WO2008101684A1

WO2008101684A1 - Method and device for the ultrasonography of blood flow

Info

Publication number: WO2008101684A1
Application number: PCT/EP2008/001318
Authority: WO
Inventors: Thomas Buck; Philipp Kahlert; Björn PLICHT
Original assignee: Universität Duisburg Essen
Priority date: 2007-02-21
Filing date: 2008-02-20
Publication date: 2008-08-28
Also published as: DE202008003245U1; DE112008000493A5

Abstract

The invention relates to a method and a device for the ultrasonography of blood flow through a cardiac valve. The measured values are determined from a colour Doppler data record, with aliasing taken into consideration.

Description

Method and device for ultrasound measurement of blood flow

The present invention relates to a method for ultrasonic measurement, a device for ultrasonic measurement and a use of a color Doppler patensatzes.

In particular, the present invention relates to the ultrasonic measurement of blood flow in the human or animal body through a dynamic or irregular opening, such as an insufficient or stenosed heart valve, a narrowed vein or artery, or the like. For example, it is desirable to determine the volume flow and / or the flow volume in the case of a diseased heart valve, in particular the return flow through a diseased heart valve, in order thereby to determine the severity of a valve defect and if necessary to be able to perform a heart valve operation with an optimal result.

WO 00/51495 A1 and WO 2004/075754 A1 disclose ultrasonic measuring methods in which pulsed ultrasonic signals are emitted and the backscattered ultrasonic beams are evaluated based on the Doppler technique.

Further devices for ultrasonic measurement are known for example from US Pat. No. 6,464,642 Bl, US Pat. No. 6,423,006 B1, US Pat. No. 6,293,914 Bl, US Pat. No. 5,676,148 A1, US Pat. No. 5,085,220 A, US Pat. No. 4,873,985 A, US Pat. No. 4,519,260 A, WO 2005/023098 A1 and JP 2006-014891 A1 known.

In the following, the primary focus is on the ultrasound measurement on the heart - ie echocardiography. However, the present invention is not limited thereto. Rather, the present invention can also be used in other ultrasonic measurements, in particular for the examination of the human or animal body.

To be able to better understand the present invention, firstly known ultrasound measuring methods, as are used in particular for echocardiography, will be explained in more detail. This procedure will be explained later also referred to in description of the invention. The procedures are described in particular in "Echocardiography" by PD Dr. med. med. Thomas Bartel and dr. med. Silvana Müller, Urban & Fischer Verlag, 1st edition 2007, pages 13 to 46, explained.

In the so-called M-mode technique, ultrasonic pulses are emitted by a transducer, in particular a so-called transducer (transmitter and receiver), and received again when reflected. After transmission of a pulse, a pause occurs until all reflections of the pulse are received before the next pulse is sent out. The frequency with which the pulses can be transmitted one after the other is referred to as pulse frequency or Pulse Repetition Frequency (PFR). The PRF depends on the duration of a pulse up to the selected penetration depth and the same transit time for the reflection. The running time is calculated from the speed of the ultrasonic pulses in the tissue and the running distance or penetration depth. The PRF is usually in the kHz range and is for example about 7.5 kHz. An advantage of the M-mode technique is a high temporal resolution of about 0.3 to 1.0 ms. As a result, even fast movements of small structures, such as the oscillating motion of a damper sail, can be represented as a fluid movement.

2-D echocardiography allows the real-time display of sector-shaped sectional images of the heart. Here, the transmission and reception direction of the ultrasonic signals in a sector of, for example, 90 ° is changed. By a fast pivoting movement of the transmission-reception direction, a sector image is composed of the one-dimensional scan line information. The number of these scan lines and thus the lateral resolution of the slice image are determined by the PRF, the frame rate and the sector angle.

3-D echocardiography enables the spatial, dynamic representation of the heart. Spatial image data records are generated. Basically, this can be done by composing a plurality of 2-D slice images, whereby a volume data set is done by computer-based reconstruction. By means of special transducers, in particular so-called phased-array transducers, the direct ultrasound measurement in a three-dimensional space region, in particular in a pyramidal Sound volume, allows. Modern matrix transducers consist, for example, of a two-dimensional arrangement of approximately 3,000 ultrasound elements. Through appropriate data processing, it is possible to scan pyramidal sound volumes of about 90 ° lateral extent and 30 ° width and display the ultrasound image information in real time. This allows real-time 3-D image data sets to be generated.

Doppler echocardiography or the Doüüler method allows the determination of blood flow velocities. It is primarily not an imaging technique, but rather a velocity measurement technique. Here, the so-called Doppler effect is exploited, ie the frequency shift of the reflected ultrasonic signal, which is also referred to as the Doppler signal for short. This frequency shift is proportional to the speed of movement of the reflecting object relative to the ultrasound receiver. This frequency shift is also referred to as Doppler frequency.

Three Doppler methods are known, namely the continuous Doppler method, pulsed Doppler methods and the color Doppler method.

In the continuous Doppler method, ultrasonic waves are continuously emitted and continuously received after reflection from other sound elements. Due to the continuous reception, the determination of very high flow velocities of up to 8 m / s is possible. However, there is no unambiguous local assignment of the registered movement possible. A speed spectrum is generated. Therefore, continuous Doppler is also referred to as spectral Doppler. Each pixel within the velocity spectrum represents one speed and one time. The more objects flow at the same speed, the greater the ultrasonic energy at this Doppler frequency and the corresponding brighter the corresponding pixel is displayed. Therefore, for example, the Doppler spectrum of severe mitral regurgitation is much brighter than that of low mitral regurgitation because the Doppler beam, with greater mitral valve leakage, detects a larger flow area with larger numbers of reflective blood cells. The intensity of the Doppler spectra thus give an indication of the size of the regurgitation flow (reflux) and thus the severity of mitral insufficiency. However, due to the detection of different flows along the Doppler beam, quantification of only the regurgitation flow is not possible.

Compared to the continuous Doppler method, the pulsed Doppler method along the ultrasonic steel allows a clear local assignment of the Doppler velocities. However, only speeds up to about 2 to 3 m / s can be determined. As with the M-mode technique, the PRF for the Doppler pulses depends on the distance to the object to be measured and on the propagation velocity of the ultrasound. In the pulsed Doppler method, the maximum measurable phase shift depends on the PRF. In order for the Doppler frequency, which corresponds to the phase shift, to be detected by means of the ultrasonic pulses, the PRF must correspond to at least twice the Doppler frequency. In addition, the maximum detectable speed - generally and subsequently as Nyquist speed - depends on the PRF. The higher the PRF, the lower the Nyquist speed. Thus, for example, at a PRF of 5 MHz and a distance of 7 cm, a Nyquist velocity of about 0.85 m / s results. If the Nyquist velocity is exceeded, several measurement windows may be created (thereby losing the uniqueness of the local assignment of the velocities), or the velocities above the Nyquist velocity will repeat the velocity spectrum or Nyquist spectrum (this will cause uniqueness lost speed determination - this pass is hereafter referred to as aliasing).

Usually, the speed scale is maintained within the Nyquist limits to provide a clear location mapping of speeds. If the Doppler frequency is too large compared to the PRF, the Doppler frequency and thus the speed can not be clearly detected. The effect of aliasing occurs. It should be noted here that the pulsed Doppler method or a pulsed Doppler device can detect not only the velocity of the moving object but also the direction of the velocity-that is, the direction of flow-based on the phase shift. If the Doppler frequency is the Nyquist Exceeds limits of +/- ¹ A PRF, no unambiguous velocity or speed direction more can be assigned. It then follows a misrepresentation.

In Doppler mode, it is usually possible to abandon the information of the direction of movement in favor of higher speeds. Instead of measuring and displaying velocities in the positive and negative directions, it is possible to record the doubling frequencies (ie velocities) in one direction up to the PRF (Nyquist limit). This scale shift is also referred to as a zero line shift.

The pulsed Doppler method, like the continuous Doppler method, also permits the registration of the different speeds of a flow in the form of a speed spectrum. In the case of the pulsed Doppler method, due to the measuring window with a certain depth range, a high proportionality between the reflected ultrasonic energy and the size of the reflective flow cross section (here also referred to as cross-sectional area), whereby a quantification of the flow cross section and the amount of flux on the basis of the Doppler spectra is possible in principle.

The color Doppler method allows a two- or three-dimensional color-coded representation of velocities, in particular blood flows, in combination with 2-D or 3-D echocardiography. Because of the physical limitations imposed by the PRF on the Doppler technique, it is impossible to assign accurate flow velocities to all pixels along an image line.

The color Doppler process is basically based on the principle of the pulsed Doppler process. Instead of registering the entire speed spectrum in one measuring point, in the color Doppler method, several pulses are transmitted successively per measuring point and only the phase shift between two successive reflecting pulses is compared (autocorrelation). These phase shifts are averaged to determine an average flow velocity of the particular measurement point. The larger the PRF and thus the number of phase shifts the more accurate (sensitive) is the determination of the mean velocity. The larger the PRF, the more the frame rate drops. The average speeds are color-coded according to the height and direction of the speed. Dark red to light yellow usually encodes speeds from 0 to half the (positive) Nyquist velocity toward the transducer and dark blue to light blue from 0 to half (negative) Nyquist velocity away from the transducer.

Due to the desired spatial resolution, the color Doppler method is subject to the same limitation of the maximum Nyquist velocity with the effect of aliasing as the pulsed Doppler method. However, the Nyquist speed of the color Doppler method is somewhat lower for the same settings than for the pulsed Doppler method, since some of the pulses are needed for image generation and thus the PRF for the color Doppler method decreases.

The average speeds are represented by a color coding, in particular as already explained above. This results in particular a color wheel. If the Nyquist limit or speed is exceeded, a color change or color change takes place, for example from light blue to yellow, when the flow is away from the transducer or from yellow to light blue when the transducer is flowing. The higher the average speed, the more often the color wheel is traversed or the color changes. In this case, one can also speak of multiple aliasing.

In the present invention, the term "aliasing" in particular not only to understand that a color change or color change has taken place, but how often. Aliasing or a corresponding aliasing value thus indicates how often the Nyquist velocity has been exceeded or the color gamut has been traversed.

Based on the color Doppler method, the so-called PISA method is known. The regurgitation flow is determined on the basis of the hemispherical flux convergence in front of a flow-through opening. The hemispherical area in front of the opening is detected by means of the color change limit due to the color change during aliasing. The area thus determined is with the Multiplied by the Nyquist velocity, which results in the volume flow of the fluid through this area and thus through the opening. For details, refer to "Echocardiography", page 41/42, and the references cited therein. A problem with the PISA method is that in many cases the aliasing boundary is not hemispherical and that the hemisphere of the aliasing is also subject to an angle error, the so-called Doppler angle error (deviation of the direction of flow from the ultrasound direction).

In the present invention, the term "volume flow" refers to a volume of fluid, such as blood, flowing per unit time. The volume flow results in particular from the product of the speed (flow velocity or flow velocity) of the fluid and the cross-sectional area through which the fluid flows. At velocities varying over the cross-sectional area, it is integrated over the cross-sectional area.

The "flow volume" refers to the volume of liquid that has flowed over a period of time. With varying volumetric flow, this results in particular from the integral of the volumetric flow over the desired time span.

In order, for example, to determine the volume flow, the flow volume and / or a value proportional thereto-also referred to below as measured values-of the blood return flow, the measuring range within the vena contracta (jet constriction) should be in the return flow of the blood through the heart valve.

In the present invention, the term "measuring range" refers to that spatial area which is sonified by a transmitting beam, ie sonicated, and whose backscattering is detected and evaluated, with possibly only the backscattering of a subarea being detected and / or evaluated. The backscattered ultrasonic waves are also referred to simply as ultrasonic signals or Doppler signals.

The present invention is based on the object, a method and an apparatus for ultrasonic measurement of a volume flow and / or Flow volume through an opening and a use of a color Doppler data set, wherein a simple, preferably automated measurement, especially at a relatively large and / or irregularly shaped and / or dynamic opening, using the color Doppler method even at flow rates above the Nyquist speed.

The above object is achieved by a method according to claim 1, a device claim 10 or a use according to claim 16. Advantageous developments are the subject matter of the subclaims.

One aspect of the present invention is that a two- or three-dimensional distribution of the velocity of the fluid is measured by the color Doppler method. The measuring range is preferably in and / or after a particularly dynamic and / or irregular opening through which the fluid flows. Particularly preferably, the measuring range is in the range of a vena contracta. This records a record with color-coded velocities.

The zero line of the color coding of the data set is adapted so that no color change occurs at the color-coded speeds in the measuring range.

Alternatively or additionally, the aliasing of the color coding is determined. This is done in particular by detecting how often the Nyquist velocity is exceeded by a velocity, in particular a maximum or average velocity, in the measuring range. In particular, this speed is determined separately and / or absolutely, more preferably by means of the continuous Doppler method. However, any other method may be used for this determination.

Finally, the volume flow and / or the flow volume is measured from the color-coded velocities of the adapted data record-that is to say with the adapted color coding-taking into account the aliasing and the Nyquist velocity and / or taking into account the absolute velocity. Preferably, the color-coded velocities are displayed after adjusting the color coding in a color image. Particularly preferably, the volume flow and / or the flow volume can also be displayed at the same time.

Instead of the volume flow or flow volume, measured values in the sense of the present invention, ie, for example, also values proportional thereto or dependent thereon can be displayed.

Further advantages, features, properties and aspects of the present invention will become apparent from the following description of a preferred exemplary embodiment with reference to the drawing. It shows:

1 is a schematic representation of a proposed device in the ultrasonic measurement of the return current through an inefficient heart valve;

FIG. 2 shows a schematic illustration of an ultrasound measurement of a vena contracta in an opening; FIG. and

Fig. 3 is a Doppler spectrum of a vena contracta.

Fig. 1 shows a schematic representation of a proposed device 1 and a proposed method for ultrasonic measurement of a fluid flow through a particular dynamic and / or irregular opening 2, which is flowed through by a fluid, in particular blood 3.

Fig. 1 shows schematically a body 4 only partially indicated with a heart to be examined 5, which is traversed by blood 3. A heart valve - here the mitral valve M - is insufficient and therefore does not completely close during the contraction of the ventricle (referred to below as systole), but forms the opening 2 schematically indicated in FIG. 1. During systole, blood 3 flows back through the opening 2 ,

By means of the proposed device 1 and the proposed method, measured values, namely the time during the measuring or Flow period varying volume flow of the backflowing blood 3, the total flow volume of backflowing blood 3 and / or a proportional thereto or dependent thereon, are determined.

However, the proposed method is not limited to the determination of the measured values in the case of a mitral valve, but can be used to determine the measured values in each heart valve or in any other dynamic and / or irregular opening 2, in particular blood 3, for example a hole in the heart septum, a stenosed vein or artery or the like. Moreover, the proposed method is not limited to the determination of the measured values in a single opening 2, but can the measured values of several openings 2 sequentially - for example, during the systole in an insufficient mitral valve and during diastole (relaxation and filling of the heart chamber) at an inadequate aortic valve - or simultaneously - for example, if there are two orifices 2 in an insufficient mitral valve, or if there is an insufficient mitral valve and a stenosed aortic valve.

Fig. 2 schematically illustrates the basic principle of ultrasonic measurement. The schematically indicated opening 2 is traversed by a fluid, such as the blood 3, wherein after the opening 2, a region 6 forms with at least substantially laminar flow, which tapers, so a Strahlentschnürung or -Verengung shows and therefore as vena contracta. This laminar region 6 runs depending on the shape of the opening 2 pointed, possibly conical, and is increasingly in a turbulent flow.

In particular, the proposed method relates to the measurement in the region of a vena contracta with a jet constriction of a factor of 0.65 to 0.85 (area or diameter of the tapered region 6 to area or diameter of the opening 2).

Pulsed ultrasonic signals 7 are emitted, as indicated in FIG. 2, and the backscattering of ultrasonic Doppler signals 8 is detected and evaluated. By way of example, FIG. 2 shows a measuring area 9 in which the opening 2 lies and / or which is arranged after the opening 2, that is, downstream of the opening 2. However, only a smaller measuring area 10, which is also schematically indicated in FIG. 2, is preferably relevant, which lies in particular in the area 6 of the vena contracta and in particular corresponds at least substantially to a cross section of the area 6. However, this represents only a preferred embodiment. Deviations from this are therefore possible.

For generating and for receiving or for detecting the ultrasonic waves 7, 8, preferably a so-called multi-array transducer 1 1 is used as a transducer or transmitter and receiver. The transducer 11 has a plurality of ultrasound generators, in particular piezoelectric elements arranged in a matrix, which are controllable in their phase and amplitude in such a way that the ultrasound waves are emitted as directional transmitted beams, in particular the direction of the transmitted beams and their width or cross section are electronically controllable. Accordingly, the receive direction and width or cross section of the received signals - ie the spatial resolution - controllable.

By means of the preferably provided multi-array transducer 11 or another suitable sound generator and receiver, in the proposed ultrasonic measuring method both the spatial position and the size-in particular cross-section and depth-of the measuring regions 9, 10 can be controlled and / or transmitted corresponding evaluation can be specified.

To carry out the ultrasound measurements and to control the transducer 11, the device 1 preferably has a color Doppler device 12, a matching device 13, a measuring device 14, a detection device 15, an evaluation device 16 and / or beyond the transducer 11 an associated display device 17, as indicated in Fig. 1.

The color Doppler device 12 measures according to the color Doppler method, in particular as explained above, the speed of the fluid. The measured speeds are color-coded. At speeds above the Nyquist speed, the named aliasing occurs. The color coded speeds are recorded as data record 18 and stored in particular. For this purpose, a memory or the like, not shown in FIG. 1, is preferably provided. The data record 18 thus represents a two-dimensional or in particular three-dimensional distribution of the color-coded speeds, in particular in the desired measuring range 10, possibly also in a larger measuring range 9.

The device 12 particularly preferably operates in real time and / or in accordance with the explained 3D color Doppler method.

The optional matching device 13 serves to adapt the color coding of the speeds of the data set 18 in order to ensure at most or all color-coded speeds in the measuring range of interest 10, ie in particular in the area of the vena contracta, that no color change or change occurs due to aliasing. This adjustment is made in particular by a corresponding zero line shift (see above explanation). Alternatively or additionally, a spread or shrinkage of the color range relative to the coded speed range can also take place.

Preferably, the recognition of a color change or change at the color-coded speeds within the relevant or interesting measuring range 10 takes place automatically in the data record 18. For this purpose, an unillustrated color sensor or the like can be used. However, it is alternatively, additionally or optionally also possible to make the adjustment - in particular zero-line shift - manually. The matching device 13 is then designed accordingly or can be omitted altogether.

The speeds modified with regard to their color coding are output, provided and / or stored by the adapter device 13, in particular as a modified data record 19.

Furthermore, the measuring device 14 is preferably provided for the separate and / or absolute measurement of a speed, in particular a mean or maximum speed in the measuring range 10. The measurement of the speed by the measuring device 14 or separately from the color Doppler method can, in particular, be carried out according to the continuous Doppler method or according to the method described in WO 2004/075754 A1, which is hereby introduced as a supplementary disclosure ,

The optional detection device 15 is used to detect aliasing in the aforementioned sense. In particular, it is detected how often the Nyquist speed of the color Doppler device 12 is exceeded by the speed measured by the measuring device 14, in particular the maximum or average velocity of the fluid in the measuring region 10.

The evaluation device 16 is designed to determine a measured value, in particular the volume flow and / or the flow volume, from the color-coded speeds of the adapted data record 19, that is to say after adaptation of the color coding by the adjusting device 13.

In particular, the determination of the measured value takes into account the aliasing determined by the detection device 15. This is preferably done in the embodiment in that the corresponding speeds are determined from the adapted data set 19 on the basis of the adapted color coding and a correction speed is added thereto. The correction speed results in the representation example from the product of the aliasing (more precisely, the aliasing factor or the number of color changes), as determined by the detection device 15, and the Nyquist speed of the color Doppler device 12 The resulting velocities represent a very good approximation of the actual velocities. These velocities are integrated over the cross-section or cross-sectional area to determine the volume flow of the fluid.

Alternatively, from the speeds of the data set 19 matched in their color coding, a first volume flow can first be determined by integration over the cross-sectional area. Next will be a second Volume flow determines, which takes into account the aliasing and is added to the first volume flow. The second volume flow is determined by the product aliasing times Nyquist speed, when the speed so determined is multiplied by or integrated across the cross-sectional area. The cross-sectional area can be determined and / or determined relatively easily by means of the color Doppler method or by means of the data set 19, in particular by means of the evaluation device 16. In particular, the desired cross-sectional area which covers the entire vena constracta is distinguished by an at least largely identical color due to the homogeneous and laminar flow in the region or within the vena contracta.

However, other methods are possible to determine and / or determine the cross-sectional area. In particular, a manual determination is possible. However, the manual setting is particularly preferably reduced to the setting of a desired cutting plane, preferably wherein in each case the calculated volume flow can also be displayed.

Alternatively, the speed detected separately by the measuring device 14 can also be used directly for scaling or fixing the color-coded speeds of the adapted data set 19. In this case, the determination of the aliasing and in particular the detection device 15 provided for it is not necessary.

In a further alternative, the aliasing may also be detected by counting the color changes or envelopes over, for example, a systole. In this case, in particular, the color change of different pixels, that is to say the speeds at different spatial points in the relevant measuring range 10, is detected. This can in turn be done by means of the detection unit 15 and / or using a color sensor, not shown, or the like.

The changes in volume flow over a cardiac cycle are recorded using several 3-D color Doppler data sets. In particular, the proposed determination of the measured values is repeated a number of times during a cardiac cycle or within a desired period, such as a systole. In the 3-D color Doppler data set 18, 19, a three-dimensional box-that is, a three-dimensional area-is preferably placed over the area of the vena contracta. Within the three-dimensional box, a cross-sectional plane may in particular be moved or determined manually (by a mouse control or the like) within which the flux quantification or determination of at least one measured value takes place. Thus, the desired measuring range 10 is determined. If necessary, the measuring area 10 is ultimately a two-dimensional, in particular flat surface.

By manually or automatically shifting the cutting plane in the 3-dimensional box, the corresponding volume flow can preferably be displayed directly.

By means of the display device 17, in particular a color image of the data set 19, that is the color-coded speeds with adapted color coding, can be displayed. Furthermore, the determined measured values are preferably also displayable. Both are preferably carried out in real time or continuously.

The determination of a speed by the measuring device 14 is particularly preferably carried out according to the continuous Doppler method. Fig. 3 shows schematically as an example an emerging Doppler spectrum - rate dependent on time - of a vena contracta in a mitral valve, ie the backflow of blood during two consecutive systoles. The Doppler spectrum shows no contours sharp curve, but at each point point a backscatter performance that varies with the proportions of different speed, as indicated in Fig. 3 by the dotted area and the drawn speed spectrum - distribution of shares at different speeds for a time - located. In the Doppler spectrum shown, not only is a speed of a certain point within the measuring range 9, 10 displayed, but the different speeds of all measuring points within the measuring range 9, 10 are taken into account, which can overlap at a certain time depending on the frequency occurring. Preferably, there is a continuous measurement of the speed, in particular the maximum speed, by the measuring device 14 according to the continuous Doppler method over a cardiac cycle, so that at the times of detection of the speeds by the color Doppler method, for example, the maximum flow rates based on the Doppler spectrum - in particular the line of maximum speed shown in Fig. 3 - can be detected at each time point of the determination of the measured values. This maximum speed is then preferably determined or output by the measuring device 14 and used for detecting the aliasing by the detection device 15 and / or for normalizing the color-coded speeds of the data set 18 or 19.

The Doppler spectrum resulting from the continuous Doppler method, as illustrated by way of example in FIG. 3, can alternatively or additionally also be used for determining the opening area of the opening 2 or the cross-sectional area, provided that the measuring area 9 or 10 is the opening 2 or opening area completely enveloped or covered. The integral of the power values over the speed or the speed spectrum at a time represents, namely, a measure of the opening area or cross-sectional area. It is possible to have an effective opening or cross-sectional area. Cross-sectional area to be determined, which corresponds to the effective in the vena contracta flow cross-sectional area and in particular by a factor of 0.65 to 0.85 is smaller than the geometric Öffhungsfläche the opening 2.

For details on the determination of the (maximum) speed by the continuous Doppler method and / or for determining the flow cross-sectional area, in particular taking into account power values in the Doppler spectrum, reference is made to WO 2004/075754 A1 or WO 00/51495 A1 , which are hereby incorporated in full as supplementary disclosures. However, as already stated, the flux cross-sectional area can also be determined from the color Doppler data or otherwise. The measuring device 14 or the continuous Doppler method preferred for separate measurement or evaluation can also be used to determine whether a vena contracta is present at all.

In order to determine whether there is a Doppler spectrum characteristic of a vena contracta, filtering is preferably carried out first. For example, all speed _values below a minimum _limit V _MΠM of, for example, 100 cm / s are disregarded and / or only speed values are taken into account which exhibit a bell-shaped or approximately normally distributed speed profile and / or above a minimum value of, for example, 20% -50% of the maximum value of respective spectrum. Subsequently, in the preferably filtered or otherwise suitably prepared spectra or values, it is preferably checked whether the average speed exceeds a minimum value or is maximal for all spectra or measuring ranges 9, 10, whether the width of the Doppler or velocity spectrum has a maximum width. is below the minimum value or is minimal for all spectra or measuring ranges 9, 10, whether the power or the power integral over the speed exceeds a minimum value or for all spectra or measuring ranges 9, 10 is maximum, whether the Dopplerspektrum one at least substantially continuous or continuous Line of maximum speed shows, as indicated in Fig. 3, and / or whether the speed spectrum at a time, in particular at maximum speed, as indicated in Fig. 3, at least substantially Gauss-distributed or normally distributed.

Only if at least one, two or, preferably, all of the aforementioned conditions are met is the proposed method or the proposed device 1 the occurrence of a vena contracta detected or at least provisionally accepted or an operator to the displayed, where necessary, in a the intended area of the presumed vena contracta performing image mode is switchable.

After determining the occurrence of a vena contracta, an ultrasound measurement for determining the measured values, as already explained above, can take place automatically or in response to a corresponding confirmation signal from an operator. The proposed device 1 and the proposed method thus preferably enable an automated localization and / or measurement of the measured values in the case of a dynamic and / or irregular opening 2 through which a fluid, such as blood 3, flows.

The proposed method and the proposed device 1 are characterized according to a development in that successively or simultaneously during a measurement period, the measured values for several separate openings 2 can be determined. It is thus possible, for example, for two separate openings 2, each with a Doppler spectrum characterizing a vena contracta, to be detected in the search mode and then measured either sequentially or simultaneously with determination of the measured values. The measured values can then be displayed to the operator, for example by means of the display device 17 shown schematically in FIG.

The proposed device 1 and the proposed method are universally applicable, with the optional automation in particular allows easy and safe operation and a quick examination or measurement.

In summary, or in other words, the present invention relates to a method and apparatus for noise suppression and / or visualization or production of color Doppler images at high flow velocities, in particular in the field of cardiology. By means of the continuous Doppler method, preferably the entire velocity profile within the volume to be examined, such as a vena contracta, is determined. So or otherwise, absolute speeds are determined. The relative velocity profiles provided by the color Doppler method, that is, the color-coded velocities, are determined by the absolute velocity. compared or scaled. Alternatively or additionally, this comparison or the scaling can also be carried out after conversion into volume flows. Alternatively or additionally, aliasing, as already described, is used to determine absolute velocities and / or absolute volume flows from the color-coded velocities.

In other words, the present invention can also be described as follows: The direct flux quantification in the case of partial valvular insufficiency by means of color Doppler echocardiography was previously impossible due to multiple color Doppler aliasing in the turbulent insufficiency jet. However, studies have shown that there is an at least substantially laminar flow in the vena contracta of the insufficiency jet with a narrow velocity spectrum and thus dealiasing for accurate determination of flow velocities should be possible. This assumption was verified using real-time 3D color Doppler data sets (RT3DE) in an in vitro flow model.

In the in vitro flow model, regurgitation jets were generated at flow rates between 5 to 60 ml / s through asymmetric openings of 0.2 to 0.6 cm ² . In the RT3DE data sets (IE33, Philips), the color Doppler cross-sectional area (QSF) was exactly represented by the vena contracta. The regurgitation flow without aliasing was calculated by automatic integration of color Doppler velocities across the QSF of the vena contracta (4D Echo View, TomTec, Munich), with aliasing prevented by maximum baseline shift to maximize the Nyquist spectrum. For the dealiasing, the number of aliasing runs was determined on the basis of the maximum CW Doppler speed. The regurgitation flux with aliasing was calculated from QSF x Nyquist velocity x number of aliasing runs. The total flow was the sum of the regurgitation flow without aliasing and aliasing.

The model showed that the RT3DE representation of the QSF of the vena contracta was possible for all flow sizes without color Doppler aliasing. The flow rates calculated from the RT3DE data sets showed an excellent correlation with the actual flow rates (r = 0.99) of the pilot plant with a mean error of 3.7 ± 2.5 ml (not significant in T-test). As a result, it has been shown that an accurate determination of the regurgitation flow at the vena contracta is possible by means of dialysis using RT3DE data sets. The new method can be directly implemented in existing RT3DE systems for determination of mitral regurgitation volume.

Claims

claims:

1. A method for ultrasonic measurement of a volume flow and / or flow volume of a fluid, in particular blood (3), by a particular dynamic and / or irregular opening (2) by means of a color Doppler device (12) at speeds above Nyquist speed, wherein by means of the color Doppler device (12) a two- or three-dimensional distribution of the velocity of the fluid in and / or after the opening (2) in a measuring range (9, 10), in particular in the region vena contracta, measured and recorded as a record (18) with color-coded velocities, wherein the color coding of the record (18) is adjusted so that at most or all color-coded velocities in the measuring range (9, 10) no color change takes place, the aliasing the color coding is determined, wherein the volume flow and / or the flow volume of the color-coded speeds of the adapted data set (19) taking into account the aliasing is determined or will be.

2. The method according to claim 1, characterized in that it is detected as an aliasing, how often the Nyquist speed is exceeded by a particular maximum or average speed in the measuring range (9, 10).

3. The method according to claim 2, characterized in that the maximum or average speed is determined separately and / or absolutely, in particular by means of a continuous Doppler method.

4. The method according to claim 2 or 3, characterized in that the same transducer is used for the color Doppler device (12) and for determining the maximum or average speed.

5. The method according to any one of the preceding claims, characterized in that the flowed through by the fluid cross-sectional area of the measuring range (9, 10) from the data set (18, 19) is determined.

6. The method according to any one of the preceding claims, characterized in that the volume flow from the integral of the color-coded speeds of the adapted data set (19) over the cross-sectional area of the measuring range is determined taking into account the aliasing.

7. The method according to any one of the preceding claims, characterized in that pulsed ultrasonic Doppler signals are used.

8. The method according to any one of the preceding claims, characterized in that a matrix array transducer (1 1) is used as a transducer and receiver.

9. The method according to any one of the preceding claims, characterized in that the matched in color coding speeds is displayed as a color image, the Öffhungsfläche, the volume flow, the flow volume and / or a dependent value or be.

10. Device (1) for the ultrasonic measurement of a volume flow and / or flow volume of a fluid, in particular blood (3), by a particular dynamic and / or irregular opening (2), with a color Doppler device (12) a two- or three-dimensional distribution of the velocity of the fluid in and / or after the opening (2) in a measuring range (9, 10), in particular in the region of a vena contrac- ta to measure and as a data set (18) with color-coded speeds capture, with a matching device (13) for adjusting the zero line and / or spreading of the color coding of the data set (18), so that at the color-coded speeds in the measuring range (9, 10) no color change occurs, with a measuring device (14) for separate and or absolute measurement of a particular maximum or average velocity of the fluid in the measuring range (9, 10), with an acquisition device (15) for detecting as aliasing how often the Nyquist speed of the color Doppler device (12) is exceeded by the speed measured in the measuring range (9, 10) by the measuring device (14), with an evaluation device ( 16) for determining the volume flow and / or flow volume from the matched in their color coding speeds of the adapted data set (19), taking into account the aliasing.

11. The device according to claim 10, characterized in that the measuring device (14) operates according to the continuous Doppler method.

12. The apparatus of claim 10 or 11, characterized in that the color Doppler device (12) and the measuring device (14) use the same transducer.

13. Device according to one of claims 10 to 12, characterized marked, that the device (1) comprises a matrix array transducer (11) for generating and detecting ultrasonic signals (7, 8) or as a transducer.

14. Device according to one of claims 10 to 13, characterized marked, that the device (1) comprises a display device (17) for displaying the adapted in the color coding speeds as a color image, the volume flow, the flow volume and / or a value proportional thereto , in particular in real time.

15. Device according to one of claims 10 to 14, characterized in that the device (1) for carrying out a method according to one of claims 1 to 9 is formed.

16. Use of a color Doppler data set (18, 19) with color-coded speeds of a color Doppler device for determining a volume flow and / or flow volume of a fluid, in particular blood (3), by a particularly dynamic and / or irregular opening ( 2) wherein the zero line of the color coding of the speeds is adjusted so that at most or all color-coded speeds in a spatial measuring range, in particular in the area of a vena contracta, no color change takes place, and / or wherein the volume flow and / or the flow volume of the color-coded speeds the adjusted data set is determined in consideration of the absolute value of at least one of the speeds and / or taking into account the aliasing and the Nyquist speed of the color Doppler device.