Ultrasonic diagnostic device, control method for ultrasonic diagnostic device, and processor for ultrasonic diagnostic device

Abstract

To provide an ultrasonic diagnostic device capable of performing measurement easily while improving measurement accuracy of a blood flow rate.SOLUTION: An ultrasonic diagnostic device includes: a first blood vessel wall detection unit for detecting a blood vessel wall in a short axis direction from a B mode image; a first blood vessel diameter calculation unit for calculating a first blood vessel diameter in the short axis direction; a second blood vessel wall detection unit for detecting a blood vessel wall in a longitudinal axis direction from the B mode image; a second blood vessel diameter calculation unit for calculating a second blood vessel diameter in the longitudinal direction; a blood flow velocity calculation unit for calculating a blood flow velocity on the basis of Doppler data in a Doppler gate on the B mode image; and a blood flow rate measuring unit for measuring a blood flow rate on the basis of the blood vessel wall and the blood flow velocity in the longitudinal axis direction or in the short axis direction. When the calculated second blood vessel diameter is maintained within a range prescribed with respect to the calculated first blood vessel diameter over a prescribed number of frames, transition is made to the measurement of the blood flow rate automatically.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an ultrasonic diagnostic apparatus for acquiring B-mode data and Doppler data, a control method for an ultrasonic diagnostic apparatus, and a processor for an ultrasonic diagnostic apparatus. [Background technology]

[0002] Ultrasound diagnostic devices have been known for obtaining images of the inside of a subject. Ultrasound diagnostic devices generally include an ultrasound probe equipped with a transducer array in which a plurality of elements are arranged. With the ultrasound probe in contact with the body surface of the subject, ultrasound beams are transmitted from the transducer array toward the inside of the subject, and ultrasound echoes from the subject are received by the transducer array to obtain element data. Furthermore, the ultrasound diagnostic device electrically processes the obtained element data to generate an ultrasound image of the corresponding part of the subject.

[0003] For example, Patent Document 1 discloses an ultrasound diagnostic device that measures the blood flow rate in a specified vascular region when a user specifies a vascular region on an ultrasound image displayed on a display device, while the display device displays an ultrasound image including a long-axis view of the subject's blood vessels. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2019-187649 Summary of the Invention [Problem to be solved by the invention]

[0005] In order to measure blood flow accurately, it is desirable that the long-axis image of the blood vessel included in the ultrasound image corresponds to the longitudinal cross section of the blood vessel passing through the center of the blood vessel, i.e., the longitudinal cross section of the blood vessel where the measured blood vessel diameter is maximum. However, in Patent Document 1, the position of the ultrasound probe is determined based on the user's judgment based on experience, etc., and then the ultrasound image including the long-axis image of the blood vessel is acquired, so there are cases where an ultrasound image including an appropriate long-axis image of the blood vessel cannot be obtained. Furthermore, in the invention of Patent Document 1, the user needs to specify the blood vessel region to measure blood flow, so there is room for improvement in simplifying the measurement.

[0006] The present invention has been made to solve these conventional problems, and has as its object to provide an ultrasonic diagnostic apparatus that can easily measure blood flow while improving the measurement accuracy. [Means for solving the problem]

[0007] In order to achieve the above object, the ultrasonic diagnostic apparatus according to the present invention includes a transducer array that acquires received signals by transmitting and receiving ultrasonic waves to and from a subject, a B-mode processing unit that generates a B-mode image in which at least blood vessels are imaged based on the received signals, a display unit that displays the B-mode image generated by the B-mode processing unit, a first vascular wall detection unit that detects vascular walls in the short-axis direction by analyzing the B-mode image in which a short-axis image of the blood vessel is imaged, a first vascular diameter calculation unit that calculates a first vascular diameter based on the vascular walls in the short-axis direction detected by the first vascular wall detection unit, a second vascular wall detection unit that detects vascular walls in the long-axis direction by analyzing the B-mode image in which a long-axis image of the blood vessel is imaged, and a display unit that calculates a first vascular diameter based on the vascular walls in the long-axis direction detected by the second vascular wall detection unit. a gate setting unit that sets a Doppler gate within the blood vessel on a B-mode image in which a long-axis image is captured; a Doppler processing unit that acquires Doppler data within the Doppler gate; a blood flow velocity calculation unit that calculates the blood flow velocity based on the Doppler data; and a blood flow measurement unit that measures the blood flow rate based on the detected blood vessel wall in the long-axis direction or the blood vessel wall in the short-axis direction and the calculated blood flow velocity, wherein the second blood vessel diameter calculation unit determines whether the second blood vessel diameter has a value within a predetermined range relative to the first blood vessel diameter, and automatically proceeds to measuring the blood flow rate when the calculated second blood vessel diameter remains within the predetermined range relative to the calculated first blood vessel diameter over a predetermined number of frames.

[0008] The second vascular wall detection unit sets a search line on the B-mode image to search for the vascular wall in the longitudinal direction, and can detect the anterior and posterior vascular walls as the vascular wall in the longitudinal direction based on the brightness profile of the B-mode image on the set search line. In this case, the second vascular wall detection unit can set detection point markers on the detected anterior and posterior vascular walls and display them on the display device. The gate setting unit can also set a Doppler gate having a center position and size determined based on the coordinates of the anterior and posterior walls of the blood vessel detected by the second blood vessel wall detection unit.

[0009] In addition, the second vascular wall detection unit can estimate the vascular running angle based on at least one of the detected anterior and posterior vascular walls, and set the Doppler steer angle so that the angle correction value for the vascular running angle is within 60 degrees. In this case, the B-mode processing unit can generate a B-mode image based on the B-mode steering angle set in accordance with the blood vessel running angle estimated by the second blood vessel wall detection unit.

[0010] In addition, the Doppler processing unit generates a Doppler waveform image based on the Doppler data, and the display device can display both the B-mode image generated by the B-mode processing unit and the Doppler waveform image generated by the Doppler processing unit. Furthermore, the Doppler processing unit generates a Doppler waveform image in parallel with the generation of a B-mode image by the B-mode processing unit, and both the B-mode image and the Doppler waveform image are frozen and the blood flow measurement unit measures the blood flow. Alternatively, after the B-mode image is frozen, the Doppler processing unit acquires Doppler data within the Doppler gate to generate a Doppler waveform image, and the Doppler waveform image is frozen and the blood flow measurement unit measures the blood flow.

[0011] The control method for an ultrasound diagnostic apparatus according to the present invention comprises the steps of: generating a B-mode image in which at least a blood vessel is imaged based on a received signal obtained by transmitting and receiving ultrasound to and from a subject; displaying the B-mode image; detecting a vascular wall in the short-axis direction by analyzing a short-axis image of the blood vessel imaged in the B-mode image; calculating a first vascular diameter based on the detected vascular wall in the short-axis direction; detecting a vascular wall in the long-axis direction by analyzing a B-mode image in which a long-axis image of the blood vessel is imaged; calculating a second vascular diameter based on the detected vascular wall in the long-axis direction; setting a Doppler gate within the blood vessel on the B-mode image in which a long-axis image is imaged when the calculated second vascular diameter remains within a predetermined range for the calculated first vascular diameter over a predetermined number of frames; acquiring Doppler data within the Doppler gate; calculating a blood flow velocity based on the Doppler data; and measuring a blood flow volume based on the detected vascular wall in the long-axis direction or the short-axis direction and the calculated blood flow velocity.

[0012] The processor for an ultrasound diagnostic device according to the present invention generates a B-mode image in which at least a blood vessel is imaged based on a received signal obtained by transmitting and receiving ultrasound to and from a subject, displays the B-mode image, detects a vascular wall in the short axis direction by analyzing a short-axis image of the blood vessel imaged in the B-mode image, calculates a first vascular diameter based on the detected vascular wall in the short axis direction, detects a vascular wall in the long axis direction by analyzing a B-mode image in which a long-axis image of the blood vessel is imaged, calculates a second vascular diameter based on the detected vascular wall in the long axis direction, sets a Doppler gate within the blood vessel on the B-mode image in which a long-axis image is imaged when the calculated second vascular diameter remains within a predetermined range for the calculated first vascular diameter over a predetermined number of frames, acquires Doppler data within the Doppler gate, calculates a blood flow velocity based on the Doppler data, and measures a blood flow volume based on the detected vascular wall in the long axis direction or the short-axis direction and the calculated blood flow velocity. [Effects of the Invention]

[0013] According to the present invention, there is provided a first vascular wall detection unit that detects vascular walls in the short axis direction by analyzing B-mode images in which short-axis images of blood vessels are captured, a first vascular diameter calculation unit that calculates a first vascular diameter based on the vascular walls in the short axis direction, a second vascular wall detection unit that detects vascular walls in the long axis direction by analyzing B-mode images in which long-axis images of blood vessels are captured, a second vascular diameter calculation unit that calculates a second vascular diameter based on the vascular walls in the long axis direction, a gate setting unit that sets a Doppler gate within the blood vessel on a B-mode image in which long-axis images are captured, a Doppler processing unit that acquires Doppler data within the Doppler gate, a blood flow velocity calculation unit that calculates blood velocity based on the Doppler data, and a blood flow measurement unit that measures blood flow based on either the vascular walls in the long axis direction or the vascular walls in the short axis direction and the blood flow velocity. When the calculated second vascular diameter remains within a specified range for the calculated first vascular diameter over a specified number of frames, the system automatically switches to blood flow measurement, thereby enabling easy measurement while improving the measurement accuracy of blood flow. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a block diagram showing the configuration of an ultrasound diagnostic apparatus according to a first embodiment of the present invention. [Figure 2] 1 is a block diagram showing an internal configuration of a receiving circuit according to a first embodiment of the present invention. [Figure 3] FIG. 2 is a block diagram showing the internal configuration of a B-mode processing unit according to the first embodiment of the present invention. [Figure 4] FIG. 2 is a diagram schematically illustrating an example of a B-mode image showing a short-axis view of a blood vessel. [Figure 5] FIG. 10 is a diagram schematically illustrating an example of a brightness profile of an image on a straight line that crosses a short-axis image of a blood vessel. [Figure 6] FIG. 2 is a diagram schematically illustrating an example of a B-mode image showing a long-axis view of a blood vessel. [Figure 7] FIG. 10 is a diagram schematically illustrating an example of a brightness profile of an image on a straight line that crosses a long-axis image of a blood vessel. [Figure 8] FIG. 10 is a diagram schematically showing the estimated running angle of a blood vessel on a B-mode image. [Figure 9] FIG. 3 is a diagram schematically showing a method for setting a B-mode steering angle in the first embodiment of the present invention. [Figure 10] FIG. 2 is a diagram schematically showing a method for setting a Doppler steer angle in the first embodiment of the present invention. [Figure 11] 10 is a graph showing the relationship between the angle between an ultrasound beam and blood flow and the estimation error of blood flow velocity. [Figure 12] 2 is a diagram schematically showing a B-mode image displayed on a display device and a Doppler gate set on the B-mode image in the first embodiment of the present invention. FIG. [Figure 13] FIG. 2 is a block diagram showing the internal configuration of a Doppler processing unit in the first embodiment of the present invention. [Figure 14] 4 is a flowchart showing the operation of the ultrasound diagnostic apparatus according to the first embodiment of the present invention. [Figure 15] 2A and 2B are diagrams showing a schematic view of a B-mode image and a Doppler waveform image displayed on a display device in the first embodiment of the present invention. [Figure 16] 4 is a flowchart showing the operation of automatic blood flow measurement in the first embodiment of the present invention. [Figure 17] FIG. 2 is a diagram schematically showing a B-mode image, a Doppler waveform image, and a blood flow measurement value displayed on a display device in the first embodiment of the present invention. [Figure 18] FIG. 10 is a diagram schematically showing measurement point markers arranged on a short-axis image of a blood vessel. [Figure 19] FIG. 10 is a diagram schematically showing measurement point markers arranged on a long-axis image of a blood vessel. [Figure 20] 10 is a flowchart showing the operation of the ultrasound diagnostic apparatus according to the second embodiment of the present invention. [Figure 21] FIG. 10 is a block diagram schematically showing the change in blood vessel diameter over time in the second embodiment of the present invention. [Figure 22] FIG. 10 is a block diagram showing the configuration of an ultrasound diagnostic apparatus according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. The following description of the components will be given based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In this specification, a numerical range expressed using "to" means a range that includes the numerical values before and after "to" as the lower and upper limits. In this specification, the terms "perpendicular" and "parallel" include the range of tolerance permitted in the technical field to which the present invention pertains. For example, "perpendicular" and "parallel" mean a deviation of less than ±10 degrees from strict perpendicular or parallel, and the deviation from strict perpendicular or parallel is preferably 5 degrees or less, and more preferably 3 degrees or less. In this specification, "identical" and "the same" include a generally accepted margin of error in the technical field. Furthermore, in this specification, when "all," "any," or "entirely" is used, it includes not only the case of 100%, but also the generally accepted margin of error in the technical field, such as 99% or more, 95% or more, or 90% or more.

[0016] Embodiment 1 Fig. 1 shows the configuration of an ultrasound diagnostic apparatus 1 according to a first embodiment of the present invention. As shown in Fig. 1, the ultrasound diagnostic apparatus 1 includes a transducer array 2, to which a transmission circuit 3 and a reception circuit 4 are connected, respectively. The transmission circuit 3 and reception circuit 4 form a transmission / reception circuit 5. A B-mode (Brightness mode) processing unit 6 and a Doppler processing unit 7 are connected to the reception circuit 4, and a display device 9 is connected to the B-mode processing unit 6 and the Doppler processing unit 7 via a display control unit 8.

[0017] A first vascular wall detection unit 10 is connected to the B-mode processing unit 6, and a first vascular diameter calculation unit 11 is connected to the first vascular wall detection unit 10. A second vascular wall detection unit 12 is connected to the B-mode processing unit 6, and a second vascular diameter calculation unit 13 and a gate setting unit 14 are connected to the second vascular wall detection unit 12. The gate setting unit 14 is connected to the Doppler processing unit 7. A blood flow velocity calculation unit 15 is connected to the Doppler processing unit 7. A blood flow rate measurement unit 16 is connected to the first vascular diameter calculation unit 11, the second vascular diameter calculation unit 13, and the blood flow velocity calculation unit 15. The first vascular wall detection unit 10, the first vascular diameter calculation unit 11, the second vascular wall detection unit 12, the second vascular diameter calculation unit 13, the gate setting unit 14, and the blood flow rate measurement unit 16 are connected to the display control unit 8.

[0018] An apparatus control unit 17 is connected to the transmission / reception circuit 5, B-mode processing unit 6, Doppler processing unit 7, display control unit 8, first vascular wall detection unit 10, first vascular diameter calculation unit 11, second vascular wall detection unit 12, second vascular diameter calculation unit 13, gate setting unit 14, blood flow velocity calculation unit 15, and blood flow measurement unit 16. An input device 18 and a storage unit 19 are also connected to the apparatus control unit 17. The apparatus control unit 17 and the storage unit 19 are connected to each other so that information can be exchanged in both directions. The transducer array 2 is included in an ultrasound probe 21. A processor 22 for the ultrasound diagnostic device 1 is configured by the B-mode processing unit 6, the Doppler processing unit 7, the display control unit 8, the first vascular wall detection unit 10, the first vascular diameter calculation unit 11, the second vascular wall detection unit 12, the second vascular diameter calculation unit 13, the gate setting unit 14, the blood flow velocity calculation unit 15, and the blood flow measurement unit 16.

[0019] The transducer array 2 of the ultrasonic probe 21 shown in Fig. 1 has a plurality of transducers arranged one-dimensionally or two-dimensionally. Each of these transducers transmits ultrasonic waves in accordance with a drive signal supplied from a transmission circuit 3, receives ultrasonic echoes from the subject, and outputs a signal based on the ultrasonic echoes. Each transducer is configured by forming electrodes on both ends of a piezoelectric element made of, for example, a piezoelectric ceramic typified by PZT (Lead Zirconate Titanate), a polymer piezoelectric element typified by PVDF (Poly Vinylidene Di Fluoride), or a piezoelectric single crystal typified by PMN-PT (Lead Magnesium Niobate-Lead Titanate).

[0020] The transmission circuit 3 includes, for example, a plurality of pulse generators, and adjusts the delay amount of each drive signal and supplies it to the plurality of transducers in the transducer array 2 so that the ultrasound waves transmitted from the plurality of transducers form an ultrasound beam based on a transmission delay pattern selected in response to a control signal from the device control unit 17. In this way, when a pulsed or continuous wave voltage is applied to the electrodes of the transducers in the transducer array 2, the piezoelectric material expands and contracts, and pulsed or continuous wave ultrasound is generated from each transducer, and an ultrasound beam is formed from the composite wave of these ultrasound waves.

[0021] The transmitted ultrasonic beam is reflected by an object, such as a part of the subject, and propagates toward the transducer array 2 of the ultrasonic probe 21. The ultrasonic waves propagating toward the transducer array 2 in this manner are received by each transducer constituting the transducer array 2. At this time, each transducer constituting the transducer array 2 expands and contracts upon receiving the propagating ultrasonic echo, generating electrical signals, which are then output to the receiving circuit 4.

[0022] The receiving circuit 4 processes the signal output from the transducer array 2 in accordance with a control signal from the device control unit 17 to generate received data, which is so-called RF (Radio Frequency) data. As shown in Fig. 2, the receiving circuit 4 has a configuration in which an amplifier 23, an AD (Analog Digital) converter 24, and a beam former 25 are connected in series.

[0023] The amplifier 23 amplifies signals input from each transducer constituting the transducer array 2 and transmits the amplified signals to the AD converter 24. The AD converter 24 converts the signals transmitted from the amplifier 23 into digital data and transmits these data to the beamformer 25. The beamformer 25 performs so-called reception focusing processing by adding each piece of data converted by the AD converter 24 with a respective delay in accordance with the speed of sound or a distribution of speed of sound set based on the reception delay pattern selected in response to a control signal from the device control unit 17. This reception focusing processing performs phasing and addition of each piece of data converted by the AD converter 24, and acquires reception data in which the focus of the ultrasonic echo is narrowed.

[0024] As shown in FIG. 3, the B-mode processing unit 6 has a configuration in which a signal processing unit 26, a DSC (Digital Scan Converter) 27, and an image processing unit 28 are connected in series. The signal processing unit 26 performs correction for attenuation due to distance in accordance with the depth of the ultrasonic wave reflection position on the reception data generated by the reception circuit 4, and then performs envelope detection processing to generate a B-mode image signal, which is tomographic image information regarding the tissue within the subject. The DSC 27 converts (raster converts) the B-mode image signal generated by the signal processing unit 26 into an image signal that conforms to the scanning method of a normal television signal. The image processing unit 28 performs various necessary image processing such as gradation processing on the B-mode image signal input from the DSC 27, and then outputs the B-mode image signal to the display control unit 8. Hereinafter, the B-mode image signal that has been subjected to image processing by the image processing unit 28 will be simply referred to as a B-mode image.

[0025] When the B-mode image generated by the B-mode processing unit 6 includes a short-axis image of the subject's blood vessels, the first vascular wall detection unit 10 detects the vascular wall in the short-axis direction by analyzing the short-axis image of the blood vessels captured in the B-mode image. Here, the short-axis image of the blood vessel refers to a cross section of the blood vessel along a direction perpendicular to the running direction of the blood vessel.

[0026] When detecting a vascular wall in the short axis direction, the first vascular wall detection unit 10 sets a search region R1 of the blood vessel B in the center of the azimuth direction perpendicular to the depth direction D1 of the B-mode image UB, i.e., the horizontal direction D2, as shown in Fig. 4, and detects the brightness on a virtual search line SL1 extending along the depth direction D1 of the B-mode image UB while scanning the virtual search line SL1 in the horizontal direction D2 within the set search region R1 to create a brightness profile of the image along the search line SL1 in the search region R1. The brightness profile of the image represents the relationship between the depth in the B-mode image UB and the brightness of the image on the search line SL1, as shown in Fig. 5, for example. In the example shown in Fig. 5, depth is plotted on the horizontal axis and brightness is plotted on the vertical axis. 4 shows, as examples of the search line SL1, a dotted search line SL1 that passes through a location on the short-axis image of the blood vessel B relatively far from the center of the blood vessel B, and a solid search line SL1 that passes near the center of the blood vessel B. Also, FIG. 5 shows, as examples of the brightness profile, a dotted line graph G1 corresponding to the dotted search line SL1 and a solid line graph G2 corresponding to the solid search line SL1.

[0027] Here, the change in image brightness on the search line SL1 passing through the short-axis image of the blood vessel B is greater at two points X1 and X2 corresponding to the blood vessel wall than at other points on the search line SL1. Therefore, for example, in the brightness profile of FIG. 5, the two depths J1 and J2 where the brightness value becomes a local maximum value greater than a certain brightness threshold K1 correspond to the two points X1 and X2 corresponding to the blood vessel wall. Furthermore, when the search line SL1 is scanned in the horizontal direction D2 on the short-axis image of the approximately circular blood vessel B, the value of the difference L1 between the depths J1 and J2 in the brightness profile increases from zero to a maximum value corresponding to the diameter of the blood vessel B and then decreases to zero as the search line SL1 is scanned from one end of the short-axis image of the blood vessel B to the other end in the horizontal direction D2. Thus, the value of the difference L1 calculated while the search line SL1 is scanned in the horizontal direction D2 on the short-axis image of the blood vessel B changes to have a local maximum value.

[0028] Therefore, the first vascular wall detection unit 10 can determine whether a short-axis image of a blood vessel is included in the B-mode image UB based on the brightness profile created while scanning the search line SL1 in the horizontal direction D2. For example, the first vascular wall detection unit 10 calculates the difference L1 between depths J1 and J2 in the brightness profile while scanning the search line SL1 in the horizontal direction D2. If the calculated difference L1 changes to have a local maximum value, the first vascular wall detection unit 10 can recognize that a short-axis image of a blood vessel B is present within the search region R1 of the B-mode image UB. In this case, the first vascular wall detection unit 10 detects, as a blood vessel wall, the locus of points X1 and X2 corresponding to depths J1 and J2 where the brightness value becomes a local maximum in the brightness profile. Furthermore, the first vascular wall detection unit 10 detects information on the positions of points X1M and X2M corresponding to depths J1M and J2M where the calculated difference L1 becomes a maximum value L1M while scanning the search line SL1 in the horizontal direction D2, and sends this information to the first vascular diameter calculation unit 11. Points X1M and X2M correspond to the intersections of the search line SL1 passing through the center of the blood vessel B and the contour line of the short-axis image of the blood vessel B.

[0029] The first blood vessel diameter calculation unit 11 calculates a first blood vessel diameter corresponding to the diameter of the blood vessel B based on the information on the positions of points X1M and X2M on the blood vessel wall received from the first blood vessel wall detection unit 10. The first blood vessel diameter calculation unit 11 can display the calculated first blood vessel diameter DF on the display device 9, for example, as shown in FIG.

[0030] The second vascular wall detection unit 12 detects the vascular wall in the long axis direction by analyzing the B-mode image UB, which is generated based on the first vascular diameter DF calculated by the first vascular diameter calculation unit 11 and which captures a long axis image of the blood vessel B. Here, the long axis image of the blood vessel B refers to a longitudinal cross section of the blood vessel B along the running direction of the blood vessel B.

[0031] When detecting a vascular wall in the longitudinal direction, the second vascular wall detection unit 12 sets a search area R2 in the center of the B-mode image UB in the horizontal direction D2, as shown in Figure 6, and in the set search area R2, detects the brightness on a virtual search line SL2 extending along the depth direction D1 while scanning the virtual search line SL2 in the horizontal direction D2, and creates a brightness profile of the image along the search line SL2, as shown in Figure 7. 6 shows, as examples of the search line SL2, a dotted search line SL2 and a solid search line SL2 positioned at a different position from the search line SL2. Also, in FIG. 7, as examples of brightness profile graphs, a dotted graph G3 corresponding to the dotted search line SL2 and a solid graph G4 corresponding to the solid search line SL2 are shown. Graphs G3 and G4 are shifted from each other in a direction parallel to the horizontal axis, but the difference in depth between the two points at which the brightness is maximized is almost the same.

[0032] Here, the change in brightness of the image along the search line SL2 passing through the long-axis image of the blood vessel B is larger at two points X3 and X4 corresponding to the vascular wall than at other points on the search line SL2, similar to the change in brightness of the image along the search line SL1 passing through the short-axis image of the blood vessel B. Therefore, for example, in the brightness profile of FIG. 7, the two depths J3 and J4 where the brightness value becomes a maximum value greater than a certain brightness threshold K2 correspond to the two points X3 and X4 corresponding to the vascular wall. Also, as shown in FIG. 6, when the search line SL2 is scanned in the horizontal direction D2 on the long-axis image of the tubular blood vessel B extending generally along the horizontal direction D2, the difference L2 between the depths J3 and J4 in the brightness profile ideally hardly changes even when the search line SL2 is scanned in the horizontal direction D2, and even if it does change, the range of the change is small.

[0033] Therefore, the second vascular wall detection unit 12 can determine whether or not the B-mode image UB contains a long-axis image of the blood vessel B based on the brightness profile created while scanning the search line SL2 in the horizontal direction D2. For example, the second vascular wall detection unit 12 calculates the difference L2 between depth J3 and depth J4 in the brightness profile while scanning the search line SL2 in the horizontal direction D2, and can determine that the long-axis image of the blood vessel B is present within the search region R2 of the B-mode image UB if the value of the calculated difference L2 is approximately constant. Here, the value of the difference L2 being approximately constant means, for example, that the difference between the maximum and minimum values of the difference L2 is equal to or less than a certain value.

[0034] The second vascular wall detection unit 12 detects the position of the relatively shallow depth J3 of the depths J3 and J4 where the brightness value reaches a maximum as the position of the vascular anterior wall W1 and detects the position of the relatively deep depth J4 as the position of the vascular posterior wall W2. The second vascular wall detection unit 12 also transmits information on the detected positions of the vascular anterior wall W1 and vascular posterior wall W2 to the second vascular diameter calculation unit 13.

[0035] The second vascular diameter calculation unit 13 calculates the second vascular diameter of the blood vessel B based on information about the positions of the blood vessel anterior wall W1 and the blood vessel posterior wall W2 detected by the second vascular wall detection unit 12. For example, the second vascular diameter calculation unit 13 calculates the longest distance between the blood vessel anterior wall W1 and the blood vessel posterior wall W2 in the depth direction D1 as the second vascular diameter. The second vascular wall detection unit 12 displays the calculated second vascular diameter DS on the display device 9, as shown in FIG.

[0036] Furthermore, second blood vessel diameter calculation unit 13 compares the calculated second blood vessel diameter DS with the first blood vessel diameter DF calculated by first blood vessel diameter calculation unit 11 to determine whether the second blood vessel diameter DS has a value within a predetermined range that includes the first blood vessel diameter DF. If second blood vessel diameter calculation unit 13 determines that the second blood vessel diameter DS has a value within the predetermined range, it determines that a B-mode image UB including a long-axis image of blood vessel B representing a longitudinal cross section passing through the center of blood vessel B has been obtained, and sends a value of the second blood vessel diameter DS within the predetermined range to blood flow measurement unit 16.

[0037] The second vascular wall detection unit 12 also estimates the blood vessel running angle in the B-mode image UB. The second vascular wall detection unit 12 can estimate the gradient of the blood vessel B, for example, by estimating a line passing through multiple positions on the detected blood vessel anterior wall W1 and a line passing through multiple positions on the detected blood vessel posterior wall W2, and averaging the gradients of the two estimated lines. In the example shown in FIG. 6, a virtual blood vessel gradient line BL representing the gradient of the blood vessel B is obtained. The second vascular wall detection unit 12 may also estimate the gradient of the blood vessel B based on either the line passing through multiple positions on the detected blood vessel anterior wall W1 or the line passing through multiple positions on the detected blood vessel posterior wall W2.

[0038] In addition, the second vascular wall detection unit 12 can estimate the angle between the obtained vascular gradient line BL and a virtual straight line AL along the depth direction D1 of the B-mode image UB as the vascular running angle BA, for example, as shown in Figure 8. Further, the second blood vessel wall detection unit 12 sets the B-mode steer angle using the estimated blood vessel running angle BA. For example, as shown in FIG. 9, angles A1 and the like are set as the B-mode steer angle. The B-mode steer angle is defined as the angle between the scanning line when the B-mode image UB is generated by the B-mode processing unit 6 and the straight line AL along the depth direction D1 in the B-mode image UB. Here, the second blood vessel wall detection unit 12 sets the B-mode steer angle so that the angle between the scanning line when the B-mode image UB is generated and the blood vessel gradient line BL approaches 90 degrees in order to obtain a B-mode image UB in which the blood vessel front wall W1 and the blood vessel rear wall W2 are clearly imaged.

[0039] For example, when the second blood vessel wall detection unit 12 uses the blood vessel running angle BA, the defined angle A1, and the defined angle A2 larger than the angle A1, and the relationship of 90 - BA < A1 / 2 is satisfied, the B-mode steer angle is set to 0 degrees; when the relationship of A1 / 2 ≤ 90 - BA < A2 / 2 is satisfied, the B-mode steer angle is set to the angle A1 as shown in FIG. 9; and when the relationship of A2 / 2 ≤ 90 - BA is satisfied, the B-mode steer angle can be set to the angle A2. Here, for example, the angle A1 can be preset to 7.5 degrees and the angle A2 can be preset to 15 degrees.

[0040] In addition, the second blood vessel wall detection unit 12 sets the Doppler steer angle using the estimated blood vessel running angle BA. For example, as shown in FIG. 10, angles B1 or B2 and the like are set as the Doppler steer angle. Here, the Doppler steer angle refers to the inclination angle of the scanning line when Doppler data is acquired.

[0041] Here, it is known that there is a relationship shown in Fig. 11 between the angle H between the ultrasonic beam transmitted into blood vessel B to acquire Doppler data and the blood flow in blood vessel B, and the estimation error E of the blood flow velocity calculated based on the acquired Doppler data. According to this relationship, it can be seen that the larger the angle H of the ultrasonic beam relative to the blood flow, the larger the estimation error E of the blood flow velocity exponentially. It can also be seen that the larger the error in angle correction relative to the blood vessel running angle, the larger the estimation error E of the blood flow velocity.

[0042] Furthermore, it is known that, regarding the angle H between the ultrasound beam and the blood flow and the estimation error E of the blood flow velocity, if the angle H between the ultrasound beam and the blood flow is kept within 60 degrees, for example, even if there is an error of 3 degrees in the angle correction of the blood vessel running angle, the estimation error E of the blood flow velocity will be within 10%, and the blood flow velocity can be calculated with high accuracy. Therefore, in order to calculate the blood flow velocity with high accuracy, the second vascular wall detection unit 12 sets the Doppler steer angle so that the angle correction value for the blood vessel running angle BA, i.e., the angle between the scanning line and the blood vessel gradient line BL, is within 60 degrees.

[0043] For example, the second vascular wall detection unit 12 can set the Doppler tear angle to 0 degrees when the relationship BA<60 is satisfied, the Doppler tear angle to angle B1 when the relationship 60≦BA<60+B1 is satisfied, and the Doppler tear angle to angle B2 when the relationship 60+B1≦BA is satisfied, using a blood vessel running angle BA, a defined angle B1, and an angle B2 larger than angle B1 as shown in Fig. 10. Here, for example, angle B1 can be preset to 15 degrees, and angle B2 can be preset to 30 degrees.

[0044] 12, the gate setting unit 14 sets a Doppler gate DG in the vascular region BR on the B-mode image UB, the Doppler gate DG having a center position and size determined based on the coordinates of the vascular anterior wall W1 and the coordinates of the vascular posterior wall W2 detected by the second vascular wall detection unit 12. In this case, the gate setting unit 14 can set, for example, a midpoint C between the positions of two points X3 and X4 detected by the second vascular wall detection unit 12 as the positions of the vascular anterior wall W1 and the vascular posterior wall W2 as the center position of the Doppler gate DG, and set the Doppler gate DG on a virtual straight line JL that passes through the midpoint C and is inclined by the set Doppler tear angle with respect to the depth direction D1.

[0045] The straight line JL corresponds to a scanning line. The gate setting unit 14 can set the length calculated by multiplying the second vascular diameter DS calculated by the second vascular wall detection unit 12 by a predetermined value as the gate width LG of the Doppler gate DG. Here, the predetermined value by which the second vascular diameter DS is multiplied is a number greater than 0 and equal to or less than 1.00, such as 0.75, and is determined, for example, by a user's input operation via the input device 18. Furthermore, the gate setting unit 14 displays the set Doppler gate DG on the display device 9, superimposed on the B-mode image UB, as shown in FIG.

[0046] The Doppler processing unit 7 acquires Doppler data within a Doppler gate DG set in the vascular region BR by the gate setting unit 14, and generates a Doppler waveform image based on the acquired Doppler data. As shown in Fig. 13, the Doppler processing unit 7 has a configuration in which a quadrature detection unit 29, a high-pass filter 30, a fast Fourier transformer 31, and a Doppler waveform image generation unit 32 are connected in series, and a data memory 33 is connected to the output terminal of the quadrature detection unit 29.

[0047] The quadrature detection unit 29 performs quadrature detection on the received data generated by the receiving circuit 4 by mixing a carrier signal of a reference frequency with the received data, thereby converting the received data into complex data. The high-pass filter 30 functions as a so-called wall filter, and removes frequency components resulting from the movement of the subject's internal tissue from the complex data generated by the quadrature detection unit 29 .

[0048] The fast Fourier transform unit 31 performs frequency analysis by Fourier transforming the complex data of the plurality of sample points to determine the blood flow velocity and generate a spectrum signal. Doppler waveform image generating unit 32 generates a Doppler waveform image signal by aligning the spectral signals generated by fast Fourier transform unit 31 on the time axis and representing the magnitude of each frequency component as brightness. Hereinafter, the Doppler waveform image signal generated by Doppler waveform image generating unit 32 will be simply referred to as a Doppler waveform image. Furthermore, the data memory 33 stores the complex data converted from the received data by the quadrature detector 29 .

[0049] The blood flow velocity calculation unit 15 calculates the blood flow velocity by the so-called pulse Doppler method based on the Doppler data acquired by the Doppler processing unit 7. The blood flow velocity calculation unit 15 can also calculate the average blood flow velocity in each cardiac period. The blood flow measurement unit 16 calculates the cross-sectional area of the blood vessel B based on the second blood vessel diameter DS corresponding to the diameter of the blood vessel B, calculated by the second blood vessel diameter calculation unit 13, assuming that the blood vessel has a circular cross-sectional area. Furthermore, the blood flow measurement unit 16 measures the blood flow rate, which indicates the volume of blood flowing in the blood vessel B per unit time, based on the calculated cross-sectional area of the blood vessel B and the blood flow velocity calculated by the blood flow velocity calculation unit 15.

[0050] The device control unit 17 controls each unit of the ultrasound diagnostic device 1 based on a program stored in advance in the storage unit 19 or the like and an input operation by the user via the input device 18 . Under the control of the device control unit 17, the display control unit 8 performs predetermined processing on the B-mode image UB generated by the B-mode processing unit 6, the Doppler waveform image generated by the Doppler processing unit 7, etc., and displays the B-mode image UB, the Doppler waveform image, etc. on the display device 9.

[0051] The display device 9 displays a B-mode image UB, a Doppler waveform image, etc. under the control of the display control unit 8, and includes display devices such as an LCD (Liquid Crystal Display) and an organic EL display (Organic Electroluminescence Display). The input device 18 is used by the user to perform input operations, and can be configured to include a keyboard, a mouse, a trackball, a touchpad, a touch panel, and the like.

[0052] The storage unit 19 stores the operating program of the ultrasound diagnostic apparatus 1, and may be a storage medium such as a flash memory, an HDD (Hard Disc Drive), an SSD (Solid State Drive), an FD (Flexible Disc), an MO disk (Magneto-Optical disc), an MT (Magnetic Tape), a RAM (Random Access Memory), a CD (Compact Disc), a DVD (Digital Versatile Disc), an SD card (Secure Digital card), or a USB memory (Universal Serial Bus memory), or a server.

[0053] The processor 22 having the B-mode processing unit 6, Doppler processing unit 7, display control unit 8, first vascular wall detection unit 10, first vascular diameter calculation unit 11, second vascular wall detection unit 12, second vascular diameter calculation unit 13, gate setting unit 14, blood flow velocity calculation unit 15, blood flow measurement unit 16 and device control unit 17 is composed of a CPU (Central Processing Unit) and a control program for causing the CPU to perform various processes, but may also be composed using an FPGA (Field Programmable Gate Array), DSP (Digital Signal Processor), ASIC (Application Specific Integrated Circuit), GPU (Graphics Processing Unit), or other ICs (Integrated Circuits), or may be composed of a combination of these.

[0054] In addition, the B-mode processing unit 6, Doppler processing unit 7, display control unit 8, first vascular wall detection unit 10, first vascular diameter calculation unit 11, second vascular wall detection unit 12, second vascular diameter calculation unit 13, gate setting unit 14, blood flow velocity calculation unit 15, blood flow measurement unit 16 and device control unit 17 of the processor 22 can also be partially or entirely integrated into a single CPU or the like.

[0055] The operation of the ultrasound diagnostic device 1 according to the first embodiment will be described in detail below using the flowchart shown in FIG. First, in step S1, a B-mode image UB is generated with the ultrasound probe 21 in contact with the body surface of the subject so that a short-axis image of the subject's blood vessel B is captured by the user, and the generated B-mode image UB is displayed on the display device 9. When the B-mode image UB is generated, ultrasonic beams are transmitted from multiple transducers of the transducer array 2 in accordance with drive signals from the transmission circuitry 3, and received signals are output from each transducer that receives an ultrasonic echo from the subject to the reception circuitry 4, amplified by the amplifier 23, AD converted by the AD converter 24, and then phased and added by the beamformer 25 to generate received data. In the B-mode processing unit 6, this received data is subjected to envelope detection processing by the signal processor 26 to become a B-mode image signal, which is output to the display controller 8 via the DSC 27 and the image processor 28, and the B-mode image UB is displayed on the display device 9 under the control of the display controller 8.

[0056] In step S2, the first vascular wall detection unit 10 sets a search region R1 in the B-mode image UB generated in step S1 and determines whether or not a short-axis image of the blood vessel B is present within the set search region R1. In this case, the first vascular wall detection unit 10, for example, as shown in Fig. 4, detects the brightness of the image on a virtual search line SL1 extending along a depth direction D1 in the search region R1 while scanning the virtual search line SL1 in a lateral direction D2, and creates a brightness profile as shown in Fig. 5.

[0057] The first vascular wall detection unit 10 calculates the difference L1 between two depths J1 and J2 where the brightness value reaches a maximum value greater than a certain brightness threshold K1 in a brightness profile created while scanning the search line SL1 in the horizontal direction D2. For example, when the value of the difference L1 calculated while scanning the search line SL1 from one end to the other end of the search region R1 in the horizontal direction D2 changes to reach a maximum value, the first vascular wall detection unit 10 determines that a short-axis image of the blood vessel B is present within the search region R1. Furthermore, when the value of the difference L1 does not change to reach a maximum value but remains approximately constant, the first vascular wall detection unit 10 determines that a short-axis image of the blood vessel B is not present within the search region R1.

[0058] In step S2, if it is determined that the short-axis image of blood vessel B does not exist within the search region R1, the process returns to step S1, and a B-mode image UB is generated while the user adjusts the position and orientation of the ultrasound probe 21. If it is determined in step S2 that a short-axis image of blood vessel B exists within search region R1, first vascular wall detection unit 10 detects, as a vascular wall, the locus of points X1 and X2 corresponding to depths J1 and J2 where the brightness value is maximized in the brightness profile. Furthermore, first vascular wall detection unit 10 sends to first vascular diameter calculation unit 11 information on the positions of points X1M and X2M corresponding to depths J1M and J2M where difference L1 calculated while scanning search line SL1 in lateral direction D2 is maximized to L1M.

[0059] In step S3, the first blood vessel diameter calculation unit 11 calculates a first blood vessel diameter DF corresponding to the diameter of the blood vessel B by measuring the distance between points X1M and X2M on the blood vessel wall corresponding to depths J1M and J2M where the difference L1 is maximum, as detected in step S2. The first blood vessel diameter calculation unit 11 displays the calculated first blood vessel diameter DF on the display device 9, as shown in FIG. In the following step S4, the user changes the orientation of the ultrasound probe 21 to capture a long-axis image of the blood vessel B, and a B-mode image UB is generated.

[0060] In step S5, the second vascular wall detection unit 12 determines whether a long-axis image of the blood vessel B is present in the B-mode image UB generated in step S4. At this time, the second vascular wall detection unit 12 sets a search region R2 on the B-mode image UB, as shown in Fig. 6, for example, and detects the brightness on a virtual search line SL2 extending along the depth direction D1 while scanning the search line SL2 in the lateral direction D2 within the set search region R2. As a result, the second vascular wall detection unit 12 creates a brightness profile as shown in Fig. 7.

[0061] The second vascular wall detection unit 12 calculates the difference L2 between two depths J3 and J4 where the brightness value is a maximum value greater than a certain brightness threshold K2 in the brightness profile created while scanning the search line SL2 in the horizontal direction D2, and determines that a long axis image of blood vessel B is present within the search region R2 of the B-mode image UB if the value of the calculated difference L2 is approximately constant, and determines that a long axis image of blood vessel B is not present within the search region R2 if the value of the difference L2 is not approximately constant.

[0062] If it is determined in step S5 that the long axis image of blood vessel B is not present in the B-mode image UB, the process returns to step S4, where the user adjusts the position and orientation of the ultrasound probe 21, and a new B-mode image UB is generated. In step S5, if it is determined that a long-axis image of blood vessel B is present in the B-mode image UB, the second vascular wall detection unit 12 detects the positions of depths J3 and J4 where the brightness value becomes maximum in the long-axis image of the recognized blood vessel B as the position of the anterior wall W1 of the blood vessel and the position of the posterior wall W2 of the blood vessel, respectively.

[0063] In step S6, the second blood vessel diameter calculation unit 13 calculates a second blood vessel diameter DS corresponding to the diameter of the blood vessel B based on the long-axis image of the blood vessel B detected in step S5. For example, the second blood vessel diameter calculation unit 13 calculates the longest distance in the depth direction D1 between the anterior wall W1 and the posterior wall W2 of the blood vessel as the second blood vessel diameter DS. As shown in FIG. 6, the second blood vessel diameter calculation unit 13 displays the calculated second blood vessel diameter DS on the display device 9.

[0064] In step S7, the second blood vessel diameter calculation unit 13 compares the calculated second blood vessel diameter DS with the first blood vessel diameter DF calculated in step S3 to determine whether the second blood vessel diameter DS has a value within a predetermined range that includes the first blood vessel diameter DF. The predetermined range is set, for example, as a range having a lower limit that is a certain value lower than the first blood vessel diameter DF and an upper limit that is a certain value higher than the first blood vessel diameter DF.

[0065] If it is determined in step S7 that the second vascular diameter DS is outside the predetermined range, the process returns to step S4, and the processes of steps S4 to S7 are performed again. At this time, the user adjusts the position of the ultrasound probe 21 while checking the value of the second vascular diameter DS displayed on the display device 9 so that the value of the second vascular diameter DS approaches the value of the first vascular diameter DF. If it is determined in step S7 that the second vascular diameter DS is within the specified range, it is determined that a B-mode image UB including a long-axis image of blood vessel B having the first vascular diameter DF, i.e., a long-axis image of blood vessel B representing a longitudinal cross section passing through the center of blood vessel B, has been obtained, and the process proceeds to step S8.

[0066] In step S8, the second vascular wall detection unit 12 estimates the gradient of the blood vessel B using the B-mode image UB obtained in step S7, which includes a long-axis image of the blood vessel B having the second blood vessel diameter DS within the predetermined range, and estimates the blood vessel running angle BA from the estimated gradient of the blood vessel B. For example, the second vascular wall detection unit 12 estimates a line passing through multiple positions on the blood vessel anterior wall W1 and a line passing through multiple positions on the blood vessel posterior wall W2 detected in step S5, and estimates the gradient of the blood vessel B by averaging the slopes of the two estimated lines, thereby obtaining a virtual blood vessel gradient line BL representing the gradient of the blood vessel B, as shown in FIG. 8. The second vascular wall detection unit 12 can estimate the angle between the obtained blood vessel gradient line BL and a virtual line AL along the depth direction D1 of the B-mode image UB as the blood vessel running angle BA.

[0067] In the subsequent step S9, the second blood vessel wall detection unit 12 sets a B-mode steer angle representing the inclination angle of the scanning line when the B-mode image UB is generated by the B-mode processing unit 6, using the blood vessel running angle BA estimated in step S8. At this time, for example, the second blood vessel wall detection unit 12 uses the blood vessel running angle BA, the defined angle A1 shown in FIG. 9, and the defined angle A2 larger than the angle A1, and when the relationship of 90 - BA < A1 / 2 is satisfied, sets the B-mode steer angle to 0 degrees, when the relationship of A1 / 2 ≤ 90 - BA < A2 / 2 is satisfied, sets the B-mode steer angle to the angle A1, and when the relationship of A2 / 2 ≤ 90 - BA is satisfied, can set the B-mode steer angle to the angle A2. Here, for example, the angle A1 can be preset to 7.5 degrees and the angle A2 can be preset to 15 degrees.

[0068] In step S10, the second blood vessel wall detection unit 12 sets a Doppler steer angle representing the inclination angle of the scanning line when Doppler data is acquired by the Doppler processing unit 7, using the blood vessel running angle BA estimated in step S8. At this time, for example, the second blood vessel wall detection unit 12 uses the blood vessel running angle BA, the defined angle B1 as shown in FIG. 10, and the angle B2 larger than the angle B1, and when the relationship of BA < 60 is satisfied, sets the Doppler steer angle to 0 degrees, when the relationship of 60 ≤ BA < 60 + B1 is satisfied, sets the Doppler steer angle to the angle B1, and when the relationship of 60 + B1 ≤ BA is satisfied, can set the Doppler steer angle to the angle B2. Here, for example, the angle B1 can be preset to 15 degrees and the angle B2 can be preset to 30 degrees.

[0069] In step S11, the gate setting unit 14 sets a Doppler gate DG, whose center position and size are determined based on the coordinates of the vascular anterior wall W1 and the vascular posterior wall W2 detected in step S5, within the vascular region BR on the B-mode image UB used to estimate the vascular course angle BA in step S8, as shown in Fig. 12. In this case, the gate setting unit 14 may, for example, set the midpoint C between the positions of two points X3 and X4 detected in step S5 as the positions of the vascular anterior wall W1 and the vascular posterior wall W2 as the center position of the Doppler gate DG, and set the length calculated by multiplying the second vascular diameter DS measured in step S6 by a predetermined value as the gate width LG of the Doppler gate DG. Here, the predetermined value by which the second vascular diameter DS is multiplied is a number greater than 0 and equal to or less than 1.00, such as 0.75, and may be determined, for example, by a user's input operation via the input device 18. Furthermore, the gate setting unit 14 displays the set Doppler gate DG on the display device 9, superimposed on the B-mode image UB, as shown in FIG.

[0070] In step S12, the Doppler processing unit 7 starts continuously generating Doppler waveform images and displays the generated Doppler waveform images on the display device 9. At this time, the Doppler processing unit 7 acquires Doppler data in the Doppler gate DG set in step S10 as shown in FIG. 12, continuously generates Doppler waveform images based on the acquired Doppler data, and displays the generated Doppler waveform images on the display device 9. The B-mode processing unit 6 also starts continuously generating B-mode images UB and displays the generated B-mode images UB on the display device 9. As a result, both the B-mode images UB and Doppler waveform images are continuously generated, and the B-mode images UB and Doppler waveform images UD are displayed on the display device 9 as shown in FIG.

[0071] In step S13, the Doppler waveform WD in the Doppler waveform image UD generated in step S11 is adjusted so that the Doppler processing unit 7 can acquire Doppler data with high accuracy. Generally, the Doppler waveform WD changes periodically in accordance with the heartbeat, as shown in FIG. 15 . Therefore, the Doppler waveform WD is adjusted, for example, from the point at which the start and end positions of the cardiac cycle are detected. The adjustment of the Doppler waveform WD also includes adjusting the horizontal axis, i.e., the baseline position, of the graph of the Doppler waveform WD and adjusting the scale of the vertical axis of the Doppler waveform WD. The adjustment of the Doppler waveform WD not only adjusts the display of the Doppler waveform WD on the display device 9, but also controls the transmission circuit 3 via the device control unit 17 to adjust the repetition frequency of the ultrasonic pulses transmitted into the subject from the transducer array 2 of the ultrasound probe 21. In this way, the Doppler waveform WD is adjusted so that, for example, the maximum and minimum values of the Doppler waveform WD fall within 70% of the scale of the vertical axis.

[0072] Generally, the blood flow velocity in a blood vessel increases during systole and decreases during diastole, so that, as shown in Fig. 15, the amount of change in the Doppler waveform WD is large during systole P1 and small during diastole P2. Therefore, in step S14, period information of the Doppler waveform WD is acquired, and based on the acquired period information, it is determined whether the current time point is in diastole P2 of the subject's heart. If it is determined that the current time point is not in diastole P2 of the subject's heart, the process returns to step S13. If it is determined that the current time point is in diastole P2 of the subject's heart, the process proceeds to step S15.

[0073] In step S15, both the B-mode image UB and the Doppler waveform image UD displayed on the display device 9 are frozen. Here, "freezing and displaying the B-mode image UB and the Doppler waveform image UD" means that, in a state in which the B-mode images UB continuously generated by the B-mode processing unit 6 and the Doppler waveform images UD continuously generated by the Doppler processing unit 7 are displayed on the display device 9, the display of the B-mode image UB and the Doppler waveform image UD is temporarily stopped, and one still B-mode image UB and one still Doppler waveform image UD are displayed on the display device 9. In this way, the Doppler data in the diastolic phase P2, where the amount of change in the Doppler waveform WD is small, can be used to measure the blood flow rate.

[0074] In the following step S16, the blood flow rate in the vascular region BR is automatically measured. This step S16 will be explained using the flowchart shown in Fig. 16. Step S16 is made up of steps S18 to S20. First, in step S18, the blood flow measurement unit 16 assumes that the blood vessel B has a circular cross section and calculates the cross-sectional area of the blood vessel B based on the second blood vessel diameter DS determined to be within the range defined in step S7.

[0075] Next, in step S19, the blood flow velocity calculation unit 15 calculates the blood flow velocity based on the Doppler data acquired by the Doppler processing unit 7 when the B-mode image UB and the Doppler waveform image UD are frozen and displayed in step S15. At this time, the blood flow velocity calculation unit 15 can also calculate the average blood flow velocity during the cardiac cycle period. In the following step S20, the blood flow measurement unit 16 calculates the blood flow rate, which represents the volume of blood flowing within blood vessel B per unit time, based on the cross-sectional area of blood vessel B calculated in step S18 and the blood flow velocity calculated in step S19. In this way, the automatic measurement of blood flow volume in step S16 is completed.

[0076] In step S17, the blood flow measurement result obtained in step S16 is displayed on the display device 9. For example, as shown in Fig. 17, the blood flow measurement value MV is displayed on the display device 9 together with the B-mode image UB and the Doppler waveform image UD. In this way, when the measured value MV of the blood flow volume is displayed on the display device 9, the operation of the ultrasonic diagnostic apparatus 1 ends.

[0077] As described above, according to the ultrasound diagnostic apparatus 1 of the first embodiment of the present invention, the first blood vessel diameter DF is calculated based on the B-mode image UB representing a short-axis image of the blood vessel B, the B-mode image UB representing a long-axis image passing through the center of the blood vessel B is accurately acquired based on the first blood vessel diameter DF, and the blood flow rate is measured using the acquired B-mode image UB representing the long-axis image of the blood vessel B. Therefore, it is possible to reduce fluctuations in the measurement accuracy of the blood flow rate caused by the user adjusting the position of the ultrasound probe 21 on the body surface of the subject, and improve the measurement accuracy.

[0078] Furthermore, by acquiring a B-mode image UB representing a long axis image passing through the center of blood vessel B, blood flow measurement is performed automatically and the blood flow measurement results are displayed on the display device 9, making it easy to measure blood flow. In particular, although not shown, even when the user has both hands full, such as when the display device 9 is configured as a small portable display and the user holds the display device 9 in one hand and the ultrasound probe 21 in the other, the ultrasound diagnostic device 1 according to the first embodiment of the present invention does not require the user to perform any operation via the input device 18 or the like, and therefore blood flow can be easily measured.

[0079] In step S2, the first vascular wall detection unit 10 sets a search region R1 on the B-mode image UB and searches for a short-axis image of the blood vessel B within the set search region R1, but it is also possible to search for the short-axis image of the blood vessel B throughout the entire B-mode image UB. However, considering the need to reduce the amount of calculation required for the process of searching for the blood vessel B and to quickly recognize the short-axis image of the blood vessel B, it is preferable to search for the short-axis image of the blood vessel B within the search region R1. Similarly, in step S5, the long axis image of blood vessel B can be searched for throughout the entire B-mode image UB, but from the viewpoint of quickly recognizing the long axis image of blood vessel B, it is preferable to search for the long axis image of blood vessel B within search region R2.

[0080] Furthermore, when capturing a short-axis image of blood vessel B, the position of the short-axis image of blood vessel B in the lateral direction D2 is likely to change on multiple consecutively generated frames of B-mode images UB due to small changes in the tilt and position of the ultrasound probe 21 in contact with the body surface of the subject. Therefore, the first vascular wall detection unit 10 tracks and recognizes the short-axis image of blood vessel B, for example, by detecting movement of the short-axis image of blood vessel B between consecutive frames of B-mode images UB. To detect movement of the short-axis image of blood vessel B, for example, a method of scanning a search line SL1 over the entire B-mode image UB and comparing the obtained brightness profile with the brightness profile for the previously detected short-axis image of blood vessel B, or a general image analysis method such as so-called pattern matching, can be used. In this way, by tracking the short-axis image of blood vessel B, the first vascular diameter DF of the short-axis image of blood vessel B can be easily calculated even if the short-axis image of blood vessel B moves between consecutive frames.

[0081] 18, when a short-axis image of blood vessel B is recognized in step S2, measurement point markers M1 and M2 may be displayed on the display device 9 at the positions of two intersections between a search line SL1 passing through the center of blood vessel B and the contour line of blood vessel B, that is, at the positions of depths J1 and J2 where the difference L1 in the depth direction D1 between the depths J1 and J2 measured in step S2 is maximum. By displaying the measurement point markers M1 and M2 in this way, the user can understand that a short-axis image of blood vessel B has been recognized in step S2 and the measurement positions of the blood vessel diameter.

[0082] Similarly, when a long axis image of blood vessel B is recognized in step S5, measurement point markers M3 and M4 can be displayed on the display device 9 at the intersection of the search line SL2 and the anterior wall W1 of the blood vessel and the intersection of the search line SL2 and the posterior wall W2 of the blood vessel, as shown in Figure 19.

[0083] Furthermore, when a short-axis image of blood vessel B is recognized, instead of displaying measurement point markers M1 and M2, it is also possible to change the display mode, such as the color and thickness of the outline of the recognized short-axis image of blood vessel B. Similarly, when a long-axis image of blood vessel B is recognized, instead of displaying measurement point markers M3 and M4, it is also possible to change the display mode, such as the color and thickness of the outline of the recognized long-axis image of blood vessel B.

[0084] In addition, in steps S2 and S5, the brightness profiles of the images along the search lines SL1 and SL2 are used to recognize the short-axis image and long-axis image of the blood vessel B, but the method for recognizing the short-axis image and long-axis image of the blood vessel B is not limited to this. For example, a so-called template matching method may be used, in which typical pattern data of the short-axis image and long-axis image of the blood vessel B is stored in advance as a template, the similarity to the pattern data is calculated while searching the B-mode image UB with the template, and the short-axis image or long-axis image of the blood vessel B is deemed to be present at the location where the similarity is greater than or equal to a threshold and is at its maximum.

[0085] In addition to simple template matching, similarity calculations can also use, for example, the machine learning method described in Csurka et al.: Visual Categorization with Bags of Keypoints, Proc. of ECCV Workshop on Statistical Learning in Computer Vision, pp. 59-74 (2004), or the general image recognition method using deep learning described in Krizhevsk et al.: ImageNet Classification with Deep Convolutional Neural Networks, Advances in Neural Information Processing Systems 25, pp. 1106-1114 (2012).

[0086] In step S3, the first vascular diameter DF is calculated based on information about the vascular wall detected in step S2 for one frame of B-mode image UB. However, the first vascular diameter DF may be calculated based on information about the vascular wall detected for multiple frames of B-mode image UB. For example, if the values of the first vascular diameter DF calculated over a predetermined number of frames, such as 5 to 10 frames, are equal to or less than a certain value, the first vascular diameter calculation unit 11 may calculate the maximum first vascular diameter DF among the first vascular diameters DF calculated for the predetermined number of B-mode images UB as the final value of the first vascular diameter DF. Alternatively, for example, the first vascular diameter calculation unit 11 may calculate the average value of the first vascular diameters DF calculated for the predetermined number of B-mode images UB as the final value of the first vascular diameter DF.

[0087] This makes it possible to eliminate cases where the calculated first vascular diameter DF has abnormal values, such as values that are very large or very small compared to the actual diameter of blood vessel B, and therefore makes it possible to calculate the final value of the first vascular diameter DF with high accuracy.

[0088] Furthermore, the determination in step S7 can be made based on the second vascular diameter DS calculated for multiple frames of B-mode images UB. For example, if the second vascular diameter DS calculated over a predetermined number of frames, such as 5 to 10 frames, remains within a predetermined range, such as 5 to 10 frames, that includes the first vascular diameter DF calculated in step S3, the second vascular diameter calculator 13 determines that the second vascular diameter DS has a value within the predetermined range, and the process can proceed to step S8. This improves the accuracy of the determination in step S7, enabling the B-mode image UB representing a longitudinal cross section passing through the center of the blood vessel B to be acquired with high accuracy.

[0089] Furthermore, the second vascular diameter calculation unit 13 can calculate the maximum second vascular diameter DS among the second vascular diameters DS calculated for the B-mode images UB of the specified number of frames used when it was determined that the second vascular diameter DS has a value within the specified range as the final value of the second vascular diameter DS. At this time, the second vascular wall detection unit 12 can perform the processes of steps S8 to S11 using, for example, the B-mode images UB used to calculate the final second vascular diameter DS.

[0090] Furthermore, the second vascular diameter calculation unit 13 can average the second vascular diameters DS calculated for the B-mode images UB of the predetermined number of frames used when it was determined that the second vascular diameter DS has a value within the predetermined range, and calculate the calculated average value as the final value of the second vascular diameter DS. At this time, the second vascular wall detection unit 12 can perform the processes of steps S8 to S11 using, for example, the B-mode image UB acquired last among the B-mode images UB of the predetermined number of frames.

[0091] Furthermore, the value of the first vascular diameter DF calculated in step S3 can also be displayed together with the long-axis image of blood vessel B and the value of the second vascular diameter DS displayed on display device 9 in steps S5 to S7. In this case, the user can adjust the position of ultrasound probe 21 while checking the value of the first vascular diameter DF so that the second vascular diameter DS calculated in step S6 approaches the first vascular diameter DF. This allows the user to adjust the position of ultrasound probe 21 more easily.

[0092] Furthermore, when the first blood vessel diameter DF is calculated in step S3, the first blood vessel diameter calculation unit 11 can calculate the distance between the short-axis image of blood vessel B and the body surface of the subject as the first blood vessel depth based on, for example, the relatively shallow depth J1 of the depths J1 and J2 corresponding to the positions of the blood vessel wall detected in step S2, and display the calculated first blood vessel depth on the display device 9.

[0093] Furthermore, when the second vascular diameter DS is calculated in step S6, the second vascular diameter calculation unit 13 can calculate the distance between the vascular anterior wall W1 and the subject's body surface as the second vascular depth based on the depth J3 corresponding to the position of the vascular anterior wall W1 detected in step S5, and display the calculated second vascular depth on the display device 9.

[0094] Here, in steps S4 to S7, both the calculated first blood vessel depth and second blood vessel depth can be displayed on the display device 9. This allows the user to compare the first blood vessel depth with the second blood vessel depth and check whether the long-axis image of blood vessel B in the B-mode image UB generated in step S4 corresponds to the short-axis image of blood vessel B in the B-mode image UB generated in step S1, while adjusting the position of the ultrasound probe 21. This prevents the long-axis image of blood vessel B that does not correspond to the short-axis image of blood vessel B in the B-mode image UB generated in step S1 from being captured in step S4, and allows the appropriate long-axis image of blood vessel B to be captured, thereby improving the measurement accuracy of the blood flow rate.

[0095] Furthermore, for example, the first blood vessel depth may be taken into consideration when the long-axis image of blood vessel B is recognized in step S5. For example, if the fluctuation range of the difference L2 between depths J3 and J4 calculated by the second blood vessel wall detection unit 12 while scanning the search line SL2 in the horizontal direction D2 is equal to or less than the fluctuation range threshold, and in addition, the second blood vessel depth has a value within a depth range including the first blood vessel depth, it is determined that the long-axis image of blood vessel B is present within the search region R2. If the fluctuation range of the difference L2 calculated while scanning the search line SL2 in the horizontal direction D2 is greater than the fluctuation range threshold, or if the second blood vessel depth has a value outside the depth range, it is determined that the long-axis image of blood vessel B is not present within the search region R2. This also makes it possible to prevent a long-axis image of the blood vessel B that does not correspond to the short-axis image of the blood vessel B in the B-mode image UB generated in step S1 from being captured in step S4.

[0096] Alternatively, by providing a step between steps S11 and S12 in which B-mode images UB including long-axis images of blood vessel B are successively generated and a step in which the position of the long-axis image of blood vessel B is determined to have stabilized, the process can proceed to step S11 when the position of the long-axis image of blood vessel B has stabilized. For example, when the change in the position of the long-axis image of blood vessel B in multiple frames of B-mode images UB generated within a predetermined time period, such as one second, is equal to or less than a predetermined value, such as 0.2 mm, the position of the long-axis image of blood vessel B is determined to be stable. When the change in the position of the long-axis image of blood vessel B in multiple frames of B-mode images UB generated within a predetermined time period, such as one second, is greater than a predetermined value, such as 0.2 mm, the position of the long-axis image of blood vessel B is determined to be unstable.

[0097] In this way, the processing from step S11 onward is triggered by the stabilization of the position of the long axis image of blood vessel B in the B-mode image UB, i.e., the stabilization of the position of the ultrasound probe 21 placed on the body surface of the subject. Therefore, the blood flow rate can be measured using a stable image, and the measurement accuracy of the blood flow rate can be improved.

[0098] Furthermore, although the processes of steps S5 to S7 are performed on the B-mode image UB generated in step S4, the processes of steps S5 to S7 can also be performed on the B-mode image UB generated in any of steps S12 to S14. In this case, for example, instead of the second vascular diameter DS determined to be within the range determined in step S7, the cross-sectional area of the blood vessel B can be calculated in step S18 using the second vascular diameter DS calculated for the B-mode image UB generated in any of steps S12 to S14 and determined to be within a predetermined range including the first vascular diameter DF calculated in step S3.

[0099] Furthermore, in step S18, the cross-sectional area of blood vessel B may be calculated based on the first blood vessel diameter DF calculated in step S3, instead of the blood flow measurement unit 16 calculating the cross-sectional area of blood vessel B based on the second blood vessel diameter DS determined to be within the predetermined range. For example, when the first blood vessel diameter DF is larger than the second blood vessel diameter DS determined to be within the predetermined range, the cross-sectional area of blood vessel B is calculated based on the first blood vessel diameter DF.

[0100] Furthermore, although a Doppler waveform image UD is generated in step S12 and displayed on display device 9, the Doppler waveform image UD does not necessarily have to be displayed on display device 9 as long as Doppler waveform WD data is acquired. In this way, even when the Doppler waveform image UD is not displayed on display device 9, the blood flow rate is measured in step S16 based on the Doppler waveform WD data acquired in step S13 and the value of the second vascular diameter DS determined to be within the range determined in step S7, just as when the Doppler waveform image UD is displayed on display device 9. Furthermore, when the Doppler waveform image UD is not displayed on display device 9, acquisition of the Doppler waveform WD data may simply be stopped instead of freeze-displaying the Doppler waveform image UD on display device 9 in step S15.

[0101] In addition, in step S13, an example is shown in which adjustment of the Doppler waveform WD is performed from the time when the start and end positions of the cardiac cycle in the Doppler waveform WD are detected, but adjustment of the Doppler waveform WD in step S13 may be performed automatically, triggered, for example, by the passage of a certain period of time, such as 2 seconds, from the time when generation of the Doppler waveform image UD began in step S12. In addition, when adjusting the Doppler waveform WD, in addition to adjusting the baseline position and the vertical axis scale of the Doppler waveform WD, the position of the Doppler gate DG may be readjusted so that the maximum and minimum values of the Doppler waveform WD fall within 70% of the vertical axis scale. Also, for example, step S13 can be omitted. However, it is preferable to perform step S12 because adjusting the Doppler waveform WD improves the accuracy of the blood flow velocity calculated by the blood flow velocity calculation unit 15 and improves the accuracy of the blood flow measured by the blood flow measurement unit 16.

[0102] Furthermore, in step S14, the current time point being in the diastolic phase P2 of the subject's heart is used as a trigger to proceed to the next step S15, but the trigger for proceeding from step S14 to step S15 is not limited to this. For example, instead of determining whether the current time point is in diastole P2, it may be determined whether the current time point is in systole P1. In this case, if it is determined that the current time point is not in systole P1, it is determined again whether the current time point is in systole P1, and if it is determined that the current time point is in systole P1, the process proceeds to the next step S15. However, because the amount of change in the Doppler waveform WD is smaller in diastole P2 than in systole P1, it is preferable to use the current time point being in diastole P2 as the trigger for proceeding to step S15 rather than the current time point being in systole P1.

[0103] Also, for example, instead of performing step S14, the process may proceed to step S15 when a certain period of time, such as two seconds, has elapsed since the operation of adjusting the Doppler waveform WD in step S13 is completed. Also, for example, instead of performing step S14, the process may proceed to step S15 when the start and end points of two or three or more cardiac cycles are detected in the Doppler waveform WD as a trigger.

[0104] Furthermore, when the B-mode image UB and Doppler waveform image UD are frozen and displayed on the display device 9 in step S15, the Doppler waveform image UD can be scrolled back and displayed so that the end point of the diastole P2 or the end point of the systole P1 in the Doppler waveform WD is aligned with, for example, the right end of the Doppler waveform image UD. In this way, by changing the position of the Doppler waveform WD displayed on the display device 9 after the B-mode image UB and Doppler waveform image UD are frozen and displayed, the time phase of the B-mode image UB displayed on the display device 9 can be aligned with the diastole P2 or the systole P1.

[0105] Furthermore, although the blood vessel running angle BA is estimated in step S8 after it is determined in step S7 that the second blood vessel diameter DS has a value within the predetermined range, the processing of step S8 may be performed between steps S5 and S7. In this way, the timing of estimating the blood vessel running angle BA is not particularly limited as long as it is performed before the processing of steps S9 to S11.

[0106] In step S6, the second blood vessel diameter calculation unit 13 calculates the distance in the depth direction D1 between the blood vessel anterior wall W1 and the blood vessel posterior wall W2 detected in step S5 as the second blood vessel diameter DS. However, for example, by performing the process of estimating the blood vessel running angle BA in step S8 before performing the process of calculating the second blood vessel diameter DS in step S6, the search line SL2 can be reset in a direction perpendicular to the blood vessel gradient line BL shown in Fig. 6, and the blood vessel diameter in the direction perpendicular to the running direction of the blood vessel B can be calculated as the second blood vessel diameter DS. This allows the second blood vessel diameter DS to be calculated more accurately, thereby improving the measurement accuracy of the blood flow rate.

[0107] Furthermore, in step S8, the second vascular wall detection unit 12 estimates the gradient of the blood vessel based on both the anterior vascular wall W1 and the posterior vascular wall W2, but can also estimate a virtual vascular gradient line BL representing the gradient of the blood vessel based on either the anterior vascular wall W1 or the posterior vascular wall W2.

[0108] Furthermore, although the Doppler steer angle is set in step S10 after the B-mode steering angle is set in step S9, and the Doppler gate DG is set in step S11 after the Doppler steering angle is set, the order in which steps S9 to S11 are performed is not particularly limited and can be interchanged. For example, after the B-mode steering angle is set in step S9, the Doppler steer angle setting in step S10 and the Doppler gate DG setting in step S11 can be performed in parallel. Also, for example, the processing of steps S9 to S11 can be performed in the order of setting the Doppler steer angle in step S10, setting the Doppler gate DG in step S11, and setting the B-mode steering angle in step S9.

[0109] Furthermore, in step S10, the second vascular wall detection unit 12 sets the Doppler tear angle so that the angle correction value for the blood vessel running angle BA is within 60 degrees. Alternatively, the blood vessel running angle BA can be set as the angle correction value for the Doppler tear angle. In this case, there is a risk that the angle correction value for the Doppler tear angle may exceed 60 degrees. However, when the angle correction value for the Doppler tear angle exceeds 60 degrees, information indicating that the angle correction value exceeds 60 degrees can be displayed on the display device 9. For example, the user can confirm the information indicating that the angle correction value exceeds 60 degrees and adjust the inclination of the ultrasound probe 21 in contact with the subject, thereby allowing the ultrasound diagnostic device 1 to automatically measure the blood flow velocity again.

[0110] Furthermore, after the Doppler gate DG is set in step S11, the vascular region BR including the Doppler gate DG in the B-mode image UB can be enlarged and displayed on the display device 9. This allows the vascular region BR to be clearly confirmed on the enlarged B-mode image UB. In this case, the vascular diameter is measured based on the enlarged B-mode image UB. For example, due to the resolution of the B-mode image UB, the position of the vascular wall can be detected more accurately by detecting the vascular wall based on the enlarged B-mode image UB than by detecting the vascular wall based on the B-mode image UB before enlargement. Therefore, by measuring the vascular diameter based on the enlarged B-mode image UB, the measurement accuracy of the blood flow rate can be improved.

[0111] Furthermore, although not shown, the ultrasound diagnostic device 1 may be provided with a guide unit for providing guidance to the user, and in step S1, the guide unit may display a message on the display device 9 instructing the user to align the short-axis image of the blood vessel B within the search region R1. This improves the accuracy with which the first vascular wall detection unit 10 recognizes the short-axis image of the blood vessel B, enabling the search line SL to be set at a more appropriate position. This allows the blood vessel diameter and cross-sectional area to be calculated with high accuracy, improving the measurement accuracy of the blood flow rate.

[0112] In this case, similarly, in step S4, a message to align the long-axis image of blood vessel B within search region R2 can be displayed on display device 9. This improves the accuracy with which second vascular wall detection unit 12 recognizes the long-axis image of blood vessel B.

[0113] It is generally known that the blood vessel diameter periodically changes between a minimum diameter and a maximum diameter in accordance with the heartbeat. Therefore, although not shown, the second blood vessel diameter calculation unit 13 can superimpose on the B-mode image UB a graph showing the change over time in the second blood vessel diameter DS calculated for the B-mode image UB including a long-axis image corresponding to a longitudinal cross section passing through the center of the blood vessel B, i.e., the second blood vessel diameter DS corresponding to the diameter of the blood vessel B, and display the graph on the display device 9. This allows the user to easily grasp the change over time in the second blood vessel diameter DS corresponding to the diameter of the blood vessel B.

[0114] Furthermore, by obtaining information on the time change of the second vascular diameter DS corresponding to the diameter of blood vessel B, the minimum and maximum diameters of blood vessel B in the long-axis image can be easily measured. Therefore, for example, the ultrasound diagnostic device 1 can be provided with an elasticity index calculation unit (not shown) that measures the minimum and maximum diameters of blood vessel B based on information on the time change of the second vascular diameter DS corresponding to the diameter of blood vessel B and calculates an elasticity index representing the elasticity of the blood vessel based on the measured minimum and maximum diameters. The elasticity index calculation unit can calculate, for example, the difference between the maximum and minimum diameters of the blood vessel as the elasticity index. Furthermore, the elasticity index calculation unit can calculate the difference between the maximum and minimum diameters of the blood vessel by dividing it by the minimum diameter of the blood vessel to normalize it and calculate the elasticity index as the elasticity index.

[0115] Furthermore, by using a blood pressure monitor (not shown) to measure the subject's blood pressure Q1 at the time when the blood vessel diameter is smallest and the subject's blood pressure Q2 at the time when the blood vessel diameter is largest, the elasticity index calculation unit can calculate the stiffness parameter X={Log(Q2 / Q1)} / {(DB / DA)-1} described in Japanese Patent No. 5384919 as the elasticity index using the blood pressures Q1, Q2, the minimum blood vessel diameter DA, and the maximum blood vessel diameter DB.

[0116] Embodiment 2 In step S12 of the operation of the ultrasound diagnostic apparatus 1 of embodiment 1, the B-mode image UB and the Doppler waveform image UD are generated in parallel, but it is also possible to temporarily stop the generation of the B-mode image UB and generate only the Doppler waveform image UD.

[0117] The operation of the ultrasound diagnostic apparatus 1 according to the second embodiment will be described below using the flowchart in Figure 20. This flowchart is the same as the flowchart of the first embodiment shown in Figure 14, except that steps S21 to S23 are added instead of step S12, and step S24 is added instead of step S15. Therefore, the description of the processes in steps S1 to S11 will be omitted.

[0118] In step S21 following step S11, continuous generation of B-mode images UB is started, and based on the value of the second vascular diameter DS determined to be within the range determined in step S7, it is determined whether the current time is in diastole P2 of the subject's heart. As shown in FIG. 21 , the vascular diameter generally fluctuates periodically between a minimum diameter DA and a maximum diameter DB in accordance with the heartbeat, with the maximum diameter DB being in systole P1 of the heart and the minimum diameter DA being in diastole P2 of the heart. Therefore, for example, by measuring the minimum diameter DA of the blood vessel, it is determined that the current time is in diastole P2 of the subject's heart. If it is determined that the current time is not in diastole P2 of the subject's heart, the process of step S21 is performed again. If it is determined that the current time is in diastole P2 of the subject's heart, the process proceeds to step S22.

[0119] In step S22, the B-mode image UB displayed on the display device 9 is frozen. In the following step S23, the Doppler processing unit 7 starts to continuously generate Doppler waveform images UD, and displays the generated Doppler waveform images UD on the display device 9. As a result, the Doppler waveform images UD are displayed on the display device 9 while the B-mode images UB are displayed in a frozen state.

[0120] Once the Doppler waveform image UD is displayed on the display device 9 in this way, the process proceeds to step S13, where adjustment of the Doppler waveform WD in the Doppler waveform image UD generated in step S23 is carried out. Next, in step S14, period information of the Doppler waveform WD is acquired, and based on the acquired period information, it is determined whether the current time point is in diastole P2 of the subject's heart. If it is determined that the current time point is not in diastole P2 of the subject's heart, the process of step S14 is performed again. If it is determined that the current time point is in diastole P2 of the subject's heart, the process proceeds to step S24.

[0121] In step S24, the Doppler waveform image UD displayed on the display device 9 is frozen. As a result, the B-mode image UB and the Doppler waveform image UD in the diastole P2 are frozen and displayed on the display device 9, and the Doppler data in the diastole P2, where the amount of change in the Doppler waveform WD is small, can be used to measure the blood flow rate.

[0122] In the following step S16, the blood flow rate in the vascular region BR is automatically measured based on the value of the second vascular diameter DS determined to be within the range determined in step S7 and the Doppler waveform image UD frozen and displayed in step S24. In step S17, the measured value MV of the blood flow rate is displayed on the display device 9 together with the B-mode image UB and the Doppler waveform image UD, as shown in FIG. 17. In this way, when the measured value MV of the blood flow volume is displayed on the display device 9, the operation of the ultrasonic diagnostic apparatus 1 ends.

[0123] As described above, according to the ultrasound diagnostic apparatus 1 of the second embodiment of the present invention, even when the generation of the B-mode image UB is temporarily stopped and only the Doppler waveform image UD is generated, the first blood vessel diameter DF is calculated based on the B-mode image UB representing a short-axis view of the blood vessel B, a B-mode image UB representing a long-axis view passing through the center of the blood vessel B is accurately acquired based on the first blood vessel diameter DF, and the blood flow rate is measured using the acquired B-mode image UB representing the long-axis view of the blood vessel B, just as in the case of simultaneously generating both the B-mode image UB and the Doppler waveform image UD in the first embodiment. Therefore, it is possible to reduce fluctuations in the measurement accuracy of the blood flow rate caused by the user adjusting the position of the ultrasound probe 21 on the body surface of the subject, and improve the measurement accuracy.

[0124] In step S21, the current time point being in the diastolic phase P2 of the subject's heart is used as a trigger to proceed to the next step S22, but the trigger for proceeding from step S21 to step S22 is not limited to this. For example, instead of determining whether the current time point is in diastole P2, it may be determined whether the current time point is in systole P1. In this case, if it is determined that the current time point is not in systole P1, it is determined again whether the current time point is in systole P1, and if it is determined that the current time point is in systole P1, the process proceeds to the next step S22. However, because the amount of change in the Doppler waveform WD is smaller in diastole P2 than in systole P1, it is preferable to use the current time point being in diastole P2 as the trigger for proceeding to step S22 rather than the current time point being in systole P1.

[0125] Also, for example, step S21 can be omitted. In this case, the setting of the Doppler gate DG on the B-mode image UB in step S11 triggers the display device 9 to freeze and display the B-mode image UB in step S22. Furthermore, the trigger for proceeding to step S22 can also be, for example, the passage of a certain period of time, such as two seconds, from the time when the setting of the Doppler gate DG in step S11 is completed.

[0126] Furthermore, a Doppler waveform image UD is generated in step S23, and the generated Doppler waveform image UD is displayed on the display device 9; however, as in step S12 in embodiment 1, the Doppler waveform image UD does not necessarily have to be displayed on the display device 9 as long as the data of the Doppler waveform WD is acquired.

[0127] Embodiment 3 The ultrasonic diagnostic device 1 of the first embodiment has a configuration in which the display device 9, the input device 18, and the ultrasonic probe 21 are directly connected to the processor 22. However, for example, the display device 9, the input device 18, the ultrasonic probe 21, and the processor 22 can also be indirectly connected via a network.

[0128] 22, an ultrasonic diagnostic apparatus 1A according to the third embodiment has a display device 9, an input device 18, and an ultrasonic probe 21 connected to an ultrasonic diagnostic apparatus main body 41 via a network NW. The ultrasonic diagnostic apparatus main body 41 is the ultrasonic diagnostic apparatus 1 according to the first embodiment shown in FIG. 1 except that the display device 9, the input device 18, and the ultrasonic probe 21 are removed, and the ultrasonic diagnostic apparatus main body 41 is composed of a transmission / reception circuit 5, a storage unit 19, and a processor 22.

[0129] Even when the ultrasound diagnostic device 1A has such a configuration, similar to the ultrasound diagnostic device 1 of the first embodiment, a first blood vessel diameter DF is calculated based on a B-mode image UB representing a short-axis image of blood vessel B, a B-mode image UB representing a long-axis image passing through the center of blood vessel B is accurately acquired based on the first blood vessel diameter DF, and the blood flow rate is measured using the acquired B-mode image UB representing the long-axis image of blood vessel B. Therefore, it is possible to reduce fluctuations in the measurement accuracy of the blood flow rate caused by the user adjusting the position of the ultrasound probe 21 on the body surface of the subject, thereby improving the measurement accuracy.

[0130] Furthermore, since the display device 9, input device 18, and ultrasound probe 21 are connected to the ultrasound diagnostic device main body 41 via the network NW, the ultrasound diagnostic device main body 41 can be used as a so-called remote server. This allows, for example, a user to diagnose a subject by having the display device 9, input device 18, and ultrasound probe 21 at hand, thereby improving the convenience of ultrasound diagnosis. Furthermore, for example, when a portable thin computer known as a tablet is used as the display device 9 and input device 18, the user can more easily perform ultrasound diagnosis of the subject, further improving the convenience of ultrasound diagnosis.

[0131] The display device 9, the input device 18, and the ultrasonic probe 21 are connected to the ultrasonic diagnostic device main body 41 via the network NW. In this case, the display device 9, the input device 18, and the ultrasonic probe 21 may be connected to the network NW by wire or wirelessly. Furthermore, although the fourth embodiment has been described as being applicable to the first embodiment, it can also be applied to the second embodiment in the same manner. [Explanation of symbols]

[0132] 1, 1A ultrasound diagnostic device, 2 transducer array, 3 transmission circuit, 4 reception circuit, 5 transmission / reception circuit, 6 B-mode processing unit, 7 Doppler processing unit, 8 display control unit, 9 display device, 10 first blood vessel wall detection unit, 11 first blood vessel diameter calculation unit, 12 second blood vessel wall detection unit, 13 second blood vessel diameter calculation unit, 14 gate setting unit, 15 blood flow velocity calculation unit, 16 blood flow measurement unit, 17 device control unit, 18 input device, 19 storage unit, 21 ultrasound probe, 22 processor, 23 amplifier unit, 24 AD conversion unit, 25 beamformer, 26 signal processing unit, 27 DSC, 28 image processing unit, 29 quadrature detection unit, 30 high-pass filter, 31 fast Fourier transform unit, 32 Doppler waveform image generation unit, 33 data memory, 41 ultrasound diagnostic device main body, A1, B1, B2, H angle, AL, JL line, B blood vessel, BA Vessel angle, BR vessel area, BL vessel gradient line, C midpoint, E estimation error, D1 depth direction, D2 lateral direction, DA minimum diameter, DB maximum diameter, DF first vessel diameter, DG Doppler gate, DS second vessel diameter, G1, G2, G3, G4 graph, J1, J2, J3, J4 depth, K1, K2 brightness threshold, L1, L2 difference, L1M maximum value, LG gate width, M1, M2, M3, M4 measurement point marker, MV1, MV2 measurement value, NW network, P1 systole, P2 diastole, R1, R2 search area, SL1, SL2 search line, UB B-mode image, UD Doppler waveform image, W1 anterior vessel wall, W2 posterior vessel wall, WD Doppler waveform, X1, X1M, X2, X2M, X3, X4 points.

Claims

1. a transducer array that transmits and receives ultrasonic waves to and from the subject to obtain a received signal; a B-mode processing unit that generates a B-mode image in which at least blood vessels are imaged based on the received signal; a display device that displays the B-mode image generated by the B-mode processing unit; a first vascular wall detection unit that detects a vascular wall in a short-axis direction by analyzing the B-mode image in which a short-axis image of the blood vessel is captured; a first blood vessel diameter calculation unit that calculates a first blood vessel diameter based on the blood vessel wall in the short axis direction detected by the first blood vessel wall detection unit; a second vascular wall detection unit that detects a vascular wall in a longitudinal direction by analyzing the B-mode image in which a longitudinal image of the blood vessel is captured; a second blood vessel diameter calculation unit that calculates a second blood vessel diameter based on the blood vessel wall in the longitudinal axis direction detected by the second blood vessel wall detection unit; a gate setting unit that sets a Doppler gate within the blood vessel on the B-mode image in which the long-axis image is captured; a Doppler processing unit that acquires Doppler data within the Doppler gate; a blood flow velocity calculation unit that calculates a blood flow velocity based on the Doppler data; a blood flow measurement unit that measures the blood flow rate based on the detected blood vessel wall in the long axis direction or the blood vessel wall in the short axis direction and the calculated blood flow velocity; Equipped with the second blood vessel diameter calculation unit determines whether the second blood vessel diameter has a value within a range defined for the first blood vessel diameter; an ultrasound diagnostic device that automatically transitions to measuring the blood flow rate when the calculated second blood vessel diameter remains within a predetermined range with respect to the calculated first blood vessel diameter over a predetermined number of frames.

2. The second vascular wall detection unit setting a search line on the B-mode image for searching the vascular wall in the longitudinal direction; 2. The ultrasonic diagnostic apparatus according to claim 1, wherein the anterior wall and posterior wall of the blood vessel are detected as the blood vessel wall in the longitudinal direction based on a brightness profile of the B-mode image on the set search line.

3. The ultrasonic diagnostic apparatus according to claim 2 , wherein the second vascular wall detector sets detection point markers on the detected anterior and posterior vascular walls, and displays the markers on the display device.

4. 4. The ultrasonic diagnostic apparatus according to claim 2, wherein the gate setting unit sets the Doppler gate having a center position and a size determined based on the coordinates of the anterior wall and the posterior wall of the blood vessel detected by the second vascular wall detection unit.

5. 5. The ultrasound diagnostic device according to claim 2, wherein the second vascular wall detection unit estimates a vascular running angle based on at least one of the detected anterior vascular wall and the posterior vascular wall, and sets a Doppler stear angle so that an angle correction value for the vascular running angle is within 60 degrees.

6. 6. The ultrasonic diagnostic apparatus according to claim 5, wherein the B-mode processor generates the B-mode image based on a B-mode steering angle set in accordance with the blood vessel running angle estimated by the second blood vessel wall detector.

7. the Doppler processing unit generates a Doppler waveform image based on the Doppler data; 7. The ultrasound diagnostic apparatus according to claim 1, wherein the display device displays both the B-mode image generated by the B-mode processing unit and the Doppler waveform image generated by the Doppler processing unit.

8. the Doppler processing unit generates a Doppler waveform image in parallel with the generation of the B-mode image by the B-mode processing unit; 8. The ultrasonic diagnostic apparatus according to claim 7, wherein both the B-mode image and the Doppler waveform image are frozen and the blood flow rate is measured by the blood flow rate measuring unit.

9. the Doppler processing unit acquires Doppler data in the Doppler gate after the B-mode image is frozen, and generates a Doppler waveform image; 8. The ultrasonic diagnostic apparatus according to claim 7, wherein the Doppler waveform image is frozen and the blood flow rate is measured by the blood flow rate measuring unit.

10. generating a B-mode image in which at least blood vessels are imaged based on a received signal obtained by transmitting and receiving ultrasonic waves to and from the subject; Displaying the B-mode image; detecting a vascular wall in the short axis direction by analyzing a short axis image of the blood vessel captured in the B-mode image; calculating a first blood vessel diameter based on the detected blood vessel wall in the short axis direction; Detecting a blood vessel wall in the longitudinal direction by analyzing the B-mode image in which a longitudinal image of the blood vessel is captured; calculating a second blood vessel diameter based on the detected blood vessel wall in the longitudinal direction; a Doppler gate is set in the blood vessel on the B-mode image in which the long-axis image is captured, when the calculated second blood vessel diameter is maintained within a predetermined range with respect to the calculated first blood vessel diameter over a predetermined number of frames; acquiring Doppler data within the Doppler gate; calculating a blood flow velocity based on the Doppler data; A method for controlling an ultrasonic diagnostic apparatus that measures blood flow based on the detected blood vessel wall in the long axis direction or the detected blood vessel wall in the short axis direction and the calculated blood flow velocity.

11. generating a B-mode image in which at least blood vessels are imaged based on a received signal obtained by transmitting and receiving ultrasonic waves to and from the subject; Displaying the B-mode image; detecting a vascular wall in the short axis direction by analyzing a short axis image of the blood vessel captured in the B-mode image; calculating a first blood vessel diameter based on the detected blood vessel wall in the short axis direction; Detecting a blood vessel wall in the longitudinal direction by analyzing the B-mode image in which a longitudinal image of the blood vessel is captured; calculating a second blood vessel diameter based on the detected blood vessel wall in the longitudinal direction; a Doppler gate is set in the blood vessel on the B-mode image in which the long-axis image is captured, when the calculated second blood vessel diameter is maintained within a predetermined range with respect to the calculated first blood vessel diameter over a predetermined number of frames; acquiring Doppler data within the Doppler gate; calculating a blood flow velocity based on the Doppler data; A processor for an ultrasonic diagnostic device that measures the blood flow rate based on the detected blood vessel wall in the long axis direction or the blood vessel wall in the short axis direction and the calculated blood flow velocity.

Images