Determining material stiffness using multiple aperture ultrasound
First Claim
1. A method of determining a stiffness of a tissue with ultrasound, the method comprising the steps of:
- forming a baseline image of a region of interest with a ping-based ultrasound imaging system;
transmitting an ultrasonic pulse with a shear-wave-initiating transducer, the ultrasonic pulse being configured to induce a propagating shear wave in the region of interest;
imaging the region of interest with the ping-based ultrasound imaging system to capture a first image frame and a second image frame of the propagating shear wave as it moves through the region of interest, wherein capturing the first frame comprises;
transmitting a first unfocused ultrasound ping from a first transmitter transducer element of the ping-based ultrasound imaging system;
forming a first image layer using echoes of only the first ultrasound ping received by elements of a first receive aperture of the ping-based ultrasound imaging system with an electronic controller of the ping-based ultrasound imaging system;
forming a second image layer using echoes of only the first ultrasound ping received by elements of a second receive aperture of the ping-based ultrasound imaging system with the electronic controller;
combining the first image layer and the second image layer with the electronic controller to form the first frame;
wherein capturing the second frame comprises;
transmitting a second unfocused ultrasound ping from the first transmitter transducer element of the ping-based ultrasound imaging system;
forming a third image layer using echoes of only the second ultrasound ping received by elements of the first receive aperture of the ping-based ultrasound imaging system with the electronic controller;
forming a fourth image layer using echoes of only the second ultrasound ping received by elements of the second receive aperture of the ping-based ultrasound imaging system with the electronic controller;
combining the third image layer and the fourth image layer with the electronic controller to form the second frame;
subtracting the baseline image from the first image frame with the electronic controller of the ping-based ultrasound imaging system to obtain a first difference frame;
subtracting the baseline image from the second image frame with the electronic controller to obtain a second difference frame;
determining a position of the propagating shear wave in the first and second difference frames with the electronic controller; and
calculating a first propagation speed of the propagating shear wave in the region of interest from the positions in the first and second difference frames with the electronic controller.
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Abstract
Changes in tissue stiffness have long been associated with disease. Systems and methods for determining the stiffness of tissues using ultrasonography may include a device for inducing a propagating shear wave in tissue and tracking the speed of propagation, which is directly related to tissue stiffness and density. The speed of a propagating shear wave may be detected by imaging a tissue at a high frame rate and detecting the propagating wave as a perturbance in successive image frames relative to a baseline image of the tissue in an undisturbed state. In some embodiments, sufficiently high frame rates may be achieved by using a ping-based ultrasound imaging technique in which unfocused omni-directional pings are transmitted (in an imaging plane or in a hemisphere) into a region of interest. Receiving echoes of the omnidirectional pings with multiple receive apertures allows for substantially improved lateral resolution.
480 Citations
17 Claims
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1. A method of determining a stiffness of a tissue with ultrasound, the method comprising the steps of:
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forming a baseline image of a region of interest with a ping-based ultrasound imaging system; transmitting an ultrasonic pulse with a shear-wave-initiating transducer, the ultrasonic pulse being configured to induce a propagating shear wave in the region of interest; imaging the region of interest with the ping-based ultrasound imaging system to capture a first image frame and a second image frame of the propagating shear wave as it moves through the region of interest, wherein capturing the first frame comprises; transmitting a first unfocused ultrasound ping from a first transmitter transducer element of the ping-based ultrasound imaging system; forming a first image layer using echoes of only the first ultrasound ping received by elements of a first receive aperture of the ping-based ultrasound imaging system with an electronic controller of the ping-based ultrasound imaging system; forming a second image layer using echoes of only the first ultrasound ping received by elements of a second receive aperture of the ping-based ultrasound imaging system with the electronic controller; combining the first image layer and the second image layer with the electronic controller to form the first frame; wherein capturing the second frame comprises; transmitting a second unfocused ultrasound ping from the first transmitter transducer element of the ping-based ultrasound imaging system; forming a third image layer using echoes of only the second ultrasound ping received by elements of the first receive aperture of the ping-based ultrasound imaging system with the electronic controller; forming a fourth image layer using echoes of only the second ultrasound ping received by elements of the second receive aperture of the ping-based ultrasound imaging system with the electronic controller; combining the third image layer and the fourth image layer with the electronic controller to form the second frame; subtracting the baseline image from the first image frame with the electronic controller of the ping-based ultrasound imaging system to obtain a first difference frame; subtracting the baseline image from the second image frame with the electronic controller to obtain a second difference frame; determining a position of the propagating shear wave in the first and second difference frames with the electronic controller; and calculating a first propagation speed of the propagating shear wave in the region of interest from the positions in the first and second difference frames with the electronic controller. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification