Abstract:
Embodiments of the invention provide a system and method for resecting a tissue mass. The system for resecting a tissue mass includes a surgical instrument and a first sensor for measuring a signal corresponding to the position and orientation of the tissue mass. The first sensor is dimensioned to fit inside or next to the tissue mass. The system also includes a second sensor attacked to the surgical instrument configured to measure the position and orientation of the surgical instrument. The second sensor is configured to receive the signal from the first sensor. A controller is in communication with the first sensor and/or the second sensor, and the controller executes a stored program to calculate a distance between the first sensor and the second sensor. Accordingly, visual, auditory, haptic or other feedback is provided to the clinician to guide the surgical instrument to the surgical margin.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of the filing date of U.S. provisional patent application Ser. No. 61/874,675 entitled “SYSTEM AND METHOD FOR A TISSUE RESECTION MARGIN MEASUREMENT DEVICE” filed Sep. 6, 2013, the entire contents of which are incorporated by reference herein for all purposes. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Minimally invasive surgical resection of tumors involves the precise excision of the tumor while sparing surrounding healthy and critical tissue. Some examples include, but are not limited to, breast conserving surgery and Video-assisted Thoracic Surgery (VATS). Surgical resection of the tumor requires the removal of a margin of tissue around the tumor to ensure complete removal of the tumor cells and improved long-term survival. The default margin is dependent on the type of tumor and micro-invasion of the tumor into the surrounding tissue. Significant deformation of the tissue due to high viscoelasticity or physiological motion (such as collapsing of the lung) can lead to difficulty in localizing the tumor and precise removal of the tumor. As a result, this can lead to tumor recurrence and poor long-term benefits. Two surgical applications are listed below as an example. However, the disclosed system and method may be applied for resection or biopsy of other lesions through a minimally invasive approach or open-surgery. 
         [0003]    Current clinical practice to remove lung tissue segments involves opening the chest by cutting the sternum or by spreading the ribs. Many times ribs are broken and often segments are surgically removed during these procedures. The orthopedic trauma alone presents considerable pain and it can complicate the recovery process with patients. Thoracic pain of this magnitude also complicates the task of recovering a patient from general anesthesia since the body acclimates to forced ventilation and the pain can interrupt natural chest rhythm. Patients benefit dramatically from procedures that are performed through small incisions or ports in the chest without causing this orthopedic trauma. 
         [0004]    Relatively few thoracic procedures are currently performed using minimally invasive or VATS techniques even though they are well known to provide benefit to the patient by minimizing trauma and speeding recovery times compared to open chest procedures. This is due, at least in part, to the fact that there are only a few available instruments designed specifically to enable thoracic procedures in this way. 
         [0005]    Surgery for lung cancer, however, is moving to a minimally invasive approach using VATS and smaller non-anatomic lung resection (i.e., wedge resection) particularly for small lesions. In the conventional method of performing VATS, however, the lung is collapsed leading to difficulty in precisely locating the tumor and determining the resection margins. Additionally, palpation of lung tissue is not possible due to the minimally invasive approach to surgery. Imprecise surgical resection could lead to subsequent tumor recurrence, stressing a critical structure and possibly rupturing the tissue. 
         [0006]    Breast conserving surgery (BCS) involves the removal of the tumor while sparing the healthy breast parenchyma around the tumor. Studies have shown that BCS combined with chemotherapy has similar long-term benefits as mastectomy with the additional cosmetic advantage. However, identifying and resecting the entire tumor is a challenging task due to the highly deformable nature of the breast. Achieving the negative surgical margin with minimal damage to the healthy parenchyma is non-trivial due to the soft-tissue nature of the breast. 
         [0007]    Therefore, a tissue resection margin measuring device is needed that overcomes the above limitations. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention relates to a system and method for resecting a tissue mass while compensating for tissue deformation due to its elastic nature and physiologically induced motion. In a non-limiting example, the invention enables minimally invasive surgical procedures by providing a device and method to perform tissue resection that discriminates against traumatizing critical tissue and precisely determines the resection margin. Additionally, auditory, visual and haptic cues may be provided to the surgeon to identify and more precisely measure the tumor margins to ensure complete resection of the tumor. 
         [0009]    Some embodiments of the invention provide a system for resecting a tissue mass. The system includes a surgical instrument and a first sensor for measuring a first signal. The first sensor is dimensioned to fit inside or next to the tissue mass. The system also includes a second sensor for measuring a second signal, and the second sensor is coupled to the surgical instrument. A controller is in communication with the first sensor and the second sensor, and the controller executes a stored program to calculate a distance between the first sensor and the second sensor based on the first signal and the second signal. 
         [0010]    In some embodiments the system may further include a sleeve dimensioned to engage at least one of a housing of the surgical device and the second sensor. The second sensor may be coupled to the housing of the surgical instrument by an adhesive, for example. The surgical device may be, for example, a stapler, a Bovi pencil or a cutting device configured to cut along a resection margin surrounding the tissue mass, which may be a tumor, a nodule, or a lesion, for example. The resection margin may be included within the distance calculated between the first sensor and the second sensor. 
         [0011]    In other embodiments, the first signal received by the first sensor can indicate a position and an orientation of the tissue mass relative to the surgical instrument in real time. Similarly, the second signal received by the second sensor can indicate a position and an orientation of the surgical instrument relative to the tissue mass. In one embodiment, the second sensor indicates a position and an orientation of the surgical instrument in the same reference as the first sensor. The first sensor may be a fiducial marker embedded within an anchor made from supereleastic material, and the second sensor may be an instrument sensor. In one embodiment, the first sensor may be configured to measure a position and an orientation of the tissue mass, and the second sensor may be configured to measure a position and an orientation of the surgical instrument. 
         [0012]    In one embodiment, the system may further include a third sensor for measuring a third signal. The third sensor may be dimensioned to fit next to the tissue mass at a position opposite the first sensor, such that the third signal received by the third sensor indicates a position and an orientation of the tissue mass relative to the first sensor. 
         [0013]    In other embodiments, the first sensor may be embedded within a hook structure. The hook structure may be in the form of a T-bar and dimensioned to fit inside a delivery needle and/or a sheath. The delivery needle and/or the sheath may be configured to guide the first sensor, and the hook structure may be configured to anchor the first sensor within the tissue mass. In one embodiment, the first sensor that is embedded within the hook structure may be inserted into the tissue mass under real time image guidance. 
         [0014]    In an alternative embodiment, the first sensor is embedded within a hook structure that includes a plurality of prongs, and the first sensor may be dimensioned to fit inside a delivery needle and/or a sheath. The delivery needle and/or the sheath may be configured to guide the first sensor, and the plurality of prongs may be configured to anchor the first sensor within the tissue mass. The hook structure may further comprise a plurality of extensions extending from a tube portion of the hook structure, such that the plurality of extensions may be dimensioned to receive the first sensor. 
         [0015]    The system may further include a display in communication with the controller. The display may be coupled to the surgical instrument and configured to display the distance calculated by the stored program executed by the controller. The display may be, but is not limited to, an OLED display or an LCD display. In other embodiments, the system may include an audible source for emitting an audible signal. The audible source may be in communication with the controller, which is configured to execute a stored program to alter the audible signal based on the distance between the first sensor and the second sensor. In one embodiment, the stored program is a navigation system. 
         [0016]    The system may further include a piezoelectric actuator coupled to a handle of the surgical instrument. The piezoelectric actuator may be configured to emit a haptic signal. The piezoelectric actuator may be in communication with the controller, which is configured to execute a stored program to alter the haptic signal based on the distance between the first sensor and the second sensor. 
         [0017]    The system may further include a monitor for emitting a visual signal in some embodiments. The monitor may be in communication with the controller, the which is configured to execute a stored program to alter the visual signal based on the distance between the first sensor and the second sensor. Additionally or alternatively, the system may include a monitor for displaying a video overlay. The monitor may be in communication with the controller, which is configured to execute a stored program to fuse a laparoscopy image to a virtual endoscopy image to create the video overlay. The video overlay may be configured to identify a position of the tissue mass and the first sensor. 
         [0018]    In another embodiment, the invention provides a method for resection of a tissue mass inside a patient. The method includes inserting a first sensor inside or next to the tissue mass and capturing at least one image of the first sensor embedded within or next to the tissue mass. A resection margin is calculated around the tissue mass using the at least one image. A surgical instrument inserted into the patient, and the surgical instrument is coupled to a second sensor. The second sensor is tracked relative to the resection margin, and the surgical instrument is used to cut on the resection margin. 
         [0019]    In some embodiments the method may further include dimensioning a sleeve to engage at least one of a housing of the surgical device and the second sensor. The second sensor may be coupled to the housing of the surgical instrument by an adhesive, for example. The surgical device may be, for example, a stapler, a Bovi pencil or a cutting device configured to cut along a resection margin surrounding the tissue mass, which may be a tumor, a nodule, or a lesion, for example. The resection margin may be included within the distance calculated between the first sensor and the second sensor. 
         [0020]    In other embodiments, the first signal received by the first sensor can indicate a position and an orientation of the tissue mass relative to the surgical instrument in real time. Similarly, the second signal received by the second sensor can indicate a position and an orientation of the surgical instrument relative to the tissue mass. In one embodiment, the second sensor indicates a position and an orientation of the surgical instrument in the same reference as the first sensor. The first sensor may be a fiducial marker constructed from a supereleastic material, and the second sensor may be an instrument sensor. In one embodiment, the first sensor may be configured to measure a position and an orientation of the tissue mass, and the second sensor may be configured to measure a position and an orientation of the surgical instrument. 
         [0021]    In one embodiment, the method may further include providing a third sensor for measuring a third signal. The third sensor may be dimensioned to fit next to the tissue mass at a position opposite the first sensor, such that the third signal received by the third sensor indicates a position and an orientation of the tissue mass relative to the first sensor. 
         [0022]    In other embodiments, the first sensor may embedded within a hook structure. The hook structure may be in the form of a T-bar and dimensioned to fit inside a delivery needle and/or a sheath. The delivery needle and/or the sheath may be configured to guide the first sensor, and the hook structure may be configured to anchor the first sensor within the tissue mass. In one embodiment, the first sensor that is embedded within the hook structure may be inserted into the tissue mass under real time image guidance. 
         [0023]    In an alternative embodiment, the first sensor is embedded within a hook structure that includes a plurality of prongs, and the first sensor may be dimensioned to fit inside a delivery needle and/or a sheath. The delivery needle and/or the sheath may be configured to guide the first sensor, and the plurality of prongs may be configured to anchor the first sensor within the tissue mass. The hook structure may further comprise a plurality of extensions extending from a tube portion of the hook structure, such that the plurality of extensions may be dimensioned to receive the first sensor. 
         [0024]    The method may further include providing a display in communication with a controller. The display may be coupled to the surgical instrument and configured to display the distance calculated by the stored program executed by the controller. The display may be, but is not limited to, an OLED display or an LCD display. In other embodiments, the method may include emitting an audible signal from an audible source. The audible source may be in communication with the controller, which is configured to execute a stored program to alter the audible signal based on the distance between the first sensor and the second sensor. In one embodiment, the stored program is a navigation method. 
         [0025]    The method may further include emitting a haptic signal from a piezoelectric actuator coupled to a handle of the surgical instrument. The piezoelectric actuator may be in communication with the controller, which is configured to execute a stored program to alter the haptic signal based on the distance between the first sensor and the second sensor. 
         [0026]    In some embodiments, the method may further include emitting a visual signal on a monitor. The monitor may be in communication with the controller, the which is configured to execute a stored program to alter the visual signal based on the distance between the first sensor and the second sensor. Additionally or alternatively, the method may include displaying a video overlay on the monitor. The monitor may be in communication with the controller, which is configured to execute a stored program to fuse a laparoscopy image to a virtual endoscopy image to create the video overlay. The video overlay may be configured to identify a position of the tissue mass and the first sensor. 
         [0027]    These and other features, aspects, and advantages of the present invention will become better understood upon consideration of the following detailed description, drawings, and appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]      FIGS. 1A  is a perspective view of an example fiducial sensor being deployed through a delivery needle according to one embodiment of the present invention. 
           [0029]      FIG. 1B  is a perspective view of the example fiducial sensor of  FIG. 1A  being deployed through the delivery needle next to a tissue mass according to one embodiment of the present invention. 
           [0030]      FIG. 1C  is a perspective view of an additional fiducial sensor and the example fiducial sensor of  FIG. 1A  being deployed through the delivery needle next to the tissue mass according to one embodiment of the present invention. 
           [0031]      FIG. 2  is a perspective view of an example fiducial sensor embedded within a hook structure according to another embodiment of the present invention. 
           [0032]      FIG. 3A  is a perspective view of the fiducial sensor embedded in the tissue mass of  FIG. 1B  with a resection margin surrounding the tissue mass. 
           [0033]      FIG. 3B  is a perspective view of the fiducial sensor embedded next to the tissue mass of  FIG. 1B  with the resection margin surrounding the tissue mass. 
           [0034]      FIG. 4  is a partial perspective view of a conventional stapler device used for resecting a tissue mass. 
           [0035]      FIG. 5  is a partial perspective view of the stapler device of  FIG. 4  with a sleeve including an instrument sensor over a housing of the stapler device according to one embodiment of the present invention. 
           [0036]      FIG. 6  is a perspective view of the stapler device of  FIG. 5  inserted into a patient and shows a distance between the fiducial sensor and the instrument sensor. 
           [0037]      FIG. 7A  is an example screenshot of a virtual endoscopy view of the tissue mass overlaid on a laparoscopy view. 
           [0038]      FIG. 7B  is an example screenshot of a laparoscopy view of the tissue mass. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0039]    Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
         [0040]    The following discussion is presented to enable a person skilled in the art to make and use embodiments of the invention. Various modifications to the illustrated embodiments will be readily apparent to those skilled in the art, and the generic principles herein can be applied to other embodiments and applications without departing from embodiments of the invention. Thus, embodiments of the invention are not intended to be limited to embodiments shown, but are to be accorded the widest scope consistent with the principles and features disclosed herein. The following detailed description is to be read with reference to the figures, in which like elements in different figures have like reference numerals. The figures, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of embodiments of the invention. Skilled artisans will recognize the examples provided herein have many useful alternatives and fall within the scope of embodiments of the invention. 
         [0041]      FIGS. 1A-1C  illustrate an example fiducial sensor  10  being inserted through a delivery needle  12 . The fiducial sensor  10  may be, for example a marker that includes a transmitter that measures position and orientation of a tissue mass  18  in real-time. The fiducial sensor  10  may be attached to a cable  14 , as shown in  FIGS. 1A-1C , or the fiducial sensor  10  may be wireless. The fiducial sensor  10  may be embedded within a hook structure  16 , as shown in  FIG. 1A . The hook structure  16  of the fiducial sensor  10  can be made from a superelastic material, for example nitinol or stainless steel, or any other suitable material. This will allow for the fiducial sensor  10  to be inserted through the delivery needle  12  and deployed through an opening  22  (i.e., the lumen) of the delivery needle  12  into the center or the periphery of the tissue mass  18 . The tissue mass  18  may be, for example, a tumor, nodule or lesion. 
         [0042]    As shown in  FIG. 2 , a more detailed view of the fiducial sensor  10  and hook structure  16  is shown. The hook structure  16  may include a tube portion  15  having a plurality of extensions  17  extending from one end of the tube portion  15  and a plurality of prongs  20  extending from an opposing end of the tube portion  15 . The tube portion  15  may be, for example, a nitinol tube having an outer diameter D 1  between about 0.6 millimeters and about 0.8 millimeters, and the hook structure  16  may have an overall length L between about 8 millimeters and about 12 millimeters. The tube portion  15  may be laser micro-machined into a cylindrical shape having the plurality of extensions  17  extending therefrom to secure the fiducial sensor  10  in place. In some embodiments, the fiducial sensor  10  may be an electromagnetic sensor that is attached to the proximal end of the hook structure  16  using a medical grade epoxy adhesive, such as AA-Bond FDA 22 . 
         [0043]    The plurality of prongs  20 , as shown in  FIG. 2 , may be configured to anchor the hook structure  16 , including the fiducial sensor  10 , into a tissue mass, such as the tissue mass  18  of  FIG. 1B . The plurality of prongs  20  may be constructed from a superelastic shape memory alloy, such as nitinol. The plurality of prongs  20  may be bent, for example, and extend outwardly from a central axis Y of the hook structure  16 . The plurality of prongs  20  may also be heat-treated to ensure that the prongs  20  retain the curved shape and the phase structure of the nitinol is in the Martensite phase, for example. In the embodiment shown in  FIG. 2 , the hook structure  16  includes three prongs  20 , however any suitable number of prongs may be provided in order to anchor the hook structure  16  to the tissue mass. 
         [0044]    The fiducial sensor  10  along with the hook structure  16  may be inserted through a distal end of the delivery needle  12 , which may be an 18-gauge needle, for example. The plurality of prongs  20  of the hook structure  16  may be inserted into the lumen  22  of the delivery needle  12  first. Advantageously, due to the superelastic nature of nitinol, the hook structure  16  can be easily inserted into the lumen  22  of the delivery needle  12 . The hook structure  16  may be deployed using a metal stylet (not shown) that is inserted through the lumen  22  of the delivery needle  12 . Upon being completely deployed, the plurality of prongs  20  will regain their original curved shape and open up to firmly anchor the hook structure  16  into the tissue mass  18 . The delivery needle  12  may then be removed after deployment of the hook structure  16 . 
         [0045]    In some embodiments, the fiducial sensor  10  along with the hook structure  16 , may be inserted through the delivery needle  12  under real-time image guidance (i.e., CT, DynaCT, MRI, Ultrasound, etc.) and embedded within the tissue mass  18 , as shown in  FIG. 3A , or next to the tissue mass  18 , as shown in  FIG. 3B . The fiducial sensor  10  may be embedded within or next to the tissue mass  18  before or during a surgical procedure. By using real-time image guidance, the spatial relationship (i.e., position and orientation) of the fiducial sensor  10  to the tissue mass  18  in three dimensions is known at all times. The hook structure  16  may be in the form of a T-bar, for example, to anchor the fiducial sensor  10  within or next to the tissue mass  18  to inhibit migration. Advantageously, the force is at the center of the T-bar  16  due to the wire  14 , thereby facilitating anchoring the fiducial sensor  10  next to the tissue mass  18 . The fiducial sensor  10  embedded within or next to the tissue mass  18  will measure the position and orientation of the tissue mass  18  in real-time in spite of any deformation introduced due to soft tissue deformation or physiological motion such as collapsing of the lung or respiration, for example. Thereby easily identifying the location of the tissue mass  18  that is often difficult to determine. 
         [0046]    In an alternative embodiment, shown in  FIG. 1C , a second fiducial sensor  11  in the form of a T-bar, for example, may be put in a different location near the tissue mass  18 . The second fiducial sensor  11  may have a separate cable  14  from the first fiducial sensor  10 , as shown in  FIG. 1C , or the first fiducial sensor  10  and the second fiducial sensor  11  may share the same cable  14 . The second fiducial sensor  11 , or any other such device, can be used to improve the localization of the tissue mass  18 , even when there may be deformation. For example, the second fiducial sensor  11  can be placed on the opposite side of the tissue mass  18  from the first fiducial sensor  10  and be recognized by the first fiducial sensor  10  through distortions in the Electromagnetic field. Therefore, by knowing that the tissue mass  18  is between these two sensors, the tissue mass  18  can be localized despite changes in the soft tissue. 
         [0047]    Referring now to  FIGS. 3A and 3B , once the position and orientation of the tissue mass  18  is known, a resection margin  24  having a predetermined distance D 2  surrounding the tissue mass  18  is determined by creating a three dimensional envelope around the tissue mass  18 . The resection margin  24  may be manually set to the desired predetermined distance D 2 , for example two centimeters. The predetermined distance D 2  defines a threshold value so when a surgical device  26 , described in further detail below, is in a position less than the threshold value auditory, visual and/or haptic cues may be provided to the surgeon or the surgical device  26  to ensure precise and complete resection of the tissue mass  18 . 
         [0048]    Referring now to  FIG. 4 , a conventional surgical device  26 , such as a surgical stapler, Bovi pencil, kitner laparoscope and/or any suitable cutting, resecting or ablating device, is shown. The surgical device  26  may include a handle  30  coupled to a fastening assembly  32  at an opposite end of the surgical device  26 . The fastening assembly  32  may be a single-use component that is removably connected to the handle  30 . That is, the fastening assembly  32  may be a cartridge that connects to the handle  30  and is removed after use. The fastening assembly  32  includes a housing  34  that contains a plurality of fasteners  36  that are secured to the tissue during resection of the tissue mass  18 . The fastening assembly  32  may also include a blade slot  38  that accommodates a blade (not shown) for cutting along the resection margin  24  of the tissue mass  18 . 
         [0049]    In a preferred embodiment, the surgical device  26  includes a sleeve  40  that is dimensioned to slide over the housing  34 , for example, as shown in  FIG. 5 . The sleeve  40  may be any commercially available sleeve, for example, that is configured to go over the housing  34  of the surgical device  26 . An instrument sensor  28  may be attached, by stitching for example, to the sleeve  40 . Alternatively, the instrument sensor  28  may be attached directly to the housing  34  of the surgical device  26  via any suitable adhesive or integrated within the housing  34  itself. Regardless of where the instrument sensor  28  is attached, either the sleeve  40  or the housing  34 , the instrument sensor  28  can measure the position and orientation of the surgical device  26  in the same imaging reference frame as the fiducial sensor  10  embedded within or next to the tissue mass  18 . In other words, the position of the surgical device  26  may be precisely measured with respect to the fiducial sensor  10  within or next to the tissue mass  18 , as will be described in further detail below. Since both the fiducial sensor  10  and the instrument sensor  28  are measured in the same reference frame, errors introduced due to the registration and calibration steps, requiring a change of reference axis, can be minimized. 
         [0050]    The sleeve  40  may also include a display  42  that shows the user a distance D 3 , shown in  FIG. 6 , of the surgical device  26  from the resection margin  24 , as will be described below. The display  42  may be attached to the handle  30  of the surgical device  26  and could be any commercially available organic light-emitting diode (OLED) display or liquid-crystal (LCD) display. In the case of an OLED display, a reformatted CT image of the tissue mass  18  located at the tip of the surgical device  26 , for example, may be displayed to the user. 
         [0051]    Referring now to  FIG. 6 , during operation, the fiducial sensor  10  is positioned next to or embedded within the tissue mass  18  using the plurality of prongs  20  of the hook structure  16 , as previously described. A CT/MRI/fluoroscopic examination, for example, is performed to acquire images of the fiducial sensor  10  embedded within the tissue mass  18 . The tissue mass  18  is then segmented from the pre-operative diagnostic CT/MRI examination and a three dimensional model (not shown) of the tissue mass  18  is generated. The intra-operative images obtained during placement of the fiducial sensor  10  may be registered to the patient&#39;s diagnostic exam, and the location of the fiducial sensor  10  may be estimated. As previously discussed, the resection margin  24  having the predetermined distance D 2  surrounding the tissue mass  18  is displayed to the user on a monitor (not shown) as a three dimensional envelope or proximity sphere around the tissue mass  18 . The predetermined distance D 2  of the resection margin  24  may be determined based on the surgeon&#39;s preferences and the type of tissue mass  18 . 
         [0052]    The surgical device  26  is then inserted into a body  44  (i.e., the patient), as shown in  FIG. 6 , to cut the tissue mass  18  along the resection margin  24 . The fiducial sensor  10  embedded within or close to the tissue mass  18  is in electrical or wireless communication with a controller  48 . The controller  48  may be a programmable logic controller (PLC) and is configured to interpret a signal generated by the fiducial sensor  10 . The fiducial sensor  10  may be an electromagnetic sensor, for example, that generates a signal proportional to the position and orientation (e.g., a GPS coordinate) of the fiducial sensor  10 . The signal generated by the fiducial sensor  10  may be for example an electrical signal and the controller  48  may interpret this signal via a stored program  50 . The stored program  50  may include, for example a navigation system that is in communication with the fiducial sensor  10  and the instrument sensor  28 . 
         [0053]    Similarly, the instrument sensor  28  may be an electromagnetic sensor, for example, that generates a signal proportional to the position and orientation (e.g., a GPS coordinate) of the instrument sensor  28 . The signal generated by the instrument sensor  28  may be, for example, an electrical signal and the controller  48  may interpret this signal via a stored program  50 . The fiducial sensor  10  and the instrument sensor  28  communicate with the controller  48  and relay the position and orientation of the tissue mass  18  and the surgical device  26  using the navigation system. In some embodiments, the stored program  50  may be configured to run calibration and/or registration algorithms to track the distal tip of the surgical device  26  and the normal vector to the surgical device  26 . Thereafter, the stored program  50  of the controller  48  calculates the distance D 3 , shown in  FIG. 6 , between the fiducial sensor  10  and the instrument sensor  28  such that when the surgical device  26  is below a threshold value of D 3 , an auditory, visual or haptic cue is generated for the user. 
         [0054]    As the surgical device  26  is navigated towards the resection margin  24  of the tissue mass  18 , the surgical device  26  may excise the tissue mass  18  while minimizing damage to surrounding tissue due to both the fiducial sensor  10  and instrument sensor  28  being actively tracked. Minimal damage to the surrounding healthy tissue may also ensure normal physiological function, for example lung function. Utilizing feedback from the fiducial sensor  10  and the instrument sensor  28  on the surgical device  26 , the distance D 3  from the tissue mass  18  and the surgical device  26  may be known to the user and visible on the display  42  at all times. As a result, the desired resection margin  24  may be maintained at all times, thereby ensuring complete resection of the tissue mass  18 . In an alternative embodiment, the position and orientation data of the tissue mass  18  and the surgical device  26  may lock or unlock the surgical device  26  to inhibit erroneous resection of the tissue mass  18 . 
         [0055]    As described above, auditory, visual and haptic cues may be provided to the surgeon and/or the surgical device  26  to identify the resection margin  24  to ensure precise and complete resection of the tissue mass  18 . For example, an audible source  52  may be configured to emit an audible signal. The audible source  52  may be in communication with the controller 48  that is configured to execute the stored program  50  to alter the audible signal based on the distance D 3  between the instrument sensor  28  and the fiducial sensor  10 . The instrument sensor  28  uses the signal generated by the fiducial sensor  10  to enable the controller  48  to execute the stored program  50  to calculate the distance D 3 , shown in  FIG. 6 , between the fiducial sensor  10  and the instrument sensor  28  such that when the surgical device  26  is below a threshold value of D 3 , the audible signal is generated. The audible signal may be, for example a tone, beep or alarm. The audible signal may also increase in frequency or duty cycle as the distance D 3  decreases, such that as the surgical device  26  is navigated too close to the resection margin  24 , the audible signal&#39;s frequency or duty cycle increases. 
         [0056]    In addition to the auditory cues, visual cues may also be provided to the user on one or more displays  54  in communication with the controller  48 . The one or more displays  54  may include, for example, on an endoscopic display or a separate monitor. For example, the endoscopic display or the separate monitor may be configured to emit a visual signal. The endoscopic display or the separate monitor may be in communication with the controller  48  that is configured to execute a stored program  50  to alter the visible signal based on the distance D 3  between the instrument sensor  28  and the fiducial sensor  10 . The instrument sensor  28  uses the signal generated by the fiducial sensor  10  to enable the controller  48  to execute the stored program  50  to calculate the distance D 3 , shown in  FIG. 6 , between the fiducial sensor  10  and the instrument sensor  28  (e.g., near the tip of the surgical device  26 ), and/or between the instrument sensor  28  (e.g., near the tip of the surgical device  26 ) and a vector normal to the hook structure  16 , such that when the surgical device  26  is below a threshold value of D 3 , the visual signal is generated. The visual signal may be, for example a solid or flashing light shown on the one or more displays  54 , such as the endoscopic display or the separate monitor. The visual signal may also increase in frequency or brightness, for example, as the distance D 3  decreases, such that as the surgical device  26  is navigated too close to the resection margin  24 , the visual signal&#39;s frequency and/or brightness increases. 
         [0057]    In one non-limiting example, the visual cue may be shown as a color changing sphere, for example, on one of the displays  54 . The color changing sphere may be representative of the tissue resection margin  24 , for example, such that the color changes based on the distance D 3  between the instrument sensor  28  and the fiducial sensor  10 . Thus, as the instrument sensor  28  approaches the fiducial sensor  10 , for example, the sphere may be shown in the display  54  in a first color. Likewise, as the instrument sensor  28  moves away from the fiducial sensor  10 , the sphere may be shown on the display  54  in a second color, for example, thereby allowing the surgeon to determine, visually, the distance D 3  between the instrument sensor  28  and the fiducial sensor  10 . 
         [0058]    Although quantitative, visual, and auditory cues may be provided to the clinician to identify the distance of the resection margin  24  from the surgical instrument  26 , the visual cue may further include a video overlay provided to the user on one or more of the displays  54  in communication with the controller  48 . For example, a video overlay may be implemented to fuse the laparoscopy images and virtual endoscopy images to confirm the position of the fiducial sensor  10  and the tissue mass  18 , as shown on the display  54  of  FIG. 7A . Based on the position of the laparoscope  56 , as shown on the display  54  of  FIG. 7B , the virtual endoscopy video of the three dimensional anatomy can be generated. The focal length and field of view may be input to control the virtual endoscopy view generated using a visualization toolkit camera, for example, of the three dimensional view. 
         [0059]    Haptic cues may also be provided to the user on the surgical device  26 . For example, a piezoelectric actuator  46  may be attached to the handle  30  of the surgical device  26  that is configured to emit a haptic signal. The piezoelectric actuator  46  may be in electrical communication with the controller that is configured to execute a stored program to alter the haptic signal based on the distance D 3  between the instrument sensor  28  and the fiducial sensor  10 . The instrument sensor  28  uses the signal generated by the fiducial sensor  10  to enable the controller to execute the stored program to calculate the distance D 3 , shown in  FIG. 6 , between the fiducial sensor  10  and the instrument sensor  28  such that when the surgical device  26  is below a threshold value of D 3 , the haptic signal is generated. The haptic signal may be, for example a vibration applied to the handle  30  of the surgical device  26 . The haptic signal may also increase in amplitude and/or frequency, for example, as the distance D 3  decreases, such that as the surgical device  26  is navigated too close to the resection margin  24 , the haptic signal&#39;s amplitude and/or frequency increases. 
         [0060]    Although the above described system and method for resecting a tissue mass was described for the surgery involving the lung, it is also applicable to resection of tumor or other non-tumor lesions in any other organ or structure of the body, for example resection for breast conserving surgery, sarcoma resection, partial nephrectomy or lung wedge resection surgery. In addition, the above described system and method for resecting a tissue mass is not limited to VATS or minimally invasive surgery.