Abstract:
A system for advancing an instrument along an arbitrary path includes a flexible and steerable instrument and an electronic memory configured to store a three-dimensional model of the path, the three-dimension model being generated based on signals from the instrument as it traverses along the path. The system further includes an electronic motion controller logically coupled to the electronic memory, wherein the electronic motion controller is configured to automatically control the instrument to traverse the path based on the three dimensional model.

Description:
CROSS-REFERENCE TO OTHER APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 14/148,322, filed Jan. 6, 2014 (currently pending), which is a continuation of U.S. application Ser. No. 13/535,979, filed Jun. 28, 2012 (now U.S. Pat. No. 8,641,602), which is a continuation of U.S. application Ser. No. 11/129,093, filed May 13, 2005 (now U.S. Pat. No. 8,226,546), which is a continuation of U.S. application Ser. No. 10/229,189, filed Aug. 26, 2002 (now U.S. Pat. No. 7,044,907), which is a continuation of U.S. application Ser. No. 09/790,204, filed Feb. 20, 2001 (now U.S. Pat. No. 6,468,203), which claims priority to U.S. Provisional Application No. 60/194,140, filed Apr. 3, 2000, each of which is incorporated by reference herein in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to endoscopes and endoscopic medical procedures. More particularly, it relates to a method and apparatus to facilitate insertion of a flexible endoscope along a tortuous path, such as for colonoscopic examination and treatment. 
       BACKGROUND OF THE INVENTION 
       [0003]    An endoscope is a medical instrument for visualizing the interior of a patient&#39;s body. Endoscopes can be used for a variety of different diagnostic and interventional procedures, including colonoscopy, bronchoscopy, thoracoscopy, laparoscopy and video endoscopy. 
         [0004]    Colonoscopy is a medical procedure in which a flexible endoscope, or colonoscope, is inserted into a patient&#39;s colon for diagnostic examination and/or surgical treatment of the colon. A standard colonoscope is typically 135-185 mm in length and 12-13 mm in diameter, and includes a fiberoptic imaging bundle, illumination fibers and one or two instrument channels that may also be used for insufflation or irrigation. The colonoscope is inserted via the patient&#39;s anus and is advanced through the colon, allowing direct visual examination of the colon, the ileocecal valve and portions of the terminal ileum. Insertion of the colonoscope is complicated by the fact that the colon represents a tortuous and convoluted path. Considerable manipulation of the colonoscope is often necessary to advance the colonoscope through the colon, making the procedure more difficult and time consuming and adding to the potential for complications, such as intestinal perforation. Steerable colonoscopes have been devised to facilitate selection of the correct path through the curves of the colon. However, as the colonoscope is inserted farther and farther into the colon, it becomes more difficult to advance the colonoscope along the selected path. At each turn, the wall of the colon must maintain the curve in the colonoscope. The colonoscope rubs against the mucosal surface of the colon along the outside of each turn. Friction and slack in the colonoscope build up at each turn, making it more and more difficult to advance and withdraw the colonoscope. In addition, the force against the wall of the colon increases with the buildup of friction. In cases of extreme tortuosity, it may become impossible to advance the colonoscope all of the way through the colon. 
         [0005]    Steerable endoscopes, catheters and insertion devices for medical examination or treatment of internal body structures are described in the following U.S. patents, the disclosures of which are hereby incorporated by reference in their entirety: U.S. Pat. Nos. 4,753,223; 5,337,732; 5,662,587; 4,543,090; 5,383,852; 5,487,757 and 5,337,733. 
       SUMMARY OF THE INVENTION 
       [0006]    In keeping with the foregoing discussion, the present invention takes the form of a steerable endoscope for negotiating tortuous paths through a patient&#39;s body. The steerable endoscope can be used for a variety of different diagnostic and interventional procedures, including colonoscopy, bronchoscopy, thoracoscopy, laparoscopy and video endoscopy. The steerable endoscope is particularly well suited for negotiating the tortuous curves encountered when performing a colonoscopy procedure. 
         [0007]    The steerable endoscope has an elongated body with a manually or selectively steerable distal portion and an automatically controlled proximal portion. The selectively steerable distal portion can be selectively steered or bent up to a full 180 degree bend in any direction. A fiberoptic imaging bundle and one or more illumination fibers extend through the body from the proximal end to the distal end. Alternatively, the endoscope can be configured as a video endoscope with a miniaturized video camera, such as a CCD camera, which transmits images to a video monitor by a transmission cable or by wireless transmission. Optionally, the endoscope may include one or two instrument channels that may also be used for insufflation or irrigation. 
         [0008]    A proximal handle attached to the elongate body includes an ocular for direct viewing and/or for connection to a video camera, a connection to an illumination source and one or more luer lock fittings that are connected to the instrument channels. The handle is connected to a steering control for selectively steering or bending the selectively steerable distal portion in the desired direction and to an electronic motion controller for controlling the automatically controlled proximal portion of the endoscope. An axial motion transducer is provided to measure the axial motion of the endoscope body as it is advanced and withdrawn. Optionally, the endoscope may include a motor or linear actuator for automatically advancing and withdrawing the endoscope. 
         [0009]    The method of the present invention involves inserting the distal end of the endoscope body into a patient, either through a natural orifice or through an incision, and steering the selectively steerable distal portion to select a desired path. When the endoscope body is advanced, the electronic motion controller operates the automatically controlled proximal portion of the body to assume the selected curve of the selectively steerable distal portion. This process is repeated by selecting another desired path with the selectively steerable distal portion and advancing the endoscope body again. As the endoscope body is further advanced, the selected curves propagate proximally along the endoscope body. Similarly, when the endoscope body is withdrawn proximally, the selected curves propagate distally along the endoscope body. This creates a sort of serpentine motion in the endoscope body that allows it to negotiate tortuous curves along a desired path through or around and between organs within the body. 
         [0010]    The method can be used for performing colonoscopy or other endoscopic procedures, such as bronchoscopy, thoracoscopy, laparoscopy and video endoscopy. In addition, the apparatus and methods of the present invention can be used for inserting other types of instruments, such as surgical instruments, catheters or introducers, along a desired path within the body. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  shows a prior art colonoscope being employed for a colonoscopic examination of a patient&#39;s colon. 
           [0012]      FIG. 2  shows a first embodiment of the steerable endoscope of the present invention. 
           [0013]      FIG. 3  shows a second embodiment of the steerable endoscope of the present invention. 
           [0014]      FIG. 4  shows a third embodiment of the steerable endoscope of the present invention. 
           [0015]      FIG. 5  shows a fourth embodiment of the steerable endoscope of the present invention. 
           [0016]      FIG. 6  shows a wire frame model of a section of the body of the endoscope in a neutral or straight position. 
           [0017]      FIG. 7  shows the wire frame model of the endoscope body shown in  FIG. 6  passing through a curve in a patient&#39;s colon. 
           [0018]      FIG. 8  shows the endoscope of the present invention being employed for a colonoscopic examination of a patient&#39;s colon. 
           [0019]      FIG. 9  shows the endoscope of the present invention being employed for a colonoscopic examination of a patient&#39;s colon. 
           [0020]      FIG. 10  shows the endoscope of the present invention being employed for a colonoscopic examination of a patient&#39;s colon. 
           [0021]      FIG. 11  shows the endoscope of the present invention being employed for a colonoscopic examination of a patient&#39;s colon. 
           [0022]      FIG. 12  shows the endoscope of the present invention being employed for a colonoscopic examination of a patient&#39;s colon. 
           [0023]      FIG. 13  shows the endoscope of the present invention being employed for a colonoscopic examination of a patient&#39;s colon. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]      FIG. 1  shows a prior art colonoscope  500  being employed for a colonoscopic examination of a patient&#39;s colon C. The colonoscope  500  has a proximal handle  506  and an elongate body  502  with a steerable distal portion  504 . The body  502  of the colonoscope  500  has been lubricated and inserted into the colon C via the patient&#39;s anus A. Utilizing the steerable distal portion  504  for guidance, the body  502  of the colonoscope  500  has been maneuvered through several turns in the patient&#39;s colon C to the ascending colon G. Typically, this involves a considerable amount of manipulation by pushing, pulling and rotating the colonoscope  500  from the proximal end to advance it through the turns of the colon C. After the steerable distal portion  504  has passed, the wall of the colon C maintains the curve in the flexible body  502  of the colonoscope  500  as it is advanced. Friction develops along the body  502  of the colonoscope  500  as it is inserted, particularly at each turn in the colon C. Because of the friction, when the user attempts to advance the colonoscope  500 , the body  502 ′ tends to move outward at each curve, pushing against the wall of the colon C, which exacerbates the problem by increasing the friction and making it more difficult to advance the colonoscope  500 . On the other hand, when the colonoscope  500  is withdrawn, the body  502 ″ tends to move inward at each curve taking up the slack that developed when the colonoscope  500  was advanced. When the patient&#39;s colon C is extremely tortuous, the distal end of the body  502  becomes unresponsive to the user&#39;s manipulations, and eventually it may become impossible to advance the colonoscope  500  any farther. In addition to the difficulty that it presents to the user, tortuosity of the patient&#39;s colon also increases the risk of complications, such as intestinal perforation. 
         [0025]      FIG. 2  shows a first embodiment of the steerable endoscope  100  of the present invention. The endoscope  100  has an elongate body  102  with a manually or selectively steerable distal portion  104  and an automatically controlled proximal portion  106 . The selectively steerable distal portion  104  can be selectively steered or bent up to a full 180 degree bend in any direction. A fiberoptic imaging bundle  112  and one or more illumination fibers  114  extend through the body  102  from the proximal end  110  to the distal end  108 . Alternatively, the endoscope  100  can be configured as a video endoscope with a miniaturized video camera, such as a CCD camera, positioned at the distal end  108  of the endoscope body  102 . The images from the video camera can be transmitted to a video monitor by a transmission cable or by wireless transmission. Optionally, the body  102  of the endoscope  100  may include one or two instrument channels  116 ,  118  that may also be used for insufflation or irrigation. The body  102  of the endoscope  100  is highly flexible so that it is able to bend around small diameter curves without buckling or kinking. When configured for use as a colonoscope, the body  102  of the endoscope  100  is typically from 135 to 185 cm in length and approximately 12-13 mm in diameter. The endoscope  100  can be made in a variety of other sizes and configurations for other medical and industrial applications. 
         [0026]    A proximal handle  120  is attached to the proximal end  110  of the elongate body  102 . The handle  120  includes an ocular  124  connected to the fiberoptic imaging bundle  112  for direct viewing and/or for connection to a video camera  126 . The handle  120  is connected to an illumination source  128  by an illumination cable  134  that is connected to or continuous with the illumination fibers  114 . A first luer lock fitting,  130  and a second luer lock fitting  132  on the handle  120  are connected, to the instrument channels  116 ,  118 . 
         [0027]    The handle  120  is connected to an electronic motion controller  140  by way of a controller cable  136 . A steering control  122  is connected to the electronic motion controller  140  by way of a second cable  13  M. The steering control  122  allows the user to selectively steer or bend the selectively steerable distal portion  104  of the body  102  in the desired direction. The steering control  122  may be a joystick controller as shown, or other known steering control mechanism. The electronic motion controller  140  controls the motion of the automatically controlled proximal portion  106  of the body  102 . The electronic motion controller  140  may be implemented using a motion control program running on a microcomputer or using an application-specific motion controller. Alternatively, the electronic motion controller  140  may be implemented using a neural network controller. 
         [0028]    An axial motion transducer  150  is provided to measure the axial motion of the endoscope body  102  as it is advanced and withdrawn. The axial motion transducer  150  can be made in many possible configurations. By way of example, the axial motion transducer  150  in  FIG. 2  is configured as a ring  152  that surrounds the body  102  of the endoscope  100 . The axial motion transducer  150  is attached to a fixed point of reference, such as the surgical table or the insertion point for the endoscope  100  on the patient&#39;s body. As the body  102  of the endoscope  100  slides through the axial motion transducer  150 , it produces a signal indicative of the axial position of the endoscope body  102  with respect to the fixed point of reference and sends a signal to the electronic motion controller  140  by telemetry or by a cable (not shown). The axial motion transducer  150  may use optical, electronic or mechanical means to measure the axial position of the endoscope body  102 . Other possible configurations for the axial motion transducer  150  are described below. 
         [0029]      FIG. 3  shows a second embodiment of the endoscope  100  of the present invention. As in the embodiment of  FIG. 2 , the endoscope  100  has an elongate body  102  with a selectively steerable distal portion  104  and an automatically controlled proximal portion  106 . The steering control  122  is integrated into proximal handle  120  in the form of one or two dials for selectively steering the selectively steerable distal portion  104  of the endoscope  100 . Optionally, the electronic motion controller  140  may be miniaturized and integrated into proximal handle  120 , as well. In this embodiment, the axial motion transducer  150  is configured with a base  154  that is attachable to a fixed point of reference, such as the surgical table. A first roller  156  and a second roller  158  contact the exterior of the endoscope body  102 . A multi-turn potentiometer  160  or other motion transducer is connected to the first roller  156  to measure the axial motion of the endoscope body  102  and to produce a signal indicative of the axial position. 
         [0030]    The endoscope  100  may be manually advanced or withdrawn by the user by grasping the body  102  distal to the axial motion transducer  150 . Alternatively, the first roller  156  and/or second roller  158  may be connected to a motor  162  for automatically advancing and withdrawing the body  102  of the endoscope  100 . 
         [0031]      FIG. 4  shows a third embodiment of the endoscope  100  of the present invention, which utilizes an elongated housing  170  to organize and contain the endoscope  100 . The housing  170  has a base  172  with a linear track  174  to guide the body  102  of the endoscope  100 . The housing  170  may have an axial motion transducer  150 ′ that is configured as a linear motion transducer integrated into the linear track  174 . Alternatively, the housing,  170  may have an axial motion transducer  150 ″ configured similarly to the axial motion transducer  150  in  FIG. 2  or  3 . The endoscope  100  may be manually advanced or withdrawn by the user by grasping the body  102  distal to the housing  170 . Alternatively, the housing  170  may include a motor  176  or other linear motion actuator for automatically advancing and withdrawing the body  102  of the endoscope  100 . In another alternative configuration, a motor with friction wheels, similar to that described above in connection with  FIG. 3 , may be integrated into the axial motion transducer  150 ″. 
         [0032]      FIG. 5  shows a fourth embodiment of the endoscope  100  of the present invention, which utilizes a rotary housing  180  to organize and contain the endoscope  100 . The housing  180  has a base  182  with a rotating drum  184  to guide the body  102  of the endoscope  100 . The housing  180  may have an axial motion transducer  150 ′″ that is configured as a potentiometer connected to the pivot axis  186  of the rotating drum  184 . Alternatively, the housing  180  may have an axial motion transducer  150 ′″ configured similarly to the axial motion transducer  150  in  FIG. 2  or  3 . The endoscope  100  may be manually advanced or withdrawn by the user by grasping the body  102  distal to the housing  180 . Alternatively, the housing  180  may include a motor  188  connected to the rotating drum  184  for automatically advancing and withdrawing the body  102  of the endoscope  100 . In another alternative configuration, a motor with friction wheels, similar to that described above in connection with  FIG. 3 , may be integrated into the axial motion transducer  150 ″. 
         [0033]      FIG. 6  shows a wire frame model of a section of the body  102  of the endoscope  100  in a neutral or straight position. Most of the internal structure of the endoscope body  102  has been eliminated in this drawing for the sake of clarity. The endoscope body  102  is divided up into sections  1 ,  2 ,  3  . . .  10 , etc. The geometry of each section is defined by four length measurements along the a, b, c and d axes. For example, the geometry of section  1  is defined by the four length measurements l 1a , l 1b ,  1   1c , l 1d , and the geometry of section  2  is defined by the four length measurements l 2a , l 2b  l 2b , l 2d , etc. Preferably, each of the length measurements is individually controlled by a linear actuator (not shown). The linear actuators may utilize one of several different operating principles. For example, each of the linear actuators may be a self-heating NiTi alloy linear actuator or an electrorheological plastic actuator, or other known mechanical, pneumatic, hydraulic or electromechanical actuator. The geometry of each section may be altered using the linear actuators to change the four length measurements along the a, b, c and d axes. Preferably, the length measurements are changed in complementary pairs to selectively bend the endoscope body  102  in a desired direction. For example, to bend the endoscope body  102  in the direction of the a axis, the measurements l 1a , l 2a , l 13a  . . . l 10a  would be shortened and the measurements l 1b , l 2b  l 3b  . . . l 10b  would be lengthened an equal amount. The amount by which these measurements are changed determines the radius of the resultant curve. 
         [0034]    In the selectively steerable distal portion  104  of the endoscope body  102 , the linear actuators that control the a, b, c and d axis measurements of each section are selectively controlled by the user through the steering control  122 . Thus, by appropriate control of the a, b, c and d axis measurements, the selectively steerable distal portion  104  of the endoscope body  102  can be selectively steered or bent up to a full 180 degrees in any direction. 
         [0035]    In the automatically controlled proximal portion  106 , however, the a, b, c and d axis measurements of each section are automatically controlled by the electronic motion controller  140 , which uses a curve propagation method to control the shape of the endoscope body  102 . To explain how the curve propagation method operates,  FIG. 7  shows the wire frame model of a part of the automatically controlled proximal portion  106  of the endoscope body  102  shown in  FIG. 6  passing through a curve in a patient&#39;s colon C. For simplicity, an example of a two-dimensional curve is shown and only the a and b axes will be considered. In a three-dimensional curve all four of the a, b, c and d axes would be brought into play. 
         [0036]    In  FIG. 7 , the endoscope body  102  has been maneuvered through the curve in the colon C with the benefit of the selectively steerable distal portion  104  (this part of the procedure is explained in more detail below) and now the automatically controlled proximal portion  106  resides in the curve. Sections  1  and  2  are in a relatively straight part of the colon C, therefore l 1a =l 1b  and l 2a =l 2b . However, because sections  3 - 7  are in the S-shaped curved section, l 3a &lt;l 3b , l 4a &lt;l 4b  and l 5a &lt;l 5b , but l 6a &gt;l 6b , l 7a &gt;l 7b  and l 8a &gt;l 8b . When the endoscope body  102  is advanced distally by one unit, section  1  moves into the position marked  1 ′, section  2  moves into the position previously occupied by section  1 , section  3  moves into the position previously occupied by section  2 , etc. The axial motion transducer  150  produces a signal indicative of the axial position of the endoscope body  102  with respect to a fixed point of reference and sends the signal to the electronic motion controller  140 . Under control of the electronic motion controller  140 , each time the endoscope body  102  advances one unit, each section in the automatically controlled proximal portion  106  is signaled to assume the shape of the section that previously occupied the space that it is now in. Therefore, when the endoscope body  102  is advanced to the position marked  1 ′, l 1a =l 1b , l 2a =l 2b , l 3a =l 3b , l 4a &lt;l 4b , l 5a &lt;l 5b , l 6a &lt;l 6b , l 7a &gt;l 7b  and l 8a &gt;l 8b , and l 9a &gt;l 9b , when the endoscope body  102  is advanced to the position marked  1 ″, l 1a =l 1b , l 2a =l 2b , l 3a =l 3b , l 4a =l 4b , l 5a &lt;l 5b , l 6a &lt;l 6b , l 7a &lt;l 7b , l 8a &gt;l 8b , l 9a &gt;l 9b  and l 10a &gt;l 10b . Thus, the S-shaped curve propagates proximally along the length of the automatically controlled proximal portion  106  of the endoscope body  102 . The S-shaped curve appears to be fixed in space, as the endoscope body  102  advances distally. 
         [0037]    Similarly, when the endoscope body  102  is withdrawn proximally, each time the endoscope body  102  is moved proximally by one unit, each section in the automatically controlled proximal portion  106  is signaled to assume the shape of the section that previously occupied the space that it is now in. The S-shaped curve propagates distally along the length of the automatically controlled proximal portion  106  of the endoscope body  102 , and the S-shaped curve appears to be fixed in space, as the endoscope body  102  withdraws proximally. 
         [0038]    Whenever the endoscope body  102  is advanced or withdrawn, the axial motion transducer  150  detects the change in position and the electronic motion controller  140  propagates the selected curves proximally or distally along the automatically controlled proximal portion  106  of the endoscope body  102  to maintain the curves in a spatially fixed position. This allows the endoscope body  102  to move through tortuous curves without putting unnecessary force on the wall of the colon C. 
         [0039]      FIGS. 8-13  show the endoscope  100  of the present invention being employed for a colonoscopic examination of a patient&#39;s colon. In  FIG. 8 , the endoscope body  102  has been lubricated and inserted into the patient&#39;s colon C through the anus A. The distal end  108  of the endoscope body  102  is advanced through the rectum R until the first tum in the colon C is reached, as observed through the ocular  124  or on a video monitor. To negotiate the turn, the selectively steerable distal portion  104  of the endoscope body  102  is manually steered toward the sigmoid colon S by the user through the steering control  122 . The control signals from the steering control  122  to the selectively steerable distal portion  104  are monitored by the electronic motion controller  140 . When the correct curve of the selectively steerable distal portion  104  for advancing the distal end  108  of the endoscope body  102  into the sigmoid colon S has been selected, the curve is logged into the memory of the electronic motion controller  140  as a reference. This step can be performed in a manual mode, in which the user gives a command to the electronic motion controller  140  to record the selected curve, using keyboard commands or voice commands. Alternatively, this step can be performed in an automatic mode, in which the user signals to the electronic motion controller  140  that the desired curve has been selected by advancing the endoscope body  102  distally. 
         [0040]    Whether operated in manual mode or automatic mode, once the desired curve has been selected with the selectively steerable distal portion  104 , the endoscope body  102  is advanced distally and the selected curve is propagated proximally along the automatically controlled proximal portion  106  of the endoscope body  102  by the electronic motion controller  140 , as described above. The curve remains fixed in space while the endoscope body  102  is advanced distally through the sigmoid colon S. In a particularly tortuous colon, the selectively steerable distal portion  104  may have to be steered through multiple curves to traverse the sigmoid colon S. 
         [0041]    As illustrated in  FIG. 9 , the user may stop the endoscope  100  at any point for examination or treatment of the mucosal surface or any other features within the colon C. The selectively steerable distal portion  104  may be steered in any direction to examine the inside of the colon C. When the user has completed the examination of the sigmoid colon S, the selectively steerable distal portion  104  is steered in a superior direction toward the descending colon D. Once the desired curve has been selected with the selectively steerable distal portion  104 , the endoscope body  102  is advanced distally into the descending colon D, and the second curve as well as the first curve are propagated proximally along the automatically controlled proximal portion  106  of the endoscope body  102 , as shown in  FIG. 10 . 
         [0042]    If, at any time, the user decides that the path taken by the endoscope body  102  needs to be revised or corrected, the endoscope  100  may be withdrawn proximally and the electronic motion controller  140  commanded to erase the previously selected curve. This can be done manually using keyboard commands or voice commands or automatically by programming the electronic motion controller  140  to go into a revise mode when the endoscope body  102  is withdrawn a certain distance. The revised or corrected curve is selected using the selectively steerable distal portion  104 , and the endoscope body  102  is advanced as described before. 
         [0043]    The endoscope body  102  is advanced through the descending colon D until it reaches the left (splenic) flexure F I  of the colon. Here, in many cases, the endoscope body  102  must negotiate an almost 180 degree hairpin turn. As before, the desired curve is selected using the selectively steerable distal portion  104 , and the endoscope body  102  is advanced distally through the transverse colon T, as shown in  FIG. 11 . Each of the previously selected curves is propagated proximally along the automatically controlled proximal portion  106  of the endoscope body  102 . The same procedure is followed at the right (hepatic) flexure F r  of the colon and the distal end  108  of the endoscope body  102  is advanced through the ascending colon G to the cecum E, as shown in  FIG. 12 . The cecum E, the ileocecal valve V and the terminal portion of the ileum I can be examined from this point using the selectively steerable distal portion  104  of the endoscope body  102 . 
         [0044]      FIG. 13  shows the endoscope  100  being withdrawn through the colon C. As the endoscope  100  is withdrawn, the endoscope body  102  follows the previously selected curves by propagating the curves distally along the automatically controlled proximal portion  106 , as described above. At any point, the user may stop the endoscope  100  for examination or treatment of the mucosal surface or any other features within the colon C using the selectively steerable distal portion  104  of the endoscope body  102 . 
         [0045]    In one preferred method according to the present invention, the electronic motion controller  140  includes an electronic memory in which is created a three-dimensional mathematical model of the patient&#39;s colon or other anatomy through which the endoscope body  102  is maneuvered. The three-dimensional model can be annotated by the operator to record the location of anatomical landmarks, lesions, polyps, biopsy samples and other features of interest. The three-dimensional model of the patient&#39;s anatomy can be used to facilitate reinsertion of the endoscope body  102  in subsequent procedures. In addition, the annotations can be used to quickly find the location of the features of interest. For example, the three-dimensional model can be annotated with the location where a biopsy sample was taken during an exploratory endoscopy. The site of the biopsy sample can be reliably located again in follow-up procedures to track the progress of a potential disease process and/or to perform a therapeutic procedure at the site. 
         [0046]    In one particularly preferred variation of this method, the electronic motion controller  140  can be programmed, based on the three-dimensional model in the electronic memory, so that the endoscope body  102  will automatically assume the proper shape to follow the desired path as it is advanced through the patient&#39;s anatomy. In embodiments of the steerable endoscope  100  that are configured for automatically advancing and withdrawing the endoscope body  102 , as described above in connection with  FIGS. 3 ,  4  and  5 , the endoscope body  102  can be commanded to advance automatically through the patient&#39;s anatomy to the site of a previously noted lesion or other point of interest based on the three-dimensional model in the electronic memory. 
         [0047]    Imaging software would allow the three-dimensional model of the patient&#39;s anatomy obtained using the steerable endoscope  100  to be viewed on a computer monitor or the like. This would facilitate comparisons between the three dimensional model and images obtained with other imaging modalities, for example fluoroscopy, radiography, ultrasonography, magnetic resonance imaging (MRI), computed tomography (CT scan), electron beam tomography or virtual colonoscopy. Conversely, images from these other imaging modalities can be used to map out an approximate path or trajectory to facilitate insertion of the endoscope body  102 . In addition, images from other imaging modalities can be used to facilitate locating suspected lesions with the steerable endoscope  100 . For example, images obtained using a barium-contrast radiograph of the colon can be used to map out an approximate path to facilitate insertion of the endoscope body  102  into the patient&#39;s colon. The location and depth of any suspected lesions seen on the radiograph can be noted so that the endoscope body  102  can be quickly and reliably guided to the vicinity of the lesion. 
         [0048]    Imaging modalities that provide three-dimensional information, such as biplanar fluoroscopy, CT or MRI, can be used to program the electronic motion controller  140  so that the endoscope body  102  will automatically assume the proper shape to follow the desired path as it is advanced through the patient&#39;s anatomy. In embodiments of the steerable endoscope  100  that are configured for automatically advancing and withdrawing the endoscope body  102 , the endoscope body  102  can be commanded to advance automatically though the patient&#39;s anatomy along the desired path as determined by the three-dimensional information. Similarly, the endoscope body  102  can be commanded to advance automatically to the site of a suspected lesion or other point of interest noted on the images. 
         [0049]    Although the endoscope of the present invention has been described for use as a colonoscope, the endoscope can be configured for a number of other medical and industrial applications. In addition, the present invention can also be configured as a catheter, cannula, surgical instrument or introducer sheath that uses the principles of the invention for navigating through tortuous body channels. 
         [0050]    In a variation of the method that is particularly applicable to laparoscopy or thoracoscopy procedures, the steerable endoscope  100  can be selectively maneuvered along a desired path around and between organs in a patient&#39;s body cavity. The distal end  108  of the endoscope  100  is inserted into the patient&#39;s body cavity through a natural opening, through a surgical incision or through a surgical cannula or introducer. The selectively steerable distal portion  104  can be used to explore and examine the patient&#39;s body cavity and to select a path around and between the patient&#39;s organs. The electronic motion controller  140  can be used to control the automatic controlled proximal portion  106  of the endoscope body  102  to follow the selected path and, if necessary, to return to a desired location using the three-dimensional model in the electronic memory of the electronic motion controller  140 . 
         [0051]    While the present invention has been described herein with respect to the exemplary embodiments and the best mode for practicing the invention, it will be apparent to one of ordinary skill in the art that man modifications, improvements and subcombinations of the various embodiments, adaptations and variations can be made to the invention without departing from the spirit and scope thereof.