Ultrasonic sensing by induced tissue motion

• US 6,488,626 B1
• Filed: 04/06/2000
• Issued: 12/03/2002
• Est. Priority Date: 04/07/1999
• Status: Active Grant

• Current Assignee: Riverside Research Institute
• Original Assignee: Riverside Research Institute
• Inventors: Alam, Sheikh Kaisar, Lizzi, Frederic L.
• Primary Examiner(s): Lateef, Marvin M.
• Assistant Examiner(s): Lin, Jeoyuh
• Application Number:
  US09/543,507
• Time in Patent Office: 971 Days
• Field of Search: 601/2, 601/3, 601/4, 600/459, 600/439
• US Class Current: 600/437
• CPC Class Codes: A61B 17/2258 integrated in a central portion of the shock wave apparatus
• CPC Class Codes: A61B 8/0858 involving measuring tissue layers, e.g. skin, interfaces
• CPC Class Codes: A61B 8/485 involving measuring strain or elastic properties
• CPC Class Codes: A61N 7/00 Ultrasound therapy lithotripsy A61B17/22, A61B17/225; massage using supersonic vibration A61H23/00 ; using ultrasound for introducing media into the body A61M37/0092
• CPC Class Codes: A61N 7/02 Localised ultrasound hyperthermia hyperthermia in general A61F7/00
• 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

Radiation pulses from a high energy therapeutic ultrasound system are used to stimulate tissue motion by radiation pressure. The tissue motion is monitored using a diagnostic ultrasound system.

Claims

1. A method for treating and evaluating tissue characteristics, comprising:

providing an ultrasonic therapeutic transducer for insonifying a region of tissue;

operating said ultrasonic therapeutic transducer to treat a region of tissue

providing an ultrasonic diagnostic transducer for transmitting and receiving signals from a region of tissue;

operating said ultrasonic therapeutic transducer to insonify a selected region of tissue and cause induced tissue displacement; and

operating said ultrasonic diagnostic transducer to observe said induced tissue displacement and thereby to evaluate mechanical characteristics of said tissue.

2. A method as specified in claim 1 wherein said therapeutic transducer illuminates said tissue along a radiation axis and wherein said diagnostic transducer transmits and receives ultrasonic signals along said radiation axis.

3. A method as specified in claim 1 wherein said operating an ultrasonic therapeutic transducer to induce tissue displacement comprises operating said transducer during a first selected time interval, and wherein said operating an ultrasonic diagnostic transducer comprise operating said diagnostic transducer during a second selected time interval immediately following said first selected time interval.

4. A method as specified in claim 1 further comprising observing baseline mechanical properties of said tissue prior to treating said region of tissue by irradiating said tissue with a reduced energy pulse of said therapeutic ultrasound radiation during a first selected time interval and observing mechanical characteristics of said tissue region during a second selected time interval immediately following said first time interval using said diagnostic ultrasound to thereby observe baseline mechanical characteristics of said tissue region.

5. A method as specified in claim 1 wherein said step of observing induced motion of said tissue region comprises irradiating said tissue region with a reduced energy pulse of said therapeutic ultrasound radiation during a first selected time interval and observing induced motion of said tissue region during a second selected time interval immediately following said first time interval using said diagnostic ultrasound.

6. A method as specified in claim 1 further comprising evaluating effectiveness of said treating said region of tissue from said evaluation of mechanical characteristics of said tissue.

7. A method as specified in claim 1 further comprising locating the focal volume of said therapeutic transducer by observing said induced tissue displacement using said ultrasonic diagnostic transducer.

8. A method as specified in claim 7 wherein said step of locating the focal volume of said therapeutic ultrasound radiation comprises irradiating said tissue region with a reduced energy pulse of said therapeutic ultrasound radiation during a first selected time interval and observing mechanical characteristics of said tissue region during a second selected time interval immediately following said first selected time interval using said diagnostic ultrasound to thereby locate the focal volume of said therapeutic radiation in said tissue.

9. A method of locating the focal volume of an ultrasonic therapeutic transducer in tissue, comprising:

detecting ultrasonic echoes from said tissue to determine initial structure thereof;

stimulating said tissue using ultrasonic radiation from said therapeutic transducer during a first selected time interval to induce tissue displacement; and

detecting diagnostic ultrasonic echoes from said tissue during a second time interval immediately following said first time interval thereby to detect a region of said tissue corresponding to the focal volume of said therapeutic transducer.

10. A method for treating tissue using high intensity ultrasound radiation comprising:

stimulating said tissue with high intensity ultrasonic radiation from an ultrasonic therapeutic transducer during a first selected time period;

detecting diagnostic ultrasonic echoes from said tissue using an ultrasonic diagnostic transducer during a second time interval immediately following said first time interval thereby to determine mechanical properties of said tissue; and

exposing said tissue to therapeutic high intensity ultrasonic pulses in a pulse sequence selected according to said mechanical properties.

11. A method as specified in claim 10 wherein determining mechanical properties includes determining elastic properties and wherein said pulse sequence is selected to have a pulse frequency corresponding to said elastic properties.

12. A method for measuring mechanical properties of tissue comprising:

stimulating a region of tissue with first and second high intensity ultrasonic radiation beams having first and second radiation axes; and

detecting diagnostic ultrasonic echoes from said region of tissues during a time interval immediately following said stimulating thereby to determine mechanical properties of said tissue.

13. A method as specified in claim 12 wherein said first and second high intensity beams are in sequential pulses and wherein said diagnostic echoes are detected during time intervals between said first and second sequential pulses.

14. A method of forming an image representing characteristics of a region of tissue, comprising:

stimulating said tissue with high intensity ultrasonic radiation from an ultrasonic therapeutic transducer during a first selected time interval to induce tissue displacement;

detecting ultrasonic echoes from said tissue using a diagnostic ultrasonic transducer during a second time selected time interval immediately following said first time interval thereby to measure mechanical characteristics of said tissue;

adjusting the tissue location of said diagnostic ultrasonic transducer and repeating said detecting to measure mechanical properties of said tissue over a plurality of tissue locations; and

combining said measurements to form an image of said tissue.

15. A method as specified in claim 14 wherein said adjusting the tissue location comprises maintaining a constant location of said high intensity ultrasonic radiation and adjusting the tissue location of said diagnostic ultrasonic echoes thereby to form a tissue image mapping a focal volume of said high-intensity radiation in said tissue.

16. A method as specified in claim 14 wherein said tissue includes a lesion and wherein said tissue image represents the location of said lesion.

17. A method as specified in claim 14 wherein said repeating said detecting includes repeating said stimulating.

18. A method for applying stress to tissue comprising insonifying said tissue with first and second therapeutic ultrasound beams having a common focal point in said tissue and having different beam directions toward said common focal point.

19. A method for applying stress to tissue as specified in claim 18 wherein said first and second beams are alternated.

20. A method for measuring tissue characteristics comprising applying stress to said tissue using the method of claim 18 and detecting diagnostic ultrasonic echoes from said tissue using an ultrasonic diagnostic transducer to monitor tissue motion resulting from said applied stress.

21. A method for applying stress to tissue comprising insonifying said tissue with first and second therapeutic ultrasound beams having a focal points spaced from each other in said tissue and having different beam directions toward said focal points.

22. A method for applying stress to tissue as specified in claim 21 wherein said first and second beams are alternated.

23. A method for measuring tissue characteristics comprising applying stress to said tissue using the method of claim 21 and detecting diagnostic ultrasonic echoes from said tissue using an ultrasonic diagnostic transducer to monitor tissue motion resulting from said applied stress.