Ultrasound on-probe vibration systems, methods and devices for elastography and viscoelastography medical imaging

Abstract

Systems, methods, and devices are provided for inducing acoustic vibrations in the human body for medical imaging purposes, such as elastography and viscoelastography. The method places a vibration source on the ultrasound probe, separate from the ultrasound array. Compared to ARFI, the methods described herein increase the magnitude and depth of the vibration shear wave field, as well as the frequency range within the shear wave field, enabling a multi-channel and multi-directional acoustic frequency vibration source. Embodiments enable the implementation of various external vibration methods for shear wave elastography and viscoelastography. Additional embodiments enable the generation of ARFI push pulses by a vibration source, enabling the implementation of methods for ARFI elastography and its variants.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of priority to U.S. provisional patent applications (i) Ser. No. 63 / 481,513, filed January 25, 2023, and (ii) Ser. No. 63 / 488,638, filed March 6, 2023, both entitled "ULTRASOUND ON-PROBE VIBRATION SYSTEMS, METHODS AND DEVICES FOR ELASTOGRAPHIC AND VISCOELASTOPGRAPHIC MEDICAL IMAGING," the disclosures of which are incorporated herein by reference in their entireties.

[0002] (Technical field) The present invention relates to elastography and viscoelastography devices, and elastography and viscoelastography systems and methods that use ultrasound probes for ultrasound medical imaging.

[0003] Description of Related Art Elastography provides measurements and maps of tissue or object stiffness, with stiffness values ​​typically superimposed on images obtained from common imaging systems, such as, but not limited to, ultrasound, magnetic resonance imaging (MRI), computed tomography (CT), optical coherence tomography (OCT), etc. Stiffness is typically obtained by imaging the tissue or object using an imaging or sensing modality capable of monitoring the propagation of acoustic vibrations injected or induced in the tissue or object, or by measuring how the tissue or object deforms or moves in response to an applied force. Recently, elastography has been used to estimate biomechanical properties, such as stiffness, of a patient's region of interest (ROI), for example, to assess the stiffness of breast or abdominal objects as an aid in determining whether the object is benign or cancerous, or to determine other characteristics of a lesion. Some known techniques are: (a) strain or quasi-static elastography, which measures the change in shape of a region of interest and its surroundings due to compression; (b) acoustic radiation force impulse (ARFI), which involves a focused ultrasound beam momentarily compressing tissue near the focal point along the direction of the beam, and using the resulting tissue displacement and relaxation and / or propagating transverse shear waves to measure stiffness within a small region of the focal point (within about 3 mm in diameter), along with other viscoelastic parameters; and (c) ultrasound shear imaging (SSI), which involves rapid application of ARFI. These include (d) external oscillatory shear wave elastography imaging (EV-SWEI), in which an external oscillator induces shear waves in tissue over a wide ROI (up to the entire Doppler range) and the resulting shear waves are used to measure stiffness and other relevant viscoelastic parameters. MRI, CT, and OCT elastography typically employ some form of EV-SWEI, where one or more external oscillators induce shear waves in the tissue of interest, which in turn are used to measure stiffness and other relevant viscoelastic parameters.In one or more embodiments, elastography data may be obtained by vibration-controlled transient elastography (VCTE), also known as FIBROSAN® (Echosens, Paris, France), or by ultrasonic radiation force impulse (ARFI), shear imaging (SSI) elastography, or other elastography techniques. As used herein, "ARFI" shall mean acoustic radiation force impulse (ARFI) and its variants, including SSI.

[0004] Traditional ARFI techniques utilize a single transducer for both delivering radiation force and tracking the resulting tissue displacement. To obtain displacement information, a brief acoustic radiation force (0.003–1 ms) is delivered to a focal point within a region of interest (ROI), generating a localized displacement in the tissue. Immediately thereafter, for approximately 4–6 ms, Doppler ultrasound is acquired to monitor the tissue's peak displacement and recovery. By repeating this push-track procedure at multiple focal points within the ROI, a 2D stiffness (elastography) image can be created. Due to its ease of implementation, ARFI is now included as a modality in several commercially available ultrasound systems. However, while ARFI elastography is now widely available, issues have begun to emerge that limit its usefulness.

[0005] ARFI uses focused, short, high-intensity push pulses generated by the same crystals to provide imaging results in a push-track, push-track, push-track pattern. The push generates tissue displacements of up to 10 microns, but often less. The degree of displacement is related to tissue stiffness, with softer tissues displacing more than stiffer tissues. However, push pulses require stimulating the implanted ultrasound probe crystals with voltages higher than those required for standard B-mode or Doppler ultrasound imaging, which can heat the crystals to unusable levels and degrade or destroy the probe. Furthermore, the corresponding energy intensity generated at the skin surface and at the beam focus can cause tissue damage. Therefore, under regulatory safety pressure, manufacturers generally limit the use of ARFI to a depth of 8 cm, while current international elastography guidelines discourage depths beyond 6 cm due to reduced accuracy. These limitations preclude its use in tissues deeper within the body, particularly in obese patients. For usage guidelines, see, for example, G. Ferraioli, et al. (2018), “Liver Ultrasound Elastography: An Update to the World Federation for Ultrasound in Medicine and Biology Guidelines and Recommendations”, Ultrasound in Medicine & Biology, Vol. 44(12), 2018, Pp 2419-2440, ISSN 0301-5629 (doi: 10.1016 / j.ultrasmedbio.2018.07.008).As feared, ARFI has been shown to rupture pulmonary capillaries in rats due to the high pulse energy reverberating at the tissue-air interface (see DL Miller, et al. (2019), “Pulmonary Capillary Hemorrhage Induced by ARFI Shear Wave Elastography in Ventilated Rats”, J Ultrasound Med. 2019;38(10):2575-258 (doi: 10.1002 / jum.14950)).

[0006] Curvilinear probes are recommended for liver elastography, the most common type of abdominal elastography, because the imaging depth typically exceeds several centimeters. However, problems arise with ARFI when scanning depths greater than several centimeters. The focus and sharpness of the ARFI push pulse rapidly lose bandwidth with increasing depth, so the highest shear wave frequency within the shear wave cluster generated at a focus greater than several centimeters is typically below 200 Hz. This is highly limiting not only in terms of spatial resolution but also in ARFI's ability to estimate viscoelastic parameters such as dispersion. To clarify and illustrate why this is so limiting, consider the following: In the field of elastography, an object with a diameter approximately one-quarter the length of the interrogating shear wave is right on the border of the detectable range. However, noise in the data (ultrasound is noisy), feathering of the object's edges, and sudden changes in tissue impedance at the object boundary can render the object undetectable. Therefore, to interrogate such objects, it is far more desirable to have a shear wave wavelength the same size or shorter than the object. Because wavelengths shorten with increasing frequency, higher frequencies generally allow for the detection of smaller objects. As a specific example, consider a 2-mm diameter soft tissue mass with a stiffness of 10 m / s (speed of sound 1540 m / s). To detect such a mass under perfect conditions, a shear wave frequency of at least 125 Hz, or a quarter wavelength, is required. Because ultrasound is not perfect, more desirable shear waves have wavelengths of 2 mm or less, or frequencies of 500 Hz or greater. For assessment of the viscoelastic properties of a mass, such as dispersion, even higher shear wave frequencies, e.g., 1000 Hz or greater, are required to provide some confidence in the estimates. Thus, at moderate depths (a few centimeters), ARFI dispersion measurements become unreliable, and ARFI stiffness measurements rapidly lose spatial resolution, supporting and possibly illustrating the clinical guideline limit of 6 cm.

[0007] All these issues are further complicated when the ultrasound probe plane is not positioned parallel to the organ capsule surrounding the ROI. In such cases, the ARFI pulse can lose significant power, resulting in insufficient tissue forces for reliable stiffness measurements. See, for example, Figure 5.1 in the Foundation for the National Institutes of Health Biomarkers Consortium, Non-Invasive Biomarkers of Metabolic Liver Disease (NIMBLE) Project Steering Committee, “Biomarker Qualification Letter of Intent (LOI) Content Elements” (addressed to the FDA), December 10, 2020. Therefore, current elastography guidelines recommend positioning the probe plane parallel to the organ capsule (see Table 2 in G. Ferraioli et al., 2018).

[0008] In summary, the problems associated with ARFI include: (a) it is generally limited to a depth of less than 7 cm in human patients, which makes scanning deep organs and tissues such as the liver, kidneys, pancreas, and heart difficult, especially in obese patients; (b) it can destroy tissue; (c) it can destroy the ultrasound probe, which may require repair or replacement every few years; and (d) ARFI pulses that are off-axis relative to the fibrous capsules (and other high acoustic impedance boundaries) of organs make tissue stiffness measurements extremely unreliable. Summary of the Invention

[0009] In one aspect, the present disclosure provides an ultrasound elastography diagnostic apparatus including a probe assembly including an ultrasound probe configured to detect vibrations passing through subject tissue. The probe assembly includes a vibration isolation component. The probe assembly includes one or more vibration devices coupled to the ultrasound probe via the vibration isolation component. The probe assembly includes an input electrical interface communicatively connectable to a signal generator and configured to receive a vibration drive signal comprising one of (i) an acoustic radiation force impulse (ARFI) signal and (ii) an external vibration shear wave elastography imaging (EV-SWEI) signal. The input electrical interface is communicatively connected to the one or more vibration devices for generating a corresponding one of the ARFI push pulse and the EV-SWEI vibration. The probe assembly includes an output electrical interface communicatively connected to the ultrasound probe for receiving a tracked vibration waveform. The output electrical interface is communicatively connectable to an image processor for generating a map of one or more viscoelastic properties included in the tracked vibration waveform.

[0010] In another aspect, the present disclosure provides a method for manufacturing an ultrasound elastography diagnostic apparatus. In one or more embodiments, the method includes attaching one or more vibration devices to a vibration isolation component. The method includes forming a probe assembly by attaching the vibration isolation component to an ultrasound probe configured to detect vibrations passing through subject tissue. The method includes communicatively coupling an input electrical interface to one or more vibration devices configured to generate at least one of: (i) acoustic radiation force impulse (ARFI) push pulses; (ii) external vibration shear wave elastography imaging (EV-SWEI) vibrations. The method includes communicatively coupling an output electrical interface to the ultrasound probe.

[0011] In an additional aspect, the present disclosure provides a method for performing an ultrasound elastography diagnostic procedure. In one or more embodiments, the method includes positioning a probe assembly in contact with subject tissue. The probe assembly includes: (i) an ultrasound probe configured to detect vibrations passing through the subject tissue; (ii) a vibration isolation component; and (iii) one or more vibration devices coupled to the ultrasound probe via the vibration isolation component, the one or more vibration devices configured to generate at least one of (a) acoustic radiation force impulse (ARFI) push pulses and (b) external vibration shear wave elastography imaging (EV-SWEI) vibrations. The method includes transmitting one of an ARFI signal and an EV-SWEI signal to the one or more vibration devices to generate a corresponding one of the ARFI push pulses and the EV-SWEI vibrations. The method includes detecting, at the ultrasound probe, a tracked vibration waveform resulting from the corresponding one of the ARFI push pulses or the EV-SWEI vibrations. The method includes mapping, at an image processor, one or more viscoelastic properties derived from the tracked vibration waveform.

[0012] These and other features are described in more detail in the illustrative embodiments below. In general, it should be understood that features of one embodiment may be used in combination with features of another embodiment, and that the embodiments are not intended to limit the scope of the invention.

[0013] The description of the exemplary embodiments may be read in conjunction with the accompanying drawings. It will be understood that for simplicity and clarity of illustration, elements shown in the drawings have not necessarily been drawn to scale. For example, the dimensions of some of the elements are exaggerated relative to other elements. Embodiments incorporating the teachings of the present disclosure are shown and described in connection with the drawings presented herein. [Brief explanation of the drawings]

[0014] [Figure 1]FIG. 1 is a diagram of a dual piezoelectric transducer bar mounted on a standard ultrasound probe, providing a vibration field over a full range of acoustic frequency bands, either mono or stereo. [Figure 2] FIG. 1 is a diagram of a segmented piezoelectric transducer bar mounted on a standard ultrasound probe, providing a multi-channel full-range acoustic frequency band vibration field or ultrasonic frequency ARFI push pulse. [Figure 3] FIG. 1 is a front (patient contact) view showing the position of the piezoelectric transducer bars in relation to the ultrasound probe array. [Figure 4] 1A-1C are diagrams of the front (patient contact) surfaces of three common ultrasound types showing the location of the piezoelectric transducer bars in relation to the ultrasound probe array. [Figure 5] FIG. 10 is a diagram of acoustic vibration patterns using the EV-SWEI method with dual piezoelectric bars. [Figure 6] FIG. 1 is a diagram (end view) of a piezoelectric transducer bar assembly permanently installed within an ultrasound probe housing. [Figure 7] FIG. 1 is a diagram of a piezoelectric transducer bar permanently installed within an ultrasound probe housing (front view). [Figure 8] FIG. 1 is a flow diagram of an electronic system used to signal devices. [Figure 9] FIG. 1 is a diagram of two tissue-contacting piezoelectric tactile driver rings or half rings embedded in an intracavity ultrasound probe. [Figure 10] FIG. 1 is a diagram of a tissue-contacting piezoelectric tactile driver embedded in an intracavity ultrasound probe. [Figure 11] FIG. 1 is a diagram of the tip of a multi-source / multi-channel piezoelectric tactile driver button or rod surrounding an ultrasonic linear probe. [Figure 12] FIG. 1 is a block diagram of an ultrasound elastography diagnostic apparatus including a probe assembly including an ultrasound probe and a vibration device communicatively coupled to a signal generator and an image processor. [Figure 13]FIG. 1 is a flow diagram of a method for manufacturing an ultrasound elastography diagnostic device. [Figure 14] FIG. 1 is a flow diagram of a method for performing an ultrasound elastography diagnostic procedure. DETAILED DESCRIPTION OF THE INVENTION

[0015] The systems and methods described herein overcome the problems of ARFI by enabling (a) the construction of more durable probes for ARFI elastography, (b) the expansion of the ARFI push pulse source over a larger surface area, allowing for deeper penetration while reducing the risk of damage to superficial tissue, and (c) the utilization of the EV-SWEI method without the need for additional external transducers (although, if desired, additional external transducers can be used to enable very deep shear wave penetration into tissue). The ability to utilize a single probe without additional external exciters and without overdriving tracking elements provides an attractive and convenient package for performing either ARFI or EV-SWEI. Furthermore, switching to EV-SWEI eliminates safety concerns associated with ARFI's push pulse ultrasound intensity, both at the surface and at the focal point, and also removes the depth limitations associated with ARFI. An additional advantage of utilizing EV-SWEI as described herein is the ability to generate shear wave frequencies in excess of 5,000 Hz, a much broader range than ARFI. This wider range not only improves image resolution due to the shorter wavelengths associated with higher frequencies, but also improves the reliability of viscoelastic measurements. Collectively, the improvements provided by the systems and methods described herein allow for better characterization of tissue mechanical properties, thereby better detecting the smallest cancer masses and other abnormalities.

[0016] The method described herein separates the push and track functions of ARFI into two separate devices separated by shock-absorbing material, with the push function placed in a separate device that surrounds the ultrasound probe. This system allows for greater control of vibration, including greater acoustic range and tissue penetration depth, and avoids heating of the ultrasound probe. It also allows for continuous vibration, similar to EV-SWEI, which provides the multiple benefits described above. Furthermore, the ultrasound probe does not need to switch back and forth between push and track, allowing for more complete and thorough real-time imaging and gating of moving tissue, such as the heart.

[0017] In one aspect, the present disclosure provides systems, methods, and apparatus (hereinafter "systems") that include monitoring signals from a set of sensors installed on a user.

[0018] Systems, methods, and devices are disclosed that are designed to simultaneously deliver continuous, high-fidelity, full-range (5-8,000 Hz) multi-frequency vibrations within the human body while maintaining waveform consistency with externally induced waveforms. Frequencies in the upper range are required to achieve fine specificity for tissue targets, e.g., 1,000-6,000 Hz for the cornea, 40-1,200 Hz for the liver, and 40-3,000 Hz for the breast. The full frequency range allows users to obtain maximum specificity by eliminating limitations imposed by inferior vibration systems, thereby allowing them to select the highest upper frequency limit based on the round-trip travel time required for ultrasound tracking of tissue displacement, the size of the smallest object to be detected, and the maximum stiffness expected within the tissue.

[0019] Thus, in one aspect, the present disclosure provides systems, methods, and devices for external vibration elastography and viscoelastography (EV-SWEI). In another aspect, the present disclosure provides systems, methods, and devices for acoustic radiation force impulse (ARFI) ultrasound elastography and viscoelastography.

[0020] The system of the present invention can offer the following advantages over known ARFI systems: (a) reduced risk of damage to the ultrasound transducer elements (piezoelectric material for transmitting and receiving ultrasound waves); (b) reduced risk of damage to the patient's tissue; (c) a wide frequency range of 5000 Hz and above, which leads to better resolution for small objects and better viscosity measurements; and (d) the availability of multiple wave sources, which can generate crawling waves, echo waves, etc., providing extended imaging depth and allowing multiple independent signals generated simultaneously to provide stiffness and viscosity assessments, meaning the system can better detect smaller objects while also improving tissue characterization to help distinguish healthy tissue from carcinomas, benign tumors, etc.

[0021] Existing ultrasound imaging has difficulty detecting cancers and other abnormalities in deep tissues during their smallest and earliest stages of development. The disclosed method provides a solution for detecting small cancer masses and other abnormalities deep within the human body without the need for often invasive elastography procedures. The method is non-destructive to hardware or tissue and non-invasive to the subject (patient).

[0022] The present invention provides an acoustic radiation force impulse (ARFI) ultrasound diagnostic device, in which two ARFI functions are split into two separate hardware systems, but both are housed within the same device (probe). The present invention also provides a method of using the acoustic radiation force impulse (ARFI) system, in which two ARFI functions are split into two separate hardware systems, but both are housed within the same device (probe). Typically, the subject is a human being seeking evaluation, as a clinician desires to use the present invention as part of a diagnosis. Also, a system or set with two or more probes can be used, whereby, in one embodiment, the present method can include an ultrasound system for simultaneously processing a first signal from a first ultrasound probe and a second signal from a second ultrasound probe. The probes can be adapted for a particular anatomical region or indication. For example, the anatomical region can be selected from the group consisting of the forehead region, the anterior tibial region, the foot region, the distal radius region, the elbow region, the presternal region, the temporal bone region, and regions requiring an intracavity probe, such as the vagina, rectum, esophagus, etc.

[0023] According to some embodiments, a system for estimating and displaying an internal region of a subject, in which a dual piezoelectric transducer bar is attached to a standard ultrasound probe, comprises a multi-directionally propagating shear wave source configured to provide a vibration field in a mono or stereo full range acoustic frequency band and to simultaneously induce shear waves at different vibration frequencies within a region of interest (ROI) of the subject, an imaging system that measures the displacement as a function of time of each voxel within the ROI in the presence of the induced shear waves, and a computer processor configured to apply a computer algorithm to the displacements and calculate respective shear wave velocities within the ROI taking into account the vibration frequencies, and further calculate respective internal representations.

[0024] According to some embodiments, the processor for the dual piezoelectric acoustic frequency transducer system can be further configured to consider in the computer algorithm the effect of attenuation (alpha) as the shear waves propagate; the shear wave source can comprise a surface having multiple vibration frequency sources embedded in an active area of ​​the surface, the multiple vibration frequency sources configured to vibrate simultaneously; the imaging system can comprise an ultrasound scanner and an imaging ultrasound transducer, the scanner and transducer can be configured to measure displacement to a depth of at least 10 cm within the patient and to measure displacement within the patient's liver or breast; the imaging system can be an MRI scanner or an OCT (optical coherence tomography) scanner rather than an ultrasound scanner; the vibration frequencies can include at least frequencies up to 5000 Hz and can include frequencies in the range of 40 to 7000 Hz; and the source can be configured to step the vibration frequency in selected steps within a selected frequency range.

[0025] According to some embodiments, the dual piezoelectric acoustic frequency transducer is fabricated from one of a piezoelectric ceramic material, a piezoelectric ceramic composite material, a piezoelectric ceramic single crystal material, a capacitive microelectromechanical ultrasonic transducer chip, a piezoelectric ceramic microelectromechanical ultrasonic transducer chip, or a polymer piezoelectric material. According to some embodiments, the dual piezoelectric acoustic frequency transducer is an array fabricated from one of a piezoelectric ceramic material, a piezoelectric ceramic composite material, a piezoelectric ceramic single crystal material, a capacitive microelectromechanical ultrasonic transducer chip, a piezoelectric ceramic microelectromechanical ultrasonic transducer chip, or a polymer piezoelectric material. In one case, the central element array and the lateral element array are capacitive microelectromechanical ultrasonic transducers (CMUTs). In another case, the central element array and the lateral element array are piezoelectric ceramic microelectromechanical ultrasonic transducers (PMUTs).

[0026] The present invention relates to diagnostic medical imaging, and more specifically to elastography. In its most direct sense, the present invention relates to magnetic resonance elastography and optical coherence elastography, in addition to ultrasound elastography. Some soft tissue diseases (including, but not limited to, some cancers) cause diseased areas to have viscoelastic properties that differ from those of surrounding non-diseased tissue. For example, breast tumors may be stiffer than surrounding healthy breast tissue. As used herein, "elastography" refers to both elastography and viscoelastography. Technically, viscoelastography includes both stiffness and dispersion (and / or viscosity), whereas elastography includes stiffness only. This disclosure recognizes that common usage in the field has changed, whereby "elastography" typically includes both stiffness and dispersion (and / or viscosity), but is still sometimes used to refer to stiffness only. This disclosure may be applied to improve commercially available machines with elastography that similarly estimate dispersion (and / or viscosity).

[0027] Ultrasound elastography can be used in vivo to locate diseased areas within organs. In ultrasound elastography studies, a shear-inducing transducer, acting as a vibration source, introduces acoustic energy into the organ of interest, generating shear waves within the organ and distorting the organ tissue. By locating areas of strain change and measuring the strain in those areas, various material properties, such as stiffness, elasticity, viscosity, attenuation, wave speed, phase angle, and frequency dispersion, can be determined, thereby determining the location and severity of disease.

[0028] One type of ultrasound elastography utilizes echo fields (also known as reverberant shear wave fields). This technique uses one or more shear-inducing transducers to generate multiple shear waves along multiple directions. This diversity of differently oriented shear waves is also enhanced by all reflections that naturally arise from organ boundaries and from inhomogeneities within the organ.

[0029] It is possible to estimate shear wave velocity (SWS), soft-tissue stiffness, and soft-tissue dispersion, which is the variation of SWS with frequency and is related to tissue loss and attenuation. However, until now, such estimation required the use of autocorrelation with a wide autocorrelation window. This can limit the spatial resolution of shear wave velocity maps that indicate the location of suspect structures in the organ under examination. There are also situations in which the shear wave field may not be uniformly reflected. Such situations can arise, for example, near a strong vibration source that generates vibrations only in one direction, or when sliding surfaces surrounding a particular organ, such as the heart, allow vibrations to enter the organ only through certain connective tissues, or when anatomical structures, such as the pelvis, create regions that naturally focus and enhance certain wavelengths from certain directions while blocking others.

[0030] The family of invasive ultrasound imaging probes includes probes of various shapes and designs adapted to the internal morphology of the organ being imaged. A distinction can be made between: (i) intracavity probes used for intravaginal and intrarectal diagnostics; (ii) endoscopic probes, which are extensions of invasive instruments, in which the imaging transducer is attached to the tip of the endoscope's (flexible or rigid) tube, and the endoscope's handle usually houses the instrument's controls; (iii) catheter-based probes, in which the ultrasound transducer is attached to the tip or distal end of the corresponding catheter tube; and (iv) specialized imaging devices designed for specific applications, such as brain imaging (e.g., "burrhole" probes) or surgical monitoring (e.g., "per-op" probes). Generally speaking, catheter-based instruments for ultrasound diagnostics are very similar to endoscopic tubes but have much smaller tube diameters, and burrhole-type probes can be considered customized versions of intracavity probe devices. Per-op probes are specialized instruments, each specifically designed for a specific surgical application. As a result, there is a wide variety of such devices, with compact housings being their common feature.

[0031] The foregoing summary encompasses simplifications, generalizations, and omissions of detail, and is not intended to be a comprehensive description of the claimed subject matter, but rather to provide a brief overview of some of its related functionality. Other systems, methods, functionality, features, and advantages of the claimed subject matter will become apparent to one skilled in the art upon examination of the following figures and detailed description.

[0032] Definition: The embodiments described below in the context of a user input device are analogously valid for the respective method, and vice versa. Furthermore, it will be understood that the embodiments described below may be combined, e.g., parts of one embodiment may be combined with parts of another embodiment.

[0033] It should be understood that the terms "on," "over," "top," "bottom," "down," "side," "back," "left," "right," "front," "lateral," "side," "up," and "down," when used in the following description, are used for convenience and to aid in the understanding of relative location or orientation, and are not intended to limit the orientation of a device, or structure, or portion of a device or structure. Additionally, the singular words "a," "an," and "the" include the plural unless the context clearly dictates otherwise. Similarly, the word "or" is intended to include "and" unless the context clearly dictates otherwise.

[0034] Acoustic communication refers to the passage of sound waves between two points in a predetermined manner. Typically, this is achieved by selecting a desired path between the two points that allows the sound waves to pass directly or indirectly. In the case of ultrasound, direct passage of ultrasound occurs, for example, when an ultrasound crystal is disposed directly (usually in contact with) an acoustic coupling material, such as a composite material. Indirect passage of ultrasound occurs, for example, when an ultrasound crystal is located a predetermined distance from the acoustic coupling material, or when multiple acoustic coupling materials (often dissimilar materials) form two or more layers.

[0035] An ultrasound acoustic coupler refers to a connection or connections between an ultrasound crystal and a material that reflects or passes ultrasound pulses and is not part of the device. The acoustic coupler allows ultrasound waves to pass through. It is desirable for such a coupler to minimize attenuation of the ultrasound pulse or signal and minimize changes in the physical properties of the ultrasound waves, such as wave amplitude, frequency, shape, and wavelength.

[0036] Crystal refers to the material used to transmit ultrasound waves in an ultrasound transducer, and includes all current and future materials used for this purpose. Crystals are typically made of lead zirconate titanate, lead barium titanate, lead metaniobate, lithium sulfate, polyvinylidene fluoride, or combinations thereof. While the crystal is typically a piezoelectric material, any material that contracts and expands upon the application of an external voltage can be used, provided such material is capable of generating ultrasound waves as described herein and known in the art. Crystals emit ultrasound waves because the rapid mechanical contraction and expansion of the material displaces the medium, generating the ultrasound waves.

[0037] A detector refers to a structure capable of measuring currently known or future developed ultrasonic waves or pulses. To measure ultrasonic waves, a crystal containing a dipole is typically used. The crystal, such as a piezoelectric crystal, shifts the orientation of the dipole in response to an applied current. When the applied current fluctuates, the crystal vibrates, generating ultrasonic waves in the medium. Conversely, the crystal vibrates in response to ultrasonic waves, which mechanically deforms the crystal, thereby changing the alignment of the dipoles within the crystal. This, in turn, changes the charge distribution and generates a current across the crystal's surface. Electrodes connected to an electronic circuit sense the potential difference across the crystal related to the incident mechanical pressure.

[0038] The terms "individual," "patient," or "subject" are used interchangeably. None of these terms require or are limited to a condition characterized by supervision (e.g., constant or intermittent) by a medical professional (e.g., a physician, registered nurse, nurse practitioner, physician assistant, attendant, hospice worker). The terms "individual," "patient," or "subject" encompass mammals. Examples of mammals include, but are not limited to, all species of the mammalian class: humans; non-human primates such as chimpanzees and other apes and monkeys; farm animals such as cows, horses, sheep, goats, and pigs; pets such as rabbits, dogs, and cats; and laboratory animals, including rodents such as rats, mice, and guinea pigs. In some embodiments, the mammal is a human.

[0039] A linear array refers to a transducer design in which piezoelectric elements are arranged in a line along one or more axes. Elements can be fired in sequential, non-sequential, and simultaneous firing patterns, or a combination thereof. Sequential firing allows for the formation of various beams based on the order, intensity, and delay between elements. The number of elements in an array typically determines the precision with which the beam can be steered. Segmented firing allows for simultaneous activation of groups or segments of elements, resulting in a deeper near field and a less divergent far field compared to sequential activation. However, segmented linear arrays generate coarser beams compared to sequential linear arrays with the same number of elements. As used herein, the term "piezoelectric element" refers (as the context dictates) to the piezoelectric elements in standard ultrasound probes for clinical diagnostic imaging. As used herein, the terms "piezoelectric bar," "piezoelectric transducer," and "piezoelectric button" refer to additional "snap-on" or "built-in" piezoelectric elements that provide the distinct functions of generating ARFI push pulses and EV-SWEI vibrations, although these may also be referred to as "piezoelectric elements" when the context dictates.

[0040] The transmit angle refers to the angle at which the ultrasound beam intersects with an object or tissue plane. The transmit angle is typically measured relative to the object or tissue plane. The object or tissue plane has a reference angle of 0 degrees.

[0041] The transmit frequency refers to the frequency of the waves transmitted from the acoustic source. The transmit frequency of medical ultrasound ARFI is typically in the 1-8 MHz range. Higher frequencies provide better spatial resolution, but tissue penetration decreases with increasing frequency, especially in dense adipose tissue. Lower transmit frequencies generally result in lower spatial resolution but better tissue penetration. The transmit frequency of EV-SWEI is typically in the 40-5,000 Hz range and has a much longer wavelength than ultrasound, allowing for deeper penetration. While less directional, partial steering is still possible, especially when converted to short-wavelength shear waves. Furthermore, at these low frequencies, it is easy to combine multiple frequencies to form and transmit complex waveforms. The transmit frequencies of EV-SWEI in this disclosure are generally referred to as "acoustic frequencies" because the acoustic frequency range roughly coincides with the frequency range of EV-SWEI.

[0042] An ultrasonic pulse refers to an ultrasonic wave transmitted by an ultrasonic source. Typically, the pulse has a predetermined amplitude, frequency, and waveform. The ultrasonic pulse can be composed of a sine wave with a single frequency or a variable frequency, and a single amplitude or a variable amplitude. In addition to sine waves, square waves or other waveform patterns may be employed. A square wave can be obtained by adding a single-frequency sine wave to another sine wave. Adding waves can then result in a square wave pattern. Similarly, acoustic frequency waves can be combined to produce similar results for short pulses as for continuous waveforms.

[0043] Ultrasound signals refer to ultrasound waves that are reflected from an object or tissue interface and then measured by an ultrasound detector. Clinical ultrasound signals are typically in the frequency range of 1 to 35 MHz.

[0044] An ultrasound source refers to a structure capable of generating ultrasonic waves or pulses, whether currently known or developed in the future. Crystals, such as piezoelectric crystals, that vibrate in response to the application of electric current can be used as ultrasound sources. The source can be made from one of the following: piezoelectric ceramic material, piezoelectric ceramic composite material, piezoelectric ceramic single crystal material, capacitive microelectromechanical ultrasonic transducer chip, or piezoelectric ceramic microelectromechanical ultrasonic transducer chip. PZT (lead zirconate titanate) is often used as the transmitting piezoelectric element material, but lead-free materials can be used as well. These materials include quartz crystal, lithium niobate (LiNbO), potassium niobate tantalate (K(Ta,Nb)O), barium titanate (BaTiO), lithium tantalate (LiTaO), and strontium titanate (SrTiO). Similarly, an acoustic frequency source refers to a structure capable of generating acoustic frequency waves or pulses, whether currently known or developed in the future. Materials used to make acoustic frequency sources have been disclosed above. In some embodiments, the acoustic frequency source is a piezoelectric acoustic frequency transducer (or piezoelectric tactile transducer) made from piezoelectric materials used in acoustic speakers for high frequency or "tweeter" drivers. In some embodiments, the source is a piezoelectric ceramic acoustic frequency transducer (or piezoelectric ceramic tactile transducer). In still other embodiments, the acoustic frequency source is the same as an ultrasound source and can therefore be configured to emit either ARFI frequency push pulses or acoustic frequency vibrations.

[0045] As used herein, the terms "ultrasound transducer" and "ultrasound probe" are used interchangeably.

[0046] Ultrasound refers to either an ultrasonic signal or a pulse.

[0047] In one or more embodiments, the innovation provides an acoustic radiation force impulse (ARFI) ultrasound diagnostic device, where two ARFI functions are split into two separate hardware systems, but both are housed within the same device (probe). The innovation also provides a method of using an acoustic radiation force impulse (ARFI) system, where two ARFI functions are split into two separate hardware systems, but both are housed within the same device (probe). In one or more embodiments, the two functions are split into two separate hardware systems, but are not combined into the same probe (e.g., a snap-on boot that encircles the ultrasound probe).

[0048] Acoustic frequency tactile vibrations are generated by sound waves transmitted by physical vibrations through objects rather than through air. Elastography is a medical imaging method that applies acoustic frequency tactile vibrations to the human body and then uses standard imaging methods, such as, but not limited to, ultrasound, to determine tissue stiffness and viscosity using measurements of how the tissue responds to various vibration waveforms and acoustic frequencies. For example, cancerous lesions are generally stiffer than surrounding healthy tissue, and the system can detect and map the size, shape, and characteristics of cancer. The method is also used to determine scar tissue, fat, steatosis, cirrhosis, inflammation, and many other abnormalities.

[0049] Acoustic radiation force impulse (ARFI) is a common type of elastography in which tactile vibratory forces are generated by an ultrasound array and do not use an external vibration source or originate from a source other than the array itself. This method carries inherent risks to both patient safety and ultrasound probe durability.

[0050] ARFI involves injecting a short power surge into the ultrasound array crystals, causing them to react to the surge and temporarily increase their physical size. This produces a short burst of tactile vibrations, which are then focused on an area, typically within 6.5 cm of the ultrasound contact point. The ultrasound probe then instantly switches to receive mode, mapping the vibration effects in the form of shear waves generated by the energy burst in the tissue and providing a stiffness reading. However, the sudden energy burst at the focal point can damage the tissue. Energy bursts within the probe array can also damage the ultrasound crystals. Probes used for ARFI elastography are typically used for only a few years and must then be replaced or repaired.

[0051] In one or more embodiments, the intracavity ultrasound probe may be a linear probe, a sector probe, a convex probe, or an intracavity probe of other configurations. In one or more embodiments, the ultrasound probe may have one or more piezoelectric transducers (transducers) for transmitting ultrasound waves and one or more piezoelectric transducers (transducers) for receiving ultrasound waves.

[0052] The present invention can be introduced into the human anatomy, for example, through natural openings or by percutaneous or surgical access to lumens, vessels, or body cavities. While the present systems and methods are described in connection with percutaneous cardiac interventions on the human body, it should be understood that percutaneous or surgical intervention and access may be for percutaneous interventions on any biological entity, such as an animal, or for non-biological objects through small openings in probe devices (e.g., electronic devices, inanimate objects, etc.) or structures (e.g., buildings, caves, etc.). Furthermore, the present systems are applicable to other forms of Doppler tomography. Furthermore, while embodiments are described in connection with intracavity probes, the present systems, devices, and methods are equally applicable to endoscopic devices for imaging inserted through any opening, such as transnasal, transvaginal, transrectal, transesophageal echocardiography (TEE) probes, intracavity probes, etc.

[0053] One embodiment of an imaging endoscopic device is a transesophageal echocardiogram (TEE) probe for insertion into the esophagus, and the present devices, systems, and methods are described using such a TEE probe. However, it should be understood that other types of probes may be used for other desired surgical and imaging applications, such as insertion into body orifices such as the throat, nose, or rectum. As used herein, "endocavitary probe" includes transrectal, transvaginal, and other intracavitary probes, such as transesophageal (TEE) probes. Intracavitary probes can be used for scanning and imaging the prostate, pelvic floor, and urethra. As used herein, "endocavitary ultrasound" includes endorectal ultrasound (ERUS) and transrectal ultrasound (TRUS) embodiments.

[0054] Additionally, the endoscopic devices for imaging of the present invention, according to the present devices, systems, and methods, may be used alone or in conjunction with surgical instruments to perform a desired procedure, such as the removal or destruction of unwanted growths or tissue. The endoscopic devices of the present invention may be used for non-invasive or minimally invasive procedures for therapeutic and imaging purposes, and may be automatic and / or manual, self-guided using, for example, a joystick, or guided using conventional guidance devices.

[0055] Typically, ARFI only produces a frequency range below 200 Hz unless it is used close to the surface (less than 3 cm). However, an extended frequency range is needed to determine the smallest target objects and to determine the dispersion (viscosity) of the target objects.

[0056] The method proposed herein does not cause damage to the ultrasound hardware. Furthermore, because the vibration effect is extended over a much wider range, damage to human tissue is minimized. In one or more embodiments, the frequency range is limited to the range possible with piezoelectric acoustic frequency transducer materials, currently 5-20,000 Hz. Furthermore, because there is no need to switch the ultrasound probe from push to track, the ultrasound probe can maintain its normal contact function while the vibration source continues to function continuously, resulting in a significant system improvement.

[0057] In one or more embodiments, the system includes a power source configured to apply appropriate power to the transducer to image tissue within a patient. For example, the power input to the transducer can be 150 W, 200 W, 500 W, 750 W, or 1000 W to achieve an output suitable for deep imaging of the patient.

[0058] The ultrasonic transducer may be, for example, any one of a magnetostrictive ultrasonic transducer that uses the magnetostrictive effect of a magnetic material, a piezoelectric ultrasonic transducer that uses the piezoelectric effect of a piezoelectric material, and a capacitive micromachined ultrasonic transducer (cMUT) that transmits and receives ultrasonic waves using the vibration of hundreds or thousands of micromachined thin films. In addition, other types of transducers that generate ultrasonic waves by electrical signals or generate electrical signals by ultrasonic waves may also be used as ultrasonic transducers.

[0059] For example, the ultrasonic transducer element may include a piezoelectric vibrator or a thin film. When an AC current is applied from a power source to the piezoelectric vibrator or thin film of the ultrasonic transducer, the piezoelectric vibrator or thin film vibrates at a predetermined frequency in response to the applied AC current, generating ultrasonic waves of the predetermined frequency in response to the vibration frequency. Meanwhile, when an ultrasonic echo wave of the predetermined frequency reaches the piezoelectric vibrator or thin film, the piezoelectric vibrator or thin film vibrates in response to the ultrasonic echo wave. At this point, the piezoelectric vibrator or thin film outputs an AC current of a frequency corresponding to the vibration frequency.

[0060] In one or more embodiments, the method proposed herein takes the two functions of ultrasound probes currently found in ARFI and separates them into two separate hardware systems while being housed within the same device (the probe). In one or more embodiments, the method enables the benefits of ARFI without damaging the hardware or tissue, and allows for the added benefits of a much wider frequency range, a much wider shear wave vibration field, and continuous operation of both the probe and the vibration source.

[0061] In one or more embodiments, the ultrasound system of the present invention uses Acoustic Radiation Force Impulse (ARFI). In one or more embodiments, the ultrasound system uses other ultrasound modalities, such as External Vibration Shear Wave Elastography Imaging (EV-SWEI), Color Flow, B-mode, A-mode, M-mode, Spectral Doppler, Acoustic Streaming, Tissue Doppler Module, and C-scan.

[0062] In one or more embodiments, the method proposed herein separates the ARFI pulse push function from the ultrasound probe and places it in a bar made of piezoelectric material similar to the crystals used in ultrasound arrays. This type of piezoelectric material is commonly used in audio speakers, particularly as high-frequency or "tweeter" drivers. In one or more embodiments, the bar is sealed in a glass or polycarbonate sleeve that isolates the piezoelectric material from tissue and is then mounted in a rubber insulating material that limits vibration "feedback" into the ultrasound probe. In one or more embodiments, the vibrating assembly can be mounted in a removable snap-on rubber boot molded to fit many specific probe designs. Also, in one or more embodiments, the vibrating assembly can be integrated directly into the probe and manufactured by a commercial ultrasound hardware manufacturer.

[0063] In one or more embodiments, only two piezoelectric sources are provided for two channels (stereo). In other embodiments, segmented piezoelectric sources enable multi-channel (surround). In still other embodiments, the number of piezoelectric sources on each side of the ultrasound transducer matches the number of ultrasound elements, and in still other embodiments, the number may exceed the number of ultrasound elements. For embodiments directed to EV-SWEI techniques, at least two independent sources are positioned on either side of the ultrasound array, enabling unique elastography modalities such as crawling waves, reverberation, and many types of partial phase inversion, delay, and other techniques known to those skilled in the art. Each modality may provide unique results that exceed the capabilities of current ARFI systems. Thus, the present system improves on all aspects of imaging modalities for elastography and viscoelastography.

[0064] In one or more embodiments, the piezoelectric vibration assembly is driven by an amplifier that is matched to the impedance characteristics of the piezoelectric bar material. An acoustic frequency waveform, specially designed for tissue type, body size, BMI, etc., is generated by software within the ultrasound machine and sent to the amplifier. In one or more embodiments, the imaging system turns on the vibrations, then takes a scan using the ultrasound elements in the probe, and then immediately turns both off.

[0065] Referring to the drawings, Figure 1 illustrates an example of a first probe assembly 100a including an ultrasonic probe 101a having an ultrasonic device 102a along its distal edge 104. In one or more embodiments, a boot 106a, such as molded rubber, is attached around the distal end 104 of the ultrasonic device 102a by snap-on, friction, strap, or other methods (collectively "snap-on") to position dual vibration devices 108a (e.g., double-glass encapsulated piezoelectric bar material for a two-channel attachment configured to accommodate a full range of acoustic frequencies) along opposing elongated sides of the ultrasonic device 102a. Figure 1 illustrates the first probe assembly 100a, where the wearable attachment of the piezoelectric bar material (vibration devices 108a) enables elastography and viscoelastography ultrasound measurements of subject tissue. The dual piezoelectric bars allow for the injection of mono or stereo vibration fields into tissue, generating numerous tactile acoustic wave fields, including but not limited to compressional / longitudinal wave fields and various shear wave fields (crawling, reverberant, unidirectional, etc.). This method provides a simple and efficient method for the non-invasive delivery of EV-SWEI tactile acoustic vibrations into tissue. Not shown here is a damping material for acoustically isolating the vibrations of the dual piezoelectric bars from the ultrasonic device 102a, thereby minimizing the impact of the vibrations on ultrasonic tracking of tissue motion.

[0066] FIG. 2 illustrates an example of a second probe assembly 100b including an ultrasonic probe 101b having an ultrasonic array device 102b along its distal edge 104. As shown in FIG. 1, a molded rubber boot 106b is attached around the distal edge 104 of the ultrasonic array device 102b, and dual vibrating array devices 107b (in this embodiment, glass-encased, dual-segment piezoelectric bar material configured as a two-channel attachment for full-range acoustics) are positioned along opposite elongated sides of the ultrasonic device 102b. Each vibrating array device 107b includes multiple vibrating piezoelectric bars 108b. The second probe assembly 100b provides a snap-on attachment 106b that enables ultrasonic vibrations for elastography and viscoelastography, with multiple short strips of piezoelectric bar material ("segments") positioned parallel to the ultrasonic probe and, in some embodiments, perpendicular to the probe at both ends (not shown), and damping material (not shown) acoustically isolates the vibrations of the dual-segment piezoelectric bars 108b from the ultrasonic device 102b. This method allows for the injection of stereo or multi-channel vibration fields into tissue, generating numerous tactile acoustic waveforms, including, but not limited to, compressional / longitudinal waves and shear waves (e.g., crawling, reverberation, etc.). This method offers additional benefits, such as beam steering, phase alignment, and Ambisonics, for implementing the EV-SWEI method. In embodiments where the piezoelectric material and electronics are selected to enable ultrasound transmit frequencies and the number of segments in each bar is approximately equal to the number of ultrasound array elements, ARFI push pulses can then be further generated. Note that in embodiments capable of both EV-SWEI and ARFI, the ultrasound probe can function fully within the normal Doppler tracking method and does not need to be switched to generate ARFI focused push pulses.

[0067] As used herein, the term "damping material" or "damper material" means vibration-damping elastic polymer or elastomeric materials (e.g., viscoelastic urethane polymer materials such as Sorbothane® materials by Sorbothane, Inc., Kent, Ohio), thermoplastic elastomer materials (TPEs), thermoplastic polyurethane materials (TPUs), and / or other suitable types of materials for absorbing shock, isolating vibrations, and / or attenuating noise. In one or more embodiments, the damping material comprises one or more polymers selected from the group consisting of polydimethylsiloxane (PDMS), polyvinyl chloride (PVC), ethylene propylene rubber (EPR), styrene butadiene rubber (SBR), nitrile butadiene rubber (NBR), thermoplastic polyurethane (TPU), polyisoprene (IR), PTFE (Teflon), polyethylene, nylon, polyetheretherketone (PEEK), nylon, acrylic (PMMA), polycarbonate (Lexan), polyimide, latex, polyvinyl chloride (PVC), silicone rubber, polyurethane, and polyester. In one embodiment, the damping material is an elastomer, such as polyurethane or silicone.

[0068] Figure 3 is a front view of the distal end of a first probe assembly 100a, which has a planar rectangular array of dual vibration devices 108a on either side of an ultrasonic device 102a. A second probe assembly 100b (Figure 2) has a similar or identical planar rectangular array. Embodiments of the present disclosure may be arranged in other arrays. Figure 4 shows a three-dimensional view of the distal ends of three probe assemblies 100c, 100d, and 100e, which are not planar rectangular but instead have linear, curved, and phased array distal ends 104c, 104d, and 104e for each ultrasonic probe type.

[0069] FIG. 5 illustrates how two tactile acoustic vibration devices can generate complex overlapping vibration fields (represented by circles) using the method described in FIG. 1. As shown, the ultrasonic device 102a of the ultrasonic probe 101a is surrounded on both sides by a molded boot 106a that supports dual vibrating sections 108a of piezoelectric material within a piezoelectric casing. Monophonic or stereophonic vibrations are emitted from piezoelectric tactile acoustic strips attached to both sides of the ultrasonic probe and array, generating several types of waveforms, with shear waves being primarily useful for elastography and viscoelastography. The ultrasonic device 102a performs its tracking function in a standard manner, e.g., by insonifying tissue within the transmit angle with ultrasonic transmissions (typically Doppler chirps) represented by trapezoids, recording the received echoes, and then communicating this data to the ultrasound machine for processing and reconstruction.

[0070] 6 is a cross-sectional side view of a vibration device 108a comprising a piezoelectric bar 112 encased in a glass or hard plastic piezoelectric casing 114 and surrounded by a damping material 116 for acoustic isolation from the ultrasonic device 102a. Optionally, the piezoelectric bar 112 encased in the piezoelectric casing 114 may include a spacing material or other non-isolating material between the piezoelectric casing 114 and the damping material 116 (not shown).

[0071] FIG. 7 is a diagram of a probe assembly 100f formed with a dual vibration device 108f comprised of piezoelectric bar material and damping material, embedded directly into the ultrasonic probe face 118 that further supports the ultrasonic array device 102f, rather than a snap-on attachment. This method provides an isolated piezoelectric solution that is manufactured as part of the ultrasonic probe 101f. This method includes all of the components described for the snap-on embodiment, but they are manufactured as part of a commercially available probe. The ultrasonic probe face 118 includes or comprises damping material around the piezoelectric material to prevent vibrations from the piezoelectric material from being detected by the ultrasonic array device 102f.

[0072] 8 is a communications flow chart of the electronic system 800 required for the method. An ultrasound machine 801 sends waveforms from various scan programs to a mono, stereo, or multi-channel power amplifier 802. Individual line feeds 803 travel from the amplifier 802 to each individual piece of piezoelectric tactile acoustic material 804 of the probe assembly 100, such as any one of the aforementioned probe assemblies 100a, 100b, 100c, 100d, 100e, and 100f. To enable stereo or multi-channel applications, each component requires its own feed.

[0073] FIG. 9 shows a three-dimensional view of the proximal distal end of an example transrectal ultrasound probe 101g probe assembly 100g with two tissue-contacting piezoelectric bars 108g embedded in the form of a ring, whereby the piezoelectric rings provide mono or stereo vibration fields for use in medical imaging methods such as echocardiography, crawling waves, and elastography and viscoelastography. Transrectal probes are used to examine the rectum and nearby structures, including the prostate, for abnormalities. They are also referred to as endorectal ultrasound (ERUS) and transrectal ultrasound (TRUS). Transrectal probes are most commonly inserted into the rectum to examine the prostate. Embedding a piezoelectric acoustic frequency vibration driver in the transrectal probe allows for the entire process of elastography at the point of contact within the body, for example, for diagnosing prostate cancer.

[0074] FIG. 10 shows side views of two exemplary probe assemblies 100h and 100i, which include alternative piezoelectric bar transducers embedded in transrectal probes. Probe assembly 100h shows a vibration device 108h consisting of two parallel bars of tissue-contacting piezoelectric material arranged parallel to ultrasound array 102h. Probe assembly 100i shows a vibration device 108i consisting of a series of piezoelectric tissue-contacting "buttons" (small circular piezoelectric components) surrounding ultrasound array 102i. This method enables multi-source / multi-channel piezoelectric bar-based vibration sources, which can be used for elastography methods such as echoelastography and viscoelastography, whereby multiple vibration sources can be used to generate multidirectional shear wave fields as well as other useful types of shear wave fields.

[0075] Figure 11 shows an example of a linear ultrasound probe 100j (non-transrectal) with a vibration device 108j consisting of a series of piezoelectric "buttons" (small, often circular piezoelectric components) surrounding an ultrasound array 102j. This method allows for a multi-source / multi-channel piezoelectric bar-based vibration source and can be used to generate a variety of shear wave fields, including multi-directional shear wave fields (reverberation waves, crawling waves, etc.). When the number of piezoelectric buttons substantially matches the number of ultrasound elements, this method can also be used for elastography methods such as acoustic radiation force impulse (ARFI) and its derivatives, such as focused vibration phased array techniques for ultrasound scanning imaging (SSI).

[0076] 12 is a block diagram of an ultrasound elastography diagnostic apparatus 1200 including a probe assembly 1202 including an ultrasound probe 1204 with an ultrasound device or device array 1206 configured to detect vibrations passing through subject tissue 1207. The probe assembly 1202 includes a snap-on molded boot component 1208. The snap-on boot component 1208 includes one or more vibration devices 1210 and a vibration-damping material for isolating the ultrasound device 1206 from vibrations induced by the vibration devices 1210. The probe assembly 1202 includes an input electrical interface 1212 communicatively coupled to a signal generator 1214 to receive a vibration drive signal 1216 comprising one of (i) an acoustic radiation force impulse (ARFI) signal and (ii) an external vibration shear wave elastography imaging (EV-SWEI) signal. The input electrical interface 1212 is communicatively coupled to the one or more vibration devices 1210 to generate a corresponding one of an ARFI push pulse and an EV-SWEI vibration 1218. The probe assembly 1202 includes an output electrical interface 1220 communicatively coupled to the ultrasound probe 1204 that receives tissue echoes 1222 from the subject tissue 1207 after each ultrasound transmission for tracking tissue displacement. The output electrical interface 1220 can be communicatively coupled to an image processor 1224 that processes the tissue echoes into tissue displacement and then into one or more viscoelastic properties that can be displayed as one or more maps 1226 on a display.

[0077] In one or more embodiments, the one or more vibration devices 1210 include one or more piezoelectric bars. In one or more embodiments, 1208 is an overmolded boot attached to the ultrasound probe 1204. In one or more embodiments, the ultrasound elastography diagnostic apparatus 1200 is communicatively coupled to or includes a signal generator 1214 and an image processor 1224. In one or more embodiments, the signal generator 1214 is configured to generate an ARFI signal. The image processor 1224 is configured to map one or more viscoelastic properties derived from the received tissue echoes 1222 resulting from the ARFI signal. In one or more embodiments, the signal generator 1214 is configured to generate an EV-SWEI signal. The image processor 1224 is configured to map one or more viscoelastic properties derived from the received tissue echoes 1222 resulting from the EV-SWEI signal.

[0078] In one or more embodiments, the image processor 1224 is configured to determine one or more viscoelastic properties of a body region of a living subject at a plurality of points within the body region by: (i) establishing a shear wave field within the body region; (ii) measuring properties of the shear wave field at each of the plurality of points; (iii) calculating a rate of change of the property with respect to positional change within the body region at each of the plurality of points; and (iv) determining one or more viscoelastic properties of the body region at the plurality of points from the calculated rate of change at each of the plurality of points. In one or more specific embodiments, the image processor 1224 is further configured to create a shear wave field within the body region using at least one vibration source. In one or more specific embodiments, the one or more viscoelastic properties comprise at least one of stiffness, dispersion, and viscosity. In one or more specific embodiments, the signal generator 1214 generates vibration signals configured to impart shear-induced vibrations transmitted at a plurality of frequencies to the body region.

[0079] FIG. 13 is a flow diagram of a method 1300 for manufacturing an ultrasound elastography diagnostic device. In one or more embodiments, the method 1300 includes attaching one or more vibration devices (e.g., one or more piezoelectric bars) to a vibration isolation component (block 1302). The method 1300 also includes forming a probe assembly by attaching the vibration isolation component to an ultrasound probe configured to detect vibrations passing through subject tissue (block 1304). The method 1300 also includes communicatively coupling an input electrical interface to one or more vibration devices configured to generate at least one of (i) acoustic radiation force impulse (ARFI) push pulses and (ii) external vibration shear wave elastography imaging (EV-SWEI) vibrations (block 1306). The method 1300 also includes communicatively coupling an output electrical interface to the ultrasound probe (block 1308). The method 1300 includes communicatively coupling the input electrical interface to a signal generator configured to generate a corresponding one of an ARFI push pulse and an EV-SWEI vibration (block 1310). The method 1300 includes communicatively coupling the output electrical interface to an image processor configured to generate a map of one or more viscoelastic properties included in information received by the ultrasound probe (block 1312). Thereafter, the method 1300 ends.

[0080] FIG. 14 is a flow diagram of a method 1400 for performing an ultrasound elastography diagnostic procedure. In one or more embodiments, the method 1400 includes positioning a probe assembly in contact with a subject's tissue (block 1402). The probe assembly includes (i) an ultrasound probe configured to detect vibrations passing through the subject's tissue, (ii) a vibration isolation component, and (iii) one or more vibration devices coupled to the ultrasound probe via the vibration isolation component. The one or more vibration devices are configured to generate at least one of (a) an acoustic radiation force impulse (ARFI) push pulse and (b) an external vibration shear wave elastography imaging (EV-SWEI) vibration. The method 1400 includes transmitting one of an ARFI signal and an EV-SWEI signal to the one or more vibration devices to generate a corresponding one of the ARFI push pulse and the EV-SWEI vibration (block 1404). The method 1400 includes detecting, using an ultrasound probe, a tracked vibration waveform resulting from a corresponding one of an ARFI push pulse or an EV-SWEI vibration (block 1406). The method 1400 includes mapping, in an image processor, one or more viscoelastic properties derived from the tracked vibration waveform (block 1408). The method 1400 then ends.

[0081] In one or more embodiments, the method 1400 may further include generating an ARFI signal and mapping one or more viscoelastic properties derived from the vibration waveform tracked from the ARFI signal.

[0082] In one or more embodiments, the method 1400 may further include generating an EV-SWEI signal and mapping one or more viscoelastic properties derived from the oscillatory waveform tracked from the EV-SWEI signal.

[0083] In one or more embodiments, method 1400 may further include determining one or more viscoelastic properties of a body region of a living subject at a plurality of points within the body region by: (i) establishing a shear wave field within the body region; (ii) measuring properties of the shear wave field at each of the plurality of points; (iii) calculating a rate of change of the properties with respect to positional change within the body region at each of the plurality of points; and (iv) determining one or more viscoelastic properties of the body region at the plurality of points from the calculated rate of change at each of the plurality of points.

[0084] In one or more particular embodiments, the method 1400 may further include creating a shear wave field within the body region. In one or more particular embodiments, the one or more viscoelastic properties comprise at least one of stiffness, dispersion, and viscosity.

[0085] First, the present disclosure provides, in one or more embodiments, an acoustic radiation force impulse (ARFI) ultrasound elastography diagnostic device in which the two functions of ARFI (push pulse and tracking) are split into two separate hardware systems, but both are housed within the same device (probe).

[0086] Second, in another aspect of the present disclosure, a method is provided for using an Acoustic Radiation Force Impulse (ARFI) ultrasound elastography system, in which the two functions of ARFI (push pulse and tracking) are split into two separate hardware systems, but both are housed within the same device (probe).

[0087] Third, in an additional aspect of the present disclosure, an acoustic radiation force impulse (ARFI) ultrasound elastography diagnostic device is provided, in which the two functions of ARFI (push pulse and tracking) are split into two separate hardware systems, with the tracking function hardware being a standard ultrasound diagnostic probe and the ARFI push pulse hardware being a molded boot that is attached to the standard ultrasound diagnostic probe, thereby integrating both functions for operation.

[0088] Fourth, in a further aspect of the present disclosure, a method of using an acoustic radiation force impulse (ARFI) elastography system is provided, wherein the two functions of ARFI (push pulse and tracking) are split into two separate hardware systems, with the tracking function hardware being a standard ultrasound diagnostic probe and the ARFI push pulse hardware being embedded in a molded boot that is attached to the standard ultrasound diagnostic probe, thereby integrating both functions for operation.

[0089] Fifth, in yet another aspect of the present disclosure, an external vibration ultrasound elastography device is provided, in which an external vibration system is integrated with an ultrasound probe.

[0090] Sixth, in yet an additional aspect of the present disclosure, there is provided a method of using an external vibration ultrasound elastography device, wherein the external vibration system is integrated with an ultrasound probe.

[0091] Seventh, in yet a further aspect of the present disclosure, an external vibration ultrasound elastography device is provided, in which the external vibration system is embedded in a molded boot that is attached to a standard ultrasound diagnostic probe, thereby integrating both the external vibrator and the ultrasound probe for operation.

[0092] Eighth, in another additional aspect of the present disclosure, a method of using an external vibration ultrasound elastography device is provided, wherein the external vibration system is embedded in a molded boot that is attached to a standard ultrasound diagnostic probe, thereby integrating both the external vibrator and the ultrasound probe for operation.

[0093] Ninth, in one or more embodiments of the second, fourth or sixth aspect, the method comprises measuring viscoelastic properties of a body region of a living subject at a plurality of points within the body region, and comprises the steps of: (i) establishing a shear wave field within the body region; (ii) measuring properties of the shear wave field at each of the plurality of points; (iii) calculating a rate of change of the properties with respect to positional change within the body region at each of the plurality of points; and (iv) determining the viscoelastic properties of the body region at the plurality of points from the calculated rate of change at each of the plurality of points.

[0094] Tenth, in certain embodiments of the ninth aspect, the establishing step may include creating a shear wave field in the body region using at least one vibration source.

[0095] Eleventh, in certain embodiments of the tenth aspect, the viscoelastic property is stiffness or dispersion.

[0096] Twelfth, in a very particular embodiment of the eleventh aspect, the establishing step comprises subjecting the body region to shear-inducing vibrations transmitted at multiple frequencies.

[0097] Thirteenth, in a further additional aspect of the present disclosure, a system comprises an apparatus according to the first, third, or fifth aspect above, and further comprises an image processor configured to provide a map of one or more viscoelastic properties of each of a plurality of points within a region of interest.

[0098] It is further contemplated that the probes of the present system can be used in conjunction with other types of intracavity probes. For example, endoscopic devices for imaging with the present system can include various types of devices, such as TEE, transnasal, transvaginal, transrectal, and intracavity devices (transducers with a shaft carrying an ultrasound array that moves the array to contact or approach a target for treatment, such as a mass, and inserted through a natural or surgically created orifice). Endoscopic devices for imaging with the present system can be controlled manually and / or automatically, including manual / automatic control from a remote location, i.e., remote from the treatment site, with the controller and associated devices, such as a display, I / O devices, and memory, operably connected to a local controller or processor through a network such as the Internet. Control signals and other signals, including image signals, can be transmitted and received by any means, for example, wired or wireless.

[0099] It should be noted that various embodiments may be implemented in hardware, software, or a combination thereof. Also, various embodiments and / or components, such as modules, or their components and controllers, may be implemented as part of one or more computers or processors. The computer or processor may include a computing device, an input device, a display unit, and an interface, for example, for accessing the Internet. The computer or processor may include a microprocessor. The microprocessor may be connected to a communication bus. The computer or processor may further include memory. The memory may include random access memory (RAM) and read-only memory (ROM). The computer or processor may further include a storage device, which may be a hard disk drive or a removable storage drive such as a solid-state drive or optical disk drive. The storage device may also be other similar means for loading computer programs or other instructions into the computer or processor.

[0100] As used herein, the terms "computer," "subsystem," or "module" may include processor-based or microprocessor-based systems, including systems using microcontrollers, reduced instruction set computers (RISC), ASICs, logic circuits, and other circuits or processors capable of performing the functions described herein. The above examples are merely illustrative and are not intended to limit the definition and / or meaning of the term "computer."

[0101] A computer or processor executes a set of instructions stored in one or more memory devices to process input data. The memory devices may also store data or other information as desired or required. The memory devices may be in the form of information sources or physical memory devices within a processing machine.

[0102] The set of instructions may include various commands that instruct a computer or processor as a processing machine to perform certain operations, such as the methods and processes of various embodiments. The set of instructions may be in the form of a software program. The software may be in various forms, such as system software or application software, and may be embodied as a tangible and non-transitory computer-readable medium. Further, the software may be in the form of a collection of separate programs or modules, a program module within a larger program, or a portion of a program module. The software may also include modular programming in the form of object-oriented programming. The processing of input data by the processing machine may be in response to operator commands, or in response to results of previous processing, or in response to requests made by another processing machine.

[0103] As used herein, a structure, constraint, or element that is "configured to" perform a task or operation is specifically structurally shaped, constructed, or adapted in a manner corresponding to the task or operation. For clarity and avoidance of doubt, an object that can simply be modified to perform a task or operation is not "configured to" perform a task or operation as used herein. Instead, as used herein, the use of "configured" indicates a structural fit or characteristic, or structural requirement of the structure, constraint, or element being described as "configured to" perform a task or operation. For example, a controller circuit, processor, or computer "configured to" perform a task or operation may be understood as being specifically configured to perform the task or operation (e.g., having one or more programs or instructions stored or associated therewith that are adapted or intended to perform the task or operation, and / or having an arrangement of processing circuitry that is adapted or intended to perform the task or operation). For purposes of clarity and avoidance of doubt, a general-purpose computer (which, if properly programmed, may be "configured to perform" a task or operation) is not "configured to perform" a task or operation unless and until it is specifically programmed or structurally modified to perform the task or operation.

[0104] As used herein, the terms "software" and "firmware" are used interchangeably and include computer programs stored in memory for execution by a computer, including RAM memory, ROM memory, EPROM memory, EEPROM memory, and non-volatile RAM (NVRAM) memory. The above memory types are merely exemplary and thus do not limit the types of memory that can be used to store computer programs.

[0105] The transmit step requires transmitting at least one ultrasound signal with sufficient power to allow the signal to propagate through the target tissue. Typically, the transmit signal is reflected at the interface separating two layers with different water and biomaterial contents. Any suitable frequency described herein, in the future, or known in the art can be used. The frequency used can be selected for maximum transmission and reflection performance and lowest noise by recording signals from the tissue at different frequencies. Thus, a frequency with the best properties can be selected for a particular tissue, and a dedicated probe can be constructed using such a frequency. Desirably, the transmit step is performed using multiple signals. Multiple signals can be transmitted and return signals ("echoes") from the reflecting interface can be recorded. Signal averaging improves measurement accuracy and can be performed over a relatively short period of time. Typically, multiple signals for signal averaging are transmitted over a period of less than 1-2 seconds, more often less than 100-300 milliseconds, and preferably less than 50 milliseconds. Optionally, the transmit step can be performed using multiple signals over a longer period not normally used for signal averaging. A-, B-, or C-scan modes of ultrasound examination and recording can be used with the methods and devices of the present invention. The present invention can be applied to a variety of application sites and medical procedures described herein, developed in the future, or known in the art. The present invention can also be used with different types of suitable probes, systems, and methods for ultrasound measurement and calculation and biological standards described herein, developed in the future, or known in the art.

[0106] Signals received by the detector may be subjected to threshold processing. Typically, threshold processing filters out signals at a predetermined value or range of values. In some cases, signal processing may filter out signals above or below a predetermined threshold. Predetermined signal thresholds may include: 1) predetermined values ​​correlated with or selected from anatomical sites and structures (e.g., estimates of actual thickness); 2) predetermined values ​​generated from examination of the tissue under examination (e.g., generating an average value for the tissue under examination); and 3) predetermined values ​​generated from the tissue being examined to determine normative values ​​for different tissues, subject populations, disease states, etc. (e.g., generating an average value from a particular anatomical site or structure using multiple qualified subjects). A system or detector may filter out signals at different levels of signal detection or processing. For example, signals may be filtered out by time gating, electronic filtering, digital filtering, analog filtering, and amplitude gating.

[0107] The signal, the calculation results, or the signal processing may be displayed on a digital or analog display for viewing by an operator or subject. The display may further include a predetermined display layout including symbols or illustrations indicating preselected anatomical properties of the examined tissue. The calculation results may then be used graphically to display calculated distances (or other suitable information) related to the predetermined anatomical properties.

[0108] While the present disclosure has been described with reference to exemplary embodiments, those skilled in the art will recognize that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular system, device, or component to the teachings of the present disclosure without departing from the essential scope of the present disclosure. Therefore, the present disclosure is not limited to the particular embodiments disclosed for carrying out the disclosure, but is intended to include all embodiments falling within the scope of the appended claims. Furthermore, the use of terms such as first, second, etc. does not denote any order or importance; rather, terms such as first, second, etc. are used to distinguish one element from another.

[0109] As used in this specification and claims, the phrase "at least one" when used in reference to a list of one or more elements should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of every element specifically listed in the list of elements, and not excluding any combination of elements in the list of elements. This definition also allows for elements other than those specifically identified in the list of elements to which the phrase "at least one" refers may optionally be present, whether or not related to those specifically identified elements.

[0110] All patents, patent applications, published patent applications, and other materials, such as articles, books, specifications, publications, documents, and objects, referenced herein are incorporated by reference in their entirety for all purposes, except for any prosecution file history related thereto, anything that contradicts or conflicts with the present specification, or anything that may have a limiting effect on the broadest scope of any claims now or in the future related hereto. By way of example, in the event of a conflict or inconsistency between the explanations, definitions, and / or term usage associated with any of the incorporated materials and those associated with the present specification, the explanations, definitions, and / or term usage in the present specification shall control.

[0111] The description of the present disclosure has been presented for purposes of illustration and description and is not intended to be exhaustive or limited to the disclosed form. Many modifications and variations will be apparent to those skilled in the art without departing from the scope of the present disclosure. The described embodiments have been chosen and described to best explain the principles and practical applications of the present disclosure and to enable those skilled in the art to understand the disclosure in various embodiments with various modifications as suited to the particular uses envisioned.

Claims

1. An ultrasound elastography diagnostic device, a probe assembly, the probe assembly comprising: an ultrasound probe configured to detect vibrations passing through the subject's tissue; a vibration isolation component; one or more vibration devices coupled to the ultrasonic probe via the vibration isolation component; an input electrical interface communicatively coupleable to a signal generator and configured to receive a vibration drive signal comprising one of (i) an acoustic radiation force impulse (ARFI) signal, or (ii) an external vibration shear wave elastography imaging (EV-SWEI) signal, the input electrical interface communicatively coupled to the one or more vibration devices for generating a corresponding one of the ARFI push pulse or the EV-SWEI vibration; an output electrical interface communicatively coupled to the ultrasound probe, the output electrical interface communicatively coupled to an image processor for tracking tissue displacements and generating a map of one or more viscoelastic properties contained in the tracked tissue displacements.

2. The ultrasound elastography diagnostic apparatus of claim 1 , wherein the one or more vibration devices comprise one or more piezoelectric bars.

3. The ultrasound elastography diagnostic apparatus of claim 1 , wherein the vibration device and isolation component are combined within an overmolded boot that is attached to the ultrasound probe.

4. The ultrasound elastography diagnostic apparatus according to claim 1 , further comprising the signal generator and the image processor.

5. the signal generator is configured to generate the ARFI signal; The ultrasound elastography diagnostic apparatus of claim 4 , wherein the image processor is configured to map the one or more viscoelastic properties derived from displacements of the tracked tissue resulting from ARFI signals.

6. the signal generator is configured to generate the EV-SWEI signal; 5. The ultrasound elastography diagnostic apparatus of claim 4, wherein the image processor is configured to map the one or more viscoelastic properties derived from the displacement of the tracked tissue resulting from the EV-SWEI signal.

7. The ultrasonic elastography diagnostic apparatus according to claim 4, the image processor measures the one or more viscoelastic properties of a body region of a living subject at a plurality of points within the body region; establishing a shear wave field within the body region; measuring a characteristic of the shear wave field at each of the plurality of points; calculating, at each of the plurality of points, a rate of change of the characteristic with respect to positional change within the body region; and determining one or more viscoelastic properties of the body region at the plurality of points from the calculated rate of change at each of the plurality of points.

8. The ultrasound elastography diagnostic apparatus of claim 7 , wherein the image processor is further configured to establish a shear wave field within the body region using at least one vibration source.

9. The ultrasound elastography diagnostic apparatus of claim 8 , wherein the one or more viscoelastic properties comprise at least one of stiffness, elasticity, viscosity, attenuation, wave velocity, phase angle, and frequency dispersion.

10. The ultrasound elastography diagnostic apparatus of claim 8 , wherein the signal generator generates the vibration signal configured to subject the body region to shear wave-induced vibrations transmitted at multiple acoustic frequencies.

11. 1. A method for manufacturing an ultrasound elastography diagnostic device, comprising: attaching one or more vibration devices to a vibration isolation component; forming a probe assembly by attaching the vibration isolation component to an ultrasound probe configured to detect vibrations passing through subject tissue; communicatively coupling an input electrical interface to the one or more vibration devices configured to generate at least one of (i) acoustic radiation force impulse (ARFI) push pulses, or (ii) external vibration shear wave elastography imaging (EV-SWEI) vibrations; communicatively coupling an output electrical interface to the ultrasound probe.

12. communicatively coupling the input electrical interface to a signal generator configured to generate a corresponding one of the ARFI push pulse or the EV-SWEI oscillation; 12. The method of claim 11, further comprising: communicatively coupling the output electrical interface to an image processor configured to generate a map of one or more viscoelastic properties from the information contained in the data received by the ultrasound probe.

13. The method of claim 11 , wherein the one or more vibration devices comprise one or more piezoelectric bars.

14. 1. A method of performing an ultrasound elastography diagnostic procedure, comprising: positioning a probe assembly in contact with a subject's tissue, the probe assembly comprising: (i) an ultrasound probe configured to detect vibrations passing through the subject's tissue; (ii) a vibration isolation component; and (iii) one or more vibration devices coupled to the ultrasound probe via the vibration isolation component and configured to generate at least one of: (a) an acoustic radiation force impulse (ARFI) push pulse; or (b) an external vibration shear wave elastography imaging (EV-SWEI) vibration; transmitting one of an ARFI signal or an EV-SWEI signal to the one or more vibration devices to generate a corresponding one of the ARFI push pulse or the EV-SWEI vibration; tracking, by the ultrasound probe, the displacement of the tissue resulting from the corresponding one of the ARFI push pulse or the EV-SWEI vibration; mapping, in an image processor, one or more viscoelastic properties derived from the tracked tissue displacements.

15. generating the ARFI signal; 15. The method of claim 14, further comprising mapping the one or more viscoelastic properties derived from the displacements of the tracked tissue resulting from the ARFI signals.

16. generating the EV-SWEI signal; 15. The method of claim 14, further comprising mapping the one or more viscoelastic properties derived from the displacements of the tracked tissue resulting from the EV-SWEI signals.

17. measuring the one or more viscoelastic properties of a body region of a living subject at a plurality of points within the body region; establishing a shear wave field within the body region; measuring a characteristic of the shear wave field at each of the plurality of points; calculating, at each of the plurality of points, a rate of change of the characteristic with respect to positional change within the body region; 15. The method of claim 14, further comprising determining one or more viscoelastic properties of the body region at the plurality of points from the calculated rate of change at each of the plurality of points.

18. The method of claim 17 , further comprising creating a shear wave field within the body region.

19. 20. The method of claim 18, wherein the one or more viscoelastic properties comprise at least one of stiffness, elasticity, viscosity, damping, wave velocity, phase angle, and frequency dispersion.

20. 20. The method of claim 18, further comprising subjecting the body region to shear-induced vibrations transmitted at multiple frequencies.

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