System and method for guided biliary cannulation

Abstract

A cannulator for a biliary cannulation includes a cannula configured to enter a duct of a biliary tree, a depth sensor arranged in a fixed orientation with the cannula, an output interface configured to output data indicating that the depth of the tissues with respect to the orientation of the cannula is within the range, and an actuator configured to change the orientation of the cannula toward the tissues with depth within the range to enter the duct The depth sensor is configured to emit a signal penetrating tissues over a distance sufficient to detect the orientation of the cannula when the depth of the tissues in a neighborhood of the duct with respect to the orientation of the cannula is within a range.

Description

[0001] SYSTEM AND METHOD FOR GUIDED BILIARY CANNULATION

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This patent application claims the benefit of US provisional patent application 63 / 756,297, filed on February 10, 2025, which is incorporated herein by reference in its entirety.

[0004] FIELD OF THE INVENTION

[0005] This invention relates generally to biliary cannulation and more particularly to a cannulator such as a sphincterotome adapted for guided biliary cannulation during endoscopic procedures such as endoscopic retrograde cholangiopancreatography (ERCP).

[0006] BACKGROUND ERCP is a study of the ducts that drain the liver and pancreas. Generally, the liver produces bile that is concentrated by the gallbladder and delivered to the duodenum (upper small intestine) via the common bile duct. The pancreatic duct joins the bile duct at the papilla of Vater where they drain into the duodenum through the sphincter of Oddi. ERCP generally includes cannulation of the biliary tree (which includes one or combination of the bile duct, pancreatic duct, and hepatic ducts of the liver) by delivering a cannula through the working channel of a duodenoscope and into the biliary tree. A contrast medium is injected through the cannula to provide for diagnosis of problems in the liver, gallbladder, biliary tree and pancreas, such as gallstones, inflammatory strictures, leaks or cancer. As used herein, a cannulator is an endoscopic access device such as sphincterotome, catheter, balloons, biopsy devices, stent delivery catheters, dilators, etc. Exemplary ERCP cannulators are described in U.S. Pat. 5,320,602 and 5,383,849, the teachings of which are incorporated herein by reference.

[0007] A wire guide is often used to assist in navigation of the cannulator through the sphincter of Oddi and into the biliary tree. Such a procedure is referred herein as cannulation. Wire guides may also be used for deep cannulation of the biliary tree. Wire guides, however, carry the risk of trauma to structured segments of the bile or pancreatic ducts which can result in life-threatening infection, perforation or pancreatitis. The wire guided cannulation is intrusive, may damage the tissues along its propagation path and provide rudimental “blind” navigation that can lead tocomplications due to unintended insertion of guide wire and / or injection of contrast media to the main pancreatic duct, guidewire navigation relies on tactile (non-visual) feelings, i.e., blind, while the locations of the ducts with respect to placement of the cannula placed during the first stage vary for different patients and / or for different procedures. Accordingly, a user of the cannulator needs to extend the wire in different directions to manually feel the resistance of the tissues to find an opening to the ducts with less of the resistance. Such a blind navigation is problematic in itself. Moreover, such an opening is not guaranteed to be a target duct, e.g., a bile duct targeted by ERCP. In some situations the cannula can be placed within a pancreatic duct, which is undesirable for some medical operations.

[0008] Accordingly, there exists a need for a guided biliary cannulation of the bile, pancreatic or hepatic ducts that reduces the potential for trauma to the ducts. At the same time, it would also be desirable to visualize navigation of the cannulators through the dark areas of biliary cannulation.

[0009] SUMMARY

[0010] According to embodiments, a cannulator for a biliary cannulation comprises: (a) a cannula; (b) a depth sensor coupled to the cannula at a fixed orientation thereto and configured to emit a tissue-penetrating signal in response to a user input, the depth sensor characterized by one or more power ratings and one or more operating frequencies effective to determine, for a given in-situ environment, a signalpenetration range of the depth sensor; (c) an actuator arranged to change an orientation of the cannula and of the depth sensor coupled thereto, the coupling being such that a change in an orientation of the cannula changes an orientation of the depth sensor; and (d) a control system comprising an output interface configured to provide information about tissues detected by the depth sensor. The tissue-penetrating signal is effective to measure a depth of a tissue relative to the depth sensor when deployed in the given in-situ environment.

[0011] In some embodiments, a method of performing a biliary cannulation comprises: (a) providing the cannulator according to any of the embodiments disclosed herein; of any one of the preceding claims; (b) placing the cannula in a duodenum in proximity to a target duct; (c) emitting the tissue-penetrating in proximity to the target duct; and (d) in response to data received from the depth sensor, employing the actuator to change the orientation of the cannula.

[0012] BRIEF DESCRIPTION OF THE DRAWINGSThe invention will now be described further, by way of example, with reference to the accompanying drawings, in which the dimensions of components and features shown in the figures are chosen for convenience and clarity of presentation and not necessarily to scale. In the drawings:

[0013] Figure 1A shows an example of a cannulator according to embodiments of the present invention.

[0014] Figure IB shows a zoom-in schematic of an end portion of the sphincterotome according to embodiments of the present invention.

[0015] Figures 2A and 2B show schematics of multi-stage biliary cannulation procedure according to embodiments of the present invention.

[0016] Figure 3 shows a schematic of time-of-flight principles employed by some embodiment for guided cannulation according to embodiments of the present invention.

[0017] Figure 4 shows a schematic of principles of bounded and / or binary depth sensing according to embodiments of the present invention.

[0018] Figure 5A shows a schematic of a method for a guided navigation of a cannulator according to embodiments of the present invention.

[0019] Figure 5B shows a schematic of a differentiating procedure performed for a guided biliary cannulation of a cannulator according to embodiments of the present invention.

[0020] Figure 6A shows a block diagram of a piezoelectric transducer according to embodiments of the present invention.

[0021] Figure 6B shows a comparative illustration of dimensions of the transducer of Figure 6A according to embodiments of the present invention.

[0022] Figure 7A shows an exemplar schematic of arrangement of a single ultrasonic transducer on a cannula according to embodiments of the present invention.

[0023] Figure 7B shows an exemplar embodiment of the depth sensor including multiple ultrasonic transducers according to embodiments of the present invention.

[0024] Figure 7C shows a cross-section of a cannula having a depth sensor including multiple ultrasonic transducers according to embodiments of the present invention.

[0025] Figure 8 shows a block diagram of a guided biliary cannulation according to embodiments of the present invention.

[0026] DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTSThe invention is herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. Throughout the drawings, like-referenced characters are generally used to designate like elements.

[0027] Embodiments of the invention relate to systems and methods for biliary cannulation during endoscopic procedures such as, for example, such as an endoscopic retrograde cholangiopancreatography (ERCP). The embodiments include providing and / or using a cannulator, such as a sphincterotome, adapted for guided biliary cannulation. In embodiments, visualization techniques are disclosed that can assist in guiding the cannulator during the biliary cannulation in an unobtrusive manner that reduces the risk of trauma to the ducts of a patient, some embodiments, such a visualization technique can allow performing biliary cannulation in an automatic manner reducing the risk of human error during the selective duct cannulation.

[0028] Biliary cannulation procedures can include several distinct stages. During the first stage, a cannula of a cannulator, such as a tip of the sphincterotome, is placed within the tissues in proximity to the duct. For example, for a bile duct cannulation, a tip of a sphincterotome is placed in a duodenum near the sphincter of Oddi guarding an entrance to the bile duct. During the next stage, the cannula is navigated through the tissues toward, hopefully, the entrance of the duct. After the cannula enters the duct, the desired operation of the cannulation is performed.

[0029] The placement of the cannula of the cannulator within the tissues during the first stage of biliary cannulation can be performed using a number of different visualization techniques, such an ultrasound originated outside of a body of a patient or a camera placed inside of the patient’s body. However, the second stage of propagating cannula through the tissues is known to be performed ‘blind’, i.e., without visualization, and therefore is potentially dangerous. This is becauseguidewire navigation relies on tactile feedback without visual input, while the locations of the ducts with respect to placement of the cannula placed during the first stage vary for different patients and / or for different procedures. Accordingly, a user of the cannulator needs to extend the wire in different directions to manually feel the resistance of the tissues to find an opening to the ducts with less of the resistance. Such a blind navigation is problematic in itself. Moreover, a selected opening is not guaranteed to be the target duct, e.g., a bile duct targeted by ERCP. In some situations, the cannula can be placed, inadvertently, within a pancreatic duct, which is undesirable for some medical operations.

[0030] The reason for relying on blind navigation can be twofold. First, medical imaging originated outside of the patient body does not have the required resolution to navigate the cannulator to miniature ducts without having a common point of reference between the outside medical imaging and the cannula. Second, the navigation through the tissues precludes usage of video sensors and other optical cameras.

[0031] According to embodiments, the placement of the cannula within the tissues during the first stage of cannulation, which causes the problem of the guided cannulation, can be turned into an advantage and used for see-through-tissue navigation. Specifically, techniques used for estimation of distance to an object in a scene can be used for depth estimation of an object after the sensor is placed within the object. This is because an object reflects an incident signal at an interface of a change in medium. Typically, such a medium change is from a sparse medium to a dense medium. However, such a relationship can be reversed. As such, when a signal is originated outside of the object, such as in radar systems, the signal emitted by the radar is reflected at an external border between the object and the volume outside the object. However, when a signal is originated inside the object, the signal is reflected at the border between the object and the volume inside of the object. Hence, sensor placed outside of the object is a distance sensor to measure a distance to the object using time-of-flight principles, while a sensor placed inside an object is a depth sensor to measure depth of the object using the time-of-flight principles modified for signal propagation in a dense medium within the object.

[0032] In this disclosure, the object comprises the tissues in a neighborhood of a duct of an interest, and because the cannulator is placed within the tissues during the first stage of cannulation, a depth sensor can be used for visual navigation. Moreover, thedepth sensor can be arranged in a fixed orientation with the cannula, such that a change in an orientation of the cannula changes an orientation of the depth sensor. For example, the depth sensor can be rigidly attached to the cannula. In such a manner, the depth sensor has a common frame of reference with cannula, and the change of the orientation of cannula dictates what the depth sensor can sense.

[0033] The depth sensor is configured to emit a signal penetrating tissues over a distance sufficient to detect the orientation of the cannula when the depth of the tissues in a neighborhood of the duct is within a range, e.g., less than a threshold with respect to the orientation of the cannula. Because a duct carries liquid, which is a medium with different density from the density of the tissues, the signal is reflected at the border of the duct indicting the reduced depth of the surrounding tissues. Due to the fixed mutual orientation, the cannula can be guided toward the tissues having depth within the range to enter the duct. For example, the orientation of the cannula can be changed to reduce an error of the orientation of the cannula with respect to locations of the tissues with depth within the range and to point the cannula toward the locations of the tissues with depth within the range to enter the duct.

[0034] Additionally or alternatively, in contrast with distance sensors that may or may not sense an object in the scene, a depth sensor can be configured to always detect a border of the object due to the definiteness of the object’s shape. However, for guided cannulation, the total shape of the tissues surrounding the duct may be less important and may complicate the navigation. To that end, some embodiments use a bounded depth sensor to measure the depth of the tissues less than a value of the range. The range is determined based on specifics of the cannulation procedure. For example for bile duct cannulation the range is 5 cm, because the bile duct is typically located with 5 cm from initial placement of the sphincterotome during the first stage. This bounding allows distinguishing a duct of an interest from other bodily structures.

[0035] Additionally or alternatively, in some embodiments the depth sensor is configured or programmed to provide a binary response in terms of whether the depth of the tissues with respect to orientation of the cannula is above the range or within the range. Based on the anatomical structure of a patient, i.e., in the area near the entrance to the ducts, the depth of the tissues is within the range, and such a reduction of the depth is due to the ducts and not something else. The distance to the ducts can thus be ignored and the binary depth sensor can be used to indicate only the directiontoward the entrance to the ducts. These bounded and / or binary measurements simplify the guided cannulation and reduce the cost of manufacturing the guided cannulator.

[0036] In such a manner, the bounded depth sensing within a range adjusted for specifics of a medical procedure transforms a depth sensor into a navigation device for biliary cannulation. Different techniques are disclosed for imposing bounds on the depth sensing. For example, one technique uses a filter configured to limit maximum depth measured by the depth sensor based on a value of the range. For example, a filter can be a high frequency band filter. This embodiment can adapt a depth sensor to different medical procedure by adjusting a filter. For example, one technique uses a depth sensor that emits signal in a millimeter wave spectrum. The distance of millimeter wave propagation may be beyond what is necessary to detect a bile duct, but reflection of the millimeter wave can help to understand the initial placement of the cannula at the end of the first stage of biliary cannulation with respect to bodily organs. After such an initialization, the filter can limit echoes of an emitted signal only to reflections from medium interfaces within a predetermined range.

[0037] Additionally or alternatively, some techniques select or configure the depth sensors to emit signals that propagate through tissues over a double distance of the range of interest to detect reflection of the signals only when the depth of the tissues is within the range. For example, in one technique, the cannulator is a sphincterotome for bile duct cannulation. The range of a search for a bile duct from initial placement of the sphincterotome is typically less than 5 cm. The technique therefore uses a depth sensor that emits ultrasound signal able to penetrate the tissues and return back from the border between the tissues if located within 5 cm from the depth sensor, but would fade within the tissues if such a border is not detected.

[0038] In some embodiments, the depth sensor includes an ultrasonic transducer that emits an ultrasound signal. The ultrasonic transducer is configured to transform an input electrical signal into the ultrasound and to convert an echo of the transmitted ultrasound into an output electrical signal. The amplitude of the output electrical signal indicates the depth of the tissues, such that when amplitude of the output electrical signal is above a threshold, the depth of the tissues is within the range. In some implementations, the ultrasonic transducer is configured to emit the ultrasound having a frequency between 1.5 MHz to 3 MHz, such that the depth sensor is bounded to measure the depth of the tissues less than 5cm.In embodiments, ultrasonic transducers can be advantageous for guided biliary cannulation due their small size and ability to provide bounded depth sensing. As used herein, ultrasonic transducers or ultrasonic sensors are a type of acoustic sensor divided into three broad categories: transmitters, receivers and transceivers.

[0039] Transmitters convert electrical signals into ultrasound, receivers convert ultrasound into electrical signals, and transceivers can both transmit and receive ultrasound. Different embodiments use different number and / or type of ultrasonic transducers. In embodiments using a single ultrasonic transducer, the transducer includes a transceiver. In embodiments using multiple ultrasonic transducers, the type of ultrasonic transducers can vary.

[0040] In some embodiments, a depth sensor can include a set of ultrasonic transducers attached to the cannula according to a predetermined pattern to form a synthetic aperture of the depth sensor oriented toward a direction of motion of the cannula. These embodiments can increase an area observed by the depth sensor without increasing the size of the transducers. In some embodiments, each ultrasonic transducer includes an ultrasonic transmitter and an ultrasonic receiver. This embodiment simplifies implementation and maintenance of the depth sensor. In some embodiments, the set of ultrasonic transducers includes one ultrasonic transmitter and multiple ultrasonic receivers; this arrangement can reduce the cost and dimensions of components of the depth sensor.

[0041] Different types of actuators can be used for navigating a cannula to enter a bodily duct. In one non-limiting example, the cannulator is a sphincterotome, and the actuator of the sphincterotome includes a flexible tube attached to the cannula such that the cannula forms a tip of the sphincterotome, and a wire extending at least in part within the tube and rigidly attached to the cannula such that a change of tension of the wire beds the flexible tube and causes a change of the orientation of the cannula. In such a manner, the cannula can be guided by changing the tension of the wire.

[0042] In one non-limiting example, the cannulator is operated by a user, e.g., a medical professional performing ERCP. In such a example, the cannulator can include a handle assembly allowing a user of the sphincterotome to change the tension of the wire.

[0043] In embodiments, the depth sensor of the cannulator can include an output interface operatively connected to a display device to display locations of the tissues having depth within the range. The locations are rendered on the displaydevice with respect to the orientation of the cannula, such that that the change in the orientation of the cannula changes rendering of the locations. By observing the displayed relative locations, the user can estimate an error of the orientation of the cannula with respect to locations of the tissues with depth within the range and manipulate the actuator to change the orientation of the cannula to reduce the error and to point the cannula toward the locations of the tissues with respective depths within the range.

[0044] Additionally or alternatively, data from the depth sensor can be used to navigate the cannula automatically or at least semi-automatically under the supervision of a medical professional. A system for guided biliary cannulation can include a controller having a processor configured to change the tension of the wire based on data from the depth sensor. In some implementations, the processor is configured to execute a neural network trained to transform the data from the depth sensor into values of the tension of the wire, such that the processor changes the tension of the wire according to the values determined by the neural network.

[0045] In some embodiments, a cannulator for a biliary cannulation can include a cannula configured to enter a duct of a biliary tree, a depth sensor arranged in a fixed orientation with the cannula, such that a change in an orientation of the cannula changes an orientation of the depth sensor, wherein the depth sensor is configured to emit a signal penetrating tissues over a distance sufficient to detect the orientation of the cannula when the depth of the tissues in a neighborhood of the duct with respect to the orientation of the cannula is within a range; an output interface configured to output data indicating that the depth of the tissues with respect to the orientation of the cannula is within the range; and an actuator configured to change the orientation of the cannula toward the tissues with depth within the range to enter the duct.

[0046] Another embodiment discloses a sphincterotome having an ultrasonic transducer attached to its tip.

[0047] We now refer to the figures, and in particular to Fig. 1A, which schematically illustrates an exemplary cannulator comprising a sphincterotome 100 and a depth sensor attached at or adjacent to the tip of the sphincterotome 100.

[0048] Figure 1A shows an example of a cannulator according to one embodiment. A ‘cannulator’, as the term is used herein, is a device used in cannulation, e.g., a device that aids cannulation. In the non-limiting example of Fig. 1A, the cannulator comprises a sphincterotome 100. Different types of sphincterotomes and / or otherendoscopic devices may be used as cannulators. Exemplary implementations may use a catheter, a balloon, a biopsy device, a stent delivery catheter, or a dilator. The sphincterotome 100 of Fig. 1 A includes a cannula 112 configured to enter a duct of a biliary tree and an actuator configured to change the orientation of the cannula in order to enter the duct. In this example, the actuator includes a flexible tube 102 attached to the cannula such that the cannula 112 forms a tip of the sphincterotome and a wire 108 extending at least in part within the tube and rigidly attached to the cannula such that a change of tension of the wire causes a change of the orientation of the cannula.

[0049] In the example of Fig. 1A, the sphincterotome 100 includes a polymer tubular shaft 102 made of PTFE (polytetrafluoroethylene) or another flexible material. An electroconductive filament 104, also called a drive wire, is disposed in a lumen 106 running through the shaft 102. The distal end of the filament 104 is connected or anchored to the distal end of the shaft 102. A short segment of the electroconductive filament 104 near the distal end is disposed outside of the shaft 102 for use as an electrocautery cutting wire 108. The proximal end of the filament 104 is connected to the proximal handle assembly 110 such that actuation of the handle assembly 110 partially retracts (i.e., pulls in a proximal direction) the filament 104 relative to the polymer shaft 102. This actuation results in the distal end of the shaft 102 bowing the cannula 112 to form an arc, with the exposed filament forming a secant of the arc 112 so as to form a cutting wire 108. Electric current passed through the filament 104 from an electrode 114 in the handle assembly 110 enables the cutting wire 108 to act as an electrosurgical cutting element that may be used effectively to cut and cauterize tissue, such as the sphincter of Oddi in the exemplary procedures described above.

[0050] The sphincterotome 100 includes a depth sensor 120 arranged in a fixed orientation with the cannula 112, such that a change in an orientation of the cannula 112 changes an orientation of the depth sensor 120. In embodiments, the depth sensor 120 can be rigidly attached to the cannula 112. The depth sensor 120 is configured to emit a signal penetrating tissues over a distance sufficient to detect the orientation of the cannula 112 when the depth of the tissues in a neighborhood of the duct with respect to the orientation of the cannula is within a range of suitable depths. The depth sensor 120 outputs data 125 indicating that the depth of the tissues with respect to the orientation of the cannula is within the range. The data 125 can be rendered on a display device 130 for guided biliary cannulation.Figure IB shows a zoom-in schematic of an end portion of an exemplary sphincterotome 100 according to embodiments. This figure further illustrates an exemplar flexible tube 140 attached to the cannula 150 such that the cannula forms a tip of the sphincterotome 100 and a wire 145 extending at least in part within the tube and rigidly attached to the cannula such that a change of tension of the wire causes a change of the orientation of the cannula. Specifically, the tension of the wire governs the bending of the tube 140 that changes orientation of the cannula 150.

[0051] The depth sensor 120 is coupled to the cannula 150 near the tip of the sphincterotome 100. In one implementation, the depth sensor 120 is rigidly attached to the cannula 150, e.g., using adhesive materials such as silicon. In an alternative design, the depth sensor can slide along the length of the cannula in the grooves that prevents changes of mutual orientation of the depth sensor with respect to orientation of the cannula to preserve their fixed orientation arrangement.

[0052] Figures 2A and 2B show schematics of a multi-stage biliary cannulation procedure according to some embodiments. Specifically, the biliary cannulation includes several distinctive stages. During the first stage 215, a cannula 265 of a cannulator, such as a tip of the sphincterotome, is placed 210 within the tissues in proximity to the duct. For example, for a bile duct cannulation, a tip of a sphincterotome is placed in a duodenum 250 near an entrance to the bile duct, such as a bile duct 230 and / or a pancreatic duct 240. During the next stage 225, the cannula is navigated 220 through the tissues 250 toward, the targeted area, i.e., the entrance of the duct. After the cannula enters the duct of an interest, the desired operation of the cannulation is performed.

[0053] The placement of the cannula 265 of the cannulator within the tissues during the first stage 215 of biliary cannulation can be performed using a number of different visualization techniques, such as using ultrasound originated outside of a body of a patient or a camera placed inside of the patient’s body.

[0054] In prior-art procedures, , the second stage 225 of propagating 220 the cannula 265 through the tissues is blind and potentially dangerous. This is because medical imaging originated outside of the patient body does not have the required resolution to navigate the cannulator to miniature ducts without having a common point of reference between the outside medical imaging and the cannula, and also because the navigation through the tissues precludes usage of video sensors and other optical cameras.According to some embodiments, the depth sensor 120 can be used to sense a reflection of the signals emitted by the depth sensor 120 from an interface 260 separating tissues 250 from liquid in the ducts 230, 240. The depth sensor 120 is a time-of-flight sensor. In embodiments, a time-of-flight depth sensor is configured to emit waves penetrating the tissues in the neighborhood of the ducts, detect the echo of the emitted signal reflected from the medium change interface 260 and, if necessary, estimate the depth using speed of propagation of the emitted signals within the tissues 250.

[0055] Placement of the cannula within the tissues during the first stage of cannulation, which as is known from the prior art can cause the problem of the guided cannulation, can be turned into an advantage and used for see-through-tissues navigation. Specifically, techniques used for distance estimation to an object in a scene can be inversed to be used for depth estimation of an object after the sensor is placed within the object. Inter alia, this is because an object reflects an incident signal at an interface of a medium change. Typically, such a medium change is from a sparse medium to a dense medium. However, such a relationship can be reversed. As such, when a signal is originated outside of the object, such as in radar systems, the signal emitted by the radar is reflected at a border of the object to outside of the object. However, when a signal is originated inside the object, the signal is reflected at the border of the object into inside of the object. Hence, a sensor placed outside of the object act as a distance sensor to measure a distance to the object using time-of-flight principles, while a sensor placed inside an object acts as a depth sensor to measure depth of the object using the time-of-flight principles modified for signal propagation in a dense medium within the object.

[0056] Figure 3 shows a schematic of time-of-flight principles employed for guided cannulation. A sensor 310 includes a transceiver configured to emit a signal, e.g., an electromagnetic signal, to a scene of interest and to receive an echo of that signal reflected from the scene. When the sensor 310 is located outside an object 320 in the scene, the emitted signal 330 is reflected 335 at an interface 325 of a medium change between a medium of propagation of the emitted signal 330 and a medium of a structure of material of the object 320. In such a manner, the signal 330 is reflected outside of the object 320 and the reflected signal 335 indicates the distance from the sensor 310 to the object 320, and more specifically to the interface 325. The distance (actually twice the distance) can be calculated by timing the emitting 330 andreceiving 335 of the signal multiplied by the of propagation of the signal in the medium outside of the object 320.

[0057] The situation is inverted when the sensor 310 is placed inside the object 320, i.e., such that the signal emitted by the sensor 310 is emitted inside the object 320, e.g., after the interface 325. In this situation, the emitted signal 340 propagates within the object 320 to an interface 335 of a medium change between a medium of a structure of material of the object 320 and a medium outside of the object. In such a manner, the emitted signal 340 is reflected 345 inside the object, and the reflected signal 345 indicates the depth of the object with respect to the sensor 310. The depth (actually twice the depth) can be calculated by timing the emitting 340 and receiving 345 of the signal multiplied by the speed of propagation of the signal in the medium of the structure of the object 320.

[0058] In this disclosure, the object 320 comprises the tissues of a patient in a neighborhood of a target duct, and because the cannulator is placed within the tissues during the first stage of cannulation, a depth sensor can be used for visual navigation. Moreover, the depth sensor can be arranged in fixed orientation with the cannula, such that a change in the orientation of the cannula changes an orientation of the depth sensor. For example, the depth sensor can be rigidly attached to the cannula. In such a manner, the depth sensor has a common frame of reference with cannula, and the change of the orientation of cannula dictates what the depth sensor can sense. In addition, the time of propagation of the signal through the tissues can be determined in advance using simulation of based on physics of the structure of the tissues, such as duodenum 250 near the entrance to the bile duct.

[0059] In such a manner, the specifics of the first stage of biliary cannulation can transform the distance sensor into the depth sensor that can be used to guide the biliary cannulation during its more dangerous second stage.

[0060] In some embodiments, the depth sensor 120 is configured to emit a signal penetrating tissues over a distance sufficient to detect the orientation of the cannula when the depth of the tissues in a neighborhood of the duct with respect to the orientation of the cannula is within a range, e.g., less than a threshold. Because a duct carries liquid, which is a medium with different density from the density of the tissues, the signal is reflected at the border of the duct indicting the reduced depth of the surrounding tissues. Due to the fixed mutual orientation, the cannula can be guided toward the tissues having a depth within the range, so as to enter the duct. Forexample, the orientation of the cannula can be changed to reduce an error of the orientation of the cannula with respect to locations of the tissues with depth within the range and to point the cannula toward the locations of the tissues with depth within the range to enter the duct.

[0061] In contrast with distance sensors that may or may not sense an object in the scene, a depth sensor may always detect a border of the object due to the definite nature of the object’s shape. However, for guided cannulation, the total shape of the tissues surrounding the duct is not important and may even complicate the navigation.

[0062] Figure 4 shows a schematic of principles of bounded and / or binary depth sensing employed by some embodiments. The schematic 400 mimics an environment of bodily structures during biliary cannulation. The grey area represents tissues of the patient such as duodenum 250 near an entrance to the bile duct, while white area represents liquid in the ducts of the patient. An interface of a transition between gray and white areas represents medium change in the bodily structures of the patient.

[0063] In some embodiments, a bounded depth sensor is used to measure the depth of the tissues at a depth within the range 445. The range 445 can be determined based on specifics of the cannulation procedure. For example, for bile duct cannulation, the range can be 5 cm, because the bile duct is typically located about 5 cm from the initial placement of a cannula of a sphincterotome during the first stage of biliary cannulation. For example, a depth sensor 410 emits signals 415 and 430 propagating within the body of a patient in different directions. The signal 415 is reflected by a medium interface within the range 445, and the reflection 420 of the signal 415 is detected by the sensor 410. In contrast, the signal 430 passes a border 440 signifying the range 445 and fades 435 in the subsequent propagation. Even if the signal 430 is reflected by some medium interface in the body of the patient, the reflection of the signal beyond the range 445 from the depth sensor 410 is not detected by the sensor 410. This bounding allows distinguishing a duct of an interest from other bodily structures.

[0064] In some embodiments, the depth sensor is binary to detect wither the depth of the tissues with respect to orientation of the cannula is beyond the range or within the range. Based on the anatomical structure of a patient in the area near the entrance of the target duct(s), use of a bounded depth sensor enables the conclusion that if the depth of the tissues is within the range, such a reduction of the depth is due to the ducts and not something else. Hence, the distance to the ducts can be ignored and thebinary depth sensor can be used to indicate only the direction toward the entrance to the ducts. Specifically, the reflection 420 of the signal 415 and the absence of reflection of the signal 430 indicate the location of the depth tissues with depth within the range 445 from tissues with depth beyond the range. This information can be sufficient to orient the cannula toward the ducts of the patient.

[0065] These bounded and / or binary measurements simplify the guided cannulation and reduce the cost of manufacturing the guided cannulator. In addition, the bounded and / or binary depth sensing within a range adjusted for specifics of a medical procedure transforms a depth sensor into a navigation device for this specific medical procedure, such as biliary cannulation.

[0066] Figure 5A shows a schematic of a method for a guided navigation of a cannulator according to some embodiments. During the first stage of biliary cannulation, the cannula of cannulator is placed 510 in a duodenum in proximity of the duct allowing the depth sensor attached to the cannula to emit signals into the tissues in the neighborhood of the duct. Next, the method switches the depth sensor ON to emit the signal and processes 520 the data outputted by the depth sensor to estimate an error of the orientation of the cannula with respect to locations of the tissues with depth within the range.

[0067] As used herein, the error of the orientation is a difference between projections of a forward motion of the cannula, e.g., along its longitudinal axes, and a target orientation of the cannula allowing the forward motion of the cannula to enter the duct. The error of the orientation can be visualized on a display device 540 as a misalignment of a crossbar 535 indicating the direction of the forward motion of the cannula in its current orientation and an area 545 visualizing locations of the tissues with depth within the range with respect to the current orientation of the cannula. The area 545 is the area that returns the reflection of the emitted signal in bounding depthsensing. The error of orientation allows a user of the cannula to manipulate 530 the actuator to change the orientation of the cannula to reduce 525 the error and to point the cannula toward the locations of the tissues with depth within the range. After the crossbar 535 is aligned with the area 545, the cannulator can be moved forward to enter the duct.

[0068] Figure 5B shows a schematic of a differentiating procedure performed for a guided biliary cannulation of a cannulator according to some embodiments. In some situations during the guided biliary cannulation, changing 550 the orientation of the ofthe cannula results in detecting at least two non-overlapping areas of the tissues with depth(s) within the range that bounds detection of the reflection of the emitted signal. One area 545 corresponds to a ‘target’ bile duct. Another area 555 corresponds to a pancreatic duct that needs to be avoided. Such duplication can confuse the navigation. However, the area 545 corresponding to the bile duct can be identified 560 using the anatomical knowledge of different ducts with respect to each other and other bodily organs. After the area 545 is identified, the cannula can be guided 570 toward the identified area.

[0069] Different techniques can be used for imposing bounds on the depth sensing. For example, one technique uses a filter configured to limit maximum depth measured by the depth sensor based on a value of the tissue-penetrating range. For example, a filter can be a high frequency band filter. This technique can adapt a depth sensor to q different medical procedure by adjusting a filter. For example, one technique uses a depth sensor that emits signal in a millimeter wave spectrum. The distance of millimeter wave propagation is beyond what is necessary to detect a bile duct, but reflection of the millimeter wave can help to understand the initial placement of the cannula at the end of the first stage of biliary cannulation with respect to bodily organs. After such an initialization, the filter can limit echoes of the emitted signal only to reflections from medium interfaces within a predetermined range.

[0070] In some embodiments, the depth sensors can be selected or configured to emit signals that propagate through tissues over twice the distance of the range of target area to detect reflection of the signals only when the depth of the tissues is within the range. For example, the cannulator can be comprise a sphincterotome for bile duct cannulation. The range of a search for a bile duct from initial placement of the sphincterotome is typically less than 5 cm. Armed with this understanding, the technique uses a depth sensor that emits ultrasound signal able to penetrate the tissues and return back from border of the tissues located within 5 cm from the depth sensor, but would fade within the tissues if such a border is not found.

[0071] In some embodiments, the depth sensor includes an ultrasonic transducer that emits an ultrasound signal. The ultrasonic transducer is configured to transform an input electrical signal into the ultrasound and to convert an echo of the transmitted ultrasound into an output electrical signal. The amplitude of the output electrical signal indicates the depth of the tissues, such that when amplitude of the output electrical signal is above a threshold, the depth of the tissues is within the range. Insome implementations, the ultrasonic transducer is configured to emit the ultrasound having a frequency between 1.5 MHz to 3 MHz, such that the depth sensor is bounded to measure the depth of the tissues less than 5cm.

[0072] According to some embodiments, the use of an ultrasonic transducer can be advantageous for guided biliary cannulation due its small size and ability to provided bounded depth sensing. As the term is used herein, ‘ultrasonic transducers’, or ultrasonic sensors, are a type of acoustic sensor divided into three broad categories: transmitters, receivers and transceivers. Transmitters convert electrical signals into ultrasound, receivers convert ultrasound into electrical signals, and transceivers can both transmit and receive ultrasound.

[0073] In some embodiments, the depth sensor can include a piezoelectric sensor arranged to measure a physical parameter of a tissue and convert it to an electrical charge. In some embodiments, the depth sensor can include a light sensor. In some embodiments, the depth sensor can be effective to measure an electrical parameter of a tissue, such as, for example, and not exhaustively, conductivity or resistivity. In some embodiments, the depth sensor can include a fluid sensor arranged to measure a physical parameter of a tissue. In some embodiments, the depth sensor can include more than one type of sensor, e.g., configured to work in tandem and / or in succession. In some embodiments, electronic circuitry for conversion of analog signals to digital signals can be provided.

[0074] Different numbers and / or types of ultrasonic transducers can be to convert AC into ultrasound, as well as the reverse. For example, some embodiments use piezoelectric transducers and / or capacitive transducers. In piezoelectric transducers, piezoelectric crystals change size and shape when a voltage is applied. AC voltage makes piezoelectric crystals oscillate at the same frequency and produce ultrasonic sound. Capacitive transducers use electrostatic fields between a conductive diaphragm and a backing plate.

[0075] Figure 6A shows a block diagram of a piezoelectric transducer according to exemplary embodiments. The ultrasound is emitted in-situ within the tissue while the transducer surface has perfect coupling with the analyzed medium as so that the high-vibration amplitude is not required. In such a manner, this structure enables reduction of the dimensions of the transducer, to reduce disturbance of the tissues of the patient during cannulation procedure.Figure 6B shows a comparative illustration of dimensions of the transducer of Figure 6A. In some implementations, dimension of the piezoelectric transducer is of 3X2 mm or less.

[0076] The beam pattern of a transducer can be determined by the active transducer area and shape, the ultrasound wavelength, and the sound velocity of the propagation medium. Using time of flight measurement in near field, there is typically no need for focusing or collimation. Different implementations can use different number of ultrasonic transducers, and the beam pattern of the emitted signal can vary based on a number of transducers.

[0077] Figure 7A schematically illustrates an exemplary arrangement of a single ultrasonic transducer on a cannula. In this example, the ultrasonic transducer 710 is installed at angle between 20 and 45 degrees from the longitudinal axis of sphincterotome tip 720. This arrangement allows the forward-looking 715 sensing in order to detect the ducts directions before the sphincterotome tip physically reach the ducts.

[0078] Figure 7B schematically illustrates an example of a depth sensor including multiple ultrasonic transducers. In the non-limiting example, the depth sensor includes a set of ultrasonic transducers 730, 740, and 750 attached to the cannula in a pattern effective to form a synthetic aperture of the depth sensor oriented toward a direction of motion of the cannula. Such arrangements can increase an area observed by depth sensor without increasing the size of the transducers.

[0079] In implementations using a single ultrasonic transducer, the transducer 710 includes a transceiver. In embodiments using multiple ultrasonic transducers, the type of ultrasonic transducers can vary. Since piezoelectric materials generate a voltage when force is applied to them, they can also work as ultrasonic detectors. Some systems use separate transmitters and receivers, while others combine both functions into a single piezoelectric transceiver.

[0080] For example, in one arrangement, each of the ultrasonic transducers, such as transducers 730, 740, and 750 in the set of ultrasonic transducers, include an ultrasonic transmitter and an ultrasonic receiver. This embodiment simplifies implementation and maintenance of the depth sensor. In a different arrangement, the set of ultrasonic transducers includes one ultrasonic transmitter and multiple ultrasonic receivers to reduce cost and dimensions of components of the depth sensor.Figure 7C shows a cross-section of an exemplary cannula having a depth sensor including multiple ultrasonic transducers. In this example, the depth sensor includes four transducers 761, 763, 765, and 767 arranged in an equidistant circular pattern. In some embodiments, the transducers are fixedly attached to the cannula, using, e.g., resin, silicon or another suitable material. In this example, the transducers are arranged in a casing of the cannula for smooth propagation within the body of the patient.

[0081] Figure 8 shows a block diagram of a guided biliary cannulation system 800 in accordance with some embodiments. The guided biliary cannulation system 800 includes one or more processors 820 configured to execute stored instructions, as well as a non-transient (and, optionally, transient) memory 840 that stores instructions that are executable by the processor. The one or more processors 820 can include a single core processor, a multi-core processor, a computing cluster, or any number of other configurations. The non-transient memory 840 can include random access memory (RAM), read only memory (ROM), flash memory, or any other suitable memory storage media. The processor 820 is connected through a bus 806 to one or more input and output devices. These instructions implement a method for guided biliary cannulation according to different embodiments.

[0082] A network interface controller 850 is adapted to connect the guided biliary cannulation system 800 through the bus 806 to a network 890. Through the network 890, the depth data 895, e.g., outputs of a depth sensor can be downloaded and stored within the computer's non-transient storage system 830 for storage and / or further processing.

[0083] In some implementations, a human machine interface 810 within the guided biliary cannulation system 800 connects the system to a keyboard 811 and pointing device 812, wherein the pointing device 812 can include a mouse, trackball, touchpad, joy stick, pointing stick, stylus, or touchscreen, among others. The guided biliary cannulation system 800 can be linked through the bus 806 to a display interface 860 adapted to connect the guided biliary cannulation system 800 to a display device 865, wherein the display device 865 can include a computer monitor, camera, television, projector, mobile device, etc.

[0084] The guided biliary cannulation system 800 can also be connected to a control interface 870 adapted to connect the system to an actuator 875 of the cannulator.In some embodiments, the guided biliary cannulation system 800 is connected to an application interface 880 through the bus 806 adapted to connect the guided biliary cannulation system 800 to an application device 885 that can operate based on results of cannulation.

[0085] In some embodiments, the guided biliary cannulation system 800 includes a depth data filter 831 for preprocessing depth data 895 received from the depth sensor. The filter can include extracting the relative location of pixels of the depth image having the depth within a predetermined range. The sphincterotome tip is visible in x-ray imaging, while the duct is not; the depth sensor may have a visible mark to enable determination of the sensor direction. The depth sensor presents the duct map relative to the sphincterotome tip, enabling understanding of the tip direction.

[0086] Using the filtered data, an orientation error estimator 833 can determine an error in orientation between the current orientation of the cannula and its desired orientation, and / or determines an image representing that error for guided navigation of the cannula.

[0087] In one embodiment, the cannulator is operated by a user, e.g., a medical professional performing ERCP. In this embodiment, the results of the estimation 833 can be displayed on a display device 865 to assist in navigating the cannulator. The cannulator includes a human-to-machine interface allowing a user of the sphincterotome to change the tension of the wire. In addition, the depth sensor of the cannulator includes an output interface operatively connected to a display device 865 to display locations of the tissues having depth within the range. The locations are rendered on the display device with respect to the orientation of the cannula, such that that the change in the orientation of the cannula changes rendering of the locations. By observing the displayed relative locations, the user can estimate an error of the orientation of the cannula with respect to locations of the tissues with depth within the range and manipulate the actuator to change the orientation of the cannula to reduce the error and to point the cannula toward the locations of the tissues with depth within the range.

[0088] In some embodiments, data from the depth sensor can be used to navigate the cannula automatically or at least semi-automatically under the supervision of a medical professional. A system of guided biliary cannulation can include a controller 835 configured to change the tension of the wire based on the data from the depth sensor. In some implementations, the processor is configured to execute a neuralnetwork trained to transform the data from the depth sensor into values of the tension of the wire, such that the processor changes the tension of the wire according to the values determined by the neural network. In some implementations, the neural network is trained on training examples of depth images and corresponding control values needed to change the depth image to receive a desired depth image with reduce error of orientation. The depth sensor is mapping the duct and the media around it. Having enough data, the neural network is trained to defined the duct entrance from depth sensors maps more effectively, reducing the human factor errors even more The above-described embodiments of the present invention can be implemented in any of numerous ways. For example, the embodiments may be implemented using hardware, software or a combination thereof. When implemented in software, the software code can be executed on any suitable processor or collection of processors, whether provided in a single computer or distributed among multiple computers. Such processors may be implemented as integrated circuits, with one or more processors in an integrated circuit component. Though, a processor may be implemented using circuitry in any suitable format.

[0089] Also, the embodiments of the invention may be embodied as a method, of which an example has been provided. The acts performed as part of the method may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts are performed in an order different than illustrated, which may include performing some acts simultaneously, even though shown as sequential acts in illustrative embodiments.

[0090] Use of ordinal terms such as “first,” “second,” in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.

[0091] Although the invention has been described by way of examples of preferred embodiments, it is to be understood that various other adaptations and modifications can be made within the spirit and scope of the invention.

[0092] Therefore, it is the object of the appended claims to cover all such variations and modifications as come within the true spirit and scope of the invention.The present patent application has appended thereto 36 claims. In order to request a search in the USPTO as the international search authority, the claims are presented in single-dependent form only, without limitation, and in fact all combinations of inventice concepts are contemplated.

[0093] The present disclosure includes, without limitation, the following Inventive concepts, numbered 1-36 and listed below for convenient reference. It can be that some concepts disclosed hereinabove are not summarized in this section, but not being summarized in this section should not be taken as an indication that such concepts are not inventive or fall outside the disclosed scope of the embodiments. It may be that some of the Inventive concepts are introduced below for the first time for the sake of conciseness.

[0094] Inventive concept 1. A cannulator for a biliary cannulation, comprising: (a) a cannula; (b) a depth sensor coupled to the cannula at a fixed orientation thereto and configured to emit a tissue-penetrating signal in response to a user input, the depth sensor characterized by one or more power ratings and one or more operating frequencies effective to determine, for a given in-situ environment, a signalpenetration range of the depth sensor; (c) an actuator arranged to change an orientation of the cannula and of the depth sensor coupled thereto, the coupling being such that a change in an orientation of the cannula changes an orientation of the depth sensor; and (d) a control system comprising an output interface configured to provide information about tissues detected by the depth sensor, wherein the tissue-penetrating signal is effective to measure a depth of a tissue relative to the depth sensor when deployed in the given in-situ environment.

[0095] Inventive concept 2. The cannulator of Inventive concept 1, wherein the information about the detected tissues is about detected tissues within the signalpenetration range.

[0096] Inventive concept 3. The cannulator of Inventive concept 1, wherein the information about tissues is about detected tissues measured to be within the signalpenetration range.

[0097] Inventive concept 4. The cannulator of any one of the preceding Inventive concepts, wherein the information about the detected tissues includes at least one of: a location of the tissues, a measured depth of the tissues relative to the depth sensor, and a visual representation of the tissues.Inventive concept 5. The cannulator of Inventive concept 4, wherein the visual representation is of tissues within the signal-penetration range.

[0098] Inventive concept 6. The cannulator of any one of the preceding Inventive concepts, wherein the depth sensor is configured to detect wither a measured tissue depth is within the signal-penetration range.

[0099] Inventive concept 7. The cannulator of any one of the preceding Inventive concepts, wherein the signal-penetration range of the depth sensor is selectable through a controller of the depth sensor.

[0100] Inventive concept 8. The cannulator of any one of Inventive concepts 1 to 6, wherein the signal-penetration range of the depth sensor is selectable by selecting a depth sensor effective to emit the tissue-penetrating signal in the given in-situ environment within the selected signal-penetration range.

[0101] Inventive concept 9. The cannulator of any one of the preceding Inventive concepts, wherein the depth sensor is bounded or boundable to limit measurement of tissue depth to no more than a value of the signal-penetration range.

[0102] Inventive concept 10. The cannulator of any one of the preceding Inventive concepts, wherein the tissue-penetrating signal is in a millimeter wave spectrum.

[0103] Inventive concept 11. The cannulator of any one of the preceding Inventive concepts, comprising a filter configured to bound a maximum depth for measurement by the depth sensor.

[0104] Inventive concept 12. The cannulator of Inventive concept 11, wherein the bounded maximum depth is based on a value of the signal-penetration range.

[0105] Inventive concept 13. The cannulator of any one of the preceding Inventive concepts, wherein the depth sensor includes an ultrasonic transducer.

[0106] Inventive concept 14. The cannulator of Inventive concept 13, wherein a frequency of the tissue -penetrating signal is selected such the signal-penetration range is not larger than 5 cm.

[0107] Inventive concept 15. The cannulator of any one of Inventive concepts 1 to 12, wherein the depth sensor comprises an array of ultrasonic transducers coupled to the cannula in to a pattern effective to form a synthetic aperture of the depth sensor oriented toward a direction of motion of the cannula.

[0108] Inventive concept 16. The cannulator of Inventive concept 15, wherein each ultrasonic transducer in the array of ultrasonic transducers includes an ultrasonic transmitter and an ultrasonic receiver.Inventive concept 17. The cannulator of Inventive concept 15, wherein the set of ultrasonic transducers includes one ultrasonic transmitter and multiple ultrasonic receivers.

[0109] Inventive concept 18. The cannulator of any one of Inventive concepts 1 to 12, wherein the depth sensor includes a piezoelectric sensor.

[0110] Inventive concept 19. The cannulator of any one of Inventive concepts 1 to 12, wherein the depth sensor includes a light sensor.

[0111] Inventive concept 20. The cannulator of any one of Inventive concepts 1 to 12, wherein the depth sensor is arranged to measure an electrical parameter of a tissue, the electrical parameter comprising one of conductivity and resistivity.

[0112] Inventive concept 21. The cannulator of any one of Inventive concepts 1 to 12, wherein the depth sensor includes a fluid sensor.

[0113] Inventive concept 22. The cannulator of any one of the preceding Inventive concepts, wherein the cannulator comprises a sphincterotome, and the actuator comprises: (i) a flexible tube attached to the cannula such that the cannula forms a tip of the sphincterotome, and (ii) a wire extending at least in part within the tube and rigidly attached to the cannula such that a change of a tension of the wire causes a change of the orientation of the cannula.

[0114] Inventive concept 23. The cannulator of Inventive concept 22, comprising a handle assembly allowing a user of the sphincterotome to change the tension of the wire.

[0115] Inventive concept 24. The cannulator of Inventive concept 23, wherein the output interface is in electronic communication with a display device operative to render locations of the detected tissues within the signal-penetration range.

[0116] Inventive concept 25. The cannulator of Inventive concept 24, wherein display device is operative to render the locations with respect to the orientation of the cannula.

[0117] Inventive concept 26. The cannulator of any one of Inventive concepts 22 to 25, wherein the controller is programmed or programmable to generate a duct map relative to the tip of the sphincterotome, the duct map comprising a representation of a duct and at least some surrounding tissue.

[0118] Inventive concept 27. The cannulator of any one of Inventive concepts 22 to 26, wherein a controller thereof is programmed or programmable to change the tension of the wire based on data received from the depth sensor.Inventive concept 28. The cannulator of any one of Inventive concepts 22 to 27, wherein the controller is programmed or programmable to execute a neural network trained to translate the data received from the depth sensor into values of the tension of the wire, such that the controller is operative to change the tension of the wire according to the tension values determined by the neural network.

[0119] Inventive concept 29. The cannulator of any one of the preceding Inventive concepts, wherein the cannulator comprises an endoscopic access device including at least one of a catheter, a sphincterotome, a balloon, a biopsy device, a stent delivery catheter and a dilator.

[0120] Inventive concept 30. A method of performing a biliary cannulation, the method comprising: (a) providing the cannulator of any one of the preceding Inventive concepts; (b) placing the cannula in a duodenum in proximity to a target duct; (c) emitting the tissue-penetrating in proximity to the target duct; and (d) in response to data received from the depth sensor, employing the actuator to change the orientation of the cannula.

[0121] Inventive concept 31. The method of Inventive concept 30, wherein changing the orientation includes changing the orientation toward the locations of the tissues within the signal-penetration range of the depth sensor.

[0122] Inventive concept 32. The method of either one of Inventive concepts 30 or 31, further comprising: (i) detecting a plurality of non-overlapping areas of the tissues within the signal-penetration range of the depth sensor, (ii) identifying an area corresponding to the target duct, and (iii) guiding the cannula toward the identified area.

[0123] Inventive concept 33. The method of Inventive concept 32, wherein the detecting is subsequent to the employing of the actuator to change the orientation of the cannula.

[0124] Inventive concept 34. The method of any one of Inventive concepts 30 to 33, wherein the duct of the biliary tree includes one at least one of a bile duct, a pancreatic duct, and hepatic ducts of a liver.

[0125] Inventive concept 35. A cannulator comprising a sphincterotome and an ultrasonic transducer attached to a distal tip of the sphincterotome.

[0126] Inventive concept 36. The cannulator of Inventive concept 35, wherein the ultrasonic transducer is configured to emit an ultrasound signal at a frequency selected such that measurement of tissue depth is bounded to a range of less than 5cm.The present invention has been described using detailed descriptions of embodiments thereof that are provided by way of example and are not intended to limit the scope of the invention. The described embodiments comprise different features, not all of which are required in all embodiments of the invention. Some embodiments of the present invention utilize only some of the features or possible combinations of the features. Variations of embodiments of the present invention that are described and embodiments of the present invention comprising different combinations of features noted in the described embodiments will occur to persons skilled in the art to which the invention pertains.

Claims

CLAIMS1. A cannulator for a biliary cannulation, comprising:a. a cannula;b. a depth sensor coupled to the cannula at a fixed orientation thereto and configured to emit a tissue-penetrating signal in response to a user input, the depth sensor characterized by one or more power ratings and one or more operating frequencies effective to determine, for a given in-situ environment, a signal-penetration range of the depth sensor; c. an actuator arranged to change an orientation of the cannula and of the depth sensor coupled thereto, the coupling being such that a change in an orientation of the cannula changes an orientation of the depth sensor; andd. a control system comprising an output interface configured to provide information about tissues detected by the depth sensor, wherein the tissue-penetrating signal is effective to measure a depth of a tissue relative to the depth sensor when deployed in the given in-situ environment.

2. The cannulator of claim 1, wherein the information about the detected tissues is about detected tissues within the signal-penetration range.

3. The cannulator of claim 1, wherein the information about tissues is about detected tissues measured to be within the signal-penetration range.

4. The cannulator of claim 1 , wherein the information about the detected tissues includes at least one of: a location of the tissues, a measured depth of the tissues relative to the depth sensor, and a visual representation of the tissues.

5. The cannulator of claim 4, wherein the visual representation is of tissues within the signal-penetration range.

6. The cannulator of claim 1, wherein the depth sensor is configured to detect wither a measured tissue depth is within the signal-penetration range.

7. The cannulator of claim 1, wherein the signal-penetration range of the depth sensor is selectable through a controller of the depth sensor.

8. The cannulator of claim 1, wherein the signal-penetration range of the depth sensor is selectable by selecting a depth sensor effective to emit the tissue-penetrating signal in the given in-situ environment within the selected signalpenetration range.

9. The cannulator of claim 1, wherein the depth sensor is bounded or boundable to limit measurement of tissue depth to no more than a value of the signalpenetration range.

10. The cannulator of claim 1, wherein the tissue -penetrating signal is in a millimeter wave spectrum.

11. The cannulator of claim 1, comprising a filter configured to bound a maximum depth for measurement by the depth sensor.

12. The cannulator of claim 11, wherein the bounded maximum depth is based on a value of the signal-penetration range.

13. The cannulator of claim 1, wherein the depth sensor includes an ultrasonic transducer.

14. The cannulator of claim 13, wherein a frequency of the tissue-penetrating signal is selected such the signal-penetration range is not larger than 5 cm.

15. The cannulator of claim 1, wherein the depth sensor comprises an array of ultrasonic transducers coupled to the cannula in to a pattern effective to form a synthetic aperture of the depth sensor oriented toward a direction of motion of the cannula.

16. The cannulator of claim 15, wherein each ultrasonic transducer in the array of ultrasonic transducers includes an ultrasonic transmitter and an ultrasonic receiver.

17. The cannulator of claim 15, wherein the set of ultrasonic transducers includes one ultrasonic transmitter and multiple ultrasonic receivers.

18. The cannulator of claim 1, wherein the depth sensor includes a piezoelectric sensor.

19. The cannulator of claim 1, wherein the depth sensor includes a light sensor.

20. The cannulator of claim 1 , wherein the depth sensor is arranged to measure an electrical parameter of a tissue, the electrical parameter comprising one of conductivity and resistivity.

21. The cannulator of claim 1, wherein the depth sensor includes a fluid sensor.

22. The cannulator of claim 1 , wherein the cannulator comprises a sphincterotome, and the actuator comprises:i. a flexible tube attached to the cannula such that the cannula forms a tip of the sphincterotome, andii. a wire extending at least in part within the tube and rigidly attached to the cannula such that a change of a tension of the wire causes a change of the orientation of the cannula.

23. The cannulator of claim 22, comprising a handle assembly allowing a user of the sphincterotome to change the tension of the wire.

24. The cannulator of claim 23, wherein the output interface is in electronic communication with a display device operative to render locations of the detected tissues within the signal-penetration range.

25. The cannulator of claim 24, wherein display device is operative to render the locations with respect to the orientation of the cannula.

26. The cannulator of claims 22, wherein the controller is programmed or programmable to generate a duct map relative to the tip of the sphincterotome, the duct map comprising a representation of a duct and at least some surrounding tissue.

27. The cannulator of claim 22, wherein a controller thereof is programmed or programmable to change the tension of the wire based on data received from the depth sensor.

28. The cannulator of claim 22, wherein the controller is programmed or programmable to execute a neural network trained to translate the data received from the depth sensor into values of the tension of the wire, such that the controller is operative to change the tension of the wire according to the tension values determined by the neural network.

29. The cannulator of claim 1 , wherein the cannulator comprises an endoscopic access device including at least one of a catheter, a sphincterotome, a balloon, a biopsy device, a stent delivery catheter and a dilator.

30. A method of performing a biliary cannulation, the method comprising:a. providing the cannulator of claim 1 ;b. placing the cannula in a duodenum in proximity to a target duct;c. emitting the tissue-penetrating in proximity to the target duct; d. in response to data received from the depth sensor, employing the actuator to change the orientation of the cannula.

31. The method of claim 30, wherein changing the orientation includes changing the orientation toward the locations of the tissues within the signal-penetration range of the depth sensor.

32. The method of claim 30, further comprising:i. detecting a plurality of non-overlapping areas of the tissues within the signal-penetration range of the depth sensor,ii. identifying an area corresponding to the target duct, andiii. guiding the cannula toward the identified area.

33. The method of claim 32, wherein the detecting is subsequent to the employing of the actuator to change the orientation of the cannula.

34. The method of claim 30, wherein the duct of the biliary tree includes one at least one of a bile duct, a pancreatic duct, and hepatic ducts of a liver.

35. A cannulator comprising a sphincterotome and an ultrasonic transducer attached to a distal tip of the sphincterotome.

36. The cannulator of claim 35, wherein the ultrasonic transducer is configured to emit an ultrasound signal at a frequency selected such that measurement of tissue depth is bounded to a range of less than 5cm.

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