College of Engineering University of Wisconsin-Madison
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BME MONITOR: The Biomedical Engineering Department Newsletter


2007 Newsletter
Featured articles

Experiential learning: BME undergrad design competition stresses real-world challenges

Research may yield improved treatment of diseased lungs

Translational research: Medicine, hand-delivered

Translational research:
Ultrasound waves reflect tissue mechanics

Translational research: 'Balloon' effect:
Blocking aneurysms

Translational research: For ACL repair,
closing the 'gap'

Translational research: Fast, efficient MR imaging

Translational research: Seven new projects launched

Graduate student service award honors Corrine Bahr

Regular Features

Message from the chair

Faculty news:
David Beebe cited as pioneer of miniaturization

In memoriam:
Prof. Paul Bach-y-Rita

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Engineer-clinician collaborations yield innovative, applied solutions

Funded via the W.H. Coulter Translational Research Partnership in Biomedical Engineering, these research projects recently concluded in year one of the partnership. This partnership fosters early-stage collaborations between University of Wisconsin biomedical engineering researchers and practicing physicians that will enable researchers to deliver their advances more quickly to patients.

Ultrasound waves reflect tissue mechanics

Ray Vanderby

Ray Vanderby
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Decorative initial cap In nature, mammals such as bats and whales emit sounds and, from the echoes that return, locate and identify objects in their environment. In a similar manner, Professor Ray Vanderby, Assistant Professor Lee Kaplan (also orthopedics & rehabilitation) and Associate Professor Patricia Keely (also pharmacology) are using ultrasound waves to identify mechanical properties of tissue that might, for example, help physicians distinguish various types of cancerous tumors. They call this noninvasive method an acoustoelastic biopsy. They also are using ultrasound waves to determine functional tissue loading, such as stretch in a ligament or tendon. They call this an acoustoelastic strain gauge.

Initially, they studied reflected waves from loaded, or stretched, and unloaded, or relaxed, tendons. When, in side-by-side experiments, they delivered ultrasound waves to the two tendons, they found that the reflected wave amplitude and the wave propagation velocity were higher in the loaded, stiffer tendon than in the unloaded tendon. From these waves, they determine material stiffness, to identify tissues by their material properties, and strain, to measure functional loadings.

To apply this concept to orthopedics, Vanderby and Kaplan are developing clinical protocols to diagnose rotator cuff tendon damage, via loading patterns, and healing, via mechanical properties. To apply the concept to tumor diagnostics, Vanderby and Keely deliver an ultrasound signal, then palpitate, or compress the tumor. As the tumor compresses, it becomes thinner and stiffer and the size and velocity of the reflected ultrasound signal respond accordingly.

In laboratory tests on mouse models of the two most common types of breast cancer tumors, they developed “signature” ultrasound signal patterns for those tumors, reflecting their different mechanical behaviors based only on ultrasound information. “We can estimate the mechanical behavior quite well; we call it our stiffness gradient index method of characterization,” says Vanderby. “But then also we can distinguish one type of tumor from another with high specificity and high sensitivity.”

Building on their research with isolated tissues in the laboratory, Vanderby, Kaplan and Keely now are testing their methods in vivo.

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Copyright 2007 The Board of Regents of the University of Wisconsin System

Date last modified: Monday,30-July-2007 15:43:00 CDT
Date created: 30-July-2007



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