Project: Research project

Project Details


Low-frequency material properties of tissues, such as stiffness or
mobility, have been shown to be associated with diseases such as
atherosclerosis and neoplasms. The long-term goal of this program is
to produce methods for measuring and imaging low-frequency material
properties of biologic tissues with high resolution and contrast using
our novel ultrasound stimulated acoustic emission method. The resulting
noninvasive measures of arterial stiffness would be amenable to studies
in populations. In the currently proposed program we pursue the goal of
detecting and imaging calcified and non-calcified placque within excised
arteries, and in animal models, with an imaging technique that uses
acoustic emission to map the mechanical response of an object to local
cyclic radiation forces produced by interfering ultrasound beams. The
novelty of our approach is that the induced motion of tissue is detected
by its acoustic emission resulting in a sensitivity to displacement of
the order of a few Angstroms. The method, which we call "Ultrasonic
Stimulated Acoustic Emission (USAE)", appears well suited to both micro-
detection and macro-detection of calcification and less hard tissues.
The approach results from ultrasonic radiation pressure stimulation of
vibration using dual beam or confocal transducer geometries. This
program studies excised human and in vivo swine arteries, with and
without disease, comparing USAE images and spectra to histologic
analyses of the arteries. Preliminary results clearly delineate
calcified, non-calcified, and normal arterial segments in USAE images
obtained at acoustic emission frequencies ranging from 7 kHz to 41 kHz.
Very early detection of atherosclerosis using a noninvasive instrument
such as a modern ultrasound scanner equipped with ultrasonic stimulated
acoustic emission, would provide a useful method of delineating non-
symptomatic atherosclerosis patients with nascent disease from those
without this systemic occult disease. Successful completion of this
program will result in USAE methods that are immediately applicable to
clinical studies.
StatusNot started


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