JP5053606B2 - Medical image diagnostic apparatus and medical image processing apparatus - Google Patents

Description

  The present invention relates to a medical image diagnostic apparatus and a medical image processing apparatus such as an X-ray CT apparatus, an MRI apparatus, an ultrasonic diagnostic apparatus, or an X-ray diagnostic apparatus, and in particular, from an acquired medical image, an organ such as a liver and pancreas, The present invention relates to a medical image diagnostic apparatus and a medical image processing apparatus that extract a region such as a blood vessel.

  Medical image diagnosis apparatuses such as an X-ray CT apparatus and an MRI apparatus can acquire a three-dimensional image. Regions of interest such as organs, blood vessels, and tumors are extracted from such 3D images and used for diagnosis, surgical planning, intraoperative navigation, and the like.

  However, it is not easy to extract the region of interest from the three-dimensional image. Conventionally, an operator manually designates a region of a target region or cuts a part of a three-dimensional image so as not to display a part of the three-dimensional image. Needed to be extracted. As described above, since it is necessary for the operator to manually extract the region of interest, time and labor are consumed, and the region of interest cannot be easily extracted and observed.

  On the other hand, a technique for extracting a region of interest from a three-dimensional image by using a template prepared for each organ has been proposed. However, since the position and shape of the organ differ depending on the patient, it is difficult to appropriately extract the region of the target region from the three-dimensional image by absorbing individual differences among the patients by this method.

  Further, by using the three-dimensional image data obtained by injecting the contrast medium into the subject and acquired at different time phases, the position of the liver region is estimated, and the liver region is A method of automatically extracting has been proposed (for example, Patent Document 1). However, the organs that can be extracted by applying this method are limited, and cannot be applied to various sites of interest.

  Conventionally, there has been a demand for a method that can easily extract a plurality of regions of interest, but as described above, it is difficult to extract a plurality of regions of interest using the conventional technique.

  In addition, there are many soft tissues such as organs in the abdomen, and the shape of the site of interest may change depending on the progress of the disease state. Therefore, there is a demand for a technique that can easily extract an organ region particularly in the abdomen.

JP 2002-345807 A

  The present invention solves the above-described problems, and an object thereof is to provide a medical image diagnostic apparatus and a medical image processing apparatus that can easily extract a region of a region of interest.

The invention according to claim 1, after the contrast agent is injected into the subject, by taking a predetermined imaging area of the subject at multiple time points a predetermined time has elapsed, to obtain a plurality of volume data Medical image acquisition means and subtraction means for generating first subtraction volume data by subtracting initial volume data from each of the volume data acquired at a plurality of time points after the contrast agent is injected into the subject. A region extracting means for extracting data of a region into which the contrast agent specified by the first subtracted volume data flows from the volume data acquired by the medical image acquiring means, and the plurality of extracted data A medical image diagnostic apparatus comprising: a combining unit that combines and generates combined data.

According to a second aspect of the present invention, the initial volume data is acquired by imaging a predetermined imaging region of the subject before the contrast agent is injected into the subject, and the contrast agent further includes the subject. after being injected into, by photographing a predetermined photographing area of the subject at multiple time points the elapse of a preset predetermined time, the medical image acquisition means for acquiring a plurality of volume data, wherein the contrast agent Subtracting means for generating first subtracted volume data at each time point by subtracting the initial volume data from each of the volume data acquired at a plurality of time points after being injected into the subject, and the medical image from the volume data acquired at any time by the acquiring means, the contrast agent identified by the first subtraction volume data in said each time point has flowed A region extracting means for extracting a position of the data, and characterized in that it comprises synthesizing means for generating a combined data by combining a plurality of data the extracted, display means for displaying the medical image based on the synthesized data, the This is a medical image diagnostic apparatus.

According to an eighth aspect of the present invention, volume data acquired by imaging a predetermined region of the subject at a plurality of time points after a predetermined time has elapsed after the contrast medium is injected into the subject. A subtraction that generates first subtracted volume data at each time point by subtracting initial volume data acquired by imaging the predetermined imaging area before the contrast agent is injected into the subject from each Means, and region extracting means for extracting, from volume data acquired by imaging a predetermined region of the subject, data of a site into which the contrast medium specified by the first subtraction volume data at each time point flows. a synthesizing means for synthesizing the plurality of data the extracted to generate combined data, and display means for displaying the medical image based on the synthesized data, A medical image processing apparatus characterized by having.

  According to the present invention, it is possible to generate and display a medical image representing a plurality of parts by extracting data representing the part into which the contrast agent has flowed and combining the plurality of extracted data. In addition, by subtracting the initial volume data from the volume data acquired when a predetermined time has elapsed, it is possible to generate first subtracted volume data that identifies the region into which the contrast agent has flowed. Then, by extracting the data of the part specified by the first subtraction volume data from the volume data acquired at an arbitrary time, it becomes possible to easily extract the data of the desired part.

  The configuration of the medical image diagnostic apparatus and medical image processing apparatus according to the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing a schematic configuration of a medical image diagnostic apparatus according to an embodiment of the present invention.

  The medical image diagnostic apparatus 1 includes a medical image acquisition unit 2, a medical image processing unit 3, a control unit 6, an imaging protocol storage unit 7, and a user interface (UI) 8. The medical image diagnostic apparatus 1 corresponds to, for example, an X-ray CT apparatus, an MRI apparatus, an ultrasonic diagnostic apparatus, or an X-ray diagnostic apparatus. Here, as an example, a case where the medical image diagnostic apparatus 1 is an X-ray CT apparatus will be described.

  The medical image acquisition unit 2 acquires medical image data such as two-dimensional tomographic image data and three-dimensional image data of a subject. The medical image processing unit 3 extracts image data representing the region of interest from the medical image data acquired by the medical image acquisition unit 2. The control unit 6 controls the overall operation of the medical image diagnostic apparatus 1. The user interface 8 displays a medical image acquired by the medical image acquisition unit 2 and an image of a region of interest extracted by the medical image processing unit 3, and includes an imaging protocol including imaging conditions for acquiring a medical image. Is used to input. Hereinafter, the configuration and operation of each unit of the medical image diagnostic apparatus 1 will be described.

(Medical image acquisition unit 2)
First, the configuration and operation of the medical image acquisition unit 2 will be described. The medical image acquisition unit 2 includes a scan control unit 21, an imaging unit 22, an image reconstruction unit 23, and an image storage unit 24. The medical image acquisition unit 2 irradiates the subject with an X-ray beam, detects the X-ray beam transmitted through the subject, and generates image data based on the detected X-ray projection data.

  The imaging protocol storage unit 7 stores an imaging protocol including preset imaging conditions. The imaging conditions include, for example, conditions such as the voltage value / current value of the X-ray source and the range of the imaging region. The scan control unit 21 controls photographing by the photographing unit 22 and image reconstruction by the image reconstruction unit 23 according to the photographing protocol stored in the photographing protocol storage unit 7.

  The imaging unit 22 includes a bed on which a subject is placed, an X-ray source, a high voltage generator, an X-ray detector, a data collection unit (DAS), a gantry (gantry) for storing them, and the like. X-ray projection data is acquired by irradiating the subject with an X-ray beam and detecting the X-ray beam transmitted through the subject. The X-ray source irradiates the subject with an X-ray beam. The X-ray detector detects an X-ray beam irradiated from the X-ray source and transmitted through the subject. For example, the X-ray detector has a plurality of X-ray detection elements arranged in an array in two directions orthogonal to each other, thereby forming a two-dimensional X-ray detector. The data acquisition unit (DAS) has data acquisition elements arranged in an array like the X-ray detection elements of the X-ray detector, and scans the X-ray beam detected by the X-ray detector. 21 is collected in correspondence with the data collection control signal output by 21. This collected data becomes X-ray projection data.

  The imaging unit 22 rotates the X-ray source around the subject while moving the bed on which the subject is placed in the body axis direction of the subject under the control of the scan control unit 21. The so-called helical scan is performed so that the relative trajectory of the subject is spiral.

  The image reconstruction unit 23 reconstructs image data by performing a back projection process on the X-ray projection data output from the imaging unit 22. This back projection method is the same as a known method. For example, reconstruction by a three-dimensional image reconstruction algorithm typified by a method called the Feldkamp method is performed, and X in a wide target region (volume) in the slice direction is performed. Three-dimensional distribution data (hereinafter referred to as “volume data”) of the linear absorption coefficient is generated. The volume data generated by the reconstruction process is stored in the image storage unit 24. This volume data is subjected to image processing such as volume rendering processing and MPR processing by a data processing device (not shown), thereby obtaining medical images such as three-dimensional image data and tomographic image data (MPR image data) of an arbitrary cross section. Converted to data. The converted medical image data is output to the display unit 81, and a medical image (such as a three-dimensional image or an MPR image) based on the medical image data is displayed on the display unit 81.

  Here, the imaging operation by the medical image acquisition unit 2 will be described with reference to FIGS. FIG. 2 is a diagram illustrating a three-dimensional space for explaining a three-dimensional imaging region. FIG. 3 is a diagram illustrating imaging timing and contrast medium concentration (luminance value). In this embodiment, the medical image acquisition unit 2 captures and acquires image data while a contrast medium is injected into the subject.

  In so-called contrast examinations, a contrast agent injected into a blood vessel of a subject by drip or blood vessel injection travels in the bloodstream and reaches the target organ. A lesion or an abnormality of an organ can be found by observing the presence or absence of the contrast effect when the contrast agent permeates or the difference in the degree, or observing the shape of the contrast portion.

  In contrast medium imaging with an X-ray CT apparatus, after a contrast medium is injected into a subject, a scan (hereinafter sometimes referred to as “main scan”) is started at the timing when the contrast medium flows into the target organ. To capture the image data.

  In order to measure the timing, a scan for observing a change in contrast agent concentration in the region of interest of the subject into which the contrast agent has been injected (hereinafter sometimes referred to as a “prep scan”) is performed before the main scan. Execute. This prep scan is a scanning method in which X-ray projection data of an object is collected and image reconstruction is performed at the same time, and an image is displayed while scanning. Then, based on the image obtained by this prep scan, the contrast agent concentration (CT value) in the region of interest is automatically judged, and when the contrast agent concentration becomes high to some extent, the prep scan is stopped. The main scan (for example, helical scan) is started. For example, when the concentration of the contrast agent (CT value) is equal to or higher than a threshold value, the main scan is automatically started.

  Further, immediately after the contrast agent is injected into the subject, the contrast agent does not flow into the region of interest, so the concentration (CT value) of the contrast agent in the region of interest is low. As time further elapses, the contrast agent flows into the region of interest and the CT value increases. When the CT value of this region of interest exceeds a predetermined threshold, it is considered that the contrast medium has also flowed into the target organ, and a timing signal for starting the main scan (helical scan) is generated at this point. . Thus, the main scan is automatically started, and imaging can be started when the contrast agent flows into the target organ.

  Prior to the prep scan, imaging slice positioning, prep scan conditions (tube voltage, tube current, scan time, helical pitch, etc.), main scan conditions (helical scan conditions), and CT value thresholds are set. These conditions are stored in the imaging protocol storage unit 7 as imaging conditions. These conditions are input by the operator using the user interface 8. The main scan condition (helical scan condition) includes tube voltage, tube current, scan time, helical pitch, information indicating the range of the imaging region, and the like.

  For example, as shown in FIG. 2, a three-dimensional imaging region 100 in the subject is set as a region to be imaged by the main scan (helical scan), and the prep scan imaging position 101 is subjected to the prep scan to obtain the contrast agent concentration. The position to observe the change of. In the example illustrated in FIG. 2, the prep scan shooting position 101 is set at a position away from the shooting area 100, but may be set within the shooting area 100. Information (position information) indicating the position of the imaging region 100 and information (position information) indicating the prep scan imaging position 101 are included in the imaging conditions and stored in the imaging protocol storage unit 7 in advance.

(Prep scan)
When performing the prep scan, the prep scan is performed under the control of the scan control unit 21 according to the prep scan condition. In other words, the imaging unit 22 generates an X-ray beam from the X-ray source according to the prep scan condition while continuously rotating the X-ray source and the X-ray detector around the subject, and performs prep scan imaging of the subject. The position 101 is irradiated with an X-ray beam. Then, the X-ray beam transmitted through the subject is detected by the X-ray detector.

  Then, a contrast agent is injected into the subject, and the imaging unit 22 performs a prep scan, whereby X-ray projection data at the prep scan imaging position 101 is acquired, and the image reconstruction unit 23 performs a reconstruction process. Tomographic image data (monitoring image data) is generated. Then, the scan control unit 21 monitors the change in the contrast agent concentration (CT value) in the monitoring ROI 102 set in the monitoring image.

  The monitoring ROI 102 can be set at an arbitrary position by an operator, but is preferably set at a place where a change in the concentration of the contrast agent is easily detected. For example, as shown in FIG. 2, by setting so as to include a blood vessel 103 into which a contrast medium flows, it becomes easy to detect a concentration change of the contrast medium. When the CT value in the monitoring ROI 102 becomes equal to or greater than the threshold value, a timing signal indicating the start of the main scan (helical scan) is generated.

  The scan control unit 21 extracts CT values of a plurality of pixels in the monitoring ROI 102 set in advance from the monitoring image data obtained by executing the prep scan. For example, the scan control unit 21 calculates the sum of CT values of a plurality of pixels in the monitoring ROI 102 or calculates an average value thereof. The scan control unit 21 obtains the timing for starting the main scan (helical scan) based on the change in the CT value in the monitoring ROI 102.

  Then, the scan control unit 21 compares the CT value threshold set prior to the prep scan with the CT value in the monitoring ROI 102 and determines whether or not the CT value in the monitoring ROI 102 is equal to or greater than the threshold. To do.

  When the CT value in the monitoring ROI 102 is equal to or greater than the threshold value, it is considered that the contrast agent has flowed into the target organ. Therefore, the scan control unit 21 causes the imaging unit 22 to stop the prep scan and perform the main scan according to the main scan condition. To start.

  On the other hand, when the CT value in the monitoring ROI 102 is less than the threshold value, the scan control unit 21 causes the imaging unit 22 to continuously execute the prep scan. Then, until it is determined that the CT value in the monitoring ROI 102 is equal to or greater than the threshold value, the scan control unit 21 causes the imaging unit 22 to continuously perform the prep scan.

  When performing the main scan, under the control of the scan control unit 21, the imaging unit 22 irradiates the X-ray beam from the X-ray source and moves the bed to perform imaging by executing a helical scan.

  In this scan, a helical scan is executed according to the imaging protocol. For example, the imaging unit 22 images the same imaging region 100 shown in FIG. 2 a plurality of times, and performs imaging at a timing when different parts are contrasted.

  Since the contrast agent has fluidity, it moves and diffuses rapidly on the bloodstream, and thus flows away from the target organ with the passage of time. Moreover, the timing at which the contrast agent flows in varies depending on the site. If the contrast medium flows away, the concentration of the contrast medium decreases and the contrast effect decreases. For example, the contrast medium flows into the artery, and then the contrast medium flows out of the artery, the contrast medium flows into the pancreatic parenchyma, and then the contrast medium flows out of the pancreatic parenchyma, and the contrast medium flows into the liver parenchyma. To do. Thus, the timing at which the contrast agent flows in varies depending on the site.

  Here, the timing of imaging by the imaging unit 22 will be described with reference to FIG. First, before injecting the contrast agent into the subject, the imaging unit 22 performs a helical scan on the imaging region 100 to obtain X-ray projection data of the imaging region 100 in a state where no contrast agent is injected. get. Then, the image reconstruction unit 23 generates volume data 300 based on the X-ray projection data and stores it in the image storage unit 24. The volume data 300 acquired before the contrast agent is injected into the subject is hereinafter referred to as “initial volume data”.

Then, a contrast medium is injected into the subject, and the imaging unit 22 executes a prep scan under the control of the scan control unit 21. When the CT value of the monitoring ROI 102 set on the monitoring image acquired by the prep scan becomes equal to or greater than the threshold value, the scan control unit 21 causes the imaging unit 22 to start a main scan (helical scan). As shown in FIG. 3, a time phase t ₀ the time of this main scan start.

  Then, the imaging unit 22 acquires the X-ray projection data of the imaging region 100 by executing a helical scan according to the imaging protocol stored in the imaging protocol storage unit 7. At this time, the imaging unit 22 performs helical scanning for the same imaging region 100 a plurality of times.

  The image reconstruction unit 23 generates volume data of the imaging region 100 in each time phase based on the X-ray projection data acquired by the imaging unit 22. The volume data in each time phase is stored in the image storage unit 24.

  As described above, while the imaging unit 22 is executing the helical scan, the contrast medium flows into the artery, the contrast medium flows out from the artery, flows into the pancreatic parenchyma, and then flows from the pancreatic parenchyma. Flows away and flows into the liver parenchyma. Meanwhile, since the imaging unit 22 performs a helical scan, it is possible to obtain volume data showing how the contrast agent flows into each part.

(Medical image processing unit 3)
Next, the configuration and operation of the medical image processing unit 3 will be described. The medical image processing unit 3 includes an extraction area determination unit 4 and an image generation unit 5. The extraction region determination unit 4 obtains the shape and position of the site of interest from the volume data acquired by the medical image acquisition unit 2. Based on the volume data acquired at an arbitrary time phase based on the volume data acquired at an arbitrary time phase and the shape and position of the region of interest obtained by the extraction region determination unit 4, Data of the attention site is extracted, and image data for display is generated.

  First, the extraction region determination unit 4 will be described with reference to FIGS. 2 to 4, and then the image generation unit 5 will be described with reference to FIGS. 2 to 6. FIG. 4 is a schematic diagram for explaining a subtraction process for volume data. FIG. 5 and FIG. 6 are schematic diagrams for explaining extraction processing of data of a target region.

  The extraction region determination unit 4 includes a reference image acquisition unit 41, a subtraction unit 42, and a type data generation unit 43.

The reference image acquisition unit 41 acquires, from the image storage unit 24, volume data acquired after a preset time has elapsed since the start of the main scan (time phase t ₀ ). This preset time is a time set assuming that the contrast agent flows into the region of interest, and is included in the imaging protocol and stored in the imaging protocol storage unit 7 in advance.

  Here, the timing at which the contrast agent flows into the site of interest will be described with reference to the graph of FIG. In the graph shown in FIG. 3, the horizontal axis indicates time, and the vertical axis indicates the concentration (luminance value) of the contrast agent. The luminance curve 201 is a curve representing a temporal change in the luminance value (contrast medium concentration) in the artery, and the luminance curve 202 is a curve representing the temporal change in the luminance value (contrast medium concentration) in the pancreatic parenchyma. A curve 203 is a curve representing a temporal change in the luminance value (contrast medium concentration) in the liver parenchyma.

Luminance curves 201 to 203 estimate temporal changes in luminance values (contrast medium concentration) at each site with reference to the time when the contrast medium is injected into the subject or the time when the main scan starts (time phase t ₀ ). It is a curved line. The time required for the contrast medium to flow into each site after the contrast medium is injected into the subject can be statistically estimated, and a luminance curve is created in advance based on the estimation. Further, since there is a difference in the time during which the contrast medium flows in depending on the part, there is a difference in the time phase at which the luminance value (contrast medium concentration) becomes maximum between the luminance curves 201 to 203. Therefore, it is possible to estimate a region where the concentration (brightness value) of the contrast agent has flowed and the concentration (luminance value) is high on the basis of the time when the contrast agent is injected or the time phase t ₀ as a reference. it can. For the luminance curves 201 to 203, for example, a statistically obtained luminance curve of each part can be used, or an average of the luminance curves of each part acquired in the past can be used.

For example, as in a luminance curve 201 shown in FIG. 3, after the contrast agent is injected into the subject, the contrast agent gradually flows into the artery, so that the concentration of the contrast agent in the artery gradually increases (gradually increases in luminance). It is assumed that the concentration of the contrast medium in the artery reaches the maximum value (the luminance value is maximum) at the time phase t ₁ when the time Δt ₁ has elapsed from the time of starting the main scan (time phase t ₀ ). . Thereafter, the contrast medium gradually flows away from the artery, and the concentration of the contrast medium in the artery gradually decreases (the luminance value gradually decreases). Accordingly, the reference image acquisition unit 41 uses the time point t ₁ when the time Δt ₁ has elapsed from the time phase t ₀ as a reference, and the image storage unit stores the volume data 301 acquired at the time Δt ₁ from the time point when the main scan starts (time phase t ₀ ). 24. Thereby, volume data in which the luminance value (CT value) of the artery is higher than the luminance value of the surrounding area can be acquired. In the volume data 301 shown in FIG. 3, the part 301 </ b> A is a part where the contrast agent flows and the concentration of the contrast agent is high. That is, since the luminance value (CT value) of the part 301A is higher than the luminance value in the surrounding area, this part 301A is assumed to represent an artery.

Further, as shown by the luminance curve 202, after the contrast agent flows into the artery, the contrast agent gradually flows into the pancreatic parenchyma, so that the concentration of the contrast agent in the pancreatic parenchyma gradually increases (the luminance value gradually increases). It is assumed that the concentration of the contrast medium in the pancreatic parenchyma reaches the maximum value (the luminance value is maximum) at time phase t ₂ when time Δt ₂ has elapsed from the time when the main scan starts (time phase t ₀ ). Thereafter, the contrast medium gradually flows away from the pancreatic parenchyma, and the concentration of the contrast medium in the pancreatic parenchyma gradually decreases (the luminance value gradually decreases). Therefore, the reference image acquisition unit 41, based on the time point of the scan start (time phase t _0), the time phase t ₀ is obtained in the phase t ₂ when Delta] t ₂ has elapsed since the volume data 302 to the image storage unit 24. Thereby, volume data in which the luminance value (CT value) of the pancreatic parenchyma is higher than the luminance value (CT value) in the surrounding region can be acquired. In the volume data 302 shown in FIG. 3, the portion 302A is a portion where the contrast agent flows in and the concentration of the contrast agent is high. That is, since the luminance value (CT value) of the part 302A is higher than the luminance value in the surrounding area, this part 302A is assumed to represent the pancreatic parenchyma.

Further, as shown by the luminance curve 203, after the contrast medium flows into the pancreatic parenchyma, the contrast medium gradually flows into the liver parenchyma, so that the concentration of the contrast medium in the liver parenchyma gradually increases (gradually the luminance value). It is assumed that the concentration of the contrast medium in the liver parenchyma reaches the maximum value (the luminance value is maximum) at the time phase t ₃ when the time Δt ₃ has elapsed from the start of the main scan (time phase t ₀ ). . Thereafter, the contrast medium gradually flows out of the liver parenchyma, and the concentration of the contrast medium in the liver parenchyma gradually decreases (the luminance value gradually decreases). Therefore, the reference image acquisition unit 41 uses the time point when the main scan starts (time phase t ₀ ) as a reference, and the volume data 303 acquired at time phase t ₃ when the time Δt ₃ has elapsed from the time phase t ₀ as an image storage unit. 24. Thereby, it is possible to acquire volume data in which the luminance value (CT value) of the liver parenchyma is higher than the luminance value (CT value) in the surrounding area. In the volume data 303 shown in FIG. 3, the region 303 </ b> A is a region where the contrast agent flows in and the concentration of the contrast agent is high. That is, since the luminance value (CT value) of the part 303A is higher than the luminance value in the surrounding area, it is assumed that the part 303A represents the liver parenchyma.

That is, the reference image acquisition unit 41 acquires the volume data 301 acquired after the time Δt ₁ from the time point of starting the main scan (time phase t ₀ ) from the image storage unit 24 and acquires the time data t ₂ after the time phase t _0. is the volume data 302 acquired from the image storage unit 24, it acquires the volume data 303 acquired from the time phase t ₀ after a time Delta] t ₃ from the image storage unit 24. Since these volume data are data in which the contrast medium flows into different parts and the luminance values (CT values) of the different parts are high, these are representative volume data (reference volume) of each part. Data). Hereinafter, the volume data acquired by the reference image acquisition unit 41 will be referred to as “reference volume data”.

Note that the time Δt ₁ (time phase t ₁ ), the time Δt ₂ (time phase t ₂ ), and the time Δt ₃ (time phase t ₃ ) are preset times and are included in the imaging protocol in advance. Stored in the imaging protocol storage unit 7. The reference image acquisition unit 41 acquires volume data acquired at the time phase t ₁ , the time phase t _2, and the time phase t ₃ from the image storage unit 24 in accordance with the imaging protocol stored in the imaging protocol storage unit 7. .

  The subtraction unit 42 acquires volume data (initial volume data) acquired before injecting the contrast medium into the subject from the image storage unit 24, and uses the reference volume data of each part acquired by the reference image acquisition unit 41. Subtract that initial volume data. That is, the subtracting unit 42 subtracts the voxel value of the initial volume data from the voxel value of the reference volume data of each part. The reference volume data of each part is data in which the contrast medium flows into a specific part and the luminance value of the part is high, and the initial volume data is obtained before the contrast medium is injected into the subject. It is data. Therefore, by subtracting the initial volume data from the reference volume data of each part, the subtracted volume data represents a part into which the contrast agent is flowing (hereinafter sometimes referred to as “target part”). Data will be left behind. The process of subtracting the initial volume data from the reference volume data is referred to as “first subtraction process” for the sake of convenience, and the volume data generated by this subtraction process is referred to as “first subtraction volume data”. Thus, the site | part into which the contrast agent inflows can be pinpointed with 1st subtraction volume data.

  Since the reference volume data is assumed that the luminance value (CT value) of the region of interest is relatively higher than the surrounding region, before injecting the contrast agent into the subject from the reference volume data By subtracting the acquired initial volume data, a portion having a relatively high voxel value after the subtraction represents the region of interest.

For example, in the reference volume data 301 acquired at the time phase t _{1 in} which the contrast agent concentration (CT value) of the artery is assumed to be high, the luminance value (CT value) of the artery is relatively higher than the surrounding region. It is assumed that Therefore, as shown in FIG. 4, the subtraction unit 42 subtracts the initial volume data 300 from the reference volume data 301 to generate first subtracted volume data 310 after the subtraction. In the first subtraction volume data 310, a portion having a relatively high voxel value represents an artery. In the first subtraction volume data 310 shown in FIG. 4, the part 301A is a part where the contrast agent flows and the concentration of the contrast agent is high, and this part 301A represents an artery. As described above, the artery can be specified by the first subtraction volume data 310.

Further, the reference volume data 302 acquired at the time phase t _{2 in} which the concentration (CT value) of the contrast medium in the pancreatic parenchyma is assumed to be higher than that of the surrounding region. It is assumed that the price is high. Therefore, as shown in FIG. 4, the subtraction unit 42 subtracts the initial volume data 300 from the reference volume data 302 to generate first subtracted volume data 311 after the subtraction. In the first subtracted volume data 311, the portion having a relatively high voxel value represents the pancreatic parenchyma. In the first subtraction volume data 311 shown in FIG. 4, the region 302A is a region where the contrast agent flows and the concentration of the contrast agent is high, and this region 302A represents the pancreatic parenchyma. Thus, the pancreatic parenchyma can be specified by the first subtraction volume data 311.

In addition, the reference volume data 303 acquired at the time phase t _{3 in} which the concentration of the contrast medium in the liver parenchyma (CT value) is assumed to be high, the brightness value (CT value) of the liver parenchyma is relative to the surrounding region. It is assumed that the price is high. Therefore, the subtracting unit 42 generates the first subtracted volume data after subtraction by subtracting the initial volume data 300 from the reference volume data 303. In the first subtracted volume data, a portion having a relatively high voxel value represents liver parenchyma.

  The first subtraction volume data generated by the subtraction unit 42 is stored in the image storage unit 31 installed in the medical image processing unit 3.

  In addition, when a contrast agent flows into a certain part, the concentration of the contrast medium at that part becomes maximum at a certain time phase, and then the contrast medium flows away, so the concentration of the contrast medium at that part decreases, For some time, contrast agent remains at the site. For this reason, in the volume data acquired at a later time phase, the luminance value of the previously contrasted portion is a value corresponding to the contrast agent remaining in the region.

For example, as shown by the luminance curve 201 in FIG. 3, the luminance value (contrast agent concentration) becomes maximum at the time phase t ₁ , and then the contrast agent flows away from the artery. concentration) is reduced, but kept a certain value is the brightness value even in a time phase t ₂ and time phase t _3. This is also in the time phase t ₂ and time phase t _3, because the contrast agent remains in the artery. Further, as indicated by luminance curve 202, the luminance value in the time phase t ₂ (the concentration of the contrast medium) is maximized, then, since walks away contrast medium flows from pancreatic parenchymal, luminance value (the concentration of the contrast medium) is decreased, the luminance value even in a time phase t ₃ is kept a certain value. This is also in the time phase t _3, because the contrast medium remaining in the pancreatic parenchyma.

For example, in the time phase t ₂ , since the contrast medium remains in the region imaged before the time phase t ₂ , the contrast medium remains in the reference volume data 302 acquired in the time phase t _2. The luminance value of the existing part becomes high (the CT value becomes large). That is, in the time phase t _2, since the contrast agent into an artery is left, in the reference volume data 302 acquired in time phase t _2, the luminance value of a portion corresponding to the artery, the contrast agent remaining The value is in accordance. In the reference volume data 302 shown in FIG. 3, the portion 302A corresponding to the pancreatic parenchyma is a portion where the contrast agent flows in and the concentration of the contrast agent is high, but the contrast agent is present in the portion 302B corresponding to the artery. The luminance value (CT value) of the portion 302B remains and becomes a value corresponding to the remaining contrast agent. Thus, the reference volume data 302 acquired in a time phase t _2, the contrast agent to the site 302B, which is the contrast in time phase t ₂ previously will remain.

Therefore, from the reference volume data 302 acquired in a time phase t _2, the first subtraction volume data 311 obtained as a result of subtracting the initial volume data 300, the voxel value of a portion corresponding to the pancreatic parenchyma is relatively high In addition, the voxel value of the portion corresponding to the artery also becomes a value corresponding to the contrast agent remaining in the artery. Therefore, from the reference volume data 302 acquired in a time phase t _3, by simply subtracting the initial volume data 300 may not be able to extract only region of the pancreatic parenchyma, the first subtraction volume data 311, A region corresponding to an artery is also included. The first subtraction volume data 311 shown in FIG. 4 includes a portion 302A corresponding to the pancreatic parenchyma, but also includes a portion 302B corresponding to the artery. Thus, the first subtraction volume data 311 generated from the reference volume data 302 acquired in a time phase t ₂ is the contrast agent to the site 302B, which is the contrast in time phase t ₂ previously will remain.

Therefore, from the reference volume data 302 acquired in a time phase t _2, to remove the imaging portion in time phase t ₂ previously, subtraction unit 42, as shown in FIG. 4, the first subtraction volume data 311 The first subtraction volume data 310 is subtracted. That is, since the artery is first contrasted, the first subtraction volume data 310 includes only the artery region (part 301A). Then, the first subtraction volume data 310 representing the arterial area is subtracted from the first subtraction volume data 311 including the arterial area (part 302B) and the pancreatic parenchyma area (part 302A). Only the pancreatic parenchyma region (part 302A) is left in the volume data 320 generated as a result of the processing. This subtraction process for the second time is referred to as “second subtraction process” for the sake of convenience, and the volume data generated by this second subtraction process is referred to as “second subtraction volume data”. The second subtraction volume data is stored in the image storage unit 31 installed in the medical image processing unit 3. Thus, the pancreatic parenchyma can be specified by the second subtraction volume data 320.

In the time phase t _3, since the contrast agent to the site that is the contrast in time phase t ₃ earlier remaining, the reference volume data 303 acquired in a time phase t _3, the contrast medium remains The luminance value of the existing part becomes high (the CT value becomes large). That is, in the time phase t _3, since the contrast medium into an artery or pancreatic parenchyma is left, in the reference volume data 303 acquired in a time phase t _3, the luminance value of a portion corresponding to the arterial and pancreatic parenchyma is The value corresponds to the remaining contrast agent. In the reference volume data 303 shown in FIG. 3, the region 303A corresponding to the liver parenchyma is a region where the contrast agent has flowed in and the concentration of the contrast agent is high, but the region 303B corresponding to the artery or the pancreatic parenchyma The contrast agent remains in the portion 303C corresponding to the above, and the luminance values (CT values) of the portions 303B and 303C become values corresponding to the remaining contrast agent. Thus, the reference volume data 303 acquired in a time phase _{t 3,} time phase _{t 3} sites are contrast in previous 303B, the contrast medium 303C remained to.

Therefore, from the reference volume data 303 acquired in a time phase t _3, in the first subtraction volume data obtained as a result of subtracting the initial volume data 300, the voxel value of a portion corresponding to the hepatic parenchyma is relatively high In addition, the voxel values corresponding to the arteries and pancreatic parenchyma are values corresponding to the contrast agent remaining in the arteries and pancreatic parenchyma. Therefore, from the reference volume data 303 acquired in a time phase t _3, by simply subtracting the initial volume data 300 may not be able to extract only region of the hepatic parenchyma, the first subtraction volume data, arterial And an area corresponding to the liver parenchyma is also included.

Therefore, generated from the reference volume data 303 acquired in a time phase t _3, to remove the portion contrast to time phase t ₃ earlier, from the subtraction unit 42, the reference volume data 303 acquired in a time phase t ₃ from the first subtraction volume data, subtracting the first subtraction volume data generated from a temporal t ₃ volume data previously acquired. For example, the first subtraction volume data generated from the volume data 303 acquired in a time phase t _3, subtracting the first subtraction volume data 311. That is, the first subtraction volume data 311, because it contains the region of space and parenchyma of the artery, the first subtraction volume data generated from the reference volume data 303 acquired in a time phase t _3, arterial By subtracting the first subtraction volume data 311 in which the region of the pancreas and the region of the pancreatic parenchyma are subtracted, the second subtraction volume data generated as a result of the subtraction process includes only the liver parenchyma region (part 303A). Will be left behind. Thus, the liver parenchyma can be specified by the second subtraction volume data.

  As described above, in order to remove the portion imaged before the predetermined time phase from the volume data acquired at the predetermined time phase, the subtraction unit 42 obtains the reference volume data acquired at the predetermined time phase. By subtracting the first subtraction volume data generated from the volume data acquired before the predetermined time phase from the first subtraction volume data generated from the second subtraction volume data, the second subtraction volume data in the predetermined time phase is obtained. Generate. As a result, the second subtraction volume data in the predetermined time phase includes only the region of the region where the contrast agent concentration is relatively high in the predetermined time phase. Based on the volume data, it is possible to identify a region where the concentration of the contrast agent is high at the predetermined time phase.

  The type data generation unit 43 reads the volume data (first subtraction volume data or second subtraction volume data) generated as a result of the subtraction process by the subtraction unit 42 from the image storage unit 31, and stores the part data included in the volume data. Generate type data representing shape and position. For example, the first subtraction volume data 310 includes an arterial region, and the voxel value of the region is relatively higher than the surrounding region. For example, the type data generation unit 43 performs binarization processing to convert the value of the region where the voxel value is higher than the threshold value to “1”, and converts the values of the other regions to “0”. This threshold value is a value for distinguishing between the site where the contrast agent flows and the other site. By this binarization process, the value of the artery region is converted to “1”, and the value of the region other than the artery is converted to “0”. As a result, the type data represents the shape and position of the artery by the values “1” and “0”.

  Similarly, for the second subtraction volume data 320, the type data generation unit 43 performs binarization processing, converts the value of the region where the voxel value is higher than the threshold value to “1”, and values of the other regions Is converted to “0”. As a result, the value of the region of the pancreatic parenchyma is converted to “1”, and the value of the region other than the pancreatic parenchyma is converted to “0”. As a result, the type data represents the shape and position of the pancreatic parenchyma by the values “1” and “0”.

  Further, the type data generation unit 43 may perform a binarization process on the first subtraction volume data 311. Since the first subtracted volume data 311 includes not only the pancreatic parenchymal region but also the arterial region, the first subtracted volume data 311 is a type that represents the shape and position of the pancreatic parenchyma and artery by binarization processing. Data will be generated. In order to remove the arterial region from the mold data representing the shape and position of the pancreatic parenchyma and artery, the subtracting unit 42 represents the shape and position of the artery from the mold data representing the position and shape of the pancreatic parenchyma and artery. Subtract type data. As a result of this subtraction process, type data representing the position and shape of the pancreatic parenchyma is generated.

  As described above, the extraction area determination unit 4 generates type data representing the shape and position of each part. This type data is stored in the image storage unit 31 installed in the medical image processing unit 3. Since each part can be specified by this type data, it is used for processing for extracting data of a desired part from volume data acquired at an arbitrary time phase by the medical image acquisition unit 2.

  The subtracting unit 42 may delete unnecessary voxels by performing processing using a morphological filter. As a result, the region can be extracted with higher accuracy.

  Next, the image generation unit 5 will be described with reference to FIGS. The image generation unit 5 includes an area extraction unit 51, a synthesis unit 52, and an image processing unit 53.

  The region extraction unit 51 reads from the image storage unit 31 the type data specifying the part designated by the operator, and extracts the data of the part from the volume data acquired at the time phase designated by the operator. Since the type data represents the shape and position of the part, the region extracting unit 51 extracts the data of the part specified by the type data from the volume data.

  When the operator designates a part in advance before photographing, information indicating the part is included in the photographing protocol and stored in the photographing protocol storage unit 7. The area extraction unit 51 reads from the image storage unit 31 the type data specifying the part included in the imaging protocol, and extracts the data of the part from the volume data acquired at the time phase designated by the operator. In addition, when the operator designates a part using the user interface 8 after the start of imaging, the region extracting unit 51 reads type data for specifying the designated part from the image storage unit 31 and is designated by the operator. The data of the part is extracted from the volume data acquired at the time phase.

  FIG. 5 shows an example of region extraction. For example, when extracting liver parenchyma data from the volume data 410 acquired at an arbitrary time phase, the mold data 400 specifying the liver parenchyma generated by the mold data generator 43 is used. The type data 400 represents the shape and position of the liver parenchyma. The region extraction unit 51 extracts liver parenchyma data specified by the type data 400 from the volume data 410. The volume data 420 obtained by this extraction process represents liver parenchyma at an arbitrary time phase.

  In addition, when extracting the portal vein from the volume data 411 acquired at an arbitrary time phase, the type data 401 specifying the portal vein generated by the type data generating unit 43 is used. The type data 401 represents the shape and position of the portal vein. The area extraction unit 51 extracts the portal vein data specified by the type data 401 from the volume data 411. The volume data 421 obtained by this extraction process represents the portal vein at an arbitrary time phase.

  The synthesizer 52 synthesizes a plurality of volume data output from the area extractor 51 to generate synthesized data. At this time, the synthesizing unit 52 performs alignment by matching the coordinate systems of the plurality of volume data to generate synthesized data.

  For example, as shown in FIG. 5, the synthesized data 430 is generated by synthesizing the volume data 420 and the volume data 421 extracted by the region extracting unit 51. Since the volume data 420 represents the liver parenchyma and the volume data 421 represents the portal vein, the composite data 430 represents the liver parenchyma and the portal vein.

  The image processing unit 53 receives the synthesized data (volume data) output from the synthesizing unit 52 and observes the extracted region by applying a three-dimensional display method such as volume rendering or surface rendering to the synthesized data. 3D image data for the purpose and 3D image data representing the appearance are generated. Further, the image processing unit 53 may generate tomographic image data (MPR image data) in an arbitrary cross section by performing MPR processing on the combined data. Medical image data such as three-dimensional image data generated by the image processing unit 53 is output to the display unit 81, and an image based on the medical image data is displayed on the screen of the display unit 81.

  For example, the image processing unit 53 performs volume rendering on the combined data 430 generated by the combining unit 52, thereby generating three-dimensional image data representing the liver parenchyma and the portal vein. The three-dimensional image data is output to the display unit 81, and a three-dimensional image representing the liver parenchyma and portal vein is displayed on the screen of the display unit 81.

  In addition, the image processing unit 53 receives the volume data output from the region extraction unit 51, and performs image processing such as volume rendering and MPR processing on the volume data, thereby generating three-dimensional image data, MPR image data, and the like. May be generated.

  For example, the image processing unit 53 receives the volume data 420 and the volume data 421 extracted by the region extraction unit 51, and performs image processing such as volume rendering on the volume data 420 and medical data such as three-dimensional image data. Generate image data. By performing volume rendering on the volume data 420, liver three-dimensional image data is generated, and by performing volume rendering on the volume data 421, portal three-dimensional image data is generated.

  Alternatively, medical image data may be generated by performing image processing on the volume data by the image processing unit 53, and then a plurality of medical image data may be superimposed and displayed on the display unit 81. For example, the image processing unit 53 generates the three-dimensional image data based on the volume data 420 representing the liver parenchyma, and further generates the three-dimensional image data based on the volume data 421 representing the portal vein. You may display on the display part 81 in piles.

  As described above, by using the time for the contrast medium to flow into each part, type data representing the shape and position of each part is generated, and using the type data, the volume acquired at an arbitrary time phase Data of each part can be easily extracted from the data.

  In addition, by combining data of different parts, it is possible to generate and display medical image data such as three-dimensional image data representing a plurality of parts. Thereby, it becomes possible to grasp the positional relationship among a plurality of parts.

  In addition, the operator can automatically extract data corresponding to the part from the volume data only by designating the part desired to be observed, and generate medical image data of the part.

(Application example 1 of the image generation unit 5)
Here, the application example 1 of the process by the image generation part 5 is demonstrated with reference to FIG. By using a plurality of type data generated by the type data generation unit 43, data of a desired part is extracted from volume data acquired at an arbitrary time phase, and volume data including a plurality of regions is synthesized. be able to.

Here, based on the volume data acquired in the phase t ₂ when a time phase t _1, will be described for one example of generating medical image data of the hepatic parenchyma and portal vein.

First, a case where data of different parts acquired at the same time phase is synthesized will be described. For example, a case will be described in which medical image data is generated by combining liver parenchyma and portal vein data acquired at time phase t ₁ .

Before photographing, the part for extracting the time phase t ₁ (liver parenchyma and portal vein) is, if designated by the operator, the imaging protocol stored information indicating the extracted site that time phase t ₁ and is included in the imaging protocol Stored in the unit 7. The region extraction unit 51 acquires the volume data 412 acquired at the time phase t ₁ from the image storage unit 24 according to the information indicating the time phase and the part included in the imaging protocol, and further, type data for specifying the liver parenchyma 400 and type data 401 specifying the portal vein are acquired from the image storage unit 31. In addition, after the start of imaging, when the operator designates the time phase and the part by the user interface 8, the area extraction unit 51 obtains the volume data 412 obtained at the designated time phase from the image storage unit 24, Further, the mold data 400 and 401 for specifying the designated part are acquired from the image storage unit 31.

Then, the region extraction unit 51 extracts liver parenchyma data from the volume data 412 acquired at the time phase t ₁ by using the type data 400 that specifies the liver parenchyma. The volume data 422 obtained by this extraction process represents the liver parenchyma at the time phase t ₁ . Further, the region extracting unit 51 extracts portal vein data from the volume data 412 acquired at the time phase t ₁ by using the portal vein type data 401. The volume data 424 obtained by this extraction process represents the portal vein at the time phase t ₁ .

The combining unit 52 generates combined data by combining the volume data extracted by the region extracting unit 51. For example, the combining unit 52 includes a volume data 422 representing the hepatic parenchyma in time phase t _1, to synthesize the volume data 424 representing the portal at the same time phase t _1, the liver parenchyma in the time phase t ₁ and the portal vein Is generated.

Then, the image processing unit 53, by performing image processing such as volume rendering for the synthesis data 431, and generates medical image data such as three-dimensional image data representing the hepatic parenchyma and portal in time phase t ₁ . The medical image data is output to the display unit 81, the screen of the display unit 81, a medical image such as a three-dimensional image representing the hepatic parenchyma and portal in time phase t ₁ is displayed.

Next, a case where data of different parts acquired at different time phases is synthesized will be described. For example, a case where medical image data is generated by synthesizing liver parenchymal data acquired at time phase t ₂ and portal vein data acquired at time phase t ₁ will be described.

Before imaging, information indicating the part (liver parenchyma) extracted from time phase t ₂ , time phase t ₂ volume data, time phase t ₁ , and part (portal vein) extracted from time phase t ₁ volume data Is designated by the operator, information indicating the time phase and part thereof is included in the imaging protocol and stored in the imaging protocol storage unit 7. The area extraction unit 51 stores the volume data 412 acquired at the time phase t ₁ and the volume data 413 acquired at the time phase t ₂ in accordance with the information indicating the time phase and the part included in the imaging protocol. In addition, type data 400 for specifying the liver parenchyma and type data 401 for specifying the portal vein are acquired from the image storage unit 31. In addition, after the start of imaging, when the operator specifies a time phase and a part using the user interface 8, the region extraction unit 51 acquires the volume data 412 and 413 acquired at the specified time phase from the image storage unit 24. Further, the mold data 400 and 401 for specifying the designated part are acquired from the image storage unit 31.

Then, the region extraction unit 51 extracts the liver parenchyma data from the volume data 413 acquired at the time phase t ₂ by using the type data 400 that specifies the liver parenchyma. Volume data 423 obtained by the extraction process, would represent a liver parenchyma in time phase t _2. Further, the region extracting unit 51 extracts portal vein data from the volume data 412 acquired at the time phase t ₁ by using the type data 401 for specifying the portal vein. The volume data 424 obtained by this extraction process represents the liver parenchyma at the time phase t ₁ .

The combining unit 52 generates combined data by combining the volume data extracted by the region extracting unit 51. For example, the synthesis unit 52 synthesizes the volume data 423 representing the liver parenchyma at the time phase t ₂ and the volume data 424 representing the portal vein at the different time phase t ₁ , so that the liver parenchyma and the time phase at the time phase t ₂ are synthesized. Composite data 432 representing the portal vein at t ₁ is generated.

Then, the image processing unit 53, a medical of by performing image processing such as volume rendering for the synthesis data 432, such as three-dimensional image data representing a portal in time phase t ₁ and hepatocyte in time phase t ₂ Generate image data. The medical image data is output to the display unit 81, a medical image such as a three-dimensional image representing a portal in time phase t ₁ and hepatocyte in temporal t ₂ on the screen of the display unit 81 is displayed.

It is also possible to generate the medical image data by combining the data of the hepatic parenchyma and portal in time phase t _2. For example, the region extraction unit 51 extracts portal vein data from the volume data 413 acquired at the time phase t ₂ by using the type data 401 specifying the portal vein. Volume data 425 obtained by the extraction process, would represent a portal in time phase t _2.

Combining unit 52, a volume data 423 representing the hepatic parenchyma in time phase t _2, to synthesize the volume data 425 representing the portal at the same time phase t _2, representing the hepatic parenchyma and portal in time phase t ₂ Generate composite data. Then, the image processing unit 53, by performing image processing such as volume rendering for the combined data to generate the medical image data such as three-dimensional image data representing the hepatic parenchyma and portal in time phase t _2. The medical image data is output to the display unit 81, a medical image such as a three-dimensional image representing the hepatic parenchyma and portal vein in a phase t ₂ when the screen of the display unit 81 is displayed.

(Application example 2 of the image generation unit 5)
Next, another application example (application example 2) of processing by the image generation unit 5 will be described with reference to FIG. FIG. 7 is a schematic diagram for explaining extraction processing of data of a target region.

Here, a case where medical image data of liver parenchyma and artery in a plurality of time phases is generated will be described. For example, when a plurality of time phases (time phase t ₁ , time phase t ₂ , time phase t ₃ ) and a region to be extracted (liver parenchyma and artery) are designated by the operator before imaging, the time phases The information indicating the part is included in the imaging protocol and stored in the imaging protocol storage unit 7. The region extraction unit 51 combines the type data 400 specifying the liver parenchyma and the type data 402 specifying the artery stored in the image storage unit 31 according to the information indicating the time phase and the part included in the imaging protocol. Thus, new type data 403 is generated. This type data 403 represents the shape and position of the liver parenchyma and artery. Then, the region extraction unit 51 uses the new type data 403 to extract liver parenchyma and artery data from the volume data acquired in each time phase.

For example, the region extraction unit 51 acquires volume data 412 acquired at the time phase t ₁ from the image storage unit 24, and extracts data of liver parenchyma and artery by using the type data 403. The volume data 426 obtained by this extraction process represents the liver parenchyma and artery in the time phase t ₁ . Similarly, the region extraction unit 51 acquires the volume data 413 acquired in a time phase t ₂ from the image storage unit 24, by using the type data 403, extracts the data of the hepatic parenchyma and arteries. Volume data 427 obtained by the extraction process, would represent a hepatic parenchyma and artery time phase t _2. The volume data 428 representing the liver parenchyma and artery at the time phase t ₃ is generated by performing extraction processing on the volume data 414 acquired at the time phase t ₃ using the type data 403.

  As described above, by generating and displaying a medical image of a site of interest in each time phase, it is possible to observe a temporal change in contrast at the site of interest. For example, the control unit 6 causes the display unit 81 to sequentially display the medical image of the attention site in each time phase generated by the image processing unit 53 along the time phase, so that the operator recognizes it as a moving image. The progress of contrast can be observed.

  Further, the region extraction unit 51 may acquire time-series volume data from the image storage unit 24, and may extract time-series data of the site of interest by using type data corresponding to the site of interest. The time-series volume data of the site of interest obtained by this extraction processing is output to the display unit 81, and a time-series medical image is displayed on the display unit 81. As a result, the moving image of the site of interest is displayed on the display unit 81.

  The medical image processing unit 3 includes a CPU (not shown) and a storage device such as a ROM, a RAM, and an HDD. The storage device stores an extraction region determination program for executing processing by the extraction region determination unit 4 and an image generation program for executing processing by the image generation unit 5.

  The extraction region determination program for executing processing by the extraction region determination unit 4 includes a reference image acquisition program for executing the function of the reference image acquisition unit 41, a subtraction program for executing the function of the subtraction unit 42, and A type data generation program for executing the function of the type data generation unit 43 is included. In addition, the image generation program for executing the processing by the image generation unit 5 includes a region extraction program for executing the function of the region extraction unit 51, a synthesis program for executing the function of the synthesis unit 52, and an image An image processing program for executing the functions of the processing unit 53 is included.

  Then, the CPU reads the extraction area determination program from the storage device and executes it, thereby executing reference volume data acquisition processing, volume data subtraction processing, and type data generation processing, thereby obtaining a desired part. Generate type data for. Furthermore, the CPU reads the image generation program from the storage device and executes it, thereby executing region extraction processing, volume data synthesis processing, and image processing, thereby generating medical image data of a desired part.

  The user interface (UI) 8 includes a display unit 81 and an input unit 82. The display unit 81 includes a monitor such as a CRT or a liquid crystal display, and displays a three-dimensional image, a tomographic image, or the like on the screen. The input unit 82 includes a pointing device such as a joystick or a trackball, a switch, various buttons, or a keyboard. By using the input unit 82, various settings such as imaging conditions are input, an imaging protocol registered in advance in the medical image diagnostic apparatus 1 is selected, or an area desired to be observed is selected. The shooting conditions input by the input unit 82 are stored in the shooting protocol storage unit 7 as part of the shooting protocol. The control unit 6 controls each unit of the medical image diagnostic apparatus 1 in accordance with the imaging conditions stored in the imaging protocol storage unit 7.

  Here, an example of a method for specifying an imaging protocol including an imaging condition using a user interface (UI) will be described with reference to FIG. FIG. 8 is a diagram showing a shooting protocol setting screen including shooting conditions.

  Before starting a series of shooting, a shooting protocol including shooting conditions is set. For example, as illustrated in FIG. 8A, the control unit 6 causes the display unit 81 to display a list 500 that shows a list of organs that are subject to region extraction. Also, as shown in FIG. 8B, the control unit 6 displays a list of imaging protocols registered in the medical image diagnostic apparatus 1 in advance and stored in the imaging protocol storage unit 7 on the display unit 81. 510 is displayed. The data of the list tables 500 and 510 is stored in the imaging protocol storage unit 7, for example.

  As an example of the list 500 showing organs, the control unit 6 displays representative images (representative images) of the respective organs as thumbnails. The operator refers to the representative image list 500 displayed on the display unit 81 and designates an organ desired to be observed using the input unit 82. For example, when observing the abdominal liver parenchyma, the operator selects a representative image 501 of the liver parenchyma from the list 500.

  Also, by including a representative image in which images of a plurality of parts are combined in the list 500, by specifying the representative image, an image in which the images of the plurality of parts are combined is observed after imaging. can do. For example, the list 500 includes representative images 502 obtained by combining liver parenchyma and portal vein images. When observing the liver parenchyma and portal vein, the operator selects a representative image 502 obtained by combining the liver parenchyma and portal vein images from the list 500.

  Further, in this list 500, the operator can also specify display conditions for displaying images obtained by shooting on the display unit 81. This display condition includes the display color of the image. For example, the control unit 6 colors the liver parenchymal representative image 503 in red, and colors the same liver parenchymal representative image 504 in blue, and causes the display unit 81 to display the list 500.

  As described above, by displaying a representative image of each part or a representative image obtained by synthesizing a plurality of parts on the display unit 81 as a list, the operator can display an image generated by photographing in advance before photographing. It becomes possible to grasp.

  Information indicating the organ to be extracted and selected by the user interface 8 and display conditions are included in the imaging protocol and stored in the imaging protocol storage unit 7.

  The time phase for acquiring the reference volume data used for generating the type data can also be input by the user interface 8, and the input time phase is included in the imaging protocol and stored in the imaging protocol storage unit 7. The

  The list 510 displays a list of standard shooting protocols. Each imaging protocol includes standard imaging conditions (X-ray source current value, voltage value, etc.). The operator can select a desired imaging protocol from the list 510 displayed on the display unit 81, and can change the imaging condition 520 included in the imaging protocol. For example, the range of the shooting area included in the shooting condition 520 can be changed. Further, the prep scan condition and the main scan condition (helical scan condition) are also included in this imaging condition. The photographing protocol selected / edited in the list 510 is stored in the photographing protocol storage unit 7. The medical image acquisition unit 2 performs imaging according to the imaging conditions included in the imaging protocol, and acquires volume data of the imaging area.

  The control unit 6 is connected to each unit of the medical image diagnostic apparatus 1 and controls the operation of the medical image diagnostic apparatus 1. The control unit 6 includes a CPU (not shown) and a storage device such as a ROM, a RAM, and an HDD. The storage device stores a control program for controlling each part of the medical image diagnostic apparatus 1. The CPU controls the operation of the medical image diagnostic apparatus 1 by executing the control program.

  In this embodiment, the medical image diagnostic apparatus 1 has been described as an X-ray CT apparatus. However, in addition to the X-ray CT apparatus, an MRI apparatus, an ultrasonic diagnostic apparatus, an X-ray diagnostic apparatus, or the like has the same effect. And there can be an effect. In the example illustrated in FIG. 1, the configuration of the medical image acquisition unit 2 has been described as the configuration of the X-ray CT apparatus. However, when the medical image diagnostic apparatus 1 is an MRI apparatus, the configuration of the medical image acquisition unit 2 is the same as that of the MRI apparatus. When the configuration is an ultrasonic diagnostic apparatus, the configuration of the medical image acquisition unit 2 is the configuration of the ultrasonic diagnostic apparatus. Thus, even when the configuration of the medical image acquisition unit 2 is changed, the medical image processing unit 3 is a type that represents a desired part from the volume data acquired by the medical image acquisition unit 2 as described above. Data is generated, and further, using the type data, data of a desired part is extracted from volume data acquired at an arbitrary time phase, and medical image data of the part is generated.

  In the example shown in FIG. 1, a medical image processing unit 3 is provided inside the medical image diagnostic apparatus 1 and volume data sent from the medical image acquisition unit 2 is processed. A medical image processing unit 3 may be provided. In this case, the medical image processing unit 3 (medical image diagnostic apparatus) is configured by an information processing apparatus such as a workstation. Then, the medical image diagnostic apparatus excluding the medical image processing unit 3 is connected to the medical image processing unit 3 (medical image processing apparatus) via a network or the like, and the volume data acquired by the medical image diagnostic apparatus is used as the medical image. Transmit to the processing unit 3. As described above, the medical image processing unit 3 installed outside generates type data, extracts data of a desired part, and generates medical image data of the part.

(Operation)
Next, a series of operations by the medical image diagnostic apparatus 1 according to the embodiment of the present invention will be described with reference to FIGS. 9 and 10 are flowcharts showing a series of operations by the medical image diagnostic apparatus according to the embodiment of the present invention. First, with reference to FIG. 9, an operation for obtaining volume data by performing shooting will be described, and then an operation for extracting an area will be described with reference to FIG.

(Step S01)
First, before starting imaging, an imaging protocol including a region extraction target region, imaging conditions, and the like is set. The photographing protocol is stored in the photographing protocol storage unit 7. For example, as shown in FIGS. 8A and 8B, the control unit 6 displays on the display unit 81 a list 500 showing a list of organs to be subjected to image extraction and a list showing a list of imaging protocols. 510 is displayed. The operator designates an organ desired to be observed from the list 500. Here, a case where a medical image of the liver parenchyma and portal vein is observed will be described. In this case, the operator designates a representative image 502 obtained by combining the liver parenchyma and portal vein images among the representative images included in the list 500. Furthermore, the operator can select a desired imaging protocol included in the list 510 and edit the imaging conditions.

(Step S02)
Then, before injecting the contrast medium into the subject, the imaging unit 22 performs imaging under the control of the scan control unit 21. For example, the imaging unit 22 acquires the X-ray projection data of the imaging region 100 by imaging the imaging region 100 shown in FIG. 2, and the image reconstruction unit 23 acquires the imaging region 100 based on the X-ray projection data. Generate volume data. This volume data is stored in the image storage unit 24 as “initial volume data”.

(Step S03)
Then, a contrast medium is injected into the subject, and the imaging unit 22 executes the prep scan under the control of the scan control unit 21, thereby obtaining X-ray projection data at the prep scan imaging position 101 shown in FIG. The image reconstruction unit 23 performs reconstruction processing to generate tomographic image data (monitoring image data). Then, the scan control unit 21 monitors the change in the contrast agent concentration (CT value) in the monitoring ROI 102 set in the monitoring image. Then, the scan control unit 21 compares the CT value threshold set prior to the prep scan with the CT value in the monitoring ROI 102 and determines whether or not the CT value in the monitoring ROI 102 is equal to or greater than the threshold. To do. When the CT value in the monitoring ROI 102 is equal to or greater than the threshold value, the scan control unit 21 causes the imaging unit 22 to stop the prep scan and start the main scan according to the main scan condition.

(Step S04)
In the main scan, the imaging unit 22 performs a helical scan according to the imaging protocol under the control of the scan control unit 21. For example, the imaging unit 22 images the same imaging region 100 shown in FIG. 2 a plurality of times, and performs imaging at a timing when different parts are contrasted. Note that the time point of the start of the main scan (start of photographing) is set to a time phase t ₀ as shown in FIG.

(Step S05)
The image reconstruction unit 23 generates volume data of the imaging region 100 in each time phase based on the X-ray projection data acquired by the imaging unit 22. The volume data in each time phase is stored in the image storage unit 24.

  As described above, while the imaging unit 22 is executing the helical scan, the contrast agent flows into each part, flows away, and flows into other parts, so that the contrast agent flows into each part. Volume data representing the situation can be obtained.

(Step S10)
Then, the reference image acquisition unit 41 in accordance with the imaging protocol, from the time of the scan start (time phase t _0), the volume data acquired at the time the preset time has elapsed, acquires from the image storage unit 24 . For example, as illustrated in FIG. 3, the reference image acquisition unit 41 includes volume data 301 acquired at a time point (time phase t ₁ ) when the concentration (luminance value) of the contrast agent in the artery becomes maximum, and the contrast agent in the pancreatic parenchyma. Volume data 302 acquired at the time when the density (luminance value) of the liver becomes maximum (time phase t ₂ ) and at the time when the concentration (luminance value) of the contrast agent in the liver parenchyma becomes maximum (time phase t ₃ ). The acquired volume data 303 is acquired from the image storage unit 24. These volume data are data in which the contrast agent flows into different parts, and the luminance values (CT values) of the different parts are high. These volume data are respectively referred to as “reference volume data”.

(Step S11)
Next, the subtraction unit 42 acquires volume data (initial volume data) acquired before injecting the contrast medium into the subject from the image storage unit 24, and the reference of each part acquired by the reference image acquisition unit 41. The initial volume data is subtracted from the volume data (first subtraction process). As a result of this subtraction process, data representing the region (the region of interest) into which the contrast agent flows is left in the first subtraction volume data after the subtraction. With this first subtracted volume data, it is possible to specify the site where the contrast agent is injected.

  For example, as shown in FIG. 4, the subtracting unit 42 subtracts the initial volume data 300 from the reference volume data 301 to generate first subtracted volume data 310 after subtraction. In the first subtraction volume data 310, a portion having a relatively high voxel value represents an artery. Similarly, the subtraction unit 42 generates the first subtraction volume data 311 after subtraction by subtracting the initial volume data 300 from the reference volume data 302 and subtracts the initial volume data 300 from the reference volume data 303. First subtracted volume data after subtraction is generated. The first subtraction volume data generated by the subtraction unit 42 is stored in the image storage unit 31 installed in the medical image processing unit 3.

Furthermore, from the volume data 302 acquired in time phase t _2, to remove the portion contrast to time phase t ₂ previously, subtraction unit 42, as shown in FIG. 4, the first subtraction volume data 311, The first subtraction volume data 310 is subtracted (second subtraction process). By subtracting the first subtraction volume data 310 representing the artery from the first subtraction volume data 311 including the artery and pancreatic parenchyma, the second subtraction volume data generated as a result of the subtraction process includes Only will be left. The second subtraction volume data generated by the subtraction unit 42 is stored in the image storage unit 31 installed in the medical image processing unit 3. As described above, in order to remove the portion contrasted before the predetermined time phase from the volume data acquired at the predetermined time phase, the subtracting unit 42 uses the reference volume data acquired at the predetermined time phase. By subtracting the first subtracted volume data generated from the volume data acquired before the predetermined time phase from the generated first subtracted volume data, the second subtracted volume data at the predetermined time phase is generated. To do.

(Step S12)
Then, the type data generation unit 43 reads the first subtraction volume data or the second subtraction volume data generated as a result of the subtraction process by the subtraction unit 42 from the image storage unit 31, and performs a binarization process, for example. Type data representing the shape and position of the part included in the first subtraction volume data or the second subtraction volume data is generated. By this binarization processing, the value of the region where the contrast agent flows in and the voxel value (luminance value) is high is converted to “1”, and the values of the other regions are converted to “0”. become. This type data is stored in the image storage unit 31 installed in the medical image processing unit 3.

(Step S13)
When the type data is generated as described above, the region extraction unit 51 acquires the volume data acquired in the time phase designated by the operator from the image storage unit 24. For example, when the time phase t ₁ is designated as the time phase for performing the region extraction, the region extracting unit 51 acquires the volume data acquired at the time phase t ₁ from the image storage unit 24.

(Step S14)
Then, the region extraction unit 51 acquires type data specifying a part included in a preset imaging protocol from the image storage unit 31, and acquires the time data designated by the operator by using the type data. The data of the area specified by the type data is extracted from the obtained volume data. For example, when the liver parenchyma and portal vein are designated as the extraction region, as shown in FIG. 6, the region extraction unit 51 calculates the shape of the liver parenchyma from the volume data 412 acquired at the time phase t _1. By using the type data 400 representing the position, volume data 422 representing the liver parenchyma is generated. Further, the region extraction unit 51 generates volume data 424 representing the portal vein by using the type data 401 representing the shape and position of the portal vein from the volume data 412 acquired at the time phase t ₁ .

(Step S15)
The synthesizer 52 synthesizes a plurality of volume data output from the area extractor 51 to generate synthesized data. For example, as illustrated in FIG. 6, the combining unit 52 generates combined data 431 by combining volume data 422 representing the liver parenchyma and volume data 424 representing the portal vein.

(Step S16)
The image processing unit 53 receives the synthesized data output from the synthesizing unit 52 and performs image processing such as volume rendering and MPR processing on the synthesized data, thereby obtaining a medical image such as three-dimensional image data or MPR image data. Generate data. For example, the image processing unit 53 performs volume rendering on the composite data 431 to generate three-dimensional image data in which the liver parenchyma and portal vein are represented.

(Step S17)
Medical image data such as three-dimensional image data generated by the image processing unit 53 is output to the display unit 81, and an image based on the medical image data is displayed on the screen of the display unit 81. For example, when volume data 422 representing the liver parenchyma and volume data 424 representing the portal vein are synthesized, a three-dimensional image representing the liver parenchyma and portal vein is displayed on the screen of the display unit 81.

  In this embodiment, the combining unit 52 combines a plurality of volume data, and the image processing unit 53 generates medical image data based on the combined data generated by the combining. Medical image data may be generated by performing image processing on the volume data before synthesis processing extracted by the extraction unit 51. Thereby, for example, a three-dimensional image of the liver parenchyma and a three-dimensional image of the portal vein are displayed on the display unit 81.

  As described above, by using the time for the contrast medium to flow into each part, type data representing the shape and position of each part is generated, and using the type data, the volume acquired at an arbitrary time phase Data of each part can be easily extracted from the data. Furthermore, by combining the data of different parts, it is possible to generate and display medical image data representing a plurality of parts.

  Further, after imaging, an image of a part desired to be observed can be freely changed. For example, after imaging, the control unit 6 causes the display unit 81 to display a list 500 of organs to be subjected to region extraction, and the operator designates a desired part from the list 500 and further performs observation. Specify the desired time phase. When the part and time phase are specified by the operator, the image extraction unit 51 acquires the volume data acquired at the time phase specified by the operator from the image storage unit 24, and the part of the part specified by the operator is acquired. The mold data representing the shape and position is acquired from the image storage unit 31, and the data of the part is extracted from the volume data by using the mold data. Then, the image processing unit 53 performs predetermined image processing on the extracted volume data, thereby generating medical image data such as three-dimensional image data representing the extracted part. In addition, the operator can designate a part of the part displayed on the display unit 81 and hide the part.

  Further, the control unit 6 may obtain the flow rate of the contrast agent based on the plurality of medical image data acquired by the medical image acquisition unit 2, and may determine the blood flow velocity based on the speed.

1 is a block diagram showing a schematic configuration of a medical image diagnostic apparatus according to an embodiment of the present invention. It is a figure which shows the three-dimensional space for demonstrating a three-dimensional imaging | photography area | region. It is a figure which shows the timing of imaging | photography, and the density | concentration (luminance value) of a contrast agent. It is a schematic diagram for demonstrating the subtraction process with respect to volume data. It is a schematic diagram for demonstrating the extraction process of the data of an attention site | part. It is a schematic diagram for demonstrating the extraction process of the data of an attention site | part. It is a schematic diagram for demonstrating the extraction process of the data of an attention site | part. It is a figure which shows the setting screen of the imaging protocol containing imaging conditions. It is a flowchart which shows a series of operation | movement by the medical image diagnostic apparatus which concerns on embodiment of this invention. It is a flowchart which shows a series of operation | movement by the medical image diagnostic apparatus which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Medical image diagnostic apparatus 2 Medical image acquisition part 3 Medical image processing part 4 Extraction area | region determination part 5 Image generation part 6 Control part 7 Imaging protocol memory | storage part 8 User interface 21 Scan control part 22 Imaging part 23 Image reconstruction part 24, 31 Image storage unit 41 Reference image acquisition unit 42 Subtraction unit 43 Type data generation unit 51 Area extraction unit 52 Composition unit 53 Image processing unit

Claims (13)

Medical image acquisition means for acquiring a plurality of volume data by imaging a predetermined imaging region of the subject at a plurality of time points after a predetermined time has elapsed after the contrast agent is injected into the subject;
Subtracting means for generating first subtracted volume data by subtracting initial volume data from each of the volume data acquired at a plurality of time points after the contrast agent is injected into the subject;
Region extraction means for extracting data of a site into which the contrast agent specified by the first subtraction volume data flows from the volume data acquired by the medical image acquisition means;
Combining means for combining the plurality of extracted data to generate combined data;
A medical image diagnostic apparatus comprising: Before the contrast agent is injected into the subject, initial volume data is acquired by imaging a predetermined imaging region of the subject, and further, the contrast agent is preset after the contrast agent is injected into the subject. Medical image acquisition means for acquiring a plurality of volume data by imaging a predetermined imaging region of the subject at a plurality of time points when the predetermined time has passed ,
Subtracting means for generating first subtracted volume data at each time point by subtracting the initial volume data from each of the volume data acquired at a plurality of time points after the contrast agent is injected into the subject;
Region extraction means for extracting data of a portion into which the contrast agent specified by the first subtraction volume data at each time point is extracted from the volume data acquired at any time by the medical image acquisition means;
Combining means for combining the plurality of extracted data to generate combined data;
Display means for displaying a medical image based on the composite data;
A medical image diagnostic apparatus comprising: The time in which the concentration of contrast agent in the contrast medium flows from the injection into the subject at the predetermined site contrast agent is substantially maximum, to claim 2, characterized in that it is set as the predetermined time The medical image diagnostic apparatus described. The subtracting means subtracts the initial volume data from the volume data acquired when a first time has elapsed after the contrast agent has been injected into the subject. First subtracted volume data is generated, and after the contrast agent is injected into the subject, the initial volume data is obtained from the volume data acquired when a second time later than the first time has elapsed. Subtracting generates first subtracted volume data at the second time, and further subtracts the first subtracted volume data at the first time from the first subtracted volume data at the second time. And generating second subtracted volume data at the second time,
Area extraction means, claim 2 or claim, characterized in that said from the volume data acquired at any time by the medical image obtaining unit extracts the data portion specified by the second subtraction volume data the medical image diagnostic apparatus according to 3. There is further provided type data generation means for generating type data representing the shape and position of the portion where the contrast agent has flowed in when the predetermined time has elapsed by performing binarization processing on the first subtraction volume data. And
The said area extraction means extracts the data of the site | part specified by the said type | mold data from the volume data acquired at the arbitrary times by the said medical image acquisition means, The Claim 2 or Claim 3 characterized by the above-mentioned. Medical image diagnostic equipment. The region extraction unit extracts time-series data of a part specified by the first subtraction volume data from the time-series volume data acquired by the medical image acquisition unit,
The medical image diagnosis apparatus according to claim 2 , wherein the display unit displays a medical image based on the extracted time-series data. The region extraction unit extracts time-series data of a part specified by the type data from the time-series volume data acquired by the medical image acquisition unit,
The medical image diagnostic apparatus according to claim 5 , wherein the display unit displays a medical image based on the extracted time-series data. After the contrast agent is injected into the subject, the contrast agent is detected from each of the volume data acquired by imaging a predetermined region of the subject at a plurality of time points after a predetermined time has elapsed. Subtracting means for generating first subtracted volume data at each time point by subtracting the initial volume data acquired by imaging the predetermined imaging area before being injected into the specimen;
A region extracting means for extracting data of a portion into which the contrast agent specified by the first subtracted volume data at each time point is extracted from volume data acquired by imaging a predetermined region of the subject;
Combining means for combining the plurality of extracted data to generate combined data ;
Display means for displaying a medical image based on the composite data;
A medical image processing apparatus comprising: The time in which the concentration of contrast agent in the contrast medium flows from the injection into the subject at the predetermined site contrast agent is substantially maximum, to claim 8, characterized in that it is set as the predetermined time The medical image processing apparatus described. The subtracting means subtracts the initial volume data from the volume data acquired when a first time has elapsed after the contrast agent has been injected into the subject. First subtracted volume data is generated, and after the contrast agent is injected into the subject, the initial volume data is obtained from the volume data acquired when a second time later than the first time has elapsed. Subtracting generates first subtracted volume data at the second time, and further subtracts the first subtracted volume data at the first time from the first subtracted volume data at the second time. And generating second subtracted volume data at the second time,
The medical image according to claim 8 or 9 , wherein the region extraction unit extracts data of a part specified by the second subtracted volume data from volume data acquired at an arbitrary time point. Processing equipment. There is further provided type data generation means for generating type data representing the shape and position of the portion where the contrast agent has flowed in when the predetermined time has elapsed by performing binarization processing on the first subtraction volume data. And
The medical image according to any one of claims 8 to 10 , wherein the region extraction unit extracts data of a part specified by the type data from volume data acquired at an arbitrary time point. Processing equipment. The region extracting means extracts time-series data of a part specified by the first subtracted volume data from time-series volume data,
The medical image processing apparatus according to any one of claims 8 to 10 , wherein the display unit displays a medical image based on the extracted time-series data. The region extraction means extracts time-series data of a part specified by the type data from time-series volume data,
The medical image processing apparatus according to claim 11 , wherein the display unit displays a medical image based on the extracted time-series data.

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