Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2000-09-18
2002-04-16
Lateef, Marvin M. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S449000
Reexamination Certificate
active
06371912
ABSTRACT:
FIELD OF THE INVENTION
The present invention concerns ultrasound methods and apparatus for the identification and characterization of regions of altered stiffness in a target media.
BACKGROUND OF THE INVENTION
The early detection of breast cancer has been shown to significantly improve patient survival. Present methods of breast cancer detection include screening mammography and palpation, either by patient self-examination or clinical breast exam. Palpation relies on the manual detection of differences in tissue stiffness between breast lesions and normal breast tissue. The success of palpation is due to the fact that the elastic modulus (or Young's modulus) of malignant tumors is often an order of magnitude greater than that of normal breast tissue. That is, cancerous lesions feel “hard” or “stiff” as compared to normal breast tissue. See T. Krouskop et al.,
Ultrasonic Imaging
20, 260-274 (1998); A. Saravazyan et al.,
Acoustic Imaging
21, 223-240 (1995).
Recently, the use of ultrasonic radiation force to remotely characerize tissue stiffness has been proposed. One particular approach is referred to as remote palpation. In remote palpation, acoustic radiation force is used to apply localized forces within tissue, and the resulting tissue displacements are mapped using either ultrasonic correlation based methods, or other pattern matching methods. A volume of tissue that is stiffer than the surrounding medium (i.e., a lesion) may distribute the force throughout the tissue beneath it, resulting in larger regions of displacement, and smaller maximum displacements. Remote palpation is described in K. Nightingale,
Ultrasonic Generation and Detection of Acoustic Streaming to Differentiate Between Fluid-Filled and Solid Lesions in the Breast
(Ph.D. Thesis, Duke University, September 1997), and in K Nightingale et al.,
Proceedings of the
1997 IEEE
Ultrasonics Symposium,
1419-1422 (Toronto, Calif., October 1997).
U.S. Pat, No. 5,921,928 to Greenleaf uses sound and sonic waves to vibrate tissue and monitors the sound of the vibrating tissue. A disadvantage of such am approach is that different transmit and detection systems may be required, and multiple pushing cycles at a single location may be required.
Remote palpation has not yet been implemented in a form feasible for actual clinical diagnosis. Accordingly, there remains a need for new methods and systems to implement remote palpation.
SUMMARY OF THE INVENTION
The present invention is based upon the finding that an improved implementation of remote palpation in breast imaging can involve the use of multiple applications of radiation force in rapid succession throughout a two-dimensional plane in the target tissue, and the combination of the small, two-dimensional displacement maps from each force location into a single, larger remote palpation image. The use of multiple forcing locations may present a significant improvement in the remote palpation method, in that it may facilitate real-time, implementation of the method, which can allow more thorough interrogation of a suspicious region of tissue, as well as correlation and superposition of remote palpation images and conventional B-mode images. It may also reduce or even obviate the need for bulky, complex external fixtures during implementation of the method.
REFERENCES:
patent: 4913157 (1990-04-01), Pratt, Jr. et al.
patent: 5099848 (1992-03-01), Parker et al.
patent: 5107837 (1992-04-01), Ophir et al.
patent: 5524636 (1996-06-01), Sarvazyan et al.
International Search Report, International Application No. PCT/US01/11051.
Nightingale Kathryn R.
Nightingale Roger W.
Palmeri Mark L.
Trahey Gregg E.
Duke University
Imam Ali M.
Lateef Marvin M.
Myers Bigel & Sibley & Sajovec
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