WO2013057999A1 - 超音波撮像装置及び方法 - Google Patents
超音波撮像装置及び方法 Download PDFInfo
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/52—Devices using data or image processing specially adapted for diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/5215—Devices using data or image processing specially adapted for diagnosis using ultrasonic, sonic or infrasonic waves involving processing of medical diagnostic data
- A61B8/5223—Devices using data or image processing specially adapted for diagnosis using ultrasonic, sonic or infrasonic waves involving processing of medical diagnostic data for extracting a diagnostic or physiological parameter from medical diagnostic data
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/06—Measuring blood flow
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/48—Diagnostic techniques
- A61B8/488—Diagnostic techniques involving Doppler signals
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/52—Devices using data or image processing specially adapted for diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/5207—Devices using data or image processing specially adapted for diagnosis using ultrasonic, sonic or infrasonic waves involving processing of raw data to produce diagnostic data, e.g. for generating an image
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- G—PHYSICS
- G16—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
- G16H—HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA
- G16H50/00—ICT specially adapted for medical diagnosis, medical simulation or medical data mining; ICT specially adapted for detecting, monitoring or modelling epidemics or pandemics
- G16H50/30—ICT specially adapted for medical diagnosis, medical simulation or medical data mining; ICT specially adapted for detecting, monitoring or modelling epidemics or pandemics for calculating health indices; for individual health risk assessment
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/04—Measuring blood pressure
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/06—Measuring blood flow
- A61B8/065—Measuring blood flow to determine blood output from the heart
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/08—Detecting organic movements or changes, e.g. tumours, cysts, swellings
- A61B8/0883—Detecting organic movements or changes, e.g. tumours, cysts, swellings for diagnosis of the heart
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/08—Detecting organic movements or changes, e.g. tumours, cysts, swellings
- A61B8/0891—Detecting organic movements or changes, e.g. tumours, cysts, swellings for diagnosis of blood vessels
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/13—Tomography
- A61B8/14—Echo-tomography
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/46—Ultrasonic, sonic or infrasonic diagnostic devices with special arrangements for interfacing with the operator or the patient
- A61B8/461—Displaying means of special interest
- A61B8/463—Displaying means of special interest characterised by displaying multiple images or images and diagnostic data on one display
Definitions
- the present invention relates to a medical ultrasonic imaging apparatus and method, and more particularly to an ultrasonic imaging apparatus that accurately measures a blood flow velocity desired by an examiner.
- Doppler measurement method using the Doppler effect as a method for obtaining blood flow velocity using ultrasonic waves.
- the Doppler measurement method blood flow velocities in all regions irradiated with ultrasonic waves are detected, and thus the obtained velocity information (blood flow velocity distribution and blood flow velocity) has a width. Therefore, it is necessary to extract speed information considered appropriate by the examiner from the obtained distribution, but ambiguity remains in speed extraction. This ambiguity leads to diagnostic ambiguity.
- Patent Documents 1 and 2 disclose a technique for preventing an error caused by noise or signal folding from entering a trace line of a Doppler waveform when determining a speed based on the Doppler waveform.
- Patent Document 3 discloses a technique for auto-tracing as a trace level a plurality of luminance levels that are lower than a maximum luminance level by a predetermined amount as a reference for Doppler waveform tracing.
- an object of the present invention is to eliminate the ambiguity of the velocity distribution information obtained by Doppler measurement and accurately determine the flow velocity value desired by the examiner.
- the ultrasonic imaging apparatus of the present invention that solves the above problems estimates a model describing a physical phenomenon including velocity for a blood flow that is a target of velocity information desired by the examiner, and measures the velocity of the measured measurement region. Velocity information that matches the estimated blood flow model is determined from the distribution information.
- the ultrasonic imaging apparatus of the present invention includes an ultrasonic probe that transmits ultrasonic waves to an inspection target and receives an echo signal reflected from the inspection target, and an echo signal received by the ultrasonic probe.
- a speed determination unit that determines speed information from the speed distribution acquired by the speed distribution acquisition unit, the speed determination unit sets a model of the speed information, and the model and the speed distribution acquisition unit The speed information is determined so that the acquired speed distribution matches.
- the velocity determination unit estimates a spatial distribution of the velocity of the fluid as the model, and the velocity distribution obtained by the velocity distribution acquisition unit acquires the spatial distribution of the estimated velocity.
- the speed information is calculated from the spatial distribution of the determined speed.
- the velocity determination unit sets a model represented by the sum of a step function and a delta function as a model of fluid velocity information, and uses the value of the singular point of the velocity distribution acquired by the velocity distribution acquisition unit. The speed information is calculated.
- the ultrasonic imaging method of the present invention is an ultrasonic imaging method for acquiring diagnostic information of the inspection object using an echo signal reflected from the inspection object irradiated with ultrasonic waves, and using the echo signal, Obtaining a velocity distribution of a fluid included in a test object; and determining velocity information from the velocity distribution of the fluid, wherein the velocity information determining step sets a model of the velocity information; and Searching and determining a velocity matching the model from the velocity distribution of the fluid, and displaying the determined velocity and / or diagnostic information calculated from the velocity.
- the diagnostic information calculated from the velocity includes, for example, any of pressure difference, absolute pressure, time differential value of pressure, time constant, and pressure-volume relationship diagram.
- the accuracy of Doppler measurement is improved, and the accompanying calculation accuracy related to pressure, which has been poor in accuracy, is improved.
- FIG. 1 is a block diagram illustrating a device configuration of an ultrasonic imaging apparatus according to an embodiment of the present invention, where FIG. The flowchart which shows operation
- (A) And (b) is a figure explaining an imaging region, respectively. It is a figure explaining the concept of speed measurement, (a) shows the case where the speed in an area
- An ultrasonic imaging apparatus of the present invention transmits an ultrasonic wave to an inspection object and receives an echo signal reflected from the inspection object, and a signal for processing an echo signal received by the ultrasonic probe
- a processing unit and a display unit for displaying a processing result by the signal processing unit are provided.
- the signal processing unit includes a velocity distribution acquisition unit that acquires the velocity distribution of the fluid included in the inspection target from the echo signal, and a velocity determination unit that determines velocity information from the velocity distribution acquired by the velocity distribution acquisition unit.
- the speed determination unit sets a model of speed information, and determines the speed information so that the model and the speed distribution acquired by the speed distribution acquisition unit match.
- the velocity determination unit estimates the spatial distribution of the velocity of the fluid as a model, and determines and determines the estimated spatial distribution of the velocity so as to match the velocity distribution acquired by the velocity distribution acquisition unit.
- the velocity information is calculated from the spatial distribution of the velocity.
- the velocity determination unit sets a model represented by the sum of a step function and a delta function as a model of fluid velocity information, and uses the value of the singular point of the velocity distribution acquired by the fluid velocity distribution acquisition unit, Calculate speed information.
- FIG. 1 is a block diagram illustrating an apparatus configuration example of an ultrasonic imaging apparatus according to the present invention.
- FIG. 1A is a diagram illustrating the entire apparatus, and
- FIG. 1B is a diagnostic information calculation unit that is part of a signal processing unit.
- FIG. 1A the ultrasonic imaging apparatus according to the present embodiment includes an apparatus main body 1 and an ultrasonic probe 2.
- the apparatus main body 1 is used to generate an ultrasonic image while controlling the ultrasonic probe 2, and includes an input unit 10, a control unit 11, an ultrasonic signal generator 12, an ultrasonic receiving circuit 13, and a display unit. 14 and a signal processing unit 15.
- the ultrasonic probe 2 is in contact with the living body (subject) 3 and irradiates the irradiation region 30 with ultrasonic waves according to the signal generated by the ultrasonic signal generator 12 and also reflects the reflected wave echo signal of the irradiation region 30. Receive.
- the ultrasonic probe 2 generates a continuous wave or a pulse wave according to the scanning method.
- the input unit 10 includes a keyboard and a pointing device for setting an operation condition of the ultrasonic imaging apparatus to the control unit 11 by an examiner who operates the ultrasonic imaging apparatus, and also uses an electrocardiogram as an electrocardiogram signal input unit. Function.
- the control unit 11 controls the ultrasonic signal generator 12, the ultrasonic reception circuit 13, the display unit 14, and the signal processing unit 15 based on the operating conditions of the ultrasonic imaging apparatus set by the input unit 10, for example, a computer CPU of the system.
- the ultrasonic signal generator 12 includes an oscillator that generates a signal having a predetermined frequency, and sends a drive signal to the ultrasonic probe 2.
- the ultrasonic receiving circuit 13 performs signal processing such as amplification and phasing on the reflected echo signal received by the ultrasonic probe 2.
- the ultrasonic receiving circuit 13 includes a receiving circuit, envelope detection means, and means for performing Log compression.
- the display unit 14 outputs information obtained by the signal processing unit 15.
- the signal processing unit 15 has a function of generating an ultrasound image from the reflected echo signal from the ultrasound probe 2. Details thereof will be described later.
- the apparatus main body 1 includes a scan converter and an A / D converter.
- the scan converter may be included in the ultrasonic receiving circuit 13 or may be provided in the subsequent stage of the signal processing unit 15.
- the ultrasonic receiving circuit 13 includes a scan converter, there is an advantage that the amount of data handled by the signal processing unit 15 is reduced.
- the scan converter is not included in the ultrasonic receiving circuit 13, a large amount of data can be handled by the signal processing unit 15, and a highly accurate measuring device can be realized.
- the A / D converter is provided before the signal processing unit 15.
- the sampling frequency is usually between 20 MHz and 50 MHz.
- the signal processing unit 15 includes a shape extraction unit 151, a flow velocity distribution acquisition unit 152, a diagnostic information calculation unit 153 that calculates velocity information, a memory 154, and an addition unit 155 as main elements related to the present invention.
- the diagnostic information calculation unit 153 includes a speed determination unit 156 that performs speed determination, an accuracy calculation unit 157 that calculates the accuracy of the processing result of the diagnosis information calculation unit 153, and the speed.
- Calculation units 158 to 160 for calculating various kinds of diagnostic information such as pressure range, absolute pressure, pressure-volume curve and the like are provided.
- the shape extraction unit 151 uses, for example, a B-mode image, that is, a two-dimensional tissue shape image or a three-dimensional imaging method using a planar imaging method of an ultrasonic irradiation target, from the reflected echo signal output from the ultrasound receiving circuit 13. Is used to form a three-dimensional tissue shape image.
- the shape extraction unit 151 extracts tissue position information from the tissue shape image.
- the flow velocity distribution acquisition unit 152 extracts blood flow information at a predetermined position obtained from the tissue shape information.
- the speed determination unit 156 determines speed information desired by the examiner from the blood flow information.
- the memory 154 stores reflected echo signals and information held by the shape extraction unit 151, the flow velocity distribution acquisition unit 152, and the diagnostic information calculation unit 153.
- the ultrasonic imaging apparatus of the present embodiment includes a cycle information acquisition unit (input unit 10) that acquires cardiac cycle information (electrocardiogram and electrocardiogram) to be examined, and the velocity distribution acquisition unit 152 includes a cycle information acquisition unit. Based on the acquired cardiac cycle information, a velocity distribution is acquired for each cardiac cycle.
- the adding unit 155 adds the velocity distribution acquired by the velocity distribution acquiring unit 152 for each cardiac cycle.
- the speed determination unit 156 can determine speed information using the added speed distribution.
- the accuracy calculation unit 157 calculates the accuracy of the speed information calculated by the speed determination unit 156 and / or the diagnostic information calculated from the speed information. For example, the accuracy calculation unit 157 calculates the accuracy (index) using the difference between the maximum value and the minimum value of the velocity distribution acquired by the velocity distribution acquisition unit.
- the pressure difference calculation unit 158 calculates the pressure difference inside and outside the valve using the speed information of the valve backflow determined by the speed determination unit 156.
- the absolute pressure calculation unit 159 calculates an absolute pressure from the pressure range calculated by the pressure range calculation unit 158 and a reference pressure set in advance or externally input.
- the volume calculation unit 160 calculates the volume of a desired organ such as the left ventricle at a plurality of times from the shape image formed by the shape image forming unit 151. Further, the signal processing unit 15 uses the exponential function to approximate the temporal differential value (dP / dt) and / or the relaxation state of the left ventricle from the absolute pressure of the left ventricle calculated by the absolute pressure calculation unit 159. A means for calculating the constant ⁇ may be provided.
- the speed information is the speed information of the heart valve regurgitation
- the speed determination unit uses a jet model as a model of the speed information.
- the velocity determining unit creates the jet model by convolution of the model of the jet development area and the model of the jet undeveloped area.
- FIG. 2 The processing flow of this embodiment is shown in FIG. In FIG. 2, as a specific example, a case where a region including the aortic valve and the left ventricle is set as the irradiation region 30 in FIG. 1 will be described. Good.
- Step S1> imaging is performed to obtain form information (B-mode image) of the irradiation area.
- the ultrasonic frequency of the B-mode image is in the range of 1 MHz to 20 MHz that can be imaged.
- the frame rate when imaging tissue that varies depending on the heartbeat is set to 20 Hz or more, which is a range in which the motion of the heart can be captured.
- the shape extraction unit 151 uses, for example, a B-mode image, that is, a two-dimensional ultrasonic biological image or a three-dimensional imaging method using a planar imaging method of an ultrasonic irradiation target, from the reflected echo output from the ultrasonic receiving circuit 13. Is used to form a three-dimensional ultrasonic biological image.
- ultrasonic biometric image data is acquired in time series.
- FIG. 3 shows the left ventricle 31, left atrium 32, right ventricle 33, mitral valve 34, left ventricular posterior wall 35, apex 36, and aortic valve 37 imaged in the two-dimensional B mode.
- tissue position information is acquired from the ultrasonic biological image formed in step S1.
- the tissue position may be determined by detecting the tissue inner wall by image processing, or the examiner may acquire the position information by specifying the tissue inner wall via the input unit 10.
- the tissue is recognized as a high luminance value, so that the high luminance value portion is a heart tissue, and a two-dimensional or three-dimensional heart tissue position is acquired.
- the position may be given by the examiner specifying the tissue inner wall that is the interface between blood and tissue via a pointing device provided in the input unit 10.
- the flow velocity distribution acquisition unit 152 pays attention to the blood flow portion in the ultrasonic biological image acquired by the shape extraction unit 151, and velocity distribution information (all or a part of the ultrasonic irradiation unit) of the blood flow portion ( Get the Doppler waveform.
- the blood flow part may be any part where blood vessels flow, and is selected according to the purpose of diagnosis.
- the blood flow flowing from the pulmonary vein to the left atrium, the blood flow flowing from the left atrium to the left ventricle, or the back flow in the mitral valve the drive from the left ventricle to the aorta Outflow and aortic valve regurgitation are also possible.
- the aortic valve regurgitation in which blood flow information is remarkable is selected as the blood flow part.
- the position of the blood flow part can be detected by image processing based on the tissue image obtained in step S2, and the desired blood flow site is set.
- the measurement target site is measured by the continuous Doppler method or the pulse Doppler method.
- the continuous Doppler method can be used for measurement.
- the continuous Doppler method with a wide speed range is used.
- the measurement region 41 of the continuous wave Doppler method is the entire beam, and the measurement region 42 of the pulse Doppler method shown in FIG. 4B is a smaller region.
- the blood flow flowing in the measurement regions 41 and 42 is not uniform and has various flow velocities, so that the ultrasonic wave irradiated by the ultrasonic probe 2 is an ultrasonic wave according to the blood flow velocity.
- the frequency of the ultrasonic wave detected by the ultrasonic probe 2 changes and various modulations are mixed according to the blood flow velocity in the measurement region.
- the flow velocity distribution acquisition unit 152 calculates the blood flow velocity based on the change amount of the ultrasonic frequency detected by the ultrasonic probe 2. An outline of blood flow velocity calculation is shown in FIG. FIG. 5A shows a case where blood flow flows in the measurement region 41 at a uniform speed.
- the velocity can be obtained by performing frequency analysis such as Fourier transform on the modulation signal 50 received by the ultrasonic probe 2.
- FIG. 5B shows a case where blood flows of various velocities exist in the measurement region 41, and the modulation signal 50 received by the ultrasonic probe 2 is a modulation signal 51 that reflects individual blood scatterer velocities.
- the sum of When frequency analysis is performed on the modulation signal 50, a velocity distribution 53 representing the relationship between velocity and signal intensity is acquired.
- the signal intensity corresponds to the amount of scatterers having the same velocity.
- FIG. 6A shows a valve regurgitant waveform (Doppler waveform) acquired by continuous wave Doppler, which is an experimental result acquired when the aortic valve of an edible pig is actually driven by a motor to perform opening and closing.
- the vertical axis represents the valve reverse flow speed, and the horizontal axis represents the time phase.
- FIG. 6B is a diagram showing a graph (luminance value velocity distribution) 62 showing the relationship between the velocity and luminance value of the Doppler waveform 61 at a predetermined time T.
- the vertical axis corresponds to the luminance value and the horizontal axis corresponds to the velocity. is doing.
- This graph 62 corresponds to the actual data of the signal intensity distribution 53 of the speed shown in FIG.
- FIG. 6C shows an ultrasonic irradiation region 41 for the valve flow of the aortic valve 37.
- the flow velocity distribution acquisition unit 152 preferably performs average addition of Doppler waveforms when acquiring the velocity distribution information. Thereby, the accuracy can be improved.
- the timing of the electrocardiogram or the electrocardiogram may be input from the input unit 10, or cross correlation may be performed on the Doppler waveform by image processing.
- Various physical quantities as shown in FIG. 7 can be used to detect the cardiac phase.
- FIG. 7 shows changes in the ECG signal waveform 71, the mitral valve inflow velocity waveform 72, the pulmonary valve regurgitation waveform 73, the heart wall velocity waveform 74, and the heart wall motion waveform 75 in order from the top.
- the heartbeat time phase based on the electrocardiogram signal waveform 71 captured from the input unit 10 can be recognized.
- the other waveforms 72 to 75 can be obtained from Doppler measurement or M-mode images measured over time, and can be specified by using the maximum value, minimum value, maximum value, minimum value, slope, zero cross, etc. of the waveform.
- the time phase 76 can be detected.
- Step S5 Based on the tissue position information acquired by the shape extraction unit 151 in step S2 and the velocity distribution information acquired by the flow velocity distribution acquisition unit 152 in step S3, the velocity determination unit 156 physically calculates the blood flow velocity desired by the examiner. It is determined in consideration of the consistency (S5).
- the relationship between the luminance value and the velocity distribution shown in FIG. 6B indicates how much blood having a certain velocity exists in the measurement region.
- the volume of the flow velocity having a certain velocity u is estimated from the velocity space distribution, and the relationship between the velocity u and its volume V (u) and the velocity volume relationship are estimated.
- the luminance value velocity relationship is estimated from the velocity volume relationship.
- the actually measured luminance value speed relationship is matched with the estimated luminance value speed relationship to actually obtain the desired speed U.
- Step S5 Details of step S5 will be described below with reference to the flow shown in FIG. ⁇ Step S501 >> First, for the target blood flow, the volume of the flow velocity having a certain velocity u is estimated from the model of the spatial distribution of velocity, and the relationship between the velocity u and its volume V (u) is estimated.
- the aortic regurgitation is regarded as a jet and the velocity distribution is predicted.
- the velocity distribution of the aortic valve jet is such that the velocity of the central portion (core) protrudes in the vicinity of the aortic valve 37 and there is a discontinuous change at the boundary with the periphery.
- the periphery of the core is smooth and continuously connected to the periphery.
- the area where the core area (flat part) is smooth is called the area where the jet has developed.
- the area where the core is developed and the area where the core has not been developed are divided, and different model formulas are established and integrated.
- the development region of the jet can be expressed by, for example, the following equation (1) known as the Goletler equation (Non-patent Document 1).
- u is the velocity
- K is a constant depending on the type of jet related to the momentum of the jet
- ⁇ is a function of K
- x is the distance from the jet virtual origin to the jet direction
- y is the distance from the jet center to the jet vertical direction.
- any one of an exponential function, a step function, an error function, a delta function, or a combination thereof may be used.
- R is a radius of the core region
- CR is an index indicating the width of the core region
- C is a constant between 10 and 15.
- D is a constant automatically derived by calculation and takes a value from 40 to 70.
- Step S502 Based on the relational expression between the speed and the volume calculated in step S501, the relation between the speed and the luminance value is obtained.
- This calculation can be realized by taking the logarithm of the volume of the expression (3) and adjusting the gamma function or the like.
- FIG. 10A shows a velocity distribution (relationship between velocity and luminance value) reproduced using Equation (3). This result can be said to be a good reproduction as compared with the dotted line portion of the actually measured value (luminance value speed distribution) 62 shown again in FIG.
- A, n, R, ⁇ , and U are unknowns, and are calculated by fitting from the actual measurement values in the next step.
- Step S503 Fitting the equation (Equation (3)) of the velocity distribution obtained in Step S502 and the actual measurement value 62 (FIG. 6 (b)), the unknown number of Equation (3) is obtained, and U which is the desired velocity is calculated.
- the fitting method a known method such as a least square method, a difference absolute value minimum method, or pattern matching by cross-correlation can be used.
- the fitting may be performed after the convolution integration is performed on the expression (3). In the case of the fitting not considering the convolution integration effect, the convolution effect may be corrected by the expression (5).
- Step S504 In general, when generating a Doppler waveform, no matter how uniform the velocity distribution is measured, it has a width depending on the device, such as velocity distribution 53 shown in FIG. In this step, the width of the velocity distribution depending on the apparatus is corrected. Specifically, for example, when the width characteristic function G is a Gaussian distribution shown in Expression (4) and the variance value is S, the corrected speed can be expressed by Expression (5). In the equation, Uc is the speed after correction.
- step S504 is not essential in the present embodiment, but the accuracy of speed determination can be increased by the process of step S504.
- Steps S501 to S504 described above are steps processed by the speed determination unit 156. By these steps, a desired speed U (Uc after correction) is determined.
- the diagnostic information calculation unit 153 can perform the following steps S6 to S9 (FIG. 2) using the speed U calculated by the speed determination unit 156 as described above, and calculate diagnostic information other than the speed. These steps may be selected and performed by the examiner as necessary.
- Step S6> Based on the calculated central velocity U of the aortic valve regurgitation, the pressure difference dP is obtained from the simplified Bernoulli equation shown in equation (6) (processing of the pressure difference calculating unit 158). By obtaining the pressure difference for each time phase, it is possible to obtain information on the change over time.
- the absolute pressure is further calculated based on the reference pressure (processing of the absolute pressure calculating unit 159).
- the reference pressure may be converted into the left ventricular absolute pressure P LV based on the reference pressure P input from the input unit 10.
- the aorta may be selected as the reference point for the reference pressure
- the aortic pressure PAO may be selected as the reference pressure.
- the aortic pressure P AO can be a value obtained in aortic blood pressure monitor
- an absolute pressure P LV left ventricle is expressed by the following equation (7).
- the volume calculation unit 160 calculates the volume of the left ventricle at a plurality of times from the shape image formed by the shape image forming unit 151.
- the left ventricular volume it is possible to use the Pombo method, the Teiholz method, or the like obtained from the inner diameter of the left ventricle obtained from a two-dimensional captured image assuming that the left ventricle is a spheroid. Or it is also possible to measure directly by imaging the shape of the heart three-dimensionally.
- a pressure-volume relationship diagram representing the relationship between the calculated left ventricular volume V at a plurality of times and the absolute pressure P at the plurality of times calculated in step S5 is created. An example of the pressure-volume relationship diagram is shown in FIG.
- the curve of a plurality of looped, pressure, measured at different physical conditions for the test object - is the volume relationship curve C PV, shows one of the loop in one heartbeat.
- the different physical conditions include, for example, before and after applying a load to the lower limbs and before and after administration of a drug.
- the pressure-volume relationship slope E max at the end of systole and the end-diastolic pressure-volume relationship curve C PV ED indicating the relationship between end-diastolic pressure and volume may be displayed. Good.
- the end diastolic pressure P LV ED can be calculated by the following equation (8).
- PAO is the aortic pressure when the aortic valve is opened from the end diastole. Aortic valve open o'clock from end diastole, because the change in aortic pressure is small, P AO may take any value or average value of the aortic pressure during aortic valve opening from end-diastole.
- DP Op is the pressure difference between the left ventricle and the left atrium when the aortic valve is opened.
- Step S8> The diagnostic information calculation unit 153 calculates dP / dt, which is a physical quantity indicating a temporal differential value, and / or a time constant ⁇ when the relaxation state of the left ventricle is approximated by an exponential function from the absolute pressure calculated in step S6. You can also The value obtained in steps S6 to S8 is an important diagnostic index indicating the state of the heart to be examined.
- the accuracy calculation unit 157 may calculate the accuracy of the diagnostic information calculated in each of the above steps, particularly the speed determined by the speed determination unit 156.
- the accuracy index is calculated by the following equation (9) using, for example, the value I1 of the luminance value extreme value Pmax (Pp1) and the value I2 of the luminance lower extreme value Pmin (Pp2) in the graph 62 of FIG. can do. When this value is smaller than a certain threshold value, it indicates that the speed determined in step S503 or S504 and the accuracy of various information calculated in steps S6 to S8 based on it are low.
- the calculated index a can be displayed on the display unit 14, whereby the examiner can determine whether or not remeasurement is necessary.
- calculation formulas (algorithms) of steps S501 to S504 and S6 to S9 described above are stored in advance in the memory unit 154, and the diagnostic information calculation unit 153 such as the speed determination unit 156 calculates the above numerical values. To read and calculate.
- Step S10> The diagnostic information calculated by the diagnostic information calculation unit 153 is displayed on the display unit 14. Details of the display will be described later.
- a model formula is set for each of the developed part and the undeveloped part of the aortic valve regurgitation, and the speed-luminance value relationship that is the result after the convolution calculation is established. Fitting the formula and the measured value. Thereby, the physically consistent speed can be accurately determined.
- the present embodiment the case where the aortic valve regurgitation is targeted as the desired blood flow part has been described. However, the present embodiment is similarly applied to not only the aortic valve regurgitation but also a blood flow part to which a jet model applies. can do.
- the configuration of the apparatus (FIG. 1) is the same as that of the first embodiment.
- a B-mode image is acquired, a measurement target region is set, and Doppler measurement is performed on the set measurement target region. This is the same as steps S1 to S4 in the first embodiment.
- the velocity determination unit 156 physically calculates the blood flow velocity desired by the examiner based on the tissue position information acquired by the shape extraction unit 151 and the velocity distribution information acquired by the flow velocity distribution acquisition unit 152. Determined by considering consistency.
- the speed determination unit 156 sets up an expression for estimating the position of a desired speed in a luminance value speed distribution graph of a system in which blood flows of a plurality of different speeds exist, and actually measured this expression.
- a desired speed is obtained by applying to the luminance value speed distribution.
- the speed determination unit sets a model represented by the sum of a step function and a delta function as a model of speed information, and uses the value of the singular point of the speed distribution acquired by the speed distribution acquisition unit.
- Speed information is calculated.
- the singular point used by the speed determination unit includes any one of a minimum value, a maximum value, and an inflection point of the speed distribution acquired by the speed distribution acquisition unit.
- FIG. 12 is a diagram showing a processing flow of the speed determining unit 156 of the second embodiment. Steps S1 to S4 and steps S6 to S10 are the same as those of the first embodiment, and thus description thereof is omitted. Details of step S5, which is a feature of the present embodiment, will be described below.
- Step S511 The speed determination unit 156 detects a singular point of the speed distribution information (the luminance value speed distribution 62 shown in FIG. 6B) acquired by the flow velocity distribution acquisition unit 152.
- the singular points are a luminance value decrease inflection point P1, a luminance value increase inflection point P2, a luminance value extreme value Pp (Pp1, Pp2), a luminance lower end P3, and the like. These singular points can be detected from the graph and by taking the derivative thereof.
- the speed of the singular point is obtained from the graph, and the process proceeds to the next step S512 to calculate the speed. At this time, if the luminance value extreme value Pp does not appear remarkably, it is highly possible that the signal strength of the jet has decreased, and the process proceeds to step S513.
- Step S512 In the luminance value / velocity distribution graph, there are several feature points detected in step S511, such as the luminance lower end P3, the luminance value decreasing inflection point P1, the luminance value extreme value Pp, and the luminance value increasing inflection point P2. However, the true value of the valve reverse flow rate is unknown. Therefore, in this step, it is assumed that the luminance value speed distribution is represented by the sum of the step function and the delta function, and the position where the true value of the peak position speed is obtained is estimated.
- the vicinity of the center of the jet shows a certain constant velocity, but when other velocity components including components in the opposite direction are present, the luminance value velocity distribution 103 as shown in FIG. It becomes. Further, a brightness value speed distribution 104 tanned by the characteristic function G of the apparatus is obtained.
- the brightness value speed distribution 104 qualitatively matches the brightness value speed distribution 102 in the sense that there is a peak of the brightness value, but the peak position 104p is shifted to a lower speed side than the maximum speed U in the region. ing. This is because it has been pulled by the surrounding speed. From this, it can be said that the peak of the luminance value does not necessarily indicate the jet velocity.
- the true value U of the velocity at the peak position can be represented by the following equation (10).
- U 1 is the speed of the luminance value reduction inflection point P1
- U 2 is the speed of the luminance value increase inflection point P2
- U p is the velocity of the values of the luminance values extreme Pp.
- Step S513 On the other hand, when the luminance value extreme value Pp does not appear remarkably, it is highly possible that the signal strength of the jet has decreased, but it is considered that the velocity distribution can be assumed by a step function, and the true value is obtained by the following equation (11). Find U.
- Expression (11) is not limited to aortic valve regurgitation, and can be applied to all cases where the velocity distribution can be assumed by a step function or the like.
- an ideal flow in a blood vessel is described by Expression (12), and its probability density function is a kind of step function.
- the equation (11) can be applied.
- Step S514 The accuracy calculation unit 157 may calculate the accuracy of the speed determined in steps S512 and S513 using the information on the luminance value extreme value Pp, similarly to step S9 described in the first embodiment.
- the calculated accuracy can be displayed on the display unit 14, whereby the examiner can determine whether or not remeasurement is necessary.
- various diagnostic information may be calculated in steps S6 to S10 using the determined speed.
- the true desired speed can be determined by a simpler method than in the first embodiment in which the desired speed by fitting is calculated. Further, the present embodiment can be applied to all objects that can represent the blood flow with a step function. Furthermore, in this embodiment, since the function of calculating the accuracy of the obtained result is provided, the examiner can confirm the accuracy of the determination result.
- FIG. 14 shows an example of a graph displayed on the display unit 14.
- FIG. 14A is a diagram showing an example in which the speed U of the time phase T desired by the examiner is displayed on the screen 140 that displays the Doppler waveform created by the flow velocity distribution acquisition unit 152.
- the speed U of the time phase T desired by the examiner is displayed on the screen 140 that displays the Doppler waveform created by the flow velocity distribution acquisition unit 152.
- the example shown in FIG. U is displayed as a numerical value in block 141.
- one or a plurality of luminance value decreasing inflection points P1, luminance value increasing inflection points P2, luminance value extreme values Pp, and calculated speed U in all or some time phases are displayed. May be displayed in a time series manner as a line 142 or as a point 143 superimposed on the Doppler waveform.
- the accuracy a of the speed search result may be displayed, or a threshold value may be set for accuracy a. If a is less than or equal to the threshold value, it
- FIG. 14B is an example in which part or all of the time phase of the pressure difference dP obtained in step S6 is displayed.
- the pressure difference at one or more times may be displayed in the block 145 together with the graph 144 showing the temporal change of the pressure difference.
- FIG. 14C shows a temporal change in the absolute pressure of each part obtained in step S7.
- the solid line is the left ventricle
- the dotted line is the aorta
- the two-dot chain line is the absolute pressure of the left atrium. Indicates.
- the speed determining unit 156 calculates the time constant ⁇ when the absolute pressure is differentiated with respect to time by dP / dt and / or the relaxation state of the left ventricle is approximated by an exponential function
- the block 146, 147 may display either or both of dP / dt and ⁇ at one or all of one heartbeat. Further, the progress of processing such as each step may be displayed in the box 148.
- FIG. 14D shows the pressure-volume relationship diagram obtained in step S8.
- Pressure - The volume relationship diagram in addition to the pressure-volume relationship curve C PV, pressure at systole end - E max is the slope of the volume relationship, end-diastolic pressure showing the relationship between end-diastolic pressure and volume - volume relationship curve C PV ED may be displayed.
- FIG. 14 shows a display example, and the present invention is not limited to the display example of FIG. 14, and various changes can be made.
- the information on the absolute pressure may be superimposed on the tissue image based on the image formed by the shape extraction unit 151.
- FIG. 15 shows the result of comparing the result with the pressure difference result using the pressure sensor.
- the solid line of the graph is the result of measurement using a pressure sensor
- ⁇ is the pressure calculated by the method of the second embodiment.
- blood flow velocity desired by an examiner can be accurately measured in ultrasonic imaging, and information useful for diagnosis such as pressure difference and absolute pressure can be accurately obtained using this velocity.
- information useful for diagnosis such as pressure difference and absolute pressure can be accurately obtained using this velocity.
- SYMBOLS 1 Apparatus main body, 2 ... Ultrasonic probe, 10 ... Input part, 11 ... Control part, 12 ... Ultrasonic signal generator, 13 ... Ultrasonic receiver circuit, DESCRIPTION OF SYMBOLS 14 ... Display part, 15 ... Signal processing part, 151 ... Shape extraction part, 152 ... Speed distribution acquisition part, 153 ... Diagnostic information calculation part, 155 ... Addition part, 156 -Speed determination part, 157 ... Accuracy calculation part, 158 ... Pressure difference calculation part, 159 ... Absolute pressure calculation part, 160 ... Volume calculation part.
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Abstract
Description
図1は、本発明による超音波撮像装置の装置構成例を示すブロック図であり、図1(a)は装置全体を示す図、(b)は信号処理部の一部である診断情報算出部の詳細を示す図である。図1(a)に示すように、本実施形態の超音波撮像装置は、装置本体1と超音波探触子2を有している。
<ステップS1>
まず、照射領域の形態情報(Bモード画像)を得るために撮像を行う。Bモード像の超音波周波数は、撮像が可能な1MHzから20MHzの範囲とする。また、心拍によって変動する組織撮像する際のフレームレートは心臓の動きを捉えることができる範囲である、20Hz以上とする。形状抽出部151は、超音波受信回路13から出力される反射エコーより、例えばBモード像、すなわち超音波照射対象の平面的撮像法を用いた2次元的な超音波生体画像あるいは立体的撮像法を用いた3次元的な超音波生体画像を形成する。このとき、超音波生体画像用のデータは時系列で取得される。
形状抽出部151において、ステップS1で形成した超音波生体画像より組織位置情報を取得する。組織位置の決定は、組織内壁を画像処理によって検出してもよいし、検者が入力部10を介して組織内壁を指定することで位置情報を取得してもよい。具体的には超音波画像では組織は高輝度値として認識されるため、高輝度値部を心臓組織とし、2次元、あるいは3次元的な心臓組織位置を取得する。あるいは、検者が入力部10に備えてあるポインティングデバイスを介し、血液と組織との境界面である組織内壁を指定することで、位置を与えてもよい。
次に、流速分布取得部152が、形状抽出部151で取得した超音波生体画像のなかの血流部に注目し、血流部位(超音波照射部内の全部あるいは一部)の速度分布情報(ドプラ波形)を取得する。
流速分布取得部152は、速度分布情報を取得するに際し、ドプラ波形の平均加算を行うことが好ましい。これにより、精度の向上を行うことができる。平均加算は、入力部10より心電図や心音図のタイミングを入力してもよいし、画像処理によってドプラ波形に対して相互相関を行ってもよい。心時相の検出には、図7に示すような種々の物理量を用いることができる。図7は、上から順に、心電図信号波形71、僧房弁流入速度波形72、肺動脈弁逆流波形73、心壁速度波形74、心壁運動波形75の変化を示している。心電図信号を用いた場合は、入力部10から取り込んだ心電図信号波形71による心拍時相が認識できる。その他の波形72~75については、ドップラー計測や経時的に計測したMモード画像から得ることができ、波形の極大値、極小値、最大値、最小値、傾き、ゼロクロスなどを用いることで、特定の時相76を検出することができる。
速度決定部156は、ステップS2で形状抽出部151が取得した組織位置情報と、ステップS3で流速分布取得部152が取得した速度分布情報をもとに、検者が所望する血流速度を物理的な整合性を考慮して決定する(S5)。
<<ステップS501>>
まず、目的とする血流について、速度の空間分布のモデルから、ある速度uを持つ流速の体積を推定し、速度uとその体積V(u)との関係を推定する。ここでは大動脈弁逆流を対象としているので、大動脈弁逆流を噴流であるとみなし、速度分布を予測する。大動脈弁噴流の速度分布は、図9に示すように、大動脈弁37の近傍では、中心部分(コア)の速度が突出し、その周辺との境界で不連続な変化があるが、大動脈弁37から離れたところでは、コアの周囲が滑らかになり周辺に連続的に連なるようになる。コア領域(平らな部分)が滑らかになった領域を噴流が発達した領域という。本実施形態では、コアが発達した領域と未発達な領域とを分けて、それぞれ、別のモデル式を立てて、それらを積算する。
社河内、噴流工学(2004)森北出版
ステップS501で算出した速度と体積との関係式をもとに、速度と輝度値との関係を求める。この計算は、式(3)の体積について、対数をとり、ガンマ関数などの調整を加えることにより実現できる。式(3)を用いて再現した速度分布(速度と輝度値との関係)を図10(a)に示す。この結果は、図10(b)に再度示す実測値(輝度値速度分布)62の点線部と比較して、良好な再現といえる。上記式(3)において、A、n、R、σ、Uは未知数であり、次のステップで実測値からフィッティングを行うことにより算出する。
ステップS502で求めた速度分布の式(式(3))と実測値62(図6(b))とをフィッティングし、式(3)の未知数を求め、所望の速度であるUを算出する。フィッティング方法は、最小二乗法、差分絶対値最小法、相互相関によるパターンマッチング等の公知の手法を用いることができる。なおフィッティングは、式(3)に対して畳み込み積分を行ったあとに行ってもよいし、畳み込み積分効果を考慮しないフィッティングの場合は、式(5)で畳み込み効果を補正しても良い。
一般に、ドプラ波形を生成する際は、どんなに均一な速度分布を計測したとしても、図5に示す速度分布53のように、装置に依存した幅を持つ。本ステップでは、装置に依存した速度分布の幅を補正する。具体的には、例えば、幅の特性関数Gが式(4)に示すガウシアン分布であり、その分散値がSである場合、補正後の速度は、式(5)で表わすことができる。
以上説明したステップS501~S504は速度決定部156により処理されるステップである。これらステップにより、所望の速度U(補正後はUc)が決定される。
算出された大動脈弁逆流の中心速度Uを基に、式(6)に示す簡易ベルヌーイ式から圧力較差dPを求める(圧較差算出部158の処理)。圧力較差を時相毎に求めることで、その時間変化の情報を得ることができる。
容積算出部160は、形状画像形成部151の形成した形状画像から複数の時刻において左心室の容積を算出する。左心室容積の算出には、左心室を回転楕円体と仮定し、二次元の撮像画像から得られた左心室の内径より求めるPombo法やTeichholz法などを用いることができる。あるいは、心臓の形状を3次元的に撮像することで、直接的に計測することも可能である。算出した複数の時刻における左心室容積Vと、ステップS5で算出した複数の時刻における絶対圧Pとの関係を表す圧-容積関係図を作成する。圧-容積関係図の一例を図11に示す。図中、複数のループ状の曲線は、検査対象について異なる身体的条件で測定した場合の圧-容積関係曲線CPVであり、1心拍で一つのループを示している。異なる身体的条件とは、例えば、下肢に負荷を与える前後、薬物の投与前後などである。これら圧-容積関係曲線CPVをもとに、収縮期末期における圧-容積関係の傾きEmaxや拡張末期圧と容積の関係を示す拡張末期圧-容積関係曲線CPV EDを表示してもよい。
診断情報算出部153は、ステップS6で算出した絶対圧から、時間的な微分値を示す物理量であるdP/dt及び/又は左心室の弛緩状態を指数関数で近似した際の時定数τを算出することもできる。ステップS6~S8で得られる値は、検査対象の心臓の状態を示す重要な診断指標となる。
精度算出部157は、上記各ステップで算出された診断情報、特に速度決定部156で決定された速度について、その精度を算出してもよい。精度の指標は、例えば、図6(b)のグラフ62の輝度値極値Pmax(Pp1)の値I1と輝度下部極値Pmin(Pp2)の値I2を用いて、次式(9)による算出することができる。
上記診断情報演算部153で算出された診断情報は、表示部14に表示される。表示の詳細は後述する。
本実施形態においても、装置の構成(図1)は第一実施形態と同様であり、また、まずBモード像を取得し、計測対象領域を設定すること、設定した計測対象領域についてドプラ計測を行うことは、第一実施形態のステップS1~S4と同じである。また本実施形態でも、速度決定部156は、形状抽出部151が取得した組織位置情報と、流速分布取得部152が取得した速度分布情報をもとに、検者が所望する血流速度を物理的な整合性を考慮して決定する。但し、本実施形態では、速度決定部156は、複数の異なる速度の血流が存在する系の輝度値速度分布グラフにおいて、所望の速度の位置を推定する式を立てて、この式を実測した輝度値速度分布に当てはめて、所望の速度を求める。
速度決定部156は、流速分布取得部152が取得した速度分布情報(図6(b)に示す輝度値速度分布62)の特異点を検出する。特異点は、具体的には、輝度値減少変曲点P1、輝度値増加変曲点P2、輝度値極値Pp(Pp1、Pp2)、輝度下端部P3などである。これらの特異点は、グラフから、またその微分を取ることで、検出することができる。グラフから特異点の速度を求め、次ステップS512に進み、速度を計算する。その際、輝度値極値Ppが顕著に現れない場合は、噴流の信号強度が低下している可能性が高く、ステップS513に進む。
輝度値速度分布グラフには、ステップS511で検出した、輝度下端部P3、輝度値減少変曲点P1、輝度値極値Pp、輝度値増加変曲点P2など、幾つかの特徴点が存在するが弁逆流の速度の真値は不明である。そこで本ステップでは、輝度値速度分布がステップ関数とデルタ関数の和で表わされると仮定し、ピーク位置の速度の真値が得られる位置を推定する。
本実施形態においても、速度決定に関する演算情報(式(10)、(11))はメモリ部154に格納されており、速度決定部156が速度決定時に呼び出す。
精度算出部157は、第一実施形態で説明したステップS9と同様に、輝度値極値Ppの情報を用いて、上記ステップS512、S513で決定された速度の精度を算出してもよい。算出された精度は、表示部14に表示させることができ、それにより検者は再計測の要否等を判断することができる。また決定された速度を用いてステップS6~S10で種々の診断情報を算出してもよいことは、第一実施形態と同様である。
上述した実施形態では、主として、所望速度の決定と求められた速度を用いた圧力情報の計算について説明したが、以下では、これら実施形態に共通する表示の実施形態を説明する。
図14(a)は、流速分布取得部152が作成したドプラ波形を表示する画面140に、検者の所望する時相Tの速度Uを表示した例を示す図で、図示する例では、速度Uはブロック141内に数値として表示される。また同ドプラ波形上に、全時相あるいは一部の時相における輝度値減少変曲点P1、輝度値増加変曲点P2、輝度値極値Pp、算出された速度Uのうち一つあるいは複数を時系列的に繋げてライン142として、あるいは点143としてドプラ波形に重ねて表示してもよい。またブロック141には、速度検索結果の精度aを表示してもよいし、精度aに閾値を設定し、aが閾値以下の場合は、計測精度が低い旨を表示してもよい。
Claims (18)
- 検査対象に超音波を送信するとともに前記検査対象から反射するエコー信号を受信する超音波探触子と、前記超音波探触子によって受信されたエコー信号を処理する信号処理部と、前記信号処理部による処理結果を表示する表示部とを備えた超音波撮像装置であって、
前記信号処理部は、前記エコー信号から前記検査対象に含まれる流体の速度分布を取得する速度分布取得部と、前記速度分布取得部で取得した速度分布から速度情報を決定する速度決定部とを備え、
前記速度決定部は、前記速度情報のモデルを設定し、前記モデルと前記速度分布取得部が取得した速度分布とが整合するように前記速度情報を決定することを特徴とする超音波撮像装置。 - 請求項1に記載の超音波撮像装置において、前記速度決定部は、前記モデルとして、流体の速度の空間分布を推定し、推定された速度の空間分布を、前記速度分布取得部が取得した速度分布と整合するように決定し、決定された速度の空間分布から前記速度情報を算出することを特徴とする超音波撮像装置。
- 請求項1に記載の超音波撮像装置であって、前記速度情報が心臓の弁逆流の速度情報であり、前記速度決定部は、前記モデルとして噴流モデルを用いることを特徴とする超音波撮像装置。
- 請求項3に記載の超音波撮像装置であって、前記速度決定部は、前記噴流モデルを、噴流の発達領域のモデルと噴流の未発達領域のモデルとの畳み込み演算によって作成することを特徴とする超音波撮像装置。
- 請求項4に記載の超音波撮像装置であって、前記速度決定部は、前記噴流の発達領域のモデルとして、Goretlerの式、Schilichtingの式、Tollmienの式のいずれかを用いることを特徴とする超音波撮像装置。
- 請求項4に記載の超音波撮像装置であって、前記速度決定部は、前記噴流の未発達領域のモデルとして、指数関数、ステップ関数、エラー関数、デルタ関数のいずれか、或いはそれらを組み合わせた関数を用いることを特徴とする超音波撮像装置。
- 請求項1に記載の超音波撮像装置において、前記速度決定部は、前記速度情報のモデルとして、ステップ関数とデルタ関数との和で表わされるモデルを設定し、前記速度分布取得部が取得した速度分布の特異点の値を用いて、前記速度情報を算出することを特徴とする超音波撮像装置。
- 請求項7に記載の超音波撮像装置であって、前記速度決定部が用いる前記特異点は、前記速度分布取得部が取得した速度分布の極小値、極大値、変曲点のいずれかを含むことを特徴とする超音波撮像装置。
- 請求項1に記載の超音波撮像装置であって、
前記検査対象の心周期情報を取得する周期情報取得部を備え、
前記速度分布取得部は、前記周期情報取得部が取得した心周期情報に基き、心周期毎に前記速度分布を取得することを特徴とする超音波撮像装置。 - 請求項9に記載の超音波撮像装置であって、
前記信号処理部は、前記速度分布取得部が心周期毎に取得した速度分布を加算する加算部を備え、
前記速度決定部は、前記加算された速度分布を用いて、前記速度情報を決定することを特徴とする超音波撮像装置。 - 請求項3に記載の超音波撮像装置において、
前記信号処理部は、前記速度決定部が決定した弁逆流の速度情報を用いて、弁内外の圧較差を算出する圧較差算出部を備えたことを特徴とする超音波撮像装置。 - 請求項11に記載の超音波撮像装置において、
前記信号処理部は、前記圧較差算出部が算出した前記圧較差と予め設定又は外部入力された基準圧から、絶対圧を算出する絶対圧算出部を備えたことを特徴とする超音波撮像装置。 - 請求項12に記載の超音波撮像装置において、
前記信号処理部は、前記絶対圧算出部が算出した左心室の絶対圧から、時間的な微分値(dP/dt)及び/又は左心室の弛緩状態を指数関数で近似した際の時定数τを算出する手段を備えたことを特徴とする超音波撮像装置。 - 請求項1に記載の超音波撮像装置において、前記信号処理部は、前記速度決定部が算出した速度情報及び/又は当該速度情報から算出した診断情報の精度を算出する精度算出部を備えたことを特徴とする超音波撮像装置。
- 請求項14に記載の超音波撮像装置において、
前記精度算出部は、前記速度分布取得部が取得した速度分布の極大値と極小値との差を用いて前記精度を算出することを特徴とする超音波撮像装置。 - 請求項12に記載の超音波撮像装置において、
前記信号処理部は、前記形状抽出部が抽出した左心室形状から当該左心室の容積を算出する容積算出部を備え、前記容積算出部が算出した左心室容積と、前記絶対圧算出部が算出した前記左心室の絶対圧とを用いて、圧-容積関係図を作成し、前記表示部に表示させることを特徴とする超音波撮像装置。 - 請求項16に記載の超音波撮像装置において、
前記容積算出部は、複数の異なる条件における前記圧―容積関係図を作成し、前記複数の圧―容積関係図を用いて、収縮期末期における圧―容積関係図の傾きEmax及び/又は拡張末期圧―容積変化曲線を作成し、前記表示部に表示させることを特徴とする超音波撮像装置。 - 超音波を照射した検査対象から反射するエコー信号を用いて、前記検査対象の診断情報を取得する超音波撮像方法であって、
エコー信号を用いて前記検査対象に含まれる流体の速度分布を取得するステップと、
前記流体の速度分布から目的とする速度情報を決定するステップとを備え、
前記速度情報決定ステップは、
前記目的とする速度情報のモデルを設定するステップと、
前記流体の速度分布から、前記モデルと整合する速度を検索し、決定するステップと、
決定した速度及び/又は当該速度から算出される診断情報を表示するステップと、
を含むことを特徴とする超音波撮像方法。
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EP2918232A1 (en) * | 2014-03-13 | 2015-09-16 | Samsung Medison Co., Ltd. | Method and apparatus for representing pressure variation in object |
JP7366829B2 (ja) | 2020-04-07 | 2023-10-23 | キヤノンメディカルシステムズ株式会社 | 装置及びプログラム |
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WO2016139515A1 (en) * | 2015-03-02 | 2016-09-09 | B-K Medical Aps | Non-invasive estimation of intravascular pressure changes using vector velocity ultrasound (us) |
WO2017163103A1 (en) * | 2016-03-21 | 2017-09-28 | Ultrasonix Medical Corporation | Visualization of ultrasound vector flow imaging (vfi) data |
CN106175832B (zh) * | 2016-06-27 | 2019-07-26 | 联想(北京)有限公司 | 一种检测血压的方法及移动终端 |
EP3418972A1 (en) * | 2017-06-23 | 2018-12-26 | Thomson Licensing | Method for tone adapting an image to a target peak luminance lt of a target display device |
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