Patent Publication Number: US-2009240143-A1

Title: Method and an optical probe for in vivo imaging of a mucosa in a biliary or pancreatic system and a method for selectively operating a tissue sampling of a mucosa in a biliary or pancreatic system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application Ser. No. 61/035,795, filed on Mar. 12, 2008, which is fully incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Field of the Disclosure 
     The invention relates generally to in vivo imaging of a mucosa in a biliary or a pancreatic system and to tissue sampling of a mucosa in a biliary or a pancreatic system. More specifically, the mucosa may be part of any of a Vater Ampulla, a common bile duct, a common hepatic duct, a right main hepatic duct, a left main hepatic duct, a cystic duct, a pancreatic duct, a gallbladder, a pancreas and a liver. 
     2. Background Art 
     Cholangiocarcinoma is a cancer of the bile ducts, which drain bile from the liver into the small intestine. It is a relatively rare cancer, with an annual incidence of 1-2 cases per 100,000 in the Western world. However, the rates of cholangiocarcinoma have been rising worldwide over the past several decades. The symptoms of cholangiocarcinoma include jaundice, weight loss, abdominal pain and sometimes generalized itching. The disease is diagnosed through a combination of blood tests, imaging, endoscopy, and sometimes surgical exploration. Surgery is the only potentially curative treatment, but most patients have advanced and inoperable disease at the time of diagnosis. Prognosis is very poor with a 5-year survival rate of less than 20%. 
     While abdominal imaging may be useful in the diagnosis of cholangiocarcinoma, direct imaging of the bile ducts is often necessary to differentiate benign from malignant causes of biliary obstruction. Direct imaging of the pancreatic duct is similarly interesting for operating an accurate diagnosis of pancreatic cancer. Current techniques for imaging bile ducts include Endoscopic retrograde cholangiopancreatography (ERCP), an endoscopic procedure performed by a gastroenterologist, which has been widely used for this purpose. Direct cholangiopancreatography may also be accomplished via percutaneous transhepatic insertion of a needle/catheter. 
     ERCP was introduced for diagnostic evaluation of pancreaticobiliary diseases in late 60&#39;s to facilitate radiographic imaging. ERCP is an indirect diagnosis. Basic ERCP procedure consists generally of using an endoscope inserted orally into the duodenum and placing a catheter in the bile/pancreatic duct for injection of a radiographic contrast to provide X-Ray images of the ducts. The goals of ERCP are to detect presence of dilation or narrowing of ducts and to determine cause of such morphologic changes, to obtain fluid or tissue samples and cellular material, and to deliver endoscopic therapeutic interventions, such as sphincterotomy, removal of stones, or placement of stents. Since the introduction of advanced imaging methods, such as MRI and endoscopic ultrasound, ERCP becomes more and more therapeutic. To date, 20% of ERCP procedures are purely diagnostic, while 80% of such procedures are therapeutic. ERCP procedures are now rarely performed without therapeutic intent. 
     However, accurate diagnosis and staging of biliary and pancreatic cancers remains a clinical problem despite advanced imaging methods currently available. Up to 15% of all suspected cholangiocarcinomas are found to be benign bile duct alterations, the rate of RO-resections is unfavorably low, and methods for tissue sampling show low sensitivity (50%). Radiographic diagnosis of pancreaticobiliary malignancies by ERCP is sensitive but nonspecific. A definitive tissue diagnosis of malignancy may be made during ERCP by using brush cytology, fine needle aspiration, and biopsy, but with a relatively low yield unless several techniques are used at the same time. Therefore, there remains a need for a method and a device for improved diagnosis accuracy of biliary and pancreatic cancers. 
     Summary of Claimed Subject Matter 
     One aspect of the invention relates to methods for observing a mucosa of a biliary or pancreatic system in a subject. A method in accordance with one embodiment of the invention includes positioning a optical probe in contact with said mucosa, wherein the optical probe accesses the biliary or pancreatic system using a working channel of an endoscope inserted orally in the subject. 
     Another aspect of the invention relates to methods for obtaining a tissue sample from a mucosa of a biliary or pancreatic system in a subject. A method in accordance with one embodiment of the invention includes introducing orally an endoscope down to a major duodenal papilla and aligning the endoscope with the major duodenal papilla; 
     introducing a tube into a working channel of the endoscope and inserting the tube into the biliary or pancreatic system through the major duodenal papilla; introducing a optical probe into a lumen of said tube, wherein the optical probe is coupled to a microscope; observing in vivo the mucosa using the optical probe and the microscope, wherein said optical probe is positioned in contact with said mucosa; determining an area of interest on said mucosa and stabilizing the tube and the endoscope at a position close to said area; extracting the optical probe out of the lumen of said tube; inserting a tissue sampling tool in the lumen of the tube; and sampling the tissue from said area of interest. 
     Another aspect of the invention relates to optical probes to be used with a fiber optic microscopes for in vivo observation. An optical probe in accordance with one embodiment of the invention includes an optical fiber bundle, a miniaturized objective connected coaxially at a distal tip of the optical fiber bundle, wherein the optical fiber bundle and the miniaturized objective each have a diameter of less than 1.2 mm such that said optical probe can access a biliary or pancreatic system using a working channel of an endoscope inserted orally. 
     Other aspects and advantages of the invention will be apparent from the following description and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  illustrates schematically an oral insertion of an endoscope in a duodenum according to an embodiment of the present invention. 
         FIG. 2  illustrates an introduction of a catheter in a major duodenal papilla according to an embodiment of the present invention. 
         FIG. 3  illustrates an ERCP procedure according to the prior art. 
         FIG. 4  are simultaneous radiographic and endoscopic representations resulting from an ERCP procedure according to the prior art. 
         FIG. 5  are radiographic images of healthy and unhealthy bile ducts resulting from an ERCP procedure according to the prior art. 
         FIG. 6  illustrates several parts of a distal part of an optical probe according to an embodiment of the present invention. 
         FIG. 7  illustrates several parts of a distal part of an optical probe according to an embodiment of the present invention. 
         FIG. 8  illustrates several parts of a distal part of an optical probe according to an embodiment of the present invention. 
         FIG. 9  illustrates several parts of a distal part of an optical probe according to an embodiment of the present invention. 
         FIG. 10  illustrates an introduction of a per-oral cholangioscope in a duodenoscope and of an optical probe into the cholangioscope. 
         FIG. 11  are cholangioscopical images of a patient with a partial biliary obstruction. 
         FIG. 12  are cholangioscopical images of a patient with a complete biliary obstruction. 
         FIG. 13  are confocal images of benign strictures of a patient obtained using a confocal fiber microscope according to an embodiment of the present invention. 
         FIG. 14  are confocal images of malign strictures of a patient obtained using a confocal fiber microscope according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION  
     Specific embodiments of the present invention will now be described in detail with reference to the accompanying Figures. Like elements in the various Figures may be denoted by like numerals. 
     Embodiments of the invention relate to methods and devices capable of obtaining microscopic images of a mucosa in a biliary/pancreatic system. Embodiments of the invention can improve the quality of diagnosis of pancreatic or biliary cancers. Embodiments of the disclosure also relate to a method for tissue sampling, which takes advantage of microscopy to accurately target a tissue to be sampled. 
       FIG. 1  shows an anatomical illustration of an oral endoscopy with a catheter introduction in a major duodenal papilla of a patient. Such oral endoscopy may be used with embodiments of the present invention. As shown in  FIG. 1 , an endoscope  160  is orally inserted. The endoscope  160  is gradually advanced down the esophagus and passed through the stomach  100  to reach the duodenum  110 . The endoscope  160  may be a duodenoscope, comprising a lateral opening for accessing the major duodenal papilla.  FIG. 1  farther illustrates the introduction of a catheter  161  in the papilla at a union between the common bile duct  130  and the pancreatic duct  140 . Also shown in  FIG. 1  are a gallbladder  120 , a cystic duct  121 , a common hepatic duct  122 , which arises from right and left main hepatic ducts and joins the cystic duct at the level of a junction  123 , and a pancreas  150 , from which arise the pancreatic duct  140 . 
     In accordance with some embodiments of the present invention, the endoscope  160  may be a duodenoscope. In accordance with other embodiments of the present invention, the endoscope  160  may be a cholangioscope accessing directly the biliary/pancreatic systems. With such a cholangioscope, catheter introduction may not be performed because the cholangioscope may access directly the union between the common bile duct  130  and the pancreatic duct  140 . In accordance with such embodiments, a fiber microscope may access the biliary/pancreatic systems through a working channel of a cholangioscope. 
       FIG. 2  shows an expanded representation of a catheter introduction, from an endoscope  160  placed in the duodenum  110 , into the union of the common bile duct  130  and the pancreatic duct  140 . This union is commonly referred to as the Ampulla of Vater  210  and enters the duodenum  110  at the major duodenal papilla  200 . In accordance with one embodiment of the present invention, a fiber microscope is inserted in the lumen of the catheter and is then enabled to access a mucosa of the biliary or pancreatic system. The use of a fiber confocal microscope may enable non-superficial microscopic imaging of untreated tissue without previous fixation and preparation of slices. In accordance with another embodiment of the present invention, a per-oral cholangioscope is inserted in a working channel of the endoscope  160  and is further introduced into the union of the common bile duct  130  and the pancreatic duct  140 . Per-oral cholangioscope refers to an endoscope accessing the biliary/pancreatic system using a working channel of another endoscope. In accordance with such an embodiment, a fiber microscope may access the biliary/pancreatic system through a working channel of the per-oral cholangioscope. 
     Introducing a catheter in the major duodenal papilla is also commonly used in the prior art, for example, in an ERCP procedure. Two arrows on  FIG. 2  illustrate a possible injection of dye into the pancreatic/bile ducts, which may be operated according to a classic ERCP procedure. The contrast agent may be, for example, an X-ray contrast agent. This injection may be used for further performing X-ray acquisition with a fluoroscope. The introduction of a catheter into the union of the common bile duct and the pancreatic duct is increasingly performed for therapeutic purposes, such as tissue sampling, while ERCP procedures for pure diagnosis purpose are performed at decreasing frequencies. 
     The biliary system may commonly refer to the Vater Ampulla  210 , the common bile duct  130 , the right and left main hepatic ducts, the common hepatic duct  122 , the cystic duct  121 , and the gallbladder  120 . The pancreatic system may commonly refer to the pancreatic duct  140  and the pancreas  150 . 
       FIG. 3  illustrates several elements coordinated in order to implement an ERCP procedure according to the prior art. The ERCP procedure takes place in a special ERCP suite that has an instant X-ray machine, called a fluoroscope  310 . Patient is under conscious heavy sedation. Duration is approximately 30 to 90 minutes. A basic ERCP procedure consists generally of using an endoscope  160  inserted orally into the duodenum and placing a catheter  161  in the bile/pancreatic duct for injection of a radiographic contrast to provide X-Ray images of the ducts. Injection shows indirect effects of bile/pancreatic cancer or stones, such as blockage or dilatation of ducts and inflammation of tissue. An advanced ERCP procedure may further comprise papillotomy and insertion of a special device for cholangioscopy, pancreaticography, stone retrieval, sphincterotomy, drainage, stenting, cytology, or biopsy. 
     Although ERCP is an invasive procedure with attendant risks, it enables one to obtain biopsies and to place stents or to perform other interventions to relieve biliary/pancreatic obstructions. Endoscopic ultrasound may also be performed at the time of ERCP and may increase the accuracy of the tissue sampling and yield information on lymph node invasion and operability. 
     Referring still to  FIG. 3 , a doctor  300  inserts orally a endoscope  160  into a patient. A catheter  161  is introduced into a working channel of the endoscope  160  and steered into the pancreatic/bile ducts using an endoscopic display on an endoscope monitor  330 . Injection of an X-ray contrast agent in the bile/pancreatic ducts is carried out and X-ray images from the fluoroscope  310  may be displayed on an X-ray monitor  320 . Displays may also be stored on a computer  340 . 
     Images  400  and  410  in  FIG. 4  are, respectively, radiographic and endoscopic images, which may be obtained through a prior art ERCP procedure, described above with reference to  FIG. 3 . An endoscope  160  and a common bile duct  130  are visible in image  400 . 
     Images  500  and  510  in  FIG. 5  are, respectively, radiographic images of healthy and unhealthy bile ducts, which may be obtained through a prior art ERCP procedure, described above with reference to  FIG. 3 . Biliary ducts and main pancreatic duct  140  observed in image  500  are narrow and a gall bladder  120  is visible without any stones. It is possible to observe stones in the common biliary duct in image  510 . 
       FIG. 6  illustrates several parts of an optical probe distal tip according to an embodiment of the present invention. The optical probe comprises a coherent bundle  610  of several thousands of optical fibers sheathed in a sheath  600 . The fibers may, for example, have a core diameter of 2 μm and a mean core spacing of 3.3 μm. A proximal end of the bundle may be connected to a real-time scanning confocal microscope (such as Cellvizio® from Mauna Kea Technologies), and a distal end of the bundle may be equipped with a miniaturized objective. A proximal end may also be connected to any type of fiber microscopes. Confocal capabilities may enable microscopic imaging of upper layers of the epithelium of pancreatic and bile ducts even through bile. Observations at cellular or micro-vascular levels with high sensitivity may also be made possible. The proximal confocal microscope may include an illumination source, which may be a LASER source, capable of exciting endogenous or exogenous fluorophores fluorescence. The proximal confocal microscope may also include a detection channel, which permits collecting and measuring a fluorescence signal. In an embodiment, the confocal microscope is a reflection microscope collecting and measuring backscattered light. The distal objective conjugates the distal end of the fiber bundle with a specific image plane, at a specific working distance when the probe is in contact with a biological tissue. 
     When illuminated one after another by the proximal scanner, each fiber of the bundle becomes an illumination source of a small volume within the tissue. This illumination may excite endogenous or heterogeneous fluorescence. In addition to functioning as a source of light, the illumination fiber also collects the fluorescence signal and transmit it to the proximal scanner. There, the return beam is spatially filtered and directed to the detection channel. As a result, the probe and its proximal scanner perform a confocal exploration of the tissue. 
     Referring to  FIG. 6 , a miniaturized objective  630  at a distal end of the bundle  610  may consist of individual standard lenses, or GRIN lenses, or a combination of both. 
     This allows adapting the output beam to the application, and thus providing the probe with a resolution, a working distance, a depth of focus that complies with an optical analysis of the tissue and its architecture. A mechanical mount  640  may protect a junction between the optics  630  and the distal tip of the bundle  610 , said mechanical mount  640  may also limit the bundle distal end invasiveness. A metallic ferrule  620  may cover the junction between the sheath and the mechanical mount  640 . The metallic ferrule  620  may hinder the sheath from shifting or taking off because of constraints applied to the bundle distal end, for example during endoscope insertion or cleaning procedures. 
       FIG. 7  illustrates a design of an optical probe distal tip according to an embodiment of the present invention. An optical fiber bundle  710  is partially covered (sheathed) in a sheath  700 , the distal tip of the optical fiber bundle  710  being not covered by the sheath  700 . The external diameter of the sheathed bundle is referred to as Hg in  FIGS. 7-9 . A miniaturized objective  730  is placed at the distal tip of the optical fiber bundle  710 , coaxially with said optical fiber bundle  710 . The miniaturized objective  730  may be cylindrical and of a diameter equal to a diameter of the fiber bundle distal tip. A mechanical mount  740  assembles the distal tip of the optical fiber bundle  710  and the miniaturized objective  730 , covering the junction of the optical fiber bundle  710  and the miniaturized objective  730 . The mechanical mount  740  has a tubular shape, and the distal tip of the optical fiber bundle  710  and the miniaturized objective  730  fit inside the lumen of the mechanical mount  740 . The external diameter of the mechanical mount  740  is equal to Hg. A ferrule  720 , which may be metallic, assembles the sheath  700  and the mechanical mount  740 , covering a portion of the sheath  700  and the mechanical mount  740  over a possible junction. An external diameter of the ferrule  720  is referred to as Ht in  FIGS. 7-9 . Because of the mechanical mount  740  and/or the ferrule  720 , the distal tip of the optical probe thereby presents a rigid part. A length of this rigid part at the optical probe distal tip is referred to as L in  FIGS. 7-9 . 
     For accessing the biliary/pancreatic systems, optical fiber probes have to respect severe size requirements as the diameter of common cholangioscopes working channels may be less than 1.2 mm. Miniaturization comes with loss of robustness, resulting from a decrease in contact surfaces between different parts of the distal tip. Despite a very high level of miniaturization, attention may be paid to robustness of the distal tip. Particularly, contact surfaces between the sheath and the ferrule may be kept maximal, in order to provide resistance to traction and to repetitive cleaning and disinfection procedures. For example, the distal end of the fiber bundle may withstand up to twenty manual disinfections and thirty insertions/extractions in endoscopes. In accordance with some embodiments of the invention, the distal end of an optical fiber bundle may also be of single use. In accordance with some embodiments of the invention, the distal end of an optical fiber bundle may be used up to ten times. 
     On the other hand, in order to keep the steering capabilities of the endoscopes to access bile ducts, and notably because of tip deflections of such endoscopes, optical probe rigid part size may be limited. Common characteristics for optical probes presented in  FIGS. 7-9  may be, for example: Depth of observation about 40 to 50 μm, Field of view about 325 μm, lateral resolution about 3.5 μm, axial resolution about 40 μm, rigid part length L from about 4 mm to about 5.6 mm, external diameter Ht from about 0.85 mm to about 1.15 mm. Such miniaturization level enables the tip of the optical probe to be placed in a perpendicular angle to the tissue, or at least tangential rather than in a longitudinal manner in the biliary/pancreatic ducts. 
       FIG. 8  illustrates a design of an optical probe distal tip according to another embodiment of the present invention. This design comprises five elements: an optical fiber bundle  810 , a miniaturized objective  830 , a non invasive mechanical mount  840  having a non traumatic form, a ferrule  820  and a sheath  800 . The optical fiber bundle  810  is sheathed in the sheath  800 , the distal tip of the optical fiber bundle being not covered by said sheath. The miniaturized objective  830  is placed coaxially at the distal tip of the optical fiber bundle  810 . The mechanical mount  840  assembles the distal tip of the optical fiber bundle  810  and the miniaturized objective  830 , covering a possible junction between these two elements. The mechanical mount  840  extends to the tip of the miniaturized objective  830  that is to be in contact with an observed tissue. At the tip of the miniaturized objective  830 , the mechanical mount  840  may have a round (smooth) edge in order to limit its invasiveness, the maximal external size of the mechanical mount being less than or equal to an external diameter of the ferrule  820 . The optical fiber bundle  810  and the miniaturized objective  830  may be glued using a glue (e.g., Vitralit ®) using a tool to ensure coaxiality. The mechanical mount  840  may be then glued to the junction between the miniaturized objective  830  and the optical fiber bundle  810  with a glue (e.g., Epotek 301 ®). The ferrule  820 , which may be metallic, may be glued on the sheath  800  and the mechanical mount  840  using a glue (e.g., Epotek 301 ®). The length of the rigid part for this design may be, for example, about 5 mm and the external diameter may be of about 0.94 mm. 
       FIG. 9  illustrates a design of an optical probe distal tip according to another embodiment of the present invention. This design comprises four elements: an optical fiber bundle  910 , a miniaturized objective  930 , a non invasive mechanical mount  940  having a non traumatic form and a sheath  900 . The miniaturized objective  930  is placed coaxially at the distal tip of the fiber bundle  910 . The mechanical mount  940  assembles the distal tip of the bundle  910  and the miniaturized objective  930 , covering a possible junction between these two elements and extending to the tip of the miniaturized objective  930  that is to be in contact with an observed tissue. At the tip of the miniaturized objective  930  to be in contact with the observed tissue, the mechanical mount  940  may have a round (smooth) edge in order to limit its invasiveness. The sheath  900  wrapping the fiber bundle  910  may also cover partially the mechanical mount  940 . At the tip of the miniaturized objective  930 , the maximal external size of the mechanical mount  940  may be less than or equal to the external diameter of the sheath  900 . 
     A method for manufacturing this design may be to first pull out the sheath in order to strip a bundle distal part, to which is attached a miniaturized objective. The mechanical mount may be then glued to the junction between the bundle distal part and the objective and the sheath may be then pushed to cover the mechanical mount. The bundle and the miniaturized objective may be glued using a glue (e.g., Vitralit ®) using a tool to ensure coaxiality. The mechanical mount may be then glued to the junction between the miniaturized objective and the bundle with a glue (e.g., Epotek 301 ®). Length of the rigid part for this design may be about 4 nm and the external diameter may be of about 0.85 mm. 
     Image  1000  in  FIG. 10  illustrates an introduction of a per-oral cholangioscope in a working channel of a duodenoscope. Image  1100  highlights steering capabilities of a deflection tip of the cholangioscope. Image  1200  illustrates an introduction of an optical probe according to embodiments of the present invention in a working channel of a cholangioscope. Image  1300  illustrates steering of the optical probe loaded into the cholangioscope. 
       FIG. 11  show cholangioscopical images of a patient with a partial biliary obstruction. The image on the left is an endoscopic image, arrows indicate a small polypoid mass. After endoscopic detection of an area of interest, an optical probe according to embodiments of the present invention may be positioned in said area. On the right image, a star indicates a miniaturized objective according to embodiments of the present invention, positioned on the polypoid mass. 
       FIG. 12  are cholangioscopical images of a patient with a complete biliary obstruction. The image on the left is an endoscopic image, arrows are indicating a important polypoid tumor obstructing a bile duct. After endoscopic detection of an area of interest, an optical probe according to embodiments of the present invention may be positioned in said area. On the right image, a star indicates the miniaturized objective according to embodiments of the present invention, positioned on the tumor. 
       FIG. 13  are confocal images of benign strictures of a patient. The images are obtained using a confocal fiber microscope according to an embodiment of the present invention. Benign findings are characterized by reticular arrangement of dark-grey bands on a light-grey background. 
       FIG. 14  are confocal images of malignant strictures of a patient. The images are obtained using a confocal fiber microscope according to an embodiment of the present invention. Malign findings are characterized by a black/dark-grey background with irregular large white streaks representing blood vessels filled with fluorescein. 
     Advantages of embodiments of the invention may include one or more of the following. Embodiments of the invention are compatible with existing fiber-based confocal microscopes, such as Cellvizio® from Mauna Kea Technologies (Paris, France). Miniprobes and methods of the invention can be seamlessly integrated into the workflow of other Glendoscopic procedures. In addition, the new ERCP procedures can also be integrated with existing protocols. The working distances of embodiments of the invention, for example—50 μm—and their confocal capabilities permit microscopic imaging of the upper layers of the epithelium of the pancreatic duct or the bile duct even through the bile. At this depth, observations at cellular or micro-vascular levels with a high sensitivity is made possible. Thanks to their high level of miniaturization, the miniprobes of the invention are fully compatible with the existing procedures, and the miniprobes dimensions are compatibles with cholangioscopes&#39; working channel and/or existing catheter. Miniprobes of the invention are robust; they can withstand at least 20 manual disinfections (standard chemical products) and 30 insertions/extractions in the endoscopes. 
     While embodiments of the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments may be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.