Abstract:
A method of determining information regarding an implanted medical device. The method includes scanning an infrared or near-infrared laser over a target area wherein a medical device having at least one light affective area defined thereon is implanted; sensing reflected light from the scanned area; processing the reflected light and creating an image which indicates the light affective area based on a difference in the sensed light; and displaying the created image. A system for determining information regarding an implanted medical device is also provided.

Description:
[0001]    This application claims the benefit of U.S. Provisional Appln. No. 61/935,527, filed Feb. 4, 2014, the contents of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates generally to medical devices, and more particularly to location and identification of implanted medical devices utilizing a light based system. 
       BACKGROUND OF THE INVENTION 
       [0003]    Implantable medical devices are devices which are implanted subcutaneously and provide a biological function for the patient. Such implantable medical devices include, for example, screws, pins, plates, pods, artificial joints, coronary stents, cardioverter defibrillators, heart pacemakers, IUDs (Intra-Uterine Devices), catheters and venous access ports. 
         [0004]    After implantation, and sometimes during the implantation procedure, it is necessary to locate the position and/or orientation of the implanted medical device and also to confirm or determine the attributes of the medical device. In many situations, the subcutaneous device is not visible, and therefore, other techniques must be utilized to determine the location, orientation or attributes of the medical device. Exemplary techniques include palpation, i.e. feeling for the device, and x-ray imaging. 
         [0005]    While these techniques have met some needs, each also has drawbacks. In one exemplary application, namely a venous access port, palpation requires the practitioner to feel for the subcutaneous port within a fat layer of the patient. In some instances, the practitioner may feel some other hardened object and mistakenly identify it as the port. Additionally, even if the port is located, the practitioner may have difficulty specifically locating the septum portion of the port and several needle sticks in the general area may be necessary. Alternatively, the practitioner may correctly locate the port, however, if the port has rotated such that the septum is not partially or completely available, the practitioner may not be able to determine such until after several needle sticks. While x-ray imaging provides a more precise view of the subcutaneous port, it may have its own drawbacks. Firstly, x-ray imagining typically requires the patient to be transported to a specific x-ray imagining location, which delays the procedure and requires additional resources. Additionally, each x-ray procedure exposes the patient to additional radiation, which generally is desired to be kept to a minimum. 
         [0006]    It is desired to provide a system and method that provides a medical practitioner with capability to discern one or more properties of an implantable medical device. 
       SUMMARY OF THE INVENTION 
       [0007]    In at least one embodiment, the present invention provides a method of determining information regarding an implanted medical device. The method includes scanning an infrared or near-infrared light over a target area wherein a medical device having at least one light affective area defined thereon is implanted. By light affective area, it is meant that the area affects light more by having a greater absorption or reflection effect on infrared or near-infrared light then surrounding areas. The method further includes receiving reflected light from the scanned area or sensing the absorbed light; processing the reflected or absorbed light and creating an image which indicates the light affective area based on a difference in the received reflected or absorbed light; and displaying the created image. 
         [0008]    In at least one embodiment, the step of displaying the created image includes projecting the created image as visible light on the target area. 
         [0009]    In at least one embodiment, the information to be determined includes one of location, orientation or attribute of the medical device. 
         [0010]    In at least one embodiment, the invention provides a system for determining information regarding an implanted medical device. The system includes a medical device having at least one light affective area defined thereon; and a light sensing device. The light sensing device is configured to scan a target area with an infrared or near-infrared light; receive reflected light or sense absorbed light from the target area; and create an image which indicates the light affective area based on a difference in the received reflective or absorbed light. 
         [0011]    In at least one embodiment, the invention provides a venous access port including a body defining an internal reservoir in communication with a discharge port; a septum positioned above the internal reservoir; and at least one light affective area configured to identify the location of the septum, the at least one light affective area absorbs or reflects infrared or near-infrared light differently than the remainder of the body. In one embodiment, the at least one light affective area is defined about the septum. In yet another embodiment, the at least one light affective area is defined by the septum. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate the presently preferred embodiments of the invention, and, together with the general description given above and the detailed description given below, serve to explain the features of the invention. In the drawings: 
           [0013]      FIG. 1  is a perspective view illustrating use of a light scanning device to visualize an implanted exemplary venous access port in accordance with an exemplary embodiment of the invention. 
           [0014]      FIG. 2  is a perspective view illustrating use of a light scanning device to visualize an implanted exemplary catheter in accordance with an exemplary embodiment of the invention. 
           [0015]      FIG. 3  is a perspective view of one embodiment of a venous access port useable in accordance with the present invention. 
           [0016]      FIG. 4  is a top plan view of the port of  FIG. 3 . 
           [0017]      FIG. 5  is a bottom plan view of the port of  FIG. 3 . 
           [0018]      FIG. 6  is a cross-sectional view along the line  6 - 6  in  FIG. 4 . 
           [0019]      FIG. 7  is a cross-sectional view along the line  7 - 7  in  FIG. 4 . 
           [0020]      FIG. 8  is a top plan view similar to  FIG. 4  illustrating an alternatively marked port. 
           [0021]      FIG. 9  is a top plan view of an alternative venous access port useable in accordance with the present invention. 
           [0022]      FIG. 10  is a cross-sectional view along the line  10 - 10  in  FIG. 9 . 
           [0023]      FIG. 11  is a bottom plan view of the port of  FIG. 9 . 
           [0024]      FIG. 12  is an illustrative image of the light detected by the light scanning device as applied to the port of  FIG. 3 . 
           [0025]      FIG. 13  is an illustrative projected image from the light scanning device based upon the light detected as illustrated in  FIG. 12 . 
           [0026]      FIG. 14  is an alternative projected image from the light scanning device based upon light detected from the port of  FIG. 8 . 
           [0027]      FIG. 15  is an alternative projected image from the light scanning device based upon light detected from an alternative venous access port. 
           [0028]      FIG. 16  is an alternative projected image from the light scanning device based upon light detected from the port of  FIG. 9 . 
           [0029]      FIGS. 17 and 18  are illustrative projected images from the light scanning device based upon light detected from the catheter of  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0030]    In the drawings, like numerals indicate like elements throughout. Certain terminology is used herein for convenience only and is not to be taken as a limitation on the present invention. The following describes preferred embodiments of the present invention. However, it should be understood, based on this disclosure, that the invention is not limited by the preferred embodiments described herein. 
         [0031]    Referring to  FIGS. 1 and 2 , an exemplary light scanning device  20  is illustrated in use to detect an implanted medical device, i.e. a venous access port  50  in  FIG. 1  and a catheter  150  in  FIG. 2 . The exemplary light scanning device  20  uses a two-axis optical scanner to sweep an infrared (IR) or near-infrared (NIR) laser  22  over a target area  12  of a patient  10 . The sweeping laser  22  defines a two-dimensional field of view  24 . As explained in more detail hereinafter, the implanted medical device  50 ,  150  is formed with at least one light affective area which is configured to affect the IR or NIR light differently compared to the surrounding tissue and the remaining components of the medical device  50 ,  150 . For example, the medical device  50 ,  150  may have an area configured to absorb the IR or NIR light, such that less of the light is reflected in that area or an area configured to reflect the IR or NIR light, such that more of the light is reflected in the area compared to surrounding areas. 
         [0032]    At the same time, the light scanning device  20  is configured to receive and record the reflected light from the field of view  24  using photodiodes or the like tuned to the wavelength of the laser  22 . The light sensing device  20  includes a processor (not shown) which receives signals corresponding to the received reflected light and utilizes digital signal processing or the like to create an image of the sensed field of view. The light sensing device  20  may include a display  28  upon which the image is displayed. Additionally, the light sensing device  20  is further configured to reproject the created image onto the skin using a visible laser. In an exemplary embodiment, the IR or NIR laser  22  has a wavelength of approximately 785 nm and the visible laser has a wavelength of approximately 642 nm. Aligned with the data acquired in the infrared range, the projected image provides the practitioner with direct and immediate feedback on the location and orientation of the implanted medical device  50 ,  150 . 
         [0033]    The light scanning device  20  may have various internal components for generating and detecting the IR or NIR light and for generating the projected image using visible light. Additionally, the light scanning device  20  may be a stationary device or a portable device. Various systems for carrying out such light sensing and image generation are set forth in U.S. Pat. Nos. 8,073,531; 8,255,040; 8,295,904; 8,328,368; 8,380,291; 8,391,960; 8,463,364; 8,478,386; 8,489,178; and 8,594,770, each of which is incorporated herein by reference. 
         [0034]    As set forth above, the medical devices  50 ,  150  are preferably formed with at least one light affective area which is configured to interact differently with the IR or NIR light compared to the surrounding tissue and the remaining components of the medical device  50 ,  150 . Exemplary venous access ports  50  incorporating such a light affective area will be described with reference to  FIGS. 3-11 . 
         [0035]    Referring to  FIGS. 3-7 , a first exemplary venous access port  50  will be described. The port  50  generally has a structure similar to the port structure disclosed in U.S. Pat. No. 8,257,325, the contents of which are incorporated herein by reference. Generally, the venous access port  50  includes a housing  52  and a septum  54 , with a discharge port  56  extending from a distal end  58  of the port assembly  50  to be attached securely and sealingly to the proximal end of a catheter (not shown). A passageway  60  extends from the interior reservoir  62  to the distal tip opening  64  of discharge port  56 . 
         [0036]    With reference now to  FIGS. 6 and 7 , the interior of the port assembly  50  is shown to provide an interior reservoir  62 . The housing  52  is shown to include a housing base  68  of needle-impenetrable material that includes a well  70  having a bottom floor  72  and side walls  74  that define the interior reservoir  62  beneath septum  54 . A skirt  82  is overmolded about housing base  68  and may be of silicone elastomer or other biocompatible material. A cap  88  is also secured to housing base  68  to in turn secure the septum  54  in position in the port assembly  50 . The housing base  68  includes a septum seat  92  extending into the top of well  70 , into which a flange of the septum will be seated. 
         [0037]    Referring to  FIGS. 3 and 4 , the cap  88  defines a series of light affective areas  91 ,  93  annularly about the septum  54 . With this illustrative port  50 , four darker absorptive areas  91  alternate with four lighter absorptive areas  93 . The darker absorptive areas  91  are configured to absorb more of the IR or NIR light  22  such that less reflected light will be received for these areas while the lighter absorptive areas  93  are configured to absorb less of the IR or NIR laser  22  light such that more reflected light will be received for these areas. 
         [0038]    The light affective areas  91 ,  93  may be defined utilizing various techniques. As examples, the light affective areas  91 ,  93  may be defined to have a color which is absorptively or reflectively distinct from the other areas and other components. Alternatively, materials having different IR or NIR absorptive or reflective qualities may be selected. For example, all or portions of the cap  88  may be made from absorptively or reflectively distinct material. In another embodiment, the septum  54  itself may be manufactured from an absorptively or reflectively distinct material such that the septum defines the light affective area and appears as a distinctly lighted area of the reprojected image  26 . As another exemplary alternative, the light affective areas  91 ,  93  may be defined by coating the areas with materials which are absorptively or reflectively distinct, e.g. materials having different fluorescence. As yet another exemplary alternative, the light affective areas  91 ,  93  may have varying configurations, e.g. different concavities or convexities, which cause absorptively or reflectively distinct areas. Other mechanisms, for example, light producing LEDs or light reflective metals, coatings or the like, may be positioned in the light affective areas  91 ,  93 . The invention is not limited to these exemplary mechanisms for achieving absorptively or reflectively distinct areas and other mechanisms may be utilized. 
         [0039]    The received reflected light for this embodiment of the port  50  is illustrated in  FIG. 12 , with the areas corresponding to the darker absorptive areas  91  appearing darker than the areas corresponding to the lighter absorptive areas  93 . While this embodiment is described with the light affective areas  91 ,  93  as absorptive areas, it is recognized that one or both of the areas may instead be reflective areas. As illustrated, each of the light affective areas  91 ,  93  is distinct from the surrounding area and the remainder of the port  50 , including the septum  54 . In this way, the septum  54  is clearly identifiable as it is encircled by the light affective areas  91  and  93 . 
         [0040]      FIG. 13  illustrates an exemplary reprojected visible image  26  based on the light received as illustrated in  FIG. 12 . The light sensing device  20  is preferably configured to process the received signals such that the reprojected visible image  26  corresponds to the received light, but is sharper and clearer at the contrasting areas. As seen, the reprojected image  26  will allow the practitioner to clearly identify the location of the port  50 , but more specifically the target septum  54 . The practitioner can easily insert a needle into the septum  54  without the need to guess its exact location as may be required using the palpation technique. Additionally, the sensed light and projected image  26  allow the practitioner to easily determine the orientation of the port  50 . If the port  50  began to turn in the patient, the practitioner would see such change in orientation and corrective measures may be initiated more promptly than with prior techniques. 
         [0041]    The light affective areas  91 ,  93  may also be utilized to provide attributes of the medical device. For example, the port  50  of  FIGS. 3-7  is a power injectable port and the pattern of the light affective areas  91 ,  93  (e.g. four alternating areas) may be configured to convey that the port  50  is power injectable. Contrast this to the port  50 ′ illustrated in  FIG. 8  which is generally the same as the port  50 , but which is not power injectable. The cap  88 ′ includes a series of light affective areas  91 ′ and  93 ′ about the septum  54 , however, only three of each light affective area  91 ′,  93 ′ are provided. A standard may be set such that the alternating pattern of three light affective areas  91 ′,  93 ′ corresponds to a non-power injectable port  50 ′. Comparing the reprojected visible image  26 ′ of the port  50 ′ in  FIG. 14  with the image  26  of the port  50  in  FIG. 13 , it would be clear to the practitioner which port is power injectable and which is not. As an alternative, the non-power ports may be made without any absorptive/reflective pattern that by its very absence would be clear to the practitioner that the port is non-power injectable. 
         [0042]    As illustrated in  FIG. 5 , the port  50  may still include radiopaque markings  100  to designate the port  50  as power injectable. A larger outer circle  102  is seen provided on the outermost periphery of bottom base surface  94  and a smaller inner circle  104  is seen provided more centrally. The outer and inner circles or rings  102 ,  104  circumscribe radiopaque indicia  110 . Other radiopaque markings  100  distinct from the elements shown may also be utilized. Inclusion of the radiopaque markings  100  in addition to the light affective areas  91 ,  93  allows the attributes of the port  50  to be identified in the event a light sensing device  20  is not available or in the event that the patient is undergoing an x-ray anyway. 
         [0043]    Referring to  FIG. 15 , the location/orientation function may be distinct from the attribute identification function. For example, the reprojected image  26 ″ represents a power injectable port  50 ″ in which a single light affective area  91 ″ encircles the septum  54  to provide an indication of the location and orientation of the septum  54 . A second light affective area  95  in the form of an alphanumeric indicia, i.e. “CT”, is defined in the middle of the septum  54  and is visible in the reprojected image  26 ″. Other standards may be utilized be to convey attribute information. Also, additional attribute information other than the power injectability may be incorporated into the information represented by the light affective areas. 
         [0044]    Referring to  FIGS. 9-11  and  16 , another exemplary port  50 ′″ will be described. The port  50 ′″ is similar to the previous embodiments, but provides a dual port with a pair of septums  54 ,  54 ′ positioned over respective reservoirs  62 ,  62 ′. A respective passageway  60 ,  60 ′ extends from each interior reservoir  62 ,  62 ′ to the distal tip openings of discharge port  56 . As illustrated in  FIG. 9 , a series of light affective areas  91 ,  92  may be provided about each septum  54 ,  54 ′ such that the two distinct target areas will be visible in the reprojected image  26 ″, as illustrated in  FIG. 16 . 
         [0045]    Referring to FIGS.  2  and  17 - 18 , use of the light sensing device with an alternative implantable medical device, namely, a catheter  150 , will be described. In the illustrated embodiment, a light affective area  191  is defined at the tip  152  of the catheter tube  154 . The light affective area  191  is similar to the light affective areas described above. While the illustrated embodiment includes light affective area  191  only at the tip  152 , it may be provided over a larger area, at spaced intervals or any other desired configuration. As illustrated in  FIG. 17 , the reprojected image  26   iv  will show the position of the tip  152  as the catheter body  154  is advanced through an incision  155  and under the skin of the patient. Additionally or alternatively, the configuration of the light affective area  191  may be selected such that it is absorptively or reflectively distinct from a fluid  160  intended to be passed through the catheter  150  such that both the tip  152  and the presence of the fluid  160  in the catheter are visible on the reprojected image  26   v , as illustrated in  FIG. 18 . 
         [0046]    While the present invention has been described with respect to various venous access ports and catheters, the invention is not limited to such and other medical devices may be formed with light affective areas and a light scanning device may be utilized to determine location, orientation, attributes and other information about the subcutaneously implanted medical devices. 
         [0047]    These and other advantages of the present invention will be apparent to those skilled in the art from the foregoing specification. Accordingly, it will be recognized by those skilled in the art that changes or modifications may be made to the above-described embodiments without departing from the broad inventive concepts of the invention. It should therefore be understood that this invention is not limited to the particular embodiments described herein, but is intended to include all changes and modifications that are within the scope and spirit of the invention as defined in the claims.