JP2014188161A - Ultrasound diagnosis apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To upgrade precision in measurement of a vascular diameter using an ultrasound diagnosis system.SOLUTION: In Fig.5 (A), a B-mode image 24R acquired at rest is shown. A reference marker M is produced with the B-mode image 24R as a tomographic image of a reference time phase. In Fig.5 (B), a B-mode image that is sequentially formed over plural time phases is shown. In the Fig.5 (B), a position of a blood vessel BV is deviated from a position at rest. In the case of a state shown in the Fig.5 (B), a user adjusts the position of a probe while looking at the B-mode image 24 so that the reference marker M will overlap a front wall FW and back wall BW of the blood vessel BV. Accordingly, a position at which a vascular diameter is measured is corrected. Preferably, the vascular diameter can be measured at the same position as the position at rest.

Description

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

  In the evaluation of blood vessel function, for example, blood flow responsive vasodilation (FMD) is known as a method for evaluating vascular endothelial function. Vascular endothelial function measurement by FMD is considered useful for evaluation of endothelial function of blood vessels and diagnosis of arteriosclerosis. The general measurement procedure of FMD is as follows.

  First, the diameter of the brachial artery blood vessel is measured when the subject is at rest, and then the forearm portion of the subject is driven with a cuff or the like for about 5 minutes. Thereafter, when the blood transfusion is released, the blood vessel diameter of the brachial artery is expanded and gradually returns to the blood vessel diameter at rest. Then, the endothelial function of the brachial artery is evaluated from the change in the diameter of the blood vessel after the release of blood pressure and the state of the blood vessel at rest.

  In the evaluation of vascular endothelial function by FMD, an ultrasonic diagnostic apparatus can be used for measuring a vascular diameter (see, for example, Patent Document 1). In other words, the position of the blood vessel wall at rest, during blood excitement, and after release of blood transfusion is tracked by the ultrasonic diagnostic apparatus, and, for example, the blood vessel diameter at rest and the blood vessel diameter after release of blood transfusion are compared.

  In the FMD, when comparing the resting blood vessel diameter and the blood vessel diameter after releasing the blood transfusion, it is desirable to measure the blood vessel diameter at the same site at rest and after releasing the blood transfusion. However, when the cuff is released for releasing the blood transfusion, for example, the forearm portion moves, and there is a possibility that the measurement position of the blood vessel diameter at the time of resting and after the blood release is canceled is shifted.

Japanese Patent No. 4778725

  In view of the background art described above, the inventor of the present application has conducted research and development on a technique for improving accuracy of blood vessel evaluation using an ultrasonic diagnostic apparatus, for example, accuracy of blood vessel endothelial function evaluation.

  The present invention has been made in the course of its research and development, and its purpose is to increase the measurement accuracy of the blood vessel diameter using an ultrasonic diagnostic apparatus.

  An ultrasonic diagnostic apparatus suitable for the above-described object includes a probe that transmits and receives ultrasonic waves to and from a blood vessel, a transmission / reception unit that obtains an echo signal by controlling the probe, and an ultrasonic image of the blood vessel based on the echo signal. An ultrasound image forming unit; a blood vessel wall specifying unit that specifies a position of a blood vessel wall based on an echo signal; a blood vessel diameter measuring unit that obtains blood vessel diameter measurement data based on the position of the blood vessel wall; A reference marker generating unit that generates a reference marker indicating a characteristic position in the sound image, and a display image forming unit that forms a display image in which the reference marker is superimposed on an ultrasonic image obtained over a plurality of time phases. It is characterized by that.

  In the above configuration, the blood vessel diameter measurement data is obtained based on, for example, the position of the blood vessel wall (front wall) on the side close to the probe and the position of the blood vessel wall (rear wall) on the side far from the probe. For example, the distance between the front wall and the rear wall is measured data. The reference time phase is a time phase for obtaining a blood vessel diameter serving as a reference when measuring the blood vessel diameter over a plurality of time phases. For example, blood flow reactive vasodilation (FMD: Flow Mediated Dilatation) In the measurement of the blood vessel diameter in), the time phase at rest is set as the reference time phase. The reference marker is set at a characteristic position in the reference time phase ultrasonic image, for example, a position of a blood vessel wall of a blood vessel to be measured or a tissue in the vicinity of the blood vessel.

  According to the ultrasonic diagnostic apparatus, since a display image in which a reference marker is superimposed on an ultrasonic image obtained over a plurality of time phases is formed, a user (measurer) can perform a reference time phase from the display image. The deviation between the feature position and the feature position in the current phase can be visually confirmed. Therefore, for example, the user can correct the deviation of the characteristic position by adjusting the position of the probe while looking at the display image, the deterioration of the measurement accuracy due to the deviation is suppressed, and the measurement accuracy of the blood vessel diameter is increased.

  In a preferred specific example, the reference marker generation unit generates a reference marker indicating a characteristic position of at least one of a blood vessel and another tissue in a reference time phase ultrasonic image.

  In a preferred specific example, the reference marker generation unit generates a reference marker based on a plurality of feature points set by a user in an ultrasonic image of a reference time phase.

  In a preferred specific example, the reference marker generation unit generates a reference marker in which a plurality of feature points are connected by lines.

  In a preferred specific example, the reference marker generation unit generates a reference marker that connects two feature points with a straight line in a set order for a plurality of feature points that are sequentially set one by one. .

  In a preferred specific example, the reference marker generation unit generates a polygonal reference marker having each of a plurality of feature points as vertices.

  According to the present invention, blood vessel diameter measurement accuracy using an ultrasonic diagnostic apparatus can be increased. For example, according to a preferred aspect of the present invention, the user can correct the deviation of the characteristic position by adjusting the position of the probe while viewing the display image, and the deterioration of the measurement accuracy caused by the deviation can be suppressed. Diameter measurement accuracy is increased.

1 is a functional block diagram showing an overall configuration of a preferable ultrasonic diagnostic apparatus of the present invention. It is a figure for demonstrating an echo tracking process. It is a figure which shows the specific example of a reference | standard marker. It is a flowchart which shows the setting process of several feature points. It is a figure which shows the specific example 1 of the display image containing a reference | standard marker. It is a figure which shows the specific example 2 of the display image containing a reference | standard marker.

  FIG. 1 is a functional block diagram showing an overall configuration of an ultrasonic diagnostic apparatus suitable for implementing the present invention. The probe 10 includes a plurality of vibration elements that transmit and receive ultrasonic waves to and from a blood vessel. In the ultrasonic diagnostic apparatus of FIG. 1, the probe 10 is desirably a linear scanning probe, but a probe having another scanning mode may be used depending on, for example, the application.

  The transmission / reception unit 12 controls transmission of a plurality of vibration elements included in the probe 10 to form a transmission beam, and scans the transmission beam within a diagnostic region including a blood vessel. That is, the transmission / reception unit 12 has a function of a transmission beamformer.

  In addition, the transmission / reception unit 12 forms a reception beam by performing phasing addition processing on a plurality of reception signals obtained from the plurality of vibration elements, and generates a reception beam signal (echo signal) from within the diagnosis region along the reception beam. collect. That is, the transmission / reception unit 12 also has a function of a reception beamformer. The reception beam signal obtained in the transmission / reception unit 12 is output to the tomographic image forming unit 20 and the blood vessel wall specifying unit 30.

  The tomographic image forming unit 20 forms a tomographic image of the blood vessel based on the received beam signal. For example, the tomographic image forming unit 20 forms a B-mode image of a blood vessel for each time phase over a plurality of time phases. The B-mode images formed one after another over a plurality of time phases are subjected to display processing in the display image forming unit 50 and displayed on the display unit 52. The tomographic image (image data) formed in the tomographic image forming unit 20 is stored in the memory 22 in all or part of a plurality of time phases.

  The blood vessel wall specifying unit 30 specifies the position of the blood vessel wall based on the received beam signal. The blood vessel wall specifying unit 30 tracks the position of the blood vessel wall over a plurality of time phases by, for example, echo tracking processing. The echo tracking process will be described below with reference to the reference numerals shown in FIG.

  FIG. 2 is a diagram for explaining the echo tracking process. FIG. 2 shows a specific example of the B-mode image 24 of the blood vessel BV. An electrocardiographic waveform E may be displayed in the B-mode image 24.

  In the echo tracking process, the beam cursor BC is set in the B-mode image 24, and the position of the blood vessel wall is tracked on the ultrasonic beam corresponding to the position of the beam cursor BC. For example, the user (measurer) may set the beam cursor BC at a desired position (line), or the blood vessel wall specifying unit 30 may set the beam cursor BC at a specified position.

  The blood vessel wall specifying unit 30 detects the front wall FW located on the probe 10 side and the rear wall BW located far from the probe 10 on the ultrasonic beam corresponding to the position (line) of the beam cursor BC. In transmitting and receiving ultrasonic waves, a relatively strong reflected wave is acquired from the blood vessel wall. Accordingly, the received beam signal obtained along the beam cursor BC is acquired with a relatively large amplitude in the portions corresponding to the front wall FW and the rear wall BW.

  In the echo tracking process, the zero-cross point is detected as a representative point in the received beam signal with a relatively large amplitude corresponding to the blood vessel wall, and the detected zero-cross point is tracked to greatly improve the extraction accuracy. Yes. The zero cross point is detected as the timing at which the polarity of the received beam signal is inverted from positive to negative or from negative to positive within the period of the tracking gate TG. When the zero-cross point is detected, the tracking gate TG of the next time phase is set around that point. In the next time phase, the zero cross point is detected within the newly set period of the tracking gate TG. In this manner, the zero cross point is tracked over a plurality of time phases for each of the front wall FW and the rear wall BW.

  Returning to FIG. 1, the blood vessel diameter measuring unit 32 measures the blood vessel diameter, which is the distance between the front wall and the rear wall, based on the positions of the front wall and the rear wall of the blood vessel specified by the blood vessel wall specifying unit 30. To do. The positions of the front wall and the rear wall of the blood vessel, that is, the zero cross point corresponding to the front wall and the zero cross point corresponding to the rear wall are tracked by the blood vessel wall specifying unit 30 over a plurality of time phases. The blood vessel diameter measuring unit 32 measures a blood vessel diameter that is a distance between the front wall and the rear wall, that is, a distance between two zero cross points, over a plurality of time phases.

  In measuring vascular endothelial function by blood flow responsive dilatation (FMD), for example, first, the diameter of the brachial artery at rest of the subject is measured, and then the forearm portion of the subject is measured. Drive with cuffs for about 5 minutes. Thereafter, when the blood transfusion is released, the blood vessel diameter of the brachial artery is expanded and gradually returns to the blood vessel diameter at rest. Then, the endothelial function of the brachial artery is evaluated from the change in the diameter of the blood vessel after the release of blood pressure and the state of the blood vessel at rest.

  In the evaluation of vascular endothelial function by FMD, the vascular wall specifying unit 30 determines that the front wall extends over a plurality of time phases in a measurement period from resting to several minutes (or more) after releasing the blood transfusion. And track the position of the rear wall. Then, the blood vessel diameter measuring unit 32 measures the blood vessel diameter that is the distance between the front wall and the rear wall over a plurality of time phases within the measurement period. For example, the blood vessel diameter measuring unit 32 generates a blood vessel diameter changing waveform representing a value of the blood vessel diameter that changes every moment, and outputs it to the display image forming unit 50. The blood vessel diameter change waveform output to the display image forming unit 50 is displayed on the display unit 52.

  The reference marker generation unit 40 generates a reference marker indicating the feature position in the tomographic image of the reference time phase stored in the memory 22. In the evaluation of vascular endothelial function by FMD, a B-mode image at rest is stored in the memory 22, and the B-mode image at rest is a tomographic image of the reference time phase. The reference marker generation unit 40 generates a reference marker that indicates the characteristic position of the blood vessel in the B-mode image at rest. For example, a reference marker indicating the position of the blood vessel wall is generated. The generation of the reference marker will be described below with reference to the reference numerals shown in FIG.

  FIG. 3 is a diagram illustrating a specific example of the reference marker. FIG. 3 shows a B-mode image 24R when the blood vessel BV is at rest. The reference marker generator 40 generates a reference marker M based on a plurality of feature points (P1 to P6) set in the B-mode image 24R at rest.

  The positions of the plurality of feature points (P1 to P6) are designated by the user. For example, a B-mode image 24R at rest is displayed on the display unit 52, and the user views the positions of the front wall FW and the rear wall BW of the blood vessel BV while viewing the B-mode image 24R at rest displayed on the display unit 52. A plurality of feature points (P1 to P6) are set. The user designates the positions of a plurality of feature points (P1 to P6) in the B-mode image 24R using the operation device 42 such as a mouse or a trackball.

  FIG. 4 is a flowchart showing a process for setting a plurality of feature points. First, a B-mode image at rest is displayed on the display unit 52 (S401), and feature points are initialized (S402). In the initialization of the feature points, for example, data such as the previously set feature point positions are cleared, and a new feature point can be set.

  Then, the user designates the position of one feature point at, for example, a blood vessel wall by using the operation device 42 while viewing the B-mode image at rest displayed on the display unit 52 (S403). Note that feature points may be specified at positions of other tissues existing near the blood vessel.

  When the position of one feature point is designated, the reference marker generation unit 40 confirms whether or not the designated position meets a condition as a feature point (S404). Received beam signals obtained from blood vessels and tissues have relatively large echo values (luminance values). Therefore, the reference marker generation unit 40 calculates the average value of echo values in a predetermined local area centered on the position designated by the user, and if the average value is equal to or greater than a threshold value, for example, It is determined that a feature point has been designated at the location, and it is determined that the condition is met.

  In the region including the boundary between blood vessels and tissues, the echo value varies relatively spatially. Therefore, the reference marker generation unit 40 has a feature point at a blood vessel or tissue location based on the dispersion value of the echo value and the gradient of the echo value within a predetermined local region centered on the position designated by the user. It may be determined whether or not it is designated, that is, whether or not the condition is met.

  If it is determined in S404 that the specified position does not meet the conditions, an error message is displayed on the display unit 52 (S405), the user respecifies the position of the feature point (S403), and the reference marker generating unit 40 It is confirmed whether or not the designated position meets the condition as a feature point (S404). The processes from S403 to S405 are repeatedly executed until the conditions are met.

  If it is determined in S404 that the designated position matches the condition, one feature point is set at the designated position that meets the condition (S406), and the set feature point is displayed on the display unit 52.

  Then, the reference marker generation unit 40 checks whether or not the number of feature points has reached a predetermined number (S407). For example, if the number of feature points is designated, it is confirmed whether or not the designated number has been reached. The user may be allowed to specify the number of feature points, or it may be determined that the feature points have reached a predetermined number when the user performs an end operation.

  Thus, the processing from S403 to S407 is repeatedly executed until it is determined in S407 that the feature points have reached the predetermined number, and when it is determined in S407 that the feature points have reached the predetermined number, this flowchart is ended.

  Returning to FIG. 3, when a predetermined number of feature points are set, for example, when all of the six feature points (P1 to P6) are set, the reference marker generation unit 40 sets the six feature points (P1 to P6). ) To generate a reference marker M. For example, as illustrated in FIG. 3, the reference marker generation unit 40 generates a reference marker M in which six feature points (P1 to P6) are connected by lines.

  For example, the reference marker generation unit 40 generates a reference marker M by connecting two feature points in a set order with a straight line with respect to a plurality of feature points set in order one by one. That is, when the six feature points are set in the order of P1, P2, P3, P4, P5, and P6, the reference marker generation unit 40 makes a straight line between P1 and P2 when P2 is set next to P1. When P3 is set, P2 and P3 are connected with a straight line. When P4 is set, P3 and P4 are connected with a straight line. When P5 is set, P4 and P5 are connected. When P6 is set, P5 and P6 are connected by a straight line, and P6 and P1 are further connected by a straight line to generate a polygonal reference marker M shown in FIG.

  The reference marker generation unit 40 may generate, for example, a polygonal reference marker M having vertices at six feature points (P1 to P6) after all feature points are set. At that time, the reference marker generation unit 40 may use a known algorithm that draws a polygon by connecting a plurality of points.

  Returning to FIG. 1, the display image forming unit 50 superimposes the reference marker generated by the reference marker generating unit 40 on the B-mode image formed one after another over a plurality of time phases in the tomographic image forming unit 20. A display image is formed. The formed display image is displayed on the display unit 52. A specific example of a display image will be described below with reference to the reference numerals shown in FIG.

  FIG. 5 is a diagram illustrating a specific example 1 of a display image including a reference marker. FIG. 5A shows a B-mode image 24R at rest, and the reference marker M is generated using the B-mode image 24R as a reference time phase tomographic image.

  FIG. 5B shows a B-mode image 24 formed one after another over a plurality of time phases. The B-mode image 24 in FIG. 5B is a tomographic image after the cuff is released in the vascular endothelial function evaluation by FMD, for example. In FIG. 5B, for example, the forearm portion of the subject moves, and the position of the blood vessel BV is deviated from the resting position.

  Therefore, the reference marker M set at the positions of the front wall FW and the rear wall BW of the blood vessel BV in FIG. 5A is shifted from the blood vessel BV in the B-mode image 24 of FIG. Yes.

  In the state shown in FIG. 5B, the user (measuring person) sees the B-mode image 24 shown in FIG. 5B displayed on the display unit 52 while the reference marker M is shown in FIG. As described above, the position of the probe 10 is adjusted so as to overlap the front wall FW and the rear wall BW of the blood vessel BV. Thereby, the position where the blood vessel diameter is measured is corrected, and preferably, the blood vessel diameter can be measured at the same position as at rest.

  FIG. 6 is a diagram illustrating a specific example 2 of the display image including the reference marker. FIG. 6A shows a B-mode image 24R at rest, and the reference markers M1 and M2 are generated using the B-mode image 24R as a reference time phase tomographic image. The reference marker M1 shown in FIG. 6A is a boundary line between the front wall FW and the rear wall BW at rest, and the reference marker M2 is set at the position of another tissue in the vicinity of the blood vessel BV.

  In the B-mode image 24R, the reference marker generation unit 40 detects the boundary of the front wall FW and the boundary of the rear wall BW, for example, based on the magnitude of the echo value, and generates the reference marker M1. For example, the reference marker generation unit 40 detects a tissue having a relatively large echo value in the B-mode image 24R, and generates a reference marker M2 corresponding to the position of the tissue.

  FIG. 6B shows a B-mode image 24 formed one after another over a plurality of time phases. A B-mode image 24 in FIG. 6B is a tomographic image after the cuff is released in the vascular endothelial function evaluation by FMD, for example, and the position of the blood vessel BV is deviated from the resting position.

  Therefore, the reference marker M1 set at the positions of the front wall FW and the rear wall BW of the blood vessel BV in FIG. 6A is shifted from the blood vessel BV in the B-mode image 24 of FIG. 6B. Yes. Further, the reference marker M2 set for the tissue in FIG. 6A is shifted from the position of the tissue in the B-mode image 24 of FIG. 6B.

  In the case of the state shown in FIG. 6B, the user (measurer) looks at the B-mode image 24 of FIG. 6B displayed on the display unit 52 while the reference marker M1 is shown in FIG. Thus, the position of the probe 10 is adjusted so that the front wall FW and the rear wall BW of the blood vessel BV overlap, and the reference marker M2 overlaps the tissue as shown in FIG. Thereby, the position where the blood vessel diameter is measured is corrected, and preferably, the blood vessel diameter can be measured at the same position as at rest.

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

  DESCRIPTION OF SYMBOLS 10 Probe, 12 Transmission / reception part, 20 Tomographic image formation part, 22 Memory, 30 Blood vessel wall specific | specification part, 32 Blood vessel diameter measurement part, 40 Reference marker production | generation part, 42 Operation device, 50 Display image formation part, 52 Display part.

Claims (6)

A probe that transmits and receives ultrasound to and from a blood vessel;
A transmitter / receiver for controlling the probe to obtain an echo signal;
An ultrasound image forming unit that forms an ultrasound image of a blood vessel based on an echo signal;
A blood vessel wall specifying unit for specifying the position of the blood vessel wall based on the echo signal;
A blood vessel diameter measurement unit that obtains blood vessel diameter measurement data based on the position of the blood vessel wall;
A reference marker generating unit that generates a reference marker indicating a feature position in the ultrasonic image of the reference time phase;
A display image forming unit that forms a display image in which the reference marker is superimposed on an ultrasonic image obtained over a plurality of time phases;
Having
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 1,
The reference marker generation unit generates a reference marker indicating a characteristic position of at least one of a blood vessel and another tissue in an ultrasonic image of a reference time phase.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 1 or 2,
The reference marker generation unit generates a reference marker based on a plurality of feature points set by a user in an ultrasonic image of a reference time phase.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 3.
The reference marker generation unit generates a reference marker connecting a plurality of feature points with lines,
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 4,
The reference marker generation unit generates a reference marker that connects two feature points with a straight line in a set order with respect to a plurality of feature points that are sequentially set one by one.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to any one of claims 3 to 5,
The reference marker generation unit generates a polygonal reference marker having each of a plurality of feature points as vertices.
An ultrasonic diagnostic apparatus.

Images