Ultrasonic elasticity imaging method and device

• US 5,678,565 A
• Filed: 02/27/1996
• Issued: 10/21/1997
• Est. Priority Date: 12/21/1992
• Status: Expired due to Term

• Current Assignee: Armen P. Sarvazyan
• Original Assignee: Artann Corporation
• Inventors: Sarvazyan, Armen Paruir
• Primary Examiner(s): NASSER, ROBERT L
• Application Number:
  US08/607,639
• Time in Patent Office: 602 Days
• Field of Search: 128/774, 128/660.01, 128/660.02, 128/660.06, 128/660.07, 128/660.08, 128/661.03, 73/788, 73/789, 73/790, 73/794-6, 73/798, 73/573
• US Class Current: 600/587
• CPC Class Codes: A61B 1/0052 Constructional details of control elements, e.g. handles
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 2562/046 in a matrix array
• CPC Class Codes: A61B 5/0053 by applying pressure, e.g. compression, indentation, palpation, grasping, gauging
• CPC Class Codes: A61B 5/036 by means introduced into body tracts A61B5/032 and A61B5/035 take precedence
• CPC Class Codes: A61B 5/064 using markers A61B5/062 takes precedence
• CPC Class Codes: A61B 5/4312 Breast evaluation or disorder diagnosis A61B5/0091 takes precedence
• CPC Class Codes: A61B 8/0825 for diagnosis of the breast, e.g. mammography
• CPC Class Codes: A61B 8/0833 involving detecting or locating foreign bodies or organic structures
• CPC Class Codes: A61B 8/485 involving measuring strain or elastic properties
• CPC Class Codes: G01S 7/52042 determining elastic properties of the propagation medium or of the reflective target diagnostic techniques involving the measurement of strain A61B8/485

Abstract

A method and a device for noninvasively identifying a region of the tissue having a different elasticity than the surrounding tissue by simultaneously measuring strain and stress patterns in the tissue portion using an ultrasonic imaging system combined with a pressure sensing array. In a particular embodiment, a pressure sensing array made of a sound transparent film inserted between the ultrasonic scanner probe and the tissue measures pressure pattern on the surface of the tissue when the tissue portion is deformed while the scanner detects internal strain pattern. The ultrasonic scanner probe with the attached pressure sensing array serves as a pressure exerting member causing a deformation of the tissue and creating stress and strain in the tissue portion.

Claims

1. A method of identifying a region within a tissue portion having a different elasticity than the surrounding tissue comprising:

causing a deformation of the tissue and creating stress and strain in the tissue portion by an ultrasonic scanner probe pressed against the tissue portion;

determining both of the properties of the created stress and strain in the tissue portion by measuring pressure distribution using a pressure sensing array to obtain a stress pattern on the surface of the tissue portion and imaging internal tissue structure by said ultrasonic scanner to provide the internal strain pattern after deformation, wherein the pressure sensing array and the ultrasonic scanner probe are located at the same location on the surface of the tissue portion;

defining a model of the tissue portion with homogeneous tissue and with given boundary conditions for the tissue portion;

calculating patterns of the both of the properties of stress and strain for the defined model;

comparing the determined patterns obtained in the determining step and the respective calculated patterns obtained in the calculating step, the differences between the patterns indicating the presence and location of a different elasticity region of tissue within the tissue portion; and

evaluating elasticity characteristics of the tissue portion by varying a spatial distribution of modulus of elasticity in the defined model to minimize the difference between the determined patterns from the determining step and the respective calculated patterns for the defined model, thereby solving an inverse mechanical problem and obtaining spatial distribution of elasticity modulus in the tissue portion.

2. A device for determining variations in elasticity of bodily tissue comprising:

means for applying pressure to an accessible surface of said tissue to provide at least two conditions of compression loading of the tissue to be examined, said means comprising an ultrasonic scanner probe;

means for measuring both of the properties of the created stress and strain in the tissue portion, said means comprising a pressure sensing array to provide pressure pattern on the surface of the tissue portion, and an ultrasonic scanner to provide the internal strain pattern in the tissue portion after deformation, wherein the pressure sensing array and the probe of the ultrasonic scanner are adapted to be located at the same location on the surface of the tissue portion; and

means for processing the measured data and obtaining spatial distribution of elasticity modulus in the tissue portion.

3. The device of claim 2, wherein said pressure sensing array is made out of a sound transparent film positioned between the tissue and the surface of an ultrasonic scanner probe facing the tissue.

4. The device of claim 3, wherein the pressure sensing array is made out of piezoelectric polymer film.

5. The device of claim 3, wherein the pressure sensing array is a pressure sensitive resistor based array.

6. A method for determining variations in elasticity of bodily tissue comprising the steps:

applying pressure by ultrasonic scanner probe to an accessible surface of said tissue to provide at least two conditions of compression loading of the tissue to be examined;

measuring both of the properties of the created stress and strain in the tissue portion, using a pressure sensing array to provide pressure pattern on the surface of the tissue portion, and an ultrasonic scanner to provide the internal strain data in the tissue portion after deformation; and

processing the measured data and obtaining spatial distribution of elasticity modulus in the tissue portion.