Elastic imaging device and method

Abstract

One aspect of the invention relates to an elastography method implemented by an elastography device, the method comprising:-obtaining a respiratory signal relating to a respiratory activity of a subject; and-acquiring a plurality of measurements of a mechanical property of a region of the body of said subject, said region being part of the liver or spleen of said subject, at a repetition rate of at least 4 measurements per second and over a duration of at least 3 seconds; -extracting at least one subset of measurements from the plurality of measurements, where each subset of measurements among the at least one subset of measurements comprises measurements acquired at the same time of a respiratory cycle, the time of the respiratory cycle being determined from the respiratory signal; -determining a characteristic relating to said mechanical property from said at least one subset of measurements.

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of elastography, for example liver or spleen elastography. More specifically, the present invention relates to an elastography apparatus and an elastography method for accurately determining a measurement of liver stiffness or spleen stiffness of a subject. BACKGROUND

[0002] Measuring liver stiffness (LS) has proven to be a very useful tool to help health care professionals to detect or characterize liver disease or injury and more generally to monitor the liver condition of a subject.

[0007] There are basically two elastography techniques for measuring stiffness: strain imaging and shear wave imaging. In strain imaging, a normal stress is applied to the tissue and the normal strain is measured. The Young's modulus is then determined from the applied normal stress and the measured normal strain. In shear wave imaging, a dynamic stress is applied to the tissue and then a shear wave resulting from the excitation is followed to derive a measurement of the tissue stiffness. Techniques based on shear wave imaging include point shear wave elastography (pSWE), 2D shear wave elastography (SWE) and ID transient elastography (TE). An example of ID transient elastography is FibroScan®, a system used in clinical practice. Vibration-controlled transient elastography (VCTE) used in FibroScan® system.

[0004] Elastography apparatuses based on VCTE typically provide several measurements of the stiffness of a tissue (e.g. liver or spleen) collected at different points in time when the operator triggers the measurement (e.g. by pressing a button to generate a transient displacement). A unique value representative of the stiffness measurement is then derived from these measurements (e.g. the final measurement can be the mean or median of the series of measurements). To obtain a reliable measurement of liver stiffness, it is generally recommended to obtain a series of 10 stiffness measurements.

[0005] Even if this technique works well and provides very satisfactory results, the variability of the series of measurements can be quite large as known.

[0006] There are many factors that can influence the stiffness value of certain organs (e.g. liver or spleen) and thus can cause variability of the stiffness measurements. For example, liver stiffness measurements (LSM) or spleen stiffness measurements (SSM) are influenced by the central venous pressure and more generally by hemodynamic effects as detailed in the article "Liver Stiffness Is Directly Influenced by Central Venous Pressure" by G. Millonig et al., Journal of Hepatology, Volume 52, Issue 2, February 2010, Pages 206-210. SUMMARY

[0007] The inventors of the present application have investigated whether other factors can explain this variability and how to take these factors into account when assessing liver stiffness or spleen stiffness of a subject, e.g. when assessing liver fibrosis or portal hypertension, respectively.

[0008] An aspect of the present application relates to an elastography method, wherein the acquisition of the measurements is synchronized with specific moments of the subject’s respiration.

[0009] An aspect of the present application thus relates to an elastography method implemented by an elastography device, the method comprising:

[0010] - obtaining a respiration signal related to the respiratory activity of a subject; and

[0011] - acquiring a plurality of measurements of a mechanical property of a region of the subject’s body, the region being a part of the subject’s liver or spleen;

[0012] wherein each measurement among at least a subset of the plurality of measurements of the mechanical property is acquired at a same moment of a respective respiration cycle determined from the respiration signal.

[0013] By “mechanical property” is meant any physical property or parameter related to the behavior of a region of the human body when subjected to one or more mechanical stresses. For example, the mechanical property can be a conventional quantity such as stiffness, elasticity, Young’s modulus, shear modulus, shear wave velocity, viscoelasticity, viscosity, ultrasound attenuation, sound speed, backscatter coefficient (BSC), etc. The mechanical property can also be any value derived from one or more of these physical properties or parameters.

[0014] In the following, stiffness is particularly mentioned, but aspects of the present application are applicable to other mechanical properties. Moreover, the liver is particularly mentioned as a region of the body, but aspects of the present application can be applicable to the spleen.

[0015] By “respiration signal” is meant a set of data related to the respiratory activity of a subject. In particular, this set of data can comprise information indicating when the subject is inhaling, exhaling, and the start and end times of the inhalation or exhalation.

[0016] In the example described below, the respiration signal corresponds to a signal representing the amount of time variation on the volume of the subject’s chest acquired using a respiratory belt. It should be understood that the present application is not limited to this signal. For example, the respiration signal can be acquired by an air sensor located near the subject’s nose or mouth, or by analyzing the noise near the subject’s nose or mouth with a microphone to determine whether the subject is inhaling or exhaling. The different sensors described herein for acquiring the respiration signal (air sensor, microphone...) can be broadly referred to as “respiration sensor(s)”.

[0017] "Measurements taken at the same time instant of the respiratory cycle" means measurements taken at similar time instants or time periods in different respiratory cycles. For example, all measurements can be taken at the end of the expiration time period.

[0018] It should be understood that the time instant is determined based on the respiratory signal. For example, when the respiratory signal is a signal representative of the chest diameter of the subject, the end of inspiration can correspond to a local maximum in the respiratory signal and the end of expiration can correspond to a local minimum in the respiratory signal. When the respiratory signal corresponds to information provided by an air sensor, the end of expiration corresponds to the time instant at which no more exhaled air is detected at the outlet of the nose and / or mouth.

[0019] "Each measurement in at least one subset of the plurality of measurements of the mechanical property taken at the same time instant" means that not all measurements have to be taken at the same time in the respiratory cycle. For example, several measurements can be taken during the same respiratory cycle. In this case, there is a first subset of measurements taken at a same first time instant of the respiratory cycle, a second subset of measurements taken at a same second time instant of the respiratory cycle, a third subset of measurements taken at a same third time instant of the respiratory cycle, etc. For example, one can obtain a pair of measurements per respiratory cycle: one at the end of inspiration and one at the end of expiration. Thus, the plurality of measurements comprises a subset of measurements taken at the end of inspiration and a subset of measurements taken at the end of expiration.

[0020] As described in detail below, the inventors have actually determined that there is a variability in the measurements of the mechanical property due to the respiration of the subject. This variability is greatly reduced when the measurements are taken at the same time of the respiratory cycle.

[0021] Moreover, depending on the point in the respiratory cycle at which the measurements are taken, different properties of the body part under examination can be inferred. For example, measurements taken at the end of expiration are more related to fibrosis, while measurements taken at the end of inspiration are more representative of the cardiovascular status. Thus, the time instant can be chosen depending on the targeted diagnostic information.

[0022] A benefit of the elastography method according to one aspect of the application is an increase in the precision of the measured values, and thus an increase in the diagnostic quality of these values. Another benefit is that the elastography method according to one aspect of the application does not require the subject to hold his breath (or even to breathe normally during the process), which can be very uncomfortable or very complex, especially for subjects with obesity problems or respiratory pathologies.

[0023] For example, the respiratory signal can be obtained by a respiratory sensor, and the plurality of measurements of mechanical properties can be acquired by using an elastography probe of an elastography device.

[0024] In one or more embodiments, each of the plurality of measurements of mechanical properties can be acquired at a same instant of the respective respiratory cycle determined from the respiratory signal.

[0025] In other words, in these embodiments, all measurements are made in different respiratory cycles (i.e. at most one measurement per respiratory cycle) and at similar instants of their respective respiratory cycle (e.g. at the end of expiration).

[0026] In one or more embodiments, the plurality of measurements of mechanical properties can be divided into a plurality of subsets of measurements, each subset of measurements comprising measurements acquired at a respective instant of a respiratory cycle, the instants of the respiratory cycle associated with different subsets of measurements being different from each other.

[0027] In these embodiments, several measurements are made at respective specific times during the same respiratory cycle. Thus, the plurality of measurements comprises a first subset of measurements taken at a similar first instant of their respective respiratory cycle (e.g. at the end of inspiration) and a second subset of measurements taken at a similar second instant of their respective respiratory cycle (e.g. at the end of expiration).

[0028] In one or more embodiments, the method can further comprise, for each of the plurality of measurements:

[0029] - detecting an event in the respiratory signal, the event corresponding to the beginning of inspiration, the end of inspiration, the beginning of expiration or the end of expiration; and

[0030] - acquiring the measurement upon detection of the event.

[0031] It will be appreciated that, in case there are several measurements per respiratory cycle, the measurements of the same respiratory cycle can be acquired upon detection of respective events, which can or can not be the same.

[0032] For example, each of the plurality of measurements can be acquired at a respective time corresponding to a time at which a corresponding event related to the cardiac signal is detected.

[0033] In these embodiments, the acquisition of the measurement is synchronized with the detection of the corresponding event.

[0034] Alternatively, each of the plurality of measurements can be acquired at a respective time corresponding to a time at which a corresponding event related to the cardiac signal is detected, with a predefined time offset.

[0035] In these embodiments, the acquisition of the measurements is delayed compared to the detection of the corresponding event.

[0036] In one or more embodiments, the method can further comprise determining a feature related to the mechanical property from the plurality of measurements.

[0037] As mentioned above, the acquisition of the measurements at the same instant(s) of the respiratory cycle reduces the variability between the measurements and thus improves the accuracy of the evaluation of the feature related to the mechanical property from the acquired measurements.

[0038] For example, the feature can be a function of the maximum, minimum, average, standard deviation and / or percentile of the measurements.

[0039] In one or more embodiments, the feature can further be a function of at least one value of the respiratory signal.

[0040] Another aspect of the application relates to an elastography system comprising an electronic unit configured to:

[0041] - obtain a respiratory signal related to the respiratory activity of a subject; and

[0042] - acquire a plurality of measurements of a mechanical property of a region of the subject's body, the region being a part of the subject's liver or spleen;

[0043] wherein each measurement among at least a subset of the plurality of measurements of the mechanical property is acquired at the same instant of the corresponding respiratory cycle determined from the respiratory signal.

[0044] It is noted that aspects of the application can be implemented as part of any elastography technique.

[0045] For example, the above-described method can be implemented in the context of a transient elastography technique, including ARFI (Acoustic Radiation Force Impulse), SWE (Shear Wave Elastography), TE (Transient Elastography) or VCTE (Vibration Controlled Transient Elastography). Thus, in one or several embodiments, the elastography device can comprise:

[0046] - a probe comprising: a protruding portion and at least one ultrasound transducer, the protruding portion to be applied on a subject's body;

[0047] wherein, to determine each measurement of the mechanical property, the electronic unit can be adapted to:

[0048] - deliver a transient low-frequency mechanical pulse to the subject's body via the protruding portion;

[0049] - During the delivery of the mechanical pulse, the ultrasonic transducer is controlled to emit a sequence of ultrasonic pulses, and the echo signal received by the ultrasonic transducer in response is acquired to track how the low-frequency elastic wave induced by the mechanical pulse propagates through the area of ​​the object's body.

[0050] - Determine the corresponding measurement results of the mechanical properties related to the propagation of low-frequency elastic waves.

[0051] Specifically, the elastography device can be a VCTE device. In this case, the probe may also include a low-frequency vibrator arranged to move the protruding portion of the probe, and the delivery of transient low-frequency mechanical pulses may include:

[0052] - The electronic unit controls the low-frequency vibrator to deliver the transient low-frequency mechanical pulses to the body of the object.

[0053] A "transient pulse" refers to a temporary mechanical vibration. The pulse duration, i.e., the activation time, during which there is significant movement of the protruding part (caused by the vibrator in the case of a VCTE device), is followed by a shutdown time during which the protruding part has no or substantially no movement. Substantially no movement means, for example, that during this shutdown time, the displacement of the protruding part that may be caused by the vibrator remains less than 1 / 10 or even 1 / 20 of the peak displacement of the protruding part. For the aforementioned transient pulse, the actuation ratio, equal to the pulse's activation time divided by the sum of that activation time and the subsequent shutdown time, is typically less than 50%, or even less than 20%. The shutdown time is the duration between the end of the activation time and subsequent significant movement of the protruding part (e.g., corresponding to a subsequent transient mechanical pulse) (if any).

[0054] A low-frequency pulse is a pulse with a center frequency below 500 Hz, or even below 250 Hz, but greater than 20 Hz. The center frequency of a pulse can be, for example, the average or median frequency of the spectrum corresponding to the pulse's displacement or displacement velocity, the peak frequency of the main peak of the spectrum, or the average of the -3 dB, -6 dB, or -20 dB cutoff frequencies of the spectrum.

[0055] In one or more embodiments, when the elastography device is a VCTE device, the peak-to-peak amplitude of the displacement of the protruding portion of the probe caused by the low-frequency vibrator can be between 0.2 mm and 10.0 mm, for example, between 0.5 mm and 3.0 mm.

[0056] Another aspect of the present invention relates to an elastography system, which further includes a breathing device configured to acquire respiratory signals.

[0057] The breathing device can use any technology to obtain breathing signals. Moreover, it should be understood that the breathing device can be external to the elastography device or can be part of the elastography device.

[0058] Another aspect of the present invention relates to a non-transitory computer-readable storage medium having stored thereon a computer program including program instructions, the computer program being loadable into a data processing unit and adapted to cause the data processing unit to perform the steps of the elastic imaging method when the computer program is run by the data processing device.

[0059] Other features and benefits of the methods and apparatus disclosed herein will become apparent from the following description of non-limiting embodiments, with reference to the accompanying drawings. Attached Figure Description

[0060] Various aspects of the invention are illustrated by way of example rather than limitation in the accompanying drawings, wherein the same reference numerals denote similar elements, and wherein:

[0061] - Figure 1 This indicates the changes in LSM and respiratory signals over time;

[0062] - Figure 2a , 2b Figures 2 and 2c illustrate several embodiments for acquiring measurement results at a specific moment when a respiratory signal is detected;

[0063] - Figure 3 This is a flowchart describing a method for measuring the mechanical properties of a body region of an object according to an embodiment of the present invention;

[0064] - Figure 4 Examples of elastic imaging devices according to one or more embodiments of the present invention are shown schematically;

[0065] - Figure 5 This indicates that according to one or more embodiments of the present invention, by Figure 4 The sequence of mechanical and ultrasonic pulses emitted by the elastography device;

[0066] - Figure 6 The electronic unit of the elastic imaging device according to one or more embodiments of the present invention is schematically shown. Detailed Implementation

[0067] One or more aspects of the present invention relate to an elastography method and apparatus configured and arranged to provide accurate measurements independent of variables that affect the measurements (e.g., operator experience, patient respiration, or blood pressure).

[0068] The inventors of this invention have investigated the effect of respiration on the values ​​of liver stiffness measurement (LSM) or spleen stiffness measurement (SSM).

[0069] During the respiratory cycle, abdominal pressure changes. These changes are even more pronounced in diaphragmatic breathing (also known as abdominal breathing, the opposite of thoracic breathing). These changes cause variations in LSM or SSM measurements. To better understand these changes, the inventors simultaneously measured both LSM and respiratory signals.

[0070] Figure 1 The result obtained on a single object is shown. Specifically, Figure 1 Representing two curves:

[0071] - Curve 101 represents the LSM signal; and

[0072] - Curve 102 represents the respiratory signal.

[0073] LSM signal 101 was acquired using a VCTE elastography device configured to acquire several liver stiffness measurements per minute, similar to the device presented in patent application EP22305298.6 assigned to the applicant of this patent application.

[0074] In practice, considering that an adult's respiratory rate is on the order of 12 to 20 cycles per minute, which means one cycle every 3 to 5 seconds, with each cycle consisting of one inhalation and one exhalation (where inhalation accounts for about one-third of the respiratory cycle and exhalation accounts for about two-thirds), it is interesting to acquire measurements at a sufficiently high rate (at least 4 measurements per second, for example, 10 measurements per second) to more accurately track changes in the LSM over time, and especially changes during the respiratory cycle. The LSM signal 101 is expressed in kilopascals (kPa).

[0075] A respiratory signal 102 is acquired by measuring the change in chest diameter over time using a breathing belt. The amplitude of this signal 102 depends on the subject's chest diameter and is expressed in arbitrary units. To maximize the correlation between the measurement signal 101 and the respiratory signal 102, the breathing belt can be placed close to the area where the mechanical properties are being measured.

[0076] It should be understood that all observations inferred from these curves also apply to spleen stiffness measurement (SSM) signals. Indeed, LSM and SSM are known to be correlated, and changes in LSM values ​​are reflected in SSM values. Therefore, changes observed in LSM signals that are correlated with hemodynamic changes and changes in abdominal pressure can also be observed in SSM signals. Therefore, aspects of the present invention also apply to SSM signals.

[0077] Return to referenceFigure 1 First, from Figure 1 As can be seen from curves 101 and 102, the LSM value increases during inspiration (i.e., when the respiratory signal 102 increases) and decreases during expiration (i.e., when the respiratory signal 102 decreases). Therefore, the peak value of the LSM signal 101 coincides with the peak value of the respiratory signal 102 in time.

[0078] Furthermore, the peak value (i.e. local maximum value) of the LSM signal 101 depends on the volume of inhaled air (the deeper the inhalation, the higher the LSM peak value), while the minimum value of the LSM signal 101 (at the end of the respiratory cycle or at the beginning of the respiratory cycle) remains relatively stable.

[0079] The relative stability of the minimum values ​​of the LSM signal 101 is more significant because these minimum values ​​are unaffected by the minimum values ​​of the respiratory signal 102. This can be achieved through... Figure 1 As shown in the figure, Figure 1 The two time intervals ΔT1 and ΔT2 represent the period during which the subject consciously holds their breath. The first time interval ΔT1 (approximately 20-25 seconds) is associated with the first average value of the respiratory signal 102. The second time interval ΔT2 (approximately 70-100 seconds) is associated with the second average value of the respiratory signal 102, which is lower than the first value (i.e., the average value of the respiratory signal 102 over time interval ΔT1). It should be noted that the “gap” observed in the respiratory signal 102 during the second time interval ΔT2 (approximately 80 seconds) may be caused by the movement of the breathing band or by the fact that the band has been tightened.

[0080] Two observations can be made:

[0081] - The temporal variation of the LSM signal 101 was lower during the apnea periods ΔT1 and ΔT2 (the peak value was lower than when the subject was breathing); and

[0082] The average value of the LSM signal 101 is approximately the same across the two apnea periods ΔT1 and ΔT2, and roughly corresponds to the value of the LSM signal at the end or beginning of the respiratory cycle.

[0083] Figure 1 It also indicates the third time interval ΔT3 (approximately 40-55 seconds), during which the subject is breathing: the respiratory curve 102 shows rises and falls corresponding to inspiration and expiration, respectively. During this third time interval ΔT3, the numerical changes of local minima are very significant. Conversely, within the same time interval, the numerical changes of local minima of the respiratory signal 102 are very small.

[0084] Generally speaking, the minimum value of the LSM signal 102 can be observed to be within the average value RV (in Figure 1The changes near the value of the respiratory signal 101 are relatively small and unrelated to the changes in the value of the respiratory signal 101. In contrast, the maximum value (i.e., the upward peak) of the LSM signal 102 changes significantly and in a manner related to the respiratory signal 101.

[0085] It should be noted that factors other than respiration can cause changes in the LSM signal, such as hemodynamic effects. In fact, in the unpublished patent application EP24305031.7 assigned to the same applicant, the inventors noted that changes in cardiac signals (particularly components of the CVP waveform) could be observed in the LSM signal.

[0086] Based on these observations, the inventors of this invention concluded that since the liver stiffness measurement (LSM) signal fluctuates synchronously with the respiratory cycle, it is beneficial to acquire liver stiffness measurement results at specific points during respiration (e.g., at the beginning of each inspiration). This synchronization in the acquisition of liver stiffness (LS) measurement results reduces the variability of the measurement results. In fact, from Figure 1 As can be seen, if measurements are taken at the same time of different respiratory cycles, their variability is much lower than if these measurements were performed randomly, as is the case conventionally done with existing elastography devices (in which case one measurement might correspond to a peak, another to a trough, another to the median, etc., and the variability of these measurements could therefore become very high).

[0087] It should be noted that an alternative approach would be to calculate the different measurements taken when the subject is in a state of apnea. However, this involves an unpleasant constraint on the subject (who must hold their breath several times). Furthermore, the average respiratory signal during the apnea period differs depending on when the subject holds their breath (e.g., at the end of inspiration or at the end of expiration), and the values ​​of abdominal pressure also differ. This can affect the measurements of LS (and thus introduce variability into the measurements, which reduces their diagnostic value).

[0088] One aspect of the invention can be advantageously performed while the subject is breathing, thereby making the examination less unpleasant for the subject and allowing for a more accurate assessment of the measurement results.

[0089] In one or more embodiments, individual measurements are acquired during a respiratory cycle, and all measurements are acquired at the same time in their respective respiratory cycles. For example, each measurement may be acquired at the beginning or end of inspiration, or at the beginning or end of expiration.

[0090] It should be noted that, Figure 1On the curve of the respiratory signal 102, inspiration corresponds to the rising portion of curve 102, and expiration corresponds to the falling portion of curve 102. Therefore, the acquisition of measurement results can be triggered when an upward peak (when the measurement result is acquired at the end of inspiration or the beginning of expiration) or a downward peak (when the measurement result is acquired at the end of expiration or the beginning of inspiration) is detected in the curve of the respiratory signal 102.

[0091] Such an embodiment is in Figure 2a and 2b The Chinese side indicated that... Figure 2a and 2b Indicate Figure 1 A simplified schematic version of curves 101 and 102. (e.g.) Figure 1 As shown, curve 101 represents the LSM time signal, and curve 102 represents the respiratory time signal.

[0092] As mentioned above, the phase in which the respiratory signal 102 increases corresponds to inspiration ( Figure 2a and 2b The “Insp” in the text, and the phase in which the respiratory signal 102 decreases corresponds to expiration ( Figure 2a and 2b (Exp in the text).

[0093] exist Figure 2a In the example, measurement results E1, E2, E3, and E4 are acquired at different times t1, t2, t3, and t4 corresponding to the end of inspiration (or approximately equivalently at the time corresponding to the start of expiration). In this example, the detection of the upward peak (i.e., local maximum) in the curve of the respiratory signal 102 thus triggers the acquisition of the corresponding LS measurement results E1, E2, E3, and E4.

[0094] In some embodiments, measurements are acquired at each upward peak in the respiratory signal 102. However, this is not mandatory, and it is possible that measurements are not acquired at certain upward peaks. Figure 2a This is particularly true in the example shown, where no measurements are taken during the intermediate peak between times t3 and t4. For example, it is possible that the elastography device is not ready to acquire measurements at certain peaks in the respiratory signal.

[0095] exist Figure 2b In the example, measurements E'1, E'2, E'3, and E'4 are acquired at different times t'1, t'2, t'3, and t'4 corresponding to the start of inspiration (or approximately equivalently at the time corresponding to the end of expiration). In this example, the detection of a downward peak (i.e., a local minimum) in the curve of the respiratory signal 102 thus triggers the acquisition of the corresponding LS measurements E'1, E'2, E'3, and E'4.

[0096] In some embodiments, measurements are acquired at each downward peak in the respiratory signal 102. However, this is not mandatory, and it is possible that measurements are not acquired at certain downward peaks.

[0097] The detection of upward or downward peaks in a signal is known and will not be described in further detail here. For example, upward or downward peaks can be detected by detecting the rising or falling edge of the signal to reach a predefined threshold.

[0098] It should be noted that measurements can be taken at any time other than the end or beginning of expiration or inspiration. For example, measurements can be taken at the end of a predefined time offset period after the peak (upward or downward).

[0099] Furthermore, it should be noted that in the embodiments, the derived measurement result can be calculated based on the acquired LS measurement results and the corresponding respiratory signal values. For example, the derived measurement result can be equal to E. i / V i V i Corresponding to the measurement result E i The value of the respiratory signal at that time, or equal to E i / V, where V is the respiratory signal relative to the measurement result E i Average values ​​over the associated time window, etc.

[0100] In an alternative embodiment, several measurements may be acquired during the same respiratory signal. For example, two measurements may be acquired during a respiratory cycle: one at the end of expiration (or the beginning of inspiration) of the respiratory cycle, and another at the end of inspiration (or the beginning of expiration) of the respiratory cycle.

[0101] Such an embodiment is in Figure 2c The text appears to be a mix of Chinese characters and symbols, possibly representing a corrupted or incomplete sentence. A direct translation wouldn't be meaningful without further context. Figure 2b In the example, at different times t 11 t 12 t 21 t 22 E of the collected measurement results 11 E 12 E 21 E 22 At the corresponding time t at the end of two consecutive inhalations. 11 and t 21 (Or roughly equivalently, collect E at the beginning of two consecutive exhalations) 11 and E 21 At the corresponding time t corresponding to the start of two consecutive inhalations. 12 and t 22 (Or roughly equivalently, collect E at the end of two consecutive exhalations) 12and E 22 .

[0102] Therefore, the amplitude of the LSM signal (i.e., the difference between the maximum and minimum values) can be estimated over several respiratory cycles. For example, these measurements can then be used to determine a value representing the amplitude of the LSM signal. Figure 2c In the example, two estimates of the magnitude are obtained: a1 = E 11 –E 12 and a2 = E 21 –E 22 It should be understood that the estimated number (i.e., the number of respiratory cycles during which measurements are taken) can be greater than 2, for example, about five, ten, or even more than ten. The average or percentile of all the estimates obtained can then be calculated, for example, to have a single value representing the amplitude of the LSM signal 101.

[0103] Instead of using the LS measurement result itself, a normalized value can be used when the respiratory signal value is considered during measurement acquisition. For example, if V ij Indicates the measurement result E. ij If the value of respiratory signal 102 is given, then the above estimate can be replaced with:

[0104] a1 = E 11 / V 11 –E 12 / V 12 and a2 = E 21 / V 21 –E 22 / V 22

[0105] or:

[0106] a1=(E 11 –E 12 ) / (V 11 –V 12 ) and a2=(E 21 –E 22 ) / (V 21 –V 22 )

[0107] or E 11 E 12 E 21 E 22 V 11 V 12 V 21 and V 22 Another function of .

[0108] It should be understood that, depending on the desired information and the envisioned medical application, a single measurement may be collected during the respiratory cycle (always at the same time of the cardiac cycle), or several measurements may be collected during the same respiratory cycle.

[0109] In fact, refer to again Figure 1 The observed curves 101 and 102 indicate that the upward peak in LSM signal 101 is mainly affected by abdominal pressure, while the local minimum (or low plateau) of LSM signal 101 may be more related to the stiffness of the parenchyma (and therefore more related to the level of fibrosis).

[0110] Furthermore, this means that an LSM signal can be viewed as a combination of two components:

[0111] - The "dynamic" component reflects pressure changes within the body part being measured for stiffness and the effect of respiration on the signal; and

[0112] - The "resting" component is unaffected by these factors, especially by breathing.

[0113] The resting component reflects a more static contribution from the liver parenchyma and is considered to be more associated with fibrosis compared to the dynamic component. This resting component typically corresponds to... Figure 1 The signal components near the value RV in the value.

[0114] Furthermore, it has been observed that when the probe is tilted relative to a position perpendicular to the surface of the object on which it is applied, the resulting measurements are often higher than the true values. Therefore, a lack of probe perpendicularity to the object leads to overestimation of the measurements. The resting component also eliminates or reduces overestimation associated with probe perpendicularity.

[0115] The dynamic component of the signal reflects changes due to respiration and the effects of blood pressure due to hemodynamic and cardiovascular characteristics, while the resting component is mainly associated with fibrosis.

[0116] Therefore, if LS measurements are used as part of a fibrosis diagnosis, it may be of interest to trigger the acquisition of each measurement at the low peak of the LSM signal, i.e., at the end of expiration (or at the beginning of inspiration). This corresponds to Figure 2a Examples.

[0117] If LS measurements are used as part of the diagnosis of cardiovascular disease, it may be of interest to trigger the acquisition of each measurement at the peak of the LSM signal, i.e., at the beginning of expiration (or at the end of inspiration). This corresponds to Figure 2b Examples.

[0118] If the objective is to assess hemodynamic and cardiovascular changes, it might be of interest to acquire two measurements over multiple respiratory cycles: one at the peak of the LSM signal and one at the trough, to calculate the difference between these two measurements and thus estimate the amplitude of the LSM signal. This corresponds to... Figure 2c Examples.

[0119] It should be understood that other applications and implementations may be considered.

[0120] Figure 3 A flowchart illustrating a method for determining the measurement results of a portion of the spleen or liver of an object, in one embodiment of the present invention. Figure 3 The method can be implemented by an electronic unit of an elastography apparatus, or by an electronic unit of a computing device external to the elastography apparatus and configured to receive data from the elastography apparatus. The electronic unit may include one or more electronic circuits to perform its functions. The one or more electronic circuits may include a processor (e.g., a microprocessor) and memory encoded with instructions that, when executed by the processor, perform the functions of the electronic unit. In an embodiment, the electronic unit may be configured to perform… Figure 3 The method shown.

[0121] according to Figure 3 In one embodiment, multiple measurements of mechanical properties are determined at specific moments in the respiratory cycle. These determined measurements are then used to identify characteristics associated with the mechanical properties.

[0122] In the following text, mechanical properties correspond to tissue stiffness, and more specifically, liver stiffness. It should be understood that any other mechanical property can be measured, such as elasticity, Young's modulus, shear modulus, shear wave velocity, viscoelasticity, viscosity, or any composite biomarker derived (or combined) from one or more of the prior physical quantities. Furthermore, it should be understood that the present invention can also be applied to the spleen.

[0123] The subject's respiratory signal is obtained at step 210.

[0124] Respiratory signals can be acquired, for example, via a breathing belt or a breathing sensor, or any other technique that enables the detection of specific moments in a subject's respiratory cycle. In embodiments, the respiratory signals are provided to the electronic unit of the elastography apparatus or to a remote device communicating with the elastography apparatus.

[0125] In optional step 220, one or more conditions for the electronic unit to enter a measurement mode can be determined. This measurement mode may correspond to a mode in which the electronic unit is ready to begin determining measurement results. When the electronic unit is not in a measurement mode, no measurement is performed.

[0126] One or more conditions may include, for example:

[0127] - Regarding the condition of whether the probe's position and orientation are appropriate, i.e., whether the probe is correctly positioned relative to the body area from which the mechanical properties are to be measured. U.S. Patent Application US17 / 695,053, assigned to the applicant, details examples of determining such conditions; and / or

[0128] - Conditions imposed regarding whether the tip of the probe is properly pressed against the body of the object.

[0129] In optional step 230, the electronic unit can determine whether all the conditions of step 220 are met. When at least one condition is not met or is met (step 220, arrow "N"), the electronic unit does not enter the measurement mode and cannot begin acquiring the measurement result E. k If all conditions are met or satisfied (step 220, arrow "Y"), the electronic unit proceeds to measurement mode. Once in measurement mode, the electronic unit can monitor for events related to the ECG signal.

[0130] In step 240, a specific moment (or instant or time) of the respiratory cycle in the respiratory signal is detected by the electronic unit. As mentioned above, the specific moment may correspond to an upward or downward peak in the respiratory signal. Detection of this moment 240 results in the acquisition or extraction (step 250) of a corresponding measurement result E of the mechanical properties. k As detailed above, according to the embodiments, there may be one measurement per respiratory cycle, or several measurements per respiratory cycle. It should be understood that it is not mandatory to collect measurement results for every single respiratory cycle. Measurement results may not be collected during certain cycles. At least one measurement result E can be determined (step 250) by any elastography technique. k .

[0131] In step 260, at least one feature representing the mechanical properties of the object can be determined based on the measurement results obtained in step 250.

[0132] A characteristic representing a mechanical property can be a single value determined based on the obtained measurement results. For example, a characteristic can be a minimum, maximum, given percentile, mean, standard deviation, or a function of any statistical indicator of the obtained measurement results. A characteristic can also be a function of a combination of at least two statistical indicators.

[0133] In an embodiment, a characteristic representing the mechanical properties can be determined based on the obtained measurement results and based on additional values ​​(e.g., based on at least one value obtained from the respiratory signal). For example, the characteristic can be determined based on the obtained measurement results and the value of the respiratory signal at the time when the measurement results were acquired. In particular, the characteristic can be a function of the minimum, maximum, given percentile, average, standard deviation, or any statistical indicator of the values ​​derived from the measurement results of the mechanical properties and the value of the respiratory signal.

[0134] As described above, this feature can provide more accurate information related to mechanical properties than conventional methods. In current elastography techniques, several (e.g., 10) measurements of stiffness are determined at corresponding moments that can correspond to extremely different times in the respiratory cycle and thus to extremely different stiffness values. Based on these measurements, characteristics representing stiffness (e.g., the average or median of the measurements) are calculated without considering this variability. For example, this variability is reduced by considering measurements that are always taken at the same (at least approximately) time in the respiratory cycle.

[0135] When several measurements are collected during each respiratory cycle, median values ​​can be calculated from these measurements, with each median value corresponding to one respiratory cycle. For example, when two values ​​are collected at the low and high points of the same respiratory cycle, the median value can be the absolute value of the difference between the two measurements. A feature can be a single value determined based on the obtained median values. For example, a feature can be the minimum, maximum, given percentile, mean, standard deviation, or a function of any statistical indicator of the obtained median values. A feature can also be a function of a combination of at least two statistical indicators.

[0136] At optional step 270, the features identified in step 260 may be displayed on the screen of the elastography device and / or a device communicating with the elastography device for use by a medical practitioner. Alternatively or additionally, other information may be displayed. For example, a single respiratory signal and an elastography graph may be displayed.

[0137] It should be understood that the measurement results of the mechanical properties in step 250 can be obtained using any elastography technique. In particular, it can be obtained using an elastography device employing vibration-controlled transient elastography (VCTE) technology (such as...). Figure 4 The device described herein is used to collect measurement results of mechanical properties. However, it should be noted that the present invention is not limited to this technique.

[0138] Figure 4The elastic imaging device 1 includes a probe 2, which includes a handheld probe housing 3 (which forms the body of the probe) and a protrusion extending from the housing 3. The protrusion can be applied against the body 8 of an object to deliver mechanical pulses to it and to transmit and acquire ultrasonic (U / S) emissions.

[0139] exist Figure 4 In the example, the protruding part is the tip 4, such as a cylindrical tip (with a circular transducer 6 at its end).

[0140] Furthermore, in other embodiments, the protruding portion may be an ultrasound head (located at the end of the probe) comprising an array (e.g., a linear array of U / S transducers). In this regard, it can be noted that the proposed technique can be used with single-element ultrasound transducers or multi-element ultrasound transducers (such as arrays of U / S transducers, e.g., linear, convex, or phased array ultrasound probes). While single-element ultrasound transducers are suitable for displaying A-mode and M-mode ultrasound imaging, multi-element ultrasound transducers can also display B-mode images that allow for easier localization of the tissue being measured. In the case of multi-element ultrasound transducers, at least one of the beam-shaped ultrasound lines is used to track how the mechanical pulse propagates. For this purpose, it is advantageous to use a centrally beam-shaped ultrasound line (aligned with the probe axis) for symmetry reasons.

[0141] The probe 2 also includes a low-frequency vibrator 5 and a U / S transducer 6 fixed at the end of the tip 4. Here, the U / S transducer 6 functions as both an ultrasonic transmitter and an ultrasonic receiver (optionally). Furthermore, in other embodiments, the probe may include a U / S transmitter and a U / S receiver that are distinct from each other. Here, the U / S transducer 6 is arranged on the axis z of the vibrator. Furthermore, in other embodiments, the U / S transducer may be located at other positions on the probe, not necessarily on the axis of the vibrator.

[0142] Tip 4 is actuated by a low-frequency vibrator 5. Here, vibrator 5 is arranged to move tip 4 relative to probe housing 3. Vibrator 5 is arranged to move shaft 4', the end of shaft 4' forming the tip 4 of the probe. Furthermore, in other embodiments, the probe can be an inertial probe. In such an inertial probe, the tip, or more generally the protrusion of the probe, can be engaged with the probe housing without movement relative to the probe housing, and then the vibrator is arranged to move a mass within the housing to move the entire probe toward the tissue and backward (by means of a recoil effect).

[0143] Vibrator 5 is a low-frequency vibrator because it moves its tip at a center average frequency of less than 500 Hz or even less than 100 Hz (as opposed to ultrasonic emission or echo signals, whose center frequency is typically above 1 MHz, for example, between 1 and 5 MHz). The vibrator is a low-frequency electromechanical actuator, such as one with one or more coils and magnets, like a loudspeaker actuator.

[0144] In this device 1, the vibrator 5 is rotationally symmetrical about its axis, which coincides with the probe axis z. When the vibrator 5 vibrates, it causes a primarily longitudinal displacement parallel to its axis. The shaft 4' is centered on the axis z, and the vibrator 5 is arranged such that this shaft moves along the axis z.

[0145] In practice, the displacement of the ultrasonic transducer 6 caused by the vibrator 5 has an interpeak amplitude between 0.2 mm and 10.0 mm, and in one embodiment, between 0.5 mm and 3.0 mm.

[0146] The probe 2 includes a displacement sensor 11, which is arranged to output a measurement signal Sd representing the displacement of the ultrasonic transducer 6. In this embodiment, the measurement signal Sd represents the displacement of the ultrasonic transducer 6 relative to the probe housing 3. A portion of the displacement sensor 11 is fixed to the aforementioned shaft 4', while another portion of the sensor is assembled within the probe and does not move relative to the housing 3. The displacement sensor 11 can be a Hall effect sensor, an inductive displacement sensor, or any other suitable sensor.

[0147] In one or more embodiments, the device 1 may further include at least one breathing sensor 12, which is placed on or near the body of the subject (e.g., in the case of a chest pressure sensor) to record the subject's breathing activities and obtain the subject's breathing signals.

[0148] It should be noted that, alternatively, the respiratory sensor 12 may not be part of the device 1, but may be connected to the device 1, for example, via one or more wires, so that the device 1 can receive signals related to the breathing activity of the subject. The device 1 may, for example, receive and process data collected by the sensor to obtain a respiratory signal, or alternatively, directly receive the subject's respiratory signal.

[0149] Probe 2 is operatively connected to a central unit 7, which has a computer architecture (e.g., a laptop computer, smartphone, or dedicated electronics arranged to control and interface with the probe and process the acquired signals). The central unit 7 includes at least a memory and a processor. At least one memory is encoded with machine-readable instructions for performing one or more functions of the central unit 7 when executed by the processor. The central unit 7 may also include a display for displaying information such as curves representing the change in the mechanical properties of region 80 over time during examination of the object, one or more elastograms, one or more features associated with the mechanical properties (e.g., resting or dynamic values), or other information (e.g., LSM signals). The display and graphical user interface can be controlled by the processing circuitry of the central unit 7 to display visual information to the operator or prompt the operator of the elastography device 1 to initiate one or more actions or commands. For example, the graphical user interface can be controlled by the central unit 7 to prompt the operator of the elastography device 1 to initiate or begin elastography measurements of the mechanical properties of patient organs associated with respiratory signals obtained using the respiratory sensor 12 (e.g., liver stiffness measurement or spleen stiffness measurement). In one or more embodiments, the processing circuitry of the central unit 7 may enable a graphical user interface to display a menu that allows an operator to select and perform specific types of measurements, such as measurements of mechanical properties determined with or without a respiratory signal, and / or measurements of resting and / or dynamic components or values ​​associated with mechanical properties, to provide different types of diagnoses. The processing circuitry of the central unit 7 may enable a graphical user interface to display measurement results, such as measurements of mechanical properties determined with or without a respiratory signal, and / or measurements of resting and / or dynamic components or values ​​associated with mechanical properties. The central unit 7 also includes at least one user interface, such as a keyboard, mouse, one or more buttons, and / or a touchscreen, for inputting one or more data and / or information and / or parameters. As a non-limiting example, additional parameters may include the patient's or subject's age, height, weight, body mass index (BMI), and fat mass index.

[0150] The probe can be connected to the central unit 7 via connecting cable 9 or via a wireless link. Similarly, the breathing sensor can be connected to the central unit 7 via connecting cable 13 or via a wireless link.

[0151] The central unit 7 may also include an electronic unit 10 connected to the vibrator 5, the U / S transducer 6, and the respiration sensor 12, and configured (e.g., programmed via instructions stored in a memory) to control the elastography device 1, causing it to operate to acquire (or “determine”) multiple measurements of the mechanical properties of region 80 of the body, to receive and process data from the respiration sensor 12, and to implement…Figure 3 The electronic unit 10 can be configured to receive signals acquired by the respiratory sensor 12.

[0152] In one or more embodiments, multiple mechanical measurements can be acquired in response to manual triggering by an operator. For example, such manual triggering can be achieved by actuating a push-button switch disposed on the probe housing 3 or by actuating a foot switch.

[0153] like Figure 5 As shown, to obtain measurement results of mechanical properties, the electronic unit 10 can be configured to control the low-frequency vibrator 5 to deliver multiple mechanical pulses MP to the body 8 of the object, each pulse MP being a transient low-frequency mechanical pulse. Each mechanical pulse MP corresponds to the instantaneous displacement d of axis 4' along the axis z pointing towards the body of the object (see...). Figure 4 The displacement d of shaft 4' caused by the vibrator can, for example, correspond to one period of a sine curve having a duration T between 5 ms and 50 ms (i.e., a frequency between 20 Hz and 200 Hz).

[0154] The displacement d of shaft 4' caused by vibrator 5 has an interpeak amplitude A between 0.2 mm and 10.0 mm, and in one embodiment between 0.5 mm and 3.0 mm.

[0155] When an elastography device is configured to characterize a patient’s liver, the center frequency of each mechanical pulse MP can be between 10 Hz and 500 Hz, for example, between 50 Hz and 200 Hz (typically 50 Hz in this case).

[0156] like Figure 5 As shown, for each mechanical pulse MP, the electronic unit 10 controls the U / S (ultrasound) transducer 6 (such as a U / S pulse generator 41 with a U / S front end 40) to emit a sequence Seq of ultrasonic pulses USP and acquire the echo signal received by the U / S transducer 6 in response to track how the mechanical pulse MP propagates through the detection area 80 of the body 8 of the object located in front of the tip 4 of the probe.

[0157] For this sequence Seq, the center frequency of each ultrasound pulse USP includes, for example, between 0.5 and 10.0 MHz. The ultrasound pulses of the sequence Seq can be transmitted one at a time, with two consecutive pulses separated by a pulse repetition period RP, which is typically between 0.1 ms and 2 ms (corresponding to a pulse repetition frequency between 0.5 kHz and 10 kHz), and in embodiments between 0.3 ms and 1 ms. The ultrasound pulses USP of the above-described sequence Seq can also be transmitted in groups, for example, by transmitting two pulses as a group (to calculate the correlation between two corresponding echo signals). The two pulses in each group can be separated by a duration between 50 microseconds and 200 microseconds, while the pulse group itself is separated by a longer duration, for example, longer than 0.2 ms or 0.5 ms. It should be understood that other transmission sequences are also contemplated in various embodiments.

[0158] The total duration of the U / S pulse sequence Seq can be between 25 ms and 200 ms. This duration can be selected based on the shear wave frequency, the slower propagation velocity of the elastic wave, and the depth of the region to be observed. For example, for a shear wave frequency of 50 Hz, a depth of 80 mm, and a propagation velocity of 1 m / s (typical for shear waves in the liver of a subject), the sequence could have a duration of 100 ms.

[0159] Regarding the echo signals acquired to track the propagation of the considered mechanical pulses, each of them is formed by a signal received by the U / S transducer 6 over time t after one of the emitted U / S pulses USP. More precisely, it is the signal received within a given time window, which begins after the emission and has a given duration.

[0160] In the embodiments described herein, for each mechanical pulse MP, electronic unit 10 determines tissue strain data representing tissue strain within region 80, which is a function of time t and depth z within region 80. The tissue strain data is determined based on acquired echo signals to track how the mechanical pulse MP propagates through region 80. When graphically represented as a function of time and depth, such tissue strain data forms an elasticity map, from which measurements of mechanical properties (e.g., tissue stiffness) can be determined.

[0161] Tissue strain data can be determined from echo signals using related techniques or another pattern-matching algorithm to determine how parts of the tissue move under the influence of elastic waves passing through them (elastic waves are generated by periodic mechanical vibrations delivered by the system). For example, for each pair of two consecutively received echo signals, the two echo signals are correlated with each other, which makes it possible to determine the tissue displacement (i.e., the tissue displacement occurring between two U / S pulses) based on depth and at a given time.

[0162] As described above, for each mechanical pulse MP, or at least for several of them, corresponding tissue strain data can be obtained, and the corresponding measurements of the mechanical properties of region 80 can be determined. Figure 5 E1, E k-1 E k E k+1 Each determined measurement result E n It can be associated with the corresponding time t representing the moment when the measurement is performed. n Related. For example, as in Figure 5 In the embodiment shown in the figure, each measurement result E n The corresponding time t is equal to the time when the corresponding mechanical pulse MP has been emitted. n Related. Other embodiments are possible. For example, each measurement result E n It can be compared with the corresponding time t n Related, the corresponding time t n This is equal to the time of acquiring the last echo signal in response to the transmission of the corresponding sequence Seq of the U / S pulse USP. Alternatively, each measurement result E n The result E can be determined by equality. n The corresponding time t after the corresponding tissue strain data is determined. n Related. It should be noted that the time t obtained through all these embodiments... n The values ​​of are very small and have almost no effect on the interpretation of the obtained signal E(t).

[0163] The mechanical properties of tissues associated with low-frequency shear wave propagation can be quantities related to tissue stiffness, such as the shear wave propagation velocity V. s The shear modulus or Young's modulus E of the tissue (which can be derived from the slope of the fringes identified in the elasticity diagram, or from the change in the flight time of the measurement pulse as a function of depth). It can also be a quantity related to the attenuation of low-frequency shear waves in the tissue, such as viscosity.

[0164] As mentioned above, it should be noted that even Figure 4 The elastography device represented in the text is a VCTE device, and aspects of the present invention can be extended to any type of elastography device. In particular, the present invention can be applied to other TE (transient elastography) devices, such as those implementing ARFI (acoustic force pulse) or SWE (shear wave elastography) techniques. In ARFI and SWE, unlike VCTE, the longitudinally moving shear wave is not generated by an external vibrator. Instead, in ARFI, pressure radiation generated by ultrasound is focused on the region of interest. The radiated pressure generates a laterally moving shear wave, which is tracked outside the region of interest using an ultrasound tracking pulse.

[0165] It should be noted that in the above reference Figure 2a and 2b In the described embodiments, there are no constraints regarding the rate at which measurements are acquired by the elastography device. In practice, measurements are acquired at a frequency of at most one measurement per respiratory cycle at specific times of the respiratory cycle (it should be understood that measurements may not be acquired in some cycles).

[0166] Refer to the above Figure 2c In the described embodiments, the elastography device is preferably capable of acquiring at least two measurements per respiratory cycle (even though this constraint can be relieved, for example, by considering a pair of values ​​including the value at the end of inspiration in the respiratory cycle and the value at the end of expiration in the next respiratory cycle). Given that the average duration of an adult respiratory cycle is approximately 3 seconds, this means the elastography device is configured to acquire a measurement every 1.5 seconds.

[0167] It should be understood that, for all embodiments, the elastography device can be configured to acquire measurement results at a much higher frequency, such as several measurement results per second. In particular, the elastography device can be configured to acquire at least four measurement results per second, such as five, ten, or even more than ten measurement results per second. An example of such an elastography device is provided, for example, in patent EP 4 245 224 assigned to the applicant.

[0168] This high-acquisition-rate elastic imaging device enables, for example, the acquisition of signals representing changes in measurements of mechanical properties, such as... Figure 1 The LSM signal 101 shown is a signal that represents the change of mechanical properties over time, including at least a portion of the measurement results of the determined mechanical properties.

[0169] Using such an elastography device, measurements can be acquired, for example, continuously (i.e., at a predefined rate, such as 5 or 10 measurements per second), to obtain a signal representing the time variation in the measurements indicating mechanical properties, and to determine the measurement corresponding to a specific moment in the respiratory cycle based on the obtained signal (i.e., Figure 3 (The measurement results of step 250). In these embodiments, Figure 3 Step 250 includes extracting one or more subsets of measurements from among the multiple measurements acquired (or from signals representing time variations of measurements of mechanical properties), each subset of measurements being associated with a corresponding moment in the respiratory cycle (i.e., all measurements from the same subset of measurements are acquired at the same time in the corresponding respiratory cycle).

[0170] Figure 6 This schematically represents the configuration for implementation.Figure 3 An example of the electronic unit 10 of the elastic imaging device of the method.

[0171] Electronic unit 10 may form at least part of a computer and includes non-transitory memory 601 for storing program instructions that may be loaded into circuit computer 602 (e.g., microelectronic circuits or circuit systems) and, when executed by computer circuit 602, are adapted to cause computer circuit 602 to perform one or more steps of the methods described herein or one or more functions of the apparatus described herein.

[0172] The memory 601 may also store data and useful information for performing the steps of the methods described herein. The circuit 602 may be, for example:

[0173] - A processor or processing unit adapted to interpret instructions in a computer language, the processor or processing unit may include memory containing the instructions, and may be associated with or attached to memory containing the instructions, or

[0174] - A combination of a processor / processing unit and memory, wherein the processor or processing unit is adapted to interpret instructions of a computer language, and the memory includes said instructions, or

[0175] - Electronic card, wherein the steps of the invention are described within silicon, or

[0176] - Programmable electronic chips, such as FPGA chips (used for field-programmable gate arrays).

[0177] The electronic unit 10 also includes an input interface 603 for receiving data related to LS measurement results and data related to respiratory signals, and for providing... Figure 3 The output interface 604 of at least one feature determined in step 260.

[0178] Optionally, the computer circuit 602 can be connected to a screen and can be configured to control the screen and the graphical user interface to make the graphical user interface display predetermined information, such as, for example, a curve of a breathing signal, values ​​of determined characteristics, etc.

[0179] When interpreting the specification and its related claims, expressions such as “comprising,” “including,” “incorporated,” “containing,” “is,” and “have” should be interpreted in a non-exclusive manner, that is, to allow the presence of other items or components not explicitly defined. References to the singular should also be interpreted as references to the plural, and vice versa.

[0180] Those skilled in the art will readily understand that the various parameters disclosed in the specification can be modified and the various disclosed embodiments can be combined without departing from the scope of the invention.

Claims

1. An elastic imaging method implemented by an elastic imaging device, the method comprising: - Obtain respiratory signals related to the object's respiratory activity; as well as - Collect multiple measurements of the mechanical properties of a region of the body of the object, which is part of the liver or spleen of the object, at a repetition rate of at least 4 times per second and for a duration of at least 3 seconds; - Extract at least one subset of measurement results from the plurality of measurement results, wherein each subset of measurement results includes measurement results collected at the same time during the respiratory cycle, the time of which is determined based on the respiratory signal; - Determine the features related to the mechanical properties based on the at least one subset of the measurement results.

2. The elastic imaging method according to claim 1, wherein, The characteristic associated with the mechanical property is a function of the maximum, minimum, average, standard deviation, and / or percentile of the measurement results in the at least one subset of measurement results.

3. The elastic imaging method according to any one of the preceding claims, wherein, The time of the respiratory signal corresponds to the start of inhalation, the end of inhalation, the start of exhalation, or the end of exhalation.

4. The elastic imaging method according to any one of the preceding claims, wherein, The at least one subset of measurement results includes a first subset of measurement results collected at a first moment of the respiratory cycle and a second subset of measurement results collected at a second moment of the respiratory cycle, wherein the first moment of the respiratory cycle and the second moment of the respiratory cycle are different from each other.

5. The elastic imaging method according to any one of the preceding claims, wherein, The feature is also a function of at least one value of the respiratory signal.

6. An elastic imaging system, comprising an electronic unit, the electronic unit being configured to: - Obtain respiratory signals related to the object's respiratory activity; as well as - Collect multiple measurements of the mechanical properties of a region of the body of the object, which is part of the liver or spleen of the object, at a repetition rate of at least 4 times per second and for a duration of at least 3 seconds; - Extract at least one subset of measurement results from the plurality of measurement results, wherein each subset of measurement results includes measurement results collected at the same time during the respiratory cycle, the time of which is determined based on the respiratory signal; - Determine the features related to the mechanical properties based on the at least one subset of the measurement results.

7. The elastography system of claim 6 further includes a breathing device configured to acquire the breathing signal.

8. A non-transitory computer-readable storage medium having a computer program thereon containing program instructions, the computer program being loadable into a data processing unit, and when the computer program is run by the data processing device, the computer program being adapted to cause the data processing unit to perform the steps according to any one of claims 1 to 5.

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