Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1999-09-15
2001-07-24
Vo, Peter (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S449000
Reexamination Certificate
active
06264609
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a medical device, and more particularly to ultrasound apparatus and methods for the identification and characterization of tissues and their constituent structures.
BACKGROUND OF THE INVENTION
Methods and apparatus which utilize ultrasound energy for diagnostic imaging of targeted anatomical organs and blood flow are known. Typically, ultrasound energy is directed into and scattered from body tissues. The amplitude envelope of the scattered ultrasound energy known as an echo is detected and displayed to form an image which characterizes the targeted structures.
Virtually all commercial medical ultrasound imaging systems form images from the amplitude envelope of the scattered ultrasound energy that is returned by an interface of different organ tissue types having different acoustic impedances. Although the prior art systems attempt to delineate various body organs, they cannot identify different types of organ tissue or identify various structures within the same tissue. Further, these systems fail to make use of the phase information of the scattered ultrasound energy which is particularly useful to image and identify tissues and their various constituent structures.
SUMMARY OF THE INVENTION
The present invention is an ultrasound apparatus and method for tissue characterization. The invention uses parametric imaging where the parameter or feature of interest in the tissue is the randomness of the scatterers produced by the tissue relative to each other in a region of interest in the tissue. A parametric image forming a feature space is rendered and gradients in the feature space can be used to identify transitions from one tissue type to another.
The invention establishes a physical model of preselected tissue that is used to simulate an ultrasound image formation process. The invention simulates an ultrasound image structure comprising the pre-selected tissue. In addition, the invention can compare the simulated data with scanned images of actual pre-selected tissue. Further, the invention can detect tissue transitions using gradient or other edge detection techniques in a feature space where the substrate for the algorithm is a metric of randomness of the scatterers in the region of interest.
Thus, the invention includes three distinct components that may be used separately or in combination to determine tissue structure and establish boundaries from this structure.
First, the invention utilizes the randomness of the scatterers to build a parametric image of the tissue from the rf signal. This image, or map, illustrates tissue structure and tissue boundaries. Parametric descriptions and metrics using randomness of the scatterers, can be used to characterize the tissue. The standard gain control (SGC) map defined herein is a specific example of such a metric.
Second, boundary detection can be accomplished by applying gradient or other edge detection methods to the parametric or feature map in order to quantify spatial characteristics and dimensions of the tissue.
Third, a method of simulating tissue structure and the response of the tissue to ultrasound energy has been established. The simulated tissue structure can be compared to the tissue structure determined from an actual ultrasound scan in order to determine tissue type and tissue boundaries.
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Fan Liexiang
Herrington David M.
Santago, II Peter
Dann Dorfman Herrell & Skillman P.C.
Imam Ali M.
Vo Peter
Wake Forest University
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