Patent Publication Number: US-2009231419-A1

Title: Endoscope Assembly and Method of Performing a Medical Procedure

Description:
This application claims the benefit of U.S. Provisional Patent Application No. 60/979,367, filed Oct. 11, 2007, the entire disclosure of which is incorporated herein by reference. 
     This application is a continuation-in-part application of U.S. patent application Ser. No. 11/672,020, filed Feb. 6, 2007, the entire disclosure of which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to an endoscope assembly and a method of performing a medical procedure. 
     BACKGROUND OF THE INVENTION 
     An endoscope is a medical device comprising a flexible tube and a camera mounted on the distal end of the tube. The endoscope is insertable into an internal body cavity through a body orifice or a surgical incision to examine the body cavity and tissues for diagnosis. The tube of the endoscope has one or more longitudinal channels, through which an instrument can reach the body cavity to take samples of suspicious tissues or to perform other surgical procedures such as polypectomy. 
     There are many types of endoscopes, and they are named in relation to the organs or areas with which they are used. For example, gastroscopes are used for examination and treatment of the esophagus, stomach and duodenum; colonoscopes for the colon; bronchoscopes for the bronchi; laparoscopes for the peritoneal cavity; sigmoidoscopes for the rectum and the sigmoid colon; arthroscopes for joints; cystoscopes for the urinary bladder; and angioscopes for the examination of blood vessels. 
     Many conventional endoscopes are characterized by a single forward viewing camera mounted at the distal end of the endoscope to transmit an image to an eyepiece or video display at the proximal end. The camera is used to assist a medical professional in advancing the endoscope into a body cavity and looking for abnormalities. The camera provides the medical professional with a two-dimensional view from the distal end of the endoscope. To capture an image from a different angle or in a different portion, the endoscope must be repositioned or moved back and forth. Repositioning and movement of the endoscope prolongs the procedure and causes added discomfort, complications, and risks to the patient. Additionally, in an environment such as the lower gastro-intestinal tract, flexures, tissue folds and unusual geometries of the organ may prevent the endoscope&#39;s camera from viewing the “hidden” areas of the organ and prevent the instrument from reaching the “hidden” areas (or at least make it difficult for the instrument to reach these same areas). The inability to view the “hidden” areas may cause a potentially malignant polyp to be missed, and the inability (or difficulty) to reach the “hidden” areas may require an expensive and intrusive procedure to remove the polyp (or at least prolong the procedure to use the endoscope to remove the polyp). Furthermore, it is difficult to optimally remove a potentially malignant polyp using a conventional endoscope. The difficulty to see and reach a polyp often results in only partial removal of the polyp or removal of normal tissues in addition to the polyp, which increases the risk of the procedure to the patient. For example, to remove only the polyp without normal tissues requires a proper placement of a snare around the polyp. With a conventional endoscope, this is difficult to accomplish if the polyp is in a “hidden” area, because the inability or difficulty to see how the snare is placed round the polyp. 
     SUMMARY OF THE INVENTION 
     This problem associated with prior art endoscopes is overcome by the present invention. In one preferred embodiment, the present invention provides (1) an instrument that can reach areas that are difficult or impossible to reach with an instrument extending through a channel in the main endoscope and (2) possibly a second, auxiliary camera that presents an image from a different point-of-view and enables viewing of areas not viewable by the endoscope&#39;s main camera. This arrangement of cameras may provide different views of an area, and this arrangement of instruments may allow the instruments to reach an area from different angles. In another preferred embodiment, the second camera and instrument may be integrated to allow, for example, easy handling and cooperation between the second camera and the instrument. 
     According to one aspect of the invention, an endoscope assembly includes an endoscope that includes a tubular body, a retrograde-viewing imaging device disposed at a distal end region of the tubular body, and a channel extending through the tubular body; and an instrument extending through the channel of the endoscope and exits from a distal opening of the channel. 
     According to one embodiment of the invention, the instrument includes a cable and a head disposed at a distal end of the cable. 
     According to another embodiment of the invention, the head includes one of a snare, an electrocautery or a biopsy forceps. 
     According to still another embodiment of the invention, the cable includes an electrical wire for providing electric power to the head. 
     According to yet another embodiment of the invention, a portion of the instrument that extends outside of the distal opening of the channel of the endoscope includes a bend. 
     According to still yet another embodiment of the invention, the instrument bends at an angle between 30°to 150°. 
     According to a further embodiment of the invention, the instrument bends at an angle between 45° to 135°. 
     According to a still further embodiment of the invention, the instrument bends at an angle between 45° to 90°. 
     According to a yet further embodiment of the invention, at least the portion of the instrument forming the bend is made from a flexible shape memory material. 
     According to a still yet further embodiment of the invention, at least a distal portion of the instrument is steerable. 
     According to another further embodiment of the invention, the instrument is moveable along the channel of the endoscope and rotatable relative to the channel of the endoscope. 
     According to still another further embodiment of the invention, the distal opening of the channel is on a side surface of the distal end region of the tubular body. 
     According to yet another further embodiment of the invention, the distal opening of the channel is on a distal end of the tubular body. 
     According to still yet another further embodiment of the invention, the channel of the tubular body and the instrument are integrated so that the instrument cannot be removed from the channel, but the instrument has limited movement in or out of the channel. 
     According to another embodiment of the invention, the opening of the channel is on a distal end region of the endoscope, and the instrument projects forwards beyond the endoscope. 
     According to still another embodiment of the invention, the endoscope is a minor endoscope. The endoscope assembly further includes a main endoscope that includes an insertion tube, a forward-viewing imaging device disposed at a distal end region of the insertion tube, and a channel extending through the insertion tube. The minor endoscope extends through the channel of the insertion tube and exits from a distal opening of the channel of the insertion tube. 
     According to yet another embodiment of the invention, the minor endoscope is moveable along the channel of the insertion tube and rotatable relative to the channel of the insertion tube. 
     According to still yet another further embodiment of the invention, the endoscope assembly further includes a control box connected to the instruments to provide a monopolar current to the instruments. 
     According to another aspect of the invention, an endoscope assembly includes an endoscope that includes a tubular body and a retrograde-viewing imaging device disposed at a distal end region of the tubular body; and an instrument fixed to the distal end region of the tubular body. 
     According to one embodiment of the invention, the instrument includes a cable and a head disposed at a distal end of the cable. 
     According to another embodiment of the invention, the head includes one of a snare, an electrocautery or a biopsy forceps. 
     According to still another embodiment of the invention, the cable includes an electrical wire for providing electric power to the head. 
     According to yet another embodiment of the invention, the instrument is perpendicular to the distal end region of the tubular body. 
     According to still yet another embodiment of the invention, at least the portion of the instrument is made from a flexible shape memory material. 
     According to a further embodiment of the invention, the endoscope is a minor endoscope. The endoscope assembly further includes a main endoscope that includes an insertion tube, a forward-viewing imaging device disposed at a distal end region of the insertion tube, and a channel extending through the insertion tube. The minor endoscope extends through the channel of the insertion tube and exits from a distal opening of the channel of the insertion tube. 
     According to a still further embodiment of the invention, the minor endoscope is moveable along the channel of the insertion tube and rotatable relative to the channel of the insertion tube. 
     According to a yet further embodiment of the invention, the endoscope assembly further includes a control box connected to the instruments to provide a monopolar current to the instruments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         FIG. 1  shows a perspective view of an endoscope system with a major endoscope and a minor endoscope according to one embodiment of the present invention. 
         FIG. 2  shows a perspective view of the minor endoscope shown in  FIG. 1 . 
         FIG. 3  shows a perspective view of the distal end of the endoscope system of  FIG. 1 . 
         FIG. 4  shows a perspective view of the endoscope system of  FIG. 1  with an instrument. 
         FIG. 5  shows a perspective view of the endoscope system of  FIG. 1  with another instrument. 
         FIG. 6  shows a perspective view of the endoscope system of  FIG. 1  with still another instrument. 
         FIG. 7  shows a perspective view of the endoscope system of  FIG. 1  with a further instrument. 
         FIG. 8  shows a perspective view of the endoscope system of  FIG. 1  with a still further instrument. 
         FIG. 9  shows a perspective view of a portion of a link belonging to the minor endoscope shown in  FIG. 2 . 
         FIG. 10  shows an exploded perspective view of the link belonging to the minor endoscope of  FIG. 2 . 
         FIG. 11  shows a perspective view of an endoscope system with a major endoscope and a minor endoscope according to another embodiment of the present invention. 
         FIG. 12  shows a perspective view of the endoscope system of  FIG. 11  with an instrument extending from an opening on a side of the minor endoscope. 
         FIG. 13  shows a perspective view of the endoscope system of  FIG. 11  with an instrument extending from an opening on an end of the minor endoscope. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
       FIG. 1  illustrates a first exemplary endoscope system  1  of the present invention. This endoscope system  1  can be used in a variety of medical procedures in which imaging of a body tissue, organ, cavity or lumen is required. The types of procedures include, for example, anoscopy, arthroscopy, bronchoscopy, colonoscopy, cystoscopy, EGD, laparoscopy, and sigmoidoscopy. 
     The endoscope system  1  of  FIG. 1  includes a main endoscope  10  and a minor endoscope  20 . The main endoscope  10  includes an insertion tube  12 , a main imaging device  14  disposed at the distal end  16  of the insertion tube  12  ( FIG. 3 ), and a control handle  18  connected to the proximal end of the insertion tube  12 . The minor endoscope  20  is disposed at the distal and proximal ends of the insertion tube  12  and inside the insertion tube  12 . 
     In the main endoscope  10 , the insertion tube  12  may be detachable from the control handle  18  or may be integrally formed with the control handle  18 . The diameter, length and flexibility of the insertion tube  12  depend on the procedure for which the endoscope system  1  is used. 
     In the illustrated embodiment, as shown in  FIG. 3 , the main endoscope&#39;s insertion tube  12  has one longitudinal channel  22  for accommodating the minor endoscope  20 . In general, however, the insertion tube  12  may have one or more additional longitudinal channels through which an instrument, in addition to the minor endoscope  20 , can reach the body cavity to perform any desired procedures, such as to take samples of suspicious tissues or to perform other surgical procedures such as polypectomy. The instruments may be, for example, a retractable needle for drug injection, hydraulically actuated scissors, clamps, grasping tools, electrocoagulation systems, ultrasound transducers, electrical sensors, heating elements, laser mechanisms and other ablation means. In some embodiments, one of the channels can be used to supply a washing liquid such as water for washing. A cap (not shown) may be included at the opening of the washing channel to divert the washing liquid onto a lens of the main imaging device  14  for cleaning. Another or the same channel may be used to supply a gas, such as CO 2  or air, into the organ. The channels may also be used to extract fluids or inject fluids, such as a drug in a liquid carrier, into the body. Various biopsy, drug delivery, and other diagnostic and therapeutic devices may also be inserted via the channels to perform specific functions. 
     The insertion tube  12  preferably is steerable or has a steerable distal end region  24  as shown in  FIG. 1 . The length of the distal end region  24  may be any suitable fraction of the length of the insertion tube  12 , such as one half, one third, one fourth, one sixth, one tenth, or one twentieth. The insertion tube  12  may have control cables (not shown) for the manipulation of the insertion tube  12 . Preferably, the control cables are symmetrically positioned within the insertion tube  12  and extend along the length of the insertion tube  12 . The control cables may be anchored at or near the distal end  16  of the insertion tube  12 . Each of the control cables may be a Bowden cable, which includes a wire contained in a flexible overlying hollow tube. The wires of the Bowden cables are attached to controls  26  in the handle  18 . Using the controls, the wires can be pulled to bend the distal end region  24  of the insertion tube  12  in a given direction. The Bowden cables can be used to articulate the distal end region  24  of the insertion tube  12  in different directions. 
     The main imaging device  14  at the distal end  16  of the insertion tube  12  may include, for example, a lens, single chip sensor, multiple chip sensor or fiber optic implemented devices. The main imaging device  14 , in electrical communication with a processor and/or monitor, may provide still images or recorded or live video images. In addition to the main imaging device  14 , the distal end  16  of the insertion tube  12  may include one or more light sources  28  ( FIG. 3 ), such as light emitting diodes (LEDs) or fiber optical delivery of light from an external light source. The light sources  28  preferably are equidistant from the main imaging device  14  to provide even illumination. The intensity of each light source  28  can be adjusted to achieve optimum imaging. The circuits for the main imaging device  14  and light sources  28  may be incorporated into a printed circuit board (PCB). 
     The insertion tube  12  may include a flexible ribbon coil (not shown) and a flexible sheath (not shown) that is used to protect the internal components of the insertion tube  12 , such as the channels, wires and cables, from the environment of the body. 
     Preferably, the control handle  18  has one or more ports and/or valves (not shown) for controlling access to the channels of the insertion tube  12 . The ports and/or valves can be air or water valves, suction valves, instrumentation ports, and suction/instrumentation ports. As shown in  FIG. 1 , the control handle  18  may additionally include a buttons  30  for taking pictures with the main imaging device  14 , the minor endoscope  20 , or both. 
     The proximal end  32  of the control handle  18  may include an accessory outlet  34  ( FIG. 1 ) that provides fluid communication between the air, water and suction channels and the pumps and related accessories. The same outlet or a different outlet can be used for electrical lines to light and imaging components at the distal end of the endoscope system  1 . 
     As shown in  FIG. 2 , the minor endoscope  20  may include a tubular body  36 , a handle  38  connected to the proximal end  40  of the tubular body  36 , an auxiliary imaging device  42 , a link  44  that provides physical and/or electrical connection between the auxiliary imaging device  42  to the distal end  46  of the tubular body  36 , and a light source  45  (illustrated in  FIG. 3 ). 
     The minor endoscope  20  is used to provide an auxiliary imaging device at the distal end of the endoscope system  1 . To this end, the minor endoscope  20  is placed inside the channel  22  of the main endoscope&#39;s insertion tube  12  with its auxiliary imaging device  42  disposed beyond the distal end  16  of the main endoscope  10 . This can be accomplished by first inserting the distal end of the minor endoscope  20  into the main endoscope&#39;s channel  22  from the main endoscope&#39;s handle  18  and then pushing the minor endoscope  20  further into the channel  22  until the auxiliary imaging device  42  and link  44  of the minor endoscope  20  are positioned outside the distal end  16  of the main endoscope  10  as shown in  FIG. 3 . 
     The tubular body  36  of the minor endoscope  20  may have any suitable configuration. In terms of its length, the tubular body  36  preferably is sufficiently long such that the auxiliary imaging device  42  and link  44  can extend beyond the distal end  16  of the main endoscope  10 . The preferred cross-section of the illustrated tubular body  36  is circular, although the cross-section may have any other suitable configuration, such as an elliptical or polygonal configuration. 
     In the illustrated embodiment, as shown in  FIG. 3 , the tubular body  36  of the minor endoscope  20  has a channel  48  expanding the entire length of the tubular body  36 . This channel  48  may be used to accommodate an instrument  41 , such as snares, electrocautery or biopsy forceps. The instrument  41  extends from the proximal end of the minor endoscope  20  to the distal end and exits at the distal end of the channel  48 .  FIGS. 4-7  illustrate four examples  41   a,    41   b,    41   c,    41   d  of such an instrument  41 . 
     The instrument  41  can be used to reach areas that are difficult or impossible to reach with an instrument extending through a channel in the main endoscope  10 . The two instruments can reach an area from different angles. As shown in  FIGS. 4-7 , the instrument  41  may include a cable  43  ( 43   a,    43   b,    43   c,    43   d ) and a head  47  ( 47   a,    47   b,    47   c,    47   d ) attached to the distal end of the cable  43 . The instrument  41  may include also a handle (not shown). In some embodiments, the cable  43  may be a wire or a plurality of wires that are braided together. The cable  43  or a portion thereof may be made from a conducting metal such as steel or copper and may be used to conduct electricity to the head  47  of the instrument  41  to burn polyps. A sheath  49  can be included which wraps around the cable  43   d  as shown in  FIG. 7  to protect the electrical wires running through the cable  43   d.    
     In some preferred embodiments, the distal portion of the cable  43  may be pre-shaped to a number of forms as shown in  FIGS. 4 ,  5 ,  6  and  7 . For example, the cables  43   a,    43   c,    43   d  shown in  FIGS. 4 ,  6  and  7  bend at a 90° angle. In  FIG. 5 , the cable  43   b  bends at about a 130° angle. In general, the cable  43  may bend at any angle such as 15°, 30°, 45°, 60°, 75°, 105°, 120°, 135°, 150°, 165°, or 180°, or any angle within the range between any two of these angle values. As used herein, the “angle” means that the angle between the two portions of the cable that form the bend. For example, the cable  43   b  in  FIG. 5  bends at about a 130° angle, not at about a 50° angle. In some embodiments, the cable  43  may be made at least partially made from a flexible shape memory material that tends to return substantially to its original shape after deformation. Such a cable  43  may be straightened to allow the distal end of the instrument  41  to be inserted into the proximal end of the minor endoscope&#39;s channel  48  and then pushed towards the distal end of the minor endoscope  20 . When the distal end of the instrument  41  is pushed sufficiently out of the distal end of the minor endoscope&#39;s channel  48 , the distal end of the instrument  41  resumes its natural bent configuration as shown in  FIG. 4 ,  5 ,  6 , or  7 . 
     Alternatively, the instrument  41  or its distal end may be steerable. The instrument  41  may have control cables (not shown) for the manipulation of the instrument  41 . Preferably, the control cables are symmetrically positioned within the instrument  41  and extend along the length of the instrument  41 . The control cables may be anchored at or near the distal end of the instrument  41 . Each of the control cables may be a Bowden cable, which includes a wire contained in a flexible overlying hollow tube. The wires of the Bowden cables are attached to controls on the handle of the instrument  41 . Using the controls, an operator can pull the wires to bend the instrument  41  in a given direction. 
     The instrument  41  is free to move in the minor endoscope&#39;s channel  48 , and this movement can be effected by pulling, pushing or rotating the handle of the instrument  41 . This allows the instrument  41  to be independently manipulated with respect to the minor endoscope  20 . The minor endoscope&#39;s channel  48  may be coated with a protective coating such as Teflon to avoid damages to the instrument  41 . Furthermore, the minor endoscope&#39;s channel  48  may be reinforced with a lubricious liner such as PTFE or polyimide tubing to provide a lubricious surface to facilitate the movement of the instrument  41 . This channel  48  may also be used to control the flow of air into the body cavity (suction or insufflation) as well as to pass fluids such as water into the body cavity. 
     In order to create a sufficient space for the channel  48 , the electrical wires running through the wall can be coiled along the length of the instrument  41 . Instead of following a path that is parallel to the length of the instrument  41 , the electric wires can spiral around the channel in the wall of the instrument  41 , allowing more electric wires to be included in the wall of the instrument  41 . 
     The head  47  of the instrument  41  may be of any one of various devices. For example, the head  47   a,    47   b,    47   d  can be a probe such as an electrocautery. The head  47   c  can also be shaped like a snare to facilitate the grasping of peduncled lesions or polyps as shown in  FIG. 6 . The cable  43   c  of the instrument  41   c  may be hollow, allowing the snare  47   c  to extend therethrough. An operator may tighten the snare  41  c by pulling it from the proximal end of the instrument  41   c . The head  41  may further be biopsy forceps. The head  41  may also include a connector (not shown) to mate with a separate electrocautery generator. 
     The maneuvering of the head  47  to reach the desired location can be accomplished by manipulating the instrument  41  relative to the minor endoscope  20  and/or by manipulating the minor endoscope  20  relative to the main endoscope  10 . 
     As shown in  FIG. 8 , an instrument  51  may also be fixed to the minor endoscope  20  rather than being separate from the minor endoscope  20 , as shown in  FIG. 4-7 . In the embodiment shown in  FIG. 8 , the instrument  51  includes a head  53  and a short cable  55  connecting the head  53  to the link  44  of the minor endoscope  20 , although the head  53  can be connected to any part of the minor endoscope  20 . The head  53  may be the same or similar to any of the heads  47   a,    47   b,    47   c,    47   d  shown in  FIG. 4-7 . The head  53  shown in  FIG. 8  may be brought into contact with a desired area by manipulating the minor endoscope  20  relative to the main endoscope  10 . This creates a system without multiple components that have to be controlled. The fixed instrument  51  can be pre-shaped with the aid of a shape-memory material such as nitinol. This allows the instrument  51  to be flattened when the minor endoscope  20  slides through the channel  22  of the main endoscope  10 . In addition, a bridge  57  may be provided to connect the tubular body  36  of the minor endoscope  20  to the instrument  51  in order to conduct electricity to the instrument  51 . 
     The handle  38  of the minor endoscope  20  may control various functions of the minor endoscope  20 . For example, the handle  38  may serve as a convenient way to deploy and/or rotate the minor endoscope  20  inside the channel  22  of the main endoscope  10 . The handle  38  may also provide an access port  50  for the channel  48  of the tubular body  36 . The handle  38  may additionally provide a connector  52 , to which electrical conductors from the auxiliary imaging device  42  and other components of the minor endoscope  20  are connected. The connector  52  can be used to connect the auxiliary imaging device  42  and other components to a device outside of the minor endoscope  20 , such as a control box. The handle  38  may further provide a switch  54  that is used to operate the auxiliary imaging device  42  to capture still images. 
     As shown in  FIG. 9 , the auxiliary imaging device  42  may include a housing  56   a,    56   b  and an imaging unit  58  disposed in the housing  56   a,    56   b.  In this embodiment, the housing  56   a,    56   b  has a generally cylindrical configuration, but in general the housing may have any suitable configuration such as a spherical or cubic configuration. The housing  56   a,    56   b  includes two parts  56   a,    56   b  that are sealingly joined to form the housing  56   a,    56   b.  The housing  56   a,    56   b  may be made from any suitable material such as stainless steel or a plastic material. 
     As shown in  FIG. 9 , the imaging unit  58  may include a lens  62 , an imaging sensor  60 , and a printed circuit board (PCB)  64  containing electrical components of the imaging unit  58 . The lens  62  is installed in an aperture on a first end  66  of the housing  56   a,    56   b,  and may include a plurality of optical elements in a holder or barrel which focuses the incoming light from the surroundings onto a photosensitive area of the image sensor  60 . 
     The imaging sensor  60  may be an electronic device which converts light incident on photosensitive semiconductor elements into electrical signals. The imaging sensor  60  may detect either color or black-and-white images. The signals from the imaging sensor  60  can be digitized and used to reproduce an image that is incident on the imaging sensor  60 . Two commonly used types of image sensors are Charge Coupled Devices (CCD) such as a VCC-5774 produced by Sanyo of Osaka, Japan and Complementary Metal Oxide Semiconductor (CMOS) camera chips such as an OVT 6910 produced by OmniVision of Sunnyvale, Calif. 
     Alternatively, the imaging unit  58  may include a coherent fiber optic bundle and a lens for channeling light into the coherent fiber optic bundle, which then delivers the light from the distal end of the minor endoscope  20  to an imaging sensor located at the proximal end of, or external to, the imaging catheter. 
     On its second end  68 , the housing  56   a,    56   b  of the auxiliary imaging device  42  may include an opening  70  ( FIG. 3 ) for a flexible PCB  76  ( FIG. 9 ) to pass through for connection with the imaging unit  58 . The flexible PCB  76  electrically connects the imaging unit  58  to the electrical conductors  78  ( FIG. 10 ) which extend through tubular body  36 . 
     When the minor endoscope  20  is properly installed in the insertion tube  12 , the auxiliary imaging device  42  of the minor endoscope  20  preferably faces backwards towards the main imaging device  14  as illustrated in  FIG. 3 . The auxiliary imaging device  42  may be oriented so that the auxiliary imaging device  42  and the main imaging device  14  have adjacent or overlapping viewing areas. Alternatively, the auxiliary imaging device  42  may be oriented so that the auxiliary imaging device  42  and the main imaging device  14  simultaneously provide different views of the same area. Preferably, the auxiliary imaging device  42  provides a retrograde view of the area, while the main imaging device  14  provides a front view of the area. 
     As shown in  FIGS. 2 and 3 , the link  44  connects the auxiliary imaging device  42  to the distal end  46  of the tubular body  36 . Preferably, the link  44  is a flexible link that is at least partially made from a flexible shape memory material that tends to return substantially to its original shape after deformation. Shape memory materials are well known and include shape memory alloys and shape memory polymers. A suitable flexible shape memory material is a shape memory alloy such as nitinol. The flexible link  44  is straightened to allow the distal end of the minor endoscope  20  to be inserted into the proximal end of channel  22  of the insertion tube  12  and then pushed towards the distal end  16  of the insertion tube  12 . When the flexible link  44  is straightened inside the channel  22  of the insertion tube  12 , the first end  66  of the auxiliary imaging device  42  faces away from the tubular body  36 , a direction parallel to the main imaging device  14 , while the second end  68  of the auxiliary imaging device  42  faces back towards the tubular body  36  and handle  38 . When the auxiliary imaging device  42  and flexible link  44  are pushed sufficiently out of the distal end  16  of the insertion tube  12 , the flexible link  44  resumes its natural bent configuration as shown in  FIG. 3 . The natural configuration of the flexible link  44  is the configuration of the flexible link  44  when the flexible link  44  is not subject to any force or stress. When the flexible link  44  resumes its natural bent configuration, the first end  66  of the auxiliary imaging device  42  faces substantially back towards the tubular body  36  ( FIG. 2 ) and back towards the distal end  16  of the insertion tube  12  ( FIG. 3 ) while the second end  68  of the auxiliary imaging device  42  faces away from the tubular body  36  ( FIG. 2 ) and away from the distal end  16  of the insertion tube  12  ( FIG. 3 ). 
     The flexible link may have any suitable configuration that allows it to be straightened under force and to return to its natural bent configuration when the force is removed. For example, the flexible link may have a U-shaped, S-shaped, right angle, or ramp configuration. In the illustrated embodiment, the flexible link  44  has a U-shaped natural configuration with two end segments that are substantially parallel to each other. Preferably, the distance between the end segments is equal to or less than a diameter of the insertion tube. One of the end segments is connected to the auxiliary imaging device  42  and other end segment is connected to the tubular body  36 . Although the end segment connected to the tubular body  36  is much longer in the illustrated embodiment, the end segment connected to the auxiliary imaging device  42  may be longer in other embodiments. The flexible link  44  may have a generally elongated flat configuration with a hollow tubular end  72  for connection to the tubular body  36 . As shown in  FIG. 9 , the hollow tubular end  72  of the flexible link  44  may be attached to the distal end  46  of the tubular body  36  by concentrically mating with the channel  48  of the tubular body  36 . The attachment may be accomplished by any suitable means including adhesive bonding, welding or soldering. At the other end, the flexible link  44  may be joined to the auxiliary imaging device  42  by any suitable means such as adhesive bonding, welding or soldering. 
     In the illustrated embodiment, as shown in  FIGS. 9 and 10 , the flexible link  44  may include a flexible shape memory element  74  and a flexible PCB  76  that electrically connects the auxiliary imaging device  42  to the electrical conductors  78  in the tubular body  36 . The flexible shape memory element  74  preferably performs the shape memory function of the flexible link  44 , and the flexible PCB  76  is attached to the flexible shape memory element  74  so that its shape changes with the shape of the flexible shape memory element  74 . Alternatively, the flexible PCB  76  and flexible shape memory element  74  may be merely placed next to one another but not attached. Even when the flexible PCB  76  and flexible shape memory element  74  are not attached to each other, they will still undergo substantially the same shape changes as long as they are appropriately configured (such as if their lengths are similar). In the illustrated embodiment, the flexible shape memory element  74  and flexible PCB  76  have a similar configuration and are stacked in the thickness direction of the flexible PCB  76  to form a layered structure. In general, however, they may have different configurations and may be arranged relative to each other in any other suitable manner. 
     As shown in  FIG. 9 , the flexible PCB  76  includes electrical conductors  80  that connect the auxiliary imaging device  42  to the electrical conductors  78  in the tubular body  36 . At one end  82  of the flexible PCB  76 , the electrical conductors  80  of the flexible PCB  76  are connected to the auxiliary imaging device  42 . At the other end  84  of the flexible PCB  76 , the electrical conductors  80  of the flexible PCB  76  are connected to the electrical conductors  78  in the tubular body  36 . This end  84  of the flexible PCB  76  may have pads  86  for the connection between the electrical conductors  78  and electrical conductors  80 . 
     In the illustrated embodiment, the light source  45  (as well as other components) of the minor endoscope  20  is placed on the flexible link  44 , in particular on the curved concave portion of the flexible link  44 , although the light source  45  may be placed at any other suitable position, such as on the rear facing end of the auxiliary imaging device  42 . 
     The flexible link may be encapsulated or shrouded by flexible tubing, heat-shrinkable tubing, urethanes, rubber or silicon so as to allow smooth profile transition from the tubular body to the imaging device. This encapsulation may be translucent to allow light from the light source to project through the encapsulation, or the encapsulation may include a window section around each light source. 
     Since the main imaging device  14  and its light source  28  face the auxiliary imaging device  42  and its light source  45 , the light sources  28 ,  45  of the imaging devices  14 ,  42  may interfere with the opposing imaging device  42 ,  14 . That is, light source  28  may shine directly into auxiliary imaging device  42  and light source  45  may shine directly into main imaging device  14 , degrading both images. To reduce the interference, polarizer filters may be used with the imaging devices  14 ,  42  and light sources  28 ,  45 . Specifically, the main imaging device  14  and/or its light source  28  may be covered by a first set of polarizer filters of a given orientation. And the auxiliary imaging device  42  and/or its light source  45  may be covered by a second set of polarizer filters orientated at 90° relative to the first set of polarizer filters. The use of polarizer filters to reduce light interference is well known and will not be described in further detail. 
     As an alternative to polarizer filters, the imaging devices  14 ,  42  and their light sources  28 ,  45  may be turned on and off alternately to reduce or prevent light interference. In other words, when the main imaging device  14  and its light sources  28  are turned on, the auxiliary imaging device  42  and its light source  45  are turned off. And when the main imaging device  14  and its light sources  28  are turned off, the auxiliary imaging device  42  and its light source  45  are turned on. Preferably, the imaging devices  14 ,  42  and their light sources  28 ,  45  are turned on and off at a sufficiently high frequency that eyes do not sense that the light sources are being turned on and off. 
     The auxiliary imaging device  42  and its light source  45  are connected to a control box (not shown) via electrical conductors that extend from the imaging device  42  and light source  45 ; through the flexible PCB  76 , tubular body  36 , and handle  38 ; to the control box. The electrical conductors may carry power and control commands to the auxiliary imaging device  42  and its light source  45  and image signals from the auxiliary imaging device  42  to the control box. In the illustrated embodiment, the electrical conductors  78  in the tubular body  36  may be embedded in the wall of the tubular body  36 , or simply in the tubular body if the tubular body does not have a channel, during the fabrication process or disposed in the channel  48  of the tubular body  36 . The embedding of the electrical conductors in the tubular body  36  may be done by a braiding or coiling process to achieve the desired stiffness of the tubular body  36 . A short length of the embedded electrical conductors may be exposed at either end of the tubular body  36  to allow connections to be made. The connections may then be sealed by means of, for example, heat-shrinking tubing, a sheath or an adhesive. 
     The control box includes at least an image and signal processing device and a housing in which the image and signal processing device is disposed, although the control box can be configured in any suitable manner. The housing may include a control panel and connectors. 
     The control panel includes buttons and knobs for controlling the functionalities of the control box. 
     The image and signal processing device may include one or more integrated circuits and memory devices along with associated discrete components. The device allows image signals from the imaging devices  14 ,  42  to be processed for the enhancement of image quality, extraction of still images from the image signals, and conversion of video format for compatibility with the display device. 
     The control box preferably processes the video image signal from the auxiliary imaging device  42  and transmits it to a display device such as a television or a monitor such as a liquid crystal display monitor. Still images can be captured from the video image signal using the switch  54  on the handle  38  of the minor endoscope  20 . The video image or still image may be displayed on the display device. The display device may also include textual data that are used to display information such as patient information, reference numbers, date, and/or time. 
     The image signal from the main imaging device  14  may also be processed by the control box in the same way that the image signal from the auxiliary imaging device  42  is processed. The images from the main and auxiliary imaging devices  14 ,  42  may be displayed on two separate monitors or on the same monitor with a split screen. 
     The control box may further be used to adjust the parameters of the imaging devices  14 ,  42  and their light sources  28 ,  45 , such as brightness, exposure time and mode settings. The adjustment can be done by writing digital commands to specific registers controlling the parameters. The registers can be addressed by their unique addresses, and digital commands can be read from and written to the registers to change the various parameters. The control box can change the register values by transmitting data commands to the registers. 
     The control box may additionally be used as an interface to the patient records database. A large number of medical facilities now make use of electronic medical records. During the procedure relevant video and image data may need to be recorded in the patient electronic medical records (EMR) file. The signal processing circuit can convert image and video data to a format suitable for filing in the patient EMR file such as images in .jpeg, tif, or .bmp format among others. The processed signal can be transmitted to the medical professional&#39;s computer or the medical facilities server via a cable or dedicated wireless link. A switch on the control panel can be used to enable this transmission. Alternatively the data can be stored with a unique identification for the patient in electronic memory provided in the control box itself. The signal processing circuit can be utilized to convert the video and image data to be compatible with the electronic medical records system used by the medical professional. The processing may include compression of the data. A cable or a wireless link may be used to transmit the data to a computer. 
     The instruments  41 ,  51  shown in  FIGS. 4-8  may be directly attached to the control box, which may include electronic circuits to administer a monopolar current to the instruments  41 ,  51 . In such an embodiment, the control box preferably includes a connector for the instruments  41 ,  51  to transmit the monopolar current to the instruments  41 ,  51 . In addition, the control box may include connections to a return electrode, which includes a pad that is attached to the patient. The control box in this embodiment may also include a knob which allows the operator to vary the wattage provided by the monopolar current. In a further embodiment, the control box may send a bipolar current through the instruments  41 ,  51 , and a separate return electrode would not be needed. The return electrode may be integrated into the heads of the instruments  41 ,  51 . 
       FIG. 11  illustrates a further embodiment of the present invention. In this embodiment, an endoscope system  101  includes a main endoscope  110  having an insertion tube  112 , and an minor endoscope  120  positioned at the distal end of and inside the main endoscope  110 . The minor endoscope  120  includes an auxiliary imaging device  142  disposed at the distal end of the minor endoscope  120 . The auxiliary imaging device  142  includes an imaging unit  158  and a light source  145 . When the minor endoscope  120  is properly installed in the main endoscope  110 , the auxiliary imaging device  142  of the minor endoscope  20  preferably faces backwards towards the main imaging device (not shown). The auxiliary imaging device  142  may be oriented so that the auxiliary imaging device  142  and the main imaging device have adjacent or overlapping viewing areas. Alternatively, the auxiliary imaging device  142  may be oriented so that the auxiliary imaging device  142  and the main imaging device simultaneously provide different views of the same area. Preferably, the auxiliary imaging device  142  provides a retrograde view of the area, while the main imaging device provides a front view of the area. However, the auxiliary imaging device  142  could be oriented in other directions to provide other views, including views that are substantially parallel to the axis of the main imaging device. 
     The distal end region of the minor endoscope  120  preferably is made by shape setting of the minor endoscope  120  itself. This process is widely used and understood in the art and involves a process combination of heat and fixturing to create the pre-shaped distal end. The pre-shaped distal end may be supported by a piece of a shape memory material such as nitinol set in a similar shape. In general, this endoscope system  101  may be similar to the endoscope system  1  shown in  FIGS. 1-10 , except the distal end portion of the minor endoscope  120 . 
     As shown in  FIG. 12 , the minor endoscope  120  shown in  FIG. 11  may include an instrument  141 , such as snares, electrocautery or biopsy forceps. The instrument  141  may be integrated directly into a channel  148  of the minor endoscope  120 . The channel  148  has an opening  150  on the minor endoscope&#39;s distal end region that is outside of the distal end of the main endoscope  110 . Preferably, the instrument  141  can still be manipulated to move in or out of the channel  148  of the minor endoscope  120  by manipulating a handle of the instrument  141  on the proximal end. But the instrument  141  may not be removed from the channel  148  of the minor endoscope  120  and replaced with a different instrument. Such an arrangement may minimize the space requirements of the instrument  141 , allowing for additional space in the channel  148  of the minor endoscope  120  for additional electrical wires and/or insulation. 
       FIG. 13  illustrates a variation to the embodiment shown in  FIG. 12 . In this embodiment, the instrument  141  extends outside of the minor endoscope  120  through an opening  152  on a distal end region of the minor endoscope  120  and projects forwards beyond the minor endoscope  120 . In this embodiment, the operator may withdraw the minor endoscope  120  back toward the distal tip of the main endoscope  110 , so that the instrument  141  that projects beyond the minor endoscope  120  is closer to the distal tip of the main endoscope  110 , making it easier to manipulate and control instrument  141 . In this embodiment, it may be made possible to remove the instrument  141  from the channel  154  of the minor endoscope  120  so that the channel  154  may serve as an accessory channel for other accessory devices. The instrument  141  can be manipulated to move proximally or distally with respect to the minor endoscope  120  by manipulating a handle of the instrument  141  on the proximal end. 
     In an additional embodiment of the present invention, the auxiliary imaging device includes a wireless transceiver, associated circuitry and a battery. The wireless transceiver is configured to receive video signals from the imaging unit of the auxiliary imaging device and to transmit them wirelessly to a control box. Alternatively, the wireless circuit may be implemented in a flexible PCB or the handle of the minor endoscope. The control box may also include a wireless transceiver. This wireless transceiver enables the control box to receive wireless video signals from the imaging device and transmit control commands to the imaging device. 
     The wireless signal transmission and the use of batteries eliminate the need for electrical conductors within the tubular body  36 . This reduces the restrictions imposed by electrical conductors to the physician&#39;s movements of the endoscope. Additionally, reducing the number of electrical conductors in the catheter and the flex-PCB allows for a larger diameter channel to be included in the catheter. 
     During endoscopy, a physician may first insert the main endoscope  10  into a body cavity. She may then straighten the flexible link  44  of the minor endoscope  20  and then insert the straightened distal end of the minor endoscope  20  into the channel  22  of the main endoscope&#39;s insertion tube  12  from the handle  18 . The minor endoscope  20  can then be pushed towards the distal end  16  of the main endoscope  10 . When the auxiliary imaging device  42  and flexible link  44  are pushed out of the distal end  16  of the main endoscope  10 , the flexible link  44  resumes its natural bent configuration as shown in  FIG. 2 . If the minor endoscope  20  does not have an instrument fixed thereon as shown in  FIGS. 8 and 12 , the physician may then straighten an instrument  41  then insert the straightened instrument  41  into the channel  48  of the minor endoscope  20 . The instrument  41  can then be pushed towards the distal end of the minor endoscope  20 . When the instrument  41  is pushed out of the distal end of the channel  48 , the distal end of the instrument  41  resumes its natural bent configuration as shown in  FIGS. 4-7 . The physician may also insert a second instrument into a second channel of the main endoscope  10 . 
     The physician may use the two imaging devices  14 ,  42  to examine the body cavity, and then use the instrument  41  (or another instrument in the main endoscope  10 ) and one or both of the imaging devices  14 ,  42  to perform a desired procedure. For example, the instrument  41  (or the instrument in the main endoscope  10 ) may be a snare, and the physician may use the snare to remove a polyp. The physician may first maneuver the snare to place it around the polyp with the assistance of one or both of the imaging devices  14 ,  42 . Viewing the images provided by the imaging devices  14 ,  42 , the physician can ensure that the snare is properly placed around the polyp. Then she can tighten the snare to remove the polyp. 
     While the imaging catheter has been described throughout the description as being deployed inside an endoscope, in other applications it may be deployed through other methods such as through a straight tube or cannula, by a flexible insertion tube, or by a guide wire.