Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
  • A61B8/48—Diagnostic techniques
  • A61B8/485—Diagnostic techniques involving measuring strain or elastic properties
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
  • A61B8/08—Clinical applications
  • A61B8/0825—Clinical applications for diagnosis of the breast, e.g. mammography
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
  • A61B8/48—Diagnostic techniques
  • A61B8/483—Diagnostic techniques involving the acquisition of a 3D volume of data
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
  • G01S7/52017—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00 particularly adapted to short-range imaging
  • G01S7/52023—Details of receivers
  • G01S7/52036—Details of receivers using analysis of echo signal for target characterisation
  • G01S7/52042—Details of receivers using analysis of echo signal for target characterisation determining elastic properties of the propagation medium or of the reflective target
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
  • A61B8/42—Details of probe positioning or probe attachment to the patient
  • A61B8/4272—Details of probe positioning or probe attachment to the patient involving the acoustic interface between the transducer and the tissue
  • A61B8/4281—Details of probe positioning or probe attachment to the patient involving the acoustic interface between the transducer and the tissue characterised by sound-transmitting media or devices for coupling the transducer to the tissue
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
  • G01S15/88—Sonar systems specially adapted for specific applications
  • G01S15/89—Sonar systems specially adapted for specific applications for mapping or imaging
  • G01S15/8906—Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques
  • G01S15/8993—Three dimensional imaging systems

Definitions

• the present invention relates to a device and a method for measuring the elasticity of a human or animal organ, or more generally any viscoelastic medium presenting an ultrasonic signal after ultrasonic illumination and the consecutive establishment of a representation in two or three elasticity dimensions. It applies in particular, but not exclusively, to the measurement of the elasticity of a human breast, the advantage of this technique is that the pathological nature of the tissues is often related to their elasticity.
• the object of this invention is based on the assumption that the results of measurements by ERM are time-independent solutions of partial differential equations describing with precision the behavior of mechanical waves in a material. viscoelastic (including for longitudinal waves and in a reflective environment). For this, the Young's modulus contained in these equations can be calculated.
• the prior art is also constituted by international patent application No. FR 9903157 which describes an imaging method for observing the propagation of a low frequency shear pulse wave simultaneously at a multitude of points in a diffusing viscoelastic medium.
• ultrasonic compression waves are emitted in this device at an ultra-rapid rate which make it possible to obtain a succession of images of the medium, then the images thus obtained are processed in delayed time by intercorrelation, to determine at each point of each image the movements of the medium during the propagation of the shear wave.
• the invention therefore more particularly aims to remedy the drawbacks of the systems of the prior art.
• a device for measuring the elasticity of a human or animal organ, in particular of a breast, or more generally all viscoelastic media presenting an ultrasonic signal after ultrasonic illumination and the subsequent establishment of a two or three dimensional representation of the elasticity comprising at least one ultrasonic bar (1) comprising a plurality of transducers (12), or the like, an excitation means capable of generating and delivering a low frequency, direct or indirect, stress , a means for acquiring the ultrasonic signals, a means for controlling and processing the data, such as a computer, characterized in that it comprises a scanning means capable of scanning the aforementioned strip (1) to one dimension (1D) or two dimensions
• (2D) in two perpendicular directions, and thus obtain respectively a representation of the elasticity measurement in two (2D) or three dimensions (3D).
• the invention therefore makes it possible to propose a device which makes it possible to obtain a mapping of the elasticity of the medium to be measured in two or three dimensions, by virtue of a relatively simple and inexpensive system relative to existing solutions.
• the ultrasonic strip will include a plurality of transducers intended for the acquisition of the ultrasonic signals.
• the excitation means will consist of a mechanical vibration which may be transverse, longitudinal or more generally a mixture of the two.
• the excitation means could consist of one or more thermal transducers because the rise in temperature generates displacements on the ultrasonic images, either with the transducer (s) used for the acquisition.
• ultrasonic signals or one or more transducers arranged around the viscoelastic medium.
• the excitation means could also consist of internal movements of the human or animal body, such as for example the heartbeat.
• the excitation means will consist of a remote palpation using the radiation pressure, either with the transducer (s) used for the acquisition of the ultrasonic signals or one or more transducers arranged around the viscoelastic medium.
• the device according to the invention will be controlled by at least one control means, for example a computer, a microcomputer or a central unit.
• the ultrasonic bar will be a 1.5 D bar or a star transducer making it possible to focus at a plurality of different elevation points; in this case, the scanning being carried out by ultrasonic focusing.
• a 1.5 D bar is a bar capable of not only focusing along a plane but also in elevation relative to this plane, in the example according to the horizontal plane parallel to the previous one and slightly offset.
• a 0 D echographic array emits along a linear dimension x
• a 1 D array emits along a two-dimensional plane x
• y and finally that 'A 2 D strip, usually constituted by a multitude of ultrasonic transducers of square shape distributed in a 2 D matrix, makes it possible to emit ultrasound in a volume according to the three dimensions x, y and z.
• the space existing between the ultrasonic bar and the aforementioned viscoelastic medium will be constituted at least in part by water or any other element capable of ensuring the free passage of the ultrasonic waves.
• the assembly consisting of the ultrasonic transducers and their on-board electronics will be connected to the control and processing by a very high speed digital link, for example of the LVDS type.
• the device according to the invention will comprise two ultrasonic bars.
• the two bars will be immersed in an airtight container filled with a liquid, for example water.
• the hermetic container will be connected to a rotation means able to rotate said container.
• the hermetic container may comprise a plurality of orifices into which are respectively introduced a mechanical vibrator and / or an ultrasonic transducer.
• the orifices on or in the hermetic housing will be located at 90 ° (degrees) from each other or from one another.
• the device according to the invention will comprise three bars capable respectively of measuring the tissue velocities in the directions y, x and z.
• the invention also relates to a method for measuring the elasticity of a human or animal organ, in particular of a breast, or more generally all viscoelastic media presenting an ultrasonic signal after ultrasonic illumination and the subsequent establishment of a two or three-dimensional representation of the elasticity, comprising at least one ultrasonic bar (1), or the like, an excitation means capable of generating low frequency movements, a means of acquiring ultrasonic signals, a means of controlling and processing data, such as a computer, a scanning means capable of scanning the aforementioned strip (1) in one dimension ( 1D) or two dimensions (2D), and thus respectively obtain a representation of the elasticity measurement in two (2D) or three dimensions (3D), characterized in that it comprises the following stages: - generation of a stress , or signal, low frequency and acquisition of ultrasonic signals, displacement of the bar thanks to the scanning means, in two perpendicular directions, calculation of ultrasound images es, calculation of tissue velocities, inversion of data consisting in recovering the parameters which describe said viscoel
• the step of displacing the bar will be repeated as many times as necessary for the acquisition of all of the ultrasound data before proceeding to the step of calculating the ultrasound images.
• the step of acquiring ultrasonic data also makes it possible to acquire the data necessary for obtaining a conventional ultrasound image, that is to say using a conventional "beamforming".
• the image or images thus obtained constitute information relevant to 2D or 3D on the morphology of the organ studied, this information is completely complementary to the elasticity parameter.
• the second derivatives of the longitudinal component of this velocity in the three orthogonal directions of space can be measured.
• the spatial derivatives of the three components, along the three directions of space, of said velocity can be measured.
• FIG. 1 illustrates the movement of an ultrasound bar of the device according to the invention provided with a simple mechanical scanning means
• FIG. 2 illustrates the movement of an echographic bar of the device according to the invention provided with a double mechanical scanning means
• FIG. 3 illustrates the operation of a 1.5 D bar of the device according to the invention provided with a means of scanning by ultrasonic focusing in elevation;
• FIG. 4 illustrates the device according to the invention provided with a 1.5 or 1.75 D bar, capable of focusing in elevation;
• FIG. 5 illustrates the device according to the invention provided with a star transducer in which the transducers are spatially distributed;
• FIG. 6 illustrates the device according to the invention in the process of measuring the elasticity of the breast of a patient
• FIG. 7 schematically illustrates an embodiment of the device according to the invention.
• This device comprises the usual elements for carrying out elasticity measurements of a human or animal organ, that is to say in particular at least one bar, or probe, ultrasonic comprising a plurality of transducers, electronic equipment capable of ensuring the acquisition of ultrasonic signals, a control and data processing means such as a computer or the like and an excitation means able to generate low frequency displacements.
• the invention relates to the use of a mechanical scanning means which makes it possible to ensure scanning of the above ultrasonic strip.
• This allows, thanks to the method of the invention, to measure parameters which are not accessible with the devices of the prior art, in particular that described in patent N ° FR 9903157.
• the parameters thus obtained are the second derivative of the displacement according to the elevation, that is to say the direction perpendicular to the plane of the image, and the two missing components of the displacement vector.
• any other organ ideally static, can be the subject of a measure of elasticity thanks to the device and to the method according to the present invention provided, of course, to present an ultrasonic signal after it has been illuminated with ultrasonic signals.
• this organ be stationary so as not to disturb the measurement.
• the method according to the invention carries out the steps below in the following chronological order:
• the calculation steps, ie steps 4 to 6 can start as soon as the ultrasonic bar scans the viscoelastic medium, that is to say that these steps take place ideally during the movement of said bar.
• a low frequency signal is transmitted by means of excitation preferably just after the start of the ultrasonic acquisitions.
• This signal has a frequency, f, between 5 Hz and 1000 Hz.
• the low frequency vibration causes propagation in the tissues of the viscoelastic medium of low frequency elastic waves whose propagation depends on the elasticity of the medium.
• the various means that can be used to generate low frequency movements can consist of a mechanical vibration, produced by a vibrator which can be in particular one or more vibrating plates 20, piston (s) and / or bar (s).
• the excitation means able to generate a shear wave could consist of a palpation at a distance using the radiation pressure either with the transducer (s) used for the acquisition of the signals.
• N ultrasonic acquisitions are carried out at a rate 1 / T typically between 100 Hz and 100,000 Hz.
• the acquisition of the ultrasound data is done by emitting with the ultrasonic transducers a pulse brief ultrasound which is reflected by the particles contained in the medium.
• the ultrasonic signal called "speckle" is recorded by the same ultrasonic transducers over a period which can vary between 1 ⁇ s and 10 ms. This operation is repeated a number N of times at the rate 1 / T.
• the scanning consisting in moving said strip will be carried out in three different ways depending on the number and type of ultrasonic strip used.
• the device according to the invention may in particular be equipped with: a single unidirectional ultrasonic bar 1, two ultrasonic bars 5, 6 or a bar then moved along two axes, - a type 1.5 ultrasonic bar
• the echographic bar 1 is moved by a distance between 10 ⁇ m and 10 mm. At least one scan is carried out in one direction. For example we scan in the z direction, made up by plane 2, moving ⁇ z, formed in the figure by the two planes 3 and 4.
• the ultrasound images are constructed using a summation-delay algorithm such as that described in patent No. FR 9903157 previously mentioned or other types of rapid beamforming such as for example the technique in space of spatial frequencies (see article by Lu, J., “2D and 3D High Frame Rate Imaging with Limited Diffraction Beams”, IEEE Trans. Ultrason. Ferroelectr. Freq. Contr., vol. 44, N ° 4, 1997.).
• tissue velocities also called displacement between successive images, tissue velocities or displacements between two successive ultrasonic shots, but not 3
• the data inversion step consists in raising or recovering the parameters which describe the viscoelastic medium. If we consider the linear and isotropic medium, these parameters are two in number. One can choose the shear modulus ⁇ and the compression modulus ⁇ . In practice in soft tissue ⁇ is of the order of Gpa and varies very little. ⁇ is of the order of Kpa. The elasticity or Young's modulus is equal as a first approximation to 3 ⁇ . Thus, it is necessary to determine the shear modulus ⁇ which constitutes the most significant parameter of the viscoelastic medium measured.
• the desired parameter, ⁇ (x, y, z), is obtained by discretizing this equation.
• ⁇ (x, y, z) is obtained by discretizing this equation.
• elastography we generally have one of the three coordinates v x , v y or v z . Suppose it is v x .
• To discretize this equation it is necessary to be able to calculate the second derivatives in the three directions and in time:
• the invention proposes using an assembly or device as shown in FIG. 6.
• This device makes it possible to measure the three components of the tissue velocity vector in the organ studied by successively scanning the medium along three different axes 13, 14 and 15
• the bar 16 makes it possible to measure the tissue velocities in the direction y denoted u y , the bar 17 to measure u x and the bar
• a synchronization system makes it possible to move the transducer 12 between two acquisitions, an acquisition comprising the generation of elastic shear waves and the acquisition of ultrasonic signals.
• the displacement of the system can be carried out for example with a stepping motor or an electrodynamic actuator.
• This acquisition sequence must be reproduced as many times as there is a shot in the image. Using three bars 16, 17, 18 each taking 128 different positions, the system requires 384 separate acquisition sequences. The medium studied can then be segmented into 128 3 voxels 19 of cubic shape. The rate of acquisition of ultrasonic signals is between 100 and 100,000 shots per second.
• the shear waves propagate at 1 m / s and that the main dimension of this medium is 12.8 cm and that the voxels have the dimension 1mm 3 .
• the propagation of the shear wave in such an environment and over a length of 12.8 cm lasts 128 ms.
• 128 ultrasonic shots will have to be taken to follow the propagation of the shear wave.
• the ultrasonic device moves after 500 ms and that a second series of 128 ultrasonic shots is made. If we use three ultrasonic bars to access the three components of the movement, it will take approximately 3 minutes
• the device according to the invention requires at least one ultrasound bar. It also requires electronic equipment for ultrasonic acquisition consisting of ultrasonic transmitters and receivers, digital-analog and analog-to-digital converters, memories, digital and analog transmission lines, etc. To this electronics dedicated to the digitization of ultrasonic signals, there is generally added a processing unit which can for example be a PC type computer associated with a user interface. The elements mentioned in this paragraph are not represented in the various figures but are perfectly known to those skilled in the art. .- 3
• Ultrafast ultrasound imaging techniques generally use only a limited number of ultrasonic emissions to illuminate the entire medium to be imaged. They therefore have the disadvantage of sending less energy into the environment than a standard echographic system. Consequently, the signal-to-noise ratio drops and the dynamic range of the ultrasonic image decreases, which leads to a degradation of the raw ultrasonic data and is reflected in the chain of algorithms to degrade the elasticity measurements in terms of sensitivity and resolution. , etc.
• the device of the invention takes part of the aforementioned electronic equipment near, that is to say typically at a distance of less than 50 centimeters, from the ultrasonic bar with the consequences: the sensitivity of the system,
• the bar is of less importance because the bar is not manipulated. It is motorized.
• the device proposes to place near, or typically less than 50, of the bar the analog part of emission and reception, that is to say the amplifiers of emission and reception, keeping a transmission of analog signals of medium levels between the sensor part and the processing unit.
• the path of the strong analog transmit signals (after amplification) and that of the weak receive signals (before amplification) are reduced, consequently the sensitivity in reception is increased and the transfer of energy to the emission improved.
• the device proposes to place also close, always typically less than 50 cm
• CNA transmission and reception
• LVDS very high speed digital link
• connection between the control / processing means and the sensor part is simplified in terms of number of wires.
• FIG 7 the device according to the invention is shown in a new arrangement.
• two ultrasonic probes 23 and 24 are used, and are immersed in an airtight container 26, filled with water or another suitable liquid.
• the sealed container or housing is capable of rotating, for example by a quarter of a turn, so that the probe 23 can not only scan in the direction X but also in the direction Z.
• the ultrasonic probe 24 scans only in the direction Z
• the acquisition of ultrasonic signals is therefore done in three stages: - scanning in the X and Z directions thanks to the two probes 23 and 24, rotation of the container or hermetic casing 26 for example by a quarter turn, that is 90 degrees,
• mechanical vibrators 25, inserted in orifices present on the periphery or the circumference of the hermetic container 26, can be used to generate low frequency stresses.
• One of the two mechanical vibrators, or the two mechanical vibrators, shown in FIG. 7 can / can be replaced by a hyperthermia probe and / or an ultrasonic transducer used in remote palpation mode.
• the two orifices present in or on the hermetic housing 26 are located 90 degrees from each other, that is to say that the linear mechanical vibrators will be arranged perpendicular relative to each other, so that even after a quarter-turn (90 °) rotation of the container 26, the mechanical vibrators still extend in the same directions, i.e. - say the same lines as before.

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• Heart & Thoracic Surgery (AREA)
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• 2002
  • 2002-09-06 FR FR0211074A patent/FR2844178B1/fr not_active Expired - Fee Related
• 2003
  • 2003-09-02 EP EP03769557A patent/EP1538987B1/fr not_active Expired - Lifetime
  • 2003-09-02 CN CNB038209640A patent/CN100391410C/zh not_active Expired - Lifetime
  • 2003-09-02 AU AU2003278246A patent/AU2003278246A1/en not_active Abandoned
  • 2003-09-02 WO PCT/FR2003/002630 patent/WO2004021888A2/fr not_active Ceased
  • 2003-09-02 US US10/526,417 patent/US7553283B2/en not_active Expired - Fee Related
  • 2003-09-02 ES ES03769557T patent/ES2378817T3/es not_active Expired - Lifetime
  • 2003-09-02 AT AT03769557T patent/ATE537754T1/de active
  • 2003-09-02 JP JP2004533562A patent/JP4405920B2/ja not_active Expired - Fee Related

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