Abstract:
Systems and methods for marking a body cavity. In one embodiment, a system includes means for inspecting a body cavity, and means for visibly marking the body cavity so as to convey visual information regarding the body cavity. In one embodiment, a method includes inspecting a body cavity and marking the body cavity with a marking material to provide a visual indication regarding the cavity. In one embodiment, a marking material for marking a body cavity includes a radiopaque contrast agent that is viewable through fluoroscopy and a colored dye that is viewable using an internal viewing device.

Description:
BACKGROUND 
     Surgeons are often called upon to inspect internal body cavities to diagnose or remedy a medical condition. For example, a surgeon may inspect the calices of a patient&#39;s kidney to search for and remove kidney stones. 
     In the case of kidney inspection and stone removal, the surgeon may need to inspect each of multiple calices of the kidney.  FIG. 1  illustrates a typical kidney  10  that is representative of a kidney that a surgeon may need to inspect. As is shown in  FIG. 1 , the kidney  10  includes an outer capsule  12  that surrounds a renal cortex  14  in which a plurality of minor calices  16  are formed. Each of the minor calices  16  may extend from a major calyx  18  that, in turn, extends from the renal pelvis  20 . The renal pelvis  20  is connected to the ureteropelvic junction  22 , which leads down to the ureter  24 . 
     To inspect the kidney  10 , the surgeon will normally insert a viewing device, such as an endoscope, into each of the calices  16  of the kidney  10  to enable visual inspection of each calyx for stones. Such a viewing device may be inserted into the kidney via the urinary tract. Fluoroscopy may also be used during such a procedure to aid the surgeon in positioning the viewing device in the desired portion of the kidney  10 . 
     It is common for surgeons to use a top-to-bottom approach when inspecting the kidney  10 . In such a procedure, the surgeon checks a first calyx  16 , determines whether it contains any stones, and, assuming it does not, checks the next calyx. When a stone is discovered, it is fragmented, if necessary, and removed from the calyx  16  using a retrieval device. This process continues from the top  26  of the kidney  10  to the bottom  28  of the kidney until each calyx  16  has been inspected and every stone or stone fragment has been removed. During the process, the surgeon or the surgical staff tracks which calices  16  have been inspected in an effort to ensure that each calyx is checked. 
     Because there may be many different calices  16  to inspect and because the position of the viewing device can only be inferentially determined from the images captured by the viewing device and any captured fluoroscopic images, it is often difficult for the surgeon to know with any certainty whether a given calyx has or has not been inspected. As a result, the surgeon may revisit one or more calices one or more times to ensure that it has been checked and does not contain any stones. This “double-checking” lengthens the time required to complete the procedure, thereby increasing risk and/or discomfort to the patient. 
     Even in cases in which the surgeon and staff are careful in keeping track of which calices  16  have been inspected, it is possible for them to make a mistake that results in one or more calices not being inspected. In such a case, one or more stones or stone fragments may remain which can act as seeds for further stone formation. 
     In cases in which a stone must be fractured before being removed, for instance if the stone is too large to be removed as a single piece, lithotripsy may be performed to break the stone into smaller fragments. When lithotripsy is performed, it is possible for a stone fragment to be propelled into a calyx  16  that has already been checked. If this happens, one or more stones or stone fragments may remain which, again, can act as seeds for further stone formation. 
     SUMMARY 
     Disclosed are systems and methods for marking a body cavity. In one embodiment, a system includes means for inspecting a body cavity, and means for visibly marking the body cavity so as to convey visual information regarding the body cavity. 
     In one embodiment, a method includes inspecting a body cavity, and marking the body cavity with a marking material to provide a visual indication regarding the cavity. 
     In one embodiment, a marking material for marking a body cavity includes a radiopaque contrast agent that is viewable through fluoroscopy, and a colored dye that is viewable using an internal viewing device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosed system and method can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale. 
         FIG. 1  is a schematic cross-sectional view of a kidney. 
         FIG. 2A  is a schematic cross-sectional view of a kidney, illustrating inspection of a first calyx using a viewing device. 
         FIG. 2B  is a schematic cross-sectional view of a kidney, illustrating marking the first calyx with a marking material. 
         FIG. 2C  is a schematic cross-sectional view of a kidney, illustrating inspection of a second calyx using a viewing device. 
         FIG. 2D  is a schematic cross-sectional view of a kidney, illustrating removal of a stone from the second calyx using a retrieval device. 
         FIG. 2E  is a schematic cross-sectional view of a kidney, illustrating marking the second calyx with a marking material. 
         FIG. 3A  is a schematic cross-sectional view of a kidney, illustrating marking a third calyx with a marking material. 
         FIG. 3B  is a schematic cross-sectional view of a kidney, illustrating removal of a stone from the third calyx using a retrieval device. 
         FIG. 4  is a schematic cross-sectional view of a kidney, illustrating filling of a group of calices with a first marking material, and filing a separate calyx with a second marking material. 
     
    
    
     DETAILED DESCRIPTION 
     As is described in the foregoing, it can be difficult to keep track of which of multiple body cavities have or have not been inspected during a surgical procedure. As is discussed in the following, however, the progress of such inspection can be clearly indicated using a marking material. By way of example, such a marking material can be used to mark one or more cavities that have already been inspected. Alternatively, a marking material can be used to mark one or more cavities of interest, for example that contain an object to be removed. In a further alternative, a first type of marking material can be used to mark cavities of a first type (e.g., that contain objects to be removed) and a second type of marking material can be used to mark cavities of a second type (e.g., that contain no objects to be removed). The marking material contains a marking substance that can be viewed with a viewing device and/or that can be viewed fluoroscopically. In the former case, the marking substance may comprise a dye. In the latter case, the marking substance may comprise a contrast agent. 
     Referring now to the drawings, in which like reference numerals identify corresponding components,  FIGS. 2A-E  illustrate various steps in an embodiment of a method for inspecting a plurality of internal body cavities. In the example of  FIGS. 2A-2E , the body cavities comprise calices of a kidney that are to be inspected for kidney stones. Although a kidney application is shown in the figures and is described in detail herein for purposes of example, the systems and methods of this disclosure can be applied to other internal body cavities. Therefore, the present disclosure is intended to cover applications beyond kidney inspection and stone removal. 
     Beginning with  FIG. 2A , illustrated is the kidney  10  first described in relation to  FIG. 1 . As is described above, the kidney  10  comprises a plurality of calices  16  that may comprise kidney stones that are to be removed (none visible in the view of  FIG. 2A ). While the bodies of some of the calices  16  are visible in  FIG. 2A , only the openings of other calices are visible (indicated by circles in  FIGS. 2A-2E ). 
     As is illustrated in  FIG. 2A , an internal viewing device  30  has been inserted into the kidney  10  via the ureter  24 . By way of example, the viewing device  30  comprises a ureteroscope that has been inserted through a ureteral access sheath  32  that has been inserted into the urinary tract via the external meatus. Although use of an access sheath  32  is depicted in  FIG. 2A , the viewing device  30  could, alternatively, be inserted through the urinary tract without the access sheath. Use of the access sheath  32 , however, simplifies insertion and removal of the viewing device  30 , particularly in cases in which the viewing device must be repeatedly inserted and removed, as when removing multiple stone fragments. In alternative embodiments, the viewing device  30  can be introduced into the kidney  10  using other methods, for instance percutaneously. 
     With further reference to  FIG. 2A , the viewing device  30  has been maneuvered into a first calyx  34  of the upper portion of the kidney  10 . That calyx  34  may, for example, be a suitable calyx to start with in a top-to-bottom inspection procedure, such as that described in the foregoing. As is shown in  FIG. 2A , the calyx  34  is clear of any stones or other objects that would require removal. Because of this, no further action is required in relation to the calyx  34 , and the surgeon may move on to the next calyx  16  of the kidney  10 . 
     As is described above, it can be difficult for a surgeon or the surgical staff to keep track of which calices  16  have or have not been inspected. To avoid this problem, the surgeon can mark the calyx  34  prior to moving on to the next calyx  16 . By marking the calyx  34  in this manner, the surgeon can readily determine that he or she has already inspected that calyx and understand that no further inspection of the calyx is necessary. In some embodiments, marking can be achieved by filling the calyx  34  with a marking material. Such a procedure is illustrated in  FIG. 2B . As is indicated in that figure, the calyx  34  has been filled with a marking material  36 . Although the entire calyx  16  is shown filled with that marking material  36 , the calyx (or other cavity) could be marked by filling only a portion of the calyx with the marking material. For example, the marking material  36  could be used to fill just the entrance to the calyx  34 , if desired. 
     The marking material  36  can be deposited using various different devices and techniques. In some embodiments, the marking material  36  is injected into the calyx  34  (or other cavity) using a working or irrigation channel of the viewing device  30 . In other embodiments, the marking material  36  is delivered using a separate catheter that is inserted through the urinary tract (not shown). In still further embodiments, the marking material  36  is percutaneously injected into the desired site using an external injection device, such as a syringe. 
     Irrespective of the manner in which the marking material  36  is deposited, the marking material contains a marking substance that is visible using one or both of the viewing device and fluoroscopy. In some embodiments, the marking material  36  comprises one or more dyes that enable the surgeon to readily identify the marking material when viewing the kidney interior using the viewing device  30 . Suitable dyes include, for example, methylene dyes, such as methylene blue and methylene red. When such a dye is used, the surgeon will be able to readily determine that the calyx  34  has already been inspected upon later returning to that area of the kidney  10 . 
     In some embodiments, the marking material  36  further or alternatively includes a contrast agent that enables identification of the marking material, and the cavity in which it is placed, through fluoroscopy. The term “contrast agent” refers to any radiopaque material capable of being fluoroscopically monitored. The contrast agent can be either water soluble or water insoluble. Examples of water soluble contrast agents include metrizamide, iopamidol, iothalamate sodium, iodomide sodium, and meglumine. Examples of water insoluble contrast agents include tantalum, tantalum oxide and barium sulfate, each of which is commercially available in the proper form for in vivo use. Other water insoluble contrast agents include gold, tungsten and platinum. As with the dye, the contrast agent assists the surgeon in determining which calices  16  (or other cavities) have already been inspected. 
     In some preferred embodiments, the marking material  36  is in liquid form prior to deposition, but forms a gel after or during deposition. In some embodiments, the marking material  36  can be a temperature-sensitive material that is in liquid form below normal body temperature, but that forms a gel at or above body temperature. Such materials include lower critical solution temperature materials, such as polyoxyethylene-polyoxypropylene (PEO-PPO) block copolymers. When such a material is used, it can be delivered to the calyx  34  in liquid form, and then transition into a gel as it is heated by the kidney  10 . Alternative temperature-sensitive materials include those that are in liquid form at or above normal body temperature, but form a gel below body temperature. In such a case, the material can be deposited within the calyx  34  and cooled to form a gel. Examples of such materials include gelatin materials. 
     In other embodiments, the marking material  36  comprises two separate component that, when mixed, form a gel. One example of such materials are those that include crosslinkable polymers that form a gel when contacted with a crosslinking agent. Crosslinkable polymers that may be suitable for use in the invention include both ionically crosslinkable and non-ionically crosslinkable polymers. Crosslinking agents that may be employed include both ionic crosslinking agents and non-ionic crosslinking agents. Ionically crosslinkable polymers include anionic crosslinkable polymers and cationic crosslinkable polymers that may be used in conjunction with anionic crosslinking agents and cationic crosslinking agents, respectively. 
     Irrespective of the type of marking material  36  that is used, the marking material is a temporary implant that it is automatically or manually removed once it is no longer needed to identify the calyx  34  (or other cavity). For example, in cases in which the marking material  36  is a temperature-sensitive material, the material will slowly degrade within the kidney and be excreted. Optionally, the speed with which the temperature-sensitive gel breaks down can be increased by either cooling or heating the marking material  36 , depending upon whether the material forms a gel at higher or lower temperatures. 
     In cases in which the marking material  36  comprises two separate components that together form a gel, breakdown of the marking material can, for example, be achieved by providing a third material that degrades the gel. For instance, if the marking material  36  includes a crosslinkable polymer, a suitable de-crosslinking agent may be used to dissolve the gel, in which case the material will again be excreted. Suitable de-crosslinking agents include sodium phosphate, sodium citrate, inorganic sulfates, ethylene diamine tetraacetic acid and ethylene dime tetraacetate, citrates, organic phosphates (e.g., cellulose phosphate), inorganic phosphates (e.g., pentasodium tripolyphosphate, mono- and di-basic potassium phosphate, sodium pyrophosphate), phosphoric acid, trisodium carboxymethyloxy succinate, nitrilotriacetic acid, maleic acid, oxalate, polyacrylic acid, sodium, potassium, calcium, or magnesium ions. 
     In still other embodiments, the gel may be removed by drawing the gel out of the calyx using a lumen of the viewing device or a separate catheter. 
     Although the marking material  36  may, in some cases, naturally degrade and be excreted over time, the marking material will remain in place for at least the duration of the inspection procedure. Therefore, as the surgeon moves on to other calices  16  (or other cavities), the marking material  36  will continue to provide a visual marker of where the surgeon has already been. 
     Referring now to  FIG. 2C , the surgeon has manipulated the viewing device  30  such that it is positioned for insertion into a second calyx  38  (which extends into the page in  FIG. 2C ). Assuming that the second calyx  38  comprises a stone (not visible in  FIG. 2C ), the surgeon can identify the stone using the viewing device  30 , and then remove it. Referring to  FIG. 2D , the surgeon has removed the stone  40  using a retrieval device  42 . By way of example, the retrieval device  42  is inserted through a working channel of the viewing device  30 . In such a case, the retrieval device  42  and the viewing device  30  can be withdrawn from the body together (e.g., via the access sheath  32 ) to remove the stone  40 . Alternatively, the retrieval device  42  can be inserted into the kidney  10  separate from the viewing device  30 . 
     After the stone  40  has been removed, and assuming no other stones exist in the second calyx  38 , the calyx can be marked with the marking material  36  in similar manner to that described above in relation to the first calyx  34 . Accordingly, the second calyx  38  can, for example, be filled with the marking material  36  as is indicated in  FIG. 2E . Again, such filling can be accomplished using a working or irrigation channel of the viewing device  30 , a separate catheter, or a percutaneous injection device. 
     The above-described process can continue in similar manner until every calyx  16  has been inspected, all stones have been removed, and all inspected calices have been marked. In such a case, the surgeon can readily determine that each calyx has been inspected. In cases in which the marking material  36  comprises a gel, a further benefit is provided if lithotripsy is performed. Specifically, once a calyx  16 , or its entrance, has been filled with a gel-based marking material, fragments that break off of a stone during lithotripsy will not be able to enter the calyx. Therefore, the surgeon need not recheck previously-inspected calices after lithotripsy. 
       FIGS. 3A and 3B  illustrate an example of a further marking application. Beginning with  FIG. 3A , a given calyx  44  comprises a plurality of stones  46  that are to be removed. By way of example, the stones  46  comprise fragments of a larger stone that was broken up through lithotripsy. Assuming that the surgeon can only remove one stone  46  at a time, or at least cannot remove all of the stones at once, the surgeon may need to return to the calyx  44  one or more times after withdrawing the viewing device  30 . In such a case, it may be difficult for the surgeon to relocate the calyx  44  or distinguish it from other calices  16  of the kidney  10 . To aid the surgeon in such relocation, the surgeon can mark the calyx  44  with the marking material  36 , as is indicated in  FIG. 3A . After marking the calyx  44 , the surgeon can then remove the stones  46  (e.g., one by one) from the calyx through the marking material  36  using the retrieval device  42 . In cases in which the marking material  36  is a gel, the marking material will stay in place despite the insertion and withdrawal of the viewing device  30  and/or retrieval device  42 . 
       FIG. 4  illustrates a further marking application. In this application, several of the calices  48  have been marked with a first marking material  50  to indicate a first condition, and one calyx  52  has been marked with a second marking material  54  to indicated a second condition. In this example, the first condition is absence of any stones and the second condition is presence of one or more stones  56 . The marking material  50  is distinguishable from the marking material  54  in one or more ways. In some embodiments, the marking material  50  comprises a different colored dye than the marking material  54  comprises. In such a case, the surgeon can distinguish the two types of calices (e.g., those containing stones and those not containing stones) using the viewing device  30 . In addition or exception, the marking material  50  comprises a different concentration of contrast agent than the marking material  54 . In such a case, the surgeon can distinguish the two types of calices from a fluoroscopic image. 
     As is indicated in  FIG. 4 , each of the calices  48  extends from a major calyx  58 . In such a case, in which the cavities to be marked comprise all of the cavities of a given group or branch of cavities, the entire calyx  58  can be filled with the marking material  50  to indicate that that entire portion of the kidney  10  has already been inspected.