Abstract:
An imaging system comprising an imaging device assembled on a carrier tube, and a first outwardly expandable element and a second outwardly expandable element mounted on the carrier tube, wherein the second expandable element is expandable both radially and axially, the imaging system comprising a mode of operation, wherein during expansion of the second expandable element, obstruction of the radial expansion of the second expandable element causes the axial expansion of the second expandable element to propel the carrier tube and the imaging device axially.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to medical imaging systems, and particularly to a self-propelled imaging system, suitable for imaging body lumens, such as the gastrointestinal (GI) tract.  
         BACKGROUND OF THE INVENTION  
         [0002]    Many imaging devices are known for producing medical images of body lumens, such as the gastrointestinal (GI) tract. For example, endoscopy is widely used for observing, photographing tissue, and taking specimens from lesions and the like. In a conventional method of examining a colon using an endoscope, for example, the endoscope is typically manually inserted into the colon. In this manual technique, patients may often complain of abdominal pain and distention because the colon is extended or excessively dilated, thereby necessitating stopping the endoscopic procedure. Furthermore, it is not unusual for the colon to bleed and be accidentally perforated. Insertion of an endoscope through the sigmoid colon and into the descending colon, or through the splenic flexure, the transverse colon, the hepatic flexure or parts affected by previous operations may also be accompanied with difficulty. Because of these reasons, a colonoscopy is typically performed by a relatively few number of skilled practitioners, and the rate of patient pain and discomfort is high.  
           [0003]    U.S. Pat. No. 5,337,732 to Grundfest et al. describes a robot for performing endoscopic procedures, which includes a plurality of segments attached to each other through an articulated joint. Actuators can move the segments together and apart and change their angular orientation to allow the robot to move in an inchworm or snake-like fashion through a cavity or lumen within a patient. Inflatable balloons around the segments inflate to brace a temporarily stationary segment against the lumen walls while other segments move. A compressed gas line attached to the back segment provides compressed gas to inflate the balloons and optionally to drive the actuators. The lead segment includes a television camera and biopsy arm or other sensors and surgical instruments.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention seeks to provide an improved imaging system which is self-propelled, suitable for imaging body lumens, such as the gastrointestinal (GI) tract. The imaging system of the invention may be sterile and disposable, and may be manufactured at very low cost. The system causes virtually no pain to the patient, being of very low friction and providing maximum comfort and flexibility. The system provides excellent visibility and full movement control.  
           [0005]    The imaging system of the present invention may comprise an imaging device assembled on a carrier tube. First and second outwardly expandable elements may be mounted on the carrier tube. The second expandable element may be expanded both radially and axially. In one mode of operation, in accordance with an embodiment of the invention, during expansion of the second expandable element, obstruction of the radial expansion of the second expandable element (such as when the second expandable element presses against the inner wall of a body lumen) causes the axial expansion of the second expandable element to propel the carrier tube and the imaging device axially, as is described more in detail hereinbelow. The imaging system may thus self-propel distally into the body lumen without any need for knowing the local diameter of the body lumen. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings in which:  
         [0007]    [0007]FIG. 1A is a simplified pictorial and cut-away illustration of an imaging system, constructed and operative in accordance with an embodiment of the present invention, in a contracted orientation;  
         [0008]    [0008]FIG. 1B is a simplified pictorial illustration of a distal end of the imaging system of FIG. 1A;  
         [0009]    [0009]FIG. 1C is a simplified sectional illustration of the imaging system of FIG. 1A;  
         [0010]    FIGS.  1 D- 1 G are simplified pictorial illustrations of the imaging system of FIG. 1A, showing four steps of a mode of operation thereof, wherein in FIG. 1D a proximal expandable element and a distal expandable element are both contracted, in FIG. 1E the proximal expandable element expands generally spherically, in FIG. 1F the distal and proximal expandable elements are both expanded, and in FIG. 1G the distal expandable element is expanded while the proximal expandable element is contracted;  
         [0011]    [0011]FIG. 2 is a simplified side-view illustration of the imaging system of FIG. 1A inserted in a body lumen in a contracted orientation, prior to self-propulsion therethrough, in accordance with an embodiment of the present invention;  
         [0012]    [0012]FIG. 3 is a simplified side-view illustration of the imaging system of FIG. 1A with the proximal expandable element partially expanded and not yet touching the inner wall of the body lumen;  
         [0013]    [0013]FIG. 4 is a simplified side-view illustration of the imaging system of FIG. 1A with the proximal expandable element further expanded and touching the inner wall of the body lumen;  
         [0014]    [0014]FIG. 5 is a simplified side-view illustration of the imaging system of FIG. 1A with the proximal expandable element further expanded, pressing against the inner wall of the body lumen, and propelling the imaging system distally through the body lumen;  
         [0015]    [0015]FIG. 6 is a simplified pictorial and cut-away illustration of the imaging system of FIG. 1A in the orientation of FIG. 4 or  5 ;  
         [0016]    [0016]FIG. 7 is a simplified pictorial and cut-away illustration of the imaging system of FIG. 1A with the proximal expandable element expanded and a distal expandable element also expanded, in accordance with an embodiment of the present invention; and  
         [0017]    [0017]FIG. 8 is a simplified pictorial and cut-away illustration of the imaging system of FIG. 1A with the proximal expandable element contracted and the distal expandable element expanded, in accordance with an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0018]    Reference is now made to FIG. 1A, which illustrates an imaging system  10 , constructed and operative in accordance with a preferred embodiment of the present invention.  
         [0019]    Imaging system  10  may comprise first and second outwardly expandable elements  12  and  14 . One of the outwardly expandable elements may be the proximal element and the other one may be the distal element. For example, in terms of the explanation that follows with reference to FIGS.  2 - 8 , first element  12  is the distal element that enters the body lumen first, and second element  14  is the proximal element that enters the body lumen last.  
         [0020]    In accordance with a preferred embodiment of the present invention, first and second expandable elements  12  and  14  expand to different shapes. First expandable element  12  may expand substantially radially with negligible axial expansion. In contrast, second expandable element  14  may expand both radially and axially, such as expanding generally spherically.  
         [0021]    First and second expandable elements  12  and  14  may be mounted coaxially on a carrier tube  16 . Carrier tube  16  may be made of any suitable, flexible, medically approved material. The expandable elements  12  and  14  may comprise full circumference or partial circumference elements.  
         [0022]    Each expandable element  12  or  14  may comprise an inflatable, elastomeric tubular element formed with annular rings  18 . Each expandable element  12  or  14  may be mounted in a pair of collar elements  20 , wherein the annular rings  18  are received in annular grooves  22  formed in collar elements  20 . Annular ring  18  may be held in groove  22  by means of an annular fastener  21 , which snaps together with tongues  19  axially protruding from collar element  20 . Collar elements  20  may be formed separately for each expandable element, and may be adjoined together by snapping together or by means of fasteners or any other suitable method. Alternatively, a single collar element  20  may be placed between first and second expandable elements  12  and  14 , wherein the single collar element  20  has two sets of annular grooves  22  to receive therein the proximal annular ring  18  of the distal expandable element  12  and the distal annular ring  18  of the proximal expandable element  14 . The collar elements  20  may be flexible and resilient to permit passage of imaging system  10  through folds of the GI tract. An O-ring  23  may slidingly seal the most proximal collar element  20  with respect to carrier tube  16 . Accordingly, the collar elements  20  at the ends of first expandable element  12  may be fixed axially with respect to carrier tube  16 , thereby preventing first expandable element  12  from expanding axially. In contrast, second expandable element  14  may slide axially relative to carrier tube  16 .  
         [0023]    In accordance with another embodiment of the invention, whether or not the collar elements  20  are fixed axially with respect to carrier tube  16  may be selectable. In this manner, a user may select which of the expandable elements may expand only radially and which may expand both radially and axially. For example, first expandable element  12  may expand both radially and axially, if desired, instead of second expandable element  14 , which may cause imaging system  10  to move in a proximal direction instead of a distal direction.  
         [0024]    Carrier tube  16  may be formed with a distal aperture  24  and a proximal aperture  26 . A first supply tube  28  may be introduced through carrier tube  16  in fluid communication with distal aperture  24 . Similarly, a second supply tube  30  may be introduced through carrier tube  16  in fluid communication with proximal aperture  26 . First expandable element  12  may be expanded outwards by introducing therein a fluid, such as but not limited to, air or water, by means of first supply tube  28  via distal aperture  24 . Likewise, second expandable element  14  may be expanded outwards by introducing therein a fluid (which may or may not be the same fluid used to expand first expandable element  12 ), by means of second supply tube  30  via proximal aperture  26 .  
         [0025]    Reference is now made to FIGS. 1B and 1C. An imaging device  32 , such as but not limited to, a CCD (charge coupled device) or CMOS (complementary metal oxide semiconductor) camera, may be mounted at a distal end of imaging system  10 . For example, imaging device  32  may be mounted in the most distal collar element  20 , which may be formed with a viewing window  34  through which images may be captured. Imaging device  32  and viewing window  34  may be oriented for capturing images either axially or radially with respect to carrier tube  16 . A light source  36  may be provided for imaging device  18 , wherein electrical wiring and/or optic fibers  38  (FIG. 1C) may be fed through carrier tube  16  to imaging device  32  and light source  36 .  
         [0026]    Imaging device  32  may be connected to an imaging processor (not shown) by optical fibers. A control system (not shown) may be provided that oversees and controls the expansion/contraction of the expandable elements  12  and  14 , and other functions of imaging system  10 , such as but not limited to, the timing and amount of the expansion/contraction of the expandable elements  12  and  14 .  
         [0027]    Other tubes or passageways may be provided for other functionalities. For example, a suction tube  40  (FIG. 1B) may be provided for sucking debris or other material. A tool lumen  42  may be provided for introducing therethrough mechanical devices and/or sensors (not shown), such as but not limited to, cutting devices for cutting and collecting materials for biopsies and the like, and biosensors. Additionally, passageways  44  may be provided for passing therethrough control wires  46  for directing the imaging system  10  through tight bends and the like.  
         [0028]    A guide member  50  (FIG. 1C) may be disposed at the proximal end of carrier tube  16 . Guide member  50  may be funnel-shaped, for example, for comfortable placement in a rectum of a patient (not shown). A linear encoder  52  may be disposed at the proximal end of carrier tube  16  and pass through guide member  50 . Linear encoder  52  may comprise markings and the like detectable by a decoder  54  mounted on guide member  50 . Decoder  54  may sense linear movement of carrier tube  16  with respect to linear encoder  52 , which movement is described in greater detail hereinbelow.  
         [0029]    It is noted that the electrical and optical components may be self-contained in imaging system  10 , so that the entire system  10  is fully independent of external wiring. In such an embodiment, imaging system  10  may wirelessly transmit or receive data to or from an external processor (not shown).  
         [0030]    Reference is now made to FIGS.  1 D- 1 G and FIGS.  2 - 5 , which illustrate imaging system  10  in different orientations for self-propulsion through a body lumen  60 , such as but not limited to, the colon, in accordance with an embodiment of the present invention. (The body lumen  60  is omitted in FIGS.  1 D- 1 G for clarity.) In the initial orientation of FIGS. 1D and 2, none of the expandable elements  12  and  14  are expanded, as in FIG. 1A. In this contracted orientation, imaging system  10  may be inserted in body lumen  60 . In FIG. 3, second (proximal) expandable element  14  may be expanded outwardly. As seen in FIG. 3, before the proximal expandable element  14  touches the inner wall of body lumen  60 , it may expand both radially and axially (e.g., spherically). O-ring  23  slides proximally along carrier tube  16 , as indicated by arrow  53 , with the result that carrier tube  16  (along with imaging device  32 ) does not yet advance in body lumen  60 .  
         [0031]    In FIG. 4, the proximal expandable element  14  has expanded sufficiently so that it touches the inner wall of body lumen  60 . Carrier tube  16  (along with imaging device  32 ) has still not advanced in body lumen  60 , and O-ring  23  has continued to slide proximally along carrier tube  16 , as indicated by arrow  53 . The orientation of FIG. 4 is shown in pictorially in FIG. 6.  
         [0032]    In FIG. 5, the proximal expandable element  14  continues to expand. Since the proximal expandable element  14  has already contacted the inner wall of body lumen  60 , the continued expansion of expandable element  14  presses it against the inner wall of body lumen  60 . The friction between expandable element  14  and the inner wall resists the radial expansion, with the result that most of the expansion of the proximal expandable element  14  is in the axial direction, as indicated by double arrow  57 . This causes carrier tube  16  (along with imaging device  32 ) to advance distally in body lumen  60 , as indicated by arrow  62 , by a distance  6  in FIG. 5. The distal advancement of carrier tube  16  relative to guide member  50  may be detected by linear encoder  52  and decoder  54  (seen also in FIG. 1E).  
         [0033]    Thus the expansion of second expandable element  14  may advance the carrier tube  16  distally in body lumen  60 , without any need for sensing when second expandable element  14  has actually contacted the inner wall of body lumen  60 . Rather once second expandable element  14  presses against the inner wall of body lumen  60 , further expansion of second expandable element  14  may advance the carrier tube  16  distally in body lumen  60 . The control system may control the further expansion of second expandable element  14  in order to control the amount of incremental advancement of carrier tube  16  and imaging device  32 .  
         [0034]    In FIGS. 1F and 7, first (distal) expandable element  12  may be expanded radially. Both first and second expandable elements  12  and  14  now press against the inner wall of body lumen  60  (not shown in FIG. 7) and fix imaging system  10  in place in lumen  60 . In FIGS. 1G and 8, second expandable element  14  may be contracted inwardly (e.g., deflated) so that it no longer presses against the inner wall of body lumen  60  (not shown in FIG. 8). Images may be captured by imaging device  32  at either of the orientations shown in FIGS. 7 and 8. As seen best in FIG. 1G, second expandable element  14  advances distally along carrier tube  16  when it is contracted inwardly, as indicated by arrow  67 .  
         [0035]    In order to advance carrier tube  16  further distally, first expandable element  12  may be contracted so that imaging system  10  returns to the contracted orientation of FIG. 2, and the operating cycle may be repeated to incrementally advance imaging system  10  through body lumen  60 . The user or control system may ensure that carrier tube  16  does not move back proximally at each increment distal advance. Alternatively, as another way of ensuring that carrier tube  16  does not move back proximally at each incremental distal advance, first expandable element  12  may initially remain expanded against the inner wall of body lumen  60  while re-expanding second expandable element  14 , and then first expandable element  12  may be contracted so as not to impede the incremental distal advancement caused by the re-expansion of second expandable element  14 . The control system may control the timing of the contraction of the first expandable element  12  and the expansion of the second expandable element  14 .  
         [0036]    Imaging system  10  may be contracted to the orientation of FIG. 2 for removal from body lumen  60 .  
         [0037]    It will be appreciated by person skilled in the art that the present invention is not limited by what has been particularly shown and described herein above. Rather the scope of the present invention is defined only by the claims that follow: