Patent Publication Number: US-2022233055-A1

Title: Endoscopic imaging system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 10/406,149, filed Apr. 1, 2003, the disclosure of which is expressly incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to medical devices in general and therapeutic and diagnostic endoscopes in particular. 
     BACKGROUND OF THE INVENTION 
     As an aid to the early detection of disease, it has become well established that there are major public health benefits from regular endoscopic examinations of internal structures such as the esophagus, lungs, colon, uterus, and other organ systems. A conventional imaging endoscope used for such procedures comprises a flexible tube with a fiber optic light guide that directs illuminating light from an external light source through a lens at the distal end of the endoscope which focuses the illumination on the tissue to be examined. An objective lens and fiber optic imaging light guide communicating with a camera at the proximal end of the scope, or an imaging camera chip at the distal tip, transmit an image to the examiner. In addition, most endoscopes include one or more working channels through which medical devices such as biopsy forceps, snares, fulguration probes, and other tools may be passed. 
     Navigation of the endoscope through complex and tortuous paths is critical to success of the examination with minimum pain, side effects, risk or sedation to the patient. To this end, modern endoscopes include means for deflecting the distal tip of the scope to follow the pathway of the structure under examination, with minimum deflection or friction force upon the surrounding tissue. Control cables similar to puppet strings are carried within the endoscope body and connect a flexible portion of the distal end to a set of control knobs at the proximal endoscope handle. By manipulating the control knobs, the examiner is usually able to steer the endoscope during insertion and direct it to the region of interest, in spite of the limitations of such traditional control systems, which are clumsy, non-intuitive, and friction-limited. Common operator complaints about traditional endoscopes include their limited flexibility, limited column strength, and limited operator control of stiffness along the scope length. 
     Conventional endoscopes are expensive medical devices costing in the range of $25,000 for an endoscope, and much more for the associated operator console. Because of the expense, these endoscopes are built to withstand repeated disinfections and use upon many patients. Conventional endoscopes are generally built of sturdy materials, which decreases the flexibility of the scope and thus can decrease patient comfort. Furthermore, conventional endoscopes are complex and fragile instruments which can frequently need expensive repair as a result of damage during use or during a disinfection procedure. To overcome these and other problems, there is a need for a low cost imaging endoscope that can be used for a single procedure and thrown away. The scope should have better navigation and tracking, a superior interface with the operator, improved access by reduced frictional forces upon the lumenal tissue, increased patient comfort, and greater clinical productivity and patient throughput than those that are currently available. 
     SUMMARY OF THE INVENTION 
     To address these and other problems in the prior art, the present invention is an endoscopic video imaging system. The system includes a motion control cabinet that includes a number of actuators that control the orientation of an endoscope and an imaging system to produce images of tissue collected by an image sensor at the distal end of the endoscope. A single use endoscope is connectable with the control cabinet and used to examine a patient. After the examination procedure, the endoscope is disconnected and disposed of. 
     The endoscope of the present invention includes a flexible elongate tube or shaft and an illumination source that directs light onto a tissue sample. An image sensor and objective lens at or adjacent the distal end of the endoscope captures reflected light to produce an image of the illuminated tissue. Images produced by the sensor are transmitted to a display device to be viewed by an examiner. In one embodiment, the illumination source comprises one or more light emitting diodes (LEDs) and the image sensor comprises a CMOS solid state image sensor. 
     The endoscope of the present invention also includes a steering mechanism such as a number of tensile control cables, which allow the distal end of the endoscope to be deflected in a desired direction. In one embodiment of the invention, a proximal end of the tensile control cables communicates with actuators within the control cabinet. A freestanding joystick controller generates electrical control signals which the control cabinet uses to compute signals to drive the actuators that orient the distal end of the endoscope in the direction desired by the examiner. In another embodiment of the invention, the distal end of the endoscope is automatically steered, or provided to the examiner, based on analysis of images from the image sensor. 
     In one embodiment of the invention, the endoscope includes a polymeric articulation joint adjacent its distal end that aids in bending the distal end of the scope in a desired direction. The articulation joint is constructed as a number of live hinges integrated into a unified structure of the required overall properties and dimensions. Tension of the control cables causes the live hinges of the articulation joint to deflect, thereby bending the distal tip of the endoscope. In one embodiment of the invention, the articulation joint exerts a restoring force such that upon release of a tensioning force, the distal end of the scope will straighten. 
     In an alternative embodiment, the articulation joint comprises a number of stacked discs that rotate with respect to one another. Control cables pass through the discs and pull adjacent discs together to turn the distal end of the endoscope. 
     In another embodiment of the invention, the endoscope has a variation in stiffness along its length that allows the distal end to be relatively flexible while the more proximal regions of the scope have increased column strength and torque fidelity so that a physician can twist and advance the endoscope with greater ease and accuracy and with fewer false advances (“loops”). Variation in stiffness along the length can be provided by varying the durometer of materials that comprise a shaft of the endoscope. Operator-controlled, variable stiffness can be provided by control cables that can be tightened or loosened to adjust the stiffness of the shaft. In yet another embodiment, the spacing between the live hinges of the articulation joint is selected to provide a variation in stiffness along the length of the articulation joint. 
     In yet another embodiment of the invention, the endoscope is covered with a retractable sleeve that uncovers the distal end of the scope during use and extends over the distal end after the scope is removed from a patient. 
     In another embodiment of the invention, the scope is coated with a hydrophilic coating to reduce its coefficient of friction. 
     In another embodiment of the invention, the scope is retractable in a longitudinal direction. The distal end of the scope is extendable using a spring, pull wires, bellows or the like to allow a physician to move the distal tip without having to alter the position of the shaft of the endoscope. 
     In yet another embodiment of the invention, the endoscope includes a heat dissipating mechanism for removing heat produced by the illumination source and image sensor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
         FIGS. 1A and 1B  illustrate two possible embodiments of an endoscopic video imaging system in accordance with the present invention; 
         FIG. 2  illustrates further detail of an endoscope used in the imaging system shown in  FIG. 1A ; 
         FIG. 3A  is a block diagram of a motion control cabinet that interfaces with an imaging endoscope in accordance with one embodiment of the present invention; 
         FIG. 3B  is a block diagram of a motion control cabinet that interfaces with an imaging endoscope in accordance with another embodiment of the present invention; 
         FIGS. 4A-4D  illustrate one mechanism for connecting the vision endoscope to a motion control cabinet; 
         FIG. 5  is a detailed view of one embodiment of a handheld controller for controlling an imaging endoscope; 
         FIG. 6  illustrates one embodiment of a distal tip of an imaging endoscope in accordance with the present invention; 
         FIG. 7  illustrates one mechanism for terminating a number of control cables in a distal tip of an imaging endoscope; 
         FIG. 8  illustrates an imaging endoscope having control cables routed through lumens in the walls of an endoscope shaft; 
         FIGS. 9A and 9B  illustrate a transition guide that routes control cables from a central lumen of an endoscope shaft to lumens in an articulation joint; 
         FIGS. 10A and 10B  illustrate the construction of a shaft portion of an endoscope in accordance with one embodiment of the present invention; 
         FIG. 11  illustrates one mechanism for providing a shaft having a varying stiffness along its length; 
         FIGS. 12A and 12B  illustrate an extrusion used to make an articulation joint in accordance with one embodiment of the present invention; 
         FIG. 13  illustrates an articulation joint in accordance with one embodiment of the present invention; 
         FIGS. 14 and 15  illustrate an extrusion having areas of a different durometer that is used to form an articulation joint in accordance with another embodiment of the present invention; 
         FIGS. 16A and 16B  illustrate another embodiment of an articulation joint including a number of ball and socket sections; 
         FIGS. 17A-17D  illustrate various possible configurations of ball and socket sections used to construct an articulation joint; 
         FIGS. 18A-18B  illustrate an articulation joint formed of a number of stacked discs in accordance with another embodiment of the present invention; 
         FIGS. 19A-19B  illustrate a disc used to form an articulation joint in accordance with another embodiment of the present invention; 
         FIGS. 20A-20B  illustrate a disc used to form an articulation joint in accordance with another embodiment of the present invention; 
         FIGS. 21A-21B  illustrate a non-circular segment used to form an articulation joint in accordance with another embodiment of the present invention; 
         FIG. 22  illustrates an endoscope having a braided member as an articulation joint in accordance with another embodiment of the present invention; 
         FIG. 23  illustrates one possible technique for securing the ends of a control wire to a braided articulation joint; 
         FIG. 24  illustrates a shaft having one or more memory reducing wraps in accordance with another embodiment of the present invention; 
         FIG. 25  illustrates a shaft including longitudinal stripes of a high durometer material in accordance with another embodiment of the present invention; 
         FIGS. 26-29  illustrate alternative embodiments of a gripping mechanism that rotates an imaging endoscope shaft in accordance with the present invention; 
         FIGS. 30A and 30B  illustrate a retractable sleeve used with another embodiment of the present invention; 
         FIG. 31  illustrates one embodiment of a heat dissipating distal tip of an endoscope in accordance with the present invention; and 
         FIGS. 32 and 33  illustrate alternative embodiments of a heat dissipating distal tip in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As indicated above, the present invention is an endoscopic video imaging system that allows a physician to view internal body cavities of a patient as well as to insert surgical instruments into the patient&#39;s body. An imaging endoscope used with the present invention is sufficiently inexpensive to manufacture such that the endoscope can be considered a disposable item. 
     As shown in  FIG. 1A , an endoscopic video imaging system  10  according to one embodiment of the present invention includes an imaging endoscope  20 , a motion control cabinet  50  and a handheld controller  80 . The imaging endoscope  20  has a distal tip  22  that is advanced into a patient&#39;s body cavity and a proximal end  24  that is connected to the motion control cabinet  50 . As will be explained in further detail below, the motion control cabinet  50  includes a number of actuators that control a steering mechanism within the endoscope in order to change the orientation of the distal tip  22 . A physician or their assistant uses the handheld controller  80  to input control signals that move the distal tip  22  of the imaging endoscope  20 . In addition, the motion control cabinet  50  may include connections to sources of air/gas and a flushing liquid such as water for clearing the imaging endoscope. The motion control cabinet  50  also includes imaging electronics to create and/or transfer images received from an image sensor to a video display for viewing by a physician or technician. 
     In the embodiment shown, the imaging endoscope  20  also includes a breakout box  26  that is positioned approximately midway along the length of the endoscope. The breakout box  26  provides an attachment point for a vacuum bottle  40  that collects liquids from a lumen within the imaging endoscope. The vacuum bottle  40  is controlled by a vacuum valve  28  that is positioned on the breakout box  26 . Alternatively, the valve can be positioned within the motion control cabinet  50  and controlled from the handheld controller  80 . 
     If desired, the handheld controller  80  can be secured to the breakout box  26  such that the two units can be moved as one if desired. Upon completion of a patient examination procedure, the imaging endoscope  20  is disconnected from the motion control cabinet  50  and disposed of. A new imaging endoscope  20  is then connected to the motion control cabinet  50  for the next examination procedure to be performed. 
     The embodiment shown in  FIG. 1A  is a “parallel” configuration whereby the endoscope  20  and handheld controller  80  are separately plugged into different connectors of the motion control cabinet  50 . This parallel configuration allows one operator to handle the endoscope while another operator can handle the handheld controller  80 . Alternatively, the handheld controller  80  may be secured to the endoscope  20  such that a single operator can control both.  FIG. 1B  illustrates a “serial” configuration of the invention. Here, the imaging endoscope  20  is connected to the motion control cabinet  50  through the handheld controller  80 . 
       FIG. 2  shows further detail of one embodiment of the imaging endoscope  20 . At the proximal end of the endoscope is a low torque shaft  24  and a connector  34  that connects the endoscope  20  to the motion control cabinet  50 . Distal to the breakout box  26  is a higher torque shaft. At the distal end of the endoscope  20  is the distal tip  22  that includes a light illumination port, an image sensor, an entrance to a working lumen and a flushing lumen (not shown). Proximal to the distal tip  22  is an articulation joint  30  that provides sufficient flexibility to the distal section of the shaft such that the distal tip  22  can be directed over an angle of 180 degrees by the steering mechanism. 
     As discussed above, the endoscope  20 , in accordance with one embodiment of the invention, has a higher torque shaft at the distal section of the endoscope and a lower torque shaft at its proximal end. The breakout box  26  positioned along the length of the endoscope shaft can be used as a handle or gripper to impart rotation of the distal end of the endoscope during a medical examination procedure. The higher torque portion of the shaft transfers rotational motion that is imparted at a location proximal to the distal tip in order to guide the distal tip of the imaging catheter. The low torque shaft portion of the imaging catheter does not transfer torque as well and can twist when rotational motion is applied. 
     In use, the physician can insert a medical device such as a biopsy forceps, snare, etc., into a connector  32  found on the breakout box  26  that leads to a working channel lumen in the endoscope. In alternate embodiments, the entrance to the working channel lumen may be positioned further towards the proximal end of the endoscope. 
       FIG. 3A  is a block diagram of the major components included within one embodiment of the motion control cabinet  50 . The motion control cabinet is preferably positioned on a cart that is wheeled near a patient prior to an examination procedure. The motion control cabinet is connected to a source of electrical power, either A.C. mains or a battery, as well as to a source of insufflation gas and irrigation liquid. Inside the motion control cabinet  50  is a controller interface  52  that is connected to the handheld controller  80  and receives control signals therefrom. To change the orientation of the distal tip of the imaging endoscope, the control signals are received from a directional switch in the handheld controller  80 . The control signals are supplied to a servo motor controller  54  that in turn controls a number of actuators, such as servo motors  56   a ,  56   b ,  56   c ,  56   d . Each of the servo motors  56   a - 56   d  is connected to one or more control cables within the imaging endoscope. Motion of the servo motors  56   a - 56   d  pulls or releases the control cables in order to change the orientation of the distal tip  22  of the imaging endoscope  20 . Although the embodiment shown in  FIG. 3A  shows four servo motors and control cables, it will be appreciated that fewer or more servo motors and corresponding control cables could be used to move the distal tip. For example, some imaging endoscopes may use three control cables and three associated servo motors. 
     Also included in the motion control cabinet  50  is a power source  58  that provides electrical power to a light source such as a number of light emitting diodes (LEDs) at the distal end  22  of the imaging endoscope. Alternatively, if the imaging catheter utilizes an external light source, then the motion control cabinet can include a high intensity light source such as a laser or Xenon white light source that supplies light to a fiber optic illumination guide within the imaging endoscope  20  in order to illuminate an internal body organ. The power source  58  may be controlled by control signals received from the handheld controller  80  when the user desires to activate the light source. 
     An imaging electronics board  60  captures images received from an image sensor (not shown) at the distal end of the imaging endoscope. The imaging electronics board  60  can enhance the images received or can provide video effects such as zoom, color changes, highlighting, etc., prior to display of the images on a video display (not shown). Images of the tissue may also be analyzed by the imaging electronics board  60  to produce control signals that are supplied to the servo motor controller  54  in order to automatically steer the distal tip of the endoscope as will be discussed in further detail below. Images produced by the imaging electronics board  60  may also be printed on a digital printer, saved to a computer readable media such as a floppy disk, CD, DVD, etc., or a video tape for later retrieval and analysis by a physician. 
     Finally, the motion control cabinet  50  includes valves  70  that control the delivery of insufflation air/gas to insufflate a patient&#39;s body cavity and an irrigation liquid to flush out a body cavity and/or clean the imaging light source and image sensor at the distal end of the endoscope. The insufflation air/gas and irrigation liquid are connected to the imaging catheter via a connector  38  that connects to an irrigation/insufflation lumen of the imaging endoscope  20 . In one embodiment of the invention, the irrigation and insufflation lumen are the same lumen in the imaging catheter. However, it will be appreciated that separate irrigation and insufflation lumens could be provided if desired and if space in the endoscope permits. 
       FIG. 3B  illustrates another embodiment of a motion control cabinet  50 A that is similar to the cabinet shown in  FIG. 3A . The motion control cabinet  50 A includes a vacuum valve  71  that controls vacuum delivered to a vacuum collection bottle  40 . A vacuum line  73  connects to a vacuum lumen within the imaging endoscope  20 . The vacuum valve  71  is controlled from the handheld controller  80 . 
       FIGS. 4A-4D  illustrate one mechanism for securing the proximal end of the imaging endoscope to the control cabinet  50  prior to performing an endoscopic examination. The control cabinet  50  includes a connector  34 A having a number of shafts  57  that are driven by the servo motors  56  shown in  FIGS. 3A and 3B . Each shaft  57  is shaped to be received in a corresponding spool on which the control cables are wound. Also included in the connector  34 A are connections to the insufflation and irrigation valves  70  and vacuum valve  71  to provide air, water and vacuum to the endoscope. 
       FIGS. 4A and 4B  illustrate one possible connector  34  found at the proximal end of the endoscope  20  for securing the endoscope to the motion control cabinet  50 . The connector  34  includes a number of thumbscrews  77  or other quick release mechanisms that allow the connector  34  to be easily secured to the connector  34 A on the motion control cabinet. As shown in  FIG. 4C , the connector  34 A includes a number of spools  79  about which the control cables are wound. Each spool is preferably threaded or grooved to prevent the control cables from binding on the spool during use. A cover may surround a portion of the spool to keep the control cables against the spool and to aid in supporting the spool within the connector  34 . In one embodiment of the invention, the spools are prevented from rotating when the connector is not engaged with the motion control cabinet  50  by brakes  81  having pins that fit within corresponding slots in the spool. Once the connector  34  is mounted to the motion control cabinet  50 , the brakes  81  are disengaged from the spool such that the spool can be moved by the servo motors. Electrical connections for the light source and image sensor as well as connections to the air and water valves can be found on the sides of the connector or on the rear face of the connector  34  to engage the valves, as shown in  FIG. 4A . 
       FIG. 4D  illustrates a cross-sectional view of a shaft  57  fitted within a spool  79 . The shaft  57  is supported by a cylinder  59  having a spring  61  therein such that the shaft  57  is free to move within the cylinder  59 . The cylinder  59  is directly coupled to the servo motors within the motion control cabinet. The spring  61  allows the shaft  57  to float such that the shaft can more easily align and engage the mating surface of the spool  79 . 
     Upon insertion of the shaft  57  into the spool  79 , the brake  81  is released, thereby allowing the spool  79  to be moved by rotation of the cylinder  59 . In some instances, the brake  81  may be omitted, thereby allowing the spools  79  to freely rotate when the connector  34  is not engaged with the motion control cabinet  50 . 
       FIG. 5  illustrates various controls located on the handheld controller  80  in accordance with one embodiment of the invention. The handheld controller  80  includes a controller body  82  that, in the parallel embodiment of the invention, is coupled to the motion control cabinet  50  by an electrical cord  84 , a wireless radio frequency channel, an infrared or other optical link. If the connection is made with an electrical cord, a strain relief  86  is positioned at the junction of the electrical cord  84  and the body  82  of the controller to limit the bending of the electrical wires within the electrical cord  84 . In the serial embodiment of the invention, the connection of the handheld controller  80  to the motion control cabinet  50  is made with a conductor that includes both the wires to transmit signals to the motion controllers and imaging systems, as well as a lumens to carry the insufflation air/gas and irrigation liquid. In addition, the control cables of the endoscope engage cables connected to the actuators in the motion control cabinet through the handheld controller  80 . 
     Positioned in an ergonomic arrangement on the handheld controller  80  are a number of electrical switches. An articulation joystick  88  or other multi-positional device can be moved in a number of positions to allow the physician to orient the distal tip of the imaging endoscope in a desired direction. In order to guide the imaging endoscope manually, the physician moves the joystick  88  while watching an image on a video monitor or by viewing the position of the distal tip with another medial imaging technique such as fluoroscopy. As the distal tip of the endoscope is steered by moving the joystick  88  in the desired direction, the physician can push, pull and/or twist the endoscope to guide the distal tip in the desired direction. 
     A camera button  90  is provided to capture an image of an internal body cavity or organ in which the imaging endoscope  20  is placed. The images collected may be still images or video images. The images may be adjusted for contrast or otherwise enhanced prior to display or storage on a recordable media. 
     An irrigation button  92  activates an irrigation source to supply a liquid such as water through an irrigation lumen of the imaging endoscope. The liquid serves to clean an image sensor and the light source at the distal end of the endoscope as well as an area of the body cavity. An insufflation button  94  is provided to activate the insufflation source within the motion control cabinet  50  to supply air/gas through a lumen of the catheter. The supply of the insufflation gas expands portions of the body cavity around the distal tip of the endoscope so that the physician can more easily advance the endoscope or better see the tissue in front of the endoscope. 
     In one embodiment of the invention, the handle  82  also includes a thumb screw  96  for securing the handheld controller  80  to the breakout box  26  as indicated above. A corresponding set of threads on a breakout box  26  receive the thumb screw  96  in order to join the two parts together. One or more additional buttons  98  may also be provided to activate additional functions such as recording or printing images, adjusting light intensity, activating a vacuum control valve, etc., if desired. 
     The endoscope of the present invention may also be steered automatically. Images received by the imaging electronics  60  are analyzed by a programmed processor to determine a desired direction or orientation of the distal tip of the endoscope. In the case of a colonoscopy, where the endoscope is advanced to the cecum, the processor controls the delivery of insufflation air/gas to inflate the colon, the processor then analyzes the image of the colon for a dark spot that generally marks the direction in which the scope is to be advanced. The processor then supplies control instructions to the servo controller  54  such that the distal tip is oriented in the direction of the dark spot located. 
     In other modes, a processor in the motion control cabinet causes the distal tip of the endoscope to move in a predefined pattern. For example, as the scope is being withdrawn, the distal tip may be caused to move in a search pattern such that all areas of a body cavity are scanned for the presence of disease. By using the automatic control of the distal tip, a physician only has to advance or retract the scope to perform an examination. 
     As will be described in further detail below, the imaging endoscope  20  generally comprises a hollow shaft having one or more lumens formed of polyethylene tubes which terminate at the distal tip  22 . As shown in  FIG. 6 , one embodiment of a distal tip  110  comprises a cylinder having a distal section  112  and a proximal section  114 . The proximal section  114  has a smaller diameter than the diameter of the distal section  112  in order to form a stepped shoulder region. The diameter of the shoulder is selected that shaft walls of the endoscope can seat on the shoulder region to form a smooth outer surface with the distal section  112 . The distal face of the distal tip  110  includes a number of ports, including a camera port  116 , one or more illumination ports  118 , an access port or working channel lumen  120 , and a directional flush port  122 . 
     Fitted within the camera port  116  is an image sensor (not shown) that preferably comprises a CMOS imaging sensor or other solid state device and one or more glass or polymeric lenses that produce electronic signals representative of an image of the tissue in front of the camera port  116 . The image sensor is preferably a low light sensitive, low noise video VGA, CMOS, color imager or higher resolution sensor such as SVGA, SXGA, or XGA. The video output of the sensor may be in any conventional format including PAL, NTSC or high definition video format. 
     The illumination port  118  houses one or more lenses and one or more light emitting diodes (LEDs) (not shown). The LEDs may be high intensity white light sources or may comprise colored light sources such as red, green and blue LEDs. With colored LEDs, images in different spectral bands may be obtained due to illumination with any one or more individual colors. White light images may be obtained by the simultaneous or sequential illumination of the colored LEDs and combining individual color images. As an alternative to LEDs, the light source may be external to the endoscope and the illumination light delivered to the illumination port with a fiber optic bundle. 
     The access port  120  is the termination point of the working channel or lumen of the endoscope  20 . In the embodiment described above, the proximal end of the working channel terminates at the breakout box  26  as shown in  FIG. 2 . However, the working channel could terminate nearer the proximal end of the imaging catheter. 
     The directional flush port  122  includes a cap  124  that directs liquid supplied through an irrigation and insufflation lumen across the front face of the distal tip  110  in the direction of the camera port  116  and/or the illumination port  118 . The cap  124  thereby serves to clean the camera port  116  and the illumination port  118  for a better view of the internal body cavity in which the imaging catheter is placed. In addition, the flushing liquid cleans an area of tissue surrounding the distal end of the endoscope. 
       FIG. 7  shows further detail of one embodiment of a distal tip  110  of the imaging endoscope. In this embodiment, the tip section  110  includes a number of counter bored holes  126  that are positioned around the circumference of the distal tip  110 . The counter bored holes  126  receive swaged or flanged ends of the control cables that orient the distal tip. Tension on the control cables pull the distal tip  110  in the direction of the tensioning force. 
       FIG. 8  is a lengthwise, cross-sectional view of an imaging endoscope  20  in accordance with one embodiment of the present invention. The distal tip  110  is adhesively secured, welded or otherwise bonded within a center lumen at the distal end of the articulation joint  30 . Secured to the proximal end of the articulation joint  30  is a distal end of a shaft  128 . As discussed above, the shaft  128  is preferably stiffer or better able to transmit torque towards the distal end of the endoscope than at the proximal end of the endoscope. 
     The control cables  130  that move the distal tip of the endoscope are preferably made of a non-stretching material such as stainless steel or a highly oriented polyethylene-theralate (PET) string. The control cables may be routed within a center lumen of the shaft  128  or, as shown in  FIG. 8 , may be routed through lumens formed within the walls of the shaft. The control cables  130  extend through guides within the walls of articulation joint  30  and terminate either at the distal end of the articulation joint  30  or in the distal tip section  110 . 
     If the control cables are routed through the center lumen of the shaft  128 , the cables are preferably carried in stainless steel or plastic spiral wrapped lumens to prevent binding and a transition guide  140  such as that as shown in  FIGS. 9A and 9B  may be used to guide the control cables into the proximal end of the articulation joint. The transition guide  140  has a proximal end  142  that is secured within a lumen of the distal end of the shaft. A central body portion  144  of the transition guide  140  has a diameter equal to the outer diameter of the imaging endoscope. In addition, the body portion  144  includes a number of diagonal lumens  148  that extend from a center lumen of the proximal end  142  to an outer surface of a stepped distal end  146  of the transition guide. The distal end  146  is secured within a proximal end of the articulation joint  30 . Control cables in the diagonally extending lumens  148  are therefore guided to the outer edge of the catheter where they extend through the guides or control cable lumens of the articulation joint  30 . 
       FIGS. 10A, 10B  illustrate one embodiment of a shaft that comprises the imaging endoscope  20 . The shaft  160  has a cover  162  that may include a wire or other braid  164  embedded therein. The braid  164 , if present, allows the torque characteristics of the shaft to be adjusted. The cover  162  may be formed by placing a sleeve over a mandrel. The braid  164  is placed over the sleeve and the mandrel is dipped into or sprayed with a coating material. Preferably the sleeve and coating material are made of polyurethane or other biocompatible materials such as polyethylene, polypropylene or polyvinyl alcohol. In addition, the interior lumen(s) and exterior of the shaft can be coated with a extrudable, hydrophilic, lubricious coating such as the HYDROPASS™ hydrophilic coating available from Boston Scientific, of Natick, Mass., and described in U.S. Pat. Nos. 5,702,754 and 6,048,620 which are herein incorporated by reference. 
     A plastic spiral wrap  166  such as spiral wire wrap available from Panduit Inc. is inserted into a lumen of the cover  162 . The spiral wrap  166  prevents the shaft  160  from crushing as it is bent around a patient&#39;s anatomy. 
     In one embodiment of the shaft  160 , the spiral wrap has a thickness of 0.060 inches and a pitch of 3/16 inch. However, it will be appreciated that other thicknesses of spiral wrap with a different pitch could be used to provide the desired column strength and bend modulus as well as to prevent kinking. 
       FIG. 11  shows one method of altering the torque fidelity of the distal and proximal portions of the shaft. The shaft  160  has a flexible section  170  that is proximal to the break out box and a stiffer section  172  that is distal to the break out box. The portion of the scope that is distal to the break out box has an increasing flexibility toward the distal tip and conversely a higher torque fidelity and column strength proximally. To increase the torque fidelity characteristics of the distal section  172  of the shaft, a braid  164  in that section includes two or more wires that are wound in opposite directions. In one embodiment, the wire braid has a pitch of 14-16 pik. However, the number of wires and their spacing can be adjusted as needed in order to tailor the torque fidelity of the shaft. 
     The proximal end  170  of the shaft  160  has a single spiral of wire  176  that is preferably wound in the same direction as the plastic spiral wrap  166  in the center lumen of the shaft  160 . Again, the torque fidelity of the proximal end of the shaft  170  can be adjusted by adjusting the pitch and/or direction of the wire  176  and its flexibility. 
     As will be appreciated, the single wire spiral  176  provides some torque fidelity but does have the same torque fidelity as the dual wire braid in the distal section of the shaft. The single wire spiral  176  may be omitted from the proximal portion of the shaft if even less torque fidelity is desired. 
     In order to facilitate steering the distal tip of imaging endoscope, the endoscope includes an articulation joint that allows the distal tip to be turned back on itself, i.e., over an arc of 180 degrees, by the control cables. As shown  FIG. 12A, 12B [,?] an articulation joint  200  is formed from a cylinder of a plastically deformable material having a central lumen  202 , and a number of control wire lumens  204  located in the walls of the articulation joint. If desired, the space between the control wire lumens in the cylinder wall may be thinner such that the control wire lumens form bosses that extend into the central lumen of the cylinder. The control cable lumens  204  are preferably oriented at 120° apart if three control cables are used or 90° apart if four control cables are used. 
     To facilitate bending of the articulation joint, the cylinder includes a number of live hinges  220  formed along its length. As can be seen in  FIG. 13 , each live hinge  220  comprises a pair of opposing V-shaped cuts  230  on either side of the cylinder and are separated by a flexible web  232  that forms the bendable portion of the hinge. In the embodiment designed for four control cables, each live hinge is oriented at 90 degrees with respect to an adjacent hinge. 
     Upon retraction of a control cable, those live hinges having webs  232  that are in line with the retracting control cable do not bend. Those live hinges having webs that are not in line with the control cable will be closed, thereby bending the articulation joint in the direction of the control cable under tension. 
     Another advantage of the articulation joint shown in  FIG. 13  is that the distal end of the scope can be retracted by pulling all the control cables simultaneously. This allows the physician to maneuver the distal tip in the body without having to move the remaining length of the endoscope. This may be useful when performing surgical procedures such as obtaining a biopsy or snaring polyps. 
     The articulation joint can be formed by extruding a cylinder with the central and control cable lumens in place and cutting the cylinder tube with a knife, laser, water jet, or other material removal mechanism to form the live hinges. Alternatively, the articulation joint can be molded with the live hinge joints in place. As will be appreciated, the angles of the V-shaped cuts that form the hinges may be uniform or may vary along the length of the articulation joint. Similarly, the distance between adjacent live hinges may be uniform or may vary in order to tailor the bending and torque fidelity characteristics of the articulation joint. In one embodiment of the invention, each live hinge has a closing angle of 30° so that six hinges are required to provide 180° of movement. The distal end of the articulation joint  200  may be counter-bored to receive the distal tip section  110  of the endoscope, as discussed above. Similarly, the proximal end of the articulation joint  200  is adapted to receive the distal end of the shaft of the endoscope. In the embodiment shown in  FIG. 13 , the control cable lumens  204  are aligned with the widest spacing of the live hinges and with the web portion of each hinge. However, it may be desirable to offset the control cable lumens  204  with respect to the hinges in order to lessen potential binding of the control cables in the hinge. As indicated above, the articulation joint should be made of a biocompatible material that will bend but will not collapse. Suitable materials include polyurethane, polyethylene, polypropylene, or other biocompatible polymers. 
     To prevent wear by the control cables as they are pulled by the actuation mechanism in the motion control cabinet, it may be desirable to produce the articulation joint from a material having areas of different durometers. As shown in  FIGS. 14 and 15 , a cylinder formed from an extruded tube  240  has alternating bands of a high durometer material  242  and a lower durometer material  244  around its circumference. The lumens  246  used to route the control cables are formed in the high durometer material to resist abrasion as the control cables are tensioned and released. In addition, the high durometer material also reduces friction between the control cables and the surrounding lumen.  FIG. 15  illustrates an articulation joint where the control cable lumens are offset with respect to the orientation of the web portions  248  of the live hinges so that the control cables do not pass through the web portion of the hinge. 
       FIGS. 16A, 16B  illustrate an alternative embodiment of an articulation joint. In this embodiment, the joint comprises a series of ball and socket connectors that are linked together. As shown in  FIG. 16A , each connector includes a socket section  290  and a ball section  292 . The ball section  292  fits in a socket section  290  of an adjacent connector. A lumen  294  extends axially through the ball section  292  to allow for passage of the wires that connect to the light source and the image sensor and tubes that carry irrigation fluids and insufflation gases. The ball and socket sections are preferably molded of a biocompatible polymer. 
     Each socket section can be formed with a fully formed ball section such as ball section  300  shown in  FIG. 17A . Alternatively, a partial ball section such as ball section  304  can be formed on a socket section  306  as shown in  FIG. 17B . To provide room for the control cables to move, the ball section can include slot  308  as shown in  FIGS. 17A, 17B  that cuts through the middle and sides of the ball section. Alternatively, a number of smaller slots  310  can be positioned around the circumference of the ball section as shown in  FIGS. 17C and 17D . The slots allow the control cables to be shortened under tension. A number of holes  312  at the interface of the ball section and socket section allows passage of the control cables from the socket section into the ball section as shown in  FIG. 17D . 
     In another embodiment of an articulation joint, the joint is made of a series of stacked discs that are positioned adjacent one another and move with respect to each other. As shown in  FIG. 18A , a disc  350  comprises an annular ring  352  having a pair of rearward facing rocker surfaces or cams  354  and a pair of forward facing rocker surfaces or cams  356 . The cams  354  are positioned 180° apart on the rear surface of the annular ring  352 , while the forward facing cams  356  are positioned 180 degrees apart on the forward face of the annular ring  352 . In the embodiment shown, the forward cams  356  are oriented at 90° with respect to the rear cams  354 . Opposite each cam on the other side of the annular ring is a flat land section so that the cams of an adjacent disc may engage with and rock on the flat section. Holes  360  are drilled through the annular ring and through the cams for passage of the control cables. Upon tension of the control cables, the discs will rock on the surface of the cams  354 ,  356  thereby bending the articulation joint in the desired direction. 
       FIG. 18B  shows an articulation joint made up of a series of stacked discs  350   a ,  350   b ,  350   c  . . . engaged with one another to form an articulation joint. A number of control cables  370   a ,  370   b ,  370   c ,  370   d , pass through the discs and are used to pull the discs on the cam surfaces to move the joint in the desired direction. 
       FIGS. 19A and 19B  show an alternative embodiment of the articulation joint shown in  FIGS. 18A and 18B . In this embodiment, an articulation joint comprises a series of stacked discs  380 , each comprising an annular ring having a pair of concave pockets  382  on its rear surface and a pair of correspondingly shaped convex cams  384  on its front surface. The concave pockets  382  are oriented at 90° with respect to the convex cams  384  so that adjacent discs may be stacked such that the cams of a disc fit within the pockets of the adjacent disc. The corresponding shaped cams  384  and pockets  382  help prevent the discs from rotating with respect to one another. Holes or lumens  386  are formed through the annular ring  380  for passage of a number of control cables  390   a ,  390   b ,  390   c ,  390   d , as shown in  FIG. 19B . The holes or lumens  386  may be positioned at the center of the cams and pockets. However, the holes for the control cables may be offset from the position of the cams and pockets, if desired. Preferably discs  380  are molded from a biocompatible polymer having a relatively slick surface, such as polyurethane, polypropylene, or polyethylene, that reduces friction between adjacent cams and pockets. 
       FIGS. 20A and 20B  show yet another alternative embodiment of an articulation joint. In this embodiment, the articulation joint is formed of a stack of discs, each of which comprises an annular ring. The annular ring has cams having an arcuate slot  392  molded therein that allows a control cable to move more freely in the cam as the disc is moved relative to an adjacent disc. As best shown in  FIG. 20B , the slot  392  tapers from a widest point  394  at the outer edge of the cam to a narrow point  396  where the slot forms a cylindrical hole  398  that extends to the opposite edge of the annular ring  380 . A control wire  390   b  is free to bend within the widened portion of the arcuate slot  392  as an adjacent disc is rotated. 
     Although the discs of the articulation joints shown in  FIGS. 18-20  are generally circular in shape, it will be appreciated that other shapes could be used.  FIGS. 21A and 21B  show an articulation joint formed from a number of sections having a generally square outer shape. As shown in  FIG. 21A , a section  400  is a square band having a pair of pins  402  that extend outwardly on opposite sides of the rear surface of the square section. On the opposite sides of the front surface are a pair of opposing circular recesses  404  that are sized to receive the round pins  402  of an adjacent section. The embodiment shown, the control cables are routed through holes or lumens in corner blocks  406  that are found in each corner of the square section  400 .  FIG. 21B  shows two adjacent square sections  400   a ,  400   b  secured together. As can be seen, the section  400   b  can rotate up or down on its pins with respect to the adjacent section  400   a . Although circular and square articulation sections have been shown, it will be appreciated that other segment shapes such as triangular or pentagonal, etc., could also be used to form an articulation joint. 
     In some environments, a full 180° turning radius of the distal tip of the imaging endoscope may not be necessary. In those environments, the articulation joint may be replaced with a flexible member such as a braided stent.  FIG. 22  shows an imaging endoscope  425  having a braided stent  430  as the articulation joint. The braided stent extends between a distal tip  432  and a connector  434  that joins the proximal end of the stent  430  with the distal end of a flexible shaft  436 . A cover  438  extends over the flexible shaft  436  and the braided stent  430 . Control cables (not shown) extend through a lumen of flexible shaft  436  and are used to pull the stent  430  such that the distal tip  432  is oriented in the desired direction. In addition, pulling all the control cables simultaneously allows the distal tip of the endoscope to be retracted. 
       FIG. 23  shows one method of securing the distal ends of the control cables to a braided stent  430 . The control cables  440   a ,  440   b ,  440   c ,  440   d  can be woven through the wires of the stent  430  and terminated by forming loops around the wires that comprise the stent. Alternatively, the ends of the cables  440  can be soldered or adhesively secured to the wires of the stent. 
     In some embodiments, the articulation joint is designed to exert a restoring force so that imaging endoscope will tend to straighten upon the release of tension from the control cables. In other cases, it may be desirable to maintain the position of the distal tip in a certain direction. In that case, a construction as shown in  FIG. 24  can be used. Here, the shaft of the imaging endoscope includes an inner sleeve  450  that is overlaid with two or more plastic spiral wraps  452 ,  454 , and  456 . Wrap  452  is wound in the clockwise direction while wrap  454  is wound in the counter-clockwise direction over the wrap  452  and the wrap  456  is wound in the same direction as the first wrap  452 . The wraps are formed of a relatively coarse plastic material such that friction is created between the alternatingly wound layers of the wrap. A suitable material for the plastic wrap includes a braided polyester or polyurethane ribbon. Upon tension of the imaging endoscope by any of the control cables, the plastic spiral wraps will move with respect to each other and the friction between the overlapping wraps will tend to maintain the orientation of the imaging endoscope in the desired direction. The endoscope will remain in the desired direction until it is pulled in a different direction by the control cables. Covering the alternatingly wound spiral wraps  452 ,  454 , and  456  is a braid  458 . The braid is formed of one or more plastic or wire threads wound in alternate directions. An outer sleeve  460  covers the braid  458  to complete the shaft. 
       FIG. 25  shows another alternative embodiment of a shaft construction used in an imaging endoscope according to the present invention. The shaft includes a cover sheath  470  having bands of a high durometer material  472  and a low durometer material  474  that alternate around the circumference of the sheath  470 . The high durometer material and low durometer materials form longitudinal strips that extend along the length of the shaft. Within the sheath  470  is a plastic spiral wrap  474  that prevents the shaft  470  from crushing as it is bent in a patient&#39;s anatomy. The high durometer materials add to the torque fidelity characteristics of the shaft. The width of the high durometer material strips compared to the low durometer material may be adjusted in accordance with the torque fidelity characteristics desired. 
     During examination with the imaging endoscope, the physician may need to twist the scope in order to guide it in the desired direction. Because the outer surface of the scope is preferably coated with a lubricant and it is round, it can be difficult for the physician to maintain an adequate purchase on the shaft in order to rotate it. As such, the imaging endoscope of the present invention may include a gripper mechanism that aids the physician in grasping the shaft for either rotating it or moving the shaft longitudinally. One embodiment of a shaft gripping device is shown in  FIG. 26 . Here, a gripper  500  comprises a u-shaped member having a pair of legs  502 ,  504  that are aligned with the longitudinal axis of an imaging endoscope  20 . At the distal end of the legs  502 ,  504  are two 90° bends  506 ,  508 . The gripper  500  includes a hole  505  positioned at the curved bent portion of the gripper that joins the legs as well as holes in each of the 90° sections  506 ,  508 . The imaging endoscope passes through the holes such that the gripper  500  is slideable along the length of the shaft portion of the endoscope. The spring nature of the material used to fashion the gripper causes the legs  502 ,  504  to be biased away from the shaft of the endoscope. Only the friction of the opposing holes at the bent portions  506 ,  508  prevent the gripper  500  from freely sliding along the length of the shaft. On the inner surface of the legs  502 ,  504  are a pair of touch pads  510 ,  512 , having an inner surface that is shaped to match the outer circumference of the shaft portion of the endoscope. When the physician squeezes the legs  502 ,  504  radially inward, the touch pads  510 ,  512  engage the shaft such that the physician can push or pull the endoscope or rotate it. Upon release of the legs  502 ,  504 , the touch pads  510 ,  512  release from the surface of the shaft and the gripper  500  can be moved along the length of the shaft to another location if desired. 
       FIG. 27  shows a gripper similar to that of  FIG. 26  with like parts being identified with the same reference numbers. In this embodiment, the gripper includes two hemispherical discs  520 ,  522 , positioned on the outside surface of the legs  502 ,  504 . The hemispherical surfaces  520 ,  522  are designed to fit within the hand of the physician and increase the radial distance from the gripper to the shaft such that it is easier to twist the shaft, if desired. 
       FIG. 28  shows yet another alternative embodiment of a shaft gripper. In this example, a gripper  550  comprises a u-shaped member having a pair of legs  552 ,  554 , that are oriented perpendicularly to the longitudinal axis of the imaging endoscope  20 . The legs  552 ,  554  include a recessed section  556 ,  558  that is shaped to receive the outer diameter of the shaft portion of the endoscope. A thumbscrew  560  is positioned at the distal end of the legs such that the legs can be drawn together and cause the legs  554 ,  556  to securely engage the shaft of the endoscope. Upon release of the thumbscrew  560 , the legs  554 ,  552  are biased away from the shaft such that the gripper  550  can be moved. The shaft can be twisted by rotating the legs  552 ,  554 , with respect to the longitudinal axis of the shaft. 
       FIG. 29  shows an alternative embodiment of the gripper  550  shown in  FIG. 28 . In this example, the gripper  580  includes a u-shaped member having a pair of legs  582 ,  584 . At the distal end of each leg is a recess  586 ,  588  that is shaped to receive the outer diameter of the shaft. The shaft is placed in the recesses  586 ,  588 , and a thumbscrew is positioned between the ends of the legs  582 ,  584 , and the u-shaped bend in the gripper  580 . By tightening the thumbscrew  590 , the legs are compressed against the shaft of the imaging endoscope  20 , thereby allowing the physician to rotate the endoscope by moving the gripper  580 . 
     In one embodiment of the invention the endoscope has a movable sleeve that operates to keep the distal end of the endoscope clean prior to use and covers the end of the scope that was in contact with a patient after the scope has been used. 
       FIGS. 30A and 30B  illustrate one embodiment of an endoscope  594  having a sponge  504  at its distal end. The sponge fits over the endoscope and has a peel off wrapper that may be removed and water or other liquid can be applied to the sponge. The water activates a hydrophilic coating so that the distal end of the endoscope has an increased lubricity. In addition, the sponge functions as a gripper when compressed allowing the physician to pull and/or twist the endoscope. 
     A collapsible sleeve  598  is positioned over the distal end of the endoscope and can be retracted to expose the lubricated distal tip of the probe. In one embodiment, the sleeve  598  is secured at its distal end to the sponge  594  and at its proximal end to the breakout box. Moving the sponge proximally retracts the sleeve so that the endoscope is ready for use. After a procedure, the sponge  594  is moved distally to extend the sleeve over the distal end of the endoscope. With the sleeve extended, any contaminants on the probe are less likely to contact the patient, the physician or staff performing the procedure. 
     In some instances, it may be desirable to limit the amount of heat that is dissipated at the distal end of the imaging endoscope. If light emitting diodes are used, they generate heat in the process of producing light for illumination. Similarly, the image sensor generates some heat during operation. In order to limit how hot the distal end of the endoscope may become and/or to provide for increased life for these components, it is necessary to dissipate the heat. One technique for doing so is to fashion a heat sink at the distal tip of the imaging endoscope. As shown in  FIG. 31 , a distal tip  600  includes a cap  602  and a heat dissipating section  604  that is made of a heat dissipating material such as a biocompatible metal. The heat dissipating section  604  includes a semicircular opening  606  having a relatively flat base  608  that extends approximately along the diameter of the heat dissipating section  604 . The flat base  608  forms a pad upon which electrical components such as the LEDs and image sensor can be mounted with a thermally conductive adhesive or other thermally conductive material. The heat generating devices will transfer heat generated during operation to the heat dissipating section  604 . The distal cover  602  covers the distal end of the heat dissipating section  604  in order to prevent the heat dissipating section  604  from touching the tissue in the body as well as to protect the body as the imaging catheter is moved in the patient. Prisms, lenses, or other light bending devices may be needed to bend light entering the distal end of the endoscope to any imaging electronics that are secured to the relatively flat base  608  of the heat dissipating section  604 . 
       FIG. 32  shows a heat dissipating distal tip of an endoscope wherein the distal tip does not include a cover but is molded from a single piece of heat dissipating material such as a biocompatible metal. The heat dissipating section  620  again includes a semicircular opening with a relatively flat surface  622  that extends along the diameter of the section and on which heat generating electronic devices can be mounted. With a semicircular opening formed in the distal end of the heat dissipating distal tip  620 , the illumination mechanism and image sensor are mounted on the flat surface  622 . The irrigation port is oriented to direct water over the hemispherical cutout in order to clean the illumination mechanism and image sensor or image sensor lenses. 
     In yet another embodiment of the invention, the imaging devices at the distal end of the endoscope can be cooled by air or water passed through a lumen to the end of the endoscope and vented outside the body. For example, air under pressure may be vented through an orifice near the imaging electronics. The expansion of the air lowers its temperature where it cools the imaging electronics. The warmed air is then forced to the proximal end of the endoscope through an exhaust lumen. Alternatively, the endoscope may include a water delivery lumen that delivers water to a heat exchanger at the distal tip. Water warmed by the electronic components in the distal tip is removed in a water return lumen. 
       FIG. 33  shows an alternative embodiment of the heat dissipating distal tip shown in  FIG. 31 . In this example, the heat dissipating distal tip  640  has a number of scalloped channels  642  positioned around the circumference of the distal tip. The scalloped channels  642  increase the surface area of the heat dissipating distal tip, thereby further increasing the ability of the tip to dissipate heat from the illumination and imaging electronic devices. 
     Although the present endoscopic imaging system has many uses, it is particularly suited for performing colonoscopic examinations. In one embodiment, a 10-13 mm diameter prototype having a 0.060 inner spiral wrap with a pitch of ¼ inch and coated with a hydrophilic coating was found to have a coefficient of friction of 0.15 compared to 0.85 for conventional endoscopes. In addition, the endoscope of the present invention required 0.5 lbs. of force to push it through a 2-inch U-shaped bend where a conventional endoscope could not pass through such a tight bend. Therefore, the present invention allows colonoscopes to be made inexpensively and lightweight so that they are more comfortable for the patient due to their lower coefficient of friction and better trackability. 
     In addition to performing colonoscopies, the endoscopic imaging system of the present invention is also useful with a variety of surgical devices including: cannulas, guidewires, sphincterotomes, stone retrieval balloons, retrieval baskets, dilatation balloons, stents, cytology brushes, ligation devices, electrohemostasis devices, sclerotherapy needles, snares and biopsy forceps. 
     Cannulas are used with the endoscopic imaging system to cannulate the sphincter of Odi or papilla to gain access to the bile or pancreatic ducts. Guidewires can be delivered down the working channel of the endoscope and used as a rail to deliver a surgical device to an area of interest. Sphincterotomes are used to open the papilla in order to place a stent or remove a stone from a patient. Stone retrieval balloons are used along with a guidewire to pull a stone out of a bile duct. Retrieval baskets are also used to remove stones from a bile duct. Dilatation balloons are used to open up strictures in the gastrointestinal, urinary or pulmonary tracts. Stents are used to open up strictures in the GI, urinary or pulmonary tracts. Stents can be metal or plastic, self-expanding or mechanically expanded, and are normally delivered from the distal end of a catheter. Cytology brushes are used at the end of guidewires to collect cell samples. Ligation devices are used to ligate varices in the esophagus. Band ligators employ elastic bands to cinch varices. Electrohemostasis devices use electrical current to cauterize bleeding tissue in the GI tract. Sclerotherapy needles are used to inject coagulating or sealing solutions into varices. Snares are used to remove polyps from the GI tract, and biopsy forceps are used to collect tissue samples. 
     Examples of specific surgical procedures that can be treated with the endoscopic imaging system of the present invention include the treatment of gastroesophageal reflux disease (GERD) by the implantation of bulking agents, implants, fundoplication, tissue scarring, suturing, or replacement of valves or other techniques to aid in closure of the lower esophageal sphincter (LES). 
     Another example of a surgical procedure is the treatment of morbid obesity by deploying implants or performing reduction surgery, gastric bypass and plication or creating tissue folds to help patients lose weight. 
     Endoscopic mucosal resection (EMR) involves the removal of sessile polyps or flat lesions by filling them with saline or the like to lift them prior to resection. The endoscope of the present invention can be used to deliver needles, snares and biopsy forceps useful in performing this procedure. 
     In addition, the endoscopic imaging system of the present invention can be used to perform full-thickness resection (FTRD) in which a portion of a GI tract wall is excised and the wounds healed with staplers or fasteners. Finally, the endoscopic imaging system of the present invention can be used to deliver sclerosing agents to kill tissues or drug delivery agents to treat maladies of internal body tissues. 
     While the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the scope of the invention. For example, although some of the disclosed embodiments use the pull wires to compress the length of the endoscope, it will be appreciated that other mechanisms such as dedicated wires could be used. Alternatively, a spring can be used to bias the endoscope distally and wires used to compress the spring thereby shortening the length of the endoscope. Therefore, the scope of the invention is to be determined from the following claims and equivalents thereof.