Ultrasonic elastography treatment to characterize a medium of interest

Abstract

Ultrasonic elastography processing to characterize a medium of interest The disclosure relates to an ultrasonic elastography processing method and a corresponding device (20).The method comprises: obtaining initial data (DT1) representative of an ultrasonic response (16) of a medium of interest (4) to ultrasonic pulses (8) focused in the medium and to sounding waves (14) emitted sequentially according to distinct values ​​(VL) of at least one parameter (PR) of the sounding waves; generating, from the initial data respectively for each said parameter value (VL), second data representative of shear wave propagation in the medium; estimating, from the second data associated with each said parameter value (VL), an individual velocity (VI) representative of the shear wave propagation speed for said value respectively; and estimating at least one velocity (VC), called the compound velocity, of the shear waves by a combination of the individual velocities. Figure for the abstract: Figure 6.

Description

Title of the invention: Ultrasonic elastography treatment for characterizing a medium of interest Previous technique

[0001] This disclosure relates to examinations or scans, or observations, using ultrasound-type waves to characterize a region of interest and more particularly to the processing of data characterizing a response of such a medium of interest to an ultrasound scan in elastography mode.

[0002] Ultrasonic devices now have numerous applications, particularly in the fields of acoustics, materials science, medical and veterinary imaging, and biomedicine. Such devices are commonly used, for example, to characterize and observe internal structures of the human body.

[0003] The principle of an ultrasound scan is based on the emission, by a probe, of ultrasonic waves that pass through a region of interest, for example, the tissues of a body being examined. These waves are reflected when they encounter specific features, such as interfaces between different types of tissue. The reflected waves are then captured back by the probe or another device and converted into electrical signals. Processing means then analyze the ultrasonic response of the medium of interest using these signals to generate data characterizing the medium. Thus, from a series of insonifications of the medium using ultrasonic transducers, it is possible to receive and analyze the echoes backscattered by that same medium and to deduce characteristics of the medium under study.

[0004] In ultrasound imaging, for example, also called echography, the processing of these ultrasonic echoes makes it possible to generate various information relating to the medium studied, such as an image or series of images according to an appropriate mode, such as a B mode (that is to say a two-dimensional mode of intensity of the received signal), a Doppler mode or a shear wave elastography mode also called SWE for "ShearWave® Elastography".

[0005] Ultrasonic elastography is an ultrasonic characterization technique used to estimate the elasticity or stiffness of a medium of interest being examined. It works by focusing ultrasonic pulses into a specific area of ​​a region of interest, such as the body of a subject, which generates shear waves propagating laterally in said region, for example through the tissues of the body being examined. To characterize these shear waves, probing waves are also emitted, allowing the propagation of these shear waves to be tracked in real time or Near real-time. By analyzing the propagation speed of these shear waves, it is indeed possible to estimate the stiffness of the medium of interest. Stiffer tissues or areas allow shear waves to propagate more rapidly, while softer tissues (or areas) slow their propagation or exhibit a slower rate of wave propagation. Using this technique, a map of the elasticity of the tissues in the examined medium can be created, particularly useful for detecting certain medical conditions, such as abnormalities like tumors or fibroses, which often exhibit a different stiffness than healthy tissues. This technique also allows for the indication of a tissue stiffness level, which in medicine can be compared to a practitioner's palpation.

[0006] Currently, ultrasonic systems operating in ultrasonic elastography mode exhibit performance that is not entirely satisfactory, particularly in terms of the accuracy and reliability of estimating the velocity of shear waves propagating in a medium of interest. This limits the ability of these systems to characterize the medium under consideration. These limitations can lead to errors or inaccuracies in the assessment of tissue stiffness, and may even degrade image quality in imaging applications, particularly in medical imaging. A poor estimation of shear wave velocity can lead to an inaccurate interpretation of tissue stiffness or of all or part of the examined areas, which notably limits the use of ultrasonic elastography in medical applications. Statement of Disclosure

[0007] One of the purposes of this disclosure is to resolve at least one of the problems or deficiencies described above.

[0008] In particular, one object of the present disclosure is to process ultrasonic elastography data more efficiently to enable an accurate and reliable estimation of the speed of shear waves propagating in a medium of interest.

[0009] In particular, an object of the present disclosure is to process ultrasonic data representative of an ultrasonic response, of a medium of interest, to ultrasonic pulses focused in said medium in combination with sounding waves of which at least one parameter is varied over time.

[0010] To this end, according to a first aspect, the present disclosure relates to an ultrasonic elastography processing method, also referred to as a processing method, the method comprising: a) obtaining initial representative data on the ultrasonic response of a medium of interest to ultrasonic pulses focused into said medium by combination with sounding waves emitted sequentially in said medium according to distinct values ​​of at least one parameter of said sounding waves; b) generation, from the first data respectively for each value of said at least one parameter, of second data representative of a propagation of shear waves in the medium of interest under the effect of ultrasonic pulses; (c) estimation, from the second set of data associated with each value of said at least one parameter, of an individual speed representative of the speed of shear wave propagation for said value respectively; and d) estimation of at least one speed, called compound speed, of the shear waves by a combination of the individual speeds.

[0011] The process according to the disclosure may include other features which may be taken separately or in combination, including among the following embodiments which are presented by way of illustration only and may be combined or associated unless otherwise stipulated.

[0012] According to one example, said at least one parameter of the sounding waves comprises at least one of: - an emission angle at which the sounding waves are emitted in the direction of the medium of interest; and - a frequency at which sounding waves are emitted towards the medium of interest.

[0013] According to one example, sounding waves include ultrasonic plane waves used to sound the medium of interest.

[0014] According to one example, the process comprises, prior to obtaining a): el) formation of shear waves in the medium of interest by focusing ultrasonic pulses; and e2) emission, in the medium of interest, of sounding waves configured sequentially according to distinct values ​​of said at least one parameter to detect the ultrasonic response of the medium of interest for each said value.

[0015] According to one example, the second data generated in b) define, for each value of said at least one parameter, a sequence of images representative of the propagation of shear waves caused by ultrasonic pulses in the medium of interest.

[0016] According to one example, during estimation d), the combination of individual speeds is determined by calculating an average of the individual speeds to estimate said at least one composite speed.

[0017] According to one example, estimate d) includes: - weight assignment, in association with individual speeds, based on at least one characteristic of the second set of data generated respectively for each value of said at least one parameter; and - estimation of said at least one compound speed by calculating the average by weighting the individual speeds according to said associated weights.

[0018] According to one example, estimate d) includes: - determination of spatial variances characterizing respectively the second data points associated with each value of said at least one parameter; and - determination, based on spatial variances, of confidence scores associated respectively with individual speeds, the weight assigned to each individual speed being a function of the associated confidence score.

[0019] According to one example, estimate d) includes: - if a confidence score associated with second data corresponding to a value of said at least one parameter does not satisfy at least one quality criterion, the weight assigned to the individual speed associated with said value is zero so as to exclude said individual speed from the estimation d) of said at least one compound speed.

[0020] According to one example, the method further comprises: f) estimation, from said at least one compound speed, of a hardness of the medium of interest.

[0021] According to one example, during estimation d), a plurality of compound velocities are estimated at different positions of the medium of interest, estimation d) further comprising: - generation, from the compound speeds, of cartographic data representative of the compound speeds, and / or of hardnesses estimated from said compound speeds, in respectively the different positions of the environment of interest.

[0022] According to one example, the process further comprises: - display of compound speeds, and / or hardnesses estimated from said compound speeds, in the form of at least one image or map.

[0023] According to one example, the method comprises, after a preliminary phase during which steps a) to d) are performed for each said distinct value of said at least one parameter, at least one periodic iteration of a cycle comprising: - estimation of at least one additional individual speed by iterating steps a) to c) for at least one of said values ​​of said at least one parameter; and - estimation of at least one compound shear wave velocity by repeating step d) using the additional individual velocity and at least one velocity individual estimated during a previous iteration of the cycle and / or during the preliminary phase.

[0024] According to a second aspect, the present disclosure may involve a computer program comprising instructions which, when the program is executed by a computer, cause the implementation of the process according to the first aspect. In particular, the various steps of the process according to the first aspect may be defined by instructions in computer programs.

[0025] Such a computer program may use any programming language or equivalent, and it may be in the form of source code, object code, or an intermediate form between source code and object code, such as in a partially compiled form, or in any other desirable form.

[0026] According to a third aspect, the present disclosure relates to a recording medium (or information medium), readable by a computer (or processor), on which a computer program is recorded according to this same aspect of the present disclosure.

[0027] On the one hand, the recording medium can be any entity or device capable of storing the program, such as at least one volatile and / or non-volatile memory. For example, the medium may include a storage means, such as rewritable non-volatile memory, ROM, CD-ROM, or microelectronic circuit-type ROM, or even a magnetic recording means or a hard drive. This memory may, for example, include graphics card (or video card) memory, this type of memory being particularly suited to processing image data (or video data).

[0028] On the other hand, this recording medium may also be a means based on transmissible signals such as an electrical or optical signal, such a signal being able to be transmitted via an electrical or optical cable, by conventional or radio frequency, by self-directing laser beam, or by other means. The computer program according to this disclosure may, in particular, be downloaded via a wired or wireless network, whether local or not (e.g., Bluetooth®, Wi-Fi, Ethernet, Internet, 4G, 5G, or others).

[0029] Alternatively, the recording medium may be an integrated circuit in which the computer program is incorporated, the integrated circuit being adapted to execute or to be used in the execution of the process in question.

[0030] According to a fourth aspect, the present disclosure relates to an ultrasonic elastography processing device, also called a processing device, configured to implement the method of the first aspect of the present disclosure.

[0031] According to one example, the processing device includes a memory associated with a processor, this memory including a computer program according to the present disclosure.

[0032] By way of example, the present disclosure relates to an ultrasound elastography processing device, said device comprising: - a data acquisition module configured to obtain initial representative data of an ultrasonic response, of a medium of interest, to ultrasonic pulses focused in said medium in combination with sounding waves emitted in said medium sequentially according to distinct values ​​of at least one parameter of said sounding waves; - a generation module configured to generate, from the first data respectively for each value of said at least one parameter, second data representative of a propagation of shear waves in the medium of interest under the effect of ultrasonic pulses; - a first estimation module configured to estimate, from the second set of data associated with each value of said at least one parameter, an individual velocity representative of the shear wave propagation velocity for said value respectively; and - a second estimation module configured to estimate at least one speed, called the compound speed, of the shear waves by a combination of the individual speeds.

[0033] It should be noted that the various embodiments mentioned above (as well as those described below) in relation to the treatment process of the invention and the associated advantages apply analogously to the treatment device of the invention. For each step of the treatment process, the treatment device of the invention may include a corresponding module configured to perform said step.

[0034] According to one embodiment, the invention is implemented by means of software and / or hardware components. In this context, the term "module" may refer in this document to a software component, a hardware component, or a set of hardware and / or software components.

[0035] According to a fifth aspect, the present disclosure relates to a processing system comprising: - the processing device according to the fourth aspect of disclosure; and - at least one ultrasonic probe configured to focus ultrasonic pulses into said medium and / or emit ultrasonic probing waves into said medium.

[0036] By implementing this disclosure, it becomes advantageously possible to efficiently process ultrasound elastography data to enable a Accurate and reliable estimation of the speed of shear waves propagating in a medium of interest. In particular, the disclosure provides for the processing of initial data representative of an ultrasonic response, of a medium of interest, to ultrasonic pulses focused in the medium in combination with sounding waves in which at least one parameter is varied over time.

[0037] By generating individual speeds associated respectively with different values ​​of a parameter of the sounding waves which are varied, one can advantageously obtain multiple estimates of the speeds of the shear waves for a given position of the medium 4. By combining these individual speeds obtained for each value of the parameter, for example by calculating an average or any other appropriate combination, one can thus obtain a quality estimate of the speed of the shear waves propagating in a medium.

[0038] The features and advantages of this disclosure will become clearer upon reading the following description, given solely by way of non-limiting examples, and with reference to the accompanying figures. In particular, the examples illustrated in the figures may be combined with each other, except in cases of obvious inconsistency. Brief description of the figures

[0039] Other features and advantages of this disclosure will become apparent from the description of the non-limiting examples of implementation of this disclosure set out below, with reference to the attached Figures 1 to 16, in which:

[0040] [Fig.1] schematically represents an ultrasonic system capable of performing an ultrasonic scan according to at least one embodiment of the present disclosure;

[0041] [Fig.2] schematically represents the emission of compression waves in a region of interest to cause shear waves, according to at least one embodiment of the present disclosure;

[0042] [Fig.3] schematically represents the emission of sounding waves in a region of interest to analyze the propagation of shear waves in said region, according to at least one embodiment of the present disclosure;

[0043] [Fig.4] schematically represents the variation of a parameter (emission angle) of the sounding waves emitted in a region of interest, according to at least one example of an embodiment of the present disclosure;

[0044] [Fig.5] schematically represents the variation of a parameter (frequency) of the sounding waves emitted in a region of interest, according to at least one example of an embodiment of the present disclosure;

[0045] [Fig.6] schematically represents a processing system, and a processing device, according to at least one embodiment of the present disclosure;

[0046] [Fig.7] schematically represents a processing system, and a processing device, according to at least one embodiment of the present disclosure;

[0047] [Fig.8] schematically represents a processing system, and a processing device, according to at least one embodiment of the present disclosure;

[0048] [Fig.9] schematically represents, in the form of a diagram, the steps of a processing procedure implemented by a processing device, according to at least one example of an embodiment of the present disclosure;

[0049] [Fig. 10] schematically represents the implementation of the processing method of [Fig.9], according to at least one example of embodiment of the present disclosure;

[0050] [Fig. 11] schematically represents the processing method of [Fig. 9] according to at least one example of the implementation of this disclosure; and

[0051] [Fig. 12] schematically represents data generated during the processing of the [Fig.9], according to at least one example of implementation of this disclosure;

[0052] [Fig. 13], [Fig. 14] and [Fig. 15] schematically represent the implementation of the processing method for [Fig. 9], according to at least one embodiment of this disclosure; and

[0053] [Fig. 16] schematically represents the processing method of [Fig.9] according to at least one embodiment of the present disclosure. Description of the implementation methods

[0054] This disclosure relates to the processing of ultrasonic elastography data, that is to say, data obtained by an ultrasonic study (a scan) of a region of interest in ultrasonic elastography mode, also called shear wave elastography mode or SWE for "ShearWave® Elastography".

[0055] A scan, as defined in this disclosure, corresponds to an ultrasound scan, an ultrasound observation, or an ultrasound observation phase; that is, a phase of emission and reception of ultrasound waves toward the observed medium, and respectively from said medium. Such a scan includes the propagation of ultrasound waves in a region of interest and the recovery of a return ultrasound response, that is, ultrasound echoes emitted by the region of interest. A scan makes it possible to obtain (or generate) ultrasound data representative of the region of interest. This data can then be used, for example, to characterize the medium, construct images, or establish representative maps of the studied medium, although other uses of ultrasound data are possible.

[0056] In shear wave elastography mode, an ultrasonic scan provides ultrasonic data which, once processed, provides information on the elasticity and stiffness of the observed region of interest. The principle of this ultrasonic mode is described below with reference to the figures.

[0057] As illustrated in [Fig. 1] by way of example, it is possible to use an ultrasound system SY1 comprising a transmitter device 2 and a control device 5 to perform an ultrasound scan of a region (or medium) of interest 4, for example in a part of a subject's body (a human or animal body, for example). To do this, the ultrasound probe 2 is driven by the device 5 to emit ultrasound waves W1 in the region of interest 4. In the particular example of ultrasound imaging, the ultrasound echoes W2 received back from the region of interest 4 are used in particular to characterize the region of interest 4. A representative ultrasound image of this region can in particular be generated from the received ultrasound echoes W2.

[0058] The ultrasonic emitting device 20 is, for example, an ultrasonic probe (or echographic probe) configured to emit ultrasonic waves W1 towards the region of interest 4 in response to one or more electrical signals SGI provided by the control device 5. To do this, the control device 5 may in particular include a control unit 6 comprising one or more electronic pulsers (more simply called "pulsers") or linear amplifiers, configured to generate the electrical signal(s) SGI intended to drive the ultrasonic probe 2.

[0059] The ultrasonic probe 2 may include one or more ultrasonic transducers 2a ([Fig.2]), each of which is driven by an electrical signal SGI delivered by the control device 5. In response to the received electrical signals SGI, the transducers 2a produce ultrasonic waves W1 towards the region of interest 4. The transmission of the electrical signals SGI can be ensured by a link from the pulsers to the transducers 2a of the probe 2.

[0060] The ultrasonic probe 2 can therefore be configured to emit, during a transmission operation, ultrasonic waves W1 towards the region of interest 4 and to receive back, during a reception operation, ultrasonic waves W2 from the region of interest 4, for example in the form of ultrasonic echoes caused by the W1 waves. Thus, each transducer 2a can be configured to convert an electrical signal SGI supplied by the control device 5 into ultrasonic waves W1 and vice versa. Note, however, that different probes 2 can be used for the transmission and reception operations, respectively.

[0061] The transducer elements 2a can be arranged in various configurations as appropriate, for example in a line of transducers, a matrix, or in a network of transducers or any other suitable configuration.

[0062] As illustrated in Figures 2 and 3 by way of example, the SY1 system comprising the probe 2 and the control device 5 can in particular be configured to operate according to a shear wave elastography mode, also called ShearWave® mode or “ShearWave® Elastography”.

[0063] Generally, the ultrasonic elastography method comprises an excitation phase of the region of interest by emission of ultrasonic waves and an acquisition and processing phase during which ultrasonic data emitted back from the region of interest are acquired and processed. More specifically, in pulsed elastography, the probe 2 is used to emit ultrasonic pulses 8 focused into the region of interest 4 ([Fig. 2]). These ultrasonic pulses 8, typically emitted as pulse bursts, form compression waves causing mechanical stresses in the region of interest. In the region of the focal point 10, a phenomenon known as "acoustic radiation pressure" occurs, whereby energy transfer caused by the pulses 8 generates material displacements in the medium under study, which in turn generates shear waves 12 propagating laterally around the focal point 10.Through an analysis of these shear waves 12, we can estimate the speed (or velocity) of these waves and deduce the rigidity and / or elasticity of the medium.

[0064] The detection and analysis of the displacement of the shear waves 12 are carried out by means of the emission of sounding waves 14 in the region of interest 4 ([Fig. 3]). To this end, the ultrasonic probe 2 can be configured to alternately emit ultrasonic pulses 8 and sounding waves 14 in the region of interest 4. The ultrasonic pulses 8 excite the region of interest 4 to form the shear waves 12, while the sounding waves 14 are emitted to obtain an ultrasonic response 16 (in the form of backscattered echoes) which makes it possible to characterize these shear waves 12.

[0065] It will be assumed hereafter that the sounding waves 14 used are plane waves, by way of example, which advantageously allows for various emission angles and thus for covering an appropriate area of ​​the medium. It should be noted, however, that the type and characteristics of the sounding waves 14 can be adapted according to the specific need and medium being studied. Examples of embodiments using diverging ultrasonic waves or focused ultrasonic waves as sounding waves 14 are possible.

[0066] The ultrasonic response signals 16 can be acquired by the probe 2 and transmitted as DTI data, referred to as first data, to a processing device 20, as shown in [Fig. 3] according to an exemplary embodiment. The greater the hardness of the examined medium, the higher the speed of the waves shear 12 is high. By analyzing the initial DTI data, we can thus evaluate the speed (or velocity) of propagation of the shear waves 12 and deduce an estimate of the hardness and / or elasticity of the region of interest 4.

[0067] In particular, the speed, denoted c, of the shear waves 12 is directly related to the shear magnitude p by the following relation: p = p • c2 where p is the density of the region of interest 4 examined. By way of example, the density p in the human body is approximately equal to 1000 kg / m3.

[0068] Furthermore, the shear modulus p is directly proportional to the Young's modulus E according to the following expression:

[0069] [Math 1] E = 3 • (equation 1)

[0070] From the speed c of the shear waves 12, we can therefore deduce the Young's modulus E, and thus the hardness c, where:

[0071] [Math 2] E = 3 • p ■ c2 (equation 2)

[0072] As described below, the speeds of the shear waves, as well as the levels of stiffness or elasticity obtained, can be exploited in various ways, for example for the generation and display of parametric maps allowing visualization of hardness levels in the medium of interest 4, these maps can where appropriate be superimposed or associated with one or more ultrasonic images relating to the B mode (presented in shades of grey).

[0073] As illustrated in [Fig. 4], it is possible to vary over time the emission angle θ at which the sounding waves 14 are emitted, namely plane waves in the examples considered. By varying this angle θ, the accuracy of the estimation of the speed c of the shear waves 14 in the medium under consideration can be advantageously improved.

[0074] By way of example, the ultrasonic probe 2 can be configured to sequentially emit sounding waves 14 at distinct values ​​VL of the emission angle 0, for example, at three distinct values ​​denoted VL1, VL2, and VL3. By averaging the ultrasonic response 16 (Figures 3-4) collected by the probe 2 at the different VL1-VL3 values ​​of angle 0, a usable quality estimate of the speed of the shear waves 14 can advantageously be obtained, with a reduced noise level and better resolution, compared to a solution based on the analysis of the ultrasonic response 16 at a single emission angle 0 (a single angle value). This technique, known as ultrasonic data averaging, makes it possible to determine a statistically significant confidence estimate at different positions in the region of interest 4.

[0075] It should be noted, however, that the technique described above for averaging ultrasonic data only allows for the determination of a single estimate of the speed c of the shear waves 14 at each point studied, for a given ultrasonic scan. It has It has been observed that the results are not always satisfactory, particularly in terms of precision and reliability, which can hinder the characterization of the observed environment. When averaged ultrasonic data do not provide a sufficiently high-quality velocity estimate, a relevant result cannot be obtained, thus limiting the performance of this technique. For example, in medical imaging applications, it has been observed that ultrasonic data averaged across different VL angle values ​​do not always provide a sufficiently high-quality velocity estimate, sometimes leading to ignoring the result for certain points within the region of interest. This can result, for instance, in an area within the studied region where the information is unusable or where no useful information can be obtained in the resulting map image(s).

[0076] The present disclosure aims to address in particular the problems and constraints previously described, notably through an ultrasonic elastography processing method and a corresponding processing device, aimed at characterizing a region of interest from ultrasonic data obtained according to a shear wave elastography mode.

[0077] According to particular embodiments, the processing method thus comprises: a) obtaining first data representative of an ultrasonic response, of a medium of interest, to ultrasonic pulses focused in said medium in combination with sounding waves emitted in said medium sequentially according to distinct values ​​of at least one parameter of said sounding waves; b) generation, from the first data respectively for each value of said at least one parameter, of second data representative of a propagation of shear waves in the medium of interest under the effect of ultrasonic pulses; (c) estimation, from the second set of data associated with each value of said at least one parameter, of an individual speed representative of the speed of shear wave propagation for said value respectively; and d) estimation of at least one speed, called compound speed, of the shear waves by a combination of the individual speeds.

[0078] Other aspects and advantages of this disclosure will become apparent from the implementation examples described below with reference to the figures mentioned above.

[0079] Examples of embodiment of the present disclosure are described below in conjunction with Figures 1 to 16, in which the ultrasonic elastography processing device (also referred to as the processing device) 20 represented in particular in [Fig.3] is used to implement the ultrasonic elastography processing method (also referred to as the processing method) of the present disclosure.

[0080] Unless otherwise indicated or in the event of a notable inconsistency, common or similar elements in several figures bear the same reference signs and have identical or similar characteristics, so that these common elements are generally not described again, for the sake of brevity.

[0081] The terms "first(s)" (or first(s)), "second(s)", etc.) are used in this document by arbitrary convention to allow identification and distinction of different elements (such as modules, data, etc.) implemented in the embodiments described below.

[0082] As illustrated in Figures 2 and 3, the processing device 20 is configured to obtain first data denoted DTI, this data being representative of an ultrasonic response 16 of a region of interest 4 to ultrasonic pulses 8 focused in the region of interest 4 in combination with sounding waves 14. To do this, the ultrasonic pulses 8 and the sounding waves 14 can be emitted alternately over time in the region of interest 4. The ultrasonic pulses 8 generate the shear waves 12 in the region of interest 4 while the emission of sounding waves 14 makes it possible, from the response of the medium, to analyze the propagation of these shear waves 14 in said region.

[0083] It is assumed hereafter, by way of example, that the ultrasonic probe 2 (figures 1 to 4) is used to emit the ultrasonic pulses 8 in combination with the sounding waves 14. It should be noted, however, that the aforementioned waves 8 and 14 can be emitted by any suitable means, common or separate, whether by a single device or devices respectively responsible for the emission of the pulses 8 and the sounding waves 14.

[0084] It is subsequently assumed that the probe 2 forms with the processing device 20 a system, also called a processing system, denoted SY2 (figures 3 and 6).

[0085] The processing device 20 can obtain the first DTI data in various ways. According to one example, the processing device 20 can thus extract the first DTI data from an internal or external memory, or receive this DTI data from outside, for example from the ultrasonic system SY1 including the probe 2 or from any other suitable entity, such as a server for example.

[0086] The processing device 20 can be configured to process the first STI ultrasound data in real time or near real time, as the data are received from the probe 2 (or more generally from the ultrasound system SY1). According to another example, the first DTI data are generated during an ultrasound acquisition or scan phase, and then this DTI data are received and processed by the processing device 20 during a processing phase subsequent to the acquisition phase (for example, after an ultrasound scan phase).

[0087] The sounding waves 14 emitted by the ultrasonic probe 2 are configured to detect and follow the propagation of the shear waves 12 caused by the ultrasonic pulses 8 within the region of interest 4. It is assumed hereafter, by way of example, that plane ultrasonic waves are used as sounding waves 14 ([Fig.3]), which advantageously allows various emission angles to be obtained and thus a suitable area of ​​the medium to be covered quickly, although other types of sounding waves are possible.

[0088] The sounding waves 14 emitted by the probe 2 are characterized by at least one parameter, denoted PR, the number and nature of which can be adapted as needed. The sounding waves 14 are emitted sequentially in the region of interest 4 according to distinct values ​​VL, also called parameter values, of said at least one parameter PR. In other words, the value of the parameter(s) PR of the sounding waves 14 are modified (or adapted) over time so as to successively take on at least two distinct VL values.

[0089] For the sake of simplicity in the presentation of this disclosure, it is hereafter considered, for purely illustrative purposes, that the VL value of a single PR parameter is modified to generate the first DTI data, although other examples in which the VL values ​​of at least two PR parameters of the sounding waves 14 are modified are also possible.

[0090] For the sake of simplicity in the presentation of this disclosure, it is hereafter considered, purely for illustrative purposes, that the value of a PR parameter is modified during an ultrasonic scan so that this PR parameter sequentially takes on three distinct values ​​denoted VL1, VL2 and VL3. These values ​​VL1, VL2 and VL3 can be applied according to a repetitive pattern, for example by applying them successively in a cyclical manner (according for example to a sequence "VL1 - VL2 - VL3 - VL1 - VL2 -etc.").

[0091] According to an example illustrated in [Fig. 4], the emission angle 0 at which the sounding waves 14 are emitted into (or towards) the medium of interest 4 is used as a time-varying parameter PR. In other words, the probe 2 can be configured to vary the emission angle 0, as a parameter PR, so that the latter sequentially takes the values ​​VL1, VL2, and VL3, thus leading to the generation of shear waves 12 for these distinct values ​​VL1, VL2, and VL3, respectively.

[0092] In the example shown in [Fig. 4], the value VL2 is fixed at zero ([Fig. 4](B)) while the values ​​VL1 and VL3 are fixed at non-zero values ​​(Figures 4(A) and 4(C)). The values ​​VL1 and VL3 are, for example, distinct from each other. The emission angle 0 can, for example, vary so as to take either a negative value (VL1) or a positive value (VL3), which amounts to alternately orienting the waves of sounding 14 on either side of an axis normal to a surface of the region of interest 4. Other emission angle configurations are however possible.

[0093] It should be noted that other types of PR parameters for the sounding waves 14 are possible. Thus, according to an example illustrated in [Fig. 5], the emission frequency f at which the sounding waves 14 are emitted in the medium of interest 4 is used as a time-varying PR parameter. In other words, the probe 2 can be configured to vary the frequency f of the sounding waves 14 so that this frequency sequentially takes on distinct VL values, denoted respectively VF1, VF2, and VF3 in this example, thereby allowing the shear waves 12 to be observed at different frequencies of the sounding waves 14.

[0094] In the example shown in [Fig.5], parts (A), (B) and (C), the VL value gradually decreases from VL1 to VL3, although other examples are possible, such as in particular the reverse configuration where the VL values ​​gradually increase from VL1 to VL3.

[0095] According to one example, said at least one PR parameter which varies sequentially during the ultrasonic scan phase, comprises at least one of, or both of: - the emission angle 0 at which the sounding waves 14 are emitted in the direction of the medium of interest 4; and - the frequency f at which the sounding waves 14 are emitted towards the medium of interest 4.

[0096] Figure 6 represents the processing device 20 cooperating with the probe 2 according to an exemplary embodiment. As illustrated, the device 20 is configured to receive the first DTI data produced by the probe 2 (or more generally by the ultrasonic system SY1 of Figure 1), for example via a communication link 9 which can be a wired or wireless link as appropriate.

[0097] In the example considered, the processing device 20 and the ultrasonic probe 2 together form (or are part of) a processing system denoted SY2 (Figures 3 and 6). For the sake of example, the ultrasonic system SY1 ([Fig. 1]) and the processing system SY2 (Figures 3 and 6) are considered to form a single system. The processing device 20 and the control device 5 ([Fig. 1]) can, for example, form a single device. In this case, the processing device 20 is configured, on the one hand, to control the ultrasonic probe 2 by sending electrical signals SGI so as to emit waves 8 and 14, and on the other hand, to process the first DTI data, representative of the ultrasonic response 16 of the medium 4, received back by the ultrasonic probe 2.

[0098] Other examples in which the processing device 20 and the control device 5 are separate are also possible. The processing device 20 may for example, being a server, or any other computer means, capable of obtaining and processing the first DTI data.

[0099] As illustrated in [Fig. 6] by way of example, the processing device 20 comprises a processor 22 and a memory 24. The memory 24 is capable of storing, in the form of a computer program PG1, instructions defining the steps of the processes described in this disclosure. As such, the memory 24 constitutes a storage medium (or information carrier) conforming to particular embodiments, readable by the processing device 20, and on which a computer program PG1 conforming to particular embodiments is stored. This computer program PG1 contains instructions for executing the steps of a processing method (also called an ultrasonic elastography processing method), particular embodiments of which are described in this disclosure.Processor 22 is thus configured to execute the instructions of the computer program PG1 in order to carry out steps in the disclosure processing procedure.

[0100] Depending on the configurations and types of computer device considered, the memory 24 may include volatile memory (such as RAM) and / or non-volatile memory (such as ROM, flash, EEPROM, etc., or any other computer-readable storage device and / or medium as described below, or a combination of these examples of memory categories.

[0101] The memory 24 can, for example, be managed in DMA (Direct Memory Access) mode. This memory 24 used by the processing device 20 can, for example, include all or part of a graphics card (or video card) memory, this type of memory being particularly capable of processing and / or sending image data that can be used to display one or more images on a display screen (or unit).

[0102] The memory 24 is capable of storing various data that can be used from the processing device 20 during the disclosure processing method, such as in particular the aforementioned first DTI data, second ultrasonic data DT2 generated from the first DTI data, and velocity estimates, namely at least one individual speed VI (for example V11, VI2 and VI3) representative of the speed of movement of the shear waves 12 in the region of interest 4 and at least one compound speed VC of the shear waves 12. The nature and function of this data will become more precisely apparent below, in examples of embodiments of the processing device 20 and the disclosure method.

[0103] The processing device 20 may take the form of various suitable computing means (such as, for example, a workstation, computer, server, etc.) comprising all or part of the elements described above as well as possibly other elements not mentioned. In general, the processing device 20 includes appropriate means to implement the steps of the processing procedure as described below in examples of implementation of this disclosure.

[0104] The SY2 ultrasonic system (Figures 3 and 6) can be an ultrasonic imaging system, for example used in the medical or veterinary field. The ultrasonic images generated by the SY2 system can be analyzed either in real time, for example by a user or an algorithm, and / or an artificial intelligence module, or analyzed later and / or in a location other than that in which the SY2 system is located.

[0105] The SY1 ultrasonic system can be a medical ultrasound system. Similarly, the probe 20 can be a medical ultrasound probe. Also, the SY2 treatment system can be a system applied in the medical field, although other applications are possible.

[0106] By way of example, the SY2 system can be associated with the ultrasonic probe 2 to study a medium 4 ([Fig. 2]), in particular to collect and process initial DTI data characterizing such a medium 4 using shear wave elastography. The medium 4 thus observed can be of various types, depending on the case. It can be, for example, metals, tissues of living organisms, in particular human or animal tissues. Observation of a medium 4 comprising one or more mineral structures, for example, is also possible (gravel, volcano, mapping of a soil, for example, of the seabed, etc.).

[0107] The SY2 processing system can therefore be configured for various applications, particularly in the fields of acoustics, materials science, medical and veterinary imaging, and / or biomedicine. The SY2 system can be implemented in applications other than ultrasound imaging, for example, to characterize a region of interest from initial DTI data without generating an ultrasound image.

[0108] Figure 7 schematically represents a non-limiting example of an embodiment of the processing device 20, and more generally of the processing system SY2, as previously described in conjunction with Figures 1-6, namely in this case an ultrasound imaging device. In this example, the processing device 20 is contained within the body of a control station, the latter also being equipped with a control interface and one or more display devices. The control station may also include the control device 5 ([Fig. 1]) described previously. The probe 2 is, for example, connected in a communicating manner to the processing device 20 (and the control device 5) via a link 9 which takes here the form of a connection cable, although variants are possible in which, for example, the connection is made via a wireless link.

[0109] The SY2 processing system can be configured to produce an ultrasonic image of various types, for example a so-called B-mode image of the medium M (B-mode image, presented in greyscale), a so-called Doppler image illustrating fluid movements in the observed medium, and / or an image showing a mechanical characteristic of the medium (for example, elastography image data obtained using shear waves (“ShearWave®Elastography”)). According to one example, the electrical signal SGI transmitted by the control device 5 thus causes the ultrasonic probe 2 to emit W waves, namely ultrasonic pulses 8 ([Fig.3]) in combination with sounding waves 14 ([Fig.4]).

[0110] As shown in [Fig.8] according to one embodiment, the processor 22 of the processing device 20, controlled by the computer program PG1 ([Fig.6]), can implement a number of modules, namely: an acquisition module MD2, a generation module MD4, a first estimation module MD6 and a second estimation module MD8, and possibly also a third estimation module MD10.

[0111] More specifically, the MD2 acquisition module is configured to obtain first DTI data representative of an ultrasonic response 16, of a medium of interest 4, to ultrasonic pulses 8 focused in said medium in combination with sounding waves 14 emitted in said medium sequentially according to distinct values ​​VL (for example VL1 to VL3) of at least one parameter PR (for example the emission angle 0) of said sounding waves (Figures 1-6).

[0112] The MD4 generation module is configured to generate, from the first DTI data respectively for each VL value of said at least one PR parameter, second DT2 data representative of a propagation of shear waves 12 in the medium of interest 4 under the effect of ultrasonic pulses 8.

[0113] The first estimation module MD6 is configured to estimate, from the second data DT2 associated with each value VL of said at least one parameter PR, an individual speed VI (for example Vl to VI3, respectively) representative of the speed of movement of the shear waves 12 for respectively said value (for example VL1 to VL3, respectively).

[0114] The second estimation module MD8 is configured to estimate at least one velocity VC (for example VC1 to VC3, respectively), called compound velocity, of the shear waves 12 by a combination of the individual velocities VI.

[0115] The third estimation module MD10 is, where appropriate, configured to estimate, from said at least one compound velocity VC, a hardness (or elasticity) of the medium of interest 4.

[0116] The configuration and operation of the MD2, MD3, and MD4 modules of the control device 10 will be shown more precisely in the embodiment examples described below with reference to the figures. The MD2, MD3, and MD4 modules as shown in [Fig. 4] represent only one non-limiting implementation example of the disclosure.

[0117] Generally, for each step in the process of processing this disclosure, the disclosure processing device 20 may include a corresponding module configured to carry out said step (and vice versa).

[0118] Embodiments of the disclosure processing method are now described with reference to Figures 9 to 16. In these examples, the processing method is implemented by the processing device 20, and more generally by the processing system SY2, as previously described jointly in Figures 1 to 8. To do this, the processing device 20, cooperating with the ultrasonic probe 2, can execute the computer program PG1.

[0119] During a step S2 of acquisition ([Fig.9]), the processing device 20 obtains first DTI data representative of an ultrasonic response 16, of a medium (or region) of interest 4, following emission of ultrasonic pulses 8 focused in said medium 4 in combination with sounding waves 14 emitted in said medium 4 sequentially according to distinct values ​​VL of at least one parameter PR of the sounding waves 14.

[0120] In other words, the first DTI data represent ultrasonic echoes 16 emitted by the medium 4 in response to the ultrasonic pulses 8 combined with the sounding waves 14 (Figures 2 and 3). These sounding waves 14 are characterized by at least one PR parameter that varies over time. Thus, the VL value of said at least one PR parameter varies sequentially during the ultrasonic scan phase so as to successively take on different values. The VL value of the PR parameter(s) can be modified under the control, for example, of the control device 5 ([Fig. 1]).

[0121] More particularly, the ultrasonic response 16 defined by the first DTI data characterizes shear waves 12 caused by ultrasonic pulses 8 focused in the region of interest 4. These ultrasonic pulses 8, emitted for example in the form of pulse shots, form compression waves causing mechanical stresses in the region of interest 4. In the region of the focal point 10 ([Fig.3]), an acoustic radiation pressure phenomenon occurs whereby an energy transfer generates displacements of matter in the medium examined, which generates shear waves 12 propagating in particular laterally around the focal point 10.

[0122] The first DTI data are acquired by the ultrasonic probe 20 during an acquisition phase, corresponding to one or more ultrasonic scans in Shear wave elastography is performed according to the principle described above with reference to Figures 2 and 3. This initial DTI data is then transmitted from the probe 20 to the processing device 20, for example, via the communication link 9. However, this initial DTI data can be obtained by the processing device 20 in other ways, depending on the circumstances. In particular, the ultrasonic scan can, for example, be performed first, and then the processing device 20 can obtain this initial DTI data later, in any suitable manner. For example, the processing device 20 can retrieve the initial DTI data from internal or external memory, or receive this DTI data from an external source, for example, from the ultrasonic system SY1 comprising the probe 2, or from any other suitable entity, such as a server.

[0123] It is hereafter assumed, by way of example, that the sounding waves 14 are ultrasonic plane waves, although other examples are possible. According to another example, the sounding waves 14 are diverging or focused ultrasonic waves. According to one example, the sounding waves 14 comprise at least one of the aforementioned wave types.

[0124] It is assumed hereafter, for purely illustrative purposes, that the emission angle θ at which the sounding waves 14 are emitted is used as the PR parameter of the sounding waves 14. It should be noted, however, that the disclosure processing method can be carried out analogously, according to one embodiment, by varying the value of the frequency f of the sounding waves 14 as the PR parameter. However, in the remainder of this description, for the sake of simplification, only the example based on the emission angle θ as the PR parameter will be illustrated.

[0125] Thus, during the acquisition phase, the ultrasonic probe 2 emits the sounding waves 14, varying the value VL of the emission angle 0 over time (Figures 4 and 6). In the example considered, the probe 20 sequentially emits the sounding waves 14 according to N distinct values ​​VL of the emission angle 0 (where N is an integer at least equal to 2), which results in a variation in the orientation of the sounding waves 14 over time. As an example, we subsequently assume that N=3 and that the emission angle 0 successively takes the distinct values ​​VL1, VL2, and VL3. These VL1, VL2 and VL3 values ​​can for example be applied repeatedly (according to a repetitive pattern), for example by successively assigning them cyclically to the emission angle 0 (according for example to a sequence "VL1 - VL2 -VL3 - VL1 - VL2 - etc.").

[0126] According to an example, prior to step S2 of obtaining the first DTI data by the processing device 20, the probe 20 (or more generally the SY2 processing system) performs the following steps: - formation of shear waves 12 in the medium of interest 4 by focusing ultrasonic pulses 16; and - emission, in the medium of interest 4, of sounding waves 14 configured sequentially according to the distinct values ​​VL1-VL3 of the PR parameter (namely the emission angle 0 for example) to detect the ultrasonic response 16 of the medium of interest 4 for each value VL of the PR parameter.

[0127] During a generation step S4 ([Fig.9]), the device 20 generates, from The first DTI data, for each VL value of the PR parameter (i.e., the emission angle 0 in this example), generates second DT2 data representing the propagation of shear waves 12 in the medium of interest 4 under the influence of ultrasonic pulses 8 (Figures 2-3). In other words, the device 20 processes the first DTI data and, from this processing, generates second DT2 data for the VL1, VL2, and VL3 values ​​of the emission angle 0 of the sounding waves 14. These second DT2 data represent the displacement of the shear waves 12 in the medium 4.

[0128] The configuration of these second data can vary depending on the case. According to an example illustrated in [Fig. 10], these second data DT2 define, for each value VL1, VL2 and VL3 of the emission angle 0, a sequence of images IM1 representative of the propagation of the shear waves 12 caused by the ultrasonic pulses 8 in the medium of interest 4. The device 20 thus generates a plurality of image sequences IM1 in association respectively with the different values ​​VL of the emission angle 0.

[0129] Each IM1 image (or frame) can represent a shear wave position at a given instant. Two consecutive IM1 images then represent an estimate of the displacement between two corresponding acquisitions for a given VL value of the PR parameter under consideration. Thus, a series of IM1 images for a given VL value can represent a displacement of the medium (and of the shear waves 12) over time. From a phase shift (or changes) between two successive IM1 images for a given VL value, the device can deduce a displacement of the shear waves 12. It should be noted, however, that the IM1 images thus produced are not necessarily generated, stored, and / or displayed or returned to a user, although this is possible.

[0130] During an estimation step S6 ([Fig. 9]), the device 20 estimates, from the second data DT2 associated with each value VL of the parameter PR (i.e., the emission angle 0 in this example), an individual speed VI representative of the speed of propagation of the shear waves 12 for said value VL respectively. Thus, the device 20 determines, on the basis of the second data DT2, the individual speeds V1, VI2 and VI3 representative of the speeds of the waves shear 12 for respectively the values ​​VL1, VL2 and VL3 of the emission angle 0 ([Fig. 10]).

[0131] The individual speeds VI are determined for example (S6, [Fig.9]) by analysis of the IM1 images defined by the second data DT2. By comparing a series of IM1 images obtained for a given value VL, for example by estimating a phase shift (or changes) between two successive IM1 images for the given value VL, the device 20 can calculate a corresponding speed VI at each point of the region of interest 4.

[0132] During an estimation step S8 ([Fig. 9]), the device 20 estimates at least one speed VC, called the compound speed, of the shear waves 12 by combining the individual speeds VI previously obtained (in S6). At least two individual speeds VI estimated in S6 are combined to determine the compound speed VC. Thus, in this example, the device 20 combines the individual velocities V1, VI2, and VI3, associated respectively with the values ​​VL1, VL2, and VL3, to deduce the compound speed VC.

[0133] Figure 11 illustrates an example of implementing steps S6 and S8 of the processing method. In step S6, the device 20 determines, by processing the first received data DTI, second data DT2 defining a sequence of images IM1 corresponding successively to the values ​​VL1, VL2, and VL3, cyclically, over time. The device 20 requires at least two images (or frames) IM1 for a given value VL in order to compare them and deduce a corresponding individual velocity VI for said value V. To do this, the device 20 can therefore store in memory the IM1 images it determines over time and compare a plurality of IM1 images obtained for the same given value VL to deduce a corresponding individual velocity VL. This process can be carried out analogously for each value VL1, VL2, and VL3 in order to deduce individual velocities V1, V12, and VL3, respectively.These individual velocities Vil, V12 and -VI3 are then combined to deduce a compound velocity VC during the estimation step S8.

[0134] The way in which the individual speeds VI obtained in S6 are combined (S8) to determine the compound speed VC may vary depending on the case. In one example, the combination of the individual speeds V11, V12, and -VI3 is determined by calculating an average of the individual speeds VI to estimate the compound speed VC. It is subsequently assumed that the device 20 calculates a compound speed VC from an average of the individual speeds V11, V12, and VI3. A similar process can be performed by the device 20 to estimate a plurality of compound speeds VC. In particular, compound speeds VC can be determined (S8) in association with respective positions of the medium of interest 4. Note that calculations other than averages, also combining individual speeds VI to determine the compound speed VC, are possible.

[0135] The average calculated in S8 can be a weighted average according to weights K assigned respectively to each individual speed VI, which advantageously allows for an intelligent combination of speed estimates according to different values ​​VL of the parameter PR considered.

[0136] According to one example, the device 20 assigns (S8a, [Fig. 9]) weights (or coefficients) K1, K2, and K3 respectively to the individual speeds V1, V12, and V13. These weights K1-K3 are determined based on at least one characteristic of the second set of data DT2 generated respectively for each value VL1, VL2, and VL3 of the parameter PR under consideration. The device 20 estimates the compound speed VC by calculating the average, weighting the individual speeds V1, V12, and V13 according to the associated weights K1, K2, and K3. In other words, the compound speed VC can then be defined according to the following expression:

[0137] [Math 3] VC = Kl • VH + K2- Vn+Ki- VI3 (equation 3)

[0138] The characteristic(s) of the second DT2 data, which are used to determine the K1-K3 weightings, can be adapted as appropriate. These characteristics may, for example, be representative of a quality level of the second DT2 data, or of the IM1 images defined on the basis of this second DT2 data (Figures 9-10).

[0139] It is thus advantageously possible to adapt the preponderance or weight, in the compound mean VC, of ​​the individual speeds VI according to the relevance or quality of the corresponding ultrasonic responses 16 obtained according to the various values ​​VL of the parameter PR considered (namely the emission angle 0 in this example). For example, only the relevant individual speeds VI for each pixel of the IML images can be taken into account. This weighting is made possible by the fact that a plurality of individual speeds V1, V12 and VI3 are obtained, associated with respective values ​​VL1, VL2 and VL3 of the parameter PR, which offers a substantial volume of usable data from which the most relevant individual speeds VI can be advantageously selected and, where appropriate, the importance of each individual speed VI in the calculation of the compound speed VC can be adjusted.

[0140] According to one example, at least two individual speeds among V11, V12, and VI3 are selected in S8 ([Fig. 9]) to be taken into account in the calculation of the composite value VC. At least one individual speed VL, for example VL1, may be excluded from the combination of individual speeds VI performed in S8, for example, if it is detected that this individual speed VL is associated with second data points DT2 that do not meet at least one predetermined quality criterion. At least one weight K can thus be set to zero (K = 0) to exclude a corresponding individual speed VI from the calculation of the compound speed VC, which advantageously allows us to retain only the most relevant individual speeds VI in the calculation of the average in S8b ([Fig.9]).

[0141] According to one example, during the estimation step S8, the device 20 determines spatial variances characterizing the second data points DT2 associated with each value VL of the parameter PR under consideration. The device 20 then determines, from the spatial variances thus obtained, confidence scores associated with the individual speeds VI. Such a confidence score, associated with an individual speed VI, represents a probability that the individual speed VI is reliable (or acceptable). The respective weight K assigned to each individual speed VI can then be a function of the associated confidence score. It is thus advantageously possible to weight the importance given to each individual speed VI in determining the combined speed VC, so as to obtain an accurate and reliable estimate of the combined speed of the shear waves 12.

[0142] According to one example, during the estimation step S8, the device 20 compares each confidence score thus obtained with a reference value (for example, a threshold value). If a confidence score associated with second data points DT2 corresponding to a value VL does not satisfy at least one quality criterion (a function of the result of this comparison), the weight K assigned to the individual velocity VI associated with this value VL is zero (K is set to 0) so as to exclude said individual velocity VI from the estimation (S8) of the compound velocity VC. Thus, if a confidence score ([Fig. 10]) corresponding to a given value VL of the emission angle 0 is, for example, less than a threshold value, the associated individual velocity VI is not taken into account in the calculation (S8) of the compound velocity VC, which advantageously maximizes the reliability and precision of the result thus obtained.By taking into account the confidence scores in the estimation of the compound velocity VI, it is thus possible to select the most relevant individual velocities VI and thus advantageously minimize the probability of obtaining "dead pixels" in the IM2 images, i.e. pixels for which the image data are considered unusable for estimating the compound velocity VC of the shear waves 12. .

[0143] The combined speed(s) VC determined in S8 ([Fig.9]) can then be used in various ways depending on the case. According to one example, during an estimation step S10 ([Fig.9]), the device 20 performs an estimation, from the combined speed(s) VC, of ​​a hardness (or stiffness, or elasticity) of the medium of interest 4.

[0144] According to one example, device 20 triggers a rendering (visual, vocal, etc.), for example by display, of the compound velocity estimate(s) VC. Compound speeds VC are, for example, displayed on a screen as at least one IM2 image. This screen can be included in the SY2 processing system, as illustrated as an example in [Fig.7]; it can be located remotely in the same environment or separated and / or away from the processing system.

[0145] According to one example, the device 20 causes the display of the compound speed(s), and / or the hardness(es) estimated from the compound speed(s), in the form of at least one IM2 image (for example in the form of an elastogram), for example in the form of a sequence of IM2 images which may optionally form a video which a user can view, either immediately after obtaining the image sequence, in quasi-simultaneous or dissociated manner.

[0146] It is subsequently assumed that the device 20 also generates, at S10, third DT3 data points representing compound velocities VC determined at S8 ([Fig. 9]). The nature of these third DT3 data points may vary depending on the case. These DT3 data points may, in particular, take the form of image data defining IM2 images representing the compound velocities VC determined at S8 at different positions in the region of interest 4.

[0147] As illustrated in [Fig. 12] by way of example, the third data DT3 generated in S10 ([Fig.9]) can define a parametric map (or map image) IM2 representing, in different pixels of said map, the compound speed VC of the shear waves 12 and / or the corresponding hardness of the medium 4. Each pixel of this map image IM2 corresponds to a respective position of the region of interest 4.

[0148] According to an example, during the estimation S8 ([Fig.9]), a plurality of compound velocities VC is estimated in different positions of the medium of interest 4. The device 20 then generates (S 10) from the compound velocities VC, cartographic data DT3 representative of the compound velocities VC, and / or of hardnesses estimated from the compound velocities VC, in respectively the different positions of the medium of interest 4. These IM2 images can then be displayed or rendered according to one of the modes for example indicated above.

[0149] As already described with reference to [Fig. 11], the second DT2 data determined at S6 ([Fig. 9]) can define a sequence of IM1 images corresponding successively to the values ​​VL1, VL2, and VL3, these VL values ​​repeating cyclically over time. Steps S2 to S10 ([Fig. 9]) can thus be repeated over time to determine, from each new ultrasound acquisition, at least one compound velocity VC.

[0150] Figures 13, 14 and 15 schematically represent the sequence of the treatment process of [Fig. 9] according to an example embodiment. During a preliminary phase PHI ([Fig. 13]), steps S2 to S8 are carried out for three values The device 20 uses distinct VL1, VL2, and VL3 values ​​from the emission angle 0, which is used as the variable parameter PR of the sounding waves 14. During this preliminary phase PH1, the device 20 determines (S4) from the second data DT2, defining at least two IM1 images for each VL1-VL3 value of the PR parameter, in order to deduce (S6) by comparing the individual velocities VI1-VI3, respectively. For the sake of simplifying the disclosure statement, it is hereafter assumed that the device 20 estimates each individual velocity VI by comparing only two IM1 images for a given VL value, although a larger number of IM1 images could be processed for the same VL value to deduce a corresponding individual velocity VI. The device 20 can thus estimate a composite velocity VC, denoted VCO, from the individual velocities VI1-VI3 according to step S8 ([Fig. 9]) described previously.

[0151] After this preliminary phase PHI, at least one periodic iteration of a cycle S15 ([Fig. 14]) is performed by the device 20. During this cycle S15, the device 20 determines new IM1 images for the values ​​VL1-VL3 respectively and estimates new individual speeds VI1-V3 by repeating steps S2 to S6 ([Fig. 9]) using the new IM1 images as well as IM1 images obtained previously during the preliminary phase PHI. From the new individual speeds VI1-VI3 thus obtained, the device 20 can then deduce a new combined velocity VC, named VC1, by repeating the estimation step S8 ([Fig. 9]) as already described.

[0152] As illustrated in [Fig. 15], the S15 cycle can thus be repeated as many times as necessary to update the compound velocity VC over time, at each target position in the region of interest 4. For example, during a second iteration of the S15 cycle, the device 20 determines new IM1 images for the values ​​VL1, VL2, and VL3 respectively and estimates new individual speeds V11, V12, and V3 by repeating steps S2 to S6 ([Fig. 9]) using the new IM1 images as well as old IM1 images obtained during the previous iteration of the S15 cycle. From the new individual speeds V11, V12, and V3 thus obtained, the device 20 can then deduce a new compound velocity VC, named VC2, by repeating the estimation step S8 ([Fig. 9]) as already described.

[0153] This iterative process can be carried out to estimate compound speeds VC in multiple points (or positions) in the region of interest 4. In this way, new estimates of compound velocities VC can be generated quickly and advantageously with minimal latency while maintaining good estimation quality. This technique can be used to generate real-time velocity estimates. For each new ultrasonic response 16 ([Fig. 3]) obtained for different values ​​VL1, VL2, and VL3, second data DT2 can be deduced and used these in combination with second DT2 data from at least one previous iteration of the cycle, so as to guarantee the robustness of the result while minimizing latency times.

[0154] According to an example illustrated in Figures 13 and 16, it is assumed that the device 20 performs the preliminary phase PHI as previously described with reference to [Fig. 13]. Once this preliminary phase PHI has been completed, at least one periodic iteration of a cycle S20 is performed by the device 20 ([Fig. 6]). During this cycle S20, the device 20 determines a new image IM1 for a given value VL, for example VL1 as illustrated in [Fig. 16], by repeating steps S2 and S4 ([Fig. 9]) as previously described. The device 20 then estimates a new individual velocity VH by repeating the estimation step S6 ([Fig. 9]) using the new image IM1 as well as the previous IM1 images obtained for the value VL1 during the preliminary phase PHI.Device 20 can then estimate a new compound velocity VC, named VC1, by combining the new individual velocity VH with the old individual velocity values ​​VI2 and VI3 previously obtained during the preliminary phase PHI for the values ​​VL2 and VL3 respectively.

[0155] As illustrated in [Fig. 16], the S20 cycle can thus be repeated as many times as necessary to successively update at least one individual velocity VI, and thus update the combined velocity VC over time, at each target position of the region of interest 4. For example, during a second iteration of the S20 cycle, the device 20 determines a new image IM1 for the value VL2 and estimates a new individual velocity VI2 by iterating steps S2 to S6 ([Fig. 9]) using the new image IM1 obtained during this second iteration and the old images IM2 obtained, for the value VL2, during the previous iteration of the S20 cycle and the preliminary phase PHI, respectively. This new individual velocity VI2 can then be combined again with the old individual velocities VH and VI3 used during the previous iteration of the S20 cycle.

[0156] This iterative process can be used to estimate compound velocities VC at multiple points in the region of interest 4. In this way, new estimates of compound velocities VC can be generated rapidly with minimal latency while maintaining good estimation quality. This technique can be used to generate velocity estimates in real time. For each new ultrasonic response 16 (see [Fig. 3]) obtained for a given VL value, at least one additional individual velocity VI can be combined with at least one individual velocity estimated during a previous iteration of the cycle, so as to guarantee the robustness of the result while minimizing latency times.

[0157] The above examples of implementation of the method of this disclosure are described in the case where the emission angle 0 varies as the PR parameter. Note, however, that the disclosure can be applied analogously by varying, as the PR parameter, another PR parameter of the sounding waves 14, for example by varying the frequency f ([Fig.3]) of the sounding waves 14 emitted in the medium 4 to follow the propagation of the shear waves 12.

[0158] According to one example, ultrasonic plane waves are used as sounding waves 14 ([Fig.3]) and the frequency f varies sequentially as the PR parameter of the sounding waves 14.

[0159] According to one example, on the one hand ultrasonic plane waves are used as sounding waves 14 ([Fig.3]), and on the other hand the frequency f as well as the emission angle 0 vary sequentially as PR parameters of the sounding waves 14.

[0160] According to one example, divergent ultrasonic waves are used as sounding waves 14. This implementation is particularly suitable in the case where an ultrasonic probe 2 with a curved profile is used.

[0161] According to one example, focused ultrasonic waves are used as sounding waves 14, which in particular makes it advantageous to observe with precision a relatively small region of interest 4.

[0162] The present disclosure advantageously enables the efficient processing of DTI ultrasonic elastography data to allow for an accurate and reliable estimation of the speed of shear waves 12 propagating in a medium of interest 4. In particular, the disclosure provides for the processing of first DTI data representative of an ultrasonic response 16, of a medium of interest 4, to ultrasonic pulses 8 focused in the medium in combination with sounding waves 16 of which at least one parameter PR is varied over time.

[0163] As previously described, the so-called ultrasonic data averaging technique involves determining ultrasonic data by averaging the ultrasonic responses of a medium of interest in association with several values ​​of the emission angle θ of the sounding waves 14. This technique makes it possible to determine a single estimate of the shear wave velocity 12 for a given position of the medium 4, which does not always allow for a satisfactory characterization of the shear wave velocity, and therefore the rigidity of the medium. If its quality is insufficient, the individual velocity thus obtained cannot be used satisfactorily, which degrades the result of the velocity estimation and hinders the observation of the medium 4. In the case of an imaging application, for example, the image thus obtained may contain unusable areas (or pixels), which would therefore have to be represented, for example, as black pixels.

[0164] Unlike the aforementioned technique for averaging ultrasonic data, the present disclosure relies on a combination of individual velocities VI from which a compound velocity VC can be derived. Thus, instead of averaging ultrasonic data representing ultrasonic responses for different values ​​VL of a PR parameter of the sounding waves 14, the disclosure provides, for example, for averaging individual velocities VI estimated individually for different values ​​VL of a PR parameter of the sounding waves 14.

[0165] Thus, by generating individual velocities VI associated respectively with different values ​​VL of a variable parameter PR, it is advantageous to obtain multiple estimates of shear wave velocities 12 for a given position of the medium 4. It has been observed that the processing resource requirements may be higher than when the ultrasonic data averaging technique is implemented. However, the principle of disclosure advantageously allows for a considerable improvement in the quality of the estimates thus obtained. Disclosure leads to an increase in the size of the usable data, all other things being equal, which may indeed increase resource requirements but, in return, allows for better accuracy and reliability of the estimation.Therefore, by equipping a processing device 20 with suitable processing resources (for example, in the S Y1 ultrasonic system), a relevant compromise can be advantageously achieved between the robustness of the speed estimation and the processing cost, particularly in terms of processing time and resources (memory, computing power, etc.). Such a compromise is possible and adaptable, especially considering current and future developments in the processing capabilities of ultrasonic systems.

[0166] The robustness of the speed estimates can advantageously be maximized by weighting the importance of the individual speeds VI in the calculation of the compound speed VC according to the relevance or quality of the individual speeds VI obtained for each value VL of the parameter PR considered. Different weights K can thus be assigned depending on the value VL of the parameter PR, or even at least one individual speed VI can be excluded (for example, by setting its weight K to zero) so that only certain individual speeds VI are included in the calculation of the compound speed VC.

[0167] By analyzing shear waves 12, it is therefore possible to estimate precisely and reliably the speed of these waves and to deduce the rigidity or elasticity of the medium, for example in tissues of a human or animal body (for example in soft tissues, such as adipose tissue, or muscle fibers).

[0168] As a person skilled in the art will understand, all the embodiments and variants described above, some of which have been deliberately simplified to facilitate explanation, These are merely non-limiting examples of how this disclosure can be implemented. In particular, those skilled in the art may consider any adaptation or combination of the embodiments and variations described above to meet a specific need.

[0169] This disclosure is therefore not limited to the embodiment examples described above but extends in particular to a processing method that would include secondary steps without falling outside the scope of this disclosure. The same would apply to a processing system for implementing such a method.

Claims

Demands

1. Ultrasonic elastography processing method comprising: a) obtaining (S2) first data (DTI) representative of an ultrasonic response (16) of a medium of interest (4), to ultrasonic pulses (8) focused in said medium in combination with sounding waves (14) emitted in said medium sequentially according to distinct values ​​(VL) of at least one parameter (PR) of said sounding waves; b) generating (S4), from the first data respectively for each value (VL) of said at least one parameter, second data (DT2) representative of a propagation of shear waves (12) in the medium of interest under the effect of the ultrasonic pulses; c) estimation (S6), from the second data associated with each value (VL) of said at least one parameter, of an individual speed (VI) representative of the speed of movement of the shear waves for respectively said value;and d) estimation (S8) of at least one speed (VC), called the compound speed, of the shear waves by a combination of the individual speeds.;

2. A method according to claim 1, wherein said at least one parameter of the sounding waves comprises at least one of: - an emission angle (0) through which the sounding waves are emitted in the direction of the medium of interest; and - a frequency (f) through which the sounding waves are emitted in the direction of the medium of interest.

3. A method according to claim 1 or 2, wherein the sounding waves (14) comprise ultrasonic plane waves for sounding the medium of interest.

4. A method according to any one of the preceding claims, wherein the method comprises, prior to obtaining a): e1) formation of shear waves in the medium of interest by focusing ultrasonic pulses; and e2) emission, in the medium of interest, of sounding waves configured sequentially according to distinct values ​​of said at least one parameter to detect the ultrasonic response of the medium of interest for each value.

5. A method according to any one of the preceding claims, wherein the second data generated in b) define, for each value of said at least one parameter, a sequence of images (IM1) representative of the propagation of shear waves caused by ultrasonic pulses in the medium of interest.

6. A method according to any one of the preceding claims, wherein during estimation d), the combination of individual speeds is determined by calculating an average of the individual speeds (V11, V12, VI3) to estimate said at least one compound speed (VC).

7. A method according to claim 6, wherein estimation d) comprises: - assigning weights (Kl, K2, K3), in association with individual speeds (Vl, VI2, VI3), as a function of at least one characteristic of the second data generated respectively for each value (VL1, VI2, VL3) of said at least one parameter; and - estimating said at least one compound speed by calculating the average by weighting the individual speeds according to said associated weights.

8. A method according to claim 7, wherein estimation d) comprises: - determination of spatial variances characterizing respectively the second data associated with each value of said at least one parameter; and - determination, from the spatial variances, of confidence scores associated respectively with the individual speeds, the weight attributed to each individual speed being a function of the associated confidence score.

9. A method according to claim 7 or 8, wherein estimation d) comprises: - if a confidence score associated with second data corresponding to a value of said at least one parameter does not satisfy at least one quality criterion, the weight assigned to the individual speed associated with said value is zero so as to exclude said individual speed from estimation d) of said at least one compound speed.

10. A method according to any one of the preceding claims, wherein the method further comprises: f) estimation, from said at least one compound speed, of a hardness of the medium of interest.

11. A method according to any one of the preceding claims, wherein during estimation d), a plurality of compound velocities (VC) are estimated in different positions of the medium of interest, estimation d) further comprising: - generation, from the compound velocities, of cartographic data (DT3) representative of the compound velocities, and / or of hardnesses estimated from said compound velocities, in respectively the different positions of the medium of interest.

12. A method according to any one of the preceding claims, wherein the method further comprises: - displaying the compound speeds, and / or hardnesses estimated from said compound speeds, in the form of at least one image or map (IM2).

13. A method according to any one of the preceding claims, wherein the method comprises, after a preliminary phase (PHI) during which steps a) to d) are performed for each said distinct value (VL) of said at least one parameter, at least one periodic iteration of a cycle (S20) comprising: - estimation of at least one additional individual speed by reiteration of steps a) to c) for at least one of said values ​​of said at least one parameter; and - estimation of at least one compound speed of the shear waves by reiteration of step d) using the additional individual speed and at least one individual speed estimated during a previous iteration of the cycle and / or during the preliminary phase.

14. Computer program (PG1) comprising instructions for carrying out the steps of a configuration process according to any one of the preceding claims when said program is executed by a computer.

15. Ultrasonic elastography processing device (20) comprising: - a data acquisition module (MD2) configured to obtain first data (DTI) representative of an ultrasonic response (16), of a medium of interest (4), to focused ultrasonic pulses (8) in said medium in combination with sounding waves (14) emitted in said medium sequentially according to distinct values ​​(VL) of at least one parameter (PR) of said sounding waves; - a generation module (MD4) configured to generate, from the first data respectively for each value of said at least one parameter, second data (DT2) representative of a propagation of shear waves (12) in the medium of interest under the effect of ultrasonic pulses; - a first estimation module (MD6) configured to estimate, from the second data associated with each value of said at least one parameter, an individual velocity (VI) representative of the velocity of movement of the shear waves for respectively said value; and - a second estimation module (MD8) configured to estimate at least one velocity (VC), called compound velocity, of the shear waves by a combination of the individual velocities.

16. Processing system (SY2) comprising: - the processing device (20) according to any one of the preceding claims; and - at least one ultrasonic probe (2) configured to focus ultrasonic pulses into said medium and / or emit ultrasonic probing waves into said medium.

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