METHODS AND APPARATUS FOR FOCUSED ULTRASOUND APPLICATION

• US 20110118602A1
• Filed: 01/21/2011
• Published: 05/19/2011
• Est. Priority Date: 10/25/1999
• Status: Active Grant

• Current Assignee: Otsuka Medical Devices Co., Ltd. (Otsuka Holdings Company Limited)
• Original Assignee: Kona Medical, Inc.
• Inventors: Zhang, Jimin, Perozek, David M., Weng, Lee
• Granted Patent: US 8,388,535 B2
• Time in Patent Office: Days
• US Class Current: 600/439
• CPC Class Codes: A61B 17/0057 Implements for plugging an opening in the wall of a hollow or tubular organ, e.g. for sealing a vessel puncture or closing a cardiac septal defect sutures A61B17/04; closing rectum or urethra near body surface A61F2/0009
• CPC Class Codes: A61B 2017/00504 Tissue welding
• CPC Class Codes: A61B 2017/00641 for closing fistulae, e.g. anorectal fistulae
• CPC Class Codes: A61B 2017/00907 for light
• CPC Class Codes: A61B 2090/062 penetration depth
• CPC Class Codes: A61B 2090/378 using ultrasound
• CPC Class Codes: A61B 2090/3904 specially adapted for marking specified tissue
• CPC Class Codes: A61B 2090/3937 Visible markers
• CPC Class Codes: A61B 2562/164 the sensor is mounted in or on a conformable substrate or carrier
• CPC Class Codes: A61B 8/4422 related to hygiene or sterilisation
• CPC Class Codes: A61N 7/02 Localised ultrasound hyperthermia hyperthermia in general A61F7/00
• CPC Class Codes: G10K 11/32 characterised by the shape of the source
• CPC Class Codes: G10K 11/346 using phase variation

Abstract

An ultrasonic applicator unit (2) is used diagnostically to locate a puncture wound (316) in an artery and then therapeutically to seal the puncture wound with high intensity focused ultrasound (HIFU). A control unit (6) coupled to the applicator unit includes a processor (74) that automates the procedure, controlling various parameters of the diagnostic and therapeutic modes, including the intensity and duration of the ultrasonic energy emitted by the applicator unit. A protective, sterile acoustic shell (4), which is intended to be used with a single patient and then discarded, is slipped over the applicator unit to protect against direct contact between the applicator unit and the patient and to maintain a sterile field at the site of the puncture. The apparatus and method are particularly applicable to sealing a puncture made when inserting a catheter into an artery or other vessel. Several different procedures are described for locating the puncture wound, including imaging the vessel in which the puncture is disposed and use of a locator rod to determine the disposition of the puncture along the longitudinal axis of the artery.

Claims

1. A focused ultrasound system, comprising:

an ultrasound transducer device having a plurality of transducer elements;

a control unit coupled to the transducer elements, wherein the control unit is configured to individually control delivery of acoustic energy from the transducer elements along an ultrasound energy path towards a target tissue such that a delivered energy dose at the target tissue remains at or above a first level, while a delivered energy dose at tissue in the ultrasound energy path and outside of the target tissue remains at or below a second delivered energy dose, wherein the second delivered energy dose is less than the first delivered energy dose.

2. The system of claim 1, wherein the first delivered energy dose is greater than about 100 joules/sq. cm, but less than about 5,000 joules/sq. cm.

3. The system of claim 1, wherein the first delivered energy dose raises a measured temperature of the target tissue to between about 60 and about 100 degrees Celsius for a predetermined period of time.

4. The system of claim 1, wherein the second delivered energy dose is such that tissue in the ultrasound energy path and outside of the target tissue is not exposed to a temperature-time exposure that will result in pain or irreversible tissue damage.

5. The system of claim 1, wherein the control circuitry is configured to control one or more of the transducer elements to provide a beam geometry that does not harm tissue in the ultrasound energy path and outside of the target tissue.

6. A method for determining exposure parameters for a focused ultrasound system used to target a tissue in a patient, the method comprising:

providing a focused ultrasound system including at least one ultrasound transducer having a plurality of transducer elements;

identifying a target tissue to be treated;

identifying tissue along an ultrasound energy path outside of the target tissue;

estimating energy intensities at the target tissue and the tissue along the ultrasound energy path outside of the target tissue based at least in part on the relative position between the transducer(s) and the target tissue and the relative position between the transducer(s) and the tissue along the ultrasound energy path outside of the target tissue; and

determining exposure parameters for the focused ultrasound system that cause the estimated energy intensity delivered to the target tissue to remain above a first level while the estimated energy at the tissue along the ultrasound energy path outside of the target tissue remains below a second level, wherein the second level is less than the first level.

7. The method of claim 6 wherein the identifying a target tissue to be treated step comprises obtaining an image of the target tissue.

8. A method for creating a treatment plan for treating a patient using a focused ultrasound system, the focused ultrasound system comprising a transducer having a plurality of transducer elements, the method comprising:

creating a model representing energies to be delivered to a patient by respective transducer elements of the transducer;

calculating an energy density based on the model at a tissue region along an ultrasound energy path from the transducer elements, the tissue region associated with patient body tissue that is outside of tissue to be treated;

determining whether the calculated energy density at the tissue region exceeds a threshold;

determining adjustments to operational parameters of one or more of the transducer elements such that the energy density at the tissue region is below the threshold while maintaining a minimum energy intensity at the tissue to be treated; and

creating a treatment plan based on the model and the adjustments.

9. A method for determining one or more operational parameters of a focused ultrasound system for therapeutic application to a patient, the method comprising:

providing a focused ultrasound system including at least one transducer element;

identifying a target tissue to be exposed with ultrasonic energy emitted from the focused ultrasound system;

estimating an acoustic path length between the transducer element(s) and the target tissue;

estimating an acoustic attenuation value based at least in part on the acoustic path length; and

determining one or more operational parameters of the focused ultrasound system based at least in part on the acoustic attenuation value, wherein the parameters ensure that a therapeutic energy dose is delivered from the focused ultrasound system to the target tissue while assuring that interpath tissue is not exposed to an energy that will result in tissue damage.

10. The method of claim 9, wherein the therapeutic energy dose causes a collagen layer in the target tissue to reach a temperature of between about 60 degrees Celsius and about 100 degrees Celsius.

11. The method of claim 9, wherein the estimating an acoustic attenuation value based at least in part on the acoustic path length step comprises employment of A-mode attenuation measurements.

12. The method of claim 9, wherein the estimating an acoustic attenuation value based at least in part on the acoustic path length step comprises the use of a look table based on predetermined empirical measurements.

13. The method of claim 9, wherein the target tissue is identified through detecting a Doppler signal.

14. The method of claim 9, further comprising an over-scan of the target tissue to compensate for targeting ambiguity.

15. The method of claim 9, wherein the operational parameters include at least ultrasound intensity level, exposure interval, and scan geometry.

16. The method of claim 9, wherein the target tissue comprises collagen overlaying a vascular target.

17. The method of claim 9, wherein the estimating an acoustic attenuation value based at least in part on the acoustic path length step is further based at least in part on patient size and weight.

18. The method of claim 9, wherein pulse-echo lines of interrogation are utilized to assist in the identification of the target tissue.

19. A method for determining one or more operational parameters of a focused ultrasound system for therapeutic application to a vascular target, the method comprising:

providing a focused ultrasound system including at least one transducer element;

utilizing imaging to identify the vascular target to be exposed with ultrasonic energy emitted from at least one of the transducer element(s);

estimating an acoustic path length between at least one of the transducer element(s) and the vascular target;

estimating an acoustic attenuation value based at least in part on the acoustic path length; and

determining one or more operational parameters of the focused ultrasound system based at least in part on the acoustic attenuation value, wherein the parameters ensure that a therapeutic energy dose is delivered from the focused ultrasound system to the vascular target while assuring that interpath tissue is not exposed to an energy that will result in tissue damage.

20. The method of claim 19, wherein the imaging comprises Doppler imaging.

21. The method of claim 19, wherein the imaging comprises pulse-echo lines of interrogation.

22. The method of claim 19, wherein the focused ultrasound system comprises an imaging transducer and a therapy transducer.

23. The method of claim 22, wherein the imaging transducer is the same as the therapy transducer.

24. A focused ultrasound system, comprising:

an ultrasound transducer device having a plurality of transducer elements;

a control unit coupled to the transducer elements, wherein the control unit is configured to individually control delivery of acoustic energy from the transducer elements along an ultrasound energy path towards a vascular target tissue such that a delivered energy dose at the vascular target tissue remains at or above a first level, while a delivered dose at tissue in the ultrasound energy path and outside of the vascular target tissue remains at or below a second delivered energy dose, wherein the second delivered energy dose is less than the first delivered energy dose.

25. The system of claim 24, wherein at least one of the transducer elements comprises an imaging transducer configured to image the vascular target tissue.

26. The system of claim 25 wherein the imaging transducer is configured to emit pulse-echo lines of interrogation.