# Method and device for measuring blood circulation velocity

FIELD: medicine; medical engineering.

SUBSTANCE: method involves applying ultrasonic Doppler echolocation techniques for scanning blood circulation at selected area of cardiovascular system, determining blood circulation velocity vector projections and calculating blood circulation speed. Echolocation is carried out by using at least three non-complanar probing ultrasonic rays set at angles relative to selected area of cardiovascular system in the range of 0-±80°. Selected blood circulation area orientation angles are measured relative to scanning ultrasonic rays and Doppler frequency shifts in each measuring channel are determined. Blood circulation speed is calculated as where ω_{0i} is the radiation frequency of ultrasonic oscillation in ray I, Δω_{i} is the Doppler frequency shifts in measuring channel i, V is the ultrasonic wave propagation speed in the medium, ϑ_{k} is the blood circulation speed in selected area, ϑ_{ki} is the blood circulation velocity projection to scanning ray i, a,b,c,h,k,n_{11},n_{12},n_{13} are the coefficients depending on ultrasonic rays orientation. The device has measuring unit having ultrasonic transducers and electronic unit having switch, high frequency oscillator, calculating unit, indication and control unit. The measuring unit is manufactured as bracelet which segments are connected to each other by means of adjustable hinges and has gages for measuring lateral segment orientation angles relative to the central segment and gages for measuring ultrasonic transducer orientation angles relative to the i-th segment where i = 1,2,3, connected to calculating unit, switch, indication and control unit connected to high frequency oscillator, ultrasonic transducers of the measuring unit are connected via the switch to the high frequency oscillator.

EFFECT: high accuracy of measurements; wide range of functional applications.

2 cl, 2 dwg

The invention relates to the field of medicine and medical equipment and can be used to measure the velocity of blood flow in nuclear medicine for cardiac diagnostics and the study of hemodynamics non-invasive method.

Known widely used in practical medicine how to determine the speed of blood flow in some areas of the cardiovascular system (CVS)based on the method of Doppler ultrasonic echolocation. The principle of measurement of flow velocity on separate sections of the CCC on the basis of echolocation is to use the Doppler effect, which determines the dependence of the Doppler frequency shift (Δω) probe and the reflected ultrasonic beams (UZ-rays) from the measured flow velocity (ϑ_{k}).

As analogues of the proposed method can be adopted U.S. patents [1], [2]. Analysis of existing analogues of methods for determining blood flow velocity based on the method of echolocation shows that they are characterized by a General principle disadvantage consists in the fact that, in reality, taking into account mutual spatial orientation of the velocity vector () relative to the direction () probing ULTRASONIC beam and unambiguous correlation between the values ϑ_{k}and Δω disturbed, it requires knowledge of the corners of interaction is me orientation vectors (
and). Neglect of this factor leads to the manifestation in practice of methodological errors in the determination of the flow velocity (ϑ_{k}), which will be greater, the greater the spatial angledifferent from zero, i.e. from the condition of collinearity of the vectorsand.

To limit the influence of this factor on the accuracy of the measurement of blood flow velocity in the existing methods echolocation limit the angle between the direction defined by the flow velocity ϑ_{k}and directionthe probing ULTRASONIC beam within quantities not exceeding 20°. However, this condition is difficult to follow and it greatly restricts the selection and exploration of the CAS, in which you want to determine the velocity of blood flow. Knowledge of the orientation angles of the investigated area of the flow relative to the reference coordinate system can contribute to research in SSA, as well as obtaining information about blood flow velocity ϑ_{k}with high accuracy (without modeling errors).

In other words, the existing methods and devices for determining the flow velocity on the basis of echolocation (analogues of way) give incomplete information about what the parameters of blood flow in the studied plots CCC, as they allow you to define only

the magnitude of the flow velocitymodulo (with considerable methodological errors of up to several units - tens of percent) and do not allow to determine the orientation in space of the investigated areas of the vascular system.

Closest to the proposed invention relating to the method of measuring characteristics of blood flow, is a U.S. patent [3], adopted for the prototype. This method is based on the method of echolocation using one ULTRASONIC beam. Moreover, the information about the longitudinal (axial) component of the flow velocity is obtained based on the Doppler effect, and the information about the transverse components of the flow velocity due to lateral flow of blood is obtained based on the method of chronometry by measuring the time of lateral flow of liquid to the width of the ULTRASONIC beam in the study area CCC. The measured longitudinal and transverse components of velocity information is generated on the three-dimensional velocity of blood flow.

The disadvantages of the prototype are the low accuracy of determination of the longitudinal component of the flow velocity (due to the manifestation of methodological errors of measurement - up to tens of percent), low accuracy of determination of the transverse components of the IC is to grow blood flow (perpendicular directions relative to the probing ULTRASONIC beam), due to large errors in determining the width of the ULTRASONIC beam, and the limited scope of the proposed method (prototype) regimes of laminar fluid flow. In particular, the last disadvantage of the prototype will not allow it to be used for those portions of the CAS, where the regime of turbulent flow (aorta, arteries, arterioles, veins and venules), and not laminar (capillaries). Thus, the prototype of the invention has a narrow scope and limited in practice by the fluid flow regime.

Also known system for measuring the directional components of velocity of the organs, including blood flow, ultrasonic sensors, forming together with the switching node and the evaluator independent measurement channels and computation [4]. However, a disadvantage of this device (taken as a prototype) is the inability of the proposed method of determining the velocity of blood flow due to inconsistent measurement of longitudinal (along the ULTRASOUND beam) and transverse (normal to the propagation direction of ULTRASONIC beam) components of the flow velocity. In turn, the inconsistency of the work of measuring channels is due to the fact that the primary information for the three measuring channels is formed on the basis of one (but scanning) UZ-Lou who and. Therefore, the processing of ULTRASONIC information in this unit is limited only to the determination of the directional components of velocity of motion of bodies and the calculated cross-correlation functions of these components.

The proposed invention aims to expand the scope of medical practice method and device for ultrasonic diagnosis. To obtain such a technical result and increase the accuracy of measurement of blood flow velocity in the proposed method of measuring blood flow velocity, based on the method of echolocation, additionally determine the angular orientation of the investigated area of the cardiovascular system with respect to three of the probing ULTRASONIC beams, fixing the orientation angles of ULTRASONIC beams relative to the investigated area CCC in the range of 0° up to ±80°corresponding Doppler shifts of frequencies Δω_{i}and the velocity of blood ϑ_{k}determined taking into account the measured orientation angles and Doppler shift frequencies Δω_{i}in accordance with the expression

where ω_{0i}the emission frequency of the i-th ULTRASONIC beam,

Δω_{i}- Doppler shift frequency of the i-th reflected ULTRASONIC beam relative to the i-th probing ULTRASONIC beam,

V - velocity of propagation of ULTRASONIC waves in the medium (for soft biological tissue and V=1540 m/s)

ϑ_{ki}the projection of the velocity vector of the blood flowat the direction of the i-th ULTRASONIC beam,

a, b, c, h, k, n_{11}n_{12}n_{13}are coefficients that depend on the orientation angles of ULTRASONIC rays.

Distinctive features of the proposed method are

- measurement of the orientation angles of the investigated area of the blood flow in space relative to the probing ULTRASONIC rays,

- measurement of blood flow velocity not less than three channels in the space of non-coplanar probing ULTRASONIC beams installed at angles relative to the area of the CAS in the range of 0°...±80°.

These distinctive features allow you to improve the accuracy of measuring the speed of blood flow, to expand the scope of application of the method regardless of the current flow and to obtain additional information about the angular orientation of the investigated plots of CVS.

To achieve the mentioned technical result is a device that represents a measurement unit consisting of the measuring unit with ultrasonic sensors, angle sensors and an electronic unit, comprising a generator of high frequency switch, the transmitter unit display and control.

Distinctive features of the proposed device is that measuring the lock is made in the form of a bracelet, sections which are interconnected by adjustable hinges, and includes the sensor orientation angles of the side sections relative to the Central section and the sensor orientation angles of the ultrasonic sensors relative to the i-th section (where i=1, 2, 3)connected to the computer connected to the switch, the unit display and control.

The invention is illustrated by the drawings. Figure 1 shows the functional diagram of the proposed device. Figure 2 presents the layout of the measuring unit (made in the form of a bracelet) on the patient (on the hand).

The proposed device consists (see figure 1) of the measuring unit 1 with ultrasonic sensors (USD) and angle sensors (DU) 2, 3, made in the form of a bracelet (see figure 2), and electronic unit consisting of a switch 4, a generator of high frequency 5, a transmitter 6, a block indication and control 7. Section of the measuring unit (bracelet) 1 are interconnected by means of adjustable hinges (not shown). The angle sensors are used to measure angles β_{j}(j=2, 3) orientation of the side sections (j=2, 3) relative to the Central (j=1) partition (DN-2) and angles α_{i}(i=1, 2, 3) orientation of the USD relative to the i-th section (DN-3).

The sensor orientation angles of the ultrasonic sensors (DN-3) relative to the respective sections are connected with vychislitel, connected to the switch 4, the display unit and control 7 and connected to a generator of high frequency 5. Thus the ultrasonic sensors ultrasonic measuring unit 1 is connected through the switch 4 to the generator high frequency 5.

As a computing unit 6 can be used universal computer type IBM AT/XT or Apple Macintosh with a keyboard and other peripherals.

The proposed method is as follows. The system of n (n≥3) ultrasonic beams interacts with a specific point of the selected area of the cardiovascular system. Mechanical interaction of each of the probing ULTRASONIC beams with the flow at this point of the plot CCC leads to Doppler effect and the corresponding Doppler frequency shift of the probe and reflected rays. Record the angles of orientation of ULTRASONIC rays.

For implementing the method measuring unit (bracelet) attached to the area of the human body where you want to measure parameters of blood flow in arterial or venous sections of the CCC. The device can operate in one of two modes: configuration mode and operational mode (mode identification of blood flow).

In configuration mode the measuring unit and the electronics unit configured to perform an acoustic contact all n (n≥3) ultras ukovich rays from one point of the selected area of the cardiovascular system. This condition is satisfied, if the algorithm is implemented settings:

where H_{1}; H_{2}; θ - the design parameters of the sections of the measuring unit,

α_{1}- angle settings of ULTRASONIC sensor of the middle section,

l - distance from the DRAINAGE of the middle section to the reference point of the vessel,

α_{2}that α_{3}the orientation angles of the ultrasound of the side sections.

The distance l is determined using an ULTRASONIC sensor of the middle section by switching the mode ultrasonic rangefinder echolocation.

The corners of the mutual orientation of β_{2}and β_{3}the side sections with ULTRASONIC sensors SPL-2 SPL-3 relative to the Central section is determined by the angle sensors 2. Corners α_{i}() orientation of ULTRASONIC sensors in the azimuth set by the turns of the sensors relative to the sections and are controlled by the angle sensors 3 (scales). Signals proportional to the values of sin α_{I}; cosα_{i}(is injected into the transmitter 6.

In the operating mode (mode identification of blood flow) ULTRASONIC sensors SPL-1 SPL-2 SPL-3 alternately connected through the switch 4 to the generator 5 and provide echolocation ultrasound Doppler, blood flow and realized who and in the control point of the selected area of the cardiovascular system.
Thus due to the switching of each ULTRASONIC sensor alternately mode emitter, and then - in the mode of the receiver there are three Doppler frequency shift Δω_{0}()

From the expression (3) find the projection of the velocity vector.

Based on measurements of angles α_{i}(), β_{j}(j=2, 3) and calculate the components of velocity ϑ_{ki}(for a system of three Doppler ULTRASOUND beams can be vector-matrix equation

where N is a square matrix (3×3),

- unknown and given vectors.

ϑ_{k}- the module of the velocity vector of the blood flow,

α; β - the orientation angles of the vector ϑ_{k}.

Moreover, the coefficients of the matrix N depend on the orientation angles Θ, α_{i}that β_{j}.

Contacting the vector-matrix equation (5) we find the desired solution

where N^{-1}- inverse of the matrix.

The algorithm for identifying the parameters of blood flow (ϑ_{k}; α; β)that implements the solution (7)can be found based on the method of Kramer.

The identification algorithm in the form of the relations (8), (9) is implemented using a computer.

In contrast to existing methods, ultrasonic Doppler echolocation, allowing you to specify only one parameter flow (speed ϑ_{k}), with significant methodological errors caused by the neglect of a particular orientation vectorin space relative to the meter, the proposed method provides more complete(ϑ_{k}α β) and reliable (accurate) information about speedflow.

Sources of information

1. U.S. patent No. 5363851 A. Estimation of the flow velocity. Publ. 15.11.94.

2. U.S. patent No. 5373847 A. Method of color dopplerography for the study of blood flow in a patient. Publ. 20.12.94.

3. U.S. patent No. 5390677 a Method and apparatus for determining and displaying the three-dimensional velocities of blood. Publ. 21.02.95 (prototype method).

4. U.S. patent No. 5000184. System for measuring the directional components using ultrasound. Publ. 19.03.1991 (prototype devices).

1. The method of measuring the speed of blood flow by ultrasound Doppler echolocation blood flow in a selected area of cardio-with udisti system, determine the projection of the velocity vector of the blood flow and calculating the flow velocity, characterized in that the echolocation of blood flow in a selected area to be held not less than three non-coplanar probing ultrasonic beams mounted at angles with respect to the selected area of the cardiovascular system in the range from 0 to ±80°to measure the orientation angles of the selected area of the flow relative to the probe ultrasound and Doppler shifts of the frequencies for each channel, and calculates the flow velocity in accordance with the expression

where i=1, 2, 3,

ω_{0i}- frequency radiation of ultrasonic oscillations in the i-th beam,

ω_{i}- Doppler frequency shift in the i-th measurement channel,

V - velocity of propagation of ultrasonic waves in the medium,

ϑ_{k}- speed of blood flow in a selected area,

ϑ_{ki}- projection of the velocity of blood flow at the i-th - probing beam,

a, b, C, h, k, n_{11}n_{12}n_{13}- coefficients depending on the orientation angles of the ultrasonic beams.

2. Device for measuring the speed of blood flow, containing the measuring unit with ultrasonic sensors and an electronic unit including a switch, a generator of high frequency, the transmitter unit Indyk is tion and management, characterized in that the measuring unit is made in the form of a bracelet, the sections of which are connected by adjustable hinges, and includes the sensor orientation angles of the side sections relative to the Central section and the sensor orientation angles of the ultrasonic sensors relative to the i-th section, where i=1, 2, 3, connected to the computer connected to the switch, the display unit and the control and connected to a generator of high frequency, while ultrasonic sensors measuring unit connected through a switch to a generator of high frequency.

**Same patents:**

FIELD: medicine, urology.

SUBSTANCE: one should conduct subcutaneous prevocational tuberculin test and, additionally, both before the test and 48 h later it is necessary to perform the mapping of prostatic vessels and at decreased values of hemodynamics one should diagnose tuberculosis. The information obtained should be documented due to printing dopplerograms.

EFFECT: more reliable and objective information.

1 ex, 1 tbl

FIELD: medicine.

SUBSTANCE: method involves carrying out ultrasonic scanning examination of subclavian artery over its whole extent in physiological arm position with arterial blood pressure being measured in the middle one third of the arm. Next, when applying compression tests, blood circulation parameters variations are recorded in distal segment of the subclavian artery with arterial blood pressure being concurrently measured. Three degrees of superior thorax aperture syndrome severity are diagnosed depending on reduction of linear blood circulation velocity and arterial blood pressure compared to their initial values. Mild one takes place when linear blood circulation velocity reduction reaches 40% and arterial blood pressure 20% of initial level, moderate one when linear blood circulation velocity reduction reaches 70% and arterial blood pressure 50% and heavy one when linear blood circulation velocity reduction is greater than 70% of initial level and arterial blood pressure is greater than 50% to the extent of no blood circulation manifestation being observed in the subclavian artery.

EFFECT: high accuracy of diagnosis.

FIELD: medicine; medical engineering.

SUBSTANCE: method involves applying ultrasonic Doppler echolocation techniques for scanning blood circulation at selected area of cardiovascular system, determining blood circulation velocity vector projections and calculating blood circulation speed. Echolocation is carried out by using at least three non-complanar probing ultrasonic rays set at angles relative to selected area of cardiovascular system in the range of 0-±80°. Selected blood circulation area orientation angles are measured relative to scanning ultrasonic rays and Doppler frequency shifts in each measuring channel are determined. Blood circulation speed is calculated as where ω_{0i} is the radiation frequency of ultrasonic oscillation in ray I, Δω_{i} is the Doppler frequency shifts in measuring channel i, V is the ultrasonic wave propagation speed in the medium, ϑ_{k} is the blood circulation speed in selected area, ϑ_{ki} is the blood circulation velocity projection to scanning ray i, a,b,c,h,k,n_{11},n_{12},n_{13} are the coefficients depending on ultrasonic rays orientation. The device has measuring unit having ultrasonic transducers and electronic unit having switch, high frequency oscillator, calculating unit, indication and control unit. The measuring unit is manufactured as bracelet which segments are connected to each other by means of adjustable hinges and has gages for measuring lateral segment orientation angles relative to the central segment and gages for measuring ultrasonic transducer orientation angles relative to the i-th segment where i = 1,2,3, connected to calculating unit, switch, indication and control unit connected to high frequency oscillator, ultrasonic transducers of the measuring unit are connected via the switch to the high frequency oscillator.

EFFECT: high accuracy of measurements; wide range of functional applications.

2 cl, 2 dwg