the invention is a delivery catheter having imaging elements that facilitate visualization of the vasculature and catheter placement . the visualization provided by the delivery catheter of the invention helps to direct the flow of a fluid delivered or guide an interventional catheter to a treatment site . the design of the delivery catheter is especially - suited to be used with guide catheters , such as the type used to deliver contrast agents or place interventional catheters during endovascular procedures . the imaging element is located at or near the distal end of the delivery catheter . the imaging element is a part of an imaging assembly , such an ivus or photoacoustic imaging assembly . in certain embodiments , the imaging element is an ultrasound transducer , a piezoelectric micromachined ultrasound transducer , a capacitive micromachined ultrasound transducer , and a photoacoustic ultrasound transducer . catheters having the described imaging elements can be any type of catheter . catheters include any elongated intraluminal device that comprises a tube or shaft that is configured to enter a body lumen . many catheters for endovascular procedures are around 200 cm in total length and are administered via a cannula ( introducer ) that has been placed in an artery ( e . g ., the femoral , brachial , or radial artery ). catheters can be shorter , however , e . g ., between 100 and 200 cm , or longer , e . g ., between 200 and 400 cm . often a vascular catheter is delivered along a guidewire . the catheter may have a lumen running the length of the catheter to accept a guidewire ( over the rail ) or only a portion of catheter , typically the distal tip 410 , will have a guidewire lumen ( rapid exchange ). an inner lumen diameter of catheters of the invention ( including over the wire and rapid exchange configurations ) may be configured to receive one or more interventional catheters . in some instances , the catheters are placed with a guidewire . access guidewires ( generally “ guidewires ” herein ) are known medical devices used in the vasculature or other anatomical passageway to act as a guide for other devices , e . g ., a catheter . typically , the guidewire is inserted into an artery or vein and guided through the vasculature under fluoroscopy ( real time x - ray imaging ) to the location of interest . in some procedures one or more devices are delivered over the guide wire to diagnose , image , or treat the condition . guidewires typically have diameters of 0 . 010 ″ to 0 . 035 ″, with 0 . 014 ″ being the most common . guidewires ( and other intravascular objects ) are also sized in units of french , each french being ⅓ of a mm or 0 . 013 ″. guidewire lengths vary up to 400 cm , depending on the anatomy and work flow . the ends of the guidewire are denoted as distal ( far from the user , i . e ., inside the body ) and proximal ( near the user , i . e ., outside the body ). often a guidewire has a flexible distal tip portion about 3 cm long and a slightly less flexible portion about 30 to 50 cm long leading up to the tip with the remainder of the guidewire being stiffer to assist in maneuvering the guidewire through tortuous vasculature , etc . the tip of a guidewire typically has a stop or a hook to prevent a guided device , e . g ., a catheter from passing beyond the distal tip . in some embodiments , the tip can be deformed by a user to produce a desired shape . in some instances , the catheter comprises a resilient inner coil , making it possible to shape the catheter and deliver it to targeted anatomy , e . g ., the heart . such catheters are generally known as guide catheters and are often used to deliver fluids , e . g ., contrast agents to critical areas , or to deliver the catheter to tortuous locations , such as vasculature or the heart . because the catheters are rather narrow , e . g ., typically 8 french or less , it is also possible to guide a second catheter , for example , an imaging or therapeutic along the guide catheter to a desired location along the guide catheter . an embodiment of a catheter system 10 for use with the invention is shown in fig1 . fig1 is merely exemplary , as many other configurations of the catheter system 10 are possible to achieve the principles of the invention . the catheter system 10 includes a guide catheter 12 having a catheter body 14 with a proximal end 16 and a distal end 18 . a luminal opening at the distal end 18 allows a fluid to be delivered to a patient or an interventional catheter to be placed at a target location . catheter body 14 is flexible and defines a catheter axis 15 , and may include multiple lumens , such as a guidewire lumen , an inflation lumen , and a fluid delivery lumen . catheter 12 includes an imaging element 19 , proximal to the distal end 18 , and a housing 29 adjacent proximal hub 16 . typically , the imaging element 19 is placed on the external surface of the catheter body 14 . although , the imaging element 19 may also be placed , for example , within catheter body 14 . in certain embodiments , the imaging element 19 is placed in a ring array around the catheter body 14 . in this manner , the imaging element surrounds one or more lumens of the catheter body . preferably , the imaging element 19 is located right next to the distal end of 18 . ideally , the distal end 18 is less than 1 cm from the imaging element , preferably now more than a few millimeters . minimal distance d between the imaging element 19 and the distal end 18 allows the imaging element to image luminal surfaces and other objects that are substantially flush with the distal end 18 . additional lumens may be provided for other treatments , such as irrigation , aspiration , perfusion , or delivery of a device , e . g ., a stent . according to certain embodiments , the imaging element 19 is coupled to one or more signal lines 17 . the signal lines 17 couple to the imaging element 19 and run along an inner lumen of the catheter body . in certain embodiments , the signal lines 17 are bonded of laminated into a wall of the inner lumen . the signal lines 117 run along the inner wall towards proximal hub 16 . at proximal hub 16 , the single lines 17 are incorporated into an external cable . as shown the signal lines 17 ( as enclosed in an external cable ) extend through an external housing 29 coupled to the proximal hub 16 and attached to a patient interface module ( pim ) connector 31 . the pim connector may couple to an imaging system ( such as the imaging system 400 shown in fig5 ). the imaging system 400 is configured to control treatment , send and receive imaging data , and process imaging data . the imaging system is described in more detail hereinafter . in an embodiment , housing 29 includes a first connector 26 in communication with the guidewire lumen and optionally a second connector 28 in communication with e . g . a delivery lumen . the catheter 10 may be ridden over a guidewire running through the guidewire lumen to a position of interest . the guidewire lumen may be configured to receive a guidewire and an interventional catheter , which may also be riding over the guidewire . the interventional catheter may be for ablation , stent placement , angioplasty , imaging , pressure sensing , ect . both first and second connectors 26 , 28 may optionally comprise standard connectors , such as luer - loc ™ connectors . in certain embodiments , the guide catheter 10 further includes a balloon 22 or other expandable member . in addition to the imaging element , the expandable members 22 can be used effectively and reliably place the distal tip 18 of the catheter inside an ostium 310 of an artery 330 ( as shown in fig3 ). this placement assures that the length d of the guide catheter inside the ostium is appropriate for the procedure . in some embodiments , the guide catheter will have markers distal to the balloon 22 , allowing a surgeon to modify the length of the distance d as needed for the procedure . an additional benefit of the balloons is that fluids flushed from the catheter will be directed distally away from the tip . housing 29 additionally provides a connection to a pump 38 coupled to a fluid source , e . g ., saline or contrast . the pump 38 may be any pump suitable to deliver sufficient pressure to push the fluid . through the delivery lumen to be administered via the distal opening . in some embodiments , the pump 38 will be designed to give an initial burst of pressure to inflate a balloon 22 . the pump 38 may be a peristaltic pump , or the pump 38 may be a syringe . the reservoir 40 is any suitable reservoir to hold the fluid prior to delivery to the patient . the reservoir 40 may comprise pressure and temperature controls to maintain the fluid in optimum condition . in simple embodiments , both the pump 38 and the reservoir 40 take the form of a single syringe . in advanced embodiments , as shown in fig1 , the pump 38 and the particle reservoir 40 may be controlled by a controller 42 that is interfaced with patient monitoring equipment , e . g ., a blood oxygen sensor , or a pressure sensor . the controller 42 may include a processor , or is coupled to a processor , used to control flow of fluid into the catheter . in certain embodiments , the controller 42 is a computer . the controller may be included in imaging system 400 . for example , the controller 42 may be computer 449 . in such aspect , one computer may be used to control image collection and related processes and control fluid flow through the catheter 12 . as shown in fig1 , the catheter 1 is an over - the - wire guide catheter . over - the - wire guide catheters have a functional lumen that extends the entire length of the shaft , from the distal end to a proximal hub . devices , such as interventional catheters , introduced into the guide catheter are placed into the proximal end of the guide catheter , which is extending out of the patients body . the devices are pushed guided through the length of the guidewire . in addition to the over - the - wire guidewire configuration , catheters of the invention may alternatively have a rapid exchange configuration . rapid exchange catheters are characterized by the distal catheter shaft being from about 10 cm to about 40 cm long . the catheter does not require that another device , such an interventional catheter , be pushed through the entire length of the catheter . rather , an interventional catheter may ride along a guidewire , and enter the guide catheter through a catheter entry port located at a proximal end of the distal shaft . the rapid exchange guidewire allows one to more easily exchange varying interventional catheters into the delivery catheter . in addition , rapid exchange delivery catheters are compatible with virtually any length interventional catheter . fig2 depicts a catheter of the invention having a rapid exchange configuration . the catheter 300 has a distal shaft 50 defining a lumen 54 . the distal shaft is about 10 cm to about 40 cm in length . however , it is contemplated that the distal shaft 50 may be shorter or longer depending on the application . the distal shaft 50 includes an imaging element 119 located at or near the distal end 18 . like the catheter of fig1 , the distance between the imaging element 19 and the distal end 18 is preferably minimized such that the imaging plane is substantially flush with the absolute end of the catheter 300 . the distal shaft 50 includes proximal end 52 . the proximal end 52 terminates in a soft , atraumatic catheter port 53 leading to lumen 53 . typically , the imaging element 19 is placed on the external surface of the distal shaft 50 . although , the imaging element 19 may also be placed , for example , within distal shaft 50 . in certain embodiments , the imaging element 19 is placed in a ring array around the distal shaft 50 . the rapid exchange configuration may also include a balloon or expandable element . a push rod 21 is coupled to the proximal end 52 . the push rod 21 may be made of any suitable material . typically , the push rod 21 is made of stainless steel , such as 304 ss . the push rod 21 may be attached to the proximal end 52 via adhesive or thermal bonding . the push rod terminates at a proximal hub 83 . the proximal hub 83 may be used to control movement of the catheter 80 . alternatively , a handle separate from the proximal hub 83 may be used to manipulate and control movement of the guide catheter . according to certain embodiments , the imaging element 19 is coupled to one or more signal lines 17 . the signal lines 17 couple to the imaging element 19 and run along an inner lumen of the distal shaft 50 . in certain embodiments , the signal lines 17 are bonded of laminated into a wall of the distal shaft 50 . at the distal shaft , the signal lines 17 may transition to a sleeve 93 . the sleeve 93 may run next to a parallel to the push rod 21 . preferably , the sleeve 93 is coupled to the push rod 21 . the signal lines 17 run within sleeve 93 towards proximal hub 83 . at proximal hub 83 , the single lines 17 are incorporated into an external cable . as shown , the signal lines 17 ( as enclosed in an external cable ) are attached to a patient interface module ( pim ) connector 31 . the pim connector 31 may couple to an imaging system ( such as the imaging system 400 shown in fig5 ). the imaging system 400 is configured to control treatment , send and receive imaging data , and process imaging data . the imaging system is described in more detail hereinafter . as shown in fig3 , the guide catheter having imaging element 19 can be used to effectively and reliably place the distal tip 18 of the catheter inside an ostium 310 of an artery 330 . this visualization assures the guide catheter is appropriately placed inside the ostium for the procedure . fig4 a - 4c further depicts a guide catheter of the invention in use . in this embodiment , the catheter 200 has been placed in a lumen 280 , which may be an artery or vein on the order of the same size as the catheter 200 . the catheter 200 includes an imaging element 210 , a catheter body 230 , a distal tip 235 , a fluid delivery lumen 250 , and optionally a balloon 212 . the imaging element is able to send and receive imaging data so that an operator can visualize the vessel during the procedure . this allows the delivery catheter to be appropriately placed and remain in the appropriate place during the procedure . fluid contrast for external imaging is delivered , and then an interventional catheter is introduced through the delivery catheter . the interventional catheter may be used to ablate or morcellate tissue at a treatment site in the artery , for example . the sequence of insertion , fluid delivery , and interventional catheter introduction is shown in fig4 a - 4c , respectively . as shown in fig4 a , prior to fluid delivery , the imaging element 210 , positioned near the distal tip 235 , is placed within a biological lumen 280 . the imaging element 210 allows one to maintain , through visualization , the proper positioning of the catheter 200 during a procedure . once the catheter 200 is in place with the guidance of the imaging element 210 , a balloon 212 can be inflated in order to assist in maintaining the positioning of the guide catheter 200 . with the balloon 212 expanded , a fluid introduced via the distal end 235 can only travel to the distal side of balloon 212 . when used with a contrast agent , the inflated balloon 210 will result in sharp line on the fluoroscope detailing the exact location of the catheter end . this method will also be useful if the catheter is inserted against the normal flow of fluid in the lumen , e . g ., blood flow . an interventional catheter 290 may then be introduced , as shown in fig4 c , while being imaged by an external modality . in addition , intraluminal images can be obtained with the imaging element 210 to ensure positioning of the delivery catheter throughout the procedure . the methods of the invention can also be used with various interventional devices , such as catheters . various interventional catheters are described in u . s . pat . nos . 8 , 187 , 267 , 7 , 993 , 333 , 7 , 981 , 151 , 8 , 080 , 800 , and 6 , 544 , 217 . as discussed , imaging elements of the invention may be placed on an outer catheter body / shaft or within a catheter body / shaft . the imaging element may have any suitable configuration for imaging a vessel surface . in certain embodiments , the imaging element is a ring transducer array wrapped around a distal end of the catheter shaft . this configuration allows one to image a cross - section of the vessel without having to rotate the catheter shaft . in certain embodiments , the imaging elements of the array are transducers , such as ultrasound transducers , piezoelectric micromachined ultrasound transducers , capacitive micromachined ultrasound transducers , and photo - acoustic transducers . each imaging elements of the array may include a signal transmitter and a signal collector ( or image collector ). the signal transducer and the signal collector may be the same or different . for example , a piezoelectric element that is used to transmit a signal may also be used to receive a signal . ultrasound transducers produce ultrasound energy and receive echoes from which real time ultrasound images of a thin section of the blood vessel are produced . the transducers in the array may be constructed from piezoelectric components that produce sound energy at 20 - 50 mhz . in yet another embodiment , the imaging element is an optical acoustic imaging element . optical - acoustic imaging elements include at least one acoustic - to - optical transducer . in certain embodiments , the acoustic - to - optical transducer is a fiber bragg grating within an optical fiber . the imaging element may one or more optical fibers with fiber bragg gratings placed longitudinally along a length of the catheter shaft . for example , the imaging element may include two or more optical fibers aligned next to each other , and each with a plurality of fiber bragg gratings . in another embodiment , an optical fiber having several fiber bragg gratings may be wrapped around the distal end of the catheter . in some embodiments , the imaging elements may include an optical fiber with one or more fiber bragg gratings ( acoustic - to - optical transducer ) and one or more other transducers . the at least one other transducer may be used to generate the acoustic energy for imaging . acoustic generating transducers can be electric - to - acoustic transducers or optical - to - acoustic transducers . fiber bragg gratings for imaging provides a means for measuring the interference between two paths taken by an optical beam . a partially - reflecting fiber bragg grating is used to split the incident beam of light into two parts , in which one part of the beam travels along a path that is kept constant ( constant path ) and another part travels a path for detecting a change ( change path ). the paths are then combined to detect any interferences in the beam . if the paths are identical , then the two paths combine to form the original beam . if the paths are different , then the two parts will add or subtract from each other and form an interference . the fiber bragg grating elements are thus able to sense a change wavelength between the constant path and the change path based on received ultrasound or acoustic energy . the detected optical signal interferences can be used to generate an image using any conventional means . exemplary optical - acoustic imaging elements are disclosed in more detail in u . s . pat . nos . 6 , 659 , 957 and 7 , 527 , 594 , 7 , 245 . 789 , 7447 , 388 , 7 , 660 , 492 , 8 , 059 , 923 and in u . s . patent publication nos . 2008 / 0119739 , 2010 / 0087732 and 2012 / 0108943 . in another embodiment , the imaging element of the invention is a capacitive micromachined ultrasound transducer array ( cmut ). cmut elements generally include at least a pair of electrodes separated by a uniform air or vacuum gap , with the upper electrode suspended on a flexible membrane . impinging acoustic signals cause the membrane to deflect , resulting in capacitive changes between the electrodes , which produce electronic signals usable for ultrasonic imaging . exemplary cmut arrays are described in more detail in u . s . pat . nos . 8 , 309 , 428 and 6 , 328 , 696 , and u . s . publication no . 2007 / 0161896 . in another embodiment , the imaging element of the invention is a piezoelectric micromachined ultrasound transducer array ( pmut ). in pmuts the sound - radiating element is a micromachined multi - layer membrane that is activated by a piezoactive layer ( such as a pzt thin film ). the pzt thin film is poled in the thickness direction . application of an electric field across the thickness direction causes a strain in the film and induces membrane bending , thereby propagating a sound wave . reflected sound waves are received on the membrane , which causes a detectable charge displacement in the electrode pzt . pmut arrays are described in more detail in u . s . pat . no . 8 , 148 , 877 , u . s . publication no . 2003 / 0085635 , and akasheh , firas , et al . “ development of piezoelectric micromachined ultrasonic transducers .” sensors and actuators a : physical 111 . 2 ( 2004 ): 275 - 287 . while the invention is described as delivering fluids , e . g ., contrast , to the vasculature and or delivering interventional catheters , it is understood that similar methods could be used to deliver fluids to a number of tissues that are accessible via the various lumen of the body , including , but not limited to vasculature of the lymphatic and nervous systems , various structures of the gastrointestinal tract including lumen of the small intestine , large intestine , stomach , esophagus , colon , pancreatic duct , bile duct , hepatic duct , lumen of the reproductive tract including the vas deferens , uterus and fallopian tubes , structures of the urinary tract including urinary collecting ducts , renal tubules , urethra , and bladder , and structures of the head and neck and pulmonary system including sinuses , parotid , trachea , bronchi , and lungs . in some embodiments , a catheter of the invention includes imaging element that sends and receives imaging data through the operation of ivus , or other imaging hardware . in some embodiments , a catheter of the invention is coupled to a processing device . a processing device of the invention is a computer device such as a laptop , desktop , or tablet computer , and obtains a three - dimensional data set by retrieving it from a tangible storage medium , such as a disk drive on a server using a network or as an email attachment . methods of the invention can be performed using software , hardware , firmware , hardwiring , or combinations of any of these . features implementing functions can also be physically located at various positions , including being distributed such that portions of functions are implemented at different physical locations ( e . g ., imaging apparatus in one room and host workstation in another , or in separate buildings , for example , with wireless or wired connections ). in some embodiments , a user interacts with a visual interface to view images from the imaging system . input from a user ( e . g ., parameters or a selection ) are received by a processor in an electronic device ( such as a computer 449 ). the selection can be rendered into a visible display . an exemplary imaging system is illustrated in fig5 . as shown in fig5 , an imaging engine 859 of the imaging assembly communicates with host workstation 433 as well as optionally server 413 over network 409 . the data acquisition element 855 ( daq ) of the imaging engine receives imaging data from one or more imaging element . in some embodiments , an operator uses computer 449 or terminal 467 to control system 400 or to receive images . an image may be displayed using an i / o 454 , 437 , or 471 , which may include a monitor . any i / o may include a keyboard , mouse or touchscreen to communicate with any of processor 421 , 459 , 441 , or 475 , for example , to cause data to be stored in any tangible , nontransitory memory 463 , 445 , 479 , or 429 . server 413 generally includes an interface module 425 to effectuate communication over network 409 or write data to data file 417 . processors suitable for the execution of computer program include , by way of example , both general and special purpose microprocessors , and any one or more processor of any kind of digital computer . generally , a processor will receive instructions and data from a read - only memory or a random access memory or both . the essential elements of computer are a processor for executing instructions and one or more memory devices for storing instructions and data . generally , a computer will also include , or be operatively coupled to receive data from or transfer data to , or both , one or more mass storage devices for storing data , e . g ., magnetic , magneto - optical disks , or optical disks . information carriers suitable for embodying computer program instructions and data include all forms of non - volatile memory , including by way of example semiconductor memory devices , ( e . g ., eprom , eeprom , solid state drive ( ssd ), and flash memory devices ); magnetic disks , ( e . g ., internal hard disks or removable disks ); magneto - optical disks ; and optical disks ( e . g ., cd and dvd disks ). the processor and the memory can be supplemented by , or incorporated in , special purpose logic circuitry . to provide for interaction with a user , the subject matter described herein can be implemented on a computer having an i / o device , e . g ., a crt , lcd , led , or projection device for displaying information to the user and an input or output device such as a keyboard and a pointing device , ( e . g ., a mouse or a trackball ), by which the user can provide input to the computer . other kinds of devices can be used to provide for interaction with a user as well . for example , feedback provided to the user can be any form of sensory feedback , ( e . g ., visual feedback , auditory feedback , or tactile feedback ), and input from the user can be received in any form , including acoustic , speech , or tactile input . the subject matter described herein can be implemented in a computing system that includes a back - end component ( e . g ., a data server 413 ), a middleware component ( e . g ., an application server ), or a front - end component ( e . g ., a client computer 449 having a graphical user interface 454 or a web browser through which a user can interact with an implementation of the subject matter described herein ), or any combination of such back - end , middleware , and front - end components . the components of the system can be interconnected through network 409 by any form or medium of digital data communication , e . g ., a communication network . examples of communication networks include cell network ( e . g ., 3g or 4g ), a local area network ( lan ), and a wide area network ( wan ), e . g ., the internet . the subject matter described herein can be implemented as one or more computer program products , such as one or more computer programs tangibly embodied in an information carrier ( e . g ., in a non - transitory computer - readable medium ) for execution by , or to control the operation of , data processing apparatus ( e . g ., a programmable processor , a computer , or multiple computers ). a computer program ( also known as a program , software , software application , app , macro , or code ) can be written in any form of programming language , including compiled or interpreted languages ( e . g ., c , c ++, perl ), and it can be deployed in any form , including as a stand - alone program or as a module , component , subroutine , or other unit suitable for use in a computing environment . systems and methods of the invention can include instructions written in any suitable programming language known in the art , including , without limitation , c , c ++, perl , java , activex , html5 , visual basic , or javascript . a computer program does not necessarily correspond to a file . a program can be stored in a portion of file 417 that holds other programs or data , in a single file dedicated to the program in question , or in multiple coordinated files ( e . g ., files that store one or more modules , sub - programs , or portions of code ). a computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network . a file can be a digital file , for example , stored on a hard drive , ssd , cd , or other tangible , non - transitory medium . a file can be sent from one device to another over network 409 ( e . g ., as packets being sent from a server to a client , for example , through a network interface card , modem , wireless card , or similar ). writing a file according to the invention involves transforming a tangible , non - transitory computer - readable medium , for example , by adding , removing , or rearranging particles ( e . g ., with a net charge or dipole moment into patterns of magnetization by read / write heads ), the patterns then representing new collocations of information about objective physical phenomena desired by , and useful to , the user . in some embodiments , writing involves a physical transformation of material in tangible , non - transitory computer readable media ( e . g ., with certain optical properties so that optical read / write devices can then read the new and useful collocation of information , e . g ., burning a cd - rom ). in some embodiments , writing a file includes transforming a physical flash memory apparatus such as nand flash memory device and storing information by transforming physical elements in an array of memory cells made from floating - gate transistors . methods of writing a file are well - known in the art and , for example , can be invoked manually or automatically by a program or by a save command from software or a write command from a programming language . references and citations to other documents , such as patents , patent applications , patent publications , journals , books , papers , web contents , have been made throughout this disclosure . all such documents are hereby incorporated herein by reference in their entirety for all purposes . the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof . the foregoing embodiments are therefore to be considered in all respects illustrative rather than limiting on the invention described herein . scope of the invention is thus indicated by the appended claims rather than by the foregoing description , and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein
the invention is a delivery catheter , e . g ., a guide catheter , having an imaging element in proximity to the distal end of the catheter . catheters of the invention are able to placement of the catheter in proximity to an ostium , thereby increasing the efficiency of contrast delivery while reducing the risk of ischemia due to blocked blood supply . the invention additionally assists in maintaining catheter position during delivery of a fluid from the catheter , resulting in better performance with less fluid . for example , a catheter of the invention can be used to produce improved fluoroscopic images with less overall contrast . this improvement reduces the risk of an allergic reaction to the contrast while decreasing the length of time for a procedure , i . e ., because of a need to re - contrast .