Device and method for measuring elasticity of a human or animal organ and for two- or three-dimensional representation thereof

Translation of description of equivalent WO 2004021888 A2

DEVICE AND METHOD FOR MEASURING THE ELASTICITY

ORGAN HUMAN OR ANIMAL AND AN INSTITUTION

REPRESENTATION TO TWO OR THREE DIMENSIONS OF THIS

ELASTICITY

The present invention relates to a device and method for measuring the elasticity of a human or animal organ, or more generally all viscoelastic media having an ultrasonic signal after ultrasonic illumination and subsequent determination of a representation of two or three dimensions of elasticity. It applies in particular, but not exclusively, for measuring the elasticity of a human breast, the advantage of this technique is that the pathological tissue is often connected to their elasticity.

Known in the prior art French patent application FR 2733142, which discloses an elasticity measuring device providing a measurement in two dimensions but also adapted to perform a measurement in three dimensions. However, this device does not have a scanning means adapted to perform the scanning of the at least two perpendicular directions strips.

US Patents Also known US 6176827, US 5099848, US 2002/010398, US 6277074, US 5474070, which disclose all solutions to measure only a two-dimensional, sometimes with a fixed bridge (see US 6176827) At present, there exist on the market ultrasonic measuring devices elasticity for displaying said measurement in two or three dimensions.

Furthermore, concerning the measurement of elasticity in two dimensions known article "Shear Modulus Imaging with 2D Transient Elastography" by Sandrin, L. Tanter, M., Catheline, S., and Fink, M., Ultrasound . Ferroelectr. Freq. Control., Vol. 49 (4), pp. 426-435 (2002) describe a technique of measuring the elasticity and the two-dimensional representation of this measurement. The resolution of the inverse problem, that is to say consisting of back to the parameters that describe the viscoelastic medium which is to be measured, here is flawed because moving is not known in all three spatial directions . According to the computational algorithms related to measurements made by the device presented in this article, operators will be forced to make assumptions to solve the elasticity calculations, but experience has shown that these assumptions are rarely justified.

Also known international patent application No. W0 0,070,362 which describes a system using 1 'magnetic resonance elastography (MRE), in which a viscoelastic area

(Such as human breast) is excited by mechanical waves. The object of this invention is based on the assumption that the results of measurements by ERM solutions are independent of the time of partial differential equations that describe accurately the behavior of mechanical waves in a material viscoelastic (including longitudinal waves and in a reflective environment). For this, the Young's modulus contained in these equations can be calculated. In addition, it is proposed here to use (predominantly) of longitudinal waves, these being capable of penetrating the human breast, which is not the case of transverse waves.

In the device of this patent application, obtaining the yield map require much time. Furthermore, the implementation cost of this device is very high.

In addition, it is clear that measuring the elasticity of larger dimensions is a considerable advantage, this significant improvement in the state of the art is obtained by the device according to the invention.

The prior art is also constituted by the international patent application No. FR 9903157 which describes an imaging method to observe the propagation of a pulse wave low frequency shear simultaneously into a plurality of points of a viscoelastic scattering medium. To this end, it emits, in this device, ultrarapid rate of ultrasonic compression waves which allow to obtain a succession of images of the medium, and then treated in deferred time the images obtained by cross-correlation, to determine at each point each frame the movements of the medium during the propagation of the shear wave.

This invention is not satisfactory because it requires considering two hypotheses: the second derivative of displacement is considered null in the direction orthogonal to the plane, the medium is assumed to be perfectly incompressible.

The invention therefore more particularly to remedy the disadvantages of the prior art systems. It proposes for this purpose a device for measuring the elasticity of a human or animal organ, particularly breast, or more generally all viscoelastic media having an ultrasonic signal after ultrasonic illumination and consecutive establishment of a representation in two or three dimensions of elasticity, comprising at least one ultrasonic bar (1) comprising a plurality of transducers (12) or the like, a drive means capable of generating and outputting a low frequency biasing, directly or indirectly a means for acquiring ultrasonic signals, means of control and data processing, such as a computer, characterized in that it comprises scanning means adapted to perform scanning of the said strip (1) to one-dimensional (1D) or two-dimensional

(2D) in two perpendicular directions, and thereby respectively obtain a representation of the extent of elasticity in two (2D) or three dimensional (3D).

With these features, the invention therefore to provide a device which provides a mapping of the middle of elasticity measured in two or three dimensions, with a relatively simple and inexpensive system relative to existing solutions. Advantageously, the ultrasonic bar include a plurality of transducers for acquiring ultrasound signals.

In a possibility offered by the invention, the average excitation consist of a mechanical vibration that can be transversal, longitudinal or more generally a mixture of both.

Advantageously, the drive means may consist of one or more transducers of yperthermie because the temperature rise generates displacements on the ultrasonic image, with either the (s) transducer (s) (s) used for the acquisition ultrasonic signals or one or more transducers arranged around the viscoelastic medium. Similarly, the energizing means may also consist of internal movements of the human or animal body, such as for example the heart beats.

According to another possibility offered by the invention, the drive means consist of a remote palpation using the pressure of radiation, either with the (s) transducer (s) (s) used for the acquisition of the ultrasonic signals is one or more transducers arranged around the viscoelastic medium.

Advantageously, the device according to the invention will be controlled by at least one control means, for example a computer, a microcomputer or a CPU. Advantageously, the ultrasonic bar will be a bar or a star 1.5 D transducer for focusing in a plurality of different points of elevation; in this case, the scanning being carried out by ultrasonic focusing.

It should be recalled here that a 1.5 D bar and called in the technical field of the invention is a strip capable not only to focus on a plane but also in elevation relative to the plan, in the example according to the horizontal plane parallel to the preceding and slightly offset.

It is also recalled, in order to facilitate understanding of the invention, a strip echographic 0 D emits a linear dimension x, a strip 1 D emits according to a two-dimensional x, y plane and finally that a bar 2 D, usually constituted by a plurality of ultrasonic transducers square distributed in a matrix 2 D gives emitting ultrasound in a volume in the three dimensions x, y and z.

According to one embodiment of the invention, the space between the ultrasonic bar and the above viscoelastic medium will be formed at least in part by water or any other element capable of ensuring the free passage of ultrasound waves.

Advantageously, the group consisting of ultrasonic transducers and their on-board electronics will be connected to the control means and Treatment with a digital connection at high speed, eg LVDS kind.

According to one embodiment of the invention, the device of the invention include two ultrasonic bars.

According to an embodiment of the device of the invention, the two bars are disposed in an airtight container filled with a liquid, for example water.

Advantageously, the airtight container will be connected to a rotating means adapted to rotate said container.

In a possibility offered by the invention, the sealed container may include a plurality of holes in which are respectively introduced a mechanical vibrator and / or an ultrasound transducer.

Advantageously, the holes on or in the sealed housing will be located at 90 ° (degrees) from each other or one another.

According to another embodiment of the invention, the device according to the invention will comprise three modules respectively adapted to measure tissue velocities in the directions y, x and z.

The invention also relates to a method for measuring the elasticity of a human or animal organ, particularly breast, or more generally all viscoelastic media having an ultrasonic signal after ultrasonic illumination and subsequent establishment of a representation in two or three dimensions of elasticity, comprising at least one ultrasonic bar (1), or the like, a drive means adapted to generate displacements low frequencies, means for acquiring ultrasonic signals, means of control and data processing, such as a computer, a scanning means adapted to perform scanning of the said strip (1) to a dimension ( 1D) or two dimensional (2D), thereby respectively obtain a representation of the extent of elasticity in two (2D) or three dimensional (3D), characterized in that it comprises the following steps: - generating a request , or signal, low frequency and acquisition of ultrasonic signals, displacement of the bar through the scanning means in two perpendicular directions, calculation of the ultrasound images, calculating tissular speeds, data inversion of retrieving the parameters that describe said viscoelastic medium .

Advantageously, the step of displacement of the strip will be repeated as many times necessary for the acquisition of all the ultrasound data before moving to the calculation step of the ultrasound images.

It should be noted that the step of acquiring ultrasound data also helps develop data necessary to obtain a conventional ultrasound image, that is to say using a "beamforming" classic. Indeed, or the thus obtained images are relevant information in 2D or 3D on the morphology of the organ studied, this information is quite complementary to the parameter of elasticity.

Advantageously, during the step of calculating the tissue velocities, the second of the longitudinal component derived from this speed along the three orthogonal directions in space can be measured.

Similarly, during the step of calculating the tissue velocities, the spatial derivatives of the three components in the three directions of space, said speed can be measured.

Embodiments of the invention will be described hereinafter, by way of nonlimiting example, with reference to the accompanying drawings in which:

Figure 1 illustrates the movement of a echographic bar of the device according to the invention with a simple mechanical scanning means;

2 illustrates the displacement of an echographic bar of the device according to the invention provided with a double mechanical scanning means; Figure 3 illustrates the operation of a strip 1.5 D of the device according to the invention provided with a by ultrasonic focusing elevation scanning means;

4 illustrates the device according to the invention provided with a strip 1.5 or 1.75 D, capable of focusing in elevation;

- Figure 5 shows the device according to the invention provided with a transducer star wherein the transducers are spatially distributed;

Figure 6 shows the device according to the invention are measuring the elasticity of the breast of a patient;

7 schematically illustrates an embodiment of the device according to the invention.

The attached figures do not represent the complete device. This device comprises the usual elements for taking measurements of elasticity of a human or animal organ, that is to say in particular at least one web, or probe, ultrasound having a plurality of transducers, an electronic equipment capable of providing acquiring ultrasonic signals, means of control and data processing such as a computer or the like and a drive means adapted to generate low-frequency movements.

The invention relates to the use of a mechanical scanning means which ensures scanning the aforesaid ultrasonic bar. This allows, thanks to the process of the invention, to measure parameters which are not accessible with the devices of the prior art, including that described in Patent No. FR 9903157. The parameters thus obtained are the second derivative of displacement following the elevation, that is to say the direction perpendicular to the image plane, and the two missing components displaceme vector.

In the following, we chose to illustrate invention, taking as a human or animal organ, breast but any other organ, ideally static, may be a measure of elasticity thanks to the device and the method according to the present invention provided, of course, to present an ultrasonic signal after it has been illuminated using ultrasonic signals. However, if the internal movements of the body can be a low usable frequency solicitation for the process, it is preferable that the body is still not to disturb the measurement.

The method according to the invention performs the following steps in the following chronological order:

1. generating a solicitation or signal, low frequency,

2. acquiring ultrasound data,

3. movement of the strip through the scanning means,

4. calculation of the ultrasound images,

5. calculating tissular speeds, also called displacement between successive images, 6. optionally calculation tissue strain rate,

7. Finally, data inversion, which retrieves the parameters of the measured medium.

It should be noted that the calculation steps, namely steps 4 through 6, can begin as soon as the ultrasonic bar scans the viscoelastic medium, that is to say that these steps take place ideally during movement of said bar.

During generation stage of the solicitation, or signal, low frequency, low frequency signal is transmitted using preferably excitement just after the start of ultrasonic acquisitions. This signal has a frequency, f, of between 5 Hz and 1000 Hz. The low frequency vibration causes the propagation in tissue viscoelastic medium low-frequency elastic waves whose propagation depends on the elasticity of the medium.

The various means used to generate low frequency displacements may consist of a mechanical vibration produced by a vibrator can be in particular one or more vibrating plates 20, piston (s) and / or rod (s). Similarly, the excitation means capable of generating a shear wave will consist of a remote palpation using radiation pressure or with the (s) transducer (s) (s) used for signal acquisition ultrasonic, or one or more transducers arranged around the object to be imaged. JL J

During the step of acquiring ultrasound data, N ultrasonic acquisitions are made at a rate 1 / T is typically between 100 Hz and 100,000 Hz. The acquisition of the ultrasound data is done by emitting the ultrasonic transducers with a pulse brief ultrasonic which is reflected by the particles contained in the medium. The ultrasonic signal, called "speckle" is recorded by the same ultrasonic transducers on a duration of between 1 s and 10 ms. This operation is repeated N number of times at the rate 1 / T.

Then comes one step of moving the echographic or ultrasonic bar. At this level, the scanning of moving said strip will be achieved in three different ways depending on the number and type of used ultrasonic bar.

Thus, the device according to the invention may especially be equipped with: one-way ultrasonic bar 1, two ultrasonic bars 5, 6 or a bar then moved along two axes - an ultrasonic bar type 1.5

D 9.

In the case of one-way ultrasonic bar 1, shown in Figure 1, the echographic bar 1 is moved a distance of between 10 microns and 10 mm. at least one carries a sweep in a direction. For example, it scans in the direction z, constituted by the plane 2, by moving .DELTA.z constituted in the figure by the two planes 3 and 4.

In the case of two ultrasonic bars 5 and 6, shown in Figure 2, or equivalent to a strip moved along two axes 7 and 8, two webs 5 and 6 are used (a single or successively). This scan provides access to all components of the vector speed tissue.

In the case of an ultrasonic bar type 1.5 D 9, represented in Figure 3, the mechanical scanning is avoided, the result being the same with a star transducer; these two elements for focussing at three different points of elevation. In the case of a 1.5D array 9, the displacement along z is obtained by modifying the focusing laws so as to change the elevation of the image plane.

During the step of calculation of the ultrasound images, the ultrasound images are constructed using a delay-sum algorithm such as that described in Patent No. FR 9903157 previously mentioned or other types of "beamforming" fast as e.g. the art in the space of spatial frequencies (see Article Lu, J., "2D and 3D high frame rate Imaging with Limited diffraction Beams", IEEE Trans. Ultrason. Ferroelectr. Freq. Contr., vol. 44, No. 4, 1997.).

During one step of calculating tissular speeds, also called displacement between successive images, tissue velocity or displacement between two successive ultrasound shots, but not 3

necessarily consecutive, are measured either by cross-correlation, described in Patent No. FR 9903157, by Doppler or by autocorrelation, described notably in section C of Kasai, K. Namekawa, Koyano A. and R. Omoto "Real-time two-dimensional blood flow imaging using an autocorrelation technical ", IEEE Trans. Sonics Ultrasound., Vol. 35, pp. 458-464 (1985), and more generally by any other technique for measuring displacement.

Using a simple mechanical scanning shown in Figure 1, accesses to at least the following x component of the tissue velocity V_x in each point of the medium located in the imaged area. Using an algorithm of the type described in the articles of Konofagou, EE, Ophir, J., "A new method for estimating elastographic and imaging of lateral displacements, lateral strains, corrected axial strains and Poisson's ratios in tissues" Ul trasound in Med. & Biol. 24, No. 8, pp. 1183-1199 (1998) and Tanter, M., Bercoff, J., Sandrin, L. Fink, M., "Ultrafast imaging compound for 2D motion vector estimation: application to transient Elastography" Trason Ul. Ferroelectr. Freq. Control. , It can also access the lateral component of the tissue velocity V_there. Using double mechanical scanning as shown in Figure 2, it accesses the three components of the tissue velocity: the bar 6 can measure V_x and V_there and the strip 5 can measure V_there and V_z . The accuracy of the estimate of V_there is increased by calculating the half-sum of the estimates with the two webs 5 and 6. During the optional step of calculating tissue strain rates, tissue strain rate is obtained by differentiating V_z, Also noted v (z, t) in the direction of the component considered, here in relation to the depth:

<img id="imgf000018_0001" he="5" wi="4" file="imgf000018_0001.tif" img-format="tif" img-content="drawing" orientation="portrait" inline="no" /> with i = x, y or z

The data inversion step is to back up or recover the parameters that describe the viscoelastic medium. If we consider the linear and isotropic medium, these parameters are two in number. One can choose the shear modulus μ and λ the compression module. In practice in the soft tissue λ is of the order of GPa and varies little. μ is of the order of kPa. The elasticity or Young's modulus is equal to a first approximation to 3μ. Thus, it should determine the shear modulus μ which is the most significant parameter in the measured viscoelastic medium.

In the case of a simple mechanical scanning, that is to say comprising a unidirectional array

1, all components of the tissue velocity vector is not known. The data may be inverted using the following equation:

<img id="imgf000018_0002" he="17" wi="68" file="imgf000018_0002.tif" img-format="tif" img-content="drawing" orientation="portrait" inline="no" />

To put the above equation, it was necessary to make the assumption that the waves 1 / browsing elastic medium are purely shear wave. In practice, this assumption is because t f ausse from are not fully incompressible, which means that any shear wave s' necessarily accompanied by a compression wave.

The desired parameter, μ (x, y, z) is obtained in discrete i sant this ion Eq. In elastography, we generally have one of three coordinates v_xv_there or v_z . Suppose it is v_x. To discretize this equation the second derivatives must be calculated in three directions and time:

<img id="imgf000019_0001" he="54" wi="104" file="imgf000019_0001.tif" img-format="tif" img-content="drawing" orientation="portrait" inline="no" /> m. .DELTA.z). We must therefore not only know the displacement v_x in the image plane, but also the know around the image plane to estimate the second derivative perpendicular to the image plane: dv²/ dz². In French Patent No. FR 9903157 and publications transient elastography, the second derivative perpendicular to the image plane is removed from the equation because it can be measured experimentally. Indeed, v is measured in the plane (x, y), only v (x, y) is known. dv²/ dz² can not be determined. A known hypothesis is to ask: at

d² υ

Dz = 0

The equation simplifies to

<img id="imgf000020_0001" he="13" wi="45" file="imgf000020_0001.tif" img-format="tif" img-content="drawing" orientation="portrait" inline="no" />

or ι = x, y or z. It can be solved without knowing the movements in the planes located on either side of the plane of the image z + and z-.DELTA.z .DELTA.z.

The null hypothesis of the second derivative perpendicular to the image plane is particularly restrictive and does not solve the inverse problem under good conditions since it is highly unlikely that dv² / dz² is zero. Thanks to the device according to the invention, the missing derivative can be obtained.

It is thus envisaged two solutions to measure v (x, y, z) and calculate dv²/ dz² Either using a web 1.5 D 9 or star transducer for focusing at three different points of elevation or reproducing three times the acquisition by successively moving the bar in z-.DELTA.z, z and z + with .DELTA.z .DELTA.z chosen judiciously so as to be close resolutions obtained by x and y (.DELTA.z = Ax and .delta.Y).

When using a strip 1.5 or 1.75 D 9

D, shown in Figure 4, it can produce images 10 in three planes of the image and calculate the movements in these three planes eg z-.DELTA.z, z and z + .DELTA.z. the maximum rate is however reduced here by a factor of 3. It can also use a star transducer 11 in which the transducers 12 are spatially distributed as shown in Figure 5.

In the second solution, of reproducing three times the acquisition by successively moving the bar in z-.DELTA.z, z and z + .DELTA.z, it should be noted that it is important to ensure that the medium viscoelasticity measure does not have moved between two acquisitions and that the applied low frequency input is synchronized to each elevational position.

In the case of a dual mechanical scanning, that is to say either with two webs 5, 6 is a strip moving along two axes, all components of the tissue velocity vector are known. A more general case (compressible medium) is to use the Navier who wrote:

<img id="imgf000021_0001" he="13" wi="57" file="imgf000021_0001.tif" img-format="tif" img-content="drawing" orientation="portrait" inline="no" />

We can af finer this through the following equation:

<img id="imgf000021_0002" he="15" wi="77" file="imgf000021_0002.tif" img-format="tif" img-content="drawing" orientation="portrait" inline="no" /> where v_x = v_xv₂ = v_therev₃ = v₂ Xi x, x₂ And x = y = z. then we have a system of three equations and two unknowns: λ (x, y, z) and μ (x, y, z) as the density p varies very little in the tissues.

With the following equation on it, you understand why neglect tissue velocities associated with compression waves is a source of error. Certainly tissue velocities associated with compression waves are small compared to those generated by the shear wave, but their contribution can not be overlooked because the coefficient λ factor is great before the end of compression. The discretization of this equation can be achieved if all three components of tissue velocity vector are known. Indeed this equation involves coupling between changes in tissue velocities in all directions.

The invention proposes using a mounting device or as shown in Figure 6. This device allows to measure the three components of the tissular speed vector in the organ studied by successively scanning said medium in three different axes 13, 14 and 15 . the strip 16 can measure tissue velocities in the y direction denoted u_there, The bar 17 for measuring u_x and the bar

18 for measuring u_z . The use of an algorithm for measuring the transverse displacements can help reduce the number of scanning areas from three to two by eliminating for example the bar 18. The displacement u₂ would be determined both with the bar 16 and the bar 17 which would make a u mean_z= (U_2B1 + u_ZB2) / 2. A synchronization system moves the transducer 12 between two acquisitions, an acquisition comprising generating elastic shear wave and acquisition of the ultrasonic signals. The displacement system can be realized for example with a stepping motor or an electrodynamic actuator.

This acquisition sequence must be repeated as many times as there are plane in the image. Using three webs 16, 17, 18 128 each taking different positions, the system requires 384 separate acquisition sequences. The medium studied can then be segmented into 128³ 19 cubic voxels. The rate of acquisition of the ultrasonic signals is between 100 and 100 000 shots per second.

Assuming that in the analysis medium, the shear wave propagates 1 m / s and that the major dimension of this medium is 12.8 cm and the voxels have to 1mm size³. The propagation of the shear wave in such an environment and a length of 12.8 cm lasts 128 ms. For a typical rate of 1 000 shots per second, 128 ultrasound shots must be made to follow the propagation of the shear wave. We can estimate that after 150 ms acquisition ends.

Suppose the ultrasonic device moves after 500 ms and a second set of ultrasound shots 128 is achieved. If one uses three ultrasonic bars to access the three components of the displacement, it will take about 3 minutes

(384 × 500 ms) to acquire all of the data necessary to solve the inverse problem. The measuring time can be reduced by interlacing the ultrasonic shots, 128 shots are therefore needed one minute of acquisition.

If scanning, one of the difficulties is to keep a good coupling between the transducer and the medium studied for the duration of the scan. In the case where the medium surface is plane, the scanning can be performed using an ultrasonic coupling, for example a water-based gel. When this is not possible or when the surface of the medium is "rugged" we suggest to immerse the viscoelastic medium in water. This scenario is shown in Figure 6 where the breast 21 of a patient is immersed in a tank 22, parallelepiped having transparent windows ultrasonic filled with water.

As we have seen, the device of the invention requires at least one echographic bar. It also requires electronic equipment for ultrasonic acquisition consists of transmitters and ultrasonic receivers, digital-analog converters and analog-digital, memories, rows of digital and analog transmission, etc. To this dedicated to electronic scanning ultrasonic signals, usually adding a processing unit which can be for example a PC computer associated with a user interface. The elements mentioned in this paragraph are not represented in the different figures but are well known to the skilled person. 3 .-

The techniques of ultrafast ultrasound imaging will typically use a limited number of ultrasonic emissions to illuminate the entire environment to be imaged. They therefore have the drawback of sending less energy in the middle a standard echographic system. Therefore the signal to noise ratio drops and the dynamics of the ultrasound image decreases, which results in deterioration of raw ultrasound data and are reflected in the chain of algorithms to degrade in terms of elasticity measures of sensitivity, resolution etc.

To overcome this drawback, the device of the invention loads a part of the aforementioned electronic equipment near, that is to say, typically at a distance less than 50 centimeters, the ultrasonic bar, resulting in: "increasing the sensitivity of the system,

• increasing the energy transmitted,

• simpli ication connections between the motorized sensor part (+ bar board electronic equipment) and the data processing unit (PC or embedded PC card or DSP or processor etc.), • increased noise immunity.

These changes result in decreased mobility of the bar that is not compatible with standard use ultrasound because ultrasound modules are light and handy. It is important to note that in the case before us, the mobility of the bar is anyway limited by the stroke of scanning. The weight __4

of the strip is less important because the bar is not manipulated. It is motorized.

In a possibility offered by the invention, the device proposes to place nearby, is typically less than 50, of the strip the analog portion of transmission and reception, that is to say the transmitting amplifiers and reception, keeping a analogue signal transmission means levels between the sensor part and the processing unit. In this way, the path of the analog of strong emission signals (after amplification) and that of weak reception signals (before amplification) are reduced, so the reception sensitivity is increased and the energy transfer enhanced emission .

According to another possibility offered by the invention, the device offers also place nearby, still typically less than 50 cm

(Centimeter) strip of the analog-digital converters (ADCs) and digital-to-analog

(CNA) (for transmission and reception) and connect the sensor part and the processing unit by a very high-speed digital link (LVDS type for example). The structure of the device according to the invention thus produced has the following improvements: • the signal to noise ratio is increased by housing all the analog portion at the source. Strong analog signals (transmitters) and weak (receivers) are concentrated at the sensor and no longer traverse the distance between the processing unit and the sensor part. Δ

• The received noise and noise are reduced because the connection between the processing unit and the sensor portion is purely digital.

The connection between the control means / processing and the sensor part is simplified in terms of number of son.

Assuming that an operator uses an array of 128 elements, converters (DACs and ADCs) 8-bit 50 MHz for transmission and reception. If transmitter and receiver are separated in time and that all channels are active, the digital data transfer rate is 128 X 8 X 50 = 51.2 Gbps (Giga bits per second). It currently only have 17 high-speed digital connections to 3.125 Gbps to deliver data in real time. By comparison analog solution would require 128 two-wire connections.

In Figure 7, the device according to the invention is represented in a new assembly. In this variant of the device, two ultrasound probes 23 and 24 are used, and are immersed in a sealed container 26, filled with water or other suitable liquid.

The container or sealed housing is rotatable, for example, a quarter turn so that the probe 23 can not only scan in the X direction but also in the direction Z. The ultrasound probe 24 scans only the Z-direction . the acquisition of the ultrasonic signals, therefore, involves three stages: - Scanning along the X and Z with the two probes 23 and 24, rotation of the airtight container or box 26, for example, a quarter turn or 90 degrees,

- Scanning the Z-direction through the probe 23.

For the acquisitions, mechanical vibrators 25, inserted into holes present on the periphery or circumference of the hermetic container 26 can be used to generate low frequency stress. One of the two mechanical vibrators, or two mechanical vibrators, shown in Figure 7 may / can be replaced (s) by a probe of hyperthermia and / or an ultrasonic transducer used in remote palpation mode. In the example chosen to illustrate the invention, the two holes in or on the hermetic housing 26 are located at 90 degrees to one another, that is to say that the linear mechanical vibrators are arranged perpendicular relative to each other, so that even after a rotation through a quarter turn (90 °) of the container 26, the mechanical vibrators always extend in the same directions, that is, -dire the same as prior rights.

The invention is described in the above as an example. It is understood that the skilled person is able to produce different variants of the device and method for measuring the elasticity of a human or animal organ and the subsequent establishment of a representation in two or three Δ I dimensions of elasticity, particularly regarding the disposition or arrangement of the various elements constituting the said device or order as well as the importance of the steps of said method without departing from the scope of the patent.