of the pair of gamma rays by simultaneously measuring a pair of 511 keV gamma rays generated by the annihilation of a positron generated from a radioactive nuclide accumulated in the subject and an electron present around the radioactive nuclide using a coincidence measurement circuit. This digital data is called coincidence data or sinogram data. The console generates a PET image based on the coincidence data or sinogram data. Coincidence data and sinogram data are types of raw data. A PET image is a type of medical image. The same applies to a SPECT device.

When the medical image diagnostic device 2 is an X-ray diagnostic device, the X-ray diagnostic device generates X-rays from an X-ray tube provided in a C-arm. An X-ray detector such as an FPD (Flat Panel Display) provided in the C-arm or independent of the C-arm receives the X-rays generated from the X-ray tube and transmitted through the subject. The X-ray detector generates an electrical signal having a peak value corresponding to the detected X-ray dose, and performs signal processing such as A/D conversion on the electrical signal. The electrical signal after A/D conversion is called projection data or an X-ray image. In the case of cone beam CT, etc., the projection data or X-ray image is also used as raw data. An X-ray image is a type of medical image.

Figure 2 is a diagram showing an example of the configuration of the medical image processing device 1 in Figure 1. As shown in Figure 2, the medical image processing device 1 has a processing circuit 11, a communication interface 12, a display device 13, an input interface 14, and a storage device 15.

The processing circuit 11 has a processor such as a CPU (Central Processing Unit). The processor executes programs that realize the image processing function 111, feature acquisition function 112, map generation function 113, and/or display control function 114. The programs for realizing the image processing function 111, feature acquisition function 112, map generation function 113, and/or display control function 114 may be recorded on a non-transitory recording medium that can be read by a processor such as the storage device 15. Each of the functions 111-114 is not limited to being realized by a single processing circuit. A processing circuit may be configured by combining multiple independent processors, and each processor may execute a program to realize each of the functions 111-114.

By implementing the image processing function 111, the processing circuitry 11 performs various image processing on medical images such as volume data of the subject's liver. Image processing can include image correction, image conversion, image processing, feature extraction, image recognition, and three-dimensional image processing.

By implementing the feature acquisition function 112, the processing circuitry 11 acquires data on the features of the liver (hereinafter referred to as feature data) based on the volume data of the liver of the subject. For example, a parameter related to blood flow in the liver is used as the feature. The feature data is data in which features are assigned to the entire volume data or to a partial area including the liver.

By implementing the map generation function 113, the processing circuitry 11 generates a map in which the feature data acquired by the feature acquisition function 112 is projected onto a two-dimensional unfolded view (template) having multiple display sections that respectively correspond to multiple liver segments determined based on the vascular course of the liver. The processing circuitry 11 generates a template using the blood vessels inside the liver as the reference position, and projects the feature data onto the template. This generates the above map. Hereinafter, the generated map will be referred to as a liver unfolded map.

By implementing the display control function 114, the processing circuitry 11 displays various information. For example, the processing circuitry 11 displays the liver unfolded map generated by the map generation function 113 on the display device 13.

The communication interface 12 is an interface that connects to the medical image diagnostic device 2, the medical image storage device 3, the PACS, the HIS, the RIS, etc., via a LAN (Local Area Network) or the like. The communication interface 12 transmits and receives various information to and from the connected devices.

The display device 13 displays various information according to the display control function 114 of the processing circuit 11. As the display device 13, a liquid crystal display (LCD), a cathode ray tube (CRT) display, an organic electroluminescence display (OELD), a plasma display, or any other display can be used as appropriate. The display device 13 may also be a projector.

The input interface 14 accepts various input operations from the user, converts the accepted input operations into electrical signals, and outputs the electrical signals to the processing circuit 11. Specifically, the input interface 14 is connected to input devices such as a mouse, keyboard, trackball, switch, button, joystick, touchpad, and touch panel display. The input interface 14 outputs electrical signals corresponding to the input operations to the input devices to the processing circuit 11. The input devices connected to the input interface 14 may also be input devices provided in other computers connected via a network or the like. The input interface 14 may also be a voice recognition device that converts voice signals collected by a microphone into instruction signals.

The storage device 15 is a storage device such as a ROM (Read Only Memory), RAM (Random Access Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or integrated circuit storage device that stores various information. The storage device 15 stores, for example, medical images and various programs. In addition to the above storage devices, the storage device 15 may be a drive device that reads and writes various information between a portable storage medium such as a CD (Compact Disc), a DVD (Digital Versatile Disc), or a flash memory, or a semiconductor memory element. The storage device 15 may be in another computer connected to the medical image processing device 1 via a network.

Next, we will explain an example of processing by the medical image processing device 1.

3 is a diagram showing a procedure of a processing example of the medical image processing device 1. As shown in FIG. 3, the processing circuit 11 extracts the liver region, the hepatic artery region, and the portal vein region from the time-series volume data of the liver by implementing the image processing function 111 (step SA1). The time-series contrast volume data of the liver (three-dimensional medical image data) may be generated by any of the above medical image diagnostic devices 2, but is assumed to be generated by an X-ray computed tomography device. In this case, the X-ray computed tomography device repeatedly scans the abdominal region including the liver of the subject for any imaging period, for example, after a contrast agent is injected into the subject. The imaging period includes multiple time phases in which the contrast agent flows in the liver. The imaging period may be set in advance as an imaging condition, or may be dynamically determined during the imaging period. The X-ray computed tomography device repeatedly scans to collect time-series volume data of the abdominal region including the liver over the imaging period. The volume data is called time-series contrast volume data.

In step SA1, the processing circuitry 11 extracts the liver region, the hepatic artery region, and the portal vein region from the time-series contrast volume data using existing image processing such as threshold processing, texture analysis, landmark analysis, and image recognition processing. The liver region is an image region related to the image, the hepatic artery region is an image region related to the hepatic artery, and the portal vein region is an image region related to the portal vein. The liver region, the hepatic artery region, and the portal vein region may be extracted manually in accordance with a user instruction via the input interface 14. Extraction of these regions may be performed on the volume data of all time phases of the time-series contrast volume data, or on the volume data of several time phases.

After step SA1 is performed, the processing circuitry 11 divides the liver region into multiple liver segments by implementing the image processing function 111 (step SA2). In step SA2, the processing circuitry 11 divides the liver region into multiple liver segments based on the vascular course of the portal vein region and/or the hepatic artery region. Any liver segment may be used, such as the Healey & Schroy liver segment or the Couinaud liver segment, but in the following description, the Couinaud liver segment will be used.

As shown in FIG. 4, the liver is divided into sub-segments: caudate lobe S1, left lateral posterior region S2, left lateral anterior region S3, left medial region S4, right anterior inferior region S5, right posterior inferior region S6, right posterior superior region S7, and right anterior superior region S8. The portal vein is connected to liver segments S1-S8. The base of the portal vein is called the portal vein main frame. The processing circuitry 11 divides the liver region into eight liver segments using image recognition processing or the like, based on the positional relationship between the vascular course of the portal vein region and/or the hepatic artery region and the liver region. The processing circuitry 11 may divide the liver segments according to instructions from the user via the input interface 14.

As shown in FIG. 3, when step SA2 is performed, the processing circuitry 11 acquires feature amount data by implementing the feature amount acquisition function 112 (step SA3). In step SA3, the processing circuitry 11 performs perfusion analysis on the time-series contrast volume data to calculate a parameter related to blood flow in the liver (hereinafter referred to as liver blood flow parameter) as a feature amount of the liver for each pixel of the liver region of the time-series contrast volume data. Specifically, the processing circuitry 11 calculates the hepatic artery blood flow rate, which is the blood flow rate flowing from the hepatic artery to the liver, and the portal vein blood flow rate, which is the blood flow rate flowing from the portal vein to the liver, for each pixel of the liver region. Then, the processing circuitry 11 calculates the hepatic artery/portal vein blood flow ratio, which is the ratio between the hepatic artery blood flow rate and the portal vein blood flow rate, for each pixel. Data on the spatial distribution of the portal vein blood flow rate, hepatic artery blood flow rate, and hepatic artery/portal vein blood flow ratio for each pixel is acquired as feature amount data.

The feature data does not necessarily have to be calculated by the processing circuitry 11. For example, another computer may calculate the feature data based on the time-series contrast volume data of the subject's liver using the above method. In this case, the processing circuitry 11 may obtain the feature data from the other computer via the communication interface 12 or the like. In addition, the feature is not limited to liver blood flow parameters, and may be any analysis parameter obtained from volume data, such as liver fat mass.

After step SA3 is performed, the processing circuitry 11 generates a liver unfolded map by implementing the map generation function 113 (step SA4). In step SA4, the processing circuitry 11 projects the feature data (e.g., liver blood flow parameters) acquired in step SA3 onto a two-dimensional unfolded view (template) having multiple display sections corresponding to multiple liver segments S1-S8 determined based on the vascular course of the liver, thereby generating a liver unfolded map. The feature data of the entire liver region is projected onto the liver unfolded map. As an example of the liver unfolded map, a circular liver map is generated.

Figure 5 is a diagram showing an example of a liver circular map I1, which is an example of a liver unfolded map. The liver circular map is a two-dimensional map in which feature data is projected onto a circular template whose center point corresponds to the reference position of the portal vein region. As an example, the liver portal area is used as the reference position. In the liver circular map template, a plurality of display sections S1-S8 corresponding to the plurality of liver segments S1-S8 are arranged around a center point according to the positional relationship of each of the plurality of liver segments S1-S8 with respect to the reference position. The processing circuitry 11 determines the arrangement of the plurality of display sections S1-S8 in the template based on the distance and/or direction between the reference position and the plurality of liver segments S1-S8. The processing circuitry 11 can also determine the size of each of the plurality of display sections S1-S8 based on the size of each of the plurality of liver segments S1-S8. Note that the positional relationship and/or size of each display section S1-S8 may be a preset standard value regardless of the subject to be examined.

As shown in FIG. 5, each display area S1-S8 has a circular or sector shape. A circular template is formed by pasting together a plurality of display areas S1-S8 according to the positional relationship of the plurality of liver segments S1-S8. The liver circular map template is expressed in a coordinate system similar to polar coordinates. The coordinate system is expressed as (r, θ), where θ roughly reflects the angle around the portal vein core line passing through the reference position of the portal vein region, and r reflects the distance from the reference position. The liver circular map can also be expressed as a liver polar map. Details of the method for generating the liver unfolded map and the liver circular map will be described later. In this embodiment, the reference position is set on the portal vein region, but is not limited to this, and may be set on the hepatic artery region.

When step SA4 is performed, the processing circuitry 11 displays the liver unfolded map generated in step SA4 by implementing the display control function 114 (step SA5). In step SA5, the processing circuitry 11 displays the liver unfolded map in various layouts on the display device 13.

As shown in FIG. 5, the processing circuit 11 displays the liver unfolded map in a color according to the feature value. The correspondence between the feature value and the color value is registered in a color table. For example, the feature value and the color value are associated so that the feature value changes continuously from red to green to blue as it goes from high to low. The processing circuit 11 displays a liver circular map I11 that expresses the spatial distribution of the feature value in color by referring to the color table. The liver circular map I11 is a map in which the feature value of the entire liver is projected onto a two-dimensional plane for each liver segment, so that the user can observe and understand the spatial distribution of the feature value of the entire liver at a glance by observing the liver circular map I11. Note that the feature value may be associated with other display parameter values such as gray value and transparency instead of color value.

When step SA5 is performed, the processing of the medical image processing device 1 ends.

Next, we will explain the details of how to generate the liver circular map in step SA4 of Figure 3.

(First Generation Method)
Fig. 6 is a diagram showing a procedure for generating a circular liver map according to the first generation method. As shown in Fig. 6, the processing circuitry 11 sets a reference position in the portal vein region extracted in step SA1 (step SB1). As shown in Fig. 7, the reference position P0 is set at a branch point of the portal vein main frame that passes through the center line of the portal vein region. The reference position P0 may be set by image processing, or may be set at a position designated by the user via the input interface 14.

After step SB1 is performed, the processing circuit 11 calculates the distance between each liver segment and the reference position (step SB2). As the distance between each liver segment and the reference position, for example, as shown in FIG. 7, the portal vein center line length from the reference position P0 to the inflow points P1-P8 of each liver segment S1-S8 may be calculated. The inflow points P1-P8 are set at points where the portal vein region enters the liver segments S1-S8. The inflow points P1-P8 may be set by image processing, or may be set at positions specified by the user via the input interface 14. The portal vein center line length is defined as the length of the center line (center line) of the portal vein region.

The distance between each liver segment and the reference position may be calculated as the straight-line distance from the reference position to each inflow point. As another example, the distance between each liver segment and the reference position may be calculated as the length from the reference position to a representative point of each liver segment. The representative point may be set to the center of gravity, center point, or specified point of the liver segment. The length may be the straight-line distance, the portal vein core length, or a combination of the straight-line distance and the portal vein core length.

After step SB2 is performed, the processing circuitry 11 generates a template of a circular liver map (step SB3). More specifically, the processing circuitry 11 generates a circular template in which a plurality of display sections are arranged according to the distance calculated in step SB2, with the reference position set in step SB1 as the center point. Step SB3 will be described in detail below.

As shown in FIG. 8, the template of the circular liver map is divided into an inner region and an outer region in the radial direction. The processing circuit 11 compares the distance calculated in step SB2 with a threshold value, and places display sections corresponding to liver segments that are closer than the threshold value in the inner region, and display sections corresponding to liver segments that are closer than the threshold value in the outer region. The display sections in the inner region have a fan shape, and the display sections in the outer region have a circular ring shape. The circular template is formed by pasting together multiple display sections in the inner region and multiple display sections in the outer region.

In FIG. 8, for example, since the liver segments S2, S3, S6, and S7 are located at a distance greater than the threshold, the display segments S2, S3, S6, and S7 are arranged in the outer region, and since the liver segments S1, S4, S5, and S8 are located at a distance less than the threshold, the display segments S1, S4, S5, and S8 are arranged in the inner region. The positional relationship between the display segments S2, S3, S6, and S7 in the outer region and the positional relationship between the display segments S1, S4, S5, and S8 in the inner region is set in advance according to the positional relationship between the liver segments. The sizes of the display segments S2, S3, S6, and S7 in the outer region are set to be equal, and the sizes of the display segments S1, S4, S5, and S8 in the inner region are also set to be equal. Note that, although the display segments S2, S3, S6, and S7 and the display segments S1, S4, S5, and S8 are arranged alternately in the circumferential direction in FIG. 8, they may be arranged to coincide in the circumferential direction.

After step SB3, the processing circuit 11 projects the feature data for each of the liver segments S1-S8 onto a template of a liver circular map to generate a liver circular map (step SB4). In step SB4, the processing circuit 11 develops each of the liver segments S1-S8 on a cut surface according to the running direction of the portal vein region connected to the liver segment, associates each first pixel of the cut surface in the developed liver segment with each second pixel of the display section corresponding to the liver segment, and assigns the projected feature value of a projection line that is perpendicular to the cut surface, passes through the first pixel, and penetrates the developed liver segment to the second pixel of the display section. This generates a liver circular map. Step SB4 will be described in detail below. Note that the following description of step SB4 will be given for the processing of liver segment S7 as an example, but similar processing can be performed for other liver segments.

As shown in FIG. 9, the processing circuit 11 first sets a cutting plane 71 in the liver segment 70. The cutting plane 71 is set so as to follow the core line 72 of the portal vein region that connects to the liver segment 70. Specifically, the cutting plane 71 is set on a plane that cuts from one surface of the liver segment along the core line 72 and reaches the core line 72. Here, the end P71 of the core line 72 that passes through the liver segment 70 is called the end point. The cutting plane 71 is defined as a plane surrounded by a line segment that connects the inflow point P7 and the end point P71 along the core line 72 and a line segment that connects the inflow point P7 and the end point P71 along the surface of the liver segment 70. Once the cutting plane 71 is set, the processing circuit 11 cuts and unfolds the liver segment 70 along the cutting plane 71.

After unfolding, the processing circuit 11 performs correspondence between anatomically corresponding pixels in the unfolded liver segment 70 and the display segment 75 corresponding to the liver segment 70. More specifically, the processing circuit 11 corresponds each pixel on the cut surface 71 of the unfolded liver segment 70 to each pixel of the display segment 75. For example, first, a point on the contour 73 of the cut surface 71 of the liver segment 70 is corresponded to a point on the contour 76 of the display segment 75. Here, the center point 761 of the radial inner edge of the display segment 75 is matched to the inflow point P7 of the liver segment 70, and the center point 762 of the radial outer edge of the display segment 75 is matched to the end point P71 of the liver segment 70. In addition, one end point 763 and the other end point 764 of the radially inner edge of the display area 75 correspond to one end point P72 and the other end point P73 of the inflow point P7 side edge of the cut surface 71, respectively, and one end point 765 and the other end point 766 of the radially outer edge of the display area 75 correspond to one end point P74 and the other end point P75 of the end point P71 side edge of the cut surface 71, respectively.

Next, the processing circuit 11 calculates the correspondence between the pixels inside the cross section 71 and the pixels inside the display area 75 based on the correspondence between the contour points. As described above, the display area 75 is defined in a two-dimensional coordinate system obtained by performing a coordinate transformation according to the correspondence on the two-dimensional coordinate system related to the cross section 71. In the two-dimensional coordinate system, the angle around the center point of the template is defined as the distance from the core line 72 or the inflow point P7 on a plane (hereinafter referred to as the inflow plane) passing through the inflow point P7 of the liver segment 70, and the radial distance of the template is defined as the distance along the core line 72 from the inflow point P7. In this way, the display area 75 is defined in a coordinate system similar to a polar coordinate system.

The correspondence (mapping) from each image of the liver segment 70 to the corresponding pixel of the display section 75 forms a coordinate transformation formula. The coordinate transformation formula is derived for each of the liver segments S1-S8. The coordinate transformation formula is stored in the storage device 15 etc. in correspondence with the identifier of the liver segment S1-S8.

After the correspondence, the processing circuitry 11 sets, for each pixel 701 on the cross section 71, a projection line 77 that passes through the pixel 701, intersects the cross section 71 at right angles, and penetrates the liver segment 70. A projection value is calculated based on the feature values assigned to each of the pixels 701 through which the projection line 77 passes. As the projection value, any statistical value according to the purpose may be calculated, such as the average value, integral value, minimum value, maximum value, or the like, of the feature values assigned to each of the pixels 701 through which the projection line 77 passes. The type of statistical value can be specified by the user via the input interface 14. The processing circuitry 11 then assigns the calculated projection value to the corresponding pixel 78 in the display area 75. In this way, a circular liver map is generated.

When step SB4 is performed, the process of generating a liver circular map by the processing circuit 11 (step SA4) ends.

As described above, according to the first generation method, it is possible to generate a circular liver map in which the spatial distribution of the feature amount of the entire liver is expanded on a two-dimensional circular plane while maintaining the positional relationship between the liver segments based on the portal vein region. By observing the circular liver map, the user can check the spatial distribution of the feature amount of the entire liver at a glance. For example, if the feature amount is a liver blood flow parameter such as the hepatic artery/portal vein blood flow ratio, the user can instantly evaluate the blood flow abnormality. In addition, the first generation method determines the arrangement of the display sections on the template of the circular liver map based only on the distance between the reference position and each liver segment. Therefore, according to the first generation method, the display sections can be arranged almost uniformly regardless of the individual differences of the subject, compared to the second and third generation methods that take into account the direction, and the circular liver map can be generated easily and with a low calculation load. In addition, since the arrangement of the display sections is almost uniform, it is easy to observe the circular liver map across multiple subjects.

In the above embodiment, the placement of the display sections on the template is determined according to the distance between the reference position and each liver segment. However, the placement of the display sections may be determined according to anatomical knowledge and experience. More specifically, in the above embodiment, the display sections corresponding to liver segments whose distance is below the threshold are placed in the inner region, and the display sections corresponding to liver segments whose distance is above the threshold are placed in the outer region, but the display sections to be placed in the inner region and the display sections to be placed in the outer region may be determined according to anatomical knowledge and experience.

(Second Generation Method)
Fig. 10 is a diagram showing a procedure for generating a circular liver map according to the second generation method. The second generation method 2 is an advanced version of the first generation method. As shown in Fig. 10, the processing circuitry 11 sets a reference position of the portal vein region extracted in step SA1 (step SC1). The process of step SC1 is the same as the process of step SB1.

After step SC1 is performed, the processing circuit 11 calculates the distance and direction between each liver segment and the reference position (step SC2). The distance between each liver segment and the reference position is calculated in the same manner as in step SB2. The direction between each liver segment and the reference position is calculated as the left or right direction with respect to a plane that passes through the reference position (hereinafter referred to as the reference plane). For example, it is calculated as follows:

As shown in FIG. 11, the processing circuit 11 calculates whether each inflow point P1-P8 of each liver segment S1-S8 is on the left or right side of the reference plane 60 when viewed from an arbitrary line of sight. The direction of the liver segment with the inflow point on the left side is calculated as "left", and the direction of the liver segment with the inflow point on the right side is calculated as "right". Specifically, vectors from the reference position P0 to each inflow point P1-P8 are calculated, and the direction of each vector is compared with the direction of the reference plane 60. Then, the liver segment related to the vector on the left side of the reference plane 60 is classified as the "left" direction, and the liver segment related to the vector on the right side is classified as the "right" direction. In this way, the direction differs depending on the line of sight. For example, in the case of FIG. 11, the liver segments S5-S8 are identified as the "left" direction, and the liver segments S1-S4 are identified as the "right" direction. The line of sight direction may be set in advance, or may be specified by the user via the input interface 14.

After step SC2, the processing circuitry 11 generates a template of a circular liver map (step SC3). More specifically, the processing circuitry 11 generates a template in which a plurality of display sections are assigned according to the distance and direction calculated in step SC2, centered on the reference position set in step SC1. Step SC3 will be described in detail below.

As shown in FIG. 12, similar to step SB3, each display section is divided into an inner region or an outer region according to the distance between each liver segment and the reference position. Then, for each of the inner and outer regions, each display section is arranged according to the direction calculated in step SC3. For example, if display sections S1, S4, S5, and S8 are divided into the inner region, and the directions of display sections S1, S4, S5, and S8 are "right", "right", "left", and "left", respectively, display sections S1 and S4 are arranged on the left side of the inner region, and display sections S6 and S8 are arranged on the right side. The same applies to the outer region.

After step SC3, the processing circuit 11 projects the feature data for each liver segment S1-S8 onto a template to generate a circular liver map (step SC4). The processing of step SC4 may be performed in the same manner as the processing of step SB4.

When step SC4 is performed, the process of generating a circular liver map by the processing circuit 11 ends.

Note that the above procedure is an example, and the present embodiment is not limited to this. For example, the method of arranging the display sections in step SC3 is not limited to the above method.

In step SC3, the processing circuitry 11 sets an axial plane 62 that intersects with the liver region 61, as shown in FIG. 13. The axial plane 62 corresponds to the surface of the template. The processing circuitry 11 projects the inflow points P1-P8 of the liver segments S1-S8 onto the axial plane 62, and determines the arrangement of each display section S1-S8 in the template according to the positional relationship of the inflow points P1-P8 projected onto the axial plane 62.

The projection destination of the inflow points P1-P8 of the liver segments S1-S8 is not limited to the axial section 62. For example, as shown in FIG. 14, the processing circuitry 11 may project the inflow points P1-P8 onto a plane 63 that is perpendicular to the reference plane 60 and intersects with the liver region 61. The processing circuitry 11 determines the arrangement of each display section S1-S8 in the template according to the positional relationship of the inflow points P1-P8 projected onto the plane 63.

As described above, the second generation method determines the layout of the display sections on the template of the circular liver map based on the distance and direction between the reference position and each liver segment. Therefore, compared to the first generation method, the second generation method can generate a circular liver map that reflects individual differences between subjects. This makes it possible to accurately grasp the spatial distribution of features such as liver blood flow parameters for each subject.

(Third Generation Method)
15 is a diagram showing a procedure for generating a circular liver map according to the third generation method. As shown in Fig. 15, the processing circuitry 11 sets a reference position of the portal vein region extracted in step SA1 (step SD1). The process of step SD1 is the same as the process of step SB1.

After step SD1 is performed, the processing circuit 11 calculates the distance and direction between each liver segment and the reference position (step SD2). The processing of step SD2 is similar to the processing of step SC2.

After step SD2, the processing circuit 11 generates a liver circular map template (step SD3). The processing of step SD3 is similar to the processing of step SC3.

After step SD3, the processing circuit 11 determines the size of each display section according to the size of each liver segment (step SD4). The size of each liver segment is determined by the area or volume of the liver segment. For example, as shown in FIG. 16, the area may be determined by the area of the surface (inflow surface) A1-A8 to which the portal vein region of each liver segment is connected.

17, in step SD3, the display sections S6 and S7 are assigned to the outer left region of the template, the display sections S2 and S3 to the outer right region, the display sections S5 and S8 to the inner left region, and the display sections S1 and S4 to the inner right region. In this case, as shown in FIG. 18, the processing circuit 11 makes the area ratio of the two display sections in each of the above regions of the template match the size ratio of the corresponding two liver segments. For example, when the size ratio of the liver segment S6 to the liver segment S7 is 3:2, the processing circuit 11 determines the area ratio of the display section S6 to the display section S7 in the outer left region of the template to 3:2, as shown in FIG. 18. The arrangement of the display section S6 and the display section S7 in the outer left region is determined in advance according to the anatomical positions of the liver segment S6 and the liver segment S7. The area ratio of the other display sections in the template may be determined in the same manner.

In step SD2, the direction may not be calculated, and only the distance may be calculated. In the case where only the distance is calculated, multiple display sections are selectively assigned to each of the outer region and the inner region in step SD3. For example, as shown in FIG. 19, display sections S2, S3, S6, and S7 are assigned to the outer region of the template, and display sections S1, S4, S5, and S8 are assigned to the inner region. Even in this case, the processing circuit 11, as in the above method, matches the area ratio of the four display sections in each of the above regions of the template to the size ratio of the corresponding four liver segments. For example, as shown in FIG. 20, the processing circuit 11 matches the area ratio of the display sections S2, S3, S6, and S7 in the outer region to the area ratio of the liver segments S2, S3, S6, and S7. The arrangement of the display sections S2, S3, S6, and S7 in the outer region is determined in advance according to the anatomical positions of the liver segments S2, S3, S6, and S7.

After step SD4, the processing circuit 11 projects the feature data for each liver segment S1-S8 onto a template to generate a circular liver map (step SD5). The processing of step SD5 may be performed in the same manner as the processing of step SB4.

When step SD5 is performed, the process of generating a liver circular map by the processing circuit 11 ends.

As described above, the third generation method determines the layout of the display sections on the template of the circular liver map based on the distance and direction between the reference position and each liver segment, as well as the size of each liver segment. Therefore, compared to the first and second generation methods, the third generation method can generate a circular liver map that reflects individual differences between subjects. This makes it possible to accurately grasp the spatial distribution of features such as liver blood flow parameters for each subject.

Next, various examples of displaying a circular liver map using the display control function 114 will be described. Note that the distribution of gray shades in the figures corresponds to the distribution of feature values or liver blood flow parameter values, but is added to aid in understanding the circular liver map and has no clinical significance unless otherwise specified.

(Display example 1)
21 is a diagram showing an example of a display screen IS1 according to the display example 1. As shown in FIG. 21, the processing circuit 11 displays a liver circular map I2 and a color bar I3 related to the hepatic artery/portal blood flow ratio side by side on the display screen IS1. In the liver circular map I2, a color value according to the hepatic artery/portal blood flow ratio is assigned to each pixel, and the liver circular map I2 is displayed in a color according to the color value. As described above, the liver circular map I2 represents the spatial distribution of the hepatic artery/portal blood flow ratio of the entire liver on one plane by dividing it into liver segments, so that the user can check the spatial distribution of the hepatic artery/portal blood flow ratio of the entire liver at a glance by observing the color distribution on the liver circular map I2, and can instantly evaluate the blood flow abnormality.

As shown in FIG. 21, the color bar I3 is a graphic that represents the correspondence between the hepatic artery/portal blood flow ratio and a color value or color. The liver circular map I2 and the color bar I3 are displayed side by side, allowing the user to instantly associate the color with the hepatic artery/portal blood flow ratio.

(Display example 2)
The processing circuitry 11 in display example 2 displays two liver circular maps side by side based on at least two feature data: portal vein blood flow, arterial blood flow, the ratio between portal vein blood flow and arterial blood flow, and fat mass.

Figure 22 is a diagram showing an example of a display screen IS2 according to display example 2. As shown in Figure 22, the processing circuit 11 displays a liver circular map I4 relating to portal vein blood flow and a liver circular map I5 relating to hepatic artery blood flow side by side on the display screen IS2. The liver circular map I4 is assigned a color value according to the portal vein blood flow and is displayed in a color according to the color value. The liver circular map I5 is assigned a color value according to the hepatic artery blood flow and is displayed in a color according to the color value. A color bar I6 is displayed next to the liver circular map I4. The color bar I6 indicates the correspondence between the portal vein blood flow and the color value or color, and the color bar I7 indicates the correspondence between the hepatic artery blood flow and the color value or color.

By displaying the liver circular map I4 and the liver circular map I5 side by side, the user can grasp the portal vein blood flow and hepatic artery blood flow throughout the liver at a glance.

Note that, as shown in FIG. 23, the processing circuit 11 may display only one of the liver circular map I4 and the liver circular map I5. In this case, the processing circuit 11 may switch between the liver circular map I4 and the liver circular map I5 according to a switching instruction input via the input interface 14. Specifically, when the user operates the cursor 81 to click on the liver circular map I4, the processing circuit 11 switches the display object from the liver circular map I4 to the liver circular map I5. At this time, the processing circuit 11 may display the liver circular map I4 and the liver circular map I5 at the same position on the screen of the display device 13. This switching display also allows the user to grasp the portal vein blood flow rate and the hepatic artery blood flow rate of the entire liver at a glance. In addition, the switching display makes it easy to grasp the portal vein blood flow rate and the hepatic artery blood flow rate at the same position.

(Display example 3)
The processing circuit 11 according to the display example 3 displays a single circular liver map based on at least two feature data items, that is, the portal vein blood flow rate, the arterial blood flow rate, the ratio, and the fat mass. The circular liver map according to the display example 3 is displayed in a mixed color of two colors corresponding to the two feature data items, respectively.

24 is a diagram showing an example of a display screen IS3 according to display example 3. As shown in FIG. 24, the processing circuit 11 displays a single liver circular map I8 relating to the portal vein blood flow rate and the hepatic artery blood flow rate on the display screen IS3. A color bar I6 relating to the portal vein blood flow rate and a color bar I7 relating to the hepatic artery blood flow rate are displayed near the liver circular map I8. The liver circular map I8 is assigned a color value according to the portal vein blood flow rate, a color value according to the hepatic artery blood flow rate, and a color value based on both color values (hereinafter referred to as a mixed color value), and is displayed in a color according to the mixed color value. In other words, the liver circular map I8 is displayed in a mixed color of the color according to the portal vein blood flow rate and the color according to the hepatic artery blood flow rate. The user can grasp both the portal vein blood flow rate and the hepatic artery blood flow rate simply by observing the single liver circular map I8.

At this time, the processing circuit 11 may present the portal vein blood flow rate and the hepatic artery blood flow rate at the attention point on the liver circular map I8 to the user. For example, as shown in FIG. 25, when the attention point is specified by the cursor 81, the processing circuit 11 identifies the portal vein blood flow rate and the hepatic artery blood flow rate assigned to the specified attention point, and displays a window I9 including the numerical values of the portal vein blood flow rate and the hepatic artery blood flow rate. For example, the window I9 displays portal vein: 80%, artery: 20%, etc. This allows the user to quantitatively and accurately grasp the portal vein blood flow rate and the hepatic artery blood flow rate at the attention point. Also, as shown in FIG. 25, when the attention point is specified by the cursor 81, the processing circuit 11 may identify the portal vein blood flow rate and the hepatic artery blood flow rate assigned to the specified attention point, and display a cursor I10 indicating a position on the color bar I6 that corresponds to the identified portal vein blood flow rate and a cursor I11 indicating a position on the color bar I7 that corresponds to the identified hepatic artery blood flow rate. This method also allows the user to quantitatively and accurately grasp the portal vein blood flow and hepatic artery blood flow at the point of interest.

26, the processing circuitry 11 may display the liver circular map I8 and the axial slice image I12 of the subject's liver side by side. The axial slice image I12 may be generated by the processing circuitry 11 based on the time-series contrast volume data. For example, the processing circuitry 11 generates the axial slice image I12 by performing MPR processing on volume data of an arbitrary time phase among the time-series contrast volume data. As shown in FIG. 26, when a point of interest on the liver circular map I8 is specified by the cursor 81, the processing circuitry 11 identifies a corresponding pixel on the axial slice image I12 that anatomically corresponds to the specified point of interest, as shown in FIG. 26, and emphasizes the identified corresponding pixel. For example, the corresponding pixel may be emphasized by displaying a cursor I13 pointing to the corresponding pixel on the axial slice image I12. Note that the emphasis method is not limited to this, and for example, the corresponding pixel may be colored in a specific color, a mark may be added to the corresponding pixel, or a visual effect such as blinking may be added.

Conversely, when a point of interest on the axial slice image I12 is specified by the cursor 81, a corresponding pixel on the liver circular map I8 that anatomically corresponds to the specified point of interest may be identified, and the identified corresponding pixel may be emphasized. Furthermore, the images displayed side by side on the liver circular map I8 are not limited to axial slice images, but may be any CT image generated by applying three-dimensional image processing to time-series contrast volume data, such as sagittal slice images, coronal slice images, oblique slice images, and volume rendering images.

(Display example 4)
The processing circuitry 11 according to the display example 4 superimposes various anatomical information of the subject obtained based on the time-series contrast volume data onto the circular liver map. Examples of the anatomical information to be superimposed include the positions of blood vessels and tumors contained in the liver. The circular liver map according to the display example 4 may be a projection of any of the feature quantities of the portal vein blood flow, the hepatic artery blood flow, and the portal vein/hepatic artery blood flow ratio.

As shown in FIG. 27, the processing circuit 11 may display the vascular position I15 superimposed on the liver circular map I14. The method of superimposing the vascular position I15 is performed, for example, as follows. First, the processing circuit 11 extracts a vascular region of interest from the time-series contrast volume data by image processing or the like. The vascular region of interest may be the entire portal vein region and the hepatic artery region, or a part of the portal vein region and the hepatic artery region. Next, the processing circuit 11 projects the extracted vascular region onto the liver circular map I14 based on the correspondence (coordinate transformation formula) between pixels of the liver segment and the liver circular map. More specifically, the processing circuit 11 sets a plurality of sample points that are discretely arranged on the core line of the extracted vascular region, and applies a coordinate transformation formula to the plurality of sample points to project them onto the liver circular map I14. At this time, the processing circuit 11 identifies the liver segment to which the sample point to be projected belongs, and applies the coordinate transformation formula corresponding to the identified liver segment to the sample point. The processing circuitry 11 then forms a blood vessel position I15 on the liver circular map I14 by connecting the multiple sample points projected onto the liver circular map I14 with straight lines or the like. The processing circuitry 11 displays the blood vessel position I15 in a specific color, such as blue or red, superimposed on the liver circular map I14. The processing circuitry 11 may also calculate a liver blood flow parameter value for each pixel of the blood vessel position I15 and display each pixel in a color corresponding to the blood flow parameter value.

When the liver circular map I14 is a liver circular map relating to portal vein blood flow, the portal vein position may be superimposed on the liver circular map I14, or a combination of the portal vein position and the hepatic artery position may be superimposed, or the hepatic artery position may be superimposed. Similarly, when the liver circular map I14 is a liver circular map relating to hepatic artery blood flow or portal vein/hepatic artery blood flow ratio, the portal vein position may be superimposed, or a combination of the portal vein position and the hepatic artery position may be superimposed, or the hepatic artery position may be superimposed. Each time a switching command is issued by the user via the input interface 14, the processing circuit 11 may cyclically switch the vascular positions to be superimposed in the order of the portal vein position, the combination of the portal vein position and the hepatic artery position, the hepatic artery position, etc.

In this way, by superimposing the vascular positions on the circular liver map, it is possible to easily and comprehensively grasp the positional relationship between the hepatic blood flow parameters distributed throughout the liver and the hepatic blood vessels.

As shown in FIG. 28, the processing circuit 11 may project the tumor position I16 onto the liver circular map I14 in addition to the blood vessel position I15. The tumor position I16 can also be extracted and projected in the same manner as the blood vessel position I15. For example, the processing circuit 11 first extracts a tumor region of interest from the time-series contrast volume data by image processing or the like. Next, the processing circuit 11 projects the extracted tumor region onto the liver circular map I14 based on the correspondence (coordinate transformation formula) between the pixels of the liver section and the liver circular map. More specifically, the processing circuit 11 sets a plurality of sample points that are discretely arranged on the contour of the extracted tumor region, and applies a coordinate transformation formula to the plurality of sample points to project them onto the liver circular map I4. At this time, the processing circuit 11 identifies the liver section to which the tumor region to be projected belongs, and applies the coordinate transformation formula corresponding to the identified liver section to each sample point on the tumor region. The processing circuitry 11 then forms a tumor position I16 on the liver circular map I14 by connecting the multiple sample points projected onto the liver circular map I14 with straight lines or the like. The tumor position I16 may be superimposed on the liver circular map I14 and displayed in a specific color such as red or black, or may be displayed for each pixel in a color corresponding to the liver blood flow parameter value or CT value.

In this way, by superimposing the positions of blood vessels and tumors on the circular liver map, the positional relationship between the tumor and blood vessels, and the positional relationship between the liver and tumor can be easily understood.

The processing circuitry 11 may project, as the tumor position I16, a tumor region extracted from volume data collected by another nuclear medicine diagnostic device such as a PET device or a SPECT device onto the liver circular map I14. In this case, the processing circuitry 11 may align the volume data collected by the nuclear medicine diagnostic device with the time-series contrast volume data collected by the X-ray computed tomography device, and then apply a coordinate transformation formula corresponding to the liver segment to which the tumor region belongs to the tumor region and project it. This allows the processing circuitry 11 to display the tumor region in a color corresponding to the degree of accumulation of the radiopharmaceutical derived from the nuclear medicine diagnostic device.

In order to make it easier to grasp the blood vessels connected to the tumor, the processing circuit 11 may display the blood vessel positions of blood vessels connected to the tumor in a color different from the blood vessel positions of blood vessels not connected to the tumor. Furthermore, the processing circuit 11 may superimpose only the tumor position without superimposing both the tumor position and the blood vessel position. In this case, the processing circuit 11 may cyclically switch the superimposition target in the order of the blood vessel position, a combination of the blood vessel position and the tumor position, and the tumor position each time a switching instruction is given by the user via the input interface 14. Furthermore, the processing circuit 11 may superimpose any lesion position occurring in the liver, not limited to the tumor position, on the liver circular map.

(Display example 5)
The processing circuitry 11 according to the display example 5 displays a plurality of liver circular maps relating to a plurality of examination time points in chronological order. In this case, the processing circuitry 11 displays the liver circular map of the current examination and the liver circular map of the previous examination in chronological order, or displays the liver circular map of the current examination and the liver circular map of the previous examination by switching them according to a user instruction. Hereinafter, an example will be described in which progress observation is performed while performing radiation therapy, anticancer drug therapy, or gene therapy for liver cancer.

As shown in FIG. 29, the processing circuit 11 displays multiple circular liver maps relating to multiple examination time points in chronological order on the display screen IS4. A circular liver map I17 relating to the examination one year ago, a circular liver map I18 relating to the examination six months ago, and a circular liver map I19 relating to today's examination are displayed side by side. Tumor position I20 and tumor position I21 are superimposed on the circular liver map I17 relating to the examination one year ago and the circular liver map I18 relating to the examination six months ago, respectively. As the tumor shrinks over time, the tumor positions I20 and I21 shrink. Furthermore, the tumor has disappeared in today's examination, and as a result, there is no tumor area in the circular liver map I17.

By displaying multiple circular liver maps from multiple examination points in time in chronological order, it is possible to easily and comprehensively grasp changes in blood flow throughout the entire liver as the tumor shrinks. This makes it possible to visually grasp the process by which blood flow in the tumor area and its surrounding areas returns to portal vein dominance.

Note that multiple liver circular maps relating to multiple examination time points are not limited to being displayed side-by-side. For example, the processing circuitry 11 may display multiple liver circular maps relating to multiple examination time points one by one while switching between them in sequence. In this case, the processing circuitry 11 may display the liver circular maps to be displayed by switching between them in chronological order each time a switching instruction is given by the user via the input interface 14.

(Display example 6)
The processing circuitry 11 according to the display example 6 displays a single circular liver map based on at least two feature data items, that is, the portal vein blood flow rate, the arterial blood flow rate, the ratio, and the fat mass. The circular liver map according to the display example 6 displays the above two feature data items in different sections within the single circular liver map.

Figure 30 is a diagram showing an example of a display screen according to display example 6. As shown in Figure 30, the processing circuitry 11 displays a liver circular map I22 on the display screen IS5, in which the portal vein blood flow rate and the hepatic artery blood flow rate are separated in terms of location and projected onto one circular template. Each display section S1-S7 of the liver circular map I22 is radially divided into an outer peripheral subsection I23 and an inner peripheral subsection I24. For example, the subsection I23 is assigned to the portal vein blood flow rate, and the subsection I24 is assigned to the hepatic artery blood flow rate. The processing circuitry 11 individually associates pixels with liver segments for each of the subsections I23 and I24. Based on the association, the processing circuitry 11 projects the portal vein blood flow rate onto the subsection I23, and the hepatic artery blood flow rate onto the subsection I24. Each pixel in subsection I23 is displayed in a color according to color bar I6, which represents portal vein blood flow, and each pixel in subsection I24 is displayed in a color according to color bar I7, which represents hepatic artery blood flow.

By displaying the liver circular map I22, the user can check the portal vein blood flow and the hepatic artery blood flow separately on a single liver circular map.

The hepatic artery blood flow rate may be assigned to the outer subsection I23, and the hepatic artery blood flow rate may be assigned to the inner subsection I24. The feature values assigned to the subsections I23 and I24 are not limited to the portal vein blood flow rate and the hepatic artery blood flow rate, but may be the portal vein blood flow rate and the portal vein/hepatic artery blood flow ratio, or the hepatic artery blood flow rate and the portal vein/hepatic artery blood flow ratio. Each display section is not limited to being divided into two, but may be divided into three. In this case, the portal vein blood flow rate may be projected onto the first subsection, the hepatic artery blood flow rate onto the second subsection, and the portal vein/hepatic artery blood flow ratio onto the third subsection. The display section is not limited to being divided in the radial direction, but may be divided in any direction, such as the circumferential direction or the diagonal direction. It is also not limited to being divided in one direction, but may be divided in any arbitrary manner, such as a grid pattern.

(Display example 7)
The processing circuit 11 according to the seventh display example displays a circular liver map in which a display section corresponding to a resected liver segment among a plurality of liver segments of the liver is highlighted. In the following description, it is assumed, as an example, that the liver segment S7 has been resected in order to remove a tumor present in the liver segment S7.

As shown in FIG. 31, in the pre-resection circular liver map I26, a tumor position I27 is superimposed on a display section S7 corresponding to the liver segment S7. When the liver segment S7 is resected, the processing circuit 11 displays a circular liver map I28 in which the display section S7 corresponding to the resected liver segment S7 is missing. Any feature value, such as portal vein blood flow, hepatic artery blood flow, or portal vein/hepatic artery blood flow ratio, may be projected onto the circular liver map I8. The fact that the display section S7 is missing may be manually input via the input interface 14, or may be recognized by image processing.

When inputting manually, the user inputs information that the liver segment S7 has been resected via the input interface 14. When this information is input, the processing circuit 11 deletes the display section S7 from the pre-resection template and projects the feature data onto the post-resection template. This generates a post-resection circular liver map I28.

When performing recognition by image processing, the processing circuitry 11 extracts the liver region from the time-series contrast volume data of the subject after resection, and divides the liver region into liver segments S1-S8. At this time, the processing circuitry 11 recognizes that liver segment S7 has been resected because the liver region does not include liver segment S7. The processing circuitry 11 then deletes the display section S7 from the pre-resection template, and projects the feature data onto the post-resection template. This generates a post-resection circular liver map I28.

As shown in FIG. 31, a circular liver map I28 is displayed in which the display area corresponding to the resected liver segment is missing, allowing the user to recognize the resected liver segment in the circular liver map I28.

As shown in FIG. 32, the processing circuit 11 may display another post-resection liver circular map I29. The liver circular map I29 does not lack a display section S7 corresponding to the resected liver segment S7, and includes all display sections S1-S8. The display sections S1-S6, S8 of the liver circular map I29 corresponding to the unresected liver segments S1-S6, S8, respectively, are displayed in a color corresponding to the assigned feature value, and the display section S7 corresponding to the resected liver segment S7 is displayed, for example, colorless, since no feature value is assigned to it. Since the display section S7 corresponding to the resected liver segment S7 is not displayed in color, the user can recognize the resected liver segment S7 in the liver circular map I28.

As shown in FIG. 33, the processing circuit 11 may display another post-resection liver circular map I30. In the liver circular map I30, a display section S7 corresponding to the resected liver segment S7 is drawn in dotted lines. Since no feature value is assigned to the display section S7, it is displayed in no color. In this way, since the display section S7 corresponding to the resected liver segment S7 is displayed in dotted lines, the user can recognize the resected liver segment S7 in the liver circular map I28.

The display area corresponding to the resected liver segment is not limited to being drawn with a dotted line, and may be displayed in any manner as long as it is visually distinguishable from the display area corresponding to the non-resected liver segment. For example, the processing circuit 11 may display the display area corresponding to the resected liver segment in a color different from the display area corresponding to the non-resected liver segment.

As shown in FIG. 34, the processing circuitry 11 may display another post-resection liver circular map I31. The liver circular map I31 is formed in a circular shape by display sections S1-S6, S8 corresponding to the remaining liver segments S1-S6, S8 excluding the liver segment S7. For example, the processing circuitry 11 determines the arrangement of the display sections S2, S3, and S6 in the outer region based on the sizes of the remaining liver segments S2, S3, and S6 included in the outer region to which the resected liver segment S7 belonged. This generates a post-resection template. The liver segments S2, S3, and S6 can be obtained by dividing the liver region included in the post-resection time-series contrast volume data into liver segments. The processing circuitry 11 can then generate the liver circular map I31 by projecting feature data based on the post-resection time-series contrast volume data onto the post-resection template.

The processing circuitry 11 may generate the liver circular map I31 by newly performing the process shown in FIG. 15 etc. on the time-series contrast volume data after resection. That is, the processing circuitry 11 extracts the liver region, portal vein region, and hepatic artery region from the time-series contrast volume data after resection, and divides the liver region into multiple liver segments S1-S6, S8. Next, the processing circuitry 11 calculates the distance and direction between each liver segment S1-S6, S8 and a reference position, and calculates the size of each liver segment S1-S6, S8. Next, the processing circuitry 11 determines the arrangement of the display sections S1-S6, S8 in the template based on the calculated distance, direction, and size, and reconstructs the template. Then, the processing circuitry 11 projects the feature data onto the reconstructed template to generate the liver circular map I31.

As shown in Figure 34, in the liver circular map I31, the remaining display sections S1-S6 and S8 can be allocated relatively large areas, making it possible to grasp in detail the spatial distribution of blood flow parameters in the remaining liver segments S1-S6 and S8.

(Display example 8)
The resected liver regenerates. The processing circuit 11 according to the eighth display example displays the degree of liver regeneration together with the circular liver map. In the following description, it is assumed that a liver segment S7 has been resected and is in the process of regeneration.

Figure 35 is a diagram showing an example of a display screen IS6 according to display example 8. As shown in Figure 35, the processing circuit 11 displays a liver circular map I32 relating to the regenerating liver and a window I33 for the regeneration ratio side by side on the display screen IS6. The liver circular map I32 is generated based on time-series contrast volume data relating to a patient whose liver is being regenerated. Specifically, the processing circuit 11 extracts a liver region from the time-series contrast volume data relating to the patient whose liver is being regenerated, and divides the liver region into a plurality of liver segments S1-S8. The regenerating liver partial region is also divided as a liver segment S7. Next, the processing circuit 11 calculates the distance and direction between each liver segment S1-S8 and the reference position. Next, the processing circuit 11 determines the arrangement of the display segments S1-S8 in the template based on the calculated distance and direction, and reconstructs the template. The area and arrangement of the display segments may be determined based on the liver segments S1-S8 before resection in order to improve the visibility of the display segments corresponding to the regenerating liver segments. The area of the display section may be determined uniformly or arbitrarily in advance, as in the first and second generation methods. The processing circuitry 11 then projects the feature data onto the template to generate the liver circular map I32.

As shown in FIG. 35, in the display section S7 of the liver circular map I32, only pixels that correspond to the parts where liver tissue exists and blood flow due to regeneration are assigned feature values and displayed in a color corresponding to the feature value. Pixels that correspond to parts that have not yet regenerated, do not have liver tissue, and do not have blood flow are not assigned feature values and are therefore displayed colorless. Note that these pixels may not be colorless, but may be displayed in a color associated with the lack of regeneration (e.g., gray). This makes it possible to grasp the spatial distribution of blood flow parameters of the liver segment S7 that is in the process of regeneration.

As shown in FIG. 35, the regeneration ratio is displayed in window I33. The regeneration ratio is defined as the ratio of the current volume to the volume before resection. The processing circuit 11 calculates the volume of the liver segment S7 before resection and the current volume of the liver segment S7, calculates the ratio of the volume of the liver segment S7 before resection to the current volume of the liver segment S7, and displays this ratio as the regeneration ratio. For example, as shown in FIG. 35, if the regeneration ratio of the liver segment S7 is 25%, it is displayed as "S7" and "regeneration ratio: 25%". By displaying window I33, the user can know the regeneration ratio of the resected liver segment.

(Variation 1)
In the above various embodiments, the liver unfolded map is a circular liver map in which the display sections S1-S8 in the shape of an annulus or sector shape representing the liver segments S1-S8 are arranged on a two-dimensional circular template with the reference position such as the hepatic portal area as the center point. However, the liver unfolded map of the present embodiment is not limited to this. For example, the liver unfolded map may be a map in which the display sections S1-S8 in the shape of a rectangle representing the liver segments S1-S8 are arranged on a two-dimensional rectangular template with the reference position such as the hepatic portal area as the center point. Also, as shown in FIG. 36, the liver unfolded map I34 may be a map in which the display sections S1-S8 in the shape of a mimicking the liver segments S1-S8 are arranged on a two-dimensional plane. The reference position P0 is drawn on the liver unfolded map I34, and a figure such as an arrow representing the blood flow path from the hepatic portal area, which is the reference position P0, to each display section S1-S8 is drawn. Since the feature amount data is also projected on the display sections S1-S8 in the liver unfolded map I34, each pixel of the display sections S1-S8 is displayed in a color according to the feature amount.

(Variation 2)
In the above various examples, the feature amount projected on the display section is a blood flow parameter calculated by a CT perfusion test. However, this embodiment is not limited to this. As described above, the feature amount may be fat mass. The fat mass can be calculated based on the CT value. The processing circuit 11 calculates the fat mass for each pixel of the liver section based on the CT value, and assigns the fat mass to the corresponding pixel of the display section. This generates a liver unfolded map related to the fat mass. The processing circuit 11 holds a color table in which the fat mass and the color value are associated. The processing circuit 11 can display the liver unfolded map in a color corresponding to the fat mass by referring to the color table. Note that the feature amount is not limited to the blood flow parameter or fat mass, and may be a CT value or another analysis parameter.

(Variation 3)
In the various embodiments described above, the medical image processing apparatus 1 is a computer separate from the medical image diagnostic apparatus 2. However, the present embodiment is not limited to this. The medical image processing apparatus 1 may be a computer incorporated in the medical image diagnostic apparatus 2.

According to at least one of the embodiments described above, it is possible to grasp characteristic quantities such as the arterial/portal blood flow ratio of the entire liver in a short period of time.

The term "processor" used in the above description means a circuit such as a CPU, a GPU, or an application specific integrated circuit (ASIC), a programmable logic device (e.g., a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA)). The processor realizes its function by reading and executing a program stored in a memory circuit. Note that instead of storing a program in a memory circuit, the processor may be configured to directly incorporate the program into its circuit. In this case, the processor realizes its function by reading and executing a program incorporated in the circuit. Also, instead of executing a program, a function corresponding to the program may be realized by a combination of logic circuits. Note that each processor in this embodiment is not limited to being configured as a single circuit for each processor, but may be configured as a single processor by combining multiple independent circuits to realize its function. Furthermore, the multiple components in FIG. 1 and FIG. 2 may be integrated into a single processor to realize its function.

Although several embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations of embodiments can be made without departing from the spirit of the invention. These embodiments and their modifications are within the scope of the invention and its equivalents as set forth in the claims, as well as the scope and spirit of the invention.

REFERENCE SIGNS LIST 1 Medical image processing device 2 Medical image diagnostic device 3 Medical image storage device 11 Processing circuit 12 Communication interface 13 Display device 14 Input interface 15 Storage device 111 Image processing function 112 Feature amount acquisition function 113 Map generation function 114 Display control function

Claims (18)

a division unit that divides a liver region included in the liver volume data into a plurality of liver segments based on the vascular course of the portal vein region and/or the hepatic artery region;
an acquisition unit that acquires feature amount data related to feature amounts of the liver based on the volume data;
a unit for generating a map by projecting the feature amount data onto a two-dimensional development having a plurality of display sections respectively corresponding to the plurality of liver segments, the unit generating a development in which the plurality of display sections respectively corresponding to the plurality of liver segments are arranged with a reference position of the portal vein region as a center point, and generating the map by projecting the feature amount data onto the development;
A display control unit that displays the map;
A medical image processing device comprising: The medical image processing device according to claim 1, wherein the generating unit uses the hepatic portal region of the liver as the reference position. The medical image processing device according to claim 1 or 2, wherein the generating unit determines the arrangement of the multiple display sections in the developed view based on the distance and/or direction between the reference position and the multiple liver segments in the volume data. The medical image processing device according to any one of claims 1 to 3, wherein the generating unit determines the size of each of the plurality of display sections in the developed view based on the size of each of the plurality of liver segments in the volume data. The medical image processing device according to any one of claims 1 to 4, wherein the feature data includes at least one of portal vein blood flow, arterial blood flow, a ratio of portal vein blood flow to arterial blood flow, and fat mass. The medical image processing device according to claim 5, wherein the display control unit displays two maps based on at least two of the feature data, portal vein blood flow, arterial blood flow, the ratio of portal vein blood flow to arterial blood flow, and fat mass, side by side. The medical image processing device according to claim 5, wherein the display control unit displays a single map based on at least two of the feature data, the portal vein blood flow rate, the arterial blood flow rate, the ratio, and the fat mass. The medical image processing device according to any one of claims 1 to 7, wherein the display control unit displays the map on which the location of the liver tumor is superimposed. The medical image processing device according to any one of claims 1 to 8, wherein the display control unit displays the map on which the positions of blood vessels in the liver are superimposed. The medical image processing device according to any one of claims 1 to 9, wherein the display control unit displays the map in which a display section corresponding to a resected liver segment among the plurality of liver segments is highlighted. The medical image processing device according to any one of claims 1 to 10, wherein the display control unit displays the map of the current examination and the map of the past examination in chronological order, or switches between the map of the current examination and the map of the past examination according to a user instruction. The medical image processing device according to any one of claims 1 to 11, wherein the display control unit displays the map with color values corresponding to the feature values, and displays a color bar next to the map indicating the correspondence between the feature values and the color values. The medical image processing device according to claim 12, wherein the display control unit, when a point of interest on the map is specified, displays the characteristic amount of the point of interest as a numerical value and/or displays an arrow indicating the position of the color bar corresponding to the characteristic amount of the point of interest. The medical image processing device according to claim 12, wherein the display control unit displays the map and a display image based on the volume data, and when a first attention point is specified in the map, the display control unit emphasizes a position in the display image corresponding to the first attention point, and when a second attention point is specified in the display image, the display control unit emphasizes a position in the map corresponding to the second attention point. The medical image processing device according to claim 1, wherein the generating unit determines the distance and/or direction between the reference position and each of the plurality of liver segments, and generates the developed view in which the plurality of display sections are allocated in a circular shape according to the distance and/or direction centered on the reference position. The medical image processing device according to claim 15, wherein the generating unit divides the plurality of liver segments into an inner liver segment and an outer liver segment based on the distance and a threshold value, arranges a display segment corresponding to the inner liver segment among the plurality of display segments in the inner region of the two regions obtained by dividing the developed view in the radial direction, and arranges a display segment corresponding to the outer liver segment among the plurality of display segments in the outer region. 17. The medical image processing device of claim 15, wherein the generation unit unfolds each of the plurality of liver segments along a cross section corresponding to the running direction of the portal vein region connected to the liver segment, corresponds each first pixel of the cross section in the unfolded liver segment to each second pixel of a display section corresponding to the liver segment, and assigns a projection value along a projection line perpendicular to the cross section, passing through the first pixel, and penetrating the unfolded liver segment to the second pixel of the display section. an imaging unit that performs medical imaging on the liver of a subject and collects raw data;
a reconstruction unit for reconstructing volume data based on the raw data;
a division unit that divides a liver region included in the volume data into a plurality of liver segments based on a blood vessel course of a portal vein region and/or a hepatic artery region;
an acquisition unit that acquires feature amount data related to feature amounts of the liver based on the volume data;
a unit for generating a map by projecting the feature amount data onto a two-dimensional development having a plurality of display sections corresponding to a plurality of hepatic segments determined based on the vascular course of the liver, the unit generating a development in which the plurality of display sections corresponding to the plurality of hepatic segments are arranged with a reference position of the portal vein region as a center point, and generating the map by projecting the feature amount data onto the development;
A display control unit that displays the map;
A medical image diagnostic apparatus comprising: