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Applied Mathematics Colloquium
Friday, September 19, 11:30 am
Cullimore Lecture Hall II
New
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Shear Stiffness Imaging as an Early
Diagnostic Tool:
New Applications and New Imaging Algorithms
Joyce McLaughlin
Department of Mathematical Sciences
Rensselaer Polytechnic Institute
Abstract
We target imaging the biomechanical properties that the doctor feels in a
palpation exam. Two candidates are shear
wave speed and shear wave viscoelastic properties such as wave spreading and
attenuation. We utilize dynamic displacement data where inventive experiments
result in movies of propagating shear waves in regions of interest. Displacement is on the order of microns and
linear (visco) elastic models model the propagating waves. The goal then is to utilize the data and the
mathematical models to create images of the biomechanical properties. Arrival
Time algorithms utilize the propagating front and nonlinear Log-Elastographic
Algorithms control exponential growth artifacts. Applications include: early identification of
the onset of fibrosis in the liver; tumor identification in the prostate; and
breast tumor identification and differentiation.
Experiments include: (1) a single frequency
excitation is made on the surface of the body exciting a time harmonic shear
wave throughout the region of interest; (2) two, different but nearly equal,
single frequency excitations are made on two different lines or at two
different points, creating a slowly moving traveling wave; and (3) a line
source either on the surface of the body or in the interior of the body creates
a propagating shear wave with a front.
Measurements are made with Ultrasound or MRI to obtain movies of the
wave. Experimentalists who have provided
data are: Richard Ehman, Mayo Clinic;
Kevin Parker,
The talk will include discussion of experiments, mathematical models, algorithms and images with measured data.