US20070197918A1 - Endo-cavity focused ultrasound transducer - Google Patents

Abstract

An apparatus for delivering acoustic energy to a target site adjacent a body passage includes first and second elongate members, each carrying one or more transducer elements on their distal ends. The first and/or second elongate members include connectors for securing the first and second elongate members together such that the transducer elements together define a transducer array. The first and second elongate members are introduced sequentially into a body passage until the transducer elements are disposed adjacent a target site. Acoustic energy is delivered from the transducer elements to the target site to treat tissue therein. In another embodiment, the apparatus includes a tubular member and an expandable structure carrying a plurality of transducer elements. The structure is expanded between a contracted configuration during delivery and an enlarged configuration when deployed for delivering acoustic energy to a target site adjacent the body passage.

Description

RELATED APPLICATION DATA
• This application is a continuation of U.S. application Ser. No. 10/452,061, filed Jun. 2, 2003, which is hereby incorporated by reference in its entirely.
FIELD OF THE INVENTION
• The present invention relates generally to apparatus and methods for delivering acoustic energy, and more particularly to apparatus and methods for delivering diagnostic and/or therapeutic ultrasonic energy from a transducer disposed within a body of a subject.
BACKGROUND
• Devices and systems using acoustic energy, particularly within the ultrasonic range (acoustic waves with a frequency greater than about twenty kilohertz (20 kHz), and more typically between fifty kiloHertz and five Megahertz (0.05-5 MHz)), have been used to diagnose and treat patients. For example, ultrasonic energy may be employed to obtain images of a region of a patient during a diagnostic or therapeutic procedure. In addition, ultrasound systems have been used for treating tissue, e.g., by focusing acoustic energy towards a target tissue region within a patient, such as a cancerous or benign tumor, to necrose or otherwise heat the tissue region. For example, one or more piezoelectric transducers may be disposed adjacent a patient's body and used to deliver high intensity acoustic waves, such as ultrasonic waves, to an internal tissue region of a patient to treat the tissue region. An exemplary focused ultrasound (“FUS”) system is disclosed in U.S. Pat. No. 4,865,042 issued to Umemura et al.
• Focused ultrasound procedures may allow a patient to be treated without requiring invasive surgery. Because ultrasonic transducers are generally disposed adjacent to the patient, however, the acoustic path to a target tissue region may be at least partially obstructed, e.g., by anatomical objects such as bones or cavities, within the patient's body. Furthermore, acoustic energy may not be adequately focused at a location deep within a body, e.g., because the resulting focal zone may be too large to provide an effective and safe treatment. As such, it is preferable to place the transducer as close to a target site as possible.
• To deliver acoustic energy to locations deep within the body, it has been suggested to use natural body passages to place an acoustic transducer closer to a target site. For example, U.S. Pat. No. 5,666,954 discloses a transducer that may be inserted into the rectal canal through the rectal orifice to treat prostate cancer. Natural body passages, however, may limit the size of the transducer that may be introduced.
• Generally, a relatively large transducer provides better control over the size and intensity of the resulting focal zone. The size of a transducer that may be delivered inside a body passage may be limited by the size of a body orifice at the entry point for the transducer. For example, the size of a transducer used for treating prostate cancer may be limited by the maximum perimeter of the rectal orifice.
• Accordingly, apparatus and methods for delivering acoustic energy within a patient's body would be useful.
SUMMARY OF THE INVENTION
• The present invention is directed to apparatus, systems, and methods for delivering diagnostic and/or therapeutic ultrasound energy to tissue within a subject. More particularly, the present invention is directed to apparatus and methods for delivering acoustic energy to target regions within a patient using a transducer device introduced into a body passage of the patient.
• In one embodiment, an apparatus for delivering acoustic energy may include a first structure carrying a first transducer, and a second structure carrying a second transducer. The first and second transducers may be disposable adjacent one another such that together they at least partially define a transducer array. In one embodiment, the first transducer may be configured to mate with the second transducer such that together they form at least a part of the transducer array. For example, a connector or other mechanism may be provided for securing the first structure to the second structure. The apparatus may include one or more additional structures, each carrying a transducer that further defines the transducer array. Each transducer of the apparatus may include a single transducer element, although preferably, each transducer includes a plurality of transducer elements. In addition, the apparatus may include a balloon, bag, or other coupling membrane that may receive the first and second structures or otherwise may surround the resulting transducer array for acoustically coupling the transducer array with surrounding tissue.
• In accordance with another aspect of the present invention, an apparatus is provided for delivering acoustic energy that includes an expandable structure carrying a plurality of transducer elements. The structure may be movable into a contracted or low profile configuration to facilitate advancing the structure into a body passage, and may be expandable to an enlarged configuration such that the plurality of transducer elements define a transducer array Optionally, the apparatus may include a tubular delivery device having a proximal end, a distal end, and a lumen extending between the proximal and distal ends. The structure may be disposed within the lumen in the contracted configuration during delivery and may be expanded to the enlarged configuration when advanced from the lumen. The apparatus may also include a balloon, bag, or other coupling membrane, similar to the previous embodiment.
• In accordance with yet another aspect of the present invention, an apparatus is provided for delivering acoustic energy to a target site adjacent a body passage that includes a first member including a proximal end, a distal having a size and shape for insertion into a body passage, and a first transducer carried on the distal end. The apparatus also includes a second member also including a proximal end, a distal having a size and shape for insertion into the body passage, and a second transducer carried on the distal end. The first and/or second members include one or more connectors for substantially securing the first and second members relative to one another such that the first and second transducers together at least partially define a transducer array.
• In accordance with still another aspect of the present invention, a method is provided for delivering acoustic energy into a target tissue region adjacent a body passage. A first member is introduced into a body passage until a first transducer carried by the first member is disposed adjacent the target tissue region. A second member is introduced into the body passage until a second transducer carried by the second member is disposed adjacent the first transducer. Acoustic energy is delivered from the first and second transducers towards the target tissue region to treat tissue therein.
• In accordance with yet another aspect of the present invention, an apparatus is provided for delivering acoustic energy to a target region adjacent a body passage that includes a tubular member including a proximal end, a distal end having a size and shape for insertion into a body passage, and a lumen extending between the proximal and distal ends, and a structure carrying a plurality of transducer elements, the structure being movable between a contracted configuration when disposed within the lumen of the tubular member, and an enlarged configuration when deployed from the lumen such that the plurality of transducer elements at least partially define a transducer array for delivering acoustic energy to a target region adjacent the body passage.
• In accordance with still another aspect of the present invention, a method is provided for delivering acoustic energy into a target tissue region adjacent a body passage. An expandable structure is introduced into a body passage while in a contracted configuration, the expandable structure carrying a plurality of transducer elements. The expandable structure is expanded towards an enlarged configuration, thereby arranging the plurality of transducer elements into an array. Acoustic energy is delivered from the plurality of transducer elements towards the target tissue region.
• Other aspects and features of the invention will be evident from reading the following detailed description of the preferred embodiments, which are intended to illustrate, not limit, the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
• The drawings illustrate the design and utility of preferred embodiments of the present invention, in which similar elements are referred to by common reference numerals. In order to better appreciate how advantages and objects of the present inventions are obtained, a more particular description of the present invention briefly described above will be rendered by reference to specific embodiments thereof, which are illustrated in the accompanying drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limiting its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings.
• FIG. 1 shows an exemplary ultrasound system including a transducer device delivering acoustic energy to a target tissue region within a patient.
• FIG. 2 is a perspective view of a first preferred embodiment of a transducer device, including first and second elongate members carrying transducer elements, that may be used in the system ofFIG. 1.
• FIG. 3 is a perspective view of the transducer device ofFIG. 2, showing the first and second elongate members mated together such that the transducer elements define a transducer array.
• FIG. 4 is a cross-sectional side view of an alternative embodiment of the transducer device ofFIGS. 2 and 3, including an expandable balloon surrounding the transducer elements.
• FIG. 5 is a perspective view of the transducer device ofFIG. 4, showing a plug for sealing an inlet of the balloon and a source of inflation fluid coupled to the plug.
• FIGS. 6 and 7 are perspective views of another embodiment of a transducer device, including an expandable structure carrying a plurality of transducer elements in enlarged and contracted configurations, respectively.
• FIG. 8 is a cross-sectional side view of the transducer device ofFIGS. 6 and 7, including an expandable balloon surrounding the expandable structure.
• FIGS. 9A-9C are cross-sectional views of a body passage, showing a method for treating tissue adjacent the body passage using a transducer device introduced into the body passage.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
• Turning to the drawings,FIG. 1 shows an exemplary embodiment of afocused ultrasound system5 including atransducer device10,drive circuitry16 coupled to thetransducer device10, and acontroller18 coupled to thedrive circuitry16. As shown, thetransducer device10 generally may be introduced into abody passage92 within apatient90 and used to deliver acoustic energy (represented by beam15) to atarget tissue region94 located adjacent thebody passage92. Theacoustic energy15 may be used to necrose, heat, or otherwise treat thetarget tissue region94, which may be a benign or malignant tumor within an organ or other tissue structure (not shown).
• Thetransducer device10 generally includes one ormore transducers12 that are coupled to thedriver16 and/orcontroller18 for generating and/or controlling the acoustic energy emitted by thetransducer12. For example, thedriver16 may generate one or more electronic drive signals, which may be controlled by thecontroller18. Thetransducer12 converts the drive signals intoacoustic energy15, which may be focused using conventional methods.
• Thecontroller18 and/ordriver16 may be separate or integral components. It will be appreciated by one skilled in the art that the operations performed by thecontroller18 and/ordriver16 may be performed by one or more controllers, processors, and/or other electronic components, including software and/or hardware components. The terms controller and control circuitry may be used herein interchangeably, and the terms driver and drive circuitry may be used herein interchangeably.
• Thedriver16, which may be an electric oscillator, may generate drive signals in the ultrasound frequency spectrum, e.g., as low as twenty kilohertz (20 kHz), and typically ranging from about half to ten Megahertz (0.5 to 10 MHz). Preferably, thedriver16 provides drive signals to thetransducer12 at radio frequencies (RF), for example, between about half to ten Megahertz (0.5-10 MHz), and more preferably between about one and two Megahertz (1.5 and 2.5 MHz). When the drive signals are provided to thetransducer12, thetransducer12 emitsacoustic energy15 from its exposed surface, as is well known to those skilled in the art.
• Thecontroller18 may control the amplitude, and therefore the intensity or power of the acoustic waves transmitted by thetransducer12. Thecontroller18 may also control a phase component of the drive signals to respective transducer elements of thetransducer12, e.g., to control a shape of afocal zone38 generated by thetransducer12 and/or to move thefocal zone38 to a desired location. For example, thecontroller18 may control the phase shift of the drive signals based upon a radial position of respective transducer elements of thetransducer12, e.g., to adjust a focal distance of the focal plane (i.e., the distance from the face of thetransducer12 to the center of the focal zone). In addition or alternatively, thecontroller18 may control the phase shift of the drive signals based upon a angular position around the face of the transducer device, e.g., to adjust a shape of the focal zone, as is well known to those skilled in the art. In addition or alternatively, thetransducer12 may be pivotable and thecontroller18 may control one or more tilt angles of thetransducer12.
• As explained above, thetransducer12 converts the drive signals into acoustic energy represented byenergy beam15. As theacoustic energy15 passes through the patient's body, theacoustic energy15 is converted to heat at the focal zone withintarget region94, thereby raising the temperature of tissue within thetarget region94. Theacoustic energy15 may be focused on thetarget region94 to raise the temperature of the tissue to necrose the tissue within thetarget region94 while minimizing damage to surrounding healthy tissue. Exemplary apparatus for measuring and/or calibrating the energy output of a transducer device are described in U.S. patent application Ser. No. 10/005,845, filed Dec. 3, 2001. The disclosure of this application and any references cited therein are expressly incorporated herein by reference.
• Turning toFIG. 2, a first embodiment of atransducer device100 is shown that includes a first structure orelongate member102 and a second structure orelongate member104. The firstelongate member102 includes aproximal end106, adistal end108, and one ormore transducer elements110 carried on thedistal end108. The secondelongate member104 also includes aproximal end112, adistal end114, and one ormore transducer elements116 carried on thedistal end114. The first and secondelongate members102,104 may be substantially rigid, semi-rigid, or substantially flexible, preferably having sufficient column strength such that the distal ends108,114 may be advanced into a body passage from the proximal ends106,112 without substantially buckling or kinking.
• As shown inFIG. 3, the first and secondelongate members102,104 may be mated together such that thetransducer elements110,116 together provide atransducer array118. Preferably, the first and secondelongate members102,104 include cooperating connectors that may removably secure them together. For example, a hook ortab120 may be provided on the firstelongate member102 that may be received in a corresponding opening or slot122 (shown in phantom) in the secondelongate member104, as shown inFIG. 2. Alternatively, other connectors or locking mechanisms may be provided, as will be appreciated by those skilled in the art. For example, a snap-fit or compression-fit mechanism, cooperating slots and/or tabs for sliding engagement, and the like (not shown) may be provided for detachably securing the first and the secondelongate members102,104 to one another.
• Each of theelongate members102,104 has a cross-sectional dimension or width that allows the distal ends108,114 to be inserted into a body passage (not shown). The body passage may be a natural passage, such as a rectal orifice, mouth, esophagus, a nasal orifice, vagina, blood vessel, and the like. Alternatively, the body passage may be a surgically-created passage, e.g., as created using an endoscopic or laparoscopic instrument (not shown). As such, the cross-sectional dimension of each of theelongate members102,104 may vary depending upon the particular application or surgical procedure. Generally, theelongate members102,104 may be inserted through an initial, relatively narrow orifice into a body passage or cavity having a larger size. Thus, the initial orifice may be the limiting factor dictating the maximum cross-sectional dimension or width of the individual elongate members.
• In one embodiment, thedistal end108,116 of each of theelongate members102,104 has a cross-sectional dimension that is sufficiently small to allow the respectivedistal end108,114 to be inserted individually through a rectal orifice (not shown). Once inserted through the rectal orifice, the rectum or colon may provide greater space, e.g., such that the distal ends108,114 may be assembled together. In this example, the width or cross-sectional dimension for the distal ends108,116 may be between about ten and seventy millimeters (10-70 mm).
• In a preferred embodiment, theelongate members102,104 are substantially symmetrical and have similar widths, as shown inFIGS. 2 and 3. In alternative embodiments, theelongate members102,104 may have different dimensions and/or may be asymmetrical relative to each other. In further alternatives, one or more additional elongate members (not shown) may be provided that include one or more transducer elements such that the transducer device may include three or more elongate members (not shown). Thus, the first and second members may be divided into two or more additional elongate members, depending upon the desired maximum cross-section of each individual elongate member, i.e., depending upon the relative size of the assembled transducer array and the orifice through which the components must pass into the body.
• Theelongate members102,104 may be made from a variety of materials, such as plastics, polymers, metals, and alloys. In the illustrated embodiment, each of theelongate members102,104 has an elongated body. However, theelongate members102,104 may have other shapes and forms so long as they are capable of providing a platform or area for carrying therespective transducer elements110,116.
• Each of thetransducer elements110,116 may be a one-piece piezoceramic element, or alternatively, a mosaic arrangement including a plurality of small piezoceramic elements. The piezoceramic element(s) may have a variety of geometric shapes, such as hexagons, triangles, squares, and the like, and may be disposed about acentral axis119 of theelongate members102,104. In a preferred embodiment, thecentral axis119 may be located on the distal ends108,114 at a junction between the first and secondelongate members102,104. More preferably, thetransducer elements110,116 are arranged on the distal ends108,114 in a substantially uniform or symmetrical configuration about thecentral axis119.
• In addition, theelongate members102,104 may include one or more leads, e.g., wires or conductive paths (not shown), extending between the proximal ends106,112 anddistal ends108,114, and coupled to thetransducer elements110,116. The proximal ends106,112 may include connectors (not shown) for connecting cables and the like to theelongate members102,104, e.g., to couple thetransducer elements110,116 to adriver16 and/or controller18 (not shown, seeFIG. 1). Thus, thedriver16 and/orcontroller18 may generate drive signals for causing thetransducer elements110 and114 to emit acoustic energy. In an alternative embodiment, each of theelongate members102,104 may be coupled to a separate driver (not shown) that is connected to a common or separate controller(s). In yet another alternative embodiment, one of theelongate members102,104 may be coupled to a driver, and the other of theelongate member102,104 may be coupled to leads in the first elongate member when theelongate members102,104 are connected to one another.
• As shown inFIG. 3, once thetransducer device100 is assembled, thetransducer elements110,116 define an assembledtransducer array118. Thetransducer array118 may have a variety of shapes and configurations. In one embodiment, thetransducer array118 may have a concave or bowl shape, such as a “spherical cap” shape, i.e., having a substantially constant radius of curvature such that thetransducer array118 has an inside surface defining a portion of a sphere.
• Alternatively, thetransducer array118 may have a substantially flat configuration (not shown), and/or may include an outer perimeter that is generally, but not necessarily, circular (not shown). Thetransducer array118 may be divided into any desired number of rings and/or sectors (not shown). In one embodiment, thetransducer array118 may have an outer diameter of between about thirty and seventy millimeters (30-70 mm), a radius of curvature between about thirty and fifty millimeters (30-50 mm), and may include between about forty and five hundred elements. For example, thetransducer array118 may be divided into between about ten and thirty (10-30) rings and about four and sixteen (4-16) sectors, although thetransducer array118 is not limited to such a configuration.
• The assembledtransducer array118 may also have other configurations, such as flat circular arrays, linear arrays, and the like, so long as it may be detachably assembled from thetransducer elements110,114 carried by multiple structures, such as theelongate members102,104. Thetransducer array118 may be arranged generally in a plane that is substantially parallel to thelongitudinal axis103 of theelongate members102,104, or the array1118 may be oriented at an angle with respect to thelongitudinal axis103. Additional information on the construction and use of transducer arrays may be found in co-pending application Ser. No. 09/884,206, filed Jun. 19, 2000. The disclosure of this application and any references cited therein are expressly incorporated herein by reference.
• Referring toFIG. 4, thetransducer device10 may also include a coupling membrane, such as an inflatable bag orballoon150. Theballoon150 includes aproximal end152, adistal end154, and an interior156 within which the first and/or secondelongate members102,104 may be disposed. Theproximal end152 of theballoon150 has anopening157 communicating with the interior156 for delivering fluid therein. Theballoon150 may be expandable from a collapsed configuration to facilitate insertion into a body passage to an expanded configuration for substantially engaging tissue surrounding the body passage when fluid158 is introduced into the interior156. Theballoon150 may be substantially inelastic, i.e., may be folded or otherwise compressed into the collapsed configuration, and may be expanded to a predetermined size as fluid is introduced into the interior156. Alternatively, theballoon150 may be elastic and/or compliant such that theballoon150 may expand to fill the available volume and may substantially conform to the shape of the wall and tissue surrounding the body passage.
• The fluid158 may be a liquid acoustic propagation medium for propagating or transmitting acoustic energy generated by thetransducer array118. Theballoon150 and/orfluid158 preferably have an acoustic impedance that corresponds substantially to the acoustic impedance of tissue. For example, theballoon150 may be made from a polymer or rubber, such as EPDM rubber, and the fluid158 may be degassed water.
• As shown inFIG. 5, thetransducer device100 may include a coupler or plug170 that may be received in theopening157 or otherwise secured to theproximal end152 of theballoon150. Theplug170 may include an adapter (not shown) for coupling theproximal end152 of theballoon150 to a source offluid171. In the illustrated embodiment, theplug170 is an annular body including anopening172 through which the proximal ends106,112 of theelongate members102,104 may be received. Theplug170, as shown, has a circular cross-sectional shape, although theplug170 may have other cross-sectional shapes, such as an elliptical shape, a rectangle shape, or other desired shapes. Theplug170 preferably has a shape for mating with theproximal end152 of theballoon150, or theplug170 and/orproximal end152 may include connector(s) for securing theplug170 to theballoon150.
• Theplug170 may include aport174 extending therethrough for delivering and/or drainingfluid158 within theballoon150. Alternatively, theplug170 may include a separate inlet port (not shown) for delivering fluid158 to theinterior156 of theballoon150, and an outlet port (also not shown) for draining fluid158 from theinterior156 of theballoon150. Thus, delivery tube(s) (not shown) may be connected to the port(s) that may be connected to a source of fluid or a source of vacuum, e.g., a syringe and the like (not shown).
• Turning toFIGS. 9A-9C, thetransducer device10 may be used to treat a target tissue region adjacent to a body passage. For example, the target tissue region may be aregion94 within aprostate96, and the body passage may be a rectum orcolon92. As explained above, thetransducer device10 may be used to treat other target tissue regions, such as benign or malignant tumors, within organs or other tissue structures, that is located adjacent a body passage, which may be a natural passage or one surgically-created to provide access.
• First, as shown inFIG. 9A, if thetransducer device10 includes aballoon150, theballoon150 may be inserted into therectum92 throughrectal orifice98. Initially, theballoon150 may be provided in a collapsed condition, e.g., disposed within a lumen of a tubular delivery device (not shown), and advanced into therectum92 through therectal orifice98. For example, a distal end of the tubular device may be inserted first into therectum92, and then theballoon150 may be inserted through the lumen of the tubular device. In addition or alternatively, theballoon150 may be carried on an introducer that may be inserted through theproximal end152 into theinterior156 of theballoon150 before theballoon150 is inserted through into therectum92. Theballoon150 may be collapsed around the introducer and then advanced into the lumen of the tubular device. Alternatively, theballoon150 carried on the introducer may be inserted directly into the rectum without the tubular device. In a further alternative, theballoon150 may be sufficiently rigid that it may be advanced through the lumen of the delivery device without an introducer. The delivery device and/or introducer may be removed from therectum92 once theballoon150 is positioned adjacent thetarget tissue region94. To facilitate their removal, fluid may be introduced into theinterior156 of theballoon150 to separate theballoon150 from the introducer.
• Next, as shown inFIG. 9B, thedistal end108 of the firstelongate member102 may be inserted through therectal orifice98 into therectum92, preferably through theproximal opening152 in theballoon150 such that thedistal end108 enters theinterior156 of theballoon150. Because of the width of thedistal end108, therectal orifice98 may be partially dilated to facilitate its insertion. However, because thedistal end108 is substantially smaller than the overall size of the assembled transducer array118 (seeFIG. 9D), risk of damaging therectal orifice98 is substantially reduced during insertion of thefirst structure102.
• Similarly, as shown inFIG. 9C, thedistal end114 of the secondelongate member104 may be inserted through therectal orifice98 into therectum92, e.g., into theinterior156 of theballoon150. Theproximal end106 of the firstelongate member102 already occupies a portion of therectal orifice98, and so thedistal end114 of the secondelongate member104 must be introduced adjacent to the firstelongate member102. The relative configuration, e.g., widths or cross-sectional dimensions, of the distal ends108,114 may be sized to dictate the order in which theelongate members102,104 are inserted into therectum92, as will be appreciated by those skilled in the art. Generally, because thedistal end114 of the secondelongate member104 also has a cross-section sufficiently small to allow insertion of thedistal end114 through arectal orifice98, injury to therectal orifice98 is substantially reduced.
• Turning toFIG. 9D, once the distal ends108,114 have been inserted into therectum92, the distal ends108,114 and/or theballoon150 may be positioned to orient thetransducer elements110,116 relative to thetarget region94. In an alternative embodiment, theballoon150 may be provided around thedistal end108 of the firstelongate member102 initially collapsed, and introduced simultaneously with the firstelongate member102.
• The first and secondelongate members102,104 may be secured together, e.g., using the cooperatinghook120 and slot122 (not shown, seeFIG. 2), to ensure that thetransducer elements110,116 are arranged adjacent to one another to define the assembledtransducer array118. Alternatively, the firstelongate member102 may include an elongate track or rail (not shown) along which the secondelongate member104 may be advanced when inserted into therectum92 to dispose the transducer element(s)116 adjacent the transducer element(s)110. Thus, the resultingtransducer array118 may have an overall cross-sectional dimension that may be maximized relative to the narrowrectal orifice98, i.e., that exceeds the size of single-piece transducer array that may be inserted through therectal orifice98. In a further alternative, theelongate members102,104 may remain free from one another, i.e., not connected, while thetransducer elements110,116 may disposed adjacent one another. In this embodiment, one or bothelongate members102,104 may carry a tracking device for monitoring their location relative to one another and/or thetarget tissue region94.
• If thetransducer device10 includes theballoon150, the plug170 (not shown, seeFIG. 5) may be connected to theproximal end152 of theballoon150, and a source of fluid171 (also not shown, seeFIG. 5) may be coupled to theplug170 for delivering fluid into theballoon150. Theplug170 may be advanced over the proximal ends106,112 of theelongate members102,104, i.e., with the proximal ends106,112 passing through theopening172. Theplug170 may slidably and sealingly engage theelongate members102,104 to prevent substantial leakage of fluid through theopening172. Optionally, theplug170 may sufficiently stabilize the distal ends108,114 of theelongate members102,104 that no other connectors or locking mechanism may be necessary.
• As shown inFIG. 9D, fluid may be introduced into theinterior156 of theballoon150 to expand theballoon150 until it substantially engages the wall of therectum92. Preferably, theballoon150 substantially conforms to the shape of the wall of therectum92 to minimize gaps and enhance acoustically coupling thetransducer array118 to tissue surrounding therectum92. After a desired amount of fluid has been delivered, theport174 of the plug170 (not shown) may be closed to prevent fluid from escaping from theinterior156 of theballoon150. Alternatively, if thetransducer device10 does not include theplug170, tubing (not shown) may be inserted into theproximal end152 of theballoon150 that is coupled to a source of fluid for inflating theballoon150, whereupon theproximal end152 of theballoon150 may be sealed, e.g., using a clip, cap, and the like (not shown).
• Thetransducer array118 may be oriented towards thetarget tissue region94, i.e., within theprostate96, which may require the proximal ends106,112 of theelongate members102,104 to be positioned or manipulated further. Positioning thetransducer array118 may be monitored using imaging techniques known in the art, such as fluoroscopy and ultrasonic imaging. Radiopaque markers (not shown) may be provided on one or both of the distal ends108,114 of theelongate members102,104 to assist monitoring and positioning thetransducer array118.
• Once thetransducer118 is properly oriented, thetransducer array118 is then activated to deliver acoustic energy to thetarget tissue region94. Thedriver16 and/or controller18 (not shown, seeFIG. 1) may control the acoustic energy emitted by thetransducer array118 to focus and/or adjust the intensity of the acoustic energy to heat thetarget tissue region94, while minimizing heating tissue surrounding thetarget tissue region94. The fluid-filledballoon150 may enhance acoustic coupling of thetransducer array118 with the intervening tissue between therectum92 and thetarget tissue region94, as explained above.
• If the first and secondelongate members102,104 are not connected to one another, they may be manipulated individually or together. In addition, eachtransducer element110,116 may be tested, e.g., activated individually using relatively low power, to confirm that eachtransducer element110,116 is oriented towards thetarget tissue region94 before activating the entire transducer array to treat thetarget tissue region94. If the focal zone of eachtransducer element110,116 is not properly focused at thetarget tissue region94, the focal zone may be adjusted physically and/or electronically, as will be appreciated by those skilled in the art. Thus, the transducer elements may be provided at different positions and/or angles relative to one another before the transducer array is activated to treat thetarget tissue region94. In further alternatives, transducers may be introduced into different body passages and positioned and/or focused towards a target tissue region adjacent to each of the transducers.
• After a desired amount of acoustic energy has been delivered, e.g., to ablate or otherwise treat thetarget tissue region94, optionally, thetransducer device10 may be moved to another location, electronically steered, and/or otherwise repositioned within therectum92, e.g., with theelongate members102,104 and/orballoon150 remaining assembled together. Additional tissue regions may then be treated. Alternatively or finally, thetransducer device10 may be removed from therectum92 via therectal orifice98. Generally, this involves deflating theballoon150, disconnecting theelongate members102,104 (if secured together), and removing theelongate members102,104 one at a time. Theballoon150 may be removed with the final elongate member or after all of the elongate members are removed from therectum92.
• Turning toFIGS. 6-8, another embodiment of atransducer device200 is shown that includes atubular delivery device202, and anelongate member220 carrying a plurality oftransducer elements206. Thetubular delivery device202 has aproximal end210, adistal end212, and alumen214 extending between the proximal anddistal ends210,212. Theelongate member220 includes aproximal end222, adistal end223, and anexpandable structure224 on thedistal end223 that carries thetransducer elements206. Optionally, thetransducer device200 may also include a balloon, bag, or other coupling membrane251 (shown inFIG. 8) and a coupler or plug (not shown) for sealing theballoon251 and/or coupling a source of fluid to theballoon251 medium, similar to the embodiments described previously with reference toFIGS. 4 and 5
• Theexpandable structure224 may be bent, folded, or otherwise collapsed into a low profile or contracted configuration (shown inFIG. 7), e.g., to facilitate advancing or retracting theexpandable structure224 out of and into thelumen214 of thedelivery device202. Thestructure224 is also expandable to an enlarged configured (shown inFIG. 6) for arranging thetransducer elements206 to define atransducer array220. Theelongate member222 may be a substantially rigid, semi-rigid, or flexible wire or other body and theexpandable structure224 may be attached to or otherwise carried by thedistal end223.
• The expandable structure234 may be made from an elastic material, such as plastic and/or metal, e.g., biased to expand towards the enlarged configuration, yet elastically deformable towards the contracted configuration. In a preferred embodiment, theexpandable structure224 may be formed from a super-elastic alloys, such as a nickel/titanium (“Nitinol”) alloy. Other materials known in the art may also be used so long as theexpandable structure224 is capable of performing the functions described herein.
• Theexpandable structure224,elongate member220, and/ordelivery device202 may include one or more radiopaque markers (not shown) to assisting monitoring thetransducer device200 as it being manipulated within a body passage of a patient. For example, theexpandable structure224 may be coated or mixed with radiopaque materials, such as tantalum, gold, tungsten or platinum, barium sulfate, bismuth oxide, bismuth subcarbonate, and the like. Alternatively, continuous or discrete radiopaque markers may be affixed to theexpandable structure224. In a further alternative, one or more of the components may include micro-coil trackers that may be compatible for monitoring using MRI.
• In the exemplary embodiment shown inFIGS. 6 and 7, theexpandable structure224 may include a plurality ofpetals225, each carrying one ormore transducer elements206. Thepetals225 may be connected to thedistal end223 of theelongate member220 by respective hinged regions, which may be living hinges, pinned hinges, and the like. Thepetals224 may be biased to assume the enlarged configuration automatically when deployed from thelumen214 of thedelivery device202, but may be compressed into the contracted configuration simply by retracting thedistal end223 of theelongate member220 into thelumen214. Alternatively, thepetals225 may be coupled to wires or other elements (not shown) that may be manipulated to expand and/or contract thepetal s225. The number ofpetals224 may vary, e.g., four, five, six (as shown), or more, and should not limited to the illustrated embodiment.
• Each of thetransducer elements206 may include a single piezoceramic element or preferably may include a mosaic arrangement including a plurality of small piezoceramic elements. The piezoceramic elements may have a variety of geometric shapes, such as hexagons, triangles, squares, and the like.
• Similar to the previous embodiments, adriver16 and/or driver18 (not shown, seeFIG. 1) may be coupled to thetransducer elements206, e.g., by leads (not shown) on or in theelongate member220. Thetransducer elements206 may be driven with respective drive signals for focusing acoustic energy transmitted by thetransducer elements206 towards a focal zone within a target region. Phase, amplitude, and/or other parameters of the drive signals may be controlled to provide a desired size, shape, and/or location for the focal zone, similar to the previous embodiment.
• In the enlarged configuration shown inFIG. 6, the resultingtransducer array226 may have a variety of shapes and configurations. In one embodiment, thetransducer array226 may have a concave or bowl shape, such as a “spherical cap” shape, i.e., having a substantially constant radius of curvature such that thetransducer array226 has an inside surface defining a portion of a sphere. Alternatively, thetransducer array226 may have a substantially flat configuration (not shown), and/or may include an outer perimeter that is generally, but not necessarily, circular (not shown). Thetransducer array226 may be divided into any desired number of rings and/or sectors (not shown), all similar to the previous embodiment.
• Those skilled in the art will appreciate that theexpandable structure224 may include other elements that may be collapsed and/or expanded. For example, in an alternative embodiment, the expandable structure may include an inflatable balloon (not shown) carrying a plurality of transducer elements. As the balloon is inflated, the transducer elements may assume a configuration of a transducer array, similar to the previous embodiment. In a further alternative embodiment, thestructure204 may include other hinged elements that are connected to otherwise carried by thedistal end223 of theelongate member220.
• As shown inFIG. 8, theexpandable structure224 is expanded towards the enlarged configuration within aballoon251. Thetransducer device200 also may include atubular element250, including aproximal end252, adistal end254, and alumen256 extending between the proximal anddistal ends252,254. Thetubular element250 may be positioned within thelumen214 of thedelivery device202, and surround theelongate member220.
• Theballoon251 may be coupled to thedistal end254 of thetubular element250 such that an interior258 of theballoon251 communicates with thelumen256 of thetubular element250. Theballoon251 is expandable, similar to the previous embodiment, towards an expanded configuration that is larger than theexpandable structure224 in its enlarged configuration, e.g., to substantially engage a wall of a body passage within which thetransducer device200 is introduced. Theballoon251 may a collapsed configuration or low profile when deflated and disposed within thelumen214 of thedelivery device202, and may be inflated towards the expanded configuration. Theballoon251 is preferably made from a material including an acoustic impedance that is substantially similar to the acoustic impedance of body tissue, as discussed previously with reference to theballoon150.
• When using theultrasound device200 to treat a prostate, thetubular delivery device202 is first inserted into a rectum through a rectal orifice (not shown). Theexpandable structure224 may be placed within thelumen214 of thedelivery device202 before or after thetubular delivery device202 is inserted into the rectum. If thetransducer device200 includes aballoon251, theballoon251, together with theelongate member220, may be introduced into thelumen214 of thedelivery device202 before or after thedelivery device202 is inserted into the rectum.
• After thedistal end212 of thedelivery device202 has been advanced sufficiently, the distal end of theelongate member220 may be advanced from the delivery device to deploy theexpandable structure224 within the rectum. Theexpandable structure204 may be manipulated within the rectum until thepetals225 are fully exposed, whereupon thepetals225 may automatically expand or may be actuated to expand towards the enlarged configuration. In the enlarged configuration, thetransducer elements206 generally assume atransducer array226, which may then be oriented towards a target tissue region (not shown).
• If thetransducer device200 includes aballoon251, theballoon251 maybe advanced into the rectum before or simultaneously with theelongate member220. Other methods known in the art may also be used to deploy theballoon251. For example, a plunger or guidewire (not shown) may be used to deliver theballoon251 into the rectum.
• After theballoon251 and theexpandable structure204 have been deployed and desirably placed within the rectum, fluid may be delivered into theinterior258 of theballoon251 to expand theballoon251 until it substantially engages the surrounding wall of the rectum. Fluid may be delivered directly into the openproximal end252 of thetubular element250 and into theinterior258 of theballoon251. Alternatively, a coupler or plug (not shown), similar to that described previously with reference toFIG. 5, may be used to seal theballoon251 and/or couple theballoon251 to a source of fluid.
• Once thetransducer array226 is properly positioned and/or oriented, drive signals may be delivered to thetransducer elements206 to focus acoustic energy to the target site, similar to the previous embodiment. After sufficient ultrasonic energy has been delivered, the expandable structure224 (and balloon251) may be collapsed, repositioned, expanded and activated to focus acoustic energy at a an other target site. Once sufficient tissue is treated, the expandable structure224 (and balloon251) may be withdrawn into thelumen214 of thedelivery device202 and/or otherwise removed from the rectum.
• Although the above described embodiments have been described with reference to treating a prostate, it should be understood by those skilled in the art that the apparatus and methods described herein may also be used to treat other areas of a body. In addition, the transducer devices described herein may be used in cooperation with external transducer arrays, such as those described in the references incorporated by reference elsewhere herein. Thus, a hybrid procedure, in which acoustic energy is delivered to a target site using two transducers, one internal and one external, simultaneously. Alternatively, multiple transducer devices, such as those described herein, may be inserted into different body passages for delivering acoustic energy to a target site in cooperation within one another. For example, in a single treatment, a first transducer device may be introduced into a rectum, and a second transducer device may be introduced into a vagina of a female patient to treat tissue adjacent the rectum and the vagina. Furthermore, besides treating tissue, the transducer devices described herein may also be for obtaining acoustic images of tissue regions within a patient.
• Thus, although several preferred embodiments have been shown and described, it would be apparent to those skilled in the art that many changes and modifications may be made thereunto without departing from the scope of the invention, which is defined by the following claims and their equivalents.

Claims (1)

1. An apparatus for delivering acoustic energy to a target site adjacent a body passage, comprising:

a first member comprising a proximal end, a distal end having a size and shape for insertion into a body passage, and a first transducer carried on the distal end; and

a second member comprising a proximal end, a distal having a size and shape for insertion into the body passage, and a second transducer carried on the distal end, the first and second transducers detachably coupled to each other to at least partially form a transducer array for delivering acoustic energy to a target site adjacent the body passage.

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