Apparatus and method for transurethral focussed ultrasound therapy

• US 5,895,356 A
• Filed: 11/15/1995
• Issued: 04/20/1999
• Est. Priority Date: 11/15/1995
• Status: Expired due to Fees

• Current Assignee: Ams Research Corporation (Endo International PLC)
• Original Assignee: American Medical Systems Incorporated (Endo International PLC)
• Inventors: Desilets, Charles S., Tihon, Claude, Andrus, W. Scott, Hovland, Claire T.
• Primary Examiner(s): Jaworski, Francis J.
• Application Number:
  US08/559,749
• Time in Patent Office: 1,252 Days
• Field of Search: 128/660.03, 128/662.03, 128/662.06, 601/3, 607/96-97, 607/101, 604/22, 600/439, 600/459, 600/462-3, 600/471, 600/105, 600/135
• US Class Current: 600/439
• CPC Class Codes: A61B 2017/00274 Prostate operation, e.g. prostatectomy, turp, bhp treatment
• CPC Class Codes: A61B 2017/22069 Immobilising; Stabilising
• CPC Class Codes: A61B 2018/00023 closed, i.e. without wound contact by the fluid
• CPC Class Codes: A61B 2018/00547 Prostate
• CPC Class Codes: A61B 2090/378 using ultrasound
• CPC Class Codes: A61N 7/022 intracavitary

Abstract

An apparatus and method for the treatment of diseases of the prostate, including BPH and prostate cancer, utilizing transurethrally applied focussed ultrasound energy to produce hyperthermal and thermotherapeutic effects in diseased tissue are disclosed. A first preferred embodiment of the apparatus relies on visual control; and a second preferred embodiment of the apparatus incorporates an integrated ultrasonic imaging and therapy transducer. The apparatus and method feature the close proximal placement of the ultrasound transducer to the diseased tissue to be treated, resulting in less attenuation of the beam and deposition of a greater fraction of the total emitted ultrasound energy in the selected portion of the diseased tissue. The ultrasound energy passes atraumatically through the urethral wall and other tissue not targeted. At the focal point of the ultrasound energy, substantial heating of diseased tissue to produce hyperthermal effects therein occurs, and even higher thermotherapeutic temperatures are attainable to produce coagulative necrosis of diseased tissue.

Claims

1. An apparatus for treatment of diseases of the prostate in a mammalian body, said apparatus comprising:

(a) a generator of a radio frequency electrical signal, having a frequency in the range of from about 1 MHz to about 10 MHz, capable of generating a constant power level and capable of operating at said constant power level for a period of time of at least 30 seconds;

(b) a transurethral probe transducer housing containing a transducer and a substantially circular output aperture having an area that is substantially circular, and corresponding coupling means and focusing means therefor, for converting at least a portion of said electrical signal into a beam of ultrasound energy, said beam having an area and sufficient power to produce thermal effects in prostatic tissue and to cause coagulative necrosis in selected portions of diseased prostatic tissue, and for coupling said ultrasound energy into diseased prostatic tissue, and focusing said ultrasound energy at a focal plane, such that said area of said beam of ultrasound energy at said focal plane is less than said area of said aperture and forms a substantially circular spot;

(c) delivery means for transurethrally introducing the transurethral probe transducer housing into the prostatic urethra of a mammalian body; and

(d) positioning means for fixing the transurethral probe transducer housing in a desired position in said prostatic urethra;

(e) at least one visualization means for enabling the remote observation of at least one of the positioning of the transurethral probe transducer housing, and the treatment of said diseased prostatic tissue, said visualization means being selected from the group (i-ii) consisting of;

(i) endoscopic means for viewing the position of the transurethral probe transducer housing within the urethra, and

(ii) diagnostic ultrasound means for generating an ultrasound imaging signal for producing an ultrasound image of at least a portion of the prostatic tissue to be treated.

2. The apparatus according to claim 1 wherein said delivery means is a tubular shaft housing having a proximal end, a distal end, an inner diameter, an outer diameter, a length, and at least one lumen extending therethrough, with the transurethral probe transducer housing cooperating with said delivery means and being positioned at said distal end of said delivery means.

3. The apparatus according to claim 1 in which said delivery means includes a flexible catheter having a proximal end, a distal end, and a longitudinal axis from said proximal end to said distal end, the maximum dimension of said catheter in a direction transverse to said longitudinal axis being not greater than 10 mm, with the transurethral probe transducer housing cooperating with said catheter and being positioned at said distal end of said catheter.

4. The apparatus according to claim 1 wherein said coupling means and said focusing means constitute a pair of elements selected from the group (i-iv) consisting of:

(i) a concave transducer for focusing, in communication with a concave quarter wave plate for coupling;

(ii) a planar transducer with a planoconcave lens made of an ultrasound transmitting material for focusing, in communication with a concave quarter wave plate for coupling;

(iii) a concave transducer in cooperation with a planar quarter wave plate, with a gap thereinbetween filled with an ultrasound transmitting material, such that said transducer and said ultrasound transmitting material in said gap provide focusing; and

said quarter wave plate provides coupling; and

(iv) a transducer made of a plurality of flat, ring-shaped elements forming a phased array for focusing, and a planar quarter wave plate for coupling.

5. The apparatus according to claim 4 wherein said focusing means and said coupling means is (i).

6. The apparatus according to claim 1 in which said ultrasound energy is focussed with a relative aperture less than about 1.7.

7. The apparatus according to claim 1 in which less than 80 percent of the emitted ultrasound energy is absorbed before reaching said diseased prostate tissue to be treated.

8. The apparatus according to claim 1 further including cooling means for limiting at least one temperature selected from the group consisting of:

(i) the temperature reached by said transducer and coupling means, and

(ii) the temperature reached by surrounding prostatic and non-prostatic tissue nearest said transducer and said coupling means.

9. The apparatus according to claim 8 in which said cooling means includes a source of cooling liquid external to said apparatus, means for allowing said cooling liquid to flow continuously from said source into said apparatus and into close proximity the transurethral probe transducer housing, and means for further allowing said cooling liquid to flow, after being warmed by absorption of heat from the transurethral probe transducer housing, out of said apparatus.

10. The apparatus according to claim 1 in which said positioning means includes an inflatable balloon for holding the transurethral probe transducer housing at a selected position in said prostatic urethra.

11. The apparatus according to claim 1 in which the ultrasound power output from the transurethral probe transducer housing required to produce coagulative necrosis does not exceed 10 watts.

12. The apparatus according to claim 1 wherein when said diagnostic ultrasound means is selected, total attenuation of said ultrasound imaging signal.

13. The apparatus according to claim 1 in which said generator of a radio frequency electrical signal includes means to vary the power during treatment according to a preprogrammed regime.

14. The apparatus according to claim 1 in which said generator of a radio frequency electrical signal includes means to detect a fault condition and automatically decrease the power conducted to said transducer in response to the detection of a fault condition.

15. The apparatus according to claim 1 further including intensity altering means for altering intensity of the ultrasound energy from a first predetermined level to a second, lower, predetermined level within a time not exceeding 5 seconds.

16. The apparatus according to claim 15 in which said intensity altering means includes means for altering said ultrasound intensity automatically at a preset time interval after irradiation with said ultrasound energy has begun.

17. The apparatus according to claim 1 further including means for detecting a return ultrasound echo from tissue in the vicinity of the focal point of the ultrasound energy.

18. The apparatus according to claim 17 in which at least one characteristic of said return ultrasound echo is used to define a point in time at which to alter the ultrasound energy intensity from a first predetermined level to a second predetermined level.

19. A method for treating of disease in a mammal, said method comprising:

irradiating a selected portion of diseased tissue in a mammalian body with ultrasound energy having a frequency in the range of from 1-10 MHz, utilizing an apparatus comprising;

(a) a generator of a radio frequency electrical signal, having a frequency in the range of from about 1 MHz to about 10 MHz, capable of generating a constant power level and capable of operating at said constant power level for a period of time of at least 30 seconds;

(b) the transurethral probe transducer housing including a single transducer with one or more piezoelectric elements and a substantially circular output aperture having an area that is substantially circular, and corresponding coupling means and focusing means therefor, for converting at least a portion of said electrical signal into a beam of ultrasound energy, said beam having an area and sufficient power to produce thermal effects in prostatic tissue and to cause coagulative necrosis in selected portions of diseased prostate tissue, and for coupling said ultrasound energy into diseased prostatic tissue, and focusing said ultrasound energy at a focal plane such that said area of said beam of ultrasound energy at said focal plane is less than said area of said aperture and forms a substantially circular spot;

(c) delivery means for transurethrally introducing the transurethral probe transducer housing into the prostatic urethra of a mammalian body; and

(d) positioning means for fixing the transurethral probe transducer housing in a desired position in said prostatic urethra;

(e) at least one visualization means for enabling the remote observation of at least one of the positioning of the transurethral probe transducer housing, and the treatment of said diseased prostatic tissue, said visualization means being selected from the group (i-ii) consisting of;

(i) endoscopic means for viewing the position of the transurethral probe transducer housing within the urethra, and (ii) diagnostic ultrasound means for generating an ultrasound imaging signal for producing an ultrasound image of at least a portion of the prostatic tissue to be treated;

such that;

said ultrasound energy is coupled into said diseased tissue to cause heat deposition near a focal point in the interior of said mammalian body;

the intensity of said ultrasound energy is initially high enough to cause denaturation and change in ultrasound attenuation properties in a small region of said diseased tissue near said focal point, within a time which is sufficiently short to prevent coagulative necrosis in non-diseased regions of tissue surrounding said diseased tissue; and

said intensity of said ultrasound energy is then reduced so that heat deposition occurs preferentially in said small region of said diseased tissue where ultrasound attenuation properties have been changed.

20. A method of treatment of prostate cancer comprising:

utilizing ultrasound energy to heat tumorous prostatic tissue and produce hyperthermal effects therein, said ultrasound energy being supplied by an apparatus comprising;

(a) a generator of a radio frequency electrical signal, having a frequency in the range of from about 1 MHz to about 10 MHz, capable of generating a constant power level and capable of operating at said constant power level for a period of time of at least 30 seconds;

(b) the transurethral probe transducer housing including a single transducer with one or more piezoelectric elements and an output aperture having an area, and corresponding focusing means and coupling means therefor, for converting at least a portion of said electrical signal into a beam of ultrasound energy, said beam having an area and sufficient power to produce thermal effects in prostatic tissue and to cause coagulative necrosis in selected portions of diseased prostatic tissue, and for coupling said ultrasound energy into diseased prostatic tissue, and focusing said ultrasound energy at a focal plane such that said area of said beam of ultrasound energy at said focal point is less than said area of said aperture;

(c) delivery means for transurethrally introducing the transurethral probe transducer housing into the prostatic urethra of a mammalian body; and

(d) positioning means for fixing the transurethral probe transducer housing in a desired position in said prostatic urethra;

(e) at least one visualization means for enabling the remote observation of at least one of the positioning of the transurethral probe transducer housing, and the treatment of said at diseased prostatic tissue, said visualization means being selected from the group (i-ii) consisting of;

(i) endoscopic means for viewing the position of the transurethral probe transducer housing within the urethra, and

(ii) diagnostic ultrasound means for generating an ultrasound imaging signal for producing an ultrasound image of at least a portion of the prostatic tissue to be treated;

and applying ionizing radiation therapy to said tumorous prostatic tissue in a mode selected from the group (iii-iv) consisting of;

(iii) prior to application of said ultrasound energy; and

(iv) simultaneous with application of said ultrasound energy.