Medical image processing apparatus, medical image processing method, and program

Abstract

To enable a symptom to be accurately evaluated.SOLUTION: A medical image processing apparatus according to an embodiment includes an acquiring part, a derivation part, and an analysis part. The acquiring part acquires a medical image of a plurality of time phases of the brain with one of the right-left brain of a patient as an affected part and the other as an unaffected part. The derivation part derives a feature amount of a collateral blood circulation in the brain of the patient. The analysis part analyses a delay in the time phase on the affected part with respect to the unaffected part based on the comparison result of the feature amount on the affected and the unaffected parts per the plurality of time phases.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The embodiments disclosed in this specification and the drawings relate to a medical image processing device, a medical image processing method, and a program. [Background technology]

[0002] One technique for diagnosing cerebral infarction is to quantitatively measure the status of collateral circulation by analyzing CT (Computed Tomography) images. This technique calculates quantitative indices of collateral circulation from the vascular distribution area and region of interest analyzed using 4D-CTA (CT Angiography), and uses the calculated quantitative indices to diagnose cerebral infarction. Collateral circulation is a type of circulatory vessel that is newly generated to compensate for the deterioration of blood flow when stenosis or blockage occurs.

[0003] Alternatively, there is a technique that divides the entire brain into hemispheres and uses CT images of the side with cerebral infarction symptoms (hereafter referred to as the affected side) and the side without symptoms (hereafter referred to as the healthy side).This technique counts the number of pixels in the area filled with blood vessels on both the affected and healthy sides, and calculates the ratio of the total amount of blood vessel filling on the affected and healthy sides (hereafter referred to as the left-right ratio), which is used as a quantitative index of collateral circulation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-51474 Summary of the Invention [Problem to be solved by the invention]

[0005] The advantage of 4D-CTA is that it allows for detailed analysis, including delays in blood flow arrival time. However, it has disadvantages, such as the need to take CT images about 20 times per minute, which increases the imaging time and the amount of radiation exposure during imaging.

[0006] In contrast, the technology for calculating the left-right ratio has the advantage that analysis can be performed with a single image capture.However, although it uses information on the proportion of blood vessels present, there is a difference in the time it takes for blood flow to reach the affected and healthy sides, which makes the analysis insufficient and makes it difficult to accurately evaluate conditions such as collateral circulation.

[0007] The problem to be solved by the embodiments disclosed in this specification and the drawings is to enable accurate evaluation of a medical condition. However, the problem to be solved by the embodiments disclosed in this specification and the drawings is 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. [Means for solving the problem]

[0008] A medical image processing apparatus according to an embodiment includes an acquisition unit, a derivation unit, and an analysis unit. The acquisition unit acquires medical images of a subject's brain at multiple time phases, with one of the two sides designated as an affected side and the other as a healthy side. The derivation unit derives features related to collateral blood circulation in the subject's brain based on the acquired original medical images. The analysis unit analyzes a delay in the time phase of the affected side relative to the healthy side based on a comparison result between the features of the affected side and the healthy side for each of the multiple time phases. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram showing an example of the configuration of a hospital system 1 according to a first embodiment. [Figure 2] FIG. 1 is a block diagram showing an example of the configuration of a medical image processing apparatus 100 according to a first embodiment. [Figure 3] 4 is a flowchart showing an example of processing in the medical image processing apparatus 100. [Figure 4] FIG. 10 is a diagram showing an example of time change in the integrated value of the number of blood vessel pixels on the affected side and the healthy side. [Figure 5] FIG. 10 is a diagram showing an example of time change in the integrated value of the number of blood vessel pixels on the affected side and the healthy side. [Figure 6]FIG. 10 is a diagram showing an example of time change in the integrated value of the number of blood vessel pixels on the affected side and the healthy side. [Figure 7] FIG. 10 is a diagram showing an example of a procedure for combining images from two time phases. [Figure 8] FIG. 10 is a diagram showing an example of an image of a procedure for combining images from one time phase and images from two time phases. [Figure 9] FIG. 10 is a block diagram showing an example of the configuration of a medical image processing apparatus 200 according to a second embodiment. [Figure 10] FIG. 10 is a diagram showing an example of time change in the integrated value of the number of blood vessel pixels on the affected side and the healthy side. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a medical image processing apparatus, a medical image processing method, and a program according to an embodiment will be described with reference to the drawings.

[0011] For patients with cerebral infarction, the presence of collateral circulation is an indicator of the possibility of tissue recovery, so its assessment is important. In clinical practice, for example, doctors visually assess the degree of development of collateral circulation from vascular images visualized by CTA (CT angiography) or MRA (magnetic resonance angiography), and use this information to make treatment decisions for patients.

[0012] Specifically, the state of collateral circulation is qualitatively evaluated by visually checking the proportion of blood vessels visible on the affected side compared to the healthy side, comparing the affected side where the infarction has occurred with the healthy side.In addition, the state of collateral circulation is qualitatively evaluated by visually checking the degree of delay in blood flow arrival on the affected side compared to the healthy side.

[0013] However, because these are qualitative evaluations, it is difficult for treating physicians to agree on a precise judgment. Therefore, the medical image processing device of the embodiment analyzes CT images to quantitatively measure the state of collateral circulation. Furthermore, the medical image processing device of the embodiment calculates the left-right ratio between the healthy side and the unhealthy side, taking into account the delay in blood flow arrival time (time phase delay), thereby enabling accurate evaluation of the condition of collateral circulation and other conditions.

[0014] (First embodiment)

[0015] 1 is a block diagram showing an example of the configuration of an in-hospital system 1 according to the first embodiment. The in-hospital system 1 according to the first embodiment includes, for example, a Hospital Information System (hereinafter, referred to as HIS) 10, a Radiology Information System (hereinafter, referred to as RIS) 20, a medical image diagnostic apparatus (modality) 30, a Picture Archiving and Communication System (PACS) 40, and a medical image processing apparatus 100.

[0016] The HIS 10 is a computer system that supports operations within a hospital. Specifically, the HIS 10 has various subsystems, such as an electronic medical record system, a medical accounting system, a medical appointment system, a hospital reception system, and an admission and discharge management system.

[0017] The HIS 10 is a computer system that supports operations within a hospital. Specifically, the HIS 10 has various subsystems, such as an electronic medical record system, a medical accounting system, a medical appointment system, a hospital reception system, and an admission and discharge management system.

[0018] The HIS 10 includes a computer such as a server device or a client terminal that includes a processor such as a CPU (Central Processing Unit), memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory), a display, an input interface, and a communication interface.

[0019] A user inputs and references patient information using an electronic medical record system included in the HIS 10. A user issues an order for an imaging examination to the HIS 10. The HIS 10 transfers order information corresponding to the imaging examination order to other systems such as the RIS 20.

[0020] The RIS 20 is a computer system that supports operations in the imaging diagnostic department. The RIS 20 manages reservations for imaging examination orders in cooperation with the HIS 10, as well as links reservation information to examination equipment and manages examination information. The RIS 20 includes, for example, a computer such as a server device or a client terminal that has a processor such as a CPU, memories such as ROM and RAM, a display, an input interface, and a communication interface.

[0021] The modality 30 performs imaging (photography) in accordance with imaging conditions (photography protocol) determined based on, for example, an imaging test instruction. Examples of the modality 30 include an X-ray computed tomography apparatus, an X-ray diagnostic apparatus, a magnetic resonance imaging apparatus, an ultrasound diagnostic apparatus, and a nuclear medicine diagnostic apparatus. The modality 30 generates medical images (medical original images) based on operations by a user such as a doctor (radiologist) or a diagnostic radiologist. In this embodiment, the modality 30 is a CT apparatus, and the medical original images are four-dimensional CT images obtained by dynamically imaging a subject. The generated four-dimensional CT images are transmitted to the PACS 40. The modality 30 is an example of a medical image generation apparatus.

[0022] The PACS 40 is a computer system that receives 4D CT images sent by the modality 30 and other medical images sent by external devices and stores them in a database. The PACS 40 transmits (transfers) medical images, such as 4D CT images, stored in the database in response to requests from clients. The PACS 40 includes a server computer that includes a processor such as a CPU, memory such as ROM and RAM, a display, an input interface, and a communication interface.

[0023] The configuration of the in-hospital system 1 is not limited to the above. The in-hospital system 1 may include, for example, an image interpretation report creation device. Also, some elements of the in-hospital system 1 may be integrated. For example, the HIS 10 and the RIS 20 may be integrated into one system.

[0024] The medical image processing device 100 is a device that provides information for a doctor to diagnose cerebral infarction in a subject by performing image processing on four-dimensional CT images of multiple time phases. The medical image processing device 100 generates a maximum intensity projection image (hereinafter referred to as an MIP image) by, for example, performing maximum intensity projection (MIP) processing on the four-dimensional CT image. The medical image processing device 100 generates an MIP image by, for example, specifying a projection processing range (hereinafter referred to as an MIP range) on the four-dimensional CT image and performing MIP processing on the MIP range.

[0025] 2 is a block diagram showing an example of the configuration of the medical image processing apparatus 100 of the first embodiment. The medical image processing apparatus 100 includes, for example, a communication interface 110, an input interface 120, a display 130, a processing circuit 140, and a memory 150. The communication interface 110, the input interface 120, and the display 130 in the medical image processing apparatus 100 are provided separately from the communication interface, the input interface, and the display provided in the HIS 10, but these may be common.

[0026] The communication interface 110 communicates with external devices such as the RIS 20, modality 30, and PACS 40 via a network NW such as a LAN (Local Area Network). The communication interface 110 includes a communication interface such as a NIC (Network Interface Card). The network NW may include the Internet, a cellular network, a Wi-Fi network, a WAN (Wide Area Network), etc. instead of or in addition to a LAN.

[0027] The input interface 120 accepts various input operations from a user such as a doctor, converts the accepted input operations into electrical signals, and outputs the electrical signals to the processing circuitry 140. For example, when a user performs an input operation, the input interface 120 generates information corresponding to the input operation. The input interface 120 outputs the generated information corresponding to the input operation to the processing circuitry 140.

[0028] The input interface 120 includes, for example, a mouse, a keyboard, a trackball, a switch, a button, a joystick, a touch panel, etc. The input interface 120 may be, for example, a user interface that accepts audio input from a microphone, etc. If the input interface 120 is a touch panel, the input interface 120 may also have the display function of the display 130.

[0029] In this specification, the input interface is not limited to an interface having physical operation parts such as a mouse, keyboard, etc. For example, an example of an input interface also includes an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device provided separately from the device and outputs this electrical signal to a control circuit.

[0030] The display 130 displays various types of information. For example, the display 130 displays an image generated by the processing circuit 140, a GUI (Graphical User Interface) for receiving various input operations from a user, etc. For example, the display 130 is an LCD (Liquid Crystal Display), a CRT (Cathode Ray Tube) display, an organic EL (Electro Luminescence) display, etc. The display 130 is an example of a display unit.

[0031] The processing circuitry 140 includes, for example, an acquisition function 141, an identification function 142, a generation function 143, a derivation function 144, an analysis function 145, and a display control function 146. The processing circuitry 140 realizes these functions by, for example, a hardware processor (computer) executing a program stored in a memory (storage circuitry) 150.

[0032] The hardware processor refers to a circuit such as a CPU, a graphics processing unit (GPU), an application specific integrated circuit (ASIC), a programmable logic device (e.g., a simple programmable logic device (SPLD) or a complex programmable logic device (CPLD)), or a field programmable gate array (FPGA).

[0033] Instead of storing the program in the memory 150, the program may be directly embedded in the circuit of the hardware processor. In this case, the hardware processor realizes its functions by reading and executing the program embedded in the circuit. The program may be stored in the memory 150 in advance, or may be stored in a non-transitory storage medium such as a DVD or CD-ROM, and installed into the memory 150 from the non-transitory storage medium when the non-transitory storage medium is inserted into a drive device (not shown) of the medical image processing apparatus 100.

[0034] The hardware processor is not limited to being configured as a single circuit, but may be configured as a single hardware processor by combining multiple independent circuits to realize each function. Furthermore, multiple components may be integrated into a single hardware processor to realize each function. The hardware processor, memory, etc. in the medical image processing device 100 are provided separately from the hardware processor, memory, etc. of the HIS 10, but they may be shared.

[0035] The memory 150 is realized by, for example, a semiconductor memory element such as RAM or flash memory, a hard disk, or an optical disk. These non-transitory storage media may also be realized by other storage devices connected via a communication network, such as a network-attached storage (NAS) or an external storage server device. The memory 150 may also include other non-transitory storage media, such as a read-only memory (ROM) or a register.

[0036] The acquisition function 141 acquires medical images of the brain at multiple time phases, with one of the left and right sides of the subject's brain designated as the affected side and the other as the healthy side. The acquisition function 141 is an example of an acquisition function. The acquisition function 141 acquires medical images provided by, for example, the modality 30 or the PACS 40. The acquisition function 141 is an example of an acquisition unit.

[0037] The identification function 142 identifies an MIP range in a four-dimensional CT image. For example, the identification function 142 identifies an MIP range on each of the affected side and the healthy side in the four-dimensional CT image acquired by the acquisition function 141. The identification function 142 identifies an MIP range based on information such as the location where an infarction is assumed to have occurred. The identification function 142 may use the entire brain as the MIP range, or may use a specific area in the brain as the MIP range.

[0038] The generation function 143 generates MIP images as medical images based on the four-dimensional CT image generated by the modality 30. For example, the generation function 143 generates an affected-side MIP image and an unaffected-side MIP image by performing MIP processing on the MIP ranges identified by the identification function 142 for each of the affected side and unaffected side of the four-dimensional CT image.

[0039] The generation function 143 generates an MIP image for each of the four-dimensional CT images of multiple time phases. The generation function 143 further generates a vascular image showing blood vessels including collateral circulation for each of the affected side and healthy side based on the generated MIP images. The generation function 143 is an example of a generation unit.

[0040] The derivation function 144 derives features related to collateral circulation in the subject's brain based on the MIP images generated by the generation function 143. The derivation function 144 calculates the total vascular filling volume on each of the affected and healthy sides of the brain, for example, by counting the number of pixels in areas filled with blood vessels (hereinafter referred to as the number of blood vessel pixels) in each MIP image of the affected and healthy sides of the brain. The derivation function 144 derives features based on the calculated total vascular filling volume. The derivation function 144 derives vascular features for multiple time phases. The derivation function 144 is an example of a derivation unit.

[0041] The analysis function 145 compares the feature amounts on the affected side and the healthy side for each of multiple time phases. The feature amounts include, for example, the left-right inflow ratio, the left-right presence ratio, and the left-right outflow ratio. The analysis function 145 analyzes the delay of the time phase of the affected side relative to the healthy side based on the result of comparing the feature amounts on the affected side and the healthy side. The analysis function 145 is an example of an analysis unit.

[0042] The left-right inflow ratio is the ratio of the amount of fluid (blood and contrast agent) that flows into blood vessels (including collateral circulation) on the affected side to that on the healthy side. The left-right presence ratio is the ratio of the amount of blood vessels that exist on the affected side to that on the healthy side. The left-right outflow ratio is the ratio of the amount of fluid that flows out of blood vessels on the affected side to that on the healthy side.

[0043] The analysis function 145 determines a phase delay of the affected side relative to the healthy side based on the relationship between a left-right ratio, such as a left-right inflow ratio, a left-right outflow ratio, or a left-right presence ratio, and a predetermined threshold. The analysis function 145 determines that a phase delay exists when, for example, the left-right inflow ratio is less than a first threshold. The analysis function 145 determines that a phase delay exists between different phases when, for example, the left-right presence ratio between different phases is less than a second threshold. The analysis function 145 determines that a phase delay exists when, for example, the left-right outflow ratio is equal to or greater than a third threshold. The analysis function 145 is an example of an analysis unit.

[0044] For example, the analysis function 145 may generate side-specific fluid volume information by comparing fluid volume information between different time phases on the affected side and the healthy side. The analysis function 145 may determine the delay in time phases related to the fluid volume on the affected side relative to the healthy side based on the comparison result between the side-specific fluid volume information on the affected side (hereinafter referred to as affected-side individual fluid volume information) and the side-specific fluid volume information on the healthy side (hereinafter referred to as healthy-side individual fluid volume information).

[0045] The display control function 146 displays various images on the display 130. The display control function 146 displays, for example, the four-dimensional CT image acquired by the acquisition function 141, the MIP image generated by the generation function 143, delay information related to the delay in time phase, such as the determination result in the analysis function 145, on the display 130. The display control function 146 is an example of a display control unit.

[0046] Next, a description will be given of processing in the medical image processing apparatus 100 of the first embodiment. Fig. 3 is a flowchart showing an example of processing in the medical image processing apparatus 100. First, the medical image processing apparatus 100 acquires, in the acquisition function 141, four-dimensional CT images of multiple time phases stored in the PACS 40 (step S101).

[0047] Next, the identification function 142 identifies MIP ranges for each of the affected side and healthy side of the multi-phase 4D CT images (step S103). In identifying the MIP range, the identification function 142 may, for example, determine the entire brain region (whole brain), the anterior cerebral artery region (ACA region), the middle cerebral artery region (MCA region), or the posterior cerebral artery region (PCA region) as the MIP range, or may determine multiple of these or other ranges as the MIP range.

[0048] Next, the generation function 143 performs MIP processing on the MIP range in the 4D CT image identified by the identification function 142 to generate an MIP image (step S105). The generation function 143 generates an MIP image in the MIP range of each of the affected side and healthy side in each of the 4D CT images of multiple time phases.

[0049] Next, the generation function 143 generates blood vessel images on the affected side and healthy side of the brain based on the generated MIP images (step S107). The generation function 143 also generates blood vessel images representing blood vessels within the MIP range on each of the affected side and healthy side in each of the MIP images of multiple time phases.

[0050] Next, the derivation function 144 and the analysis function 145 analyze the left-right ratio of the affected side and the healthy side (step S109). In analyzing the left-right ratio, the derivation function 144 derives feature amounts for each of the affected side and the healthy side based on the MIP image generated by the generation function 143. The derivation function 144 derives, for example, any of the left-right inflow ratio, the left-right existence ratio, and the left-right outflow ratio as the feature amount. The analysis of the left-right inflow ratio, the left-right existence ratio, and the left-right outflow ratio will be described below.

[0051] The derivation function 144 calculates the left / right inflow ratio Output(1) at a specific timing by substituting the number of blood vessel pixels at multiple time phases into the following equation (1). The number of pixels ya1 in equation (1) is the number of blood vessel pixels on the affected side at time t1, and represents the total filling volume of blood vessels in the affected-side hemisphere at time t1. The number of pixels ya1 can be expressed, for example, by the following equation (2). Figure 4 shows a graph of the change over time in the integrated value of the number of blood vessel pixels on the affected side and the healthy side. Figure 4 is a diagram showing an example of the change over time in the integrated value of the number of blood vessel pixels on the affected side and the healthy side.

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[0052] Alternatively, the derivation function 144 calculates the left / right presence ratio Output(2) at a specific timing by substituting the number of blood vessel pixels in multiple time phases into the following equation (3). The change over time in the integrated value of the number of blood vessel pixels on the affected side and the healthy side at this time is shown in a graph in Figure 5. Figure 5 is a diagram showing an example of the change over time in the integrated value of the number of blood vessel pixels on the affected side and the healthy side.

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[0053] Alternatively, the derivation function 144 calculates the left-right outflow ratio Output(3) for multiple time phases by substituting the number of blood vessel pixels for multiple time phases into the following equation (4). The change over time in the integrated value of the number of blood vessel pixels for each of the affected and healthy sides is shown in a graph in Figure 6. Figure 6 is a diagram showing an example of the change over time in the integrated value of the number of blood vessel pixels for each of the affected and healthy sides.

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[0054] Next, the analysis function 145 analyzes the time phase delay of the affected side relative to the healthy side based on the left-right ratio derived by the derivation function 144. For example, when the derivation function 144 derives the left-right inflow ratio Output(1), the analysis function 145 compares the left-right inflow ratio Output(1) with a first threshold value (here, 0.5). The analysis function 145 determines that there is no time phase delay when Output(1)≧0.5, and determines that there is a time phase delay when Output(1)<0.5. The first threshold value may be a number other than "0.5."

[0055] For example, when the derivation function 144 derives the left-right presence ratio Output(2), the analysis function 145 compares the left-right presence ratio Output(2) with a second threshold (here, 0.5). Here, the left-right presence ratio Output(2) compares whether or not there is a delay between the first time phase (= t1) and the third time phase (= t3). When Output(2) ≧ 0.5, the analysis function 145 determines that there is no phase delay (α phase delay) between the first time phase (= t1) and the third time phase (= t3) being compared, and when Output(2) < 0.5, it determines that there is a phase delay. The second threshold may be a value other than "0.5." The second threshold is the same as the first threshold, but may be different from the first threshold.

[0056] For example, when the derivation function 144 derives the left-right outflow ratio Output(3), the analysis function 145 compares the left-right outflow ratio Output(3) with a third threshold (here, 0.5). When Output(3) ≧ 0.5, the analysis function 145 determines that the amount of fluid outflow from the collateral circulation between multiple time phases is equal between the affected side and the healthy side, and that there is no phase delay. When Output(3) < 0.5, the analysis function 145 determines that the amount of fluid outflow from the collateral circulation between multiple time phases is less on the affected side than on the healthy side, and that there is a phase delay. The third threshold may be a value other than "0.5." The third threshold is the same as the first threshold, but the second threshold may be different from the first threshold.

[0057] Once the analysis function 145 has completed the left-right ratio analysis, the display control function 146 displays the MIP image, blood vessel image, analysis results, etc. on the display 130. The display control function 146 displays the MIP image, blood vessel image, and analysis results as appropriate, and some or all of them may not be displayed.

[0058] The generation function 143 may, for example, generate a combined MIP image of the nth time phase and the (n+α)th time phase, and the display control function 146 may display the generated combined MIP image on the display 130. FIG. 7 is a diagram showing an example of an image of a procedure for combining images for two time phases. The generation function 143 may, for example, generate a combined MIP image TimeMIP(t1, t2) by combining an MIP image of a first time phase (=t1) and an MIP image of a second time phase (=t2), and the display control function 146 may display the generated combined MIP image TimeMIP(t1, t2) on the display 130.

[0059] Similarly, the generation function 143 may generate a combined MIP image that combines the first time phase and the third time phase, or may generate a combined MIP image that combines the second time phase and the third time phase. The generation function 143 may generate a blood vessel image based on the combined MIP image, and the display control function 146 may display the generated blood vessel image on the display 130.

[0060] The generation function 143 may, for example, generate an MIP image by combining one time phase and multiple time phases (for example, two time phases). Fig. 8 is a diagram showing an example of an image of a procedure for combining images for one time phase and two time phases. The generation function 143 may, for example, generate a combined MIP image TimeMIP(t1, (t2, t3)) by combining an MIP image for the first time phase (= t1) with two time phase images t1 and t2 for the second time phase (= t2) and third time phase (= t3).

[0061] Similarly, the generation function 143 may generate a combined MIP image by combining the second time phase with two-phase images of the first and third time phases, or may generate a combined MIP image by combining the third time phase with two-phase images of the first and third time phases. The generation function 143 may further generate a blood vessel image based on the combined MIP image, and the display control function 146 may display the generated blood vessel image on the display 130. In this way, the medical image processing apparatus 100 ends the processing shown in FIG. 3.

[0062] In the first embodiment, the medical image processing device 100 analyzes the delay of the affected side relative to the unaffected side by comparing the feature values of the affected and unaffected sides derived for each of multiple time phases based on 4D CT images captured by the modality 30 with a threshold. This allows the user to accurately diagnose the condition of collateral circulation. Because collateral circulation is a factor that affects the patient's prognosis, feature values such as the left-right ratio can be used as indicators for determining treatment.

[0063] (Second embodiment) Next, a second embodiment will be described. Fig. 9 is a block diagram showing an example of the configuration of a medical image processing apparatus 200 of the second embodiment. The medical image processing apparatus 200 of the second embodiment differs from the medical image processing apparatus 100 of the first embodiment mainly in the configuration of the processing circuitry 140. The second embodiment will be described below, focusing on the differences from the first embodiment. In the following description, common elements will be assigned the same reference numerals and their description may be omitted.

[0064] The processing circuitry 140 in the medical image processing apparatus 200 of the second embodiment includes an acquisition function 141, a specification function 142, a generation function 143, a derivation function 144, an analysis function 145, a display control function 146, and a reception function 147. The other functions are common to the medical image processing apparatus 100 of the first embodiment.

[0065] The reception function 147 receives a user's specification of an MIP range. For example, the reception function 147 receives specification information transmitted by the input interface 120 when the user operates the input interface 120. The specification information is information that specifies an MIP range in a four-dimensional CT image. The reception function 147 is an example of a reception unit.

[0066] The identification function 142 identifies an MIP range in the 4D CT image based on the designation information received by the reception function 147. When identifying the MIP range, the identification function 142 divides the 4D CT image acquired by the acquisition function 141 into an affected side and a healthy side. The identification function 142 identifies the MIP range on each of the affected side and the healthy side. The identification function 142 may identify the MIP range based on information other than that received when designation information is received, for example, information on the location where an infarction is assumed to have occurred. The identification function 142 is an example of an identification unit.

[0067] The medical image processing device 200 of the second embodiment has the same effects as the medical image processing device 100 of the first embodiment. Furthermore, in the medical image processing device 200 of the second embodiment, the reception function 147 receives the user's specification of the MIP range. This allows the state of cerebral infarction in the MIP range requested by the user to be diagnosed with high accuracy. For example, the user can specify the range of only the MCA region where collateral circulation is particularly well developed.

[0068] In each of the above embodiments, the derivation function 144 derived the left-right inflow ratio, the left-right presence ratio, and the left-right outflow ratio as feature quantities for the affected side and the healthy side. Alternatively, the derivation function 144 may generate a side-specific collateral circulation time ratio by comparing the presence ratio of blood vessels between different time phases on the affected side and the healthy side. Furthermore, the analysis function 145 may determine a time phase delay based on the derived side-specific collateral circulation time ratios on the affected side and the healthy side.

[0069] The derivation function 144 calculates the affected-side collateral circulation time ratio Output(4), which is the affected-side collateral circulation time, by substituting the affected-side vascular pixel counts in multiple time phases into the following equation (5). The time change in the integrated value of the vascular pixel counts on the affected and healthy sides at this time is shown in a graph in Figure 10. Figure 10 is a diagram showing an example of the time change in the integrated value of the vascular pixel counts on the affected and healthy sides.

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[0070] The analysis function 145 analyzes the time phase delay of the affected side relative to the healthy side based on the affected-side collateral circulation time ratio Output(4) derived by the derivation function 144. For example, the analysis function 145 can calculate the amount of change in blood per unit time when processing the affected-side collateral circulation time ratio Output(4), which is the ratio of the number of blood vessel pixels in the first time phase to the integrated value of the number of blood vessel pixels in the first and third time phases, with a certain threshold. It may be determined that there is a time phase delay when the amount of change in blood is, for example, equal to or less than a predetermined threshold.

[0071] In each of the above embodiments, the analysis function 145 may analyze the delay in time phase based on the amount of change over time in the total filling volume on the affected side. The analysis function 145 may calculate the amount of change in volume of the fluid (contrast medium or blood) in the brain, Output(5), using the following equation (6), as the amount of change over time in the total filling volume on the affected side, and determine the delay in time phase based on the amount of change in volume of the fluid, Output(5). In this case, for example, a threshold value, for example 25 mm 3and it may be determined that there is a time phase delay when the amount of change Output(5) is equal to or less than the threshold value.

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[0072] According to at least one of the embodiments described above, the medical image processing apparatus includes an acquisition unit that acquires medical original images of a subject's brain at multiple time phases, with one of the left and right sides of the brain designated as the affected side and the other as the healthy side; a derivation unit that derives feature amounts related to collateral blood circulation in the subject's brain based on the acquired medical original images; and an analysis unit that analyzes the delay in time phase of the affected side relative to the healthy side based on a result of comparing the feature amounts of the affected side and the healthy side for each of the multiple time phases, thereby enabling accurate evaluation of the condition of a disease.

[0073] 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, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0074] 1. In-hospital system 10 Hospital Information System (HIS) 20 Radiology Information System (RIS) 30 Medical imaging diagnostic equipment (modality) 40 Picture Archiving and Communication System (PACS) 100 Medical image processing device 110 Communication Interface 120 input interface 130 Display 140 Processing Circuit 141 Acquisition Function 142 Specific Functions 143 Generation function 144 Derived Functions 145 Analysis Function 146 Display Control Function 147 Reception Function 150 memory 200 Medical image processing device NW Network

Claims

1. an acquisition unit that acquires medical original images of the brain at multiple time phases, with one of the left and right sides of the brain of the subject designated as an affected side and the other as a healthy side; a derivation unit that derives a feature amount related to collateral circulation in the brain of the subject based on the acquired original medical image; and an analysis unit that analyzes a delay in the time phase of the affected side relative to the healthy side based on a result of comparing the feature amounts of the affected side and the healthy side for each of the plurality of time phases. Medical imaging equipment.

2. a display control unit that displays delay information regarding the determined delay in the time phase on a display unit; The medical image processing device according to claim 1 .

3. the deriving unit derives a ratio of an amount of fluid flowing into a blood vessel on the affected side and an amount of fluid flowing into a blood vessel on the healthy side for each of the plurality of time phases; the analysis unit analyzes the time phase delay based on the ratio of the inflow amounts. The medical image processing device according to claim 1 .

4. the deriving unit derives an abundance ratio of blood vessels on the affected side and the healthy side for each of the plurality of time phases; the analysis unit analyzes the delay in the time phase based on the abundance ratio. The medical image processing device according to claim 1 .

5. the deriving unit derives a ratio of an outflow amount of fluid flowing out of a blood vessel on the affected side to an outflow amount of fluid flowing out of a blood vessel on the healthy side for each of the plurality of time phases; the analysis unit analyzes the phase delay based on the ratio of the outflow amounts. The medical image processing device according to claim 1 .

6. The analysis unit determines that there is a time phase delay when the ratio of the inflow amounts is less than a first threshold value. The medical image processing device according to claim 3 .

7. The analysis unit determines that there is a delay in the time phase when the abundance ratio is less than a second threshold value. The medical image processing device according to claim 4 .

8. The analysis unit determines that there is a time phase delay when the ratio of the outflow amounts is equal to or greater than a third threshold value. The medical image processing device according to claim 5 .

9. the deriving unit derives an affected-side collateral circulation time ratio by comparing the presence ratio of blood vessels between different time phases on the affected side; the analysis unit determines the delay in the time phase based on the affected-side collateral circulation time ratio. The medical image processing device according to claim 1 .

10. a generating unit that performs maximum intensity projection processing on the original medical image to generate a maximum intensity projection image, the derivation unit derives the feature amount based on the maximum intensity projection image. The medical image processing device according to claim 1 .

11. a specifying unit for specifying a projection processing range to be subjected to the maximum intensity projection processing; The medical image processing device according to claim 10.

12. further comprising a reception unit that receives designation of the projection processing range by a user; The medical image processing device according to claim 11 .

13. The analysis unit analyzes the delay in the time phase based on a time change in the total filling volume of the blood vessel on the affected side. The medical image processing device according to claim 1 .

14. the generating unit generates a blood vessel image based on the maximum intensity projection image; The blood vessel images at different time phases are displayed on a display unit in an overlapping manner. The medical image processing device according to claim 10.

15. The maximum intensity projection image is an image including at least one of an entire region of the brain, an anterior cerebral artery region, a middle cerebral artery region, and a posterior cerebral artery region. The medical image processing device according to claim 10.

16. The computer one of the left and right sides of the brain of the subject is designated as the affected side and the other is designated as the healthy side, and original medical images of the brain at multiple time phases are acquired; deriving a feature amount related to collateral blood circulation in the brain of the subject based on the acquired original medical image; analyzing a delay in the time phase of the affected side relative to the healthy side based on a result of comparing the feature amounts of the affected side and the healthy side for each of the plurality of time phases; Medical image processing methods.

17. On the computer, one of the left and right sides of the brain of the subject is designated as the affected side and the other is designated as the healthy side, and original medical images of the brain at multiple time phases are acquired; deriving a feature amount related to collateral blood circulation in the brain of the subject based on the acquired original medical image; analyzing a delay in the time phase of the affected side relative to the healthy side based on a result of comparing the feature amounts of the affected side and the healthy side for each of the plurality of time phases; program.

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