Use of contrast agents to increase the effectiveness of high intensity focused ultrasound therapy
First Claim
1. A method for using an ultrasound contrast agent to enhance administration of a high intensity focused ultrasound (HIFU) therapy to a specific treatment site within a target area with a therapeutic ultrasonic transducer, comprising the steps of:
- (a) introducing a contrast agent to the target area, the contrast agent having a characteristic of altering reflection characteristics of an ultrasonic wave; and
(b) using the contrast agent to enhance the administration of the HIFU therapy in at least one of the following;
(i) producing an image in which a vascular system associated with the target area is clearly visible, and selecting the specific treatment site within the target area based on the visualization of the vascular structure in the image, thereby enabling the HIFU therapy to be targeted at the vascular structure;
(ii) enabling a focal point of the therapeutic ultrasonic transducer to be visualized in an image generated when the therapeutic ultrasonic transducer is energized at a power level insufficient to damage tissue, the focal point being readily visually identifiable in the image due to a change in the reflection characteristics of an ultrasonic wave produced by the therapeutic ultrasonic transducer caused by the contrast agent, thereby enabling the focal point of the therapeutic ultrasonic transducer to be targeted at the treatment site, and not at non-target tissue;
(iii) directing a focal point of the therapeutic ultrasonic transducer at a fluid filled volume containing the contrast agent, the fluid filled volume being disposed proximate to tissue to be treated, and energizing the therapeutic ultrasonic transducer at an energy level sufficient to induce cavitation in the contrast agent disposed in the fluid filled volume, the cavitation increasing an efficiency with which the HIFU therapy produces heat, said heat causing a therapeutic change in the tissue to be treated at the specific treatment site; and
(iv) directing a focal point of the therapeutic ultrasonic transducer at a fluid filled volume containing the contrast agent, the contrast agent acting as a shield to prevent tissue not disposed at the specific treatment site from being adversely affected by the HIFU therapy administered to the specific treatment site.
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Accused Products
Abstract
Ultrasound contrast agents are used to enhance imaging and facilitate HIFU therapy in four different ways. A contrast agent is used: (1) before therapy to locate specific vascular structures for treatment; (2) to determine the focal point of a HIFU therapy transducer while the HIFU therapy transducer is operated at a relatively low power level, so that non-target tissue is not damaged as the HIFU is transducer is properly focused at the target location; (3) to provide a positive feedback mechanism by causing cavitation that generates heat, reducing the level of HIFU energy administered for therapy compared to that required when a contrast agent is not used; and, (4) to shield non-target tissue from damage, by blocking the HIFU energy. Various combinations of these techniques can also be employed in a single therapeutic implementation.
310 Citations
31 Claims
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1. A method for using an ultrasound contrast agent to enhance administration of a high intensity focused ultrasound (HIFU) therapy to a specific treatment site within a target area with a therapeutic ultrasonic transducer, comprising the steps of:
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(a) introducing a contrast agent to the target area, the contrast agent having a characteristic of altering reflection characteristics of an ultrasonic wave; and
(b) using the contrast agent to enhance the administration of the HIFU therapy in at least one of the following;
(i) producing an image in which a vascular system associated with the target area is clearly visible, and selecting the specific treatment site within the target area based on the visualization of the vascular structure in the image, thereby enabling the HIFU therapy to be targeted at the vascular structure;
(ii) enabling a focal point of the therapeutic ultrasonic transducer to be visualized in an image generated when the therapeutic ultrasonic transducer is energized at a power level insufficient to damage tissue, the focal point being readily visually identifiable in the image due to a change in the reflection characteristics of an ultrasonic wave produced by the therapeutic ultrasonic transducer caused by the contrast agent, thereby enabling the focal point of the therapeutic ultrasonic transducer to be targeted at the treatment site, and not at non-target tissue;
(iii) directing a focal point of the therapeutic ultrasonic transducer at a fluid filled volume containing the contrast agent, the fluid filled volume being disposed proximate to tissue to be treated, and energizing the therapeutic ultrasonic transducer at an energy level sufficient to induce cavitation in the contrast agent disposed in the fluid filled volume, the cavitation increasing an efficiency with which the HIFU therapy produces heat, said heat causing a therapeutic change in the tissue to be treated at the specific treatment site; and
(iv) directing a focal point of the therapeutic ultrasonic transducer at a fluid filled volume containing the contrast agent, the contrast agent acting as a shield to prevent tissue not disposed at the specific treatment site from being adversely affected by the HIFU therapy administered to the specific treatment site. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for using an ultrasound contrast agent to enhance administration of a high intensity focused ultrasound (HIFU) therapy to a specific treatment site within a target area, comprising the steps of:
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(a) introducing a contrast agent into the target area, the contrast agent having a characteristic of altering reflection characteristics of an ultrasonic wave;
(b) positioning a scanning ultrasonic transducer and a therapeutic ultrasonic transducer generally adjacent to the target area;
(c) energizing the scanning ultrasonic transducer to produce an image of the target area;
(d) displaying the image of the target area;
(e) energizing the therapeutic ultrasonic transducer to produce ultrasonic waves generally directed toward the treatment site, but at a power level insufficient to adversely affect tissue;
(f) identifying a focal point of the therapeutic ultrasonic transducer in the image of the target area that is displayed, the focal point being readily identifiable due to a change in the reflection characteristics caused by the contrast agent; and
(g) moving the therapeutic ultrasonic transducer until its focal point, which is visible in the image of the target area, is directed at the treatment site. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A method for using a contrast agent to both enhance the ultrasound imaging of a target area and to facilitate providing a focused ultrasound therapy to a specific treatment site disposed within the target area, comprising the steps of:
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(a) introducing a contrast agent into the target area, the contrast agent altering reflection characteristics of an ultrasonic wave;
(b) positioning a scanning ultrasonic transducer and a therapeutic ultrasonic transducer generally adjacent to the specific treatment site;
(c) energizing the scanning ultrasonic transducer to scan the target area, producing an image of the target area;
(d) displaying the image of the target area;
(e) energizing the therapeutic ultrasonic transducer at a reduced power level to produce high intensity focused ultrasound (HIFU) beam, generally directed toward the treatment site, but at an energy insufficient to adversely affect tissue in the target area;
(f) observing a visual representation of a focal point of the HIFU beam in the image, the focal point being readily visible in the image due to a change in reflection characteristics caused by the contrast agent;
(g) positioning the therapeutic ultrasonic transducer as required until the focal point displayed in the image of the target area is directed at the treatment site; and
(h) energizing the therapeutic ultrasonic transducer at a greater power level sufficient to administer the focused ultrasound therapy to the treatment site. - View Dependent Claims (26, 27, 28, 29, 30, 31)
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Specification