# Patent

## Title
Method and system for treating stretch marks

## Abstract

Methods and systems for treating stretch marks through deep tissue tightening with ultrasound are provided. An exemplary method and system comprise a therapeutic ultrasound system configured for providing ultrasound treatment to a shallow tissue region, such as a region comprising an epidermis, a dermis and a deep dermis. In accordance with various exemplary embodiments, a therapeutic ultrasound system can be configured to achieve depth from 0 mm to 1 cm with a conformal selective deposition of ultrasound energy without damaging an intervening tissue in the range of frequencies from 2 to 50 MHz. In addition, a therapeutic ultrasound can also be configured in combination with ultrasound imaging or imaging/monitoring capabilities, either separately configured with imaging, therapy and monitoring systems or any level of integration thereof.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This invention claims priority to and the benefit of U.S. Provisional No. 60/617,338, filed on Oct. 7, 2004, which is hereby incorporated by reference.


FIELD OF INVENTION
The present invention relates to ultrasound treatment systems, and in particular to a method and system for treating stretch marks.
BACKGROUND OF INVENTION
Stretch marks, or striae disease, are the disfiguring permanent scars left in skin usually caused by excessive stretching such as during and after rapid weight gain or pregnancy. These marks occur in 50-90% of all pregnant women, and usually appear in the later half of pregnancy as bright red or purplish lines. While the majority will be on the lower abdomen they can also be found on the thighs, hips, buttocks, breasts and arms of women. During the postpartum period, the reddish lines typically turn into shallow silver scars.
Hydration of the skin via lotions and creams may help reduce the creation of stretch marks and their effects in some cases, but cannot prevent them in women prone to the condition. Studies investigated the effect of applying 0.1 percent tretinoin (retinoic acid or Retin-A) cream to stretch marks (S Kang et al. Topical tretinoin (retinoic acid) improves early stretch marks. Arch Dermatol 1996; 132:519-526.). Both the length and width of the marks were diminished but side effects include dry and itchy skin and moderate to severe erythema. This treatment works best when applied during the first few days postpartum; however, its effects on breastfeeding are not known. It is toxic and teratogenic, and should never be used during pregnancy.
Postpartum light treatment may be helpful to diminish the appearance of stretch marks. For temporary cosmetic relief, ultraviolet light (UVA) exposure may be used to tan the lighter skin areas represented by stretch marks. In the limited cases where stretch marks are darker than the surrounding skin, intense pulsed light may be used to remove pigment. Pulsed dye lasers are also used.
Patterns of thermal ablation to epidermis and/or dermis and/or fibrous fascia are effective for treatment of various skin conditions. Recently, “fractional photothermolysis” using mid-infrared lasers to produce a microscopic array of thermal injury zones that include both epidermis and dermis was reported to be effective and well-tolerated for treatment of skin remodeling. A primary advantage of fractional photothermolysis is that each zone of thermal injury is smaller than can be easily seen with the unaided eye, and surrounded by a zone of healthy tissue that initiates a rapid healing response. Repeat treatments, which are well tolerated, can be performed until a desired result is obtained. However, similar to any light based treatment, fractional photothermolysis poses the disadvantage that it is intrinsically limited to regions of approximately the upper 1 millimeter of skin, because light that propagates more than about 1 mm through skin has been multiply scattered, and can no longer be focused or delivered effectively to the treatment area. Stretch marks involve both superficial and deep layers of the dermis, as well as fibrous fascia. Therefore it is imperative to treat not only near the surface of skin, but all the way down to the deep dermis and fibrous fascia.
SUMMARY OF INVENTION
A method and system for ultrasound treatment of stretch marks are provided. An exemplary method and system are configured for treating stretch marks with therapy only, therapy and monitoring, imaging and therapy, or therapy, imaging, and monitoring using focused, unfocused, or defocused ultrasound at various spatial and temporal energy settings for targeted treatment of stretch marks and surrounding tissues.
In accordance with one embodiment of the present invention, a method and system are configured to produce regions of ablation within a treatment zone in spatially defined patterns, rather than heating and destroying the entire volume of the target layer of tissue. In accordance another exemplary embodiment of the present invention, a method and system can be configured to specifically aim such regions of ablation within a treatment zone, to occur at the same location as the stretch marks.



BRIEF DESCRIPTION OF THE DRAWINGS
The subject matter of the invention is particularly pointed out in the concluding portion of the specification. The invention, however, both as to organization and method of operation, may best be understood by reference to the following description taken in conjunction with the accompanying drawing figures, in which like parts may be referred to by like numerals:
FIG. 1 illustrates a block diagram of an exemplary ultrasound treatment system for treating stretch marks in accordance with an exemplary embodiment of the present invention;
FIGS. 2A-2C illustrate a cross sectional diagrams of exemplary probe systems in accordance with exemplary embodiments of the present invention;
FIGS. 3A and 3B illustrate block diagrams of an exemplary control system in accordance with exemplary embodiments of the present invention;
FIGS. 4A and 4B illustrate block diagrams of an exemplary probe system in accordance with exemplary embodiments of the present invention;
FIG. 5 illustrates a cross-sectional diagram of an exemplary transducer in accordance with an exemplary embodiment of the present invention;
FIGS. 6A and 6B illustrate cross-sectional diagrams of an exemplary transducer in accordance with exemplary embodiments of the present invention;
FIG. 7 illustrates exemplary transducer configurations for ultrasound treatment in accordance with various exemplary embodiments of the present invention;
FIGS. 8A and 8B illustrate cross-sectional diagrams of an exemplary transducer in accordance with another exemplary embodiment of the present invention;
FIG. 9 illustrates an exemplary transducer configured as a two-dimensional array for ultrasound treatment in accordance with an exemplary embodiment of the present invention;
FIGS. 10A-10F illustrate cross-sectional diagrams of exemplary transducers in accordance with other exemplary embodiments of the present invention;
FIG. 11 illustrates a schematic diagram of an acoustic coupling and cooling system in accordance with an exemplary embodiment of the present invention;
FIG. 12 illustrates a block diagram of a treatment system comprising an ultrasound treatment subsystem combined with additional subsystems and methods of treatment monitoring and/or treatment imaging as well as a secondary treatment subsystem in accordance with an exemplary embodiment of the present invention; and
FIGS. 13A and 13B illustrate schematic diagrams of treatment regions in accordance with exemplary embodiments of the present invention.



DETAILED DESCRIPTION
The present invention may be described herein in terms of various functional components and processing steps. It should be appreciated that such components and steps may be realized by any number of hardware components configured to perform the specified functions. For example, the present invention may employ various medical treatment devices, visual imaging and display devices, input terminals and the like, which may carry out a variety of functions under the control of one or more control systems or other control devices. In addition, the present invention may be practiced in any number of medical contexts and that the exemplary embodiments relating to a method and system for treating stretch marks as described herein are merely indicative of exemplary applications for the invention. For example, the principles, features and methods discussed may be applied to any medical application. Further, various aspects of the present invention may be suitably applied to other applications.
In accordance with various aspects of the present invention, a method and system for treating stretch marks are provided. For example, in accordance with an exemplary embodiment, with reference to FIG. 1, an exemplary treatment system 100 configured to treat a region of interest 106 comprises a control system 102, an imaging/therapy probe with acoustic coupling 104, and a display system 108. Control system 102 and display system 108 can comprise various configurations for controlling probe 102 and overall system 100 functionality, such as, for example, a microprocessor with software and a plurality of input/output devices, system and devices for controlling electronic and/or mechanical scanning and/or multiplexing of transducers, a system for power delivery, systems for monitoring, systems for sensing the spatial position of the probe and/or transducers, and/or systems for handling user input and recording treatment results, among others. Imaging/therapy probe 104 can comprise various probe and/or transducer configurations. For example, probe 104 can be configured for a combined dual-mode imaging/therapy transducer, coupled or co-housed imaging/therapy transducers, or simply a separate therapy probe and an imaging probe.
Stretch marks reflect the separation of collagen in the dermis of the skin and damage to other tissue such as fibrous fascia and epidermis. Continuous stretching of tissue to its elastic limit and beyond causes damage to skin and its structure. In accordance with an exemplary embodiment, treatment system 100 is configured for treating the structures within the epidermis, dermis, deep dermis, and/or fibrous fascia, which include the superficial fascia, deep fascia, and/or fascia lata, by imaging of region of interest 106 for localization of the treatment area and/or surrounding structures; delivering of ultrasound energy at a depth, distribution, timing, and/or energy level to achieve the desired therapeutic effect; and monitoring the treatment area before, during, and/or after therapy to plan and assess the results and/or provide feedback.
As to the treatment of stretch marks, connective tissue can be permanently tightened by thermal treatment to temperatures about 60 degrees C. which causes tissue to shrink immediately by approximately 30% in length. Shrinkage of tissue results in tightening desired for correction of stretch marks. Treating through localized heating of regions of stretch marks to temperatures of about 60-90° C., without significant damage to overlying, underlying, or surrounding tissue, as well as the precise delivery of therapeutic energy to stretch marks and obtaining feedback from the region of interest before, during, and after treatment can be suitably accomplished through treatment system 100. Subsequent tightening of tissue in ROI 106 results in minimization of stretch marks in the targeted region in ROI 106 and improved appearance of the overlaying superficial layers of the skin.
To further illustrate an exemplary method and system 200, with reference to FIG. 2A-2C. An exemplary method and system are configured with reference to FIG. 2A for first, imaging 222 and display 224 of the region of interest 202 for localization of the treatment area and surrounding structures, second, delivery of focused, unfocused, or defocused ultrasound energy 220 at a depth, distribution, timing, and energy level to achieve the desired therapeutic effect of thermal ablation to treat stretch mark 232, and third to monitor the treatment area and surrounding structures before, during, and after therapy to plan and assess the results and/or provide feedback to control system 206 and operator. Exemplary probe 204 and/or transducers can be mechanically and/or electronically scanned 226 to place treatment zones over an extended area, and the treatment depth 220 can be adjusted between a range of approximately 0 to 10 mm, or the maximum depth of the stretch marks or deep dermis.
Exemplary transducer probe 204 can be configured to be suitably controlled and/or operated in various manners. For example, transducer probe 204 may be configured for use within an ultrasound treatment system, an ultrasound imaging system, an ultrasound monitoring system, and/or any combination of an ultrasound treatment, imaging and/or monitoring system including motion control subsystems.
Control system 206 can be configured with one or more subsystems, processors, input devices, displays and/or the like. Display 208 may be configured to image and/or monitor ROI 202 and/or any particular sub-region within ROI 202. Display 208 can be configured for two-dimensional, three-dimensional, real-time, analog, digital and/or any other type of imaging. Exemplary embodiments of both control system 206 and display 208 are described in greater detail herein.
Region of tissue 202 can comprise a superficial layer, such as, for example the epidermis and/or dermis, subcutaneous fat, and/or muscle. Exemplary transducer system 200, can be configured to provide cross-sectional two-dimensional imaging 222 of ROI 202, displayed as an image 224, with a controlled thermal lesion 220.
Exemplary ultrasound transducer probe 204 can be configured in various manners to provide various functions. For example, an ultrasound therapy transducer system can be configured for spatial control and/or temporal control by changing the position of transducer, its drive frequency, focal depth, drive amplitude, and timing of the exemplary transducer. In accordance with various exemplary embodiments, transducer probe 204 can be configured for spatial control, such as by changing the distance from transducer probe 204 to a reflecting surface, or changing the angles of energy focused or unfocused to tissue regions 202 and/or 220, and/or configured for temporal control, such as by controlling changes in the frequency, drive amplitude and timing of transducer probe 204 through control system 206. As a result, changes in the location of the treatment region, the shape and size and/or volume of the spot or region of interest, as well as the thermal conditions, can be dynamically controlled versus time.
In addition to the spatial control, control system 206 and/or transducer probe 204 can also be configured for temporal control, such as through adjustment and optimization of drive amplitude levels, frequency/waveform selections, and timing sequences and other energy drive characteristics to control the treatment of tissue. The spatial and/or temporal control can also be facilitated through open-loop and closed-loop feedback arrangements, such as through the monitoring of various positional and temporal characteristics.
In order to deliver energy to ROI 202, transducer probe 204 and/or any other transducers can be mechanically and/or electronically scanned 226 to place treatment zones over an extended area. In one embodiment, a treatment depth 220 can be adjusted between a range of approximately 0 to 10 mm, or the maximum depth of the stretch marks or deep dermis. By delivering energy, transducer probe 204 may be driven at a selected frequency, a phased array may be driven with certain temporal and/or spatial distributions, a transducer may be configured with one or more transduction elements to provide focused, defocused and/or planar energy, and/or the transducer may be configured and/or driven in any other ways hereinafter devised. Various embodiments of transducer probe 204 are described in greater detail herein.
In one embodiment, imaging 222 component can comprise a display 224 of ROI 202 to facilitate localization of the treatment area and surrounding structures. Energy 220 may be delivered to ROI 202 using transducer probe 204 configured to deliver focused, unfocused, and/or defocused ultrasound energy 220 at one or more treatment parameters. Various configurations of transducer probe 204 are disclosed herein. As used herein, the phrase “treatment parameters” includes, for example, a depth, distribution, timing, and/or energy level used to achieve a desired therapeutic effect of thermal ablation to treat stretch mark 232.
Monitoring can be achieved using one or more monitoring subsystems to monitor the treatment area and/or surrounding structures before, during, and/or after therapy. These monitoring subsystems include control system 206 and control system 206 subcomponents (described herein). Monitoring can also be used to plan and assess the results and/or provide feedback to control system 206 and/or the user. As used herein, the term user may include a person, employee, doctor, nurse, and/or technician, utilizing any hardware and/or software of other control systems.
In accordance with another aspect of the present invention, with reference to FIG. 2B, an exemplary monitoring method may monitor the temperature profile or other tissue parameters of the region of interest 202 and/or treatment zone 220, such as attenuation, speed of sound, or mechanical properties such as stiffness and strain, and suitably adjust the spatial and/or temporal characteristics and energy levels of the ultrasound therapy transducer. The results of such monitoring methods may be indicated on display 208 by means of one-, two-, or three-dimensional images of monitoring results 250, or may be as simple as success or fail type indicator 252, or combinations thereof. Additional treatment monitoring methods may be based on one or more of temperature, video, profilometry, and/or stiffness or strain gauges or any other suitable sensing method.
In accordance with another exemplary embodiment, with reference to FIG. 2C, an expanded treatment region of interest 252 includes a combination of tissues, such as subcutaneous fat/adipose tissue 216 and muscle 218, among others. A multiple of such tissues may be treated including stretch marks in combination with at least one of epidermis 212, dermis 214, adipose tissue 216, muscular fascia, muscle 218, hair, glands, and blood vessels within dermis 214, or other tissue of interest. For example, treatment 220 of stretch mark may be performed in combination with treatment of subcutaneous fat 216 by suitable adjustment of the treatment parameters and or transducers in probe 204.
As previously described, control systems 102 and 206 may be configured in various manners with various subsystems and subcomponents. With reference to FIGS. 3A and 3B, in accordance with exemplary embodiments, an exemplary control system 300 can be configured for coordination and control of the entire therapeutic treatment process in accordance with the adjustable settings made by a therapeutic treatment system user. For example, control system 300 can suitably comprise power source components 302, sensing and monitoring components 304, cooling and coupling controls 306, and/or processing and control logic components 308. Control system 300 can be configured and optimized in a variety of ways with more or less subsystems and components to implement the therapeutic system for treating stretch marks, and the embodiment in FIGS. 3A and 3B are merely for illustration purposes.
For example, for power sourcing components 302, control system 300 can comprise one or more direct current (DC) power supplies 303 configured to provide electrical energy for entire control system 300, including power required by a transducer electronic amplifier/driver 312. A DC current sense device 305 can also be provided to confirm the level of power going into amplifiers/drivers 312 for safety and monitoring purposes.
Amplifiers/drivers 312 can comprise multi-channel or single channel power amplifiers and/or drivers. In accordance with an exemplary embodiment for transducer array configurations, amplifiers/drivers 312 can also be configured with a beamformer to facilitate array focusing. An exemplary beamformer can be electrically excited by an oscillator/digitally controlled waveform synthesizer 310 with related switching logic.
The power sourcing components can also include various filtering configurations 314. For example, switchable harmonic filters and/or matching may be used at the output of amplifier/driver 312 to increase the drive efficiency and effectiveness. Power detection components 316 may also be included to confirm appropriate operation and calibration. For example, electric power and other energy detection components 316 may be used to monitor the amount of power going to an exemplary probe system.
Various sensing and monitoring components 304 may also be suitably implemented within control system 300. For example, in accordance with an exemplary embodiment, monitoring, sensing and interface control components 324 may be configured to operate with various motion detection systems implemented within transducer probe 104 to receive and process information such as acoustic or other spatial and temporal information from a region of interest. Sensing and monitoring components can also include various controls, interfacing and switches 309 and/or power detectors 316. Such sensing and monitoring components 304 can facilitate open-loop and/or closed-loop feedback systems within treatment system 100.
For example, in such an open-loop system, a system user can suitably monitor the imaging and or other spatial or temporal parameters and then adjust or modify same to accomplish a particular treatment objective. Instead of, or in combination with open-loop feedback configurations, an exemplary treatment system can comprise a closed-loop feedback system, wherein images and/or spatial/temporal parameters can be suitably monitored within monitoring component to generate signals.
During operation of exemplary treatment system 100, a lesion configuration of a selected size, shape, orientation is determined. Based on that lesion configuration, one or more spatial parameters are selected, along with suitable temporal parameters, the combination of which yields the desired conformal lesion. Operation of the transducer can then be initiated to provide the conformal lesion or lesions. Open and/or closed-loop feedback systems can also be implemented to monitor the spatial and/or temporal characteristics, and/or other tissue parameter monitoring, to further control the conformal lesions.
Cooling/coupling control systems 306 may be provided to remove waste heat from exemplary probe 104, provide a controlled temperature at the superficial tissue interface and deeper into tissue, and/or provide acoustic coupling from transducer probe 104 to region-of-interest 106. Such cooling/coupling control systems 306 can also be configured to operate in both open-loop and/or closed-loop feedback arrangements with various coupling and feedback components.
Processing and control logic components 308 can comprise various system processors and digital control logic 307, such as one or more of microcontrollers, microprocessors, field-programmable gate arrays (FPGAs), computer boards, and associated components, including firmware and control software 326, which interfaces to user controls and interfacing circuits as well as input/output circuits and systems for communications, displays, interfacing, storage, documentation, and other useful functions. System software and firmware 326 controls all initialization, timing, level setting, monitoring, safety monitoring, and all other system functions required to accomplish user-defined treatment objectives. Further, various control switches 308 can also be suitably configured to control operation.
An exemplary transducer probe 104 can also be configured in various manners and comprise a number of reusable and/or disposable components and parts in various embodiments to facilitate its operation. For example, transducer probe 104 can be configured within any type of transducer probe housing or arrangement for facilitating the coupling of transducer to a tissue interface, with such housing comprising various shapes, contours and configurations depending on the particular treatment application. For example, in accordance with an exemplary embodiment, transducer probe 104 can be depressed against a tissue interface whereby blood perfusion is partially and/or wholly cut-off, and tissue flattened in superficial treatment region-of-interest 106. Transducer probe 104 can comprise any type of matching, such as for example, electric matching, which may be electrically switchable; multiplexer circuits and/or aperture/element selection circuits; and/or probe identification devices, to certify probe handle, electric matching, transducer usage history and calibration, such as one or more serial EEPROM (memories). Transducer probe 104 may also comprise cables and connectors; motion mechanisms, motion sensors and encoders; thermal monitoring sensors; and/or user control and status related switches, and indicators such as LEDs. For example, a motion mechanism in probe 104 may be used to controllably create multiple lesions, or sensing of probe motion itself may be used to controllably create multiple lesions and/or stop creation of lesions, e.g. for safety reasons if probe 104 is suddenly jerked or is dropped. In addition, an external motion encoder arm may be used to hold the probe during use, whereby the spatial position and attitude of probe 104 is sent to the control system to help controllably create lesions. Furthermore, other sensing functionality such as profilometers or other imaging modalities may be integrated into the probe in accordance with various exemplary embodiments.
With reference to FIGS. 4A and 4B, in accordance with an exemplary embodiment, a transducer probe 400 can comprise a control interface 402, a transducer 404, coupling components 406, and monitoring/sensing components 408, and/or motion mechanism 410. However, transducer probe 400 can be configured and optimized in a variety of ways with more or less parts and components to provide ultrasound energy for treating stretch marks, and the embodiment in FIGS. 4A and 4B are merely for illustration purposes.
In accordance with an exemplary embodiment of the present invention, transducer probe 400 is configured to deliver energy over varying temporal and/or spatial distributions in order to provide energy effects and initiate responses in a region of interest. These effects can include, for example, thermal, cavitational, hydrodynamic, and resonance induced tissue effects. For example, exemplary transducer probe 400 can be operated under one or more frequency ranges to provide two or more energy effects and initiate one or more responses in the region of interest. In addition, transducer probe 400 can also be configured to deliver planar, defocused and/or focused energy to a region of interest to provide two or more energy effects and to initiate one or more responses. These responses can include, for example, diathermy, hemostasis, revascularization, angiogenesis, growth of interconnective tissue, tissue reformation, ablation of existing tissue, protein synthesis and/or enhanced cell permeability. These and various other exemplary embodiments for such combined ultrasound treatment, effects and responses are more fully set forth in U.S. patent application Ser. No. 10/950,112, entitled “METHOD AND SYSTEM FOR COMBINED ULTRASOUND TREATMENT,” Filed Sep. 24, 2004 and incorporated herein by reference.
Control interface 402 is configured for interfacing with control system 300 to facilitate control of transducer probe 400. Control interface components 402 can comprise multiplexer/aperture select 424, switchable electric matching networks 426, serial EEPROMs and/or other processing components and matching and probe usage information 430 and interface connectors 432.
Coupling components 406 can comprise various devices to facilitate coupling of transducer probe 400 to a region of interest. For example, coupling components 406 can comprise cooling and acoustic coupling system 420 configured for acoustic coupling of ultrasound energy and signals. Acoustic cooling/coupling system 420 with possible connections such as manifolds may be utilized to couple sound into the region-of-interest, control temperature at the interface and deeper into tissue, provide liquid-filled lens focusing, and/or to remove transducer waste heat. Coupling system 420 may facilitate such coupling through use of various coupling mediums, including air and other gases, water and other fluids, gels, solids, and/or any combination thereof, or any other medium that allows for signals to be transmitted between transducer active elements 412 and a region of interest. In addition to providing a coupling function, in accordance with an exemplary embodiment, coupling system 420 can also be configured for providing temperature control during the treatment application. For example, coupling system 420 can be configured for controlled cooling of an interface surface or region between transducer probe 400 and a region of interest and beyond and beyond by suitably controlling the temperature of the coupling medium. The suitable temperature for such coupling medium can be achieved in various manners, and utilize various feedback systems, such as thermocouples, thermistors or any other device or system configured for temperature measurement of a coupling medium. Such controlled cooling can be configured to further facilitate spatial and/or thermal energy control of transducer probe 400.
In accordance with an exemplary embodiment, with additional reference to FIG. 11, acoustic coupling and cooling 1140 can be provided to acoustically couple energy and imaging signals from transducer probe 1104 to and from the region of interest 1102, to provide thermal control at the probe to region-of-interest interface 1110 and deeper into tissue, and to remove potential waste heat from the transducer probe at region 1144. Temperature monitoring can be provided at the coupling interface via a thermal sensor 1146 to provide a mechanism of temperature measurement 1148 and control via control system 1106 and a thermal control system 1142. Thermal control may consist of passive cooling such as via heat sinks or natural conduction and convection or via active cooling such as with peltier thermoelectric coolers, refrigerants, or fluid-based systems comprised of pump, fluid reservoir, bubble detection, flow sensor, flow channels/tubing 1144 and thermal control 1142.
Monitoring and sensing components 408 can comprise various motion and/or position sensors 416, temperature monitoring sensors 418, user control and feedback switches 414 and other like components for facilitating control by control system 300, e.g., to facilitate spatial and/or temporal control through open-loop and closed-loop feedback arrangements that monitor various spatial and temporal characteristics.
Motion mechanism 410 can comprise manual operation, mechanical arrangements, or some combination thereof. For example, a motion mechanism 422 can be suitably controlled by control system 300, such as through the use of accelerometers, encoders or other position/orientation devices 416 to determine and enable movement and positions of transducer probe 400. Linear, rotational or variable movement can be facilitated, e.g., those depending on the treatment application and tissue contour surface.
Transducer 404 can comprise one or more transducers configured for producing conformal lesions of thermal injury in superficial human tissue within a region of interest through precise spatial and temporal control of acoustic energy deposition. Transducer 404 can also comprise one or more transduction elements and/or lenses 412. The transduction elements can comprise a piezoelectrically active material, such as lead zirconante titanate (PZT), or any other piezoelectrically active material, such as a piezoelectric ceramic, crystal, plastic, and/or composite materials, as well as lithium niobate, lead titanate, barium titanate, and/or lead metaniobate. In addition to, or instead of, a piezoelectrically active material, transducer 404 can comprise any other materials configured for generating radiation and/or acoustical energy. Transducer 404 can also comprise one or more matching layers configured along with the transduction element such as coupled to the piezoelectrically active material. Acoustic matching layers and/or damping may be employed as necessary to achieve the desired electroacoustic response.
In accordance with an exemplary embodiment, the thickness of the transduction element of transducer 404 can be configured to be uniform. That is, a transduction element 412 can be configured to have a thickness that is substantially the same throughout. In accordance with another exemplary embodiment, the thickness of a transduction element 412 can also be configured to be variable. For example, transduction element(s) 412 of transducer 404 can be configured to have a first thickness selected to provide a center operating frequency of approximately 2 MHz to 50 MHz, such as for imaging applications. Transduction element 412 can also be configured with a second thickness selected to provide a center operating frequency of approximately 2 to 50 MHz, and typically between 5 MHz and 25 MHz for therapy application. Transducer 404 can be configured as a single broadband transducer excited with at least two or more frequencies to provide an adequate output for generating a desired response. Transducer 404 can also be configured as two or more individual transducers, wherein each transducer comprises one or more transduction element. The thickness of the transduction elements can be configured to provide center-operating frequencies in a desired treatment range.
Transducer 404 may be composed of one or more individual transducers in any combination of focused, planar, or unfocused single-element, multi-element, or array transducers, including 1-D, 2-D, and annular arrays; linear, curvilinear, sector, or spherical arrays; spherically, cylindrically, and/or electronically focused, defocused, and/or lensed sources. For example, with reference to an exemplary embodiment depicted in FIG. 5, transducer 500 can be configured as an acoustic array 502 to facilitate phase focusing. That is, transducer 500 can be configured as an array of electronic apertures that may be operated by a variety of phases via variable electronic time delays. By the term “operated,” the electronic apertures of transducer 500 may be manipulated, driven, used, and/or configured to produce and/or deliver an energy beam corresponding to the phase variation caused by the electronic time delay. For example, these phase variations can be used to deliver defocused beams 508, planar beams 504, and/or focused beams 506, each of which may be used in combination to achieve different physiological effects in a region of interest 510. Transducer 500 may additionally comprise any software and/or other hardware for generating, producing and or driving a phased aperture array with one or more electronic time delays.
Transducer 500 can also be configured to provide focused treatment to one or more regions of interest using various frequencies. In order to provide focused treatment, transducer 500 can be configured with one or more variable depth devices to facilitate treatment. For example, transducer 500 may be configured with variable depth devices disclosed in U.S. patent application Ser. No. 10/944,500, entitled “System and Method for Variable Depth Ultrasound”, filed on Sep. 16, 2004, having at least one common inventor and a common Assignee as the present application, and incorporated herein by reference. In addition, transducer 500 can also be configured to treat one or more additional ROI 510 through the enabling of sub-harmonics or pulse-echo imaging, as disclosed in U.S. patent application Ser. No. 10/944,499, entitled “Method and System for Ultrasound Treatment with a Multi-directional Transducer”, filed on Sep. 16, 2004, having at least one common inventor and a common Assignee as the present application, and also incorporated herein by reference.
Moreover, any variety of mechanical lenses or variable focus lenses, e.g. liquid-filled lenses, may also be used to focus and or defocus the sound field. For example, with reference to exemplary embodiments depicted in FIGS. 6A and 6B, transducer 600 may also be configured with an electronic focusing array 604 in combination with one or more transduction elements 606 to facilitate increased flexibility in treating ROI 610. Array 604 may be configured in a manner similar to transducer 502. That is, array 604 can be configured as an array of electronic apertures that may be operated by a variety of phases via variable electronic time delays, for example, T1, T2 . . . Tj. By the term “operated,” the electronic apertures of array 604 may be manipulated, driven, used, and/or configured to produce and/or deliver energy in a manner corresponding to the phase variation caused by the electronic time delay. For example, these phase variations can be used to deliver defocused beams, planar beams, and/or focused beams, each of which may be used in combination to achieve different physiological effects in ROI 610.
Transduction elements 606 may be configured to be concave, convex, and/or planar. For example, in an exemplary embodiment depicted in FIG. 6A, transduction elements 606[A] are configured to be concave in order to provide focused energy for treatment of ROI 610. Additional embodiments are disclosed in U.S. patent application Ser. No. 10/944,500, entitled “Variable Depth Transducer System and Method”, and again incorporated herein by reference.
In another exemplary embodiment, depicted in FIG. 6B, transduction elements 606[B] can be configured to be substantially flat in order to provide substantially uniform energy to ROI 610. While FIGS. 6A and 6B depict exemplary embodiments with transduction elements 604 configured as concave and substantially flat, respectively, transduction elements 604 can be configured to be concave, convex, and/or substantially flat. In addition, transduction elements 604 can be configured to be any combination of concave, convex, and/or substantially flat structures. For example, a first transduction element can be configured to be concave, while a second transduction element can be configured to be substantially flat.
With reference to FIGS. 8A and 8B, transducer 404 can be configured as single-element arrays, wherein a single-element 802, e.g., a transduction element of various structures and materials, can be configured with a plurality of masks 804, such masks comprising ceramic, metal or any other material or structure for masking or altering energy distribution from element 802, creating an array of energy distributions 808. Masks 804 can be coupled directly to element 802 or separated by a standoff 806, such as any suitably solid or liquid material.
An exemplary transducer 404 can also be configured as an annular array to provide planar, focused and/or defocused acoustical energy. For example, with reference to FIGS. 10A and 10B, in accordance with an exemplary embodiment, an annular array 1000 can comprise a plurality of rings 1012, 1014, 1016 to N. Rings 1012, 1014, 1016 to N can be mechanically and electrically isolated into a set of individual elements, and can create planar, focused, or defocused waves. For example, such waves can be centered on-axis, such as by methods of adjusting corresponding transmit and/or receive delays, T1, T2, T3 . . . TN. An electronic focus can be suitably moved along various depth positions, and can enable variable strength or beam tightness, while an electronic defocus can have varying amounts of defocusing. In accordance with an exemplary embodiment, a lens and/or convex or concave shaped annular array 1000 can also be provided to aid focusing or defocusing such that any time differential delays can be reduced. Movement of annular array 1000 in one, two or three-dimensions, or along any path, such as through use of probes and/or any conventional robotic arm mechanisms, may be implemented to scan and/or treat a volume or any corresponding space within a region of interest.
Transducer 404 can also be configured in other annular or non-array configurations for imaging/therapy functions. For example, with reference to FIGS. 10C-10F, a transducer can comprise an imaging element 1012 configured with therapy element(s) 1014. Elements 1012 and 1014 can comprise a single-transduction element, e.g., a combined imaging/transducer element, or separate elements, can be electrically isolated 1022 within the same transduction element or between separate imaging and therapy elements, and/or can comprise standoff 1024 or other matching layers, or any combination thereof. For example, with particular reference to FIG. 10F, a transducer can comprise an imaging element 1012 having a surface 1028 configured for focusing, defocusing or planar energy distribution, with therapy elements 1014 including a stepped-configuration lens configured for focusing, defocusing, or planar energy distribution.
In accordance with another aspect of the invention, transducer probe 400 may be configured to provide one, two or three-dimensional treatment applications for focusing acoustic energy to one or more regions of interest. For example, as discussed above, transducer probe 400 can be suitably diced to form a one-dimensional array, e.g., a transducer comprising a single array of sub-transduction elements.
In accordance with another exemplary embodiment, transducer 404 may be suitably diced in two-dimensions to form a two-dimensional array. For example, with reference to FIG. 9, an exemplary two-dimensional array 900 can be suitably diced into a plurality of two-dimensional portions 902. Two-dimensional portions 902 can be suitably configured to focus on the treatment region at a certain depth, and thus provide respective slices 9O4, 907 of the treatment region. As a result, the two-dimensional array 900 can provide a two-dimensional slicing of the image place of a treatment region, thus providing two-dimensional treatment.
In accordance with another exemplary embodiment, transducer probe 400 may be suitably configured to provide three-dimensional treatment. For example, to provide three dimensional treatment of a region of interest, with reference again to FIG. 3, a three-dimensional system can comprise transducer probe 400 configured with an adaptive algorithm, such as, for example, one utilizing three-dimensional graphic software, contained in a control system, such as control system 300. The adaptive algorithm is suitably configured to receive two-dimensional imaging, temperature and/or treatment information relating to the region of interest, process the received information, and then provide corresponding three-dimensional imaging, temperature and/or treatment information.
In accordance with an exemplary embodiment, with reference again to FIG. 9, an exemplary three-dimensional system can comprise a two-dimensional array 900 configured with an adaptive algorithm to suitably receive 904 slices from different image planes of the treatment region, process the received information, and then provide volumetric information 906, e.g., three-dimensional imaging, temperature and/or treatment information. Moreover, after processing the received information with the adaptive algorithm, the two-dimensional array 900 may suitably provide therapeutic heating to the volumetric region 906 as desired.
Alternatively, rather than utilizing an adaptive algorithm, such as three-dimensional software, to provide three-dimensional imaging and/or temperature information, an exemplary three-dimensional system can comprise a single transducer 404 configured within a probe arrangement to operate from various rotational and/or translational positions relative to a target region.
To further illustrate the various structures for transducer 404, with reference to FIG. 7, ultrasound therapy transducer 700 can be configured for a single focus, an array of foci, a locus of foci, a line focus, and/or diffraction patterns. Transducer 700 can also comprise single elements, multiple elements, annular arrays, one-, two-, or three-dimensional arrays, broadband transducers, and/or combinations thereof, with or without lenses, acoustic components, and mechanical and/or electronic focusing. Transducers configured as spherically focused single elements 702, annular arrays 704, annular arrays with damped regions 706, line focused single elements 708, 1-D linear arrays 710, 1-D curvilinear arrays in concave or convex form, with or without elevation focusing, 2-D arrays, and 3-D spatial arrangements of transducers may be used to perform therapy and/or imaging and acoustic monitoring functions. For any transducer configuration, focusing and/or defocusing may be in one plane or two planes via mechanical focus 720, convex lens 722, concave lens 724, compound or multiple lenses 726, planar form 728, or stepped form, such as illustrated in FIG. 10F. Any transducer or combination of transducers may be utilized for treatment. For example, an annular transducer may be used with an outer portion dedicated to therapy and the inner disk dedicated to broadband imaging wherein such imaging transducer and therapy transducer have different acoustic lenses and design, such as illustrated in FIG. 10C-10F.
Various shaped treatment lesions can be produced using the various acoustic lenses and designs in FIGS. 10A-10F. For example, cigar-shaped lesions may be produced from a spherically focused source, and/or planar lesions from a flat source. Concave planar sources and arrays can produce a “V-shaped” or ellipsoidal lesion. Electronic arrays, such as a linear array, can produce defocused, planar, or focused acoustic beams that may be employed to form a wide variety of additional lesion shapes at various depths. An array may be employed alone or in conjunction with one or more planar or focused transducers. Such transducers and arrays in combination produce a very wide range of acoustic fields and their associated benefits. A fixed focus and/or variable focus lens or lenses may be used to further increase treatment flexibility. A convex-shaped lens, with acoustic velocity less than that of superficial tissue, may be utilized, such as a liquid-filled lens, gel-filled or solid gel lens, rubber or composite lens, with adequate power handling capacity; or a concave-shaped, low profile, lens may be utilized and composed of any material or composite with velocity greater than that of tissue. While the structure of transducer source and configuration can facilitate a particular shaped lesion as suggested above, such structures are not limited to those particular shapes as the other spatial parameters, as well as the temporal parameters, can facilitate additional shapes within any transducer structure and source.
Through operation of ultrasound system 100, a method for treating stretch marks can be realized that can facilitate effective and efficient therapy without creating chronic injury to human tissue. For example, a user may first select one or more transducer probe configurations for treating a region of interest. The user may select any probe configuration described herein. Because the treatment region ranges from approximately 0 mm to 1 cm, exemplary transducer probes may include, for example, an annular array, a variable depth transducer, a mechanically moveable transducer, a cylindrical-shaped transducer, a linear array, a single element transducer and the like. As used herein, the term user may include a person, employee, doctor, nurse, and/or technician, utilizing any hardware and/or software of other control systems.
Once one or more transducers are selected, the user may then image a region of interest in order to plan a treatment protocol. By imaging a region of interest, the user may user the same treatment transducer probe and/or one or more additional transducers to image the region of interest at a high resolution. In one embodiment, the transducer may be configured to facilitate high speed imaging over a large region of interest to enable accurate imaging over a large region of interest. In another embodiment, ultrasound imaging may include the use of Doppler flow monitoring and/or color flow monitoring. In addition other means of imaging such as MRI, X-Ray, PET, infrared or others can be utilized separately or in combination for imaging and feedback of the superficial tissue and the vascular tissue in the region of interest.
In accordance with another exemplary embodiment, with reference to FIG. 12, an exemplary treatment system 200 can be configured with and/or combined with various auxiliary systems to provide additional functions. For example, an exemplary treatment system 1200 for treating a region of interest 1206 can comprise a control system 1202, a probe 1204, and a display 1208. Treatment system 1200 further comprises an auxiliary imaging modality 1274 and/or auxiliary monitoring modality 1272 may be based upon at least one of photography and other visual optical methods, magnetic resonance imaging (MRI), computed tomography (CT), optical coherence tomography (OCT), electromagnetic, microwave, or radio frequency (RF) methods, positron emission tomography (PET), infrared, ultrasound, acoustic, or any other suitable method of visualization, localization, or monitoring of stretch marks within region-of-interest 1206, including imaging/monitoring enhancements. Such imaging/monitoring enhancement for ultrasound imaging via probe 1204 and control system 1202 could comprise M-mode, persistence, filtering, color, Doppler, and harmonic imaging among others; furthermore an ultrasound treatment system 1270, as a primary source of treatment, may be combined with a secondary source of treatment 1276, including radio frequency (RF), intense pulsed light (IPL), laser, infrared laser, microwave, or any other suitable energy source.
By planning a treatment protocol, the user may choose one or more spatial and/or temporal characteristics to provide conformal ultrasound energy to a region of interest. For example, the user may select one or more spatial characteristics to control, including, for example, the use one or more transducers, one or more mechanical and/or electronic focusing mechanisms, one or more transduction elements, one or more placement locations of the transducer relative to the region of interest, one or more feedback systems, one or more mechanical arms, one or more orientations of the transducer, one or more temperatures of treatment, one or more coupling mechanisms and/or the like.
In one exemplary embodiment, ablation of stretch marks and surrounding tissues to temperatures greater than about 60 C, is utilized. In order to facilitate producing arrays of small thermal injury zones, an ultrasound transducer can be configured to propagate energy as a wave with relatively little scattering, over depths up to many centimeters in tissue depending on the ultrasound frequency. Depending on the size of the stretch mark to be treated, the treatment zone size can be achieved by varying the ultrasound wavelength. Because attenuation (absorption, mainly) of ultrasound by tissue increases with frequency, use of lower frequency ultrasound can maximize treatment efficiency.
In addition, the user may choose one or more temporal characteristics to control in order to facilitate treatment of the region of interest. For example, the user may select and/or vary the treatment time, frequency, power, energy, amplitude and/or the like in order to facilitate temporal control. For more information on selecting and controlling ultrasound spatial and temporal characteristics, see U.S. application Ser. No. 11/163,148, entitled “Method and System for Controlled Thermal Injury,” filed Oct. 6, 2005 and previously incorporated herein by reference.
After planning of a treatment protocol is complete, the treatment protocol can be implemented. That is, a transducer system can be used to deliver ultrasound energy to a treatment region to ablate select tissue in order to treat stretch marks. By delivering energy, the transducer may be driven at a select frequency, a phased array may be driven with certain temporal and/or spatial distributions, a transducer may be configured with one or more transduction elements to provide focused, defocused and/or planar energy, and/or the transducer may be configured and/or driven in any other ways hereinafter devised.
For example and in accordance with another aspect of the present invention, and with reference to an exemplary embodiment depicted in FIG. 13A, one or more treated zones 1340 are configured to produce regions of ablation within a treatment volume in spatially defined patterns. These spatially defined patterns include, for example, a discrete locus of treatment spots and/or a one- two- and/or three-dimensional matrix of damage. These spatially defined patterns may be desired rather than heating and destroying an entire volume of the tissue. In such a treatment the surrounding undamaged tissue aids rapid healing and recovery.
Transducer probe 204 and/or any other transducers (not shown) can be mechanically and/or electronically scanned 1326 to extend the treatment zone over a large area, and transducer probe 204 can be further scanned or moved 1328 to further enlarge the treatment zone. The zones of treatment may be placed at depths ranging from approximately 0 to 10 mm, or the maximum depth of the stretch marks or deep dermis. Treatment zones can run parallel and/or perpendicular to stretch marks and/or surrounding tissue to create anisotropic patterns of tissue damage, and/or can cover a two-dimensional matrix extending over the disfiguring pattern of stretch marks.
In accordance with another aspect of the present invention, and with reference to an exemplary embodiment illustrated in FIG. 13B, a treated zone 1360 may extend throughout regions of the dermis, and may even extend to the epidermis 1362. In addition as treated zone 1360 increases in depth, its cross section may increase from a small size 1364 (about a sub millimeter) in a shallow region near or at the epidermis, to a medium size 1366 (about a sub millimeter to a millimeter) in a middle zone near and/or at the mid dermis, to large size 1368 (about a millimeter) in deep zones near and/or at the deep dermis. Furthermore a single treated zone can have a shape expanding in cross section with depth, and/or be composed of the fusion of several smaller treatment zones. Spacing of treatment zones can be on the order of the treatment zone size or zones or macro-zones may be fused together horizontally. The ultrasound beam can be spatially and/or temporally controlled by changing the position of the transducer, its frequency, treatment depth, drive amplitude, and timing via the control system. (See, for example, U.S. application Ser. No. 10/163,148, filed on Oct. 6, 2005, and entitled METHOD AND SYSTEM FOR CONTROLLED THERMAL INJURY, hereby incorporated by reference).
Upon treatment, the steps outlined above can be repeated one or more additional times to provide for optimal treatment results. Different ablation sizes and shapes may affect the recovery time and time between treatments. For example, in general, the larger the surface area of the treatment lesion, the faster the recovery. The series of treatments can also enable the user to tailor additional treatments in response to a patient's responses to the ultrasound treatment.
The present invention may be described herein in terms of various functional components and processing steps. It should be appreciated that such components and steps may be realized by any number of hardware components configured to perform the specified functions. For example, the present invention may employ various medical treatment devices, visual imaging and display devices, input terminals and the like, which may carry out a variety of functions under the control of one or more control systems or other control devices. In addition, the present invention may be practiced in any number of medical contexts and that the exemplary embodiments relating to a system as described herein are merely indicative of exemplary applications for the invention. For example, the principles, features and methods discussed may be applied to any medical application. Further, various aspects of the present invention may be suitably applied to other applications, such as other medical or industrial applications.

## Claims

1. A method for treating stretch marks, said method comprising:
imaging a treatment region comprising at least one stretch mark;
selecting a probe configuration based on at least one of a spatial parameter and a temporal parameter based on the imaging of the at least one stretch mark;
verifying said at least one of a spatial parameter and a temporal parameter of said probe;
confirming acoustic coupling of said probe to said treatment region comprising at least one stretch mark; and
applying ultrasound energy using the selected probe configuration to ablate a portion of said treatment region comprising at least one stretch mark to facilitate treatment of said at least one stretch mark.

2. The method of claim 1, wherein said step of applying ultrasound energy includes applying conformal ultrasound energy in the range of about 2 MHz to about 50 MHz.

3. The method of claim 1, wherein said step of applying ultrasound energy includes applying conformal ultrasound energy in the range of about 2 MHz to about 25 MHz.

4. The method of claim 1, further comprising a step of re-imaging said treatment region to confirm ablation of said portion of said treatment region.

5. The method of claim 1, further comprising monitoring results of said applying ultrasound energy to ablate a portion of said treatment region comprising at least one stretch mark.

6. A method for providing treatment of stretch marks, said method comprising:
localizing a targeted region comprising at least one of an epidermis, a dermis, a deep dermis, and a fibrous fascia within a region of interest;
identifying at least one stretch mark in said targeted region;
targeting delivery of ablative ultrasound energy from a transducer probe to said at least one stretch mark in said targeted region; and
monitoring results of said targeted delivery within said at least one stretch mark in said targeted region during and after said targeted delivery to continue planning of treatment.

7. A method of providing a treatment for at least one stretch mark by a reduction in appearance of the at least one stretch mark in a skin surface, the method comprising:
imaging a treatment area below a skin surface, said treatment area comprising at least a portion of at least one stretch mark;
identifying said at least a portion of said at least one stretch mark in said treatment area;
delivering ultrasound energy to said at least a portion of said at least one stretch mark;
coagulating tissue in said at least a portion of said at least one stretch mark;
monitoring said at least one stretch mark for a reduction in appearance of said at least one stretch mark in said skin surface.

8. The method of claim 7, wherein said delivering ultrasound energy to said at least a portion of said at least one stretch mark further comprises adjustably controlling of at least one spatial parameter and at least one temporal parameter of an ultrasound energy source to generate a conformal lesion of a specifically targeted shape, size and orientation.

9. The method according to claim 7 further comprising generating three-dimensional imaging information of said at least one stretch mark.

10. The method according to claim 7, further comprising forming a lesion in said at least a portion of said at least one stretch mark.