4pBA1 – Kidney stone pushing and trapping using focused ultrasound beams of different structure

Oleg Sapozhnikov – olegs@apl.washington.edu
Mike Bailey – bailey@apl.washigton.edu
Adam Maxwell – amax38@uw.edu

Physics Faculty
Moscow State Univerity
Moscow
RUSSIAN FEDERATION

Center for Industrial and Medical Ultrasound
Applied Physics Laboratory
University of Washington
Seattle, WashingtonUNITED STATES

Popular version of paper 4pBA1, “Kidney stone pushing and trapping using focused ultrasound beams of different structure.”
Presented Thursday afternoon, December 1, 2016 at 1:00pmHAST.
172nd ASA Meeting, Honolulu

Urinary stones (such as kidney or bladder stones) are an important health care problem. One in 11 Americans now has urinary stone disease (USD), and the prevalence is increasing. According to a 2012 report from the National Institute of Diabetes and Kidney and Digestive Diseases (Urological Diseases in America), the direct medical cost of USD in the United States is $10 billion annually, making it the most expensive urologic condition.

Our lab is working to develop more effective and more efficient ways to treat stones. Existing treatments such as shock wave lithotripsy or ureteroscopy are minimally invasive, but can leave behind stone fragments that remain in the kidney and potentially regrow into larger stones over time. We have successfully developed and demonstrated the use of ultrasound to noninvasively move stones in the kidney of human subjects. This technology, called ultrasonic propulsion (UP), uses ultrasound to apply a directional force to the stone, propelling it in a direction away from the sonic source, or transducer. Some stones need to be moved towards the ureteropelvic junction (the exit from the kidney that allows stones to pass through the ureter to the bladder) to aid their passage. In other cases, this technology may be useful to relieve an obstruction caused by a stone that may just need a nudge or a rotation to pass, or at least to allow urine to flow and decompress the kidney.

While UP is able to help stones pass, it is limited in how the stones can be manipulated by an ultrasound transducer in contact with the skin from outside the body. Some applications require the stone to be moved sideways or towards the transducer rather than away from it.

To achieve more versatile manipulation of stones, we are developing a new strategy to effectively trap a stone in an ultrasound beam. Acoustic trapping has been explored by several other researchers, particularly for trapping and manipulating cells, bubbles, droplets, and particles much smaller than length of the sound wave. Different configurations have been used to trap particles in standing waves and focused fields. By trapping the stone in an ultrasound beam, we can then move the transducer or electronically steer the beam to move the stone with it.

sapozhnikov1 Kidney stone

Figure 1. The cross section at the focus for the ultrasound pressure of a vortex beam. The pressure magnitude (left) has a donut-shape distribution, whereas the phase (right) has a spiral-shape structure. A stone can be trapped at the center of the ring.

In this work, we accomplished trapping through the use of vortex beams. Typical focused beams create a single region of high ultrasound pressure, producing radiation force away from the transducer. Vortex beams, on the other hand, are focused beams that create a tube-shaped intensity pattern with a spiraling wave front (Fig. 1). The ultrasound pressure in the middle is very low, while the pressure around the center is high. The result is that there is a component of the ultrasound radiation force pushing the stone towards the center and trapping it in the middle of the beam. In addition to trapping, such a beam can apply a torque to the stone and can rotate it.

To test this idea, we simulated the radiation force on spheres of different materials (including stones) to determine how each would respond in a vortex beam. An example is shown in Fig 2. A lateral-axial cross section of the beam is displayed, with a spherical stone off-center in the tube-shaped beam. The red arrow shows that the force on the sphere is away from the center because the stone is outside of the vortex. Once the center of the stone crosses the peak, the force is directed inward. Usually, there is also some force away from the transducer still, but the object can be trapped against a surface.

Figure 2. The simulated tubular field such as occurs in a vortex beam and its force on a stone. In this simulation the transducer is on the left and the ultrasound propagates to the right. The arrow indicates the force which depends on the position of the stone.

We also built transducers and electrically excited them to generate the vortex in experiments. At first, we used the vortex to trap, rotate, and drag an object on the water surface (Fig. 3). By changing the charge of the vortex beam (the rate of spiraling generated by the transducer), we controlled the diameter of the vortex beam, as well as the direction and speed at which the objects rotated. We also tested manipulation of objects placed deep in a water tank. Glass or plastic beads and kidney stones placed on a platform of tissue-mimicking material. By physically shifting the transducer, we were able to move these objects a specified distance and direction along the platform (Fig 4). These results are best seen in videos at apl.uw.edu/pushingstones.

Figure 3. A small object trapped in the center of a vortex beam on the water surface. The ring-shaped impression due to radiation force on the surface can be seen. The phase difference between each sector element of the transducer affects the diameter of the beam and the spin rate. The 2 mm plastic object floating on the surface is made to rotate by the vortex beam.

Figure 4. A focused vortex beam transducer in water (shown on the top) traps one of the styrofoam beads (shown in the bottom) and translates it in lateral direction.

We have since worked on developing vortex beams with a 256-element focused array transducer. Our complex array can electronically move the beam and drag the stone without physically moving the transducer. In a highly focused transducer, such as our array, sound can even be focused beyond the stone to generate an axial high pressure spot to help trap a stone axially or even pull the stone toward the transducer.

There are several ways in which this technology might be useful for kidney stones. In some cases, it might be employed in gathering small particles together and moving them collectively, holding a larger stone in place for fragmentation techniques such as lithotripsy, sweeping a stone when the anatomy inhibits direct radiation force away from the transducer, or, as addressed here dragging or pulling a stone. In the future, we expect to continue developing phased array technology to more controllably manipulate stones. We are also working to develop and validate new beam profiles, and electronic controls to remotely gather the stone and move it to a new location. We expect that this sort of tractor beam could also have applications in manufacturing, such as ever shrinking electronics, and even in space.

This work was supported by RBBR 14-02- 00426, NIH NIDDK DK43881 and DK104854, and NSBRI through NASA NCC 9-58.

References

  1. O.A. Sapozhnikov and M.R. Bailey. Radiation force of an arbitrary acoustic beam on an elastic sphere in a fluid. – J. Acoust. Soc. Am., 2013, v. 133, no. 2, pp. 661-676.
  2. A.V. Nikolaeva, S.A. Tsysar, and O.A. Sapozhnikov. Measuring the radiation force of megahertz ultrasound acting on a solid spherical scatterer. – Acoustical Physics, 2016, v. 62, no. 1, pp. 38-45.
  3. J.D. Harper, B.W. Cunitz, B. Dunmire, F.C. Lee, M.D. Sorensen, R.S. Hsi, J. Thiel, H. Wessells, J.E. Lingeman, and M.R. Bailey. First in human clinical trial of ultrasonic propulsion of kidney stones. – J. Urology, 2016, v. 195, no. 4 (Part 1), pp. 956–964.

3aBA1 – Ultrasound-Mediated Drug Targeting to Tumors: Revision of Paradigms Through Intravital Imaging

Natalya Rapoport – natasha.rapoport@utah.edu
Department of Bioengineering
University of Utah
36 S. Wasatch Dr., Room 3100
Salt Lake City, Utah 84112
USA

Popular version of paper 3aBA1, “Ultrasound-mediated drug targeting to tumors: Revision of paradigms through intravital imaging”
Presented Wednesday morning, May 25, 2016, 8:15 AM in Salon H
171st ASA Meeting, Salt Lake City

More than a century ago, Nobel Prize laureate Paul Ehrlich formulated the idea of a “magic bullet”. This is a virtual drug that hits its target while bypassing healthy tissues. No field of medicine could benefit more from the development of a “magic bullet” than cancer chemotherapy, which is complicated by severe side effects. For decades, the prospects of developing “magic bullets” remained elusive. During the last decade, progress in nanomedicine has enabled tumor-targeted delivery of anticancer drugs via their encapsulation in tiny carriers called nanoparticles. Nanoparticle tumor targeting is based on the “Achilles’ heels” of cancerous tumors – their poorly organized and leaky microvasculature. Due to their size, nanoparticles are not capable to penetrate through a tight healthy tissue vasculature. In contrast, nanoparticles penetrate through a leaky tumor microvasculature thus providing for localized accumulation in tumor tissue.  After tumor accumulation of drug-loaded nanoparticles, a drug should be released from the carrier to allow penetration into a site of action (usually located in a cell cytoplasm or nucleus). A local release of an encapsulated drug may be triggered by tumor-directed ultrasound; application of ultrasound has additional benefits: ultrasound enhances nanoparticle penetration through blood vessel walls (extravasation) as well as drug uptake (internalization) by tumor cells.

For decades, ultrasound has been used only as an imaging modality; the development of microbubbles as ultrasound contrast agents in early 2000s has revolutionized imaging. Recently, microbubbles have attracted attention as drug carriers and enhancers of drug and gene delivery. Microbubbles could have been ideal carriers for the ultrasound-mediated delivery of anticancer drugs.  Unfortunately, their micron-scale size does not allow effective extravasation from the tumor microvasculature into tumor tissue. In Dr. Rapoport’s lab, this problem has been solved by the development of nanoscale microbubble precursors, namely drug-loaded nanodroplets that converted into microbubbles under the action of ultrasound[1-6]. Nanodroplets comprised a liquid core formed by a perfluorocarbon compound and a two-layered drug-containing polymeric shell (Figure 1). An aqueous dispersion of nanodroplets is called nanoemulsion.

Rapoport 1 - Ultrasound-Mediated Drug Targeting

Figure 1. Schematic representation of a drug-loaded nanodroplet

A suggested mechanism of therapeutic action of drug-loaded perfluorocarbon nanoemulsions is discussed below [3, 5, 6]. A nanoscale size of droplets (ca. 250 nm) provides for their extravasation into a tumor tissue while bypassing normal tissues, which is a basis of tumor targeting. Upon nanodroplet tumor accumulation, tumor-directed ultrasound triggers nanodroplet conversion into microbubbles, which in turn triggers release of a nanodroplet-encapsulated drug. This is because in the process of the droplet-to-bubble conversion, particle volume increases about a hundred-fold, with a related decrease of a shell thickness. Microbubbles oscillate in the ultrasound field, resulting in a drug “ripping” off a thin microbubble shell (Figure 2). In addition, oscillating microbubbles enhance internalization of released drug by tumor cells.

Rapoport 2 - Ultrasound-Mediated Drug Targeting

Figure 2. Schematic representation of the mechanism of drug release from perfluorocarbon nanodroplets triggered by ultrasound-induced droplet-to-bubble conversion; PFC – perfluorocarbon

This tumor treatment modality has been tested in mice bearing breast, ovarian, or pancreatic cancerous tumors and has been proved very effective. Dramatic tumor regression and sometimes complete resolution was observed when optimal nanodroplet composition and ultrasound parameters were applied.

3A.Rapoport 3A 3B.Rapoport 3B 3C.Rapoport 3C

(Figure 3. A – Photographs of a mouse bearing a subcutaneously grown breast cancer tumor xenograft treated by four systemic injections of the nanodroplet-encapsulated anticancer drug paclitaxel (PTX) at a dose of 40 mg/kg as PTX. B – Photographs of a mouse bearing two ovarian carcinoma tumors (a) – immediately before and (b) – three weeks after the end of treatment; mouse was treated by four systemic injections of the nanodroplet-encapsulated PTX at a dose of 20 mg/kg as PTX; only the right tumor was sonicated. C – Photographs (a, c) and fluorescence images (b, d) of a mouse bearing fluorescent pancreatic tumor taken before (a, b) and three weeks after the one-time treatment with PTX-loaded nanodroplets at a dose of 40 mg/kg as PTX (c,d). The tumor was completely resolved and never recurred)[3, 4, 6].

In the current presentation, the proposed mechanism of a therapeutic action of drug-loaded, ultrasound-activated perfluorocarbon nanoemulsions has been tested using intravital laser fluorescence microscopy performed in collaboration with Dr. Brian O’Neill (then with Houston Methodist Research Institute, Houston, Texas) [2]. Fluorescently labeled nanocarrier particles (or a fluorescently labeled drug) were systemically injected though the tail vein to anesthetized live mice bearing subcutaneously grown pancreatic tumors. Nanocarrier and drug arrival and extravasation in the region of interest (i.e. normal or tumor tissue) were quantitatively monitored. Various drug nanocarriers in the following size hierarchy were tested: individual polymeric molecules; tiny micelles formed by a self-assembly of these molecules; nanodroplets formed from micelles. The results obtained confirmed the mechanism discussed above.

  • As expected, dramatic differences in the extravasation rates of nanoparticles were observed.
  • The extravsation of individual polymer molecules was extremely fast even in the normal (thigh muscle) tissue; In contrast, the extravasation of nanodroplets into the normal tissue was very slow. (Figure 4. A – Bright field image of the adipose and thigh muscle tissue. B,C – extravasation of individual molecules (B – 0 min; C – 10 min after injection); vasculature lost fluorescence while tissue fluorescence increased. D,E – extravasation of nanodroplets; blood vessel fluorescence was retained for an hour of observation (D – 30 min; E – 60 min after injection).
  • Nanodroplet extravasation into the tumor tissue was substantially faster than that into the normal tissue thus providing for effective nanodroplet tumor targeting.
  • Tumor-directed ultrasound significantly enhanced extravasation and tumor accumulation of both, micelles and nanodroplets (Figure 5). Also, pay attention to a very irregular tumor microvasculature, to be compared with that of a normal tissue shown in Figure 4.
  • The ultrasound effect on nanodroplets was 3-fold stronger than that on micelles thus making nanodroplets a better drug carriers for ultrasound-mediated drug delivery.
  • On a negative side, some premature drug release into the circulation that preceded tumor accumulation was observed. This proposes directions for a further improvement of nanoemulsion formulations.

Rapoport 5 - Ultrasound-Mediated Drug Targeting

Figure 5. Effect of ultrasound on the extravasation of Fluorescence of blood vessels dropped while that of the tumor tissue increased after ultrasound

3aBA – Using Ultrasound to Deliver Nanomedicine for the Treatment of Parkinson’s Disease

Richard J. Price – rprice@virginia.edu
University of Virginia
Box 800759, Health System
Charlottesville, VA 22908

Popular version of paper 3aBA
Presented Wednesday morning, May 25, 2016
171st ASA Meeting, Salt Lake City

Parkinson’s disease is characterized by the degeneration of nerve cells in the brain, often leading to poor balance, difficulties with walking, muscle pain and rigidity, tremors and involuntary movements, dementia, and memory loss. Fortunately, new gene therapy approaches for treating the root cause of the problem (i.e. neural cell degeneration) are beginning to show some pre-clinical success. These approaches involve introducing genes for neurotrophic factors [i.e. glial derived neurotrophic factor (GDNF)] into well-defined regions of the brain that are affected by neurodegeneration. Once the gene is introduced into the neural cells, the hope is that they will begin to manufacture the neurotrophic protein which, in turn, will halt neural degeneration. However, as currently implemented, there are significant weaknesses to such approaches. Foremost, the genes must be delivered by direct injection through a needle and/or infection-prone indwelling catheters. In addition to being highly invasive procedures, these direct injection approaches are unlikely to yield a homogeneous distribution of the gene in the target region of the brain. Indeed, due to both the fact that human gene therapy is in its genesis and that these current gene delivery procedures are highly invasive, only patients with very advanced disease will be considered candidates for treatment at first. This is unfortunate because, ideally, patients should be treated before significant degeneration occurs. Thus, the ultimate goal is to develop a new and minimally-invasive gene delivery approach for Parkinson’s that would incur minimal risk to the patient and therefore be safe enough to apply to healthy “early-stage” patients who are just beginning to exhibit symptoms.

Our proposed approach entails delivering non-viral neurotrophic gene-bearing nanocarriers to specific regions of the brain following their intravenous injection into the bloodstream. To achieve this, two physical barriers to gene delivery must be overcome. The first is the barrier offered by brain tissue itself, the so-called brain-tissue barrier (BTB). Our collaborators at Johns Hopkins University have developed a new technology that allows nanoparticles to diffuse easily through the BTB. These so-called “brain-penetrating nanoparticles” exhibit uniform, long-lasting, and effective delivery. The second barrier to delivery is the blood-brain barrier (BBB), the essentially impenetrable membrane created by brain capillaries that separates the bloodstream from brain tissue. The Price lab at the University of Virginia has been studying how the BBB may be opened in a site selective manner for targeted drug and gene delivery. In essence, they have shown that applying focused ultrasound energy to the brain after the injection of micron-sized gas bubbles (FDA approved for other applications) can open the BBB (Figure 1). Of particular importance to this project, the Price group has demonstrated that opening the BBB with this targeted technology permits the delivery of brain-penetrating nanoparticles (fabricated in the Hanes lab) from the bloodstream to the tissue. The nanoparticles are transported by diffusion and convection to the brain and distribute evenly throughout, yielding homogeneous delivery without an invasive transcranial injection.

Price Figure 1 - Parkinson’s Disease

Figure 1. Transcranial focused ultrasound achieves non-invasive, safe, repeated and targeted blood-brain barrier disruption, leading to improved drug or gene delivery.

Advancing this concept to the clinic as a treatment for Parkinson’s disease will require testing the efficacy of the approach in a small animal model of neurodegeneration. Here, we first delivered non-viral reporter gene nanoparticles to rat brain using focused ultrasound, resulting in robust dose-dependent gene expression, only in the region exposed to ultrasound, through day 28. We also measured a transfection efficiency (i.e. the percentage of cells expressing the delivered gene) at > 40%. Toxicity was not evident. We then tested whether the approach had therapeutic potential for treating Parkinson’s disease by delivering neurotrophic (GDNF) gene nanoparticles to the striatum of Parkinson’s rats. MR images of BBB opening with focused ultrasound in the striatum are shown in Figure 2. For treated rats, motor impairment tests (apomorphine-induced rotation and cylinder) revealed significant improvement and dopaminergic neuron density was fully restored in key brain structures (i.e. striatum and substantia nigra pars compacta). We conclude that image-guided nanoparticle delivery with focused ultrasound is a safe and non-invasive strategy for brain transfection that has potential to be translated into a non-invasive clinical treatment for Parkinson’s disease.

Price Figure 2

Figure 2. Left: MR image showing structure of the striatum (outlined in yellow), which is the brain region targeted for treatment. Right: MR image of the striatum after treatment with focused ultrasound. The 4 bright spots show where the BBB has been opened in the striatum, allowing for the delivery of gene nanoparticles.

2aBAa7 – Ultrasonic “Soft Touch” for Breast Cancer Diagnosis

Mahdi Bayat – bayat.mahdi@mayo.edu
Alireza Nabavizadeh- nabavizadehrafsanjani.alireza@mayo.edu
Viksit Kumar- kumar.viksit@mayo.edu
Adriana Gregory- gregory.adriana@mayo.edu
Azra Aliza- alizad.azra@mayo.edu
Mostafa Fatemi- Fatemi.mostafa@mayo.edu
Mayo Clinic College of Medicine
200 First St SW
Rochester, MN 55905

Michael Insana- mfi@illinois.edu
University of Illinois at Urbana-Champaign
Department of Bioengineering
1270 DCL, MC-278
1304 Springfield Avenue
Urbana, IL 61801

Popular version of paper 2aBAa7, “Differentiation of breast lesions based on viscoelasticity response at sub-Hertz frequencies”
Presented Tuesday Morning, May 24, 2016, 9:30 AM, Snowbird/Brighton room
171st ASA Meeting, Salt Lake City

Breast cancer remains the first cause of death among American women under the age of 60. Although modern imaging technologies, such as enhanced mammography (tomosynthesis), MRI and ultrasound, can visualize a suspicious mass in breast, it often remains unclear whether the detected mass is cancerous or non-cancerous until a biopsy is performed.

Despite high sensitivity for detecting lesions, no imaging modality alone has yet been able to determine the type of all abnormalities with high confidence. For this reason most patients with suspicious masses, even those with very small likelihood of a cancer, opt in to undergo a costly and painful biopsy.

It is long believed that cancerous tumors grow in the form of stiff masses that, if found to be superficial enough, can be identified by palpation. The feeling of hardness under palpation is directly related to the tissue’s tendency to deform upon compression.  Elastography, which has emerged as a branch of ultrasound, aims at capturing tissue stiffness by relating the amount of tissue deformation under a compression to its stiffness. While this technique has shown promising results in identifying some types of breast lesions, the diversity of breast cancer types leaves doubt whether stiffness alone is the best discriminator for diagnostic purposes.

Studies have shown that tissues subjected to a sudden external force do not deform instantly, rather they deform gradually over a period of time. Tissue deformation rate reveals another important aspect of its mechanical property known as viscoelasticity. This is the main material feature that, for example, makes a piece of memory foam to feel differently from a block of rubber under the touch. Similar material feature can be used to explore mechanical properties of different types of tissue. In breast masses, studies have shown that biological pathways leading to different breast masses are quite different. While in benign lesions an increase in a protein-based component can potentially increase its viscosity, hence a slower deformation rate compared to normal tissue, the opposite trend occurs in malignant tumors.

In this study, we report on using an ultrasound technique that enables capturing the deformation rate in breast tissue. We studied 43 breast masses in 42 patients and observed that a factor based on the deformation rate was significantly different in benign and malignant lesions (Fig. 1).

The results of this study promise a new imaging biomarker for diagnosis of the breast masses. If such technique proves to be of high accuracy in a large pool of patients, then this technology can be integrated into breast examination procedures to improve the accuracy of diagnosis, reduce unnecessary biopsies, and help detecting cancerous tumors early on

Figure 1 breast cancer

Figure1- Distribution of relative deformation rates for malignant and benign breast lesions. A significantly different relative deformation rates can be observed in the two groups, thus allowing differentiation of such lesions.

2aBAa5 – Sound Waves Helps Assess Bone Condition

Max Denis – denis.max@mayo.edu
507-266-7449

Leighton Wan – wan.leighton@mayo.edu
Matthew Cheong – cheong.matthew@mayo.edu
Mostafa Fatemi – fatemi.mostafa@mayo.edu
Azra Alizad – alizad.azra@mayo.edu
507-254-5970

Mayo Clinic College of Medicine
200 1st St SW
Rochester, MN 55905

Popular version of paper 2aBAa5, “Bone demineralization assessment using acoustic radiation force”
Presented Tuesday morning, May 24, 2016, 9:00 AM in Snowbird/Brighton room
171st ASA Meeting, Salt Lake City, Utah

The assessment of the human skeletal health condition is of great importance ranging from newborn infants to the elderly. Annually, approximately fifty percent of the 550,000 premature newborn infants in the United States suffer from bone metabolism related disorders such as osteopenia, which affect the bone development process into childhood. As we age through adulthood, reductions in our bone mass increases due an unbalance activity in the bone reformation process leading to bone diseases such as osteoporosis; putting a person at risk for fractures in the neck, hip and forearm areas.

Currently bone assessment tools include dual-energy X-ray absorptiometry (DEXA), and quantitative ultrasound (QUS). DEXA is the leading clinical bone quality assessment tool, detecting small changes in bone mineral content and density. However, DEXA uses ionizing radiation for imaging thus exposing patients to very low radiation doses. This can be problematic for frequent clinical visits to monitor the efficacy of prescribed medications and therapies.

QUS has been sought as a nonionizing and noninvasive alternative to DEXA. QUS utilizes measurements of ultrasonic waves between a transmitting and a receiving transducer aligned in parallel along bone surface. Speed of sound (SOS) measurements of the received ultrasonic signal is used to characterize the bone material properties. The determination of the SOS parameter is susceptible to the amount of soft tissue between the skin surface and the bone. Thus, we propose utilizing a high intensity ultrasonic wave known as a “push beam” to exert a force on the bone surface thereby generating vibrations. This will minimize the effects of the soft tissue. The radiate sound wave due to these vibrations are captured and used to analyze the bone mechanical properties.

This work demonstrates the feasibility of evaluating bone mechanical properties from sound waves due to bone vibrations. Under an approved protocol by the Mayo Clinic Institutional Review Board (IRB), human volunteers were recruited to undergo our noninvasive bone assessment technique. Our cohort consisted of clinically confirmed osteopenia and osteoporosis patients, as well as normal volunteers without a history of bone fractures. An ultrasound probe and hydrophone were placed along the volunteers’ tibia bone (Figure 1a). A B-mode ultrasound was used to guide the placement of our push beam focal point onto the bone surface underneath the skin layer (Figure 1b). The SOS was obtained from the measurements.

Denis1 bone

Figure 1. (a) Probe and hydrophone alignment along the tibia bone. (b) Diagram of an image-guided push beam focal point excitation on the bone surface.

In total 14 volunteers were recruited in our ongoing study. A boxplot comparison of SOS between normal and bone diseased (osteopenia and osteoporotic) volunteers in Figure 2, shows that typically sound travels faster in healthy bones than osteoporotic and osteopenia bones with SOS median values (red line) of 3733 m/s and 2566 m/s, respectively. Hence, our technique may be useful as a noninvasive method for monitoring the skeletal health status of the premature and aging population.

Denis2 bone

Figure 2. Normal and bone diseased volunteers sound of speed comparisons.

This ongoing project is being done under an approved protocol by Mayo Institutional Review Board.

3pBA5 – Using Acoustic Levitation to Understand, Diagnose, and Treat Cancer and Other Diseases

Brian D. Patchett – brian.d.patchett@gmail.com
Natalie C. Sullivan – nhillsullivan@gmail.com
Timothy E. Doyle – Timothy.Doyle@uvu.edu

Department of Physics
Utah Valley University
800 West University Parkway, MS 179
Orem, Utah 84058

Popular version of paper 3pBA5, “Acoustic Levitation Device for Probing Biological Cells With High-Frequency Ultrasound”
Presented Wednesday afternoon, November 4, 2015
170th ASA Meeting, Jacksonville

Imagine a new medical advancement that would allow scientists to measure the physical characteristics of diseased cells involved in cancer, Alzheimer’s, and autoimmune diseases. Through the use of high-frequency ultrasonic waves, such an advancement will allow scientists to test the normal healthy range of virtually any cell type for density and stiffness, providing new capabilities for analyzing healthy cell development as well as insight into the changes that occur as diseases develop and the cells’ characteristics begin to change.

Prior research methods of probing cells with ultrasound have relied upon growing the cells on the bottom of a Petri dish, which distorts not only the cells’ shape and structure, butlso interfere with the ultrasonic signals. A new method was therefore needed to probe the cells without disturbing their natural form, and to “clean up” the signals received by the ultrasound device. Research presented at the 2015 ASA meeting in Jacksonville Florida will show that the use of acoustic levitation is effective in providing the ideal conditions for probing the cells.

Acoustic levitation is a phenomenon whereby pressure differences of stationary sound waves can be used to suspend small objects in gases or fluids such as air or water. We are currently exploring a new frontier in acoustic levitation of cellular structures in a fluid medium by perfecting a method by which we can manipulate the shape and frequency of sound waves inside of special containers. By manipulating these sound waves in just the right fashion it is possible to isolate a layer of cells in a fluid such as water, which can then be probed with an ultrasound device. The cells are then in a more natural form and environment, and the interference from the floor of the Petri dish is no longer a hindrance.

This method has proven effective in the laboratory with buoyancy neutral beads that are roughly the same size and shape as human blood cells, and a study is currently underway to test the effectiveness of this method with biological samples. If effective, this will give researchers new experimental methods by which to study cellular processes, thus leading to a better understanding of the development of certain diseases in the human body.