Development of Novel, Clinically Applicable Ultrasound Imaging Techniques
The development of novel, clinically applicable ultrasound imaging techniques is the primary goal of our laboratory's research. We are particularly interested in the use of motion-tracking techniques to enhance the contrast of ultrasound images. Motion of tissues, both physiological and artificial, can reveal the differences in tissue stiffness and type, as well as the presence of implanted devices. Furthermore, detection and tracking of tissue motion can guide the delivery of therapeutic agents. The interaction of ultrasound with tissue, statistical properties of ultrasound echoes and signal processing techniques are the topics we study in order to achieve these goals.
Acoustic Radiation Force Impulse (ARFI) imaging is one technique we are investigating. ARFI imaging uses short (<0.1ms) bursts of ultrasound to induce small but measurable (2-20 microns) displacements in tissue. The response of the tissue to this impulsive excitation is determined by material properties. By measuring this response we produce images with contrast not present in ordinary ultrasound images (B-scans).
Magnetically induced vibration of brachytherapy seeds, combined with ultrasonic motion tracking, allows us to produce high contrast images of brachytherapy seeds embedded in tissue. Brachytherapy seeds are ordinarily difficult to image with ultrasound, and their accurate placement is necessary for effective therapy. Our magnetically induced motion imaging (MIMI) technique could serve as an enabling technology for real-time treatment planning of prostate brachytherapy.
Ultrasound Imaging of Tissue Stiffness by Spatially Modulated Acoustic Radiation Force Impulse (SM-ARFI)
Technology ID: 2-11149-07012
U.S. Patent Application Number 12/118,359 filed on 05/09/2008
A method for determining a shear modulus of an elastic material with a known density value is provided. In this method, a spatially modulated acoustic radiation force is used to initially generate a disturbance of known spatial frequency or wavelength. The propagation of this initial displacement as a shear wave is measured using ultrasound tracking methods. A temporal frequency is determined based on the shear wave. The shear modulus of the elastic material at the point of excitation may be calculated using the values of the spatial wavelength, material density, and temporal frequency.