Clothing with ultrasonic imaging sensors

Abstract

In garments having ultrasound sensors placed on a patient's body, problems associated with poor contact between the ultrasound sensors and the area being imaged are solved by using feedback to improve the poor contact and / or by eliminating transceivers with poor radiation patterns.

Description

[Technical Field]

[0001] The present invention relates generally to ultrasound imaging, and more particularly to a garment with ultrasound sensors that is placed on a patient's body and that can acquire ultrasound images of a body part without the use of gel, water, or other non-solid coupling media. [Background technology]

[0002] Ultrasound (US) is one of the most widely used medical imaging modalities. It is primarily used for imaging soft tissue and is considered safe. Modern ultrasound systems consist of an ultrasound pod or transducer that transmits and receives ultrasound signals, and associated hardware that analyzes the received or reflected signals to generate images. Medical ultrasound typically operates at frequencies between 3 MHz and 15 MHz, although older models operate as high as 1 MHz.

[0003] One of the key issues is maintaining good ultrasonic contact between the US pod and the patient's skin. In more scientific terms, good contact means that most of the energy output from the US pod is delivered to the patient's body with little or no delay. In engineering terms, good ultrasonic contact means that there is no air between the US pod and the body and that there is good impedance matching between the US pod and the patient's body.

[0004] A typical US transducer is made of an array containing many small US emitters / receivers. These emitters are operated in a very specific mode (like a phased array) to emit a focused beam onto the patient's body. To generate the focused beam, the US system uses precise timing to activate the individual emitters in the US pod. Good ultrasonic contact between the pod and the patient results in good performance of the US system. However, if the US array in the pod does not achieve sufficient ultrasonic contact with the patient's body, the focused beam will not form and image acquisition will be impossible or significantly degraded. Achieving good ultrasonic contact over the entire area of a US pod, which is approximately 70 mm x 25 mm or larger, is extremely difficult without a coupling medium.

[0005] Standard US solves the problem of "good ultrasound contact" by using a matching layer deposited on the body-facing surface of the US pod and a gel that removes air from the gap between the US pod and the patient's body / skin. This is why the patient's body is covered with a large amount of gel during US procedures. This gel fills the gap between the pod and the body, ensuring good ultrasound contact even if the patient's size does not allow the entire US pod to be in direct contact with the patient's body.

[0006] Over the past decade, there has been significant interest in new ultrasound imaging modalities. These new techniques use multiple ultrasound transceivers positioned over a wide area of the body, sometimes even around the body. This new mode of ultrasound transceiver is much smaller than a standard US pod (less than 10 x 10 mm) and covers a much larger body area compared to traditional medical US. Unlike traditional US, which uses a focused beam, reflection, and time-of-flight parameters to generate images, the new modality uses reflection, transmission, and refraction to extract more physical data and produce much clearer 3D images.

[0007] However, the problem of ensuring good ultrasound contact remains. Without good ultrasound contact, the new modalities cannot produce adequate images. Unlike older US methods, new imaging modalities must cover the entire body, not just a limited area, making the use of gels or other liquid materials highly undesirable. Summary of the Invention

[0008] To solve the problems associated with poor contact between an ultrasound sensor and the part being imaged and / or to eliminate transceivers with poor radiation patterns, the present invention seeks to provide a garment in which an ultrasound sensor can be placed on a patient's body and ultrasound images of the body part can be obtained, and to improve contact by using feedback, as described in more detail below.

[0009] One embodiment includes multiple transceivers embedded on the patient's body, either individually or in a large patch, or in clothing that is stretchy and tends to conform to the shape of the patient's body, which may be in the form of a belt, hat, sleeves, vest, shirt, pants, or any combination thereof.

[0010] Unlike conventional US, which images a single organ, the present invention provides a novel imaging modality that images an entire body part (e.g., abdomen, pelvis, extremities, neck) rather than a specific organ within the body part. [Brief explanation of the drawings]

[0011] The present invention will be more fully understood from the following detailed description when read in conjunction with the drawings. [Figure 1] Figure 1A is a diagram of a prior art ultrasound emitter assembly and ultrasound sensor assembly placed on one side of a subject. Figure 1B is a diagram of a prior art ultrasound emitter assembly, showing that when air is present between the emitter and the subject's surface (skin), most of the signal is reflected very quickly with a 180° phase reversal. [Figure 2]2A-2D are simplified diagrams of examples of frequency dependent transmission (frequencies 2A>2B>2C>2D) according to non-limiting embodiments of the present invention. [Figure 3] 3A-3D are simplified diagrams of examples of frequency dependent transmission (frequencies 2A>2B>2C>2D) where air pockets are observed within the body, according to non-limiting embodiments of the present invention. [Figure 4] Figure 4A is a simplified diagram of the radiation pattern from an emitter in the absence of a small attenuator, and Figure 4B is a simplified diagram of the radiation pattern from an emitter in the presence of a small attenuator in the body. [Figure 5] FIG. 5 is a simplified diagram of a measurement of a reflected signal (or surface wave) measured using at least two parts A and B of adjacent emitters of the same transceiver. DETAILED DESCRIPTION OF THE INVENTION

[0012] Referring to Figure 1A, on one side of a subject 2 is an ultrasound emitter assembly 1 and an ultrasound sensor assembly 3. Local reflection occurs when an ultrasound-blocking material (such as air) completely separates all or most of the emitter area from the patient's body.

[0013] In this mode, a high-frequency (e.g., 5 MHz) pulse is emitted and the immediate / short-term reflection is measured at the emitter. If ultrasonic contact is good, the signal propagates into the test object, and reflections occur at surfaces at least 5 mm from the emitter and are very low. In this case, the first returning signal arrives a few microseconds after the test pulse is emitted, with an intensity of a few percent of the emitted signal.

[0014] As shown in Figure 1B, when air is present between the emitter and the subject's surface (skin), most of the signal is reflected at high speed with a 180° phase reversal.

[0015] 2A-2D, examples of frequency dependent transmissions used in embodiments of the present invention are shown.

[0016] Frequency-dependent transmission occurs when the volume of the material (e.g., air) that blocks ultrasonic waves is sufficient to allow a low-frequency signal to penetrate the patient's body but reflect a high-frequency signal locally.

[0017] In this mode, attenuation information collected at multiple frequencies from multiple sensors not located at the emitter position is used to estimate the quality of ultrasonic contact.

[0018] When the emitter's radiation pattern is very narrow and the emitted waveform passes through soft tissue, there are sensors that can receive the signal. However, when the pressure wave hits an attenuation layer such as air (lungs, intestines, etc.), the signal is significantly attenuated and cannot be detected by the sensors.

[0019] However, when the same emitter operates at a lower frequency, when a lower-frequency wave is transmitted from the same aperture, its radiation pattern becomes wider. As the operating frequency decreases, the radiation pattern, more specifically the radiation angle, becomes wider, and for the same emitter, more sensors can receive the emitted signal.

[0020] Figures 2A - 2D show an emitter 8 that emits ultrasonic signals whose operating frequencies F1 - F4 (F1 > F2 > F3 > F4) decrease in order. It can be seen that as the frequency decreases, more sensors 10 can receive the emitted signal.

[0021] Figures 3A - 3D show an emitter 8 that emits the same ultrasonic signals at the same operating frequencies F1 - F4, but there is an air pocket 11 in the body. As the radiation angle increases (as the frequency decreases), more sensors 10 can sense the transmitted signal.

[0022] If the group of sensors that receive the signal when using F1 is Gf1, the group of sensors that receive the signal when using F2 is Gf2..., when the ultrasonic contact at the emitter point is good, it can be assumed that Gf1 <= Gf2 <= Gf3 < Gf4.

[0023] Gf1 can be zero if the narrow beam hits an area with high attenuation (such as the lungs), but as the frequency decreases, the radiation angle increases, so there will be sensors that receive the signal.

[0024] Case #1: Gf1 or {Gf1 and Gf2} is 0, and Gf3 and Gf4 are not 0. This is a weak ultrasonic contact, and local "pushing" can strengthen the local ultrasonic contact.

[0025] Case #2: Gf1 or {Gf1 and Gf2} or {Gf1, Gf2 and Gf3} is 0 and Gf4 is not 0. This may indicate that the ultrasonic contact is very weak and may be improved by localized pressing.

[0026] Case #3: Gfi is all 0. This may indicate a bad transmitter or a localized blockage.

[0027] The problem of local small attenuators in the body will now be explained with reference to Figures 4A and 4B. Figure 4A shows radiation pattern 12 from emitter 8 when no small attenuators are present. Figure 4B shows radiation patterns 14 and 16 from emitter 8 with a small attenuator 18 present in the body.

[0028] A small local attenuator is an attenuator that interferes with the radiated wave within the near-field range and distorts its spatial pattern.

[0029] When the inversion process occurs, the software simulates the propagating wave using an inverted model of the emitter. However, if the attenuation significantly changes the radiation pattern (as in Figure 4B), the impact on the inversion process can be severe.

[0030] Minor attenuation can be in the form of small air bubbles, which cause part of the signal to pass through and be reflected from deeper layers, and part to be reflected from the bubble itself. This does not result in a significant loss of signal, but rather a change in the radiation pattern. To avoid this, at least two parts, A and B, of adjacent emitters on the same transceiver are used to measure the reflected signal (or surface wave), as shown in Figure 5. The system first transmits from part A and analyzes the signal received at part B, and then does the reverse. If small air bubbles are present, the reflection patterns received at parts A and B are expected to be significantly different. If the reflection patterns of two different areas within the transceiver are significantly different, the particular transceiver is excluded from image processing.

[0031] The present invention overcomes the problem of ultrasonic contact without the use of coupling agents. For example, in one embodiment, multiple ultrasonic frequencies are used to determine the quality of ultrasonic contact. The system performs a "contact test" by starting at the highest operating frequency (e.g., 1-2 MHz), emitting a pulse from each transceiver, recording the signal received by all other transceivers, and counting the number of transceivers that receive the signal. After the highest frequency test, the test is repeated at lower frequencies down to a range of 20-300 KHz.

[0032] A transceiver that fails to communicate with other transceivers on all frequencies tested (all Gfi's are 0) is declared "bad."

[0033] The transceiver that can communicate with other transceivers on the highest frequency is declared "superior."

[0034] Transceivers that test well at some low frequencies but poorly at higher frequencies are flagged for "manual intervention" to improve ultrasonic contact.

[0035] If, after manual intervention, the transceiver still indicates ultrasonic contact at low frequencies but not at high frequencies, a "problem" is flagged in the analysis software.

[0036] This selection process is based on the physical fact that air attenuation is very large for 1MHz signals (~100-150dB / m) but is much smaller in the 30-80KHz range (~0.5dB / m), and signals must pass through small air gaps to reach the skin.

[0037] Note that there are also physical issues with reflections, but these are ignored at this point.

[0038] In one embodiment, "bad" transceivers can be excluded from the scanning / imaging process.

[0039] In one embodiment, unlike standard US systems, an unfocused light source is used to scan the body part: no timing relationship between different transceivers is required and they can be operated sequentially, in parallel, in groups, etc.

[0040] As part of the scanning process, any transceiver that does not exhibit ultrasonic contact at both the highest and lowest frequencies is determined to be a "bad" transceiver and is flagged by the imaging system not to be used in scanning and imaging operations.

[0041] Additionally, transceivers with significant differences in the reflection patterns received from two adjacent sections of the same transceiver are excluded from the scanning and imaging process.

[0042] This is not done in prior art US systems, which use all elements (pixels) of the US array to generate a focused beam. In one embodiment, feedback regarding the position of the transceiver and areas of "almost good" ultrasound contact may be provided to the patient or healthcare provider to guide them in improving the quality of contact.

[0043] If the transceiver is determined to be "bad" at the highest frequency and "good" at the lowest frequency, a signal can be sent to the patient or medical personnel to tap or press the relevant area and re-run the contact test.

Claims

1. 1. A system for improving skin contact of an ultrasound transceiver using feedback from an ultrasound sensor, comprising: a plurality of ultrasound transceivers attached to the skin of the patient; a software module that analyzes acoustic emission signal, reflection, and transmission data information after operation of each transducer at a plurality of ultrasonic frequencies; a software module for analyzing and comparing reflection patterns received by adjacent portions of the same transceiver; a classification system that analyzes the acoustic signal of each transceiver and rates the quality of skin contact; a real-time visual reference portion of the device that indicates the quality of the acoustic transmitted and reflected signals of each transceiver; and a system that provides user guidance or automation to adjust the contact of a particular area or a particular transceiver before re-evaluating skin contact.

2. The system of claim 1 , wherein the feedback is presented to each transceiver individually and is viewable by a user.

3. The system of claim 1 , wherein the visualization of the transceiver contacts is presented on a remote mobile phone or computer screen.

4. The system of claim 1 , wherein the user or automated system is guided to attach particular transceivers that receive a “medium” attachment score before re-evaluating attachment.

5. The system of claim 1 , wherein transceivers that receive a “bad” score or that exhibit different reflection patterns from two adjacent portions of the same transceiver are flagged for removal from imaging processing.

6. The system of claim 1 , wherein the transceiver is attached to the patient's skin without the use of gel, water, or other non-solid coupling medium.

7. A method for assessing transceiver skin ultrasound contact quality by receiving ultrasound signal feedback including reflected and transmitted waveforms from multiple transceivers and analyzing the acoustic input to classify ultrasound contact quality.

8. The method of claim 7 , wherein the feedback comprises local reflection measured at the location of the emitter.

9. The method of claim 7 , wherein the feedback comprises an attenuation signal received by at least one sensor not located at the emitter.

10. 8. The method of claim 7, wherein each transceiver emits at least two ultrasonic frequencies, one "high" frequency (greater than 700 KHz) and one lower frequency (20 Khz-700 KHz), and the system analyzes signals received by all transceivers in the system for each frequency.

11. A method for improving transceiver skin ultrasound contact quality by using ultrasound feedback analysis to adjust the adhesion of a particular transceiver with "poor quality contact," characterized in that the transceiver with "poor quality contact" lacks local reflections to the transmitting area and exhibits transmissions at some or all low frequencies to sensors not located at the emitter location.

12. 12. The method of claim 11, wherein the closeness of each of the "poor contact" transceivers is manually adjusted by a system user.

13. The method of claim 11, wherein the closeness of each of the "poor contact" transceivers is adjusted by an automated system.

14. A method for improving the quality of ultrasound imaging / ultrasound inversion processing by using ultrasonic feedback analysis to eliminate transceivers that exhibit significantly different reflection patterns in different adjacent areas of the same CMUT transmitting area.

15. A method for improving ultrasound imaging / ultrasound inversion processing by using feedback analysis to eliminate the use of transceivers that do not exhibit skin contact.

16. 16. The method of claim 15, wherein a transceiver that does not exhibit skin contact is defined as a transceiver that exhibits a local reflection at the emitter location along with a 180° phase reversal, or a transceiver that does not exhibit a local reflection and fails to communicate with other transceivers at all frequencies tested.

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