for the following defined terms , these definitions shall be applied , unless a different definition is given in the claims or elsewhere in this specification . all numeric values are herein assumed to be modified by the term “ about ”, whether or not explicitly indicated . the term “ about ” generally refers to a range of numbers that one of skill in the art would consider equivalent to the recited value ( i . e ., having the same function or result ). in many instances , the term “ about ” may be indicative as including numbers that are rounded to the nearest significant figure . the recitation of numerical ranges by endpoints includes all numbers within that range ( e . g ., 1 to 5 includes 1 , 1 . 5 , 2 , 2 . 75 , 3 , 3 . 80 , 4 , and 5 ). although some suitable dimensions ranges and / or values pertaining to various components , features and / or specifications are disclosed , one of skill in the art , incited by the present disclosure , would understand desired dimensions , ranges and / or values may deviate from those expressly disclosed . as used in this specification and the appended claims , the singular forms “ a ”, “ an ”, and “ the ” include plural referents unless the content clearly dictates otherwise . as used in this specification and the appended claims , the term “ or ” is generally employed in its sense including “ and / or ” unless the content clearly dictates otherwise . the terms “ preferential ” and “ preferentially ” mean that the modified element is disproportionally affected relative to other elements . for example , the phrase “ preferentially exciting a signal in nerve tissue ” means the excitation of the signal in nerve tissue is greater than in other tissue . this is in contrast to merely exciting a signal in nerve tissue , which may be understood to mean that other tissues may be equally excited , or non - preferentially exciting a signal in nerve tissue , which may be understood to mean that other tissues are equally excited the following detailed description should be read with reference to the drawings in which similar elements in different drawings are numbered the same . the detailed description and the drawings , which are not necessarily to scale , depict illustrative embodiments and are not intended to limit the scope of the invention . the illustrative embodiments depicted are intended only as exemplary . selected features of any illustrative embodiment may be incorporated into an additional embodiment unless clearly stated to the contrary . fig1 is a diagram of an example imaging and nerve modulation catheter 100 that can be employed to identify nerve tissue and deliver a localized therapy to the nerve tissue . as shown in one implementation , the catheter 100 includes a distal inflatable balloon portion 102 that can be routed to a treatment site inside a patient to image and deliver therapy to that treatment site ; a proximal end 104 that remains outside a patient during treatment and facilitates connection of various equipment to the catheter 100 ; and an elongate member or catheter shaft 106 that couples the proximal - end equipment to the distal inflatable balloon portion . the catheter &# 39 ; s elongate member 106 may include one or more internal lumens ( not shown in fig1 ). the lumens allow inflation fluid to be delivered distally from an external inflation fluid source 108 to an internal chamber of the balloon 102 . the elongate member 106 also includes conductors ( not shown ) that carry electrical signals from components such as sensing elements ( e . g ., sensing elements 112 a / 112 b , which can be seen in fig2 ) and ablation elements ( e . g ., ablation element 114 , which can be seen in fig2 ) in the balloon 102 to a signal processor 110 at the proximal end of the catheter 100 . the signal processor 110 can process the electrical signals to electrically characterize signals from the sensing elements 112 a / 112 b . in particular , the signal processor 110 , in some implementations , generates visual displays , such as isochronal or isopotential maps of the tissue , which a physician may use to identify aberrant electrical pathways at locations in the body tissue that may be candidates for nerve modulation or maps which a physician may use to identify nerve tissue . the visual displays may be provided in a user interface 116 ( e . g ., a flat panel display , or other suitable output device ). the signal processor 110 can include circuitry for receiving acoustic or light signals or biopotential signals ( e . g ., differential amplifiers or other amplifiers that sense biopotential signals and amplify them to levels that can be used in further processing ) and processing the signals in a manner that permits their subsequent analysis , for example by a medical professional delivering or considering delivering therapy to a patient . in some implementations , the signal processor 110 includes dedicated circuitry ( e . g ., discrete logic elements and one or more microcontrollers ; application - specific integrated circuits ( asics ); or specially configured programmable devices , such as , for example , programmable logic devices ( plds ) or field programmable gate arrays ( fpgas )) for processing biopotential signals and displaying a graphical representation of the signals in a user interface . in some implementations , the signal processor 110 includes a general purpose microprocessor and / or a specialized microprocessor ( e . g ., a digital signal processor , or dsp , which may be optimized for processing graphical or a biometric information ) that executes instructions to receive , analyze and display information associated with the received signals . in such implementations , the signal processor 110 can include program instructions , which when executed , perform part of the signal processing . program instructions can include , for example , firmware , microcode or application code that is executed by microprocessors or microcontrollers . the above - mentioned implementations are merely exemplary , and the reader will appreciate that the signal processor 110 can take any suitable form . a controller 118 at the proximal end can control the sensing elements 112 a / 112 b and / or the nerve modulation elements 114 to generate probing signals and / or therapeutic emissions . in some embodiments , a separate controller may be used for controlling the nerve modulation elements 114 . the controller 118 itself can take many different forms . in some implementations , the controller 118 is a dedicated electrical circuit employing various sensors , logic elements and actuators . in other implementations , the controller 118 is a computer - based system that includes a programmable element , such as a microcontroller or microprocessor , which can execute program instructions stored in a corresponding memory or memories . such a computer - based system can take many forms , include many input and output devices ( e . g ., a user interface and other common input and output devices associated with a computing system , such as keyboards , point devices , touch screens , discrete switches and controls , printers , network connections , indicator lights , etc .) and may be integrated with other system functions , such as monitoring equipment , a computer network , other devices that are typically employed during a procedure , etc . for example , a single computer - based system may include a processor that executes instructions to provide the controller function , display imaging information associated with a procedure ( e . g ., from an imaging device ); display pressure , temperature and time information ( e . g ., elapsed time since a given phase of treatment was started ); and serve as an overall interface to the catheter 100 . in general , various types of controllers are possible and contemplated , and any suitable controller 118 can be employed . moreover , in some implementations , the controller 118 and the signal processor 110 may be part of a single computer - based system , and both control and signal processing functions may be provided , at least in part , by the execution of program instructions in a single computer - based system . the catheter 100 shown in fig1 is an over - the - wire type catheter . such a catheter 100 uses a guidewire 120 , extending from the distal end of the catheter 100 . in some implementations , the guidewire 120 may be pre - positioned inside a patient &# 39 ; s body ; once the guidewire 120 is properly positioned , the balloon 102 ( in a deflated state ) and the elongate member 106 can be routed over the guidewire 120 to a treatment site . in some implementations , the guidewire 120 and balloon portion 102 of the catheter 100 may be advanced together to a treatment site inside a patient &# 39 ; s body , with the guidewire 120 leading the balloon 102 by some distance ( e . g ., several inches ). when the guidewire portion 120 reaches the treatment site , the balloon 102 may then be advanced over the guidewire 120 until it also reaches the treatment site . other implementations are contemplated , such as steerable catheters that do not employ a guidewire . moreover , some implementations include an introducer sheath that can function similar to a guidewire , and in particular , that can be initially advanced to a target site , after which other catheter portions can be advanced through the introducer sheath . the catheter 100 can include a manipulator ( not shown ), by which a medical practitioner may navigate the guidewire 120 and / or balloon 102 through a patient &# 39 ; s body to a treatment site . in some implementations , release of cryogenic fluid into a cooling chamber may inflate the balloon 102 to a shape similar to that shown in fig1 . in other implementations , a pressure source 108 may be used to inflate the balloon 102 independently of the release of cryogenic fluid into the internal chamber of the balloon 102 . the pressure source 108 may also be used to inflate an anchor member on the end of the guidewire 120 ( not shown ). the catheter 100 includes a connector for connecting to the user interface 116 , the controller 118 and the signal processor 110 . the user interface may include monitoring equipment that may be used , for example , to monitor temperature or pressure at the distal end of the catheter 100 . as indicated above , the monitoring equipment may be integrated in a single system that also provides the controller and signal processor . to aid in positioning the balloon 102 of the catheter 100 inside a patient &# 39 ; s body , various marker bands ( not shown ) can also be disposed at the distal and proximal ends of the catheter 100 . the marker bands may be radio - opaque when the catheter is viewed by x - ray or other imaging techniques . other variations in the catheter 100 are contemplated . a guidewire may be arranged differently than shown , and may be separately controlled from the balloon portion of the catheter . moreover , in some implementations , a guidewire may not be used . fig2 illustrates some of the internal details of balloon 102 . the balloon 102 includes a balloon wall 122 that may be formed from a polymer including , but not limited to , polyolefin copolymer , polyester , polyethylene terephthalate , polyethylene , polyether - block - amide , polyamide , polyimide , nylon , latex , or urethane . balloon wall 122 is preferably transparent and is also preferably compliant . balloon 102 includes an inner module 124 that may carry the sensing element 112 a / 112 b and the nerve modulation elements 114 . the inner module 124 may be cylindrical and may be rotatably mounted with respect to the balloon . an electrical actuation element 126 may allow rotation of the inner module 124 with respect to the balloon . the sensing elements 112 a / 112 b may be configured to identify nerve tissue and may comprise photo - acoustic elements , ultrasound elements , light sensors or other suitable nerve detection elements . photo - acoustic imaging uses the physical phenomenon of an acoustic wave being produced from a sample that is stimulated using electromagnetic energy . generally , the tissue is irradiated using high - intensity pulses of light or radiofrequency energy . these pulses are preferably short ( 1 - 100 ns ). the wavelength of the pulsed of light may vary and , in some embodiments , may be in the range of about 400 - 500 nm ( e . g ., 450 nm ) or , in some other embodiments , may be about 1200 nm or greater . these are just examples . broadband acoustic waves are then generated from absorption of the energy in the tissue within the irradiated volume . short ( e . g . nanosecond ) pulses may generate the highest resolution acoustic return signals . the acoustic return signals can be detected using an ultrasound detector and subsequently processed to provide spatial organization to generate an image of the target tissue . the strength of the acoustic return signal is related to the intensity and the wave - length of the pulses of coherent light and also related to the local optical absorption coefficient of the target tissue . using photo - acoustic imaging , it is possible to distinguish between different tissue types at a high level of resolution ( e . g . on the order of about 20 - 200 micrometers ). using preferential contrast dyes that have high optical absorption coefficients , photo - acoustic imaging techniques may be performed on the cellular and molecular level . sensing elements 112 a may be configured to emit pulses of coherent light ( e . g ., having a wavelength in the range of about 400 - 500 or having a wavelength of about 1200 nm or greater ) and sensing elements 112 b may be configured to receive acoustic signals generated by the pulses of coherent light in the nerve tissue . for example , sensor elements 112 a may be laser diodes and sensor elements 112 b may be transducers . sensor elements 112 a preferably are configured to focus the coherent light at a focus point . the focus point may be a predetermined focus point or may be movable . the focus point may , for example be moved through the use of element actuators ( not shown ) under each of the sensor elements 112 a , through using sensor elements 112 a as a phased array , through the use of one or more lenses or other suitable means . the sensor elements 112 b ( the receiving elements ) may be configured as a phased array , which allows either the elements or the controller 118 or signal processor 110 to determine where the reflected signals are coming from . in this manner , a three dimensional map that includes depth through the vessel wall can be created to identify the presence of nerve tissue . in some embodiments , the sensor elements 112 b can also measure temperature and detect temperature changes . ultrasonic signals generated in the tissue are a function of the material properties of the tissue . pertinent properties are the speed of sound through the material , which changes with temperature , and the thermal expansion of the material with temperature . these properties change as temperature changes and affect , in a predictable manner , the ultrasonic waves generated by the tissue . the signal processor 110 can therefore be configured to measure temperature deep in the tissue and / or detect temperature changes in the tissue . such measurements may be useful in temperature dependent nerve modulation techniques to determine the temperatures at locations and the amount of time the tissue at those locations is exposed to particular temperatures . a dye that preferentially attaches to nerve tissue or to molecules found in higher concentrations in nerve tissue may be used in conjunction with the sensing elements 112 . the dye may have a high - optical absorption coefficient at a predetermined frequency and the sensing elements 112 a may emit coherent light at that frequency . in this manner , the sensitivity of the system to the dye and the corresponding nerve tissue may be heightened resulting in more effective or deeper imaging of the nerve tissue . such a dye may be injected by a separate needle into the area of interest prior to introduction of the catheter into the patient &# 39 ; s body , may be introduced through a lumen of the catheter into the body vessel or may be introduced through another suitable manner such as topically or orally . other focusing elements such as those described in commonly owned u . s . patent application ser . no . 61 / 324 , 164 and / or u . s . patent application publication no . us 2011 / 0257523 , the entire disclosures of which are herein incorporated by reference , may be used with either sensing elements 112 a , 112 b or , as described below , with ablation elements 114 . the inner module 124 also includes ablation elements 114 . preferably , ablation elements that can ablate at depth without disrupting intervening tissue are used . such ablation elements may include laser ablation elements and ultrasonic ablation elements . in some embodiments , sensing elements 112 a or 112 b can also function as the ablation elements . however , other ablation elements , such as radiofrequency ablation elements or cryogenic ablation elements may also be used . in the embodiment shown in fig2 , ablation elements 114 are ultrasonic ablation elements and are in the form of a phased array , which allows the ablation element to target the tissue at a selected depth of focus and may also allow the focal point to be moved laterally . in use , the catheter may be deployed percutaneously or intravascularly to a region of interest , and the balloon 102 may be expanded to fix the distal end of the catheter in place during the procedure . the balloon may preferably be expanded using a clear inflation fluid such as saline . sensing elements 112 a / 112 b may then be activated to create an image of the region of interest preferentially identifying the nerve tissue . in renal arteries , for example , nerve tissue generally lies at depths of between 2 and 8 mm . the inner module 124 may be rotated during imaging to create an image of the body vessel on all sides of the balloon to identify nerve tissue in the region proximate the balloon . once the nerve tissue is identified , the inner module may be rotated to aim the ablation elements 114 at the nerve tissue . the nerve tissue may then be ablated by activating the ablation elements 114 . the ablation elements 114 may be focused to ablate only the targeted nerve tissue . fig3 a illustrates the distal portion of an example catheter 200 in a body vessel lumen . catheter 200 includes a balloon 102 and a module 124 . the module 124 may be rotatable using actuation element 126 . module 124 includes ultrasonic phased arrays 130 and light emitting element 132 . light emitting element 132 emits short pulses of light 134 , which are selected to preferentially excite nerve tissue 136 . any nerve tissue 136 thereby emits acoustic waves 138 , which can be picked up by ultrasonic arrays 130 . the module may be rotated during this process to identify nerve tissue in the area of interest . as illustrated in fig3 b , once nerve tissue has been identified , the ultrasonic arrays can then focus ablation energy 140 to a focal point 142 to ablate the nerve tissue 136 . the module 124 can be rotated to ablate additional nerve tissue . the depth of field of the focal point may be modified altered , depending on the depth and location of the nerve tissue . those skilled in the art will recognize that the present invention may be manifested in a variety of forms other than the specific embodiments described and contemplated herein . accordingly , departure in form and detail may be made without departing from the scope and spirit of the present invention as described in the appended claims .
apparatuses for identifying nerve tissue and methods for making and using the same are disclosed . an example apparatus may include an elongate shaft having a distal region configured to be percutaneously deployed within a patient . an active imaging structure may be disposed on the distal region . the active imaging structure may be configured to remotely image nerve tissue by exciting a signal in nerve tissue from a percutaneous location and receiving the signal from a percutaneous location . the active imaging structure may include one or more probes .