2aPAb – Ultrasound technology to remove kidney stones

Mohamed A. Ghanem – mghanem@uw.edu
Adam D.  Maxwell – amax38@uw.edu
Oleg A. Sapozhnikov – olegs@uw.edu
Michael R. Bailey – mbailey@uw.edu

University of Washington
1013 NE 40th St.
Seattle WA 98105

Popular version of 2aPAb – Designing an array for acoustic manipulation of kidney stones
Presented Tuesday morning, May 24, 2022
182nd ASA Meeting
Click here to read the abstract

Ultrasound technology is becoming an important treatment tool. For instance, sound waves can apply a radiation pressure that can displace an object. Multi-element arrays are complex ultrasound sources that consist of several small transducers that can be driven in sync or a specific order to output pressure waves with different shapes. Pressure wave shapes that have a doughnut shape or a long tube are useful as they can trap an object in the center and as we control the location of the doughnut the object follows. This technology can be used to trap small kidney stones or stone fragments and move them from the kidney collection areas toward the kidney exit without surgery. We have demonstrated the ability to move kidney stone models in the bladders transcutaneously in live pigs under anesthesia. We are currently designing a new multi-element array that will enable us to adapt this technology to move stones in the complex structure of the kidney over larger distances. This technology will reduce the surgery associated with kidney stone treatments by removing small stones or fragments before they become larger, which will lead to surgery, and eliminating emergency room visits by relieving blockages from these stones or fragments.

kidney stones

Controlled steering of kidney stones toward  the kidney exit with an ultrasound array.

2aBAb1 – Using ultrasound imaging to predict type1 diabetes development

Richard KP Benninger – richard.benninger@cuanschutz.edu
University of Colorado Anschutz medical campus
1775 Aurora Ct
Aurora, CO. 80045

Popular version of 2aBAb1 – Applying ultrasound phase-change contrast agents to guide therapeutic intervention in type 1 diabetes
Presented Tuesday morning, May 24th, 2022
182nd ASA Meeting
Click here to read the abstract

Type1 diabetes is an autoimmune disease in which the insulin-producing cells in the pancreas are destroyed. As a result people with type1 diabetes have to take insulin for the rest of their life. This is not a cure, and as well as the significant patient burden there are still risks for complications of diabetes that include eye, kidney and heart damage, as well as potentially falling into a coma from insulin overdose and low blood sugar. Strategies have been developed to prevent type1 diabetes through immune therapies that stop the destruction of insulin producing cells. Treatment early in the disease process, before significant destruction of insulin producing cells will be needed. However it is challenging to predict if an individual will get type1 diabetes and when, limiting the ability to intervene early.

Imaging approaches have been explored to detect the presence of autoimmune disease and concurrent inflammation in the pancreas, and loss of the insulin-producing cells. However there have been limited successes. A potential approach is based on the blood vessels become leaky during the autoimmune disease and inflammation in the pancreas. Thus small particles below 1um diameter can leak and accumulate in the diseased tissue. We have proposed to leverage the inherent advantages of ultrasound imaging that include deployability, cost-effectiveness and safety profile. Ultrasound contrast agents consist of gas filled bubbles (microbubbles). However the size of thee microbubbles means that they cannot access diseased tissue and are restricted to blood vessels. We have utilized a novel phase-change ultrasound contrast agent that consists of a condensed liquid droplet that is stable at body temperature and in circulation. However the acoustic beam from an ultrasound transducer can vaporize these droplets into microbubbles that provide ultrasound contrast. Thus these phase-change agents serve as circulating microbubble precursors that can access diseased tissue.

We tested whether these ultrasound phase change agents can access the injured tissue in the pancreas resulting from autoimmune disease, and whether accumulation of the contrast agents could be detected in ultrasound imaging. We found in pre-clinical models of type1 diabetes that significant accumulation of ultrasound phase change agents were observed in the pancreas, which was measurable by ultrasound (Figure 1). This accumulation correlated with the presence of autoimmune disease and decline in insulin-producing cells. Importantly the accumulation and ultrasound contrast was only present in the pancreas in models of diabetes: no accumulation was observed in non-diseased tissues. Further the accumulation of ultrasound phase change agents and ultrasound contrast correlated with the development of diabetes: models that developed diabetes rapidly or lacked therapeutic prevention showed a much higher contrast than those models that  developed diabetes slowly or showed therapeutic prevention of diabetes. Most importantly elevated contrast was measured very early in the disease process, earlier than the current gold standard measurement of circulating insulin autoantibodies.

diabetes

Figure 1: Conventional B-mode and contrast mode images before and after infusion and activation of phase-change ultrasound contrast agent. P=Pancreas, K=Kidney, S=Spleen.

As such the use of phase-change ultrasound contrast agents shows significant promise for detecting and tracking the presence of autoimmune disease and inflammation in the pancreas that heralds the development of type1 diabetes (Figure 2). Such a measurement would guide therapeutic intervention to prevent type1 diabetes, as well as assess the efficacy of such a treatment. Successful disease prevention will avoid the need for lifelong insulin therapy and complications of diabetes.

diabetes

Figure 2: Schematic illustrating use of phase-change ultrasound contrast agents to detect autoimmune disease in the pancreas.

5pBA4 – A noninvasive ultrasound device to treat urinary stones in pet cats

Adam Maxwell – amax38@uw.edu
Ga Won Kim – gawonkim@uw.edu
Elizabeth Lynch – elynch@apl.washington.edu
Brian MacConaghy – bmacconaghy@gmail.com
Eva Furrow – furro004@umn.edu
Jody Lulich – lulic001@umn.edu
Michael Borofsky – mborofsk@umn.edu
Michael R. Bailey – mbailey@uw.edu

Corresponding Author Address:
University of Washington
1013 NE 40th Street
Seattle, WA 98105

Popular version of 5pBA4 – A burst wave lithotripsy system for urinary stones in pet cats
Presented Friday, December 03, 2021
181st ASA Meeting, Seattle, WA
Click here to read the abstract

Like humans, cats grow stones in their kidneys. As these stones pass through the urinary tract, they can become stuck and block the outflow of urine. This obstruction can cause pressure in the kidney and may lead to kidney failure, pain, and other complications. Unfortunately, the minimally invasive technologies used in humans to break apart or remove stones can’t be used on a cat. A veterinarian’s only option for definitive treatment is a complex and costly surgery.

Our team has developed a new, noninvasive method to fragment kidney stones using a handheld ultrasound transducer placed against the skin of a patient. The ultrasound travels through the body and is focused onto a stone, were the high-amplitude pressure waves cause stresses that fracture the stone to pieces that are small enough to pass naturally through the urinary tract. This technology, called burst wave lithotripsy (BWL), has been demonstrated to be effective and safe in preclinical studies, and is now being tested in clinical trials in humans. The goal of this project was to adapt the technology to cats, so that we can provide a noninvasive option for treatment of their stones.

Because of the smaller anatomy of a cat vs. a human, the ultrasound transducer was scaled to a smaller size, and focused at a shorter depth from the skin where we anticipate the stones will be located. We also changed the ultrasound frequency emitted by the transducer. This characteristic controls the size of fragments remaining after the stone is broken apart. By using a higher frequency (650 kHz in cats vs. 350 kHz in humans), the stones are broken mostly into fragments less than 1 mm. Such fragments are usually small enough to pass through the ureter (the narrow tract between the kidney and bladder) and not obstruct urine flow.

BWL system designed for cats
Figure 1. The left image shows a BWL system designed for cats. The right image shows the small, handheld head of the therapy transducer, which is placed against the cat’s skin during a procedure.

We designed and built prototypes of the transducer and the electronics that power it. An ultrasound imaging probe was incorporated so a veterinarian or radiologist operating the system can use this imaging to target the stone before breaking it apart. The system was tested on natural feline stones in a benchtop experiment. Between 73-96% of the stone mass was reduced to fragments smaller than 1 mm, indicating a high probability of success in treatments.cat kidney stone

Figure 2. An ultrasound image of a cat’s kidney with a stone (yellow arrow). Ultrasound imaging is used to detect and target a stone.

cat calcium stone
Figure 3. (Left) A 3-mm natural feline calcium stone that was exposed to BWL and broke into several small fragments after treatment.

We are now preparing to perform veterinary clinical testing. Once its benefit is demonstrated, this technology could be made available as a safer and less invasive alternative to treat obstructing stones in cats. This work supported by NIDDK P01DK043881 and the EveryCat Health Foundation.

1aBAb1 – Acoustic intra-body communication using semi-guided waves through human body tissues

John O. Gerguis – jgerguis@purdue.edu
Mayukh Nath – nathm@purdue.edu
Shreyas Sen – shreyas@purdue.edu
Purdue University
516 Northwestern Ave
West Lafayette, IN, USA 47906

Popular version of 1aBAb1 – Ultrasonic intra-body communication using semi-guided waves through human body tissues
Presented Monday morning, November 29, 2021
181st  ASA Meeting in Seattle, Washington
Read the article in Proceedings of Meetings on Acoustics

The considerable attention that the Internet of Things (IOT) received in the recent years, has led to the development of low-cost and miniaturized devices. One of the fields that had a chance to benefit from this development is the Body Area Network (BAN), which is a network across the human body used to connect wearable and implantable devices.

Traditionally, Radio Frequency signals are used for the communication between devices across the BAN, which suffer from high losses and lack of security. Recently, electro-quasistatic human body communication, that uses the body as a wire, has emerged as an alternative – enabling low-power communication, and ultra-low leakage from human body (Das et al., 2019).

Acoustic waves have a better ability than Radio Frequency waves to propagate through water-dominant media, like the human body, besides being safe and physically secured in the body. Hence, ultrasounds present a promising alternative for the communication between wearable and/or implantable devices across the BAN.

In this work, a theoretical study was presented to explore the possibility of using ultrasounds for the communication between devices attached on the body. The ultrasound waves are confined inside the human tissues (muscle, fat and skin), thus a secure communication can be achieved, making it difficult for eavesdroppers to snoop the transmitted signal. (see Figure 1).

communication

Figure 1 “Intrabody communication between wearable devices through ultrasonic waves”

The confinement is achieved by avoiding the bone, a highly-attenuative tissue (has an attenuation of almost an order of magnitude higher than the other main tissues of the body), by having a total internal reflection on the bone/muscle interface through oblique incidence of ultrasounds on that interface. From the other side, the high acoustic impedance mismatch between the air and the skin, the outer layer of the human body, allows high reflection of the signal at the skin/air interface (~99.9%), thus confining most of the signal inside the body. By using directional acoustic wave propagation through the body and using total internal reflection, besides avoiding the bone, non-line-of-sight communication can be achieved as well between wearable devices with longer separations. This communication mechanism might be suitable in regions with thick bone (e.g. the leg).

Simulations are performed at an acoustic frequency of 100 kHz on a simplified cylindrical-shaped human body model, consisting of concentric layers of the four main tissues that form the human body: bone, muscle, fat and skin.

Figure 2. Total internal reflection of the acoustic waves on the bone.

Total internal reflection on the bone is shown in Figure 2 , where a transmitter is placed in location A and the receiver should be placed in location B. Figure 3(a) shows a ray tracing for the transmitted acoustic wave from the transmitter to the receiver, while Figure 3(b) shows the power density distribution at the receiver site. A communication between wearable devices across a distance of around 1m is shown to be possible with losses < 50 dB and with leakage signal which is >20 dB below the received signal, hence making the communication secure.

Figure 3(a). Ray tracing for the transmitted acoustic waves from the transmitter to the receiver.

 Figure 3(b). Power density distribution at the receiver site.

1aBAb – Detecting liver cracks using ultrasonic shear wave imaging

Jingfei Liu – jingfei.liu@ttu.edu
Texas Tech University
2500 Broadway
Lubbock, TX 79409

Popular version of 1aBAb – An ex vivo investigation of ultrasonic shear wave imaging for detecting liver cracks
Presented Monday morning, November 29, 2021
181st ASA Meeting
Click here to read the abstract

Liver crack is a type of liver trauma, in which a capsular tear of different geometries occurs due to external impacts, and it is a common physical damage in traffic accidents, combating sports, and other accidents. Since liver crack is an important source of morbidity and mortality in emergency medicine, a timely and accurate detection of the crack location and geometry is highly demanded. In current emergency care, ultrasonography, although has a low accuracy, is mostly used for initial examination of liver trauma due to its immediate availability, high mobility, and nonionizing nature. After the initial screening using ultrasonography, a more accurate diagnosis is normally achieved by X-ray computer tomography (CT). Although CT can provide more details of the liver damage, it is not easy to access because patients must be transport to CT facilities, and it is even risky for the patients like newborns whose condition is unstable. To develop a diagnostic technique which both has easy access and can provide accurate diagnosis, ultrasonic shear wave imaging was proposed in this study as a better option.

In this technique, shear wave, a different type of ultrasonic wave from the ultrasonic wave (longitudinal wave) used in typical ultrasonography, is first generated at the patients’ liver, and then tracked during its propagation. Because shear wave cannot propagate in blood, there will be strong reflection or diffraction at the crack locations, which ultrasonography cannot identify (because longitudinal wave can go through blood and no strong reflection is available). Thus, the location and severeness of targeted liver crack can possibly be detected.

In this study, the feasibility and effectiveness of this method was investigated in an ex vivo scenario. A porcine liver with cracks of different geometries was tested. Shear waves were generated using acoustic radiation force impulse and recorded using ultrafast ultrasound imaging. To find the best way to display the cracks, different methods of signal processing based on time-of-flight, shear wave modulus, and accumulated shear wave path were applied to the shear wave displacement extracted. The results show that shear wave imaging is a more sensitive method than the conventional ultrasonography in detecting liver cracks.

Blood Bubbles Reveal Oxygen Levels

Blood Bubbles Reveal Oxygen Levels

Acoustic tools detect vibrating microbubbles, act as oxygen sensors

Media Contact:
Larry Frum
AIP Media
301-209-3090
media@aip.org

SEATTLE, November 29, 2021 – Blood carries vital oxygen through our circulation system to muscles and organs. Acoustic tools can create small bubbles in our blood, capable of changing in response to oxygen and signifying oxygen levels.

During the 181st Meeting of the Acoustical Society of America, which will be held Nov. 29 to Dec. 3, Shashank Sirsi, from the University of Texas at Dallas, will discuss how circulating microbubbles can be used to measure oxygen levels. The talk, “Hemoglobin Microbubbles for In Vivo Blood Oxygen Level Dependent Imaging: Boldly Moving Beyond MRI,” will take place Monday, Nov. 29, at 11:25 a.m. Eastern U.S.

Microbubbles are smaller than one hundredth of a millimeter in diameter and can be made by emulsifying lipids or proteins with a gas. The gas filling of microbubbles causes them to oscillate and vibrate when ultrasound is applied, scattering energy and generating an acoustic response that can be detected by a clinical ultrasound scanner. They are routinely used in medical imaging to provide greater contrast in tissue.

Hemoglobin, the protein that gives red blood cells their signature color, will form a stable shell around microbubbles. It then continues to carry out its typical role of binding and releasing oxygen in blood.

Sirsi and his team developed microbubbles to acoustically detect blood oxygen levels, since the microbubble shells are altered by structural hemoglobin changes in response to oxygen. The hemoglobin shell is continually responsive to oxygen after surrounding the bubble and has been optimized to perform in living organisms’ circulation.

“When oxygen binds to hemoglobin, there are structural changes in the protein that change the mechanical properties,” said Sirsi. “The mechanical properties of the shell dictate the acoustic response of a bubble, so our hypothesis was that different acoustic responses would be seen as the shell gets stiffer or more elastic.”

Preliminary results show a strong correlation between oxygen concentration and the acoustic bubble response, highlighting the potential use of microbubbles as oxygen sensors. This capability would have many benefits for medicine and imaging, including evaluating oxygen-deprived regions of tumors and in the brain.

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