JP2014050536A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an improved technology in blood vessel diagnosis using an ultrasonic diagnostic apparatus.SOLUTION: A B-mode image forming part 20 forms B-mode image data including a long axis view of a blood vessel. A storage image selection part 30 stores the B-mode image data while a subject is in a resting state and the B-mode image data in a maximum diameter period that includes a blood vessel diameter becoming the maximum after an avascularization state, in a data storage part 50. The data storage part 50 stores biosignal data along with the B-mode image data, and an R-wave time phase extraction part 60 refers to the biosignal data to select the B-mode image data corresponding to a time phase of an R wave from the B-mode image data in multiple time phases that is stored in the data storage part 50. A display image forming part 80 forms a display image relating to vascular endothelium function evaluation by FMD, on the basis of multiple pieces of the B-mode image data corresponding to the time phase of the R wave.

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus suitable for blood vessel diagnosis.

  Blood flow responsive dilatation (FMD) is known as a method for blood vessel diagnosis using an ultrasonic diagnostic apparatus, for example, vascular endothelial function evaluation (see, for example, Patent Documents 1 and 2).

  Vascular endothelial function measurement by FMD is considered useful for evaluation of endothelial function of blood vessels and evaluation of arteriosclerosis. The measurement procedure is as follows, for example. First, the diameter of the brachial artery is measured when the subject is at rest, and then the forearm portion of the subject is driven with a cuff or the like for about 5 minutes. Thereafter, when the tourniquet is released, the blood vessel diameter of the brachial artery is expanded and gradually returns to the blood vessel diameter at rest. Then, the endothelial function of the brachial artery is evaluated from the change in the diameter of the blood vessel after the release of blood pressure and the state of the blood vessel at rest.

  In the evaluation of vascular endothelial function by FMD, an ultrasonic diagnostic apparatus is used for measuring a blood vessel diameter. For example, the echo tracking process of the ultrasonic diagnostic apparatus tracks the position of the blood vessel wall at rest, during blood excitement, and after release of blood transfusion. It is formed.

JP 2007-267777 A Japanese Patent Application Laid-Open No. 2004-129997

  In the evaluation of vascular endothelial function by FMD, the blood vessel diameter is continuously measured for about 10 minutes from resting to after the release of blood transfusion. For the measurement, line data obtained along the ultrasonic beam at the measurement position is used, and the blood vessel diameter is calculated based on the position of the blood vessel wall tracked in the line data. Therefore, for example, the position of the blood vessel wall is tracked in the line data for a long time of about 10 minutes, and the line data obtained for the long time is stored in a memory or the like.

  However, the time phase in which the value of the vascular diameter is required in the evaluation of vascular endothelial function by FMD is limited to a part of a long period of about 10 minutes and is stored for a long time. Most of the line data was deemed unnecessary. Further, since the diagnosis is performed for a long time, the data capacity of image data such as a B-mode image obtained during the diagnosis period is enormous, and it is difficult to store the image data in a storage device or the like.

  Against such a background, the inventors of the present application have conducted research and development on blood vessel diagnosis using an ultrasonic diagnostic apparatus, for example, evaluation of vascular endothelial function.

  The present invention has been made in the course of its research and development, and an object thereof is to provide an improved technique for diagnosing blood vessels using an ultrasonic diagnostic apparatus.

  An ultrasonic diagnostic apparatus suitable for the above object includes a probe that transmits and receives ultrasonic waves, a transmission / reception unit that obtains a reception signal from a diagnostic region including a blood vessel in a living body by controlling transmission of the probe, and a plurality of ultrasonic diagnostic devices within a diagnostic period. Based on received signals obtained over time phases, an image data forming unit that forms image data of a diagnostic region for each time phase, and image data of a plurality of time phases within an attention period selected within the diagnosis period A biometric signal data obtained by measuring in-vivo pulsations, a data storage unit, and a plurality of time-phase image data within a period of interest, based on the bio-signal data. Obtained based on a specific time phase extraction unit that extracts image data of a specific time phase within a dynamic cycle, a blood vessel wall specification unit that specifies the position of a blood vessel wall in the image data of the specific time phase, and the position of the blood vessel wall Blood vessels And having a display image forming unit for forming a display image.

  According to the ultrasonic diagnostic apparatus, since the blood vessel wall specifying unit specifies the position of the blood vessel wall in the image data, it is not necessary to track the position of the blood vessel wall over a plurality of continuous time phases, for example. For this reason, it is possible to selectively store the image data in the attention period without storing all the image data in the diagnosis period.

  In a preferred embodiment, the display image forming unit forms a display image including an A mode waveform corresponding to a line designated in image data of a specific time phase.

  In a preferred embodiment, the display image forming unit forms a display image including an M mode image in which line images obtained from lines designated in image data of a specific time phase are arranged over a plurality of time phases. It is characterized by.

  In a preferred embodiment, the display image forming unit displays a marker indicating the position of the blood vessel wall specified by the blood vessel wall specifying unit in the M-mode image.

  In a desirable specific example, the display image forming unit forms a display image including a change waveform of the blood vessel diameter along the time axis direction of the M mode image with respect to the blood vessel diameter calculated based on the position of the blood vessel wall. The time axis of the blood vessel diameter change waveform and the time axis of the M-mode image are displayed in alignment.

  In a preferred embodiment, the display image forming unit changes the blood flow velocity or blood flow volume along the time axis direction of the M-mode image with respect to the blood flow velocity or blood flow volume obtained based on intra-vascular Doppler information. Is formed, and the time axis of the blood flow velocity or blood flow change waveform is aligned with the time axis of the M-mode image.

  In a preferred embodiment, the blood vessel wall specifying unit specifies a lumen region corresponding to the lumen of the blood vessel in the image data, and based on a change in a pixel value from the lumen region toward the outside of the blood vessel, A membrane is specified, and the position of the intima is set as the position of the blood vessel wall.

  According to the present invention, an improved technique for diagnosing blood vessels using an ultrasonic diagnostic apparatus is provided.

1 is an overall configuration diagram of an ultrasonic diagnostic apparatus suitable for implementing the present invention. It is a figure for demonstrating selection of the diagnostic period and attention period in FMD. It is a figure for demonstrating extraction of the B mode image data of R wave time phase. It is a figure which shows the specific example of a B mode image and an A mode waveform. It is a figure which shows the specific example of an M mode image. It is a figure which shows the specific example of the display image which concerns on the vascular endothelial function evaluation by FMD. It is a conceptual diagram of the pixel group which one frame data shows. It is a conceptual diagram of the frame data image to which the mask process was performed. It is a figure which shows a mask upper end pixel and a mask lower end pixel. It is a figure for demonstrating the process which calculates | requires the outline of the front wall side of a lumen | bore area | region. It is a flowchart which shows the process which calculates | requires the outline of the front wall side of a lumen | bore area | region. It is a figure which shows a front wall outline pixel group and a back wall outline pixel group. It is a conceptual diagram which shows distribution of the pixel value in one line image. It is a figure for demonstrating the process which searches an intima point.

  FIG. 1 is an overall configuration diagram of an ultrasonic diagnostic apparatus (present ultrasonic diagnostic apparatus) suitable for implementing the present invention. The probe 10 is an ultrasonic probe that transmits and receives ultrasonic waves, and scans an ultrasonic beam in a diagnostic region including blood vessels in a subject (living body). In this ultrasonic diagnostic apparatus, the probe 10 is preferably a linear probe, for example, and moves the ultrasonic beam along the long axis direction of the blood vessel by electronic scanning. Note that a probe 10 having a scanning mode different from that of the linear probe may be used, or a probe 10 that three-dimensionally scans an ultrasonic beam within a diagnostic region by electronic scanning or a combination of electronic scanning and mechanical scanning. It may be used.

  The transmission / reception unit 12 controls transmission of a plurality of vibration elements included in the probe 10 to form a transmission beam, and scans the transmission beam within the diagnostic region. In addition, the transmission / reception unit 12 forms a reception beam by performing phasing addition processing on a plurality of reception signals obtained from the plurality of vibration elements, and collects reception signals from the entire diagnosis area. That is, the transmission / reception unit 12 has functions of a transmission beamformer and a reception beamformer.

  The B-mode image forming unit 20 forms B-mode image (tomographic image) data of the diagnostic region based on the received signals collected from within the diagnostic region. That is, image data of a tomographic image including the long-axis cross section of the blood vessel is formed.

  In addition to B-mode image data of a tomographic image including a long-axis cross section of a blood vessel, Doppler information in the tomographic image may be obtained. Then, Doppler image data representing the speed at each point in the tomographic image may be formed.

  This ultrasonic diagnostic apparatus has a function suitable for evaluating vascular endothelial function by blood flow responsive dilatation (FMD). In the evaluation of vascular endothelial function by FMD, the B-mode image forming unit 20 performs B-mode image data for each time phase over a plurality of time phases within a diagnosis period of about 10 minutes from resting to after release of blood transfusion. Form.

  The B mode image data formed in the B mode image forming unit 20 is sent to the display image forming unit 80, and an image corresponding to the B mode image data is displayed on the display unit 90. That is, a B-mode image having a plurality of time phases within a diagnosis period from resting to after cancellation of blood transfusion, that is, a moving image related to a tomographic image of blood vessels is displayed on the display unit 90.

  Further, the B mode image data formed in the B mode image forming unit 20 is sent to the stored image selecting unit 30. The stored image selection unit 30 stores B-mode image data of a plurality of time phases within the attention period selected within the diagnosis period in accordance with the operation of the user (examiner) input via the operation device 40. 50. The data storage unit 50 is a storage device such as a hard disk or a semiconductor memory.

  FIG. 2 is a diagram for explaining selection of a diagnosis period and an attention period in FMD. FIG. 2 shows changes in blood vessel diameter during diagnosis of FMD. The horizontal axis represents the diagnosis time (measurement time), and the vertical axis represents the blood vessel diameter.

  In FMD diagnosis using this ultrasonic diagnostic apparatus, for example, a blood vessel of the brachial artery is a diagnosis target, and B-mode image data of the blood vessel is formed from the resting state of the subject. In FIG. 2, period I is a resting state.

  Next, the forearm of the subject is driven with a cuff or the like. In FIG. 2, the period II is a blood-feeding state. The blood vessel diameter gradually decreases immediately after the blood transfusion, and then maintains a substantially constant value. For example, the blood drive is performed for about 5 minutes. B-mode image data of blood vessels is also formed in period II of the blood-feeding state.

  Then, the cuff is released after the blood-feeding state. In FIG. 2, period III is a period after the cuff is released. When the cuff is released, the blood vessel diameter starts to increase from about time T1 when, for example, about 30 to 40 seconds have passed since the opening. After the blood vessel diameter reaches the maximum value, it gradually decreases and returns to the resting state. B-mode image data of the blood vessel is also formed in the period III after the cuff is released.

  In this ultrasonic diagnostic apparatus, blood vessel B-mode image data is formed for each time phase over the entire period from period I to period III, and a moving image relating to a tomographic image of the blood vessel is displayed on the display unit 90 (FIG. 1). Is displayed.

Furthermore, this ultrasonic diagnostic apparatus calculates% FMD (percent FMD) as the FMD diagnosis result. % FMD is calculated by the following equation.
(Expression 1)% FMD = ((maximum diameter after opening−diameter at rest) / diameter at rest) × 100
That is, in calculating% FMD, a resting diameter that is a blood vessel diameter at rest and a maximum post-opening diameter that is the maximum value of the blood vessel diameter after the cuff is opened are required.

  Therefore, the present ultrasonic diagnostic apparatus has a maximum blood vessel diameter in the period I of about 10 heartbeats in the period I in the resting state and the period III after the cuff release in the entire diagnosis period from the period I to the period III shown in FIG. The B-mode image data of a plurality of time phases within the attention period is stored in the data storage unit 50 (FIG. 1).

  Returning to FIG. 1, the B-mode image data of the attention period is selected by the stored image selection unit 30. The stored image selection unit 30 stores B-mode image data of a plurality of time phases in the attention period in the data storage unit 50 in accordance with a user (examiner) operation input via the operation device 40.

  In FMD diagnosis, the examiner first operates the operation device 40 in a resting state of the subject, and inputs an instruction to store B-mode image data of a plurality of time phases in the resting state. In response to this operation, the stored image selection unit 30 stores, for example, B-mode image data for a preset recording time (for example, about 10 seconds) in the data storage unit 50.

  As will be described later, since the biological signal data that is the measurement result of the pulsation (heartbeat) in the subject has been obtained, the stored image selection unit 30 refers to the biological signal data, for example, in advance. You may make it memorize | store the B mode image data of the set heart rate (for example, about 10 heartbeats) in the data storage part 50. FIG.

  After the diagnosis in the resting state, the forearm of the subject is driven with a cuff or the like, and the diagnosis in the period II is performed (see FIG. 2). However, in calculating% FMD, since the blood vessel diameter in the period II is not necessary, the B-mode image data of period II need not be stored in the data storage unit 50. Of course, the B mode image data in the period II may be stored in the data storage unit 50 as reference data.

  When the cuff is released after the blood pumping state, the examiner looks at the moving image related to the B-mode image, that is, the tomographic image of the blood vessel, displayed on the display unit 90, for example, at the timing when the blood vessel diameter becomes maximum. To input an instruction to store B-mode image data of a plurality of time phases in a period including the maximum blood vessel diameter (maximum diameter period). In response to this operation, the stored image selection unit 30 stores, for example, B-mode image data for a period retroactive from the operation timing for a preset recording time (for example, about several tens of seconds or several tens of heartbeats). Store in the storage unit 50.

  That is, since the user operates at the timing immediately after confirming the maximum diameter in the moving image, the B-mode image data is stored so that the maximum diameter is included by going back several tens of seconds from that timing. Of course, in addition to the B-mode image data temporally preceding the user operation timing, the B-mode image data temporally subsequent to the timing may be stored, for example, for several tens of seconds.

  Further, the B-mode image data in the release period including the time T1 (see FIG. 2) at which the cuff is released after the blood pumping state and the blood vessel diameter starts to expand may be stored in the data storage unit 50.

  In this way, this ultrasonic diagnostic apparatus selects the minimum B-mode image data required for FMD diagnosis within a long-term diagnosis period of about 10 minutes from resting to after release of blood transfusion. The data is stored in the data storage unit 50. Therefore, the storage capacity of the data storage unit 50 can be significantly reduced as compared to storing all B-mode image data during the diagnosis period. In addition, since the minimum B-mode image data required for FMD diagnosis is selected, the load on the subsequent processing using the data stored in the data storage unit 50 is also reduced.

  The data storage unit 50 also stores biological signal data that is a measurement result of pulsation (heartbeat) in the subject. For example, biosignal data such as an electrocardiographic waveform measured by an electrocardiograph is stored. The biological signal data is stored in association with the B-mode image data. That is, the B-mode image data obtained and stored for each time phase is associated with the time phase of the B-mode image data and the time phase of the bio-signal data, and the bio-signal data together with the B-mode image data is stored. It is stored in the data storage unit 50.

  The R-wave time phase extraction unit 60 refers to biological signal data associated with the B-mode image data of each time phase from among the B-mode image data of a plurality of time phases stored in the data storage unit 50, B-mode image data corresponding to the time phase of the R wave of the biological signal data is selected. The blood vessel diameter changes within one heartbeat due to the influence of pulsation. That is, in addition to the macroscopic change shown in FIG. 2, the blood vessel diameter periodically changes due to the influence of pulsation when viewed microscopically. Therefore, in order to reduce or eliminate the influence of pulsation in the evaluation of the blood vessel diameter, B-mode image data corresponding to the R-wave time phase is selected by the R-wave time phase extraction unit 60.

  FIG. 3 is a diagram for explaining extraction of B-mode image data in the R-wave time phase. FIG. 3 shows a specific example of B-mode image data (symbol B) stored in the data storage unit 50. That is, B-mode image data of a plurality of time phases in a resting period in a resting state, an opening period immediately after opening the cuff, and a maximum diameter period including a maximum blood vessel diameter are shown. The B-mode image data is stored, for example, in the order of acquisition, that is, in order of time phase.

  The R wave time phase extraction unit 60 selects B mode image data corresponding to the R wave time phase from among a plurality of time phase B mode image data stored in the data storage unit 50. That is, a plurality of B-mode image data indicated as “R wave” in FIG. Then, a plurality of B-mode image data corresponding to the time phase of the R wave obtained from the rest period, the open period, and the maximum diameter period are sequentially sent to the blood vessel wall specifying unit 70, for example, in time phase order.

  When Doppler image data is formed, the Doppler image data corresponding to each B-mode image data as well as a plurality of B-mode image data corresponding to the time phase of the R wave are also passed through the blood vessel wall specifying unit 70. To the display image forming unit 80.

  Returning to FIG. 1, the blood vessel wall specifying unit 70 specifies the position of the blood vessel wall in each B-mode image data corresponding to the time phase of the R wave. The blood vessel wall specifying unit 70 specifies the lumen region corresponding to the lumen of the blood vessel in each B-mode image data, and specifies the intima of the blood vessel based on the change in the pixel value from the lumen region toward the outside of the blood vessel. The position of the intima is taken as the position of the blood vessel wall. The process of specifying the position of the blood vessel wall (intima) by the blood vessel wall specifying unit 70 will be described in detail later with reference to FIGS. Each B-mode image data in which the position of the blood vessel wall is specified by the blood vessel wall specifying unit 70, that is, a plurality of B-mode image data corresponding to the time phase of the R wave is sent to the display image forming unit 80.

  The display image forming unit 80 forms a display image related to measurement of the blood vessel diameter, particularly a display image related to evaluation of vascular endothelial function by FMD, based on a plurality of B-mode image data corresponding to the time phase of the R wave. The display image forming unit 80 includes a B-mode image, an A-mode waveform, an M-mode image, a blood vessel diameter change waveform, a calculation result of% FMD (percent FMD), and the like as display images related to vascular endothelial function evaluation by FMD. Form an image. The display image formed in the display image forming unit 80 is displayed on the display unit 90 configured by a display device such as a monitor.

  FIG. 4 is a diagram illustrating a specific example of a B-mode image and an A-mode waveform. The B mode image in FIG. 4 is an image corresponding to B mode image data corresponding to the time phase of the R wave, and a long-axis cross section of the blood vessel is displayed in the B mode image. Of a plurality of B-mode images corresponding to the time phase of the R wave, for example, a B-mode image at a time phase designated by the user (inspector) is displayed. Of course, B-mode images of a plurality of time phases may be displayed one after another, for example, in order of time phases.

  The A mode waveform is a waveform indicating a change in the luminance value in the depth direction on the line L specified in the B mode image. For example, the user sets a line L at a desired position in the B-mode image, and an A-mode waveform corresponding to the line L is formed. The line L may be associated with one pixel column, and the A mode waveform may indicate a change in luminance value along the one pixel column, or the line L may be associated with a plurality of pixel columns. The mode waveform may indicate a change in average value of luminance values obtained from the plurality of pixel columns.

  Further, a blood vessel wall marker m indicating the position of the blood vessel wall specified by the blood vessel wall specifying unit 70 (FIG. 1) may be displayed in the A mode waveform. The blood vessel wall is specified for each of the shallow front wall and the deep rear wall, and two blood vessel wall markers m corresponding to the front wall and the rear wall are displayed in the A-mode waveform. The distance between these two blood vessel wall markers m is the blood vessel diameter.

  FIG. 5 is a diagram illustrating a specific example of an M-mode image. In forming an M-mode image, a line image obtained from a line L (see FIG. 4) designated in B-mode image data is used. The M-mode image is an image in which line images obtained from the line L are arranged along the time axis direction over a plurality of time phases.

  That is, the line image obtained from each of a plurality of B-mode image data sequentially extracted in the order of time phase 1, time phase 2, time phase 3,... By the R wave time phase extraction unit 60 (FIG. 1). Based on this, an M-mode image is formed.

  In addition, you may display the blood vessel wall marker m which shows the position of the blood vessel wall specified in the blood vessel wall specific | specification part 70 (FIG. 1) in an M mode image. For example, as shown in FIG. 5, two blood vessel wall markers m corresponding to the front wall and the rear wall are displayed in the M-mode image.

  FIG. 6 is a diagram showing a specific example of a display image relating to vascular endothelial function evaluation by FMD. The display image shown in FIG. 6 includes a B mode image (B), an A mode waveform (A), an M mode image (M), a blood vessel diameter change waveform (D), and a blood flow velocity change waveform (V).

  A specific example of the B mode image and the A mode waveform is as described with reference to FIG. 4, and a specific example of the M mode image is as described with reference to FIG. The blood vessel diameter change waveform shown in FIG. 6 is a waveform showing the time change of the blood vessel diameter calculated based on the position of the blood vessel wall specified by the blood vessel wall specifying unit 70 (FIG. 1). That is, a blood vessel diameter change waveform is a blood vessel diameter calculated for each time phase with the horizontal axis as a time axis and the vertical axis as a blood vessel diameter value.

  The time axis of the blood vessel diameter change waveform and the time axis of the M-mode image are displayed in alignment with each other. Further, the time phase cursor T may be displayed in a specific time phase in the blood vessel diameter change waveform and the M-mode image, for example, in a time phase in which the blood vessel diameter becomes maximum. Of course, a cursor indicating the time phase at which the blood vessel diameter is minimum or the time phase at rest may be displayed.

  Furthermore, the calculation result of% FMD (percent FMD), the value of the blood vessel diameter, and the like are also displayed in the display image. The value of% FMD (10.7%) has already been explained based on the resting diameter that is the blood vessel diameter at rest and the maximum diameter after opening that is the maximum value of the blood vessel diameter after opening the cuff (Equation 1 ).

  As the blood vessel diameter, for example, the blood vessel diameter at rest (3.92 mm) and the maximum blood vessel diameter (4.34 mm) are displayed. Moreover, the difference value (0.42 mm) of the blood vessel diameter between the maximum time and the rest time may be displayed.

  When Doppler image data is obtained, the blood flow velocity and blood flow volume in the blood vessel may be calculated based on the Doppler image data. For the calculation of the blood flow velocity and the blood flow volume, it is desirable to use, for example, a technique described in a reference document (Japanese Patent Laid-Open No. 9-248304).

  For example, on the line L (see FIG. 4) designated in the B-mode image, the velocity in the direction orthogonal to the line L is determined based on Doppler information at a plurality of points between the blood vessel walls, that is, within the blood vessel. Calculate and use the average value of the velocity at multiple points as the blood flow velocity. In addition, the blood flow rate is calculated from the blood flow velocity, which is an average value of the velocities at a plurality of points, and the blood vessel diameter, which is the distance between the blood vessel wall.

  The blood flow rate change waveform shown in FIG. 6 is a waveform showing the time change of the blood flow rate. In other words, the blood flow rate change waveform indicates the blood flow rate calculated for each time phase with the horizontal axis as the time axis and the vertical axis as the blood flow rate value. Instead of the blood flow rate change waveform or together with the blood flow rate change waveform, a blood flow rate change waveform may be displayed.

  The time axis of the blood flow velocity change waveform, the time axis of the blood vessel diameter change waveform, and the time axis of the M-mode image are displayed in alignment with each other. In addition, the time phase cursor T may be displayed in a specific time phase, for example, the time phase where the blood vessel diameter becomes maximum or the time phase where the blood flow velocity becomes maximum.

Further, in the display image,% Vel. The calculation result of (Percent Vel.) And the value of the blood flow rate are also displayed. % Vel. The value of (124.4%) is based on the blood flow rate at rest (resting blood flow rate) and the maximum blood flow rate that is the maximum value of the blood flow rate after opening the cuff, for example, by the following equation: Calculated.
% Vel. = ((Maximum blood flow rate-Resting blood flow rate) / Resting blood flow rate) x 100

  Next, the processing in the blood vessel wall specifying unit 70 in FIG. 1 will be described in detail. The blood vessel wall specifying unit 70 specifies the position of the blood vessel wall in each B-mode image data corresponding to the time phase of the R wave. The blood vessel wall is composed of an inner membrane, a middle membrane, and an outer membrane in order from the inside of the blood vessel. A region inside the blood vessel surrounded by the intima is called a lumen region. In the ultrasonic diagnostic apparatus of FIG. 1, the blood vessel wall specifying unit 70 specifies a lumen region corresponding to the lumen of the blood vessel in the B-mode image data of each time phase, and pixels that go from the lumen region to the outside of the blood vessel. The intima of the blood vessel is specified based on the change in value, and the position of the intima is set as the position of the blood vessel wall.

<Lumen identification processing>
A specific example of the lumen specifying process will be described. In this process, first, pixel value adjustment processing is performed on frame data (B-mode image data of each time phase), and then pixel values are averaged and binarized on frame data. Mask processing is executed. Then, a mask that is one pixel or a set of a plurality of pixels that is a candidate pixel group of the lumen region is detected from each line image, and the top pixel and the bottom pixel of each mask are the mask top pixel and the mask top pixel, respectively. It is detected as a mask lower end pixel. Further, based on the mask upper end pixel and the mask lower end pixel detected from each line image, the contour line on the front wall side of the lumen region and the contour line on the rear wall side of the lumen region are obtained, and these contour lines are Based on this, the lumen region is identified. Hereinafter, each process is demonstrated in order.

"Pixel value adjustment process"
The blood vessel wall specifying unit 70 performs pixel value adjustment processing on the processing target frame data (B-mode image data). This pixel value adjustment process is a process that emphasizes the magnitude of the pixel value. That is, in this process, the pixel value reference value St is specified for the frame data to be processed. Then, the pixel value is changed to a larger value for a pixel having a pixel value larger than the reference value St, and the pixel value is changed to a smaller value for a pixel having a pixel value smaller than the reference value St. Is done. Further, the pixel value is maintained for the pixel having the same pixel value as the reference value St. The reference value St is, for example, a value specified by the user, an intermediate value (median value) between the maximum value and the minimum value of the pixel values in the frame data, or an average value of the pixel values in the frame data. As one processing example, the blood vessel wall specifying unit 70 changes the pixel value D according to the following (Equation 2) for each pixel value D included in the frame data.

(Equation 2) D = tan θ · (D−St) + St
θ is, for example, a value preset in the blood vessel wall specifying unit 70 or a value specified by the user. θ represents the inclination angle of the straight line represented by (Expression 2), and is preferably a value of 45 ° or more. The larger the θ, the greater the degree of enhancement of the pixel value.

"Mask processing"
The blood vessel wall specifying unit 70 performs mask processing on the frame data on which the pixel value adjustment processing has been performed. The mask process is a process of averaging each pixel of the frame data image and further binarizing each averaged pixel.

FIG. 7 conceptually shows a pixel group indicated by one frame data. The frame data image is composed of a plurality of line images arranged in the horizontal direction. This frame data image represents a blood vessel cross section in which the vertical direction coincides with the depth direction of the subject and extends in the horizontal direction. In the frame data, M pixels are arranged in the vertical direction, and N pixels are arranged in the horizontal direction. Further, the vertical direction is assigned the address of _H 1 to H _M, the horizontal direction is assigned the address of _L 1 ~L _N.

The blood vessel wall specifying unit 70 performs mask processing on the pixel at the address (L _i , H _j ) by the following processing. The blood vessel wall specifying unit 70 obtains the average value of the pixel values from the address (L _i , H ₁ ) to the address (L _i , H _M ) as the mask determination value K. Then, the average value of the pixel values from the address (L _i , H _j−p ) to the address (L _i , H _{j + p} ) is obtained as the interval average value ITV _mean (Interval mean). However, when j ≦ p, j ≧ M−p + 1 where the average value of the pixel values from the address (L _i , H ₁ ) to the address (L _i , H _{j + p} ) is the section average value ITV _mean. The average value of the pixel values from the address (L _i , H _jp ) to the address (L _i , H _M ) is set as the section average value ITV _mean . That is, when j ≦ p or j ≧ M−p + 1, since the number of pixels on the front wall side or the rear wall side of the pixel of the address (L _i , H _j ) is less than p, the front wall side or The section average value ITV _mean is obtained as long as the pixels are on the rear wall side.

When the determined section average value ITV _mean exceeds the mask determination value K, the blood vessel wall specifying unit 70 sets 0 as the new pixel value of the address (L _i , H _j ), and determines the calculated section average. When the value ITV _mean is equal to or _smaller than the mask determination value K, 1 is set as a new pixel value of the address (L _i , H _j ).

For example, when the mask processing of p = 5 is performed on the address (L ₃ , H ₇ ), the pixel group from the address (L ₃ , H ₂ ) to the address (L ₃ , H ₁₂ ) shown in FIG. Based on the above, the section average value Av is obtained, and binarization is performed based on the comparison between the section average value ITV _mean and the mask determination value K. Further, to the address _(L 7, _{H 3),} when subjected to the mask processing of p = 5, the pixel groups of the address _{(L 7, H} 1) ~ address _(L 3, _{H 8)} as shown in FIG. 7 The section average value ITV _mean is obtained based on the above, and binarization based on the comparison between the section average value ITV _mean and the mask determination value K is performed.

  FIG. 8 conceptually shows the frame data image subjected to the mask process. In FIG. 8, the shaded pixels are pixels whose pixel values are set to 1, and the pixels that are not shaded are pixels whose pixel values are set to 0. Hereinafter, a pixel having a pixel value of 1 is referred to as an effective pixel. According to such a mask process, a candidate pixel indicating a lumen region is obtained as an effective pixel after the frame data pixels are smoothed.

“Detection of the mask and detection of the top and bottom pixel of the mask”
The blood vessel wall specifying unit 70 obtains upper and lower contour lines of the lumen region of the blood vessel for the frame data subjected to the mask processing, and specifies the lumen region in accordance with the processing described below. Here, a line image indicated by a pixel group whose horizontal address is L _i (i = 1 to N) is represented by a symbol “Li”.

  The blood vessel wall specifying unit 70 detects a mask composed of effective pixels for each of the plurality of line images indicated by the frame data in FIG. The mask is a section that becomes a candidate constituting the lumen region, and is a single pixel or a set of a plurality of pixels. The blood vessel wall specifying unit 70 detects a mask from each of the line images L1 to LN based on the coordinate values of the effective pixels.

  For example, for the frame data shown in FIG. 8, the blood vessel wall specifying unit 70 detects a mask having a length of 12 pixels from the line image L1, and includes a mask having a length of 1 pixel and a 4-pixel length from the line image L2. A mask having a length is detected. Further, a mask having a length of 13 pixels is detected from the line image L3, and a mask having a length of 6 pixels is detected from the line image L4. The blood vessel wall specifying unit 70 similarly detects the mask for each of the line images L5 to LN.

  After detecting the mask, the blood vessel wall specifying unit 70 detects the pixel at the upper end of the mask as the mask upper end pixel and the pixel at the lower end of the mask as the mask lower end pixel for the mask whose mask length is equal to or greater than the predetermined threshold TH. Detect as. Detection of the mask upper end pixel and the mask lower end pixel is performed by acquiring the respective coordinate values. Note that a mask whose mask length is less than the predetermined threshold TH is excluded from detection of the mask upper end pixel and the mask lower end pixel.

  In FIG. 9, the mask upper end pixel and the mask lower end pixel detected when the threshold value TH is 6 pixels long are shown as pixels with a dot “●”. Masks having a pixel length of less than 6 pixels in the line images L2, L7, L8 and L19 are excluded from detection targets of the mask upper end pixel and the mask lower end pixel.

  Here, for convenience of explanation, the threshold value TH is 6 pixels long. However, since the actual pixel is finer than the pixel shown in FIG. 9, the threshold value TH in terms of pixel length is actually larger than this. It becomes. Preferably, the pixel length corresponds to a length shorter than the blood vessel diameter in the subject.

"Identifying contours and lumen regions"
After detecting the mask upper end pixel and the mask lower end pixel, the blood vessel wall specifying unit 70 calculates the contour lines on the front wall side and the rear wall side of the lumen region based on the coordinate values of the mask upper end pixel and the mask lower end pixel. Determine the lumen area. Each contour line of the lumen region is obtained as follows.

  The blood vessel wall specifying unit 70 searches for a mask upper end pixel in a direction crossing the frame data image, and detects a plurality of mask upper end pixels that can be a basis for obtaining a contour line on the front wall side of the lumen region. In this search, the next mask upper end pixel is searched in the right direction of the mask upper end pixel on the condition that the difference in depth is not more than a predetermined value with reference to the position of the mask upper end pixel detected previously. . The blood vessel wall specifying unit 70 obtains a contour on the front wall side based on each position of a plurality of mask upper end pixels detected as pixels that can be a source for obtaining a contour on the front wall side of the lumen region. The blood vessel wall specifying unit 70 obtains the contour line on the rear wall side by the same process as the process for obtaining the contour line on the front wall side. The blood vessel wall specifying unit 70 specifies a region sandwiched between the contour line on the front wall side and the contour line on the rear wall side as a lumen region.

"Specific example of processing to identify lumen area"
A specific example of processing for detecting the mask upper end pixel and the mask lower end pixel, obtaining the contour line of the lumen region, and specifying the lumen region will be described with reference to FIGS. 10 and 11. FIGS. 10 and 11 respectively show a conceptual diagram and a flowchart for explaining the processing for obtaining the contour line on the front wall side of the lumen region.

  In the process shown in the flowchart of FIG. 11, the blood vessel wall specifying unit 70 classifies the mask upper end pixels into a plurality of groups that can be used as a basis for obtaining the contour on the front wall side. Then, the most suitable group for obtaining the contour line on the front wall side is selected, and the contour line on the front wall side is obtained based on the positions of the plurality of mask upper end pixels belonging to the group. Details will be described below with reference to the flowchart of FIG.

The blood vessel wall specifying unit 70 sets the search start line SP extending in the vertical direction on the left side of the line image L1, and sets the search start points SP _{A to} SP _E at intervals δ on the search start line SP (S301). Here, the interval δ is, for example, the minimum value of the inner diameter of the blood vessel to be diagnosed. Further, for convenience of explanation, five search start points, SP _{A to} SP _E , are set, but the number of search start points corresponding to the length of the frame data image in the vertical direction is set. The blood vessel wall specifying unit 70 sets the line image L1 adjacent to the right side of the search start line SP as a search line image for searching for a mask front wall side pixel (S302).

The blood vessel wall specifying unit 70 searches for the mask upper end pixel on the search line image (S303). That is, it is determined whether or not the mask upper end pixel is detected along the search line image (S304). When a mask upper end pixel is detected on the search line image, the mask upper end pixel and the search start point SP _Z , that is, the search start point selected as the processing target among the search start points SP _{A to} SP _E It is determined whether or not the difference in depth d between and is less than or equal to the interval δ (S305).

Vessel wall specifying unit 70, if the difference d is less than spacing δ, the group mask upper pixel of the search line image GRZ, i.e. included in the group corresponding to the search start point SP _Z (S306). Incidentally, in the case where a plurality of such masks upper pixel within the search line image, the depth of the difference between the search start point SP _Z to include the smallest ones group GRZ. The blood vessel wall specifying unit 70 sets the line image L1 that has been set as the search line image as a reference line image to be used as a reference in the processing described later (S307), and sets the line image L2 adjacent to the right side of the line image L1 as a new search line image. (S308).

On the other hand, the vessel wall specifying unit 70 includes a mask upper pixel of the search line image, when the depth of the difference d between the search starting point SP _Z exceeds the spacing δ, the mask upper pixel of the search line image into groups GrZ It does not include and transfers to step S308 (S305).

Vessel wall specifying unit 70, if the mask upper pixel of the search line image is not detected in step S304, or in step S305, the mask upper pixel of the search line image, the depth of the difference between the search start point SP _Z When it is determined that d exceeds the interval δ, the line image L2 adjacent to the right side of the line image L1 that has been the search line image is set as a new search line image (S308).

The blood vessel wall specifying unit 70 searches for a mask upper end pixel on a new search line image (S309), that is, determines whether or not a mask upper end pixel is detected along the search line image (S310). When a mask upper end pixel is detected on the search line image, the mask upper end pixel and the mask upper end pixel of the reference line image (bypassing step S307 and starting the search when moving from step S308 to step S309) It is determined whether or not the depth difference d from the point SP _{Z is} the same hereinafter) is equal to or smaller than the interval δ (S311).

  When the difference d is equal to or smaller than the interval δ, the blood vessel wall specifying unit 70 includes the mask upper end pixel of the search line image in the group GrZ (S312). Note that when there are a plurality of such mask upper end pixels in the search line image, the group GrZ includes the smallest difference in depth from the mask upper end pixel of the reference line image. The blood vessel wall specifying unit 70 determines whether or not the search line image is the rightmost line image LN (S313). If the search line image is a line image LN, the process is terminated. If the search line image is not a line image LN, the line image that has been the search line image is set as a new reference line image (S314). The blood vessel wall specifying unit 70 further sets the line image adjacent to the right side of the line image that has been the search line image as a new search line image (S315), and returns to step S309.

  On the other hand, when the depth difference d between the mask upper end pixel of the search line image and the mask upper end pixel of the reference line image exceeds the interval δ, the blood vessel wall specifying unit 70 groups the mask upper end pixels of the search line image. The process proceeds to step S316 without being included in GrZ (S311).

  When the upper end pixel of the search line image is not detected in step S310, or the depth of the upper end pixel of the search line image and the upper end pixel of the reference line image is determined in step S311. If it is determined that the difference d exceeds the interval δ, it is determined whether or not the search line image is the rightmost line image LN (S316). If the search line image is the line image LN, the process is terminated. If the search line image is not the line image LN, the line image adjacent to the right side of the search line image is set as a new search line image (S315), and the process returns to step S309. .

As an example, a description will be given group GrC corresponding to search starting point SP _C of Figure 10. Mask upper pixel α1 detected line image L1 as search line image, the α7 and alpha 11, not included in the group GrC for depth difference between the search start point SP _C exceeds interval [delta]. Mask upper pixel is detected line image L2 as search line image α8, since the depth of the difference between the search start point SP _C is less than the interval [delta], included in the group GRC. The mask upper end pixel α3 detected using the line image L3 as the search line image is not included in the group GrC because the difference in depth from the mask upper end pixel α8 exceeds the interval δ. Mask upper-end pixels α4 and α13 detected using line image L4 as a search line image are not included in group GrC because the difference in depth from mask upper-end pixel α8 exceeds interval δ. The mask upper end pixel α9 detected using the line image L5 as the search line image is included in the group GrC because the difference in depth from the mask upper end pixel α8 is equal to or smaller than the interval δ. The mask upper end pixel α10 detected using the line image L6 as the search line image is included in the group GrC because the difference in depth from the mask upper end pixel α9 is equal to or smaller than the interval δ. In this way, the mask upper end pixels α7 to α10 are included in the group GrC.

Similarly, including the mask upper pixel α1~α6 group GrA corresponding to the search start point SP _A, include the mask upper pixel α2~α6 group GrB corresponding to the search start point SP _B. Also, including the mask upper pixel α7~α10 group GrD corresponding to the search start point SP _D, including the mask upper pixel α11~α15 group GrE corresponding to the search start point SP _E.

  For each group, the number of times that steps S306 and S307 of FIG. 11 or S311 to S314 are bypassed, that is, the number of line images L1 to LN in which the mask top pixel is not included in the group GrZ is taken as a penalty. Be counted. The penalty indicates the degree to which the group is not suitable for obtaining the contour line. For example, when attention is paid to the line images L1 to L6 shown in FIG. 10, the penalty is 0 for the group GrA because one mask upper end pixel is included in the group GrA from each of the line images L1 to L6. For the group GrB, the penalty is 1 because the mask upper end pixel of the line image L1 is not included in the group GrB. For the group GrC, the penalty is 3 because the mask upper end pixels of the line images L1, L3, and L4 are not included in the group GrC. For the group GrD, the penalty is 2 because the mask upper end pixels of the line images L3 and L4 are not included in the group GrD. For the group GrE, the penalty is 1 because the mask upper end pixel of the line image L3 is not included in the group GrE.

  The blood vessel wall specifying unit 70 extracts a set of mask upper end pixels belonging to the group having the smallest penalty among the groups GrA to GrE. In the example shown in FIG. 10, a set of mask upper end pixels belonging to the group GrA is extracted. The blood vessel wall specifying unit 70 obtains each coordinate value by using a set of pixels obtained by interpolating the extracted set of pixels as a front wall side outline pixel group indicating a front wall side outline of the lumen region. In FIG. 12, the front wall side outline pixel group 44 is indicated by a bold line.

  The blood vessel wall specifying unit 70 performs the same process on the lower mask pixel in each line image, and obtains each coordinate value of the rear wall side contour pixel group indicating the rear wall side contour line of the lumen region. In FIG. 12, the rear wall side outline pixel group 46 is indicated by a bold line.

  The blood vessel wall specifying unit 70 includes a front wall side outline pixel group, a rear wall side outline pixel group, and a front wall side outline pixel group and a rear wall side outline pixel group among pixels included in the frame data image. A pixel group sandwiched between the pixels is specified as a pixel group indicating a lumen region, and coordinate values of each pixel are acquired.

  According to such processing, the front wall side outline pixel group and the rear wall side outline pixel group are specified based on the mask upper end pixel belonging to the group having the smallest penalty. As a result, the coordinate value of the pixel group in the lumen region that is most certain is obtained. Each coordinate value of the pixel group of the lumen area specified in this way is used for an intima specifying process described in detail below.

<Inner membrane specific treatment>
A process executed by the blood vessel wall specifying unit 70 in the intima specifying process will be described. The intima specifying process is performed on the frame data (B-mode image data of each time phase) in which the lumen area of the blood vessel is specified by the above-described lumen specifying process, and an outline representing the outline of the lumen area is obtained. The region from the lumen region to the blood vessel wall is specified, and the luminance in that region, that is, the pixel value is corrected. Thereby, the intima is emphasized, and the intima is specified based on the frame data in which the intima is emphasized. The intima specifying process includes auxiliary processes such as an interpolation process and a filter process for facilitating each process. Hereinafter, each step of the intima specifying process will be described in order.

  The blood vessel wall specifying unit 70 reads frame data to be subjected to intima specifying processing from the data storage unit 50 via the R-wave time phase extracting unit 60. The blood vessel wall specifying unit 70 performs interpolation processing on adjacent pixels in the frame data to increase the number of pixels in the frame data image. Thereby, the resolution of the displayed image can be improved and the visibility can be improved.

  The blood vessel wall specifying unit 70 performs the above-described lumen specifying process on the frame data on which the interpolation processing has been performed, and specifies the lumen region on the frame data image.

  The blood vessel wall specifying unit 70 performs lumen noise filter processing on the frame data in which the lumen region is specified. This process is a process for replacing each pixel value of the lumen region with 0 when the pixel value is equal to or less than a predetermined threshold value. As a result, it is possible to reduce electrical noise generated in each circuit constituting the ultrasonic diagnostic apparatus and noise generated in the blood vessel lumen due to multiple reflections of ultrasonic waves.

  The blood vessel wall specifying unit 70 executes a blood vessel wall inner point setting process based on the frame data on which the lumen noise filter process has been performed. This process is a process of setting a vascular wall inner point for calculation on the vascular wall for each line image indicated by the frame data. The vascular wall inner point is used for calculation in an intima enhancement process described later.

FIG. 13 conceptually shows the distribution of pixel values in one line image. The symbols LE, MB, PC, AvB, and EM in the figure indicate Lumen Estimation, Max of Brightness, Point of Center, AVerage Brightness, and Estimate Media, respectively. The x-axis indicates the position of the ultrasonic wave in the depth direction, and the y-axis indicates the pixel value. Here, the positive direction of the x-axis indicates the direction in which the depth is deep. The point LE _ant indicates the contour on the front wall side of the lumen region specified by the lumen specifying process, and the point LE _post indicates the contour on the rear wall side of the lumen region specified by the lumen specifying process.

The blood vessel wall specifying unit 70 specifies the point MB _ant on the x-axis where the pixel value becomes maximum in the region farther from the blood vessel center than the point LE _ant . Then, the pixel average value AvB _ant in the section from the point LE _ant to the point MB _ant is obtained, and further, the point closest to the blood vessel center among the points on the x-axis where the pixel value becomes the pixel average value AvB _ant is determined in the vascular wall. Set as point EM _ant .

Similarly, the blood vessel wall specifying unit 70 specifies a point MB _post on the x-axis where the pixel value is maximum in a region farther from the blood vessel center than the point LE _post as shown in FIG. Then, the pixel average value AvB _post in the section from the point LE _post to the point MB _post is obtained, and further, the point closest to the blood vessel center among the points on the x-axis where the pixel value becomes the pixel average value AvB _post Set as point EM _post . In general, since the intima is thinner than the media and adventitia, the vascular wall inner points EM _ant and EM _post thus determined are often located in the region from the media to the adventitia.

By such processing, the blood vessel wall specifying unit 70 sets the blood vessel wall inner points EM _ant and EM _post for each line image indicated by the frame data subjected to the lumen region filter processing.

  The blood vessel wall specifying unit 70 performs an averaging filter process on the frame data that has been subjected to the lumen region filter process. In the averaging filter process, an average value is obtained by including the pixel to be processed and pixels around the pixel in the average value calculation population, and the pixel value of the pixel to be processed is set to the obtained average value. To replace. Such an averaging filter process includes, for example, a pixel to be processed and k pixels in the upward direction (all pixels in the upward direction when the number of pixels in the upward direction is less than k), Is included in the population of the average value calculation, and the average value is obtained, and the obtained average value is used as the pixel value of the pixel to be processed, or the pixel to be processed and k pixels in the downward direction (lower When the number of pixels in the direction is less than k, all the pixels in the downward direction) are included in the average value calculation population to obtain an average value, and the obtained average value is the pixel of the pixel to be processed There is processing to be a value. This process is generally referred to as a k-tap moving average filter process.

  In addition, the pixel to be processed and k pixels in the right direction (all pixels in the right direction when the number of pixels in the right direction is less than k) are included in the average value calculation population. The average value is obtained and the obtained average value is used as the pixel value of the pixel to be processed, or the pixel to be processed and k pixels in the left direction (the number of pixels in the left direction is less than k) When all the pixels in the left direction) are included in the average value calculation population, the average value is obtained, and the obtained average value is used as the pixel value of the pixel to be processed. Good.

  Furthermore, the pixel to be processed and the pixels surrounding the pixel are included in the average value calculation population, and the average value (if all of the pixels surrounding the pixel to be processed do not exist, The average value) may be obtained, and the obtained average value may be used as the pixel value of the pixel to be processed.

  By applying an averaging filter process to the frame data, the frame data image is smoothed and the missing portion of the intima can be reduced.

  The blood vessel wall specifying unit 70 performs an intima enhancement process for emphasizing the intima on the frame data that has been subjected to the averaging filter process. In the intima enhancement process, the blood vessel wall specifying unit 70 executes the following process for each line image indicated by the frame data.

The blood vessel wall specifying unit 70 obtains the x coordinate value of the midpoint PC (blood vessel center point) between the blood vessel wall inner points EM _ant and EM _post as the blood vessel center point coordinates xc for the line image to be processed. Furthermore, the x coordinate value of the middle point of the blood vessel center point PC and the blood vessel wall inner point EM _ant is obtained as the anterior wall side blood vessel coordinate xa, and the middle point x coordinate value of the blood vessel center point PC and the blood vessel wall inner point EM _post is obtained. The rear wall side intravascular coordinate xp is obtained. Then, the pixel value D (x) of each pixel included in the line image is corrected and optimized based on the following (Equation 3) to (Equation 5).

(Expression 3) D (x) = D (x) + G · W (x)
Here, G is a predetermined constant, for example, the pixel average value in the line image to be processed. When x ≧ xc,
(Expression 4) W (x) = γ · (x−xp)
When x <xc,
(Expression 5) W (x) = − γ · (x−xa)

  γ is a normalization constant, for example, 1 / (xp−xa). By determining γ in this manner, −0.5 or more in each of the range of x where xc−2 (xc−xa) ≦ x ≦ xc and the range of xc ≦ x ≦ xc + 2 (xp−xc) The value of W (x) is normalized within a range of 0.5 or less. (Expression 3) means that the pixel value D (x) is corrected by adding a correction value G · W (x) depending on the x coordinate value. W (x) shown in (Equation 4) and (Equation 5) is a function whose value increases as it approaches the intima from the blood vessel center point. That is, since the constant G is a constant value, the value of the function W (x) increases as the blood vessel center point approaches the intima, and the intima is emphasized. More specifically, in the region on the anterior wall side from the blood vessel center point, an increasing function having a value of 0 at the anterior wall side intravascular coordinate point (x = xa) is defined as W (x). In the rear wall side region, W (x) is a decreasing function whose value is 0 at the rear wall side intravascular coordinate point (x = xp).

  As shown in (Equation 4) and (Equation 5), W (x) is linearly defined by a linear function, and W (x) is curvedly defined by a quadratic function, an exponential function, or the like. May be. Also in this case, −0.5 or more and 0.5 or less in each of the range x of xc−2 (xc−xa) ≦ x ≦ xc and the range of xc ≦ x ≦ xc + 2 (xp−xc) The value of W (x) may be normalized in the range.

  By such processing, the blood vessel wall specifying unit 70 performs processing for emphasizing the intima by applying (Equation 3) to (Equation 5) for each line image indicated by the frame data subjected to the smoothing filter processing. Run.

  The blood vessel wall specifying unit 70 executes processing for obtaining an intima line based on the frame data on which intima enhancement processing has been performed. This process is performed by searching for an intima point for each line image. FIG. 14 shows a distribution of pixel values in one line image as a conceptual diagram for explaining processing for searching for an intimal point. The IP code in the figure indicates Intima Point.

Vessel wall specifying unit 70 calculates the x-coordinate value of the nearest point of inflection point _{LE ant} in the region of the side away from the vessel center than the point _{LE ant} as coordinate values _{xI ant} of the front wall side in the membrane point _{IP ant.} This coordinate value xI _ant is the x coordinate value of the point at which the absolute value of the inclination first takes the maximum value when the absolute value of the inclination is sequentially obtained from the point LE _ant toward the negative direction of the x axis. .

Similarly, blood vessel wall identifying unit 70, on the side of the area away from the vessel centerline than the point _{LE post,} the coordinate values of the rear wall side in the film point _{IP post} the x-coordinate value of the nearest point of inflection point _{LE post} xI _Calculate as _post . This coordinate value xI _post is the x coordinate value of the point at which the absolute value of the inclination first takes the maximum value when the absolute value of the inclination is sequentially obtained from the point LE _{post in} the positive direction of the x-axis. .

Vessel wall identification unit 70, by such process, determining the coordinates _{xI post} coordinates _{xI ant} and the rear wall side in the film point _{IP post} of the front wall side in the membrane point _{IP ant} for each line image indicated by the frame data . The blood vessel wall specifying unit 70 interpolates the front wall side intima point IP _ant obtained for each line image, and displays an intimal line indicating the cross-sectional shape of the intima on the front wall side (each pixel group representing an intimal line) Find the coordinate value. Further, the rear wall side intima point IP _post obtained for each line image is interpolated to obtain an intima line (each coordinate value of a pixel group representing the intima line) indicating the intima on the rear wall side.

  In this way, each coordinate value of the pixel group representing the intimal line on the front wall side and the rear wall side specified in the blood vessel wall specifying unit 70 in FIG. 1 is set as the position of the blood vessel wall, and the display image forming unit 80 in FIG. Used in Then, the display image forming unit 80 forms the display image shown in FIG. 6, for example, and the display image is displayed on the display unit 90 in FIG.

  As mentioned above, although preferred embodiment of this invention was described, embodiment mentioned above is only a mere illustration in all the points, and does not limit the scope of the present invention. The present invention includes various modifications without departing from the essence thereof.

  DESCRIPTION OF SYMBOLS 10 Probe, 12 Transmission / reception part, 20 B mode image formation part, 30 Memory image selection part, 40 Operation device, 50 Data storage part, 60 R wave time phase extraction part, 70 Blood vessel wall specific part, 80 Display image formation part, 90 Display section.

Claims (7)

A probe for transmitting and receiving ultrasound,
A transmission / reception unit that obtains a reception signal from a diagnostic region including a blood vessel in a living body by controlling transmission of the probe;
An image data forming unit that forms image data of a diagnostic region for each time phase based on a reception signal obtained over a plurality of time phases within a diagnosis period;
A data storage unit that stores image data of a plurality of time phases within a period of interest selected within a diagnosis period and biological signal data obtained by measuring pulsations in the living body in association with each other;
A specific time phase extraction unit that extracts image data of a specific time phase within a pulsation cycle based on biological signal data from image data of a plurality of time phases within the attention period;
A blood vessel wall specifying unit for specifying the position of the blood vessel wall in the image data of a specific time phase;
A display image forming unit for forming a display image of the blood vessel diameter obtained based on the position of the blood vessel wall;
Having
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 1,
The display image forming unit forms a display image including an A mode waveform corresponding to a line specified in the image data of a specific time phase.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 1 or 2,
The display image forming unit forms a display image including an M mode image in which line images obtained from lines designated in image data of a specific time phase are arranged over a plurality of time phases.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 3.
The display image forming unit displays a marker indicating the position of the blood vessel wall specified in the blood vessel wall specifying unit in the M-mode image;
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 3 or 4,
The display image forming unit forms a display image including a change waveform of the blood vessel diameter along the time axis direction of the M-mode image with respect to the blood vessel diameter calculated based on the position of the blood vessel wall. And the time axis of the M mode image are aligned and displayed.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to any one of claims 3 to 5,
The display image forming unit displays a display image including a blood flow rate or blood flow change waveform along a time axis direction of the M-mode image with respect to a blood flow rate or blood flow obtained based on Doppler information in a blood vessel. Forming and displaying the time axis of the blood flow velocity or blood flow change waveform and the time axis of the M-mode image,
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to any one of claims 1 to 6,
The blood vessel wall specifying unit specifies a lumen region corresponding to the lumen of the blood vessel in the image data, specifies a vascular intima based on a change in pixel value from the lumen region toward the outside of the blood vessel, The position of the intima is the position of the blood vessel wall,
An ultrasonic diagnostic apparatus.

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