JP7112713B2 - Heart rate measurement processor - Google Patents

Description

The present invention relates to a heartbeat measurement processing device for measuring heartbeats of a living body such as a fetus.

Currently, a delivery monitoring device is widely used for NST (Non Stress Test) in order to diagnose the health condition of a fetus in obstetrics. A delivery monitoring device uses a probe that transmits and receives ultrasonic waves based on the ultrasonic Doppler effect, and the distance between the fetal heart and the probe changes as the fetal heart vibrates during systole and diastole. This makes use of the property (called the Doppler effect) that the ultrasound frequency changes only slightly when the ultrasonic waves transmitted from the probe are reflected by the heart. By multiplying the transmitted ultrasonic wave and its reflected wave, the vibration of the frequency component corresponding to the envelope part of the amplitude-modulated wave used in the communication field (frequency component in the audible range, also known as "beat") ) appears. This frequency component can be output as sound by a speaker or the like. Further, it is known that the heart rate is obtained by processing using an autocorrelation function.

Usually, in the diagnosis of NST by a delivery monitor, the fetal heart rate is continuously measured while the pregnant woman is in a relaxed state for about 20 to 40 minutes. For example, in Patent Document 1, a detection processing unit that acquires a detection signal related to a heartbeat state detected by reflecting an ultrasonic signal transmitted toward the body in a contact detection sensor attached to the human body, and the acquired detection Equipped with a heart sound processing unit that processes based on signal amplitude data to obtain the period of the detected signal in real time, and a heart sound analysis unit that processes the obtained period of the detected signal by fast Fourier transform and analyzes the frequency in real time. A heart rate analyzer is described.

Since the conventional delivery monitoring device measures the heart rate based on the sound information of the reflected ultrasound, it is possible to confirm that the ultrasound transmitted from the probe is accurately reflected by the fetal heart. Although necessary, there is no means for confirming whether ultrasound waves are being reflected off the fetal heart. Therefore, if the fetus moves in the uterus during measurement and the fetal heart moves out of the irradiation range of the ultrasonic signal transmitted from the probe, or if the mother moves during measurement, the setting before measurement will be canceled. The case where the probe deviates from the position is dealt with by adjusting the probe flexibly. When the position of the fetal heart to be measured is out of the ultrasonic irradiation range, the fetal heart rate cannot be measured continuously and accurately. In addition, for example, in the case of measuring the heart rate of multiple fetuses such as twins or more, there is a risk that the fetus to be measured may be replaced with the movement of multiple fetuses, so it is necessary to continuously measure the heart rate of each fetus We are dealing with this.

On the other hand, in the medical field, examination technology using ultrasonic diagnostic imaging equipment has been widely used for a long time. It's becoming Ultrasonic image diagnostic apparatuses are also used for fetal diagnosis, and image diagnostic methods such as the color Doppler method, the pulse Doppler method, and the M-mode method have been proposed (see Patent Documents 2 to 4). In these diagnostic ultrasound imaging methods, by applying ultrasonic waves to red blood cells in the blood flowing through blood vessels, the speed of blood flow (maximum speed, average speed, etc.) is obtained by the Doppler effect, and the image is displayed in real time. It is possible to display.

By performing ultrasound image diagnosis of the fetus, the state of the fetus in the womb and the direction of blood flow (the umbilical cord of the fetus) can be displayed as images in real time. Also proposed is a function of determining the heart rate based on the velocity of blood flow in fetal blood vessels (see Non-Patent Document 1).

JP 2015-229030 A JP 2005-087634 A JP 2009-119250 A JP 2011-098191 A

Ken Murashita and three others, "Development of child fetal heart rate measurement function", September 2015, Hitachi, Ltd., MEDIX, vol. 63, p. 35-39

As described above, conventional delivery monitoring devices do not have the ability to track the fetal heart position, which fluctuates according to the movement of the fetus in the uterus, and to constantly and accurately capture the heart position. Stable heartbeat analysis becomes difficult when the fetal heart position is out of the irradiation range of ultrasound.

A method of automatically measuring the heart rate of a fetus using an ultrasound diagnostic imaging device has been proposed. It is not intended for continuous and accurate measurement over a long period of time, such as in diagnosis, and there are issues with stability and accuracy in continuously measuring the instantaneous heart rate of a fetus.

Therefore, in order to solve the problems in accurately analyzing the NST, it is necessary to focus on the part that does not move with respect to the movement of the fetus in the womb or the part that has a small movable range as the measurement target. Conceivable. For example, focusing on the umbilical artery (umbilical cord) attached to the placenta which hardly moves, a method of measuring the pulse rate equivalent to the heart rate of the fetus can be considered. Since the umbilical artery is attached to the placenta and its range of motion is limited to its neighboring region, continuous and accurate pulse rate measurement can be expected.

When measuring the umbilical artery attached to the placenta, the umbilical cord is smaller and thinner than the fetal heart. There is a problem that it is difficult to continuously irradiate the umbilical artery accurately. In addition, when irradiating the umbilical artery attached to the placenta with ultrasonic waves, if the ultrasonic waves are applied from the outside of the placenta (front side of the placenta), the ultrasonic waves will be irradiated through the placenta, and the intensity of the reflected waves will be weakened. In addition, when applied from the inside of the placenta (back side of the placenta), the movement of the fetus covers the umbilical artery, making stable measurement impossible. In addition, the position of the placenta varies from mother to mother, and it is necessary to be able to flexibly respond to such individual differences so that the measurement can be performed in a relaxed state that does not place stress on the mother.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a heart rate measurement processing apparatus capable of continuously and accurately measuring the heart rate of a living body such as a fetus.

A heartbeat measurement processing apparatus according to the present invention includes an intrauterine detection unit including a probe that emits ultrasonic waves and outputs a detection signal; a transmission/reception unit that acquires a detection signal by irradiating sound waves; an image processing unit that generates an image of the detection target area based on the detection signal and acquires position information of the detection target area; and based on the position information. a pulse signal of the root portion of the umbilical artery attached to the placenta based on the detection signal of the probe of the intrauterine detection unit arranged corresponding to the root portion of the umbilical artery attached to the placenta. A signal processing unit and a heartbeat processing unit for calculating fetal heartbeat data based on the pulse signal are provided. Further, a switching processing unit is provided for switching between pulse signal processing and image processing for the detection signal. Furthermore, the in-utero detection unit includes a plurality of probes, and the signal processing unit selects the probe that outputs the pulse signal based on the detection signal. Further, the intrauterine detection unit arranges the plurality of probes around the central probe so that the irradiation ranges of the remaining probes partially overlap or are in contact with each other. Further, the signal processing section selects the probes whose pulse rate of the pulse signal is within a predetermined range.

According to the present invention, an image is generated of the detection target area for measuring the heartbeat of the living body, the position information is acquired, and the detection unit is arranged based on the position information, so that the measurement process can be performed accurately. can. Further, by selecting a probe that outputs a pulse signal using a plurality of probes, continuous and stable measurement processing of the heart rate of the living body can be performed even when the detection target area moves.

1 is a schematic block configuration diagram relating to an embodiment of a heart rate measurement processing device according to the present invention; FIG. FIG. 4 is an explanatory diagram regarding an example of arrangement of probes in a detection unit; It is a flow regarding heart rate measurement processing. 1 shows an example of an ultrasound image of the placenta and umbilical artery. 4 is a graph showing a waveform of a pulse signal and a waveform of a heartbeat signal; 4 is a graph showing changes in the pulse rate obtained from the pulse signal and the heart rate obtained from the heart rate signal;

The present invention will be specifically described below. FIG. 1 is a schematic block diagram of an embodiment of a heartbeat measurement processing device according to the present invention. The heartbeat measurement processing apparatus includes a processing unit 10, a storage unit 11, a display unit 12, and an operation unit 13. The processing unit 10 includes a maternal detection unit 14 attached to the outside of the mother's heart, which is a pregnant woman. An intrauterine detector 15 attached near the outside of the placenta is connected.

The processing unit 10 includes a transmitting/receiving unit 100 that receives detection signals by reflecting ultrasonic signals transmitted toward the inside of the body from the maternal detection unit 14 and the intrauterine detection unit 15, and processes the detection signals by pulse signal processing or image processing. a switching processing unit 101 that processes the received detection signal to obtain a pulse signal of the umbilical artery, which is a detection target area; A heartbeat processing unit 103 for extracting a signal, a heartbeat analysis unit 104 for analyzing the heartbeat signal extracted by the heartbeat processing unit 103, a mode processing unit 105 for mode-processing the received detection signal into color Doppler mode or B mode, and mode processing. An image processing unit 106 that generates a mode image based on the mode signal processed by the unit 105 and acquires position information of the detection target area, a processing result of the heartbeat processing unit 103, and an analysis result of the heartbeat analysis unit 104 are displayed on the display unit 12. A display processing unit 107 is also provided for performing display processing on the mode image generated by the image processing unit 106 as well as performing display processing on the mode image.

The storage unit 11 includes a signal processing DB 110 that stores obtained detection signals, an image processing DB 111 that stores processing data regarding mode signals and mode images, and a heartbeat processing DB 112 that stores processing data regarding pulse signals and heartbeat signals. ing.

The processing unit 10, the storage unit 11, the display unit 12, and the operation unit 13 are integrated with a computer, a hard disk, a display, a keyboard, etc., and programs and data necessary for realizing the functions of each processing unit are provided. can realize the heart rate measurement processing device described above. In addition, a device configuration in which a device portion that realizes the functions of the signal processing portion 102, the heartbeat processing portion 103, and the heartbeat analysis portion 104 and a device portion that realizes the functions of the mode processing portion 105 and the image processing portion 106 are separated. It can also be realized with various device configurations as needed.

The maternal detection unit 14 can use a probe that is used in a known delivery monitoring device, and emits ultrasonic waves into the maternal body according to the drive signal from the transmitting/receiving unit 100, and reflects them from the heart, which is the area to be detected. The ultrasound is converted into an echo signal and output to the transmitting/receiving unit 100 .

The intrauterine detection unit 15 includes a plurality of probes, and drives each probe with a drive signal from the transmission/reception unit 100 to irradiate ultrasonic waves toward the placenta, which is a detection target area, and pulse signal processing. and outputs echo signals necessary for image processing to the transmitting/receiving unit 100 . It is preferable that the intrauterine detection unit 15 be attached so as to irradiate the placenta from the outside (front side). The umbilical artery is attached to the inside (back side) of the placenta, and when ultrasonic waves are applied from the outside, the umbilical artery is detected through the placenta. It is preferred to place 15 outside the placenta.

In the pulse signal processing, a plurality of probes are arranged so that their irradiation ranges partially overlap or touch each other. For example, FIG. 2 shows an arrangement example of five probes. Four probes P1 to P4 are arranged at equal intervals around the central probe P0, and the irradiation range R0 of the central probe P0 is defined as the irradiation range R1 to R4 of the probes P1 to P4. Set to be surrounded by Then, the intrauterine detection unit 15 is attached so that the root portion of the umbilical artery attached to the placenta is within the radiation range R0 of the central probe P0. By attaching the intrauterine detection unit 15 in this way, it is possible to stably obtain a pulse signal from the root portion of the umbilical artery, which has a small movable range. In addition, since the umbilical artery moves around the base of the placenta due to the movement of the fetus, even if the root part is out of the irradiation range R0 of the central probe P0, the surrounding probes P1 to P4 The root portion of the umbilical artery comes to fall within any irradiation range, making it possible to continuously obtain a pulse signal. In this case, the number of probes may be arranged in a number other than five. For example, by using nine probes, eight probes are arranged around the center probe. should be spaced apart.

In the image processing, the entire placenta is scanned and a two-dimensional image of the placenta is generated by performing scanning control while irradiating ultrasonic waves from one probe toward the placenta according to the driving signal from the transmitting/receiving unit 100. An echo signal can be obtained. In the intrauterine detection unit 15, the probe for pulse signal processing may also be used for image processing. It can also be configured as

The transmitting/receiving unit 100 transmits a driving signal to the maternal detection unit 14 and the intrauterine detection unit 15 to irradiate the inside of the body with ultrasonic waves. receive echo signals obtained from The intrauterine detection unit 15 is controlled to scan the irradiation range of the ultrasonic wave along a predetermined detection line.

The switching processing unit 101 performs processing for switching the detection signal transmitted from the transmitting/receiving unit 100 to pulse signal processing or image processing. Specifically, processing is performed to switch to an image processing phase in which image processing is performed to acquire position information of the umbilical cord artery or to a pulse signal processing phase in which a pulse signal is obtained based on a detection signal from the probe. Then, along with the process of switching from the image processing phase to the pulse signal processing phase, the process of switching to the image processing phase is performed when the probe for obtaining the pulse signal cannot be selected in the pulse signal processing phase.

By performing such a switching process, even if the umbilical artery moves and pulse signals cannot be obtained from multiple probes, the phase is automatically switched to the image processing phase, and the position of the probe is adjusted. Processing can be performed to return to the signal processing phase, and processing can be performed so that the pulse signal can be continuously obtained. Therefore, it is possible to continuously analyze the heart rate based on the obtained pulse signal, and support information for accurately grasping the health condition of the fetus at all times, predicting abnormal conditions that may occur in the future, and taking preventive measures. can be provided.

Further, the switching processing unit 101 has a function of executing a special mode for coping with emergency situations in addition to the normal mode for performing the above-described measurement processing, and switches between the normal mode and the special mode as necessary. perform processing to switch between The processing performed in the special mode includes, for example, processing to accept interrupt signals from each part of hardware and software, processing to determine whether to enable or disable the current interrupt according to the requested interrupt level, and processing to re-interrupt. Processing to prohibit interrupt processing, processing to execute a special routine prepared according to the content of the interrupt processing, processing to notify the sender that the specified interrupt processing has ended, processing to cancel the interrupt prohibition processing, etc. be done.

The signal processing unit 102 processes the output signals of the maternal detection unit 14 and the intrauterine detection unit 15 obtained from the transmission/reception unit 100, and outputs a maternal heartbeat signal and an umbilical artery pulse signal. The obtained heartbeat signal and pulse signal are stored in the signal processing DB 110 of the storage unit 11 .

For the output signals of a plurality of probes output from the intrauterine detection unit 15, pulse analysis is sequentially performed on the output signals of each probe using an autocorrelation function, and the obtained pulse rate is the heart rate of the fetus. The presence or absence of a pulse signal is determined based on whether or not it is within the range of standard values (120 to 160 rpm). It is preferable that the heart rate range, which is used as a criterion for determination, can be individually set because there are individual differences. When the output signal includes a pulse signal, a Doppler sound (beating sound) becomes audible. You can also select tentacles. When a pulse signal is not obtained from any of the probes of the intrauterine detection unit 15, the switching processing unit 101 is instructed to perform image processing, and warning processing is performed to adjust the positions of the probes.

The heartbeat processing unit 103 samples the pulse signal obtained in the signal processing unit 102 at predetermined time intervals, and uses the average amplitude difference function (AMDF) method based on the amplitude data of the pulse signal obtained by sampling. The period of the pulse signal is obtained by signal correlation, and heartbeat data such as RR time is calculated. The heartbeat signal obtained from the mother's body detector 14 is also subjected to similar processing to obtain heartbeat data. The calculated heartbeat data is stored in the heartbeat processing DB 112 of the storage unit 11 .

The heartbeat analysis unit 104 performs frequency analysis processing using a fast Fourier transform (FFT) for each predetermined interval based on the heartbeat data obtained by the heartbeat processing unit 103, thereby analyzing changes in the heartbeat state from the viewpoint of frequency characteristics. Analyze in real time. For example, as described in Patent Document 4, it is known that when there is a peak in the low frequency component (LF), it is in a stress state, and when there is a peak in the high frequency component (HF), it is in a resting state. Based on the analysis results, it can be expected to be used as support information for diagnosing the health condition of the fetus in real time. The obtained analysis result is stored in the heartbeat processing DB 112 of the storage unit 11 .

Stable and accurate heartbeat data over a long period of time is required to diagnose the health condition of the fetus by performing minute fluctuation analysis of the instantaneous heartbeat rate of the fetus (corresponding to the RR time interval RI) based on the heartbeat data. However, as described above, this apparatus can stably obtain continuous heartbeat data.

The mode processing unit 105 performs B-mode processing corresponding to B-mode scanning and color Doppler mode processing corresponding to color Doppler mode scanning based on the detection signal obtained from the transmitting/receiving unit 100 . Selection of the mode is appropriately performed by a selection operation on the operation unit 13 . Such mode processing can be performed by a known processing method. In the B-mode processing, the detection signal is envelope-detected and logarithmically compressed to obtain a B-mode signal representing the intensity of the detection signal in luminance. In color Doppler mode processing, detection signals are orthogonally detected, flow velocity information such as average flow velocity of blood or the like in the scanning region is calculated by frequency analysis, and color Doppler mode signals corresponding to the flow velocity information are obtained. The obtained mode signal is stored in the image processing DB 111 of the storage unit 11 .

The image processing section 106 generates a mode image based on the mode signal processed by the mode processing section 105 . A two-dimensional image corresponding to the scanning area is generated based on the mode signal, and a three-dimensional image is generated by combining the generated two-dimensional images. Such image processing can be performed by a known processing method. The generated image allows real-time display of the umbilical artery attached to the placenta.

The image processing unit 106 performs processing for specifying the position of the umbilical artery, which is the detection target area, based on the placenta image displayed in real time. By designating the image area corresponding to the root portion of the umbilical artery, which is the detection target area, using the operation unit 13, the position information (coordinate position, angular position) is acquired with reference to the origin position of the image space. The image processing unit 106 can also perform processing to automatically identify the umbilical artery based on the image of the placenta using artificial intelligence and acquire position information.

The display processing unit 107 performs display processing on the mode image generated by the image processing unit 106 so that the detection target area can be specified. In addition, the processing result of the heartbeat processing unit 103 and the analysis result of the heartbeat analysis unit 104 are displayed on the display unit 12, the heartbeat state of the fetus can be confirmed in real time, and the health condition of the fetus can be diagnosed.

FIG. 3 is a flow regarding heart rate measurement processing. First, the maternal body detection unit 14 and the intrauterine detection unit 15 are set (S100). The maternal detection unit 14 is attached at a position facing the heart of the pregnant woman, and the intrauterine detection unit 15 is attached at a position facing the outside (front side) of the placenta. Next, the phase is switched to the image processing phase (S101), the intrauterine detection unit 15 is driven to scan while irradiating ultrasonic waves toward the placenta, and a mode signal is generated based on the obtained detection signal (S102). . An ultrasound image of the placenta is generated from the generated mode signals (S103). FIG. 4 shows an example of an ultrasound image of the placenta and umbilical artery. In the center of the screen, the umbilical artery narrowly extending toward the right side is clearly displayed.

Positional information about the root portion of the umbilical artery in the generated image is acquired (S104) and stored in the storage unit 11. FIG. The position information may be selected by touching the corresponding portion of the image displayed on the screen, or may be input from the operation unit and saved. Positional information can also be obtained by learning placental images using artificial intelligence and automatically specifying an image region corresponding to the umbilical artery.

Next, the phase is switched to the pulse signal processing phase (S105), and the intrauterine detector 15 is set at a position facing the umbilical artery using the acquired position information (S106). In the arrangement example of the probes shown in FIG. 2, the root portion of the umbilical artery may be set so as to coincide with the center of the irradiation range of the central probe P0.

The intrauterine detection unit 15 is attached to an attachment such as a waist belt, and the attachment is attached around the abdomen of the pregnant woman, so that the attachment position can be adjusted. It becomes possible to When adjusting the mounting position, a marking tool or the like is used to display a mark on the abdomen based on the position information, and the adjustment can be made according to the displayed mark. In addition, the position can be automatically adjusted by providing a moving means in the fetal detecting section 15 . For example, a movable carriage may be attached to a mounting table that surrounds the abdomen in a ring shape, and the intrauterine detector 15 may be placed on the carriage and moved in accordance with position information.

Next, the plurality of probes of the intrauterine detection unit 15 are sequentially driven to acquire detection signals, and processing is performed to acquire pulse signals, and the pulse rate of the acquired pulse signals is within a predetermined range (for example, 120 to 120). 160 rpm) probe is selected (S107). In the arrangement example of the probes shown in FIG. 2, the pulse rate can be calculated by selecting P1→P2→P3→P4 in order from the probe P0.

It is checked whether or not there is a selected probe (S108), and if there is no selected probe (S108: NO), interrupt processing is performed (S113), the process returns to step S101, and the image processing phase switch to Then, image processing is performed again to acquire the position information of the umbilical artery. If there is a selected probe (S108: YES), heartbeat processing is performed on the acquired pulse signal to calculate heartbeat data such as heartbeat cycle and RR time (S109). Analysis processing is performed based on the obtained heartbeat data (S110), the heartbeat state of the fetus is analyzed, and the analysis result is displayed on the screen (S111).

Next, it is determined whether the pulse rate obtained based on the detection signal of the selected probe is within a predetermined range (S112), and if the pulse rate is within the predetermined range (S112: YES) returns to step S109, acquires the pulse signal, and performs heartbeat processing and analysis processing. If the pulse rate is not within the predetermined range (S112: NO), the process returns to step S107, the probe selection process is performed, and the probe whose pulse rate is within the predetermined range is selected again.

An experiment was conducted to compare the processing result of the pulse signal obtained by the processing described above and the processing result of the heartbeat signal obtained at the same time. FIG. 5 shows a pulse signal waveform (FIG. 5(a)) and a heartbeat signal waveform (FIG. 5(b)), where the horizontal axis represents time and the vertical axis represents amplitude. It can be seen that the pulse signal also has peaks corresponding to the peaks of the heartbeat signal.

FIG. 6 is a graph showing changes in the pulse rate obtained from the pulse signal and the heart rate obtained from the heartbeat signal, where the horizontal axis represents time and the vertical axis represents the average heart rate. A dark-colored graph indicates the temporal transition of the pulse rate, and a light-colored graph indicates the temporal transition of the heart rate. Both heart rate and their transition are almost the same, and it can be seen that the pulse signal accurately reflects the heartbeat signal.

As described above, since the position of the root portion of the umbilical artery, which is the detection target region, is specified and measured based on the ultrasonic image, the pulse signal can be reliably acquired. Further, since the pulse signal is measured after the signal processing of the image processing, it can be accurately performed without interfering with the irradiation of ultrasonic waves during the image processing. Furthermore, since measurements are performed using multiple probes, even if the umbilical artery moves, it is possible to select the probe that detects the pulse signal and perform stable signal processing continuously. Become. In particular, when diagnosing the health condition of a fetus, it is necessary to continuously measure the heartbeat condition of the pregnant woman in a relaxed state over a long period of time. can.

In the above example, the pulse signal is acquired with the root portion of the umbilical artery attached to the placenta as the detection target region, but depending on the condition of the mother's body, a blood vessel portion other than the umbilical artery may also be the detection target region. It is possible to deal with various living organisms.

REFERENCE SIGNS LIST 1 Heart rate measurement processing device 10 Processing unit 11 Storage unit 12 Display unit 13 Operation unit 14 Maternal detection unit 15 Womb Detection unit 100 Transceiver unit 101 Switching processing unit 102 Signal processing unit 103 Heartbeat processing unit 104 Heartbeat analysis unit 105 Mode processing unit 106... Image processing unit, 107... Display processing unit

Claims (5)

An intrauterine detection unit equipped with a probe that emits an ultrasonic wave and outputs a detection signal, and an intrauterine detection unit is driven to irradiate an ultrasonic wave toward the placenta, which is a detection target area, and acquire a detection signal. a transmitting/receiving unit, an image processing unit that generates an image of the detection target area based on the detection signal and acquires position information of the detection target area, and a root of the umbilical artery attached to the placenta based on the position information. a signal processing unit that acquires a pulse signal from the root portion of the umbilical artery attached to the placenta based on the detection signal from the probe of the intrauterine detection unit arranged corresponding to the portion; and a heartbeat processing unit for calculating fetal heartbeat data. 2. The heart rate measurement processing device according to claim 1, further comprising a switching processing unit for switching between pulse signal processing and image processing of the detection signal. 3. The intrauterine detection unit according to claim 1 or 2, wherein the in utero detection unit includes a plurality of the probes, and the signal processing unit selects the probe that outputs the pulse signal based on the detection signal. Heart rate measurement processing device. 4. The heartbeat according to claim 3, wherein the intrauterine detection unit arranges a plurality of the probes around the central probe so that the irradiation ranges of the remaining probes partially overlap or are in contact with each other. Measurement processing equipment. 5. The heartbeat measurement processing device according to claim 3, wherein the signal processing unit selects the probe whose pulse rate of the pulse signal is within a predetermined range.

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