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.

4aEA2 – How soon can you use your new concrete driveway?

Jinying Zhu: jyzhu@unl.edu
Department of Civil Engineering
University of Nebraska-Lincoln
1110 S 67th St., Omaha, NE 68182, USA

Popular version of paper 4aEA2, “Monitoring hardening of concrete using ultrasonic guided waves” Presented Thursday morning, Nov. 5, 2015, 8:50 AM, ORLANDO room,
170th ASA Meeting, Jacksonville, FL

Concrete is the most commonly used construction material in the world. The performance of concrete structures is largely determined by properties of fresh concrete at early ages. Concrete gains strength through a chemical reaction between water and cement (hydration), which gradually change a fluid fresh concrete mix to a rigid and hard solid. The process is called setting and hardening.  It is important to measure the setting times, because you may not have enough time to mix and place concrete if the setting time is too early, while too late setting will cause delay in strength gain.  The setting and hardening process is affected by many parameters, including water and cement ratio, temperature, and chemical admixtures.  The standard method to test setting time is to measure penetration resistance of fresh concrete samples in laboratory, which may not represent the real condition in field.

Zhu1 - concrete

Figure. 1 Principle of ultrasonic guided wave test.

Ultrasonic waves have been proposed to monitor the setting and hardening process of concrete by measuring wave velocity change. When concrete becomes hard, the stiffness increases, and the ultrasonic velocity also increases. The authors found there is a clear relationship between the shear wave velocity and the traditional penetration resistance. However, most ultrasonic tests measure a small volume of concrete sample in laboratory, and they are not suitable for field application. In this paper, the authors proposed an ultrasonic guided wave test method. Steel reinforcements (rebars) are used in most concrete structures. When ultrasonic guided waves propagate within rebar, they leak energy to surrounding concrete, and the energy leakage rate is proportion to the stiffness of concrete.  Ultrasonic waves can be introduced into rebars from one end and the echo signal will be received at the same end using the same ultrasonic sensor.  This test method has a simple test setup, and is able to monitor the concrete hardening process continuously.

zhu2 - concrete Zhu3 - concrete
Figure. 2 Ultrasonic echo signals measured in an embedded rebar for concrete age of 2~6 hours. Figure. 3 Guided wave attenuation rate in a rebar embedded in different cement pastes.

Figure 2 shows guided wave echo signals measured on a 19mm diameter rebar embedded in concrete. It is clear that the signal amplitude decreases with the age of concrete (2 ~ 6 hours). The attenuation can be plotted vs. age for different cement/concrete mixes. Figure 3 shows the attenuation curves for 3 cement paste mixes. It is known that a cement mix with larger water cement ratio (w/c) will have slower strength gain, which agrees with the ultrasonic guided wave test, where the w/c=0.5 mix has lower attenuation rate.  When there is a void around the rebar, energy leakage will be less than the case without a void, which is also confirmed by the test result in Figure 3.

Summary: This study presents experimental results using ultrasonic guided waves to monitor concrete setting and hardening process. It shows the guided wave leakage attenuation is proportional to the stiffness change of fresh concrete. Therefore the leakage rate can be used to monitor the concrete strength gain at early ages. This study may have broader applications in other disciplines to measure mechanical property of material using guided wave.

3aBA5 – Fabricating Blood Vessels with Ultrasound

Diane Dalecki, Ph.D.
Eric S. Comeau, M.S.
Denise C. Hocking, Ph.D.
Rochester Center for Biomedical Ultrasound
University of Rochester
Rochester, NY 14627

Popular version of paper 3aBA5, “Applications of acoustic radiation force for microvascular tissue engineering”
Presented Wednesday morning May 20, 9:25 AM, in room Kings 2
169th ASA Meeting, Pittsburgh

Tissue engineering is the field of science dedicated to fabricating artificial tissues and organs that can be made available for patients in need of organ transplantation or tissue reconstructive surgery. Tissue engineers have successfully fabricated relatively thin tissues, such as skin substitutes, that can receive nutrients and oxygen by simple diffusion. However, recreating larger and/or more complex tissues and organs will require developing methods to fabricate functional microvascular networks to bring nutrients to all areas of the tissue for survival.

In the laboratories of Diane Dalecki, Ph.D. and Denise C. Hocking, Ph.D., research is underway to develop new ultrasound technologies to control and enhance the fabrication of artificial tissues1. Ultrasound fields are sound fields at frequencies higher than humans can hear (i.e., > 20 kHz). Dalecki and Hocking have developed a technology that uses a particular type of ultrasound field, called an ultrasound standing wave field, as a tool to non-invasively engineer complex spatial patterns of cells2 and fabricate microvessel networks3,4 within artificial tissue constructs.

When a solution of collagen and cells is exposed to an ultrasound standing wave field, the forces associated with the field lead to the alignment of the cells into planar bands (Figure 1). The distance between the bands of cells is controlled by the ultrasound frequency, and the density of cells within each band is controlled by the intensity of the sound field. The collagen polymerizes into a solid gel during the ultrasound exposure, thereby maintaining the spatial organization of the cells after the ultrasound is turned off. More complex patterning can be achieved by use of more than one ultrasound transducer.

Dalecki-1-ASA

Figure 1. Acoustic-patterning of microparticles (dark bands) using an ultrasound standing wave field. Distance between planar bands is 750 µm. Scale bar = 100 μm

An exciting application of this technology involves the fabrication of microvascular networks within artificial tissue constructs. Specifically, acoustic-patterning of endothelial cells into planar bands within collagen hydrogels leads to the rapid development of microvessel networks throughout the entire volume of the hydrogel. Interestingly, the structure of the resultant microvessel network can be controlled by choice of the ultrasound exposure parameters. As shown in Figure 2, ultrasound standing wave fields can be employed to fabricate microvessel networks with different physiologically relevant morphologies, including capillary-like networks (left panel), aligned non-branching vessels (center panel) or aligned vessels with hierarchically branching microvessels. Ultrasound fields provide an ideal technology for microvascular engineering; the technology is rapid, noninvasive, can be broadly applied to many types of cells and hydrogels, and can be adapted to commercial fabrication processes.

Dalecki-2-ASA - Ultrasound-fabricated microvessel

Figure 2. Ultrasound-fabricated microvessel networks within collagen hydrogels. The ultrasound pressure amplitude used for initial patterning determines the final microvessel morphology, which can resemble torturous capillary-like networks (left panel), aligned non-branching vessels (center panel) or aligned vessels with hierarchically branching microvessels. Scale bars = 100 μm.

To learn more about this research, please view this informative video (https://www.youtube.com/watch?v=ZL-cx21SGn4).

References:

[1] Dalecki D, Hocking DC. Ultrasound technologies for biomaterials fabrication and imaging. Annals of Biomedical Engineering 43:747-761; 2015.

[2] Garvin KA, Hocking DC, Dalecki D. Controlling the spatial organization of cells and extracellular matrix proteins in engineered tissues using ultrasound standing wave fields. Ultrasound Med. Biol. 36:1919-1932; 2010.

[3] Garvin KA, Dalecki D, Hocking DC. Vascularization of three-dimensional collagen hydrogels using ultrasound standing wave fields. Ultrasound Med. Biol. 37:1853-1864; 2011.

[4] Garvin KA, Dalecki D, Youssefhussien M, Helguera M, Hocking DC. Spatial patterning of endothelial cells and vascular network formation using ultrasound standing wave fields. J. Acoust. Soc. Am. 134:1483-1490; 2013.

4pBA1 – Ultrasound Helps Detect Cancer Biomarkers

Tatiana Khokhlova – tdk7@uw.edu
George Schade – schade@uw.edu
Yak-Nam Wang – ynwang@uw.edu
Joo Ha Hwang – jooha@uw.edu
University of Washington
1013 NE 40th St
Seattle, WA 98105

John Chevillet – jchevill@systemsbiology.org
Institute for Systems Biology
401 Terry Ave N
Seattle, WA 98109

Maria Giraldez – mgiralde@med.umich.edu
Muneesh Tewari – mtewari@med.umich.edu
University of Michigan
109 Zina Pitcher Place 4029
Ann Arbor, MI 48109

Popular version of paper 4pBA1 High intensity focused ultrasound-induced bubbles stimulate the release of nucleic acid cancer biomarkers
Presented Thursday afternoon, October 30, 2014, at 1:30 pm
168th ASA Meeting, Indianapolis

The clinical evaluation of solid tumors typically includes needle biopsies, which can provide diagnostic (benign vs. cancer) and molecular information (targetable mutations, drug resistance, etc). This procedure has several diagnostic limitations, most notably, the potential to miss the mutations only millimeters away. In response to these limitations, the concept of “liquid biopsy” has emerged in recent years: the detection of nucleic acid cancer biomarkers, such as tumor-derived microRNAs (miRNAs) and circulating tumor DNA (ctDNA). These biomarkers have shown high diagnostic value and could guide the selection of appropriate targeted therapies. However, the abundance of these biomarker classes in the circulation is often too low to be detectable even with the most sensitive techniques because of their low levels of release from the tumor.

illustration1 - Cancer Biomarkers

Figure caption: Experimental setup and the basic concept of “ultrasound-aided liquid biopsy”. Pulsed high intensity focused ultrasound (HIFU) waves create, grow and collapse bubbles in tissue, which leads to puncturing of cell membranes and capillary walls. Cancer-derived microRNAs are thus released from the cells into the circulation and can be detected in a blood sample.

How can we make tumor cells release these biomarkers into the blood? The most straightforward way would be to puncture the cell membrane so that its content is released. One technology that allows for just that is high intensity focused ultrasound (HIFU). HIFU uses powerful, controlled ultrasound waves that are focused inside human body to ablate the targeted tissue at the focus without affecting the surrounding organs. Alternatively, if HIFU waves are sent in short, infrequent but powerful bursts, they cause mechanical disruption of tissue at the focus without any thermal effects. The disruption is achieved by small gas bubbles in tissue that appear, grow and collapse in response to the ultrasound wave– a phenomenon known as cavitation. Depending on the pulsing protocol employed, the outcome can range from small holes in cell membranes and capillaries to complete liquefaction of a small region of tumor. Using this technology, we seek to release biomarkers from tumor cells into the circulation in the effort to detect them using a blood test and avoiding biopsy.

To test this approach, we applied pulsed HIFU exposures to prostate cancer tumors implanted under the skin of laboratory rats, as illustrated in the image above. For image guidance and targeting we used conventional ultrasound imaging. Blood samples were collected immediately before and at periodic intervals after HIFU treatment and were tested for the presence of microRNAs that are associated with rat prostate cancer. The levels of these miRNAs were elevated up to 12-fold within minutes after the ultrasound procedure, and then declined over the course of several hours. The effects on tissue were evaluated in the resected tumors, and we found only micron-sized areas of hemorrhage scattered through otherwise intact tissue, suggesting damage to small capillaries. These data provided the proof of principle for the approach that we termed “ultrasound-aided liquid biopsy”. We are now working on identifying other classes of clinically valuable biomarkers, most notably tumor-derived DNA, that could be amplified using this methodology.