JAILED AIRWAY DETECTION AND AIRWAY STENT HOLE CUTTING GUIDE

A bronchial stent includes a first branch configured to widen, open, and/or mechanically support a first airway; an obstructive portion that, when the stent is deployed in the first airway, obstructs a second airway, the second airway forming a branching connection with the first airway; and a feature proximal to the obstructive portion, the feature configured to facilitate opening of the obstructive portion.

FIELD

This disclosure relates to airway stents and stent design. It relates more generally to surgical planning and to devices, systems, and methods for model-based stent design and placement.

BACKGROUND

Tracheobronchial protheses, also known as airway stents, support airway structural integrity where there has been tracheal collapse. They are typically deployed bronchioscopically and have tube-like shapes that mirror the interior of the airway as closely as possible for maximum effectiveness.

Traditionally manufactured stents have often fit poorly. They tend to be mass produced with an averaged shape to fit an average airway structure, yet actual airway shapes vary substantially. Poorly fitting stents can cause airway occlusion and scar tissue formation. They can dislodge and move within the airway, potentially cutting off other portions of it. Sometimes, they can even cause infection.

It is now possible to design these stents in silico, or by computer, to fit a particular airway in a particular patient. Computed tomography (CT) scans and/or magnetic resonance imaging (MRI) scans provide accurate three-dimensional (3D) representations of the patient's airway. Software uses the data from the scans to design stents that can better represent the shape of the imaged airway. 3D printing techniques generate a stent with that precise shape.

Nonetheless, these techniques still have notable limitations. In particular, fabricating and deploying computer-designed, 3D printed stents without the unintended consequence of “jailing off” or blocking an air passage is often impossible. Well-placed holes in the stent can address this drawback by restoring airflow to blocked passages. However, there are currently no accurate and reliable ways to do this. Physicians must guess at hole locations based on static measurements during the implantation or deployment procedure.

SUMMARY

Aspects of the present disclosure include a bronchial stent comprising a first branch configured to at least one of widen, open, and mechanically support a first airway, an obstructive portion that, when the stent may be deployed in the first airway, obstructs a second airway, the second airway forming a branching connection with the first airway, and a feature proximal to the obstructive portion, the feature configured to facilitate opening of at least a part of the obstructive portion.

The feature may form one of a circumference of and an outline of the at least a part of the obstructive portion. The stent may have an average thickness and the feature may have a thickness greater than the average overall stent thickness. The feature thickness may be at least one of ten percent more than the average overall stent thickness, twenty percent more than the average overall stent thickness, fifty percent more than the average overall stent thickness, twice the average overall stent thickness, three times the average overall stent thickness, and four times the average overall stent thickness. The feature may comprise a raised portion of the stent. The feature may comprise a perforation. The perforation may substantially outline the at least a part of the obstructive portion. The facilitating opening of at least a part of the obstructive portion may comprise facilitating mechanical removal of the feature from the stent.

The mechanical removal may comprise punching the obstructive portion with an instrument. The instrument may be a forceps. The removal may be performed prior to deploying the stent in the first airway. The stent may be made from a material and the feature may comprise the stent material. The stent may be made from a material and the feature may comprise a hole in the stent. The hole may substantially overlap the obstructive portion. The hole may be the at a least part of the obstructive portion. The hole may substantially encompass the obstructive portion. The material may be silicone. The stent may be 3D printed. The first and second airway may belong to a patient, and the first branch, the obstructive portion, and the feature proximal to the obstructive portion are configured to substantially fit at least the first airway. The configuring of the first branch, the obstructive portion, and the feature proximal to the obstructive portion may comprise designing the first branch, the obstructive portion, and the feature proximal to the obstructive portion using computer aided design (CAD). The CAD may use at least one of CT image data and MRI image data of the first and second airways. The feature may be proximal to an edge of the stent.

Configuring the feature to facilitate opening of at least a part of the obstructive portion may comprise designing the feature to avoid creating bridge-like portions in the stent. Designing the feature to avoid creating bridge-like portions may comprise creating a notch at the edge of the stent. The first branch, the obstructive portion, and the feature proximal to the obstructive portion may not be designed to fit a class of patients. The stent may comprise a reinforcing feature. The reinforcing feature may have a thickness greater than an average overall stent thickness. The reinforcing feature may be configured to obstruct at least one of the second airway and a third airway.

The stent may comprise a fitting portion, the fitting portion configured to accommodate another stent. The accommodating another stent may comprise at least one of fitting into a hole in the other stent, connecting to a connecting portion of the other stent, and encompassing an encompassing portion of the other stent. The accommodating another stent may comprise creating an air-tight seal between the stent and the other stent. The accommodating another stent may be accomplished while the stent is inside a patient. The accommodating another stent may create a stent architecture comprising the stent and the other stent. The stent architecture may comprise more than two stents. The stent may comprise an opening configured for a therapeutical purpose. The therapeutic purpose may comprise delivery of medicine.

Aspects of the present disclosure may comprise a method of creating the stent comprising designing the first branch, the obstructive portion, and the feature proximal to the obstructive portion using CAD, and 3D printing the stent. The designing may use CAD tools. It may use other software tools in conjunction with CAD. It may comprise using at least one of CT image data and MRI image data of the first and second airways. The CAD may design the stent to fit portions of a specific patient. The CAD may be used to segment at least one image of a region of interest in a patient to provide a three-dimensional model representing at least a portion of the first airway and at least a portion of the second airway, then select from a plurality of locations within the airway model and a corresponding plurality of diameters for the plurality of location, and finally construct a stent model from the selected locations and diameters.

The method may comprise generating the stent model as a cylindrical mesh that extends from a first location of the plurality of locations to a second location of the plurality of locations following a centerline of the three-dimensional airway model, with a diameter of the cylindrical mesh at a given point between the first location and the second location being a function of a first diameter associated with the first location, a second diameter associated with the second location, a distance between the first location and the second location, and a distance of the given point from the first location. The method may comprise placing a diagnosis marker, representing a stricture in at least one of the first airway and the second airway, the model generator selecting a thickness for at least a portion of the stent model according to a location and identity of the diagnosis marker. The segmenting may comprise segmenting the at least one image via a machine learning (e.g., convolutional neural network trained on images segmented by a human expert), the convolutional neural network receiving the at least one image of the region of interest and providing the three-dimensional airway model as an output. The method may comprise editing the stent model via graphical user interface to change one of a thickness of the stent model and a diameter of the stent model at the selected point.

Aspects of the present disclosure may further comprise a system comprising a processor, and a non-transitory memory storing computer executable instructions for performing the methods disclosed herein.

DETAILED DESCRIPTION

The present disclosure merely exemplifies the general inventive concepts using specific variations. Variations encompassing the general concepts may take various forms. The general concepts are not intended to be limited to the specific variations described herein.

As used herein, the term “model” can refer to a representation of an object created on a computer. In some instances, the model can be a three-dimensional representation of the object.

The term “coordinate system” can refer to a system of representing points in a space of given dimensions by coordinates.

As used herein, the terms “subject” and “patient” can refer, interchangeably, to any warm-blooded organism including, but not limited to, a human being, a pig, a rat, a mouse, a dog, a cat, a goat, a sheep, a horse, a monkey, an ape, a rabbit, a cow, etc.

Overview of Exemplary System for Generating Modeled Stents

FIG. 1shows a system100that may be used in computer aided design (CAD) for generating models of patient-specific (and other) stents and for 3D printing those stents, according to aspects of the present disclosure. As shown inFIG. 1, system100may be implemented by one or more computers140, which may be general purpose computers, computers adapted specifically for the purposes of CAD, and/or other programmable data processing apparatus. Suitable computers may include graphics modules and/or artificial intelligence (AI) modules particularly suited for graphical design. Computer140may include various input devices (not shown) such as one or more of a touchscreen, a mouse, a trackball, a keyboard, a microphone, and a gesture recognition interface. Computer140can include an output device (not shown), for example, one or more of a display, a speaker, and a printer.

System100includes at least one processor102and at least one non-transitory memory110storing CAD software116as well as executable instructions for designing airway stents. Non-transitory medium110can include any medium that is not a transitory signal and can contain or store the program for use by or in connection with the instruction or execution of a system, apparatus, or device. For example, non-transitory medium110can be an electronic, magnetic, optical, electromagnetic, infrared, semiconductor system, apparatus or device, a portable computer diskette, a random access memory, a read-only memory; an erasable programmable read-only memory (or Flash memory), or a portable compact disc read-only memory.

CAD software116may include any software suitable for providing components of a stent design tool described below that are executable by processor102, including an image interface for interfacing with imaging system101and image segmenter112, and graphic user interface (GUI)114. It may further include the image segmenter112and a model generator.

The executable instructions include image segmenter112that can segment images from imaging system101to provide three-dimensional models of the objects in those images. In one implementation, the imaging system101is a CT imaging system that provides one or more CT images to the imager interface, although it will be appreciated that the imaging system630can comprise any imaging system capable of providing three-dimensional models of an airway of a patient. In another variation, imaging system101is an MRI imaging system. Imaging system101may include multiple types of images and imaging systems (e.g., both CT and MRI). The images provided to the segmenter112may be a series of two-dimensional images from which a three-dimensional model of the airway of the patient can be constructed. They may also include some three-dimensional images.

Segmenter112may take an image of an airway, segment that image, and generate a 3D model of at least a portion of the airway. Often, the stent model will be based on the segmented image model of a particular patient's airway. However, this need not always be case. In some cases, the stent model may be more general and not specifically designed for any one patient. System100can display the airway model to the user via GUI114. Image segmenter112may also generate a 3D model of a stent design for display on GUI114. The image segmenter112can use any appropriate means for determining the boundaries of the airway within the received images. In one implementation, the image segmenter112includes a convolutional neural network, trained on CT images that have been segmented by a human expert, that produces the segmented airway model from the received CT images. The user may use the GUI114to edit and manipulate the design in real time.

The image segmenter112can utilize any suitable algorithm for segmenting input images. These algorithms include, for example, machine learning models. The machine learning models may be trained on example images segmented by human experts. Once trained, the models can provide the three-dimensional airway model based on input two- or three-dimensional images.

Suitable machine learning systems for this purpose include convolutional neural networks, recurrent neural networks, other neural networks, decision trees, and generalized adversarial networks. Use of other approaches such as energy minimization, clustering, and edge detection algorithms, may also generate the 3D models.

These aforementioned models and systems may be configured to automatically generate a stent model based on the 3D models of the airway. In addition, system100also includes human/user input in stent design. User input is largely facilitated by GUI114. The GUI114may provide controls to allow the user to rotate or zoom in or out from the model. This may facilitate design of the stent and/or visualization of the airway. In particular, GUI114may allow a user, such as a physician or technician, to determine a placement and size of the stent within the airway. Models may provide reference points or points of interpretation to aid user design. For example, the models may calculate certain reference locations within the stent for the user (e.g., geometric center, centerline, maximum thickness, minimum thickness, branching points of the stent, etc.). These reference locations may be based on the construction of the airway to facilitate an accommodating design. Examples of the latter include, for example, a point in the stent at which multiple branches of the airway meet.

Typical user stent design would proceed by a user, for example, first using the GUI114to select locations within an airway model generated from images by the segmenter112. Once selected, the user could assign a number of parameters (e.g., diameters, thicknesses, or features such as holes and perforations) for the stent model at each of the plurality of locations. Data can be entered manually and/or graphically. The GUI114may prompt the user to, for example, select four initial locations and corresponding diameters, representing a proximal end of the stent, a primary distal end of the stent, a secondary distal end of the stent, and a join location for first and second branches represented by the primary and secondary distal ends of the stent. This initial selection is merely exemplary. Initial selection can include more or fewer initial locations.

Once the initial locations are selected, CAD software (e.g., a model generator)116may construct a virtual stent model based on the selections and inputs. In one example shown inFIG. 2A, the model generator116generates an initial stent model200by representing user selected locations and associated input diameters as the base of a cylinder and connects the locations using a cylindrical mesh202. The model200may be fit using only user specified locations in the 3D airway image250. Alternatively, it may be fit according to a combination of user input and data from the 3D airway image250. A diameter of the stent may be a weighted linear combination of the selected first and second diameters, with the weights for each point determined from the distances from that point to each of the first and second ends of the stent. For example, the CAD software116can determine the diameter, dp, at a given point between the first location and the second location as dp=d1+(d2−d1)(l1,p/l1,2), where d1is the first diameter, d2is the second diameter, l1,2is the distance between the first location and the second location, and l1,pis the distance between the given point and the first location.

In one implementation, an approximate centerline (e.g., line250inFIG. 2Adiscussed below) of the stent model is created. The centerline may track a centerline of the model of the patient's airway. For a branching stent, at each end location, a cylindrical mesh with the selected diameter can be generated with the cylindrical meshes meeting at the fourth location. In one implementation, the cylindrical mesh follows the centerline of the airway, although other algorithms, such as a spline approach, can be applied to a set of points selected on the three-dimensional airway model to generate the centerline and diameter of the cylindrical mesh at each point based on the selected locations and diameters. Models may apply smoothing to avoid rapid deviation in the centerline of the stent present in the image model. A diameter of the cylindrical mesh202at points between the selected locations (not shown) can be determined, for example, via a polynomial or spline interpolation between the two locations.

The initial stent model may be displayed to the user via the GUI114for editing. In one example, the user selects additional locations (e.g., locations202a,202b,202c, and202d) within the initial stent design202. The user then changes stent parameters (e.g., diameter, thickness, presence of a hole, etc.) at each location202a,202b,202c, and202d. For example, the user may add additional branches to the stent (e.g., a new branch at location202b) if an airway branch is not mirrored in the original stent model200. The user may also change angles of branches at selected locations within the initial stent design300. Branches can be color coded to alert the user to the branch selected for editing. The stent thickness, inner diameter, and outer diameter can also be viewed at a selected point and edited via GUI114, either by directly entering a value, in which case the inner stent diameter remains fixed and the outer diameter is adjusted, or by changing either or both of the inner and outer stent diameters at a given point. The thickness of the stent model can also be adjusted globally.

In one implementation, users can place markers in the airway representing conditions within the airway that could cause stricture within the airway. In response to these markers, a thickness of the stent could be altered, based on the specific diagnosis at each region. For example, a tumor growing in the airway will require more radial force to hold it open that a disease that causes inflammation in the airway tissue. Each diagnosis can have a default stent wall thickness and width, representing a length of the stent that should be altered in response to a given diagnosis marker, that is used by the CAD Software116to generate the initial model, and the user can alter the thickness in the initial model via the GUI114. Once the user has finished editing the stent model, the user can approve the model via the GUI114.

The approved model can be provided to a manufacturer via a network interface or provided to a rapid prototyping system150, such as a 3D printer, to obtain a stent for use in the patient's airway. Any suitable 3D printer may be used. For example, suitable 3D printers include those that can print 3D objects using polymers such as silicone. Examples include those using a material jetting process. Additive manufacturing techniques can also be employed in stent fabrication. In addition, stents may be made from models in the context of the present disclosure in ways other than by 3D printing the stents themselves. For example, users may 3D print the negative of the stent model to create 3D molds. This may allow more flexibility in stent materials since moldable materials are not necessarily 3D printable. Moreover, 3D printing materials beyond those best for stents may be used to make the mold (e.g., ceramics and or carbon-based materials, other polymers).

An exemplary 3D printed real-world stent260is shown inFIG. 2B. Real-world stent260has approximately the same shape as stent model200inFIG. 2A. In particular,FIG. 2Bshows centerline204and positions202a-202dof stent model200superimposed on the photograph of stent260for comparison. Exemplary real-world stent260was 3D printed using silicone material. Silicone is a polysiloxane polymer that can be advantageous in stent applications because of the ease and accuracy with which it is 3D printed, its high biocompatibility, flexibility, relatively inert chemistry, and the fact that it does not support microbiological growth. Another property that may be advantageous, particularly during endoscopic deployment, is its transparency. Although stent260is made of 3D printed silicone, it is to be understood that this is merely exemplary. Any suitable, printable, and/or moldable stenting material may be used. Such materials include other polymers with high biocompatibility, flexibility, high tear strength, toughness, elongation, elasticity, and printability.

Design Considerations Regarding Jailed Airways

1. Jailed Airways Created in Modeling Patient-Specific Stents

Turning back toFIG. 2A, stent model200may create a jailed airway260. Jailed airway260is a portion of airway250that has been walled off or sequestered from the rest of airway250by the stent200, specifically by the stent200's obstructive portion206. As shown inFIG. 2A, jailing off airway260would prevent flow F from airway250. This may essentially forfeit use of jailed airway260in normal respiration.FIG. 2Cshows obstructive portion206from the perspective of jailed airway260. InFIG. 2C, obstructed flow F is out of the page.FIG. 2Bshows an approximate location of obstructive portion206in real world stent260.

FIG. 2Dshows a closeup of jailed airway260and obstructive portion206of stent200. If obstructive portion206remains when the stent200is deployed in the actual patient airway represented by250, it would prevent flow F of air to and from jailed airway260and the rest of the airway250. There may be some instances in which jailing an airway is advantageous (e.g., if the airway260is non-functional and/or exhibits a pathology that interferes with the rest of airway250). In many instances, however, it is advantageous to utilize as many airways as possible in respiration. Therefore, in many instances, it would be advantageous to redesign stent200so that airway260is no longer jailed.

2. Precision Design and Placement of Stent Holes to Allow Flow into Jailed Airways

A number of options are available to the user to address jailed airway260.FIG. 3Ashows a first option300. In option300, stent200is redesigned to have a hole310in place of obstructive portion206. Hole310can be designed into the stent model200before the stent is printed to form a real-world stent (e.g., stent260). In this way, stent200can simply be 3D printed (e.g., in silicone, as described in the context ofFIG. 2Babove) having hole310in the precise position that the model airway250indicates for the interface between stent200and jailed airway260(i.e., obstructive portion206of stent200). As shown inFIG. 3B, hole310may be sized and positioned to be precisely coincident with obstructive portion206. Precision sizing can be facilitated by the modeling process prior to 3D printing. The size of the hole depends entirely on the application. Generally, it may be advantageous to have larger holes, e.g., to support greater flow F between airway250and formerly jailed airway260. Therefore, having the hole as large as the obstructive portion of the stent (e.g., hole310which is the same size as obstructive portion206(FIG. 3B)) can be advantageous. In some cases, it may be advantageous for the hole to be even larger than obstructive portion206, again most likely to facilitate maximum air flow.

FIG. 3Cshows another variation in which hole312is centrally placed within obstructive portion206, but is smaller than obstructive portion206. This example is meant to show that there is no specific requirement for hole sizing within the model200. In some cases, restricted airflow may be advantageous so as, for example, not to have edges of the hole rub and grind into the jailed airway branch point (e.g., carina). In those cases, smaller holes such as312(FIG. 3C) would be preferable.

FIG. 3Dshows another instance where a smaller hole may be preferable.FIG. 3Dshows a hole314sized to fit the obstructive portion206. However, the location of the obstructive portion206inFIG. 3Dis relatively close to the edge202eof the stent200. Note that inFIG. 3Dthe location of obstructive portion206has been moved closer to edge202ethan its position inFIG. 2Ain order to facilitate discussion. In this case, a bridge-like structure202fof stent200is formed that is relatively thin and fragile. Such bridge-like portions202f, especially if made from silicone, may easily break and/or tear when stent200is deployed in a patient's airway. Fragments of a broken bridge-like structure202fmay be dangerous, uncomfortable, or irritating to the patient.

FIG. 3Eshows one way to eliminate problems associated with bridge-like structure202, e.g., by using smaller hole316. Smaller hole216is placed centrally located within obstructive portion206. This creates a much greater distance202gbetween hole316and edge202ethan the width of the bridge-like structure202fshown inFIG. 3Eand, therefore, providing bridge202gwith greater structural integrity. The portion of stent200corresponding to distance202gis much less likely to tear, rip, or fracture and cause related problems.FIG. 3Fshows another solution to the problem of bridge-like structure202f, specifically notch318. Notch318is a hole extending from318aall the way to edge202e. The C-shape gap in stent200shown inFIG. 3Fis merely exemplary. Notch318may have any suitable shape. As shown inFIG. 3F, notch318overlaps with the location of obstructive portion206sufficiently to provide flow through stent200(i.e., flow F between airway250and formerly jailed airway260inFIG. 2A). Notch318's position inFIG. 3Fis merely exemplary. For example, notch318may fully encompass obstructive portion206. It may, alternatively, encompass less of obstructive portion206than shown inFIG. 3F.

3. Design and Placement of Features Assisting Precise Stent Hole Creation

FIG. 4Ashows another feature400that can assist in opening the stent200to flow from jailed airway260. Feature400is shown in more detail inFIG. 4B. As shown inFIG. 4B, feature400includes a ring400aof raised stent material (element400bshows the height profile of raised material in ring400a). Ring400asurrounds a portion400cof feature400that is not raised. Ring400may be created by, for example, using the models to add extra thickness to stent200in the location of the ring400a. The extra thickness around ring400acreates a weakness in the inner circumference of400athat is directly adjacent to portion400c. This weakness creates a seam that can be broken once the stent200has been 3D printed. Breaking the seam400aremoves portion400cfrom the stent200thereby opening up portion400cfor airflow. This creates a hole in the stent200where portion400cused to be. Since portion400coverlaps with obstructive portion206, breaking the seam (400a) to form the hole allows airflow F between airway250and formerly jailed airway260.

As shown inFIG. 4C, ring400acan be substantially coincident and circumferential with respect to obstructive portion206. Ring400amay coincide exactly with obstructive portion206. Alternatively, ring400amay be larger (FIG. 4D) or smaller (FIGS. 4A and 4B) than obstructive portion206, depending on the particular application. Considerations for sizing of ring400aand the subsequent hole formed by removing portion400care similar, and in some cases identical, to those discussed in the context of sizing holes310-318above. Such considerations include, for example, restricting or promoting airflow F and/or prevent the formation of bridge-like portions. Similar and/or the same considerations also apply for the placement of ring400awith respect to obstructive portion206as those discussed above with regard to the relative placement of holes310-318. The hole formed by removing portion400cmay be placed in different positions with respect to the obstructive portion206in order to, for example, prevent the formation of bridge-like portions, etc. Ring400amay be placed such that the hole formed by removing portion400cforms a notch towards the edge202eof stent200similar to notch318(FIG. 3F). In this case, ring400would be placed proximal to202esuch that at least part of portion400coverlaps with edge202e. This is shown inFIG. 4E.

FIG. 4Fshows another version410of a ring construction with perforation. Individual perforations410a,410b, and410d(as well as the others shown inFIG. 4F) may help concentrate stress during punch out of the center portion410cto make a hole. In particular, differences in thicknesses between the thicker portions410dof the perforations and the thinner portions410eof the perforations, causing the stent200material to tear more readily upon the application of force. Perforations410a,410b, and410e, etc. can be printed in the same way, for example, as discussed above with respect to ring400a.

As in the case of ring410a, perforated ring410can be substantially coincident and circumferential with respect to obstructive portion206. Perforated ring410may be designed to coincide exactly with obstructive portion206. Alternatively, perforated ring410may be larger or smaller than obstructive portion206, depending on the particular application. Considerations for the size of perforated ring410and the subsequent hole formed by removing portion410care similar to those discussed above concerning the size of holes310-318and ring410a. The hole formed by removing portion410ccan be larger or smaller than obstructive portion206in order to, for example, restrict or promote airflow and/or prevent the formation of bridge-like portions. Similar and/or the same considerations also apply for the placement of perforated ring410with respect to obstructive portion206as those discussed above with regard to holes310-318and ring410a. The hole formed by removing portion410cmay be placed in different positions with respect to the obstructive portion206in order to, for example, prevent the formation of bridge-like portions, etc. Similar to the placement of ring400ainFIG. 3E, perforated ring410may be placed such that the hole formed by removing portion410cforms a notch (not shown but similar to notch318). In this case, perforated ring410would be placed proximally to202esuch that at least part of portion410coverlaps with edge202e(not shown).

Stent holes (e.g., holes310,312,314,316, and318), notches (e.g., notch318), and features400and410are represented above generally with a rounded or circular appearance. While a rounded or circular shape may have certain advantages (e.g., simplicity and symmetry), it is to be understood that these shapes are merely exemplary. Stent holes (e.g., holes310,312,314,316, and318), notches (e.g., notch318), and features400and410may have any suitable shape. Suitable shapes include slits, triangular or rectangular holes, flaps, x-shapes, etc. One consideration with regard to the shape of features400and410is the shape of the tool used to punch holes out of them. Features400and410may, for example, have shapes that mirror the end of this tool, or be shaped to interact with the tool in a specific way. It is also to be understood that any combination stent holes (e.g., holes310,312,314,316, and318), notches (e.g., notch318), and features400and410may be employed on a stent design. Stent designs may have multiple holds, notches, and features depending on the particulars of the airway in which they are deployed. These features may also be incorporated on portions of the stent with varying thicknesses, as discussed in more detail below. Any of these changes can be accomplished by changing the thickness in the model, and via 3D printing.

Modifying Other Aspects of the Stent

FIG. 5Ashows one way a thickness of the printed walls of the stent200can vary. As shown inFIG. 5A, the thickness500aof a portion of stent200above position202bis considerably less than the thickness500bof a portion below position202bof the stent200. Both thicknesses500aand500bare shown relative to the outer surface S of the stent and an inner cavity500cof the stent200. Thickness500bmay be made greater than thickness500ain the model design process, as discussed above, prior to printing. In the example discussed above, the user would simply select positions associated with thicknesses500and500band adjust accordingly.

Different portions of stent200may have different thicknesses for different reasons. One reason is that some sections of airway250may need more mechanical support than others. For example, portions of airway250that have collapsed may need to be supported by an extra strong (thick) portion of stent200. Portions of the airway250showing pathology making them prone to future collapse may also need extra support. Portions of the airway250with increased airflow may also need the support of extra thickness. In some cases, it may be advantages to thicken portions of the stent where severe bending or shape change takes place based on the pathology of the patient and the airway locale. Some examples may include progressive malignant (tumor) or benign disease (cyst) where the stent needs to resist the progression of the disease. Lower wall thickness may be required for diseases such as malacia where there is a loss of structure of the airway and the stent is providing more rigidity to the structure rather than resist progressive disease. Although particular portions inFIG. 5Aare shown as having an increased thickness, it is to be understood that any other portion of stent200may have an increased thickness depending on application. For example, the thickness may be increased or decreased at any of positions202a-202d. Any of these changes can be accomplished by changing the thickness in the model, and via 3D printing.

The thickness of any region may be a number of percent (e.g., 5, 10, 15%) greater than an average thickness of the overall stent (e.g., thickness500ashown inFIG. 5A). The thickness of any region may be multiple times the average thickness, e.g., two, three, for, or ten times. In the same way, any portion of stent200may have a decreased thickness (not shown). Reasons for decreasing the thickness of a portion include increasing flexibility of the stent at that portion, conserving material (e.g., for weight and cost considerations). The thickness of any region may be less than the average thickness by a number of percent (e.g., 5, 10, 15%). The thickness of any region may be fractions of the average thickness, e.g., one half, one third, one fourth, or one tenth.

FIG. 5Ashows increasing the thickness of a portion of stent200near location202bby increasing the thickness in a convex manner (i.e., by thickening the outer wall of stent200, but leaving the inner cavity500cthe same). This method has the advantage of adding thickness without restricting airflow. However, it may make the stent200harder to position during endoscopic placement.

FIG. 5Bshows an alternative method of increasing the thickness of stent, again in a lower portion with respect to location202b. InFIG. 5B, the increase in thickness (compare510aand510b) results from decreasing the radius of the interior cavity from510din the portion above position202bto510ein the portion below position202b. This decrease in cavity radius results in a greater thickness of stent wall at510bthan510a, even though the outer wall is not made convex. Advantages to this method of increasing thickness include imparting greater structural stability and strength without rendering stent200less maneuverable during deployment. Potential disadvantages may include increased restriction of airflow in the stent.

AlthoughFIGS. 5A and 5Bshow particular methods of increasing thickness on exemplary portions of stent200, it is to be understood that these methods can be applied to increase thickness on any other portion of stent200. Moreover, the two methods are not mutually exclusive and may be applied together. They may also be applied in conjunction with other methods of increasing thickness (e.g., in conjunction with ring400aformation, etc.) discussed above. They may be applied for the same advantages and reasons discussed above and to the same degree as discussed above.

In addition to the above, increasing thickness of the stent200according to any method disclosed herein may be done to help seal off and/or obstruct an airway. For reasons discussed above, it may sometimes be advantageous to obstruct an airway. These reasons include if the airway is somehow compromised and/or functioning in a way that is determinantal to other airways. For example, it may be advantageous to seal off an airway when a lobectomy has occurred and the airway does not terminate into lung but rather pleural space. Sealing an airway may also be advantageous in cases with patients with Chronic obstructive pulmonary disease (COPD) and emphysema localized to specific lung lobes. Regardless of the reasons, increasing the thickness of the stent200in the vicinity of the affected airway may be advantageous for obstructing or sealing the affected airway. The thickness may be increased by any method disclosed herein. The deliberately obstructed airways may include jailed airway260or any other portion of airway250(FIG. 2A).

The openings discussed above (e.g., any of the holes310,312,314, and316, notch318, and features used to create holes400and410) may be used to create holes for purposes other than un-jailing jailed airways260. Other therapeutic modalities, in particular, are contemplated within the scope of the present disclosure. For example, holes created using the above-described techniques may be used for the delivery of medicine, diagnostics, and/or nutrients to portions of the airway.

Multiple stents can be designed for one patient in the same or successive deployments, then interlocked together to form a composite stent architecture. This can be advantageous because designing a single stent for multiple airways is nearly impossible due to difficulty of placement of such a stent.

As shown inFIG. 2A, airways (e.g., airway250) can be extremely complex.FIG. 2Arepresents a real airway in a real patient. Airways can vary substantially in angulation, branching, and diameter. The branching may not be dichotomous but rather random and multiple airways may join in one carina all going in different anatomical directions. Airway250shows at least eight branches (see, e.g., branches250a,250b,250c, and260) stemming from the main branch250. Any of these branches may independently need stents. In many cases, more than one of the branches need stents. Yet, the airway250(and airways in patients, more generally) has complex, cavernous interior spaces that do not lend themselves to deploying multi-branch stents. Multi-branch stents require a level of physical complexity that simply cannot, in many cases, be endoscopically deployed.

Instead, multiple stents can be designed with interlocking features according to the principles disclosed above. Stent holes (e.g., holes310,312,314,316, and318), notches (e.g., notch318), and features400and410can all be designed with complex shapes according to any of the design principles described herein. These complex shapes can include interlocking or fitting portions that allow two or more stents to create a multi-airway structure in situ during endoscopic deployment. These interlocking or fitting components can be designed to form air-tight seals creating a stent superstructure or architecture that dramatically improves flow in the airway in a way separately deployed stents would not. The connecting, interlocking or fitting may be performed inside the patient before, during and subsequent to deployment.

Preparing and Deploying the Stent

As discussed above, variations400and410may require punching and removing of portions400cand410c, respectively, in order to create a hole in the vicinity of jailed airway260. Creating this hole prevents the jailing of airway260. The hole generally needs to be created by applying force to variations400and410, particularly at portions400cand410c. As discussed above, the applied force causes stress concentrations in and around400aand the perforations of410that lead to tearing, fracture, and separation of portions400cto410cto create a hole.

Punching of400cand410cto create holes in the stent to accommodate, e.g., jailed airway260may be accomplished by any suitable means. One suitable method is to use forceps (e.g., Dutau Forceps or Lymol Stent Cutting Forceps). However, it should be understood that any suitable hole punching procedure and/or tool can be used. Since, as discussed above, the modeling and printing of the model guides formation of the hole, increased accuracy is achieved. The hole punching can be accomplished prior to deployment or implantation since it is based on accurate models of the airway passages based on diagnostic imaging. In some cases, hole punching may also or alternatively be performed during deployment and/or in situ.

Overview of Processes and Methods

Another aspect of the present disclosure can include methods of generating a stent for a patient's airway, as shown inFIGS. 6 and 7. Methods, processes or algorithms (herein used interchangeably)600ofFIGS. 6 and 700ofFIG. 7are illustrated as process flow diagram with flowchart illustrations. For purposes of simplicity, the methods are shown and described as being executed serially. However, it is to be understood and appreciated that the methods in the present disclosure are not limited by the illustrated order as some steps could occur in different orders and/or concurrently with other steps shown and described herein. Moreover, not all illustrated aspects may be required to implement the methods.

Algorithm600is a stent design process according to aspects of the present disclosure. In step602, an image of a patient's airway is collected by any suitable diagnostic technique discussed herein (e.g., CT scan and/or MRI). Step602may also analyze and input a generalized airway system for generating a stent model that is not configured for a particular patient. Next, in step604, the image data collected in step602is segmented by CAD software (and/or any other suitable algorithm). A 3D model of the patient (or generalized) airway is then generated based on the segmentation. In step606, optionally, user input is requested. User review of the airway preempts errors or exaggerations that may arise from imaging noise and/or aberrations. The user also may select, at this point, aspects or locations of the model that would benefit from direct entry of user data. In step608, the algorithm prompts the user to enter aspects and parameters of the model pertaining to the locations selected in step606(e.g., diameters of the mesh model of the stent202shown inFIG. 2A). The aspects and parameters may include any of the aspects and parameters disclosed herein, including those pertaining to jailed airway remediation (e.g., any of the methods and techniques disclosed for mediating jailed airway260). The algorithm then generates an initial stent model in step610. Either the algorithm and/or the user may identify jailed airways in step612. In step612, the algorithm may also prompt the user for other edits to the model (e.g., correction of modeling errors, exaggerations, problems, reinforcements of thickness as discussed in the context ofFIGS. 5A and 5B, locations of any holes310-316, notches318, and/or features400and410). In step614, the algorithm incorporates the user edits and any other post-step610input information into generating a final model for 3D printing and rapid prototyping (e.g., element150ofFIG. 1).

FIG. 7presents a method700for printing, preparing, and deploying a stent within aspects of the present disclosure. At step702a finalized stent model (e.g., the final model generated in step614of method600) is input to a 3D printing system (e.g., as part of rapid prototyping150). Any suitable 3D printing system may be used. 3D printing systems that can fabricate shapes with precision using silicone and other inert polymers are preferred. At step704, the 3D printer prints the stent. The printed stent at this stage may have a number of features (e.g., features400and410) that need additional steps before the stent can be deployed. These additional steps, including punching of holes in features400and410, is performed at step706. Hole punching features400and410may be accomplished, as discussed above, by using forceps or any other suitable tool. Hole punching is typically done prior to deployment, i.e., outside of the patient. However, in certain instances, hole punching may be contemplated in situ. Other preparation steps in step706may include smoothing any roughened features caused by the 3D printing and stent handling, as well as general surface preparation (e.g., adding coatings for various purposes, including to administer medicine or other therapeutics, to prolong stent life, provide additional reinforcement, and/or to prevent infection). These steps would typically be performed ex situ. In step708, the stent is deployed inside the patient's airway. Typical deployment uses an endoscopic method. However, any suitable method of stent deployment is within the scope of the present disclosure. Once deployed, in step710, if applicable, the stent is connected to other stents and/or stent architectures as described above. This step is only applicable when the stent is to be used in conjunction with others. It is performed by interlocking the features of the stents (e.g., holes310,312,314,316, and318, notches (e.g., notch318), and features400and410) such that they join the stents. The joining can be done endoscopically. Typically, joining creates an air-tight seal between the joined stents.

One or more blocks of the flowcharts600and700, and combinations of blocks in the block flowchart illustrations inFIG. 6, can be implemented by computer program instructions. These computer program instructions can be stored in memory and provided to a processor of a general purpose computer, special purpose computer, and/or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer and/or other programmable data processing apparatus, create mechanisms for implementing the steps/acts specified in the flowchart blocks and/or the associated description. In other words, the steps/acts can be implemented by a system comprising a processor that can access the computer-executable instructions that are stored in a non-transitory memory.

The methods can be implemented in hardware and/or in software (including firmware, resident software, micro-code, etc.). Furthermore, aspects of the present disclosure may take the form of a computer program product on a computer-usable or computer-readable storage medium having computer-usable or computer-readable program code embodied in the medium for use by or in connection with an instruction execution system. A computer-usable or computer-readable medium may be any non-transitory medium that can contain or store the program for use by or in connection with the instruction or execution of a system, apparatus, or device. As an example, executable code for performing the methods can be stored in a non-transitory memory of a computing device and executed by a processor of the computing device and/or another computing device.