Patent Description:
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.

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.

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.

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.

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.

<CIT> proposes a system for displaying image guidance data based on first image data related to an anatomical site, information on at least one tracking unit at the anatomical site, and second image data related to the anatomical site. Based thereon, desired emplacement information for an image of the first set of image data and a deformed version of the first set of image data are determined and finally used to determine the image guidance data.

Therefore, a tissue resection margin measuring device is needed that overcomes the above limitations.

The present invention relates to a system 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 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.

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 (e.g., in close proximity 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. The first signal indicates a position and an orientation of the tissue mass relative to the surgical instrument in real time and the second signal indicates a position and an orientation of the surgical instrument relative to the tissue mass. Further, the controller is configured to measure patient specific properties of the tissue mass and the surrounding tissue using a medical image acquired from one of a computed tomography (CT), magnetic resonance imaging (MRI), or fluoroscopic imaging system for use with a deformation algorithm to predict deformations to the tissue mass that occur during an operation for a patient. In addition, the controller calculates a distance between the first sensor and the second sensor based on the first signal and the second signal and implements the deformation algorithm that estimates or models changes occurring to a resection margin during operation of the surgical instrument as a result of the deformations of the tissue mass, the resection margin having a predetermined distance surrounding the tissue mass and being determined by creating a three dimensional envelope around the tissue mass. The predetermined distance is used to define a threshold value. When the surgical instrument is in a position less than the threshold value auditory, visual and/or haptic feedback is produced by the controller to be provided to a surgeon or the surgical instrument.

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.

In other embodiments, 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.

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 sensor indicates a position and an orientation of the tissue mass relative to the first sensor.

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 or J-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.

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.

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.

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.

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.

In another embodiment, the disclosure provides a method not forming part of the invention for resection of a tissue mass inside a patient. The method includes inserting a first sensor inside or next to the tissue mass (e.g., in close proximity) and capturing at least one image of the first sensor embedded within or next to (e.g., in close proximity 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.

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.

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.

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.

In other embodiments, the first sensor may embedded within a hook structure. The hook structure may be in the form of a T-bar or J-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.

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.

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.

In some embodiments, the method may further include emitting a visual signal on a monitor. The monitor may be in communication with the controller, 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.

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.

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.

<FIG> illustrate an example fiducial sensor <NUM> being inserted through a delivery needle <NUM>. The fiducial sensor <NUM> may be, for example a marker that includes a transmitter that measures position and orientation of a tissue mass <NUM> in real-time. The fiducial sensor <NUM> may be attached to a cable <NUM>, as shown in <FIG>, or the fiducial sensor <NUM> may be wireless. The fiducial sensor <NUM> may be embedded within a hook structure <NUM>, as shown in <FIG>. The hook structure <NUM> of the fiducial sensor <NUM> 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 <NUM> to be inserted through the delivery needle <NUM> and deployed through an opening <NUM> (i.e., the lumen) of the delivery needle <NUM> into the center or the periphery of the tissue mass <NUM>. The tissue mass <NUM> may be, for example, a tumor, nodule or lesion.

As shown in <FIG>, a more detailed view of the fiducial sensor <NUM> and hook structure <NUM> is shown. The hook structure <NUM> may include a tube portion <NUM> having a plurality of extensions <NUM> extending from one end of the tube portion <NUM> and a plurality of prongs <NUM> extending from an opposing end of the tube portion <NUM>. The tube portion <NUM> may be, for example, a nitinol tube having an outer diameter D<NUM> between about <NUM> millimeters and about <NUM> millimeters, and the hook structure <NUM> may have an overall length L between about <NUM> millimeters and about <NUM> millimeters. The tube portion <NUM> may be laser micro-machined into a cylindrical shape having the plurality of extensions <NUM> extending therefrom to secure the fiducial sensor <NUM> in place. In some embodiments, the fiducial sensor <NUM> may be an electromagnetic sensor that is attached to the proximal end of the hook structure <NUM> using a medical grade epoxy adhesive, such as AA-Bond FDA22.

The plurality of prongs <NUM>, as shown in <FIG>, may be configured to anchor the hook structure <NUM>, including the fiducial sensor <NUM>, into a tissue mass, such as the tissue mass <NUM> of <FIG>. The plurality of prongs <NUM> may be constructed from a superelastic shape memory alloy, such as nitinol. The plurality of prongs <NUM> may be bent, for example, and extend outwardly from a central axis Y of the hook structure <NUM>. The plurality of prongs <NUM> may also be heat-treated to ensure that the prongs <NUM> retain the curved shape and the phase structure of the nitinol is in the Martensite phase, for example. In the embodiment shown in <FIG>, the hook structure <NUM> includes three prongs <NUM>, however any suitable number of prongs may be provided in order to anchor the hook structure <NUM> to the tissue mass.

The fiducial sensor <NUM> along with the hook structure <NUM> may be inserted through a distal end of the delivery needle <NUM>, which may be an <NUM>-gauge needle, for example. The plurality of prongs <NUM> of the hook structure <NUM> may be inserted into the lumen <NUM> of the delivery needle <NUM> first. Advantageously, due to the superelastic nature of nitinol, the hook structure <NUM> can be easily inserted into the lumen <NUM> of the delivery needle <NUM>. The hook structure <NUM> may be deployed using a metal stylet (not shown) that is inserted through the lumen <NUM> of the delivery needle <NUM>. Upon being completely deployed, the plurality of prongs <NUM> will regain their original curved shape and open up to firmly anchor the hook structure <NUM> into the tissue mass <NUM>. The delivery needle <NUM> may then be removed after deployment of the hook structure <NUM>.

In some embodiments, the fiducial sensor <NUM> along with the hook structure <NUM> ,ay be inserted through the delivery needle <NUM> under real-time image guidance (i.e., CT, DynaCT, MRI, Ultrasound, etc.) and embedded within the tissue mass <NUM>, as shown in <FIG>, or next to the tissue mass <NUM> (e.g., in close proximity to), as shown in <FIG>. The fiducial sensor <NUM> may be embedded within or next to the tissue mass <NUM> before or during a surgical procedure. By using real-time image guidance, the spatial relationship (i.e., position and orientation) of the fiducial sensor <NUM> to the tissue mass <NUM> in three dimensions is known at all times. The hook structure <NUM> may be in the form of a T-bar or J-bar, for example, to anchor the fiducial sensor <NUM> within or next to the tissue mass <NUM> to inhibit migration. Advantageously, the force is at the center of the T-bar <NUM> due to the wire <NUM>, thereby facilitating anchoring the fiducial sensor <NUM> next to the tissue mass <NUM>. The fiducial sensor <NUM> embedded within or next to the tissue mass <NUM> will measure the position and orientation of the tissue mass <NUM> 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 <NUM> that is often difficult to determine.

In an alternative embodiment, shown in <FIG>, a second fiducial sensor <NUM> in the form of a T-bar, for example, may be put in a different location near the tissue mass <NUM>. The second fiducial sensor <NUM> may have a separate cable <NUM> from the first fiducial sensor <NUM>, as shown in <FIG>, or the first fiducial sensor <NUM> and the second fiducial sensor <NUM> may share the same cable <NUM>. The second fiducial sensor <NUM>, or any other such device, can be used to improve the localization of the tissue mass <NUM>, even when there may be deformation. For example, the second fiducial sensor <NUM> can be placed on the opposite side of the tissue mass <NUM> from the first fiducial sensor <NUM> and be recognized by the first fiducial sensor <NUM> through distortions in the Electromagnetic field. Therefore, by knowing that the tissue mass <NUM> is between these two sensors, the tissue mass <NUM> can be localized despite changes in the soft tissue.

Referring now to <FIG>, once the position and orientation of the tissue mass <NUM> is known, a resection margin <NUM> having a predetermined distance D<NUM> surrounding the tissue mass <NUM> is determined by creating a three dimensional envelope around the tissue mass <NUM>. The resection margin <NUM> may be manually set to the desired predetermined distance D<NUM>, for example two centimeters. The predetermined distance D<NUM> defines a threshold value so when a surgical device <NUM>, 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 <NUM> to ensure precise and complete resection of the tissue mass <NUM>.

Referring now to <FIG>, a conventional surgical device <NUM>, such as a surgical stapler, Bovi pencil, kitner laparoscope and/or any suitable cutting, resecting or ablating device, is shown. The surgical device <NUM> may include a handle <NUM> coupled to a fastening assembly <NUM> at an opposite end of the surgical device <NUM>. The fastening assembly <NUM> may be a single-use component that is removably connected to the handle <NUM>. That is, the fastening assembly <NUM> may be a cartridge that connects to the handle <NUM> and is removed after use. The fastening assembly <NUM> includes a housing <NUM> that contains a plurality of fasteners <NUM> that are secured to the tissue during resection of the tissue mass <NUM>. The fastening assembly <NUM> may also include a blade slot <NUM> that accommodates a blade (not shown) for cutting along the resection margin <NUM> of the tissue mass <NUM>.

In a preferred embodiment, the surgical device <NUM> includes a sleeve <NUM> that is dimensioned to slide over the housing <NUM>, for example, as shown in <FIG>. The sleeve <NUM> may be any commercially available sleeve, for example, that is configured to go over the housing <NUM> of the surgical device <NUM>. An instrument sensor <NUM> may be attached, by stitching for example, to the sleeve <NUM>. Alternatively, the instrument sensor <NUM> may be attached directly to the housing <NUM> of the surgical device <NUM> via any suitable adhesive or integrated within the housing <NUM> itself. Regardless of where the instrument sensor <NUM> is attached, either the sleeve <NUM> or the housing <NUM>, the instrument sensor <NUM> can measure the position and orientation of the surgical device <NUM> in the same imaging reference frame as the fiducial sensor <NUM> embedded within or next to the tissue mass <NUM>. In other words, the position of the surgical device <NUM> may be precisely measured with respect to the fiducial sensor <NUM> within or next to the tissue mass <NUM>, as will be described in further detail below. Since both the fiducial sensor <NUM> and the instrument sensor <NUM> 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.

The sleeve <NUM> may also include a display <NUM> that shows the user a distance D<NUM>, shown in <FIG>, of the surgical device <NUM> from the resection margin <NUM>, as will be described below. The display <NUM> may be attached to the handle <NUM> of the surgical device <NUM> 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 <NUM> located at the tip of the surgical device <NUM>, for example, may be displayed to the user.

Referring now to <FIG>, during operation, the fiducial sensor <NUM> is positioned next to or embedded within the tissue mass <NUM> using the plurality of prongs <NUM> of the hook structure <NUM>, as previously described. A CT/MRI/fluoroscopic examination, for example, is performed to acquire images of the fiducial sensor <NUM> embedded within the tissue mass <NUM>. The tissue mass <NUM> is then segmented from the preoperative diagnostic CT/MRI examination and a three dimensional model (not shown) of the tissue mass <NUM> is generated. The intra-operative images obtained during placement of the fiducial sensor <NUM> may be registered to the patient's diagnostic exam, and the location of the fiducial sensor <NUM> may be estimated. As previously discussed, the resection margin <NUM> having the predetermined distance D<NUM> surrounding the tissue mass <NUM> is displayed to the user on a monitor (not shown) as a three dimensional envelope or proximity sphere around the tissue mass <NUM>. The predetermined distance D<NUM> of the resection margin <NUM> may be determined based on the surgeon's preferences and the type of tissue mass <NUM>.

The surgical device <NUM> is then inserted into a body <NUM> (i.e., the patient), as shown in <FIG>, to cut the tissue mass <NUM> along the resection margin <NUM>. The fiducial sensor <NUM> embedded within or close to the tissue mass <NUM> is in electrical or wireless communication with a controller <NUM>. The controller <NUM> may be a programmable logic controller (PLC) and is configured to interpret a signal generated by the fiducial sensor <NUM>. The fiducial sensor <NUM> 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 <NUM>. The signal generated by the fiducial sensor <NUM> may be for example an electrical signal and the controller <NUM> may interpret this signal via a stored program <NUM>. The stored program <NUM> may include, for example a navigation system that is in communication with the fiducial sensor <NUM> and the instrument sensor <NUM>.

Similarly, the instrument sensor <NUM> 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 <NUM>. The signal generated by the instrument sensor <NUM> may be, for example, an electrical signal and the controller <NUM> may interpret this signal via a stored program <NUM>. The fiducial sensor <NUM> and the instrument sensor <NUM> communicate with the controller <NUM> and relay the position and orientation of the tissue mass <NUM> and the surgical device <NUM> using the navigation system. In some embodiments, the stored program <NUM> may be configured to run calibration and/or registration algorithms to track the distal tip of the surgical device <NUM> and the normal vector to the surgical device <NUM>. Thereafter, the stored program <NUM> of the controller <NUM> calculates the distance D<NUM>, shown in <FIG>, between the fiducial sensor <NUM> and the instrument sensor <NUM> such that when the surgical device <NUM> is below a threshold value of D<NUM>, an auditory, visual or haptic cue is generated for the user.

As the surgical device <NUM> is navigated towards the resection margin <NUM> of the tissue mass <NUM>, the surgical device <NUM> may excise the tissue mass <NUM> while minimizing damage to surrounding tissue due to both the fiducial sensor <NUM> and instrument sensor <NUM> 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 <NUM> and the instrument sensor <NUM> on the surgical device <NUM>, the distance D<NUM> from the tissue mass <NUM> and the surgical device <NUM> may be known to the user and visible on the display <NUM> at all times. As a result, the desired resection margin <NUM> may be maintained at all times, thereby ensuring complete resection of the tissue mass <NUM>. In an alternative embodiment, the position and orientation data of the tissue mass <NUM> and the surgical device <NUM> may lock or unlock the surgical device <NUM> to inhibit erroneous resection of the tissue mass <NUM>.

In some embodiments, the stored program <NUM> of the controller <NUM> may be configured to include one or more deformation algorithm that estimates or models changes that can occur to the resection margin <NUM> during operation, as a result of deformations of the tissue mass <NUM> and/or the surrounding tissue. The deformation algorithms attempt to account for any such changes to the resection margin <NUM> to provide more accurate resection margins to a user during operation, which aids in complete resection of the tissue mass <NUM> while limiting damage to, or removal of, healthy, surrounding tissue.

In one non-limiting example, the stored program <NUM> includes a deformation algorithm that assumes that the tissue mass <NUM> (e.g., a breast tumor) is rigid and that the surrounding tissue (e.g., the parenchyma) deforms. The algorithm assumes every point on the tissue mass <NUM> moves along with the fiducial sensor <NUM>, which is anchored to the tissue mass <NUM> as described above. In another non-limiting example, the stored program <NUM> includes a deformation algorithm that assumes the tissue mass <NUM> is a rigid object moving through a viscoelastic or fluid medium. In yet another non-limiting example, patient specific properties of the tissue mass <NUM> and the surrounding tissue can be measured, for example, via a CT/MRI/fluoroscopic examination, to predict deformations to tissue mass <NUM> that occur during an operation for that specific patient. It should be appreciated that the deformation algorithms of the stored program <NUM> may operate on a real-time basis with the navigation system of the stored program <NUM>.

More specifically, a tissue mass <NUM> (e.g., a tumor) can be segmented from volumetric images obtained, for example, from the CT/MRI/fluoroscopic examination, to create a surface model. Based upon a default resection margin inputted into the navigation system by a user, a segmented tumor label map can be dilated to the desired resection margin to create a surface model corresponding to the resection margin. Due to deformation of the tumor and the surrounding tissue, the resection margin can change, for example, due to movement of the patient. A linear elastic volumetric finite element model ("FEM") mesh can therefore be created from the surface model of the tumor and the resection margin. Using the FEM model, an estimate of the displacement of the other nodes of tissue mass <NUM> can be made, given the real-time position measurement of the fiducial sensor <NUM>. Stiffness values may not be entirely accurate for the FEM model, and the FEM model may be constrained in one example to the tissue mass <NUM> and the surrounding tissue. Uncertainty measurements of the tissue mass <NUM> and the surrounding tissue deformation can therefore be provided to a user in real-time based upon the uncertainty in the estimated stiffness values of the FEM mesh.

As described above, auditory, visual and haptic cues may be provided to the surgeon and/or the surgical device <NUM> to identify the resection margin <NUM> to ensure precise and complete resection of the tissue mass <NUM>. For example, an audible source <NUM> may be configured to emit an audible signal. The audible source <NUM> may be in communication with the controller48 that is configured to execute the stored program <NUM> to alter the audible signal based on the distance D<NUM> between the instrument sensor <NUM> and the fiducial sensor <NUM>. The instrument sensor <NUM> uses the signal generated by the fiducial sensor <NUM> to enable the controller <NUM> to execute the stored program <NUM> to calculate the distance D<NUM>, shown in <FIG>, between the fiducial sensor <NUM> and the instrument sensor <NUM> such that when the surgical device <NUM> is below a threshold value of D<NUM>, 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<NUM> decreases, such that as the surgical device <NUM> is navigated too close to the resection margin <NUM>, the audible signal's frequency or duty cycle increases.

In addition to the auditory cues, visual cues may also be provided to the user on one or more displays <NUM> in communication with the controller <NUM>. The one or more displays <NUM> 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 <NUM> that is configured to execute a stored program <NUM> to alter the visible signal based on the distance D<NUM> between the instrument sensor <NUM> and the fiducial sensor <NUM>. The instrument sensor <NUM> uses the signal generated by the fiducial sensor <NUM> to enable the controller <NUM> to execute the stored program <NUM> to calculate the distance D<NUM>, shown in <FIG>, between the fiducial sensor <NUM> and the instrument sensor <NUM> (e.g., near the tip of the surgical device <NUM>), and/or between the instrument sensor <NUM> (e.g., near the tip of the surgical device <NUM>) and a vector normal to the hook structure <NUM>, such that when the surgical device <NUM> is below a threshold value of D<NUM>, the visual signal is generated. The visual signal may be, for example a solid or flashing light shown on the one or more displays <NUM>, 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<NUM> decreases, such that as the surgical device <NUM> is navigated too close to the resection margin <NUM>, the visual signal's frequency and/or brightness increases.

In one non-limiting example, the visual cue may be shown as a color changing sphere, for example, on one of the displays <NUM>. The color changing sphere may be representative of the tissue resection margin <NUM>, for example, such that the color changes based on the distance D<NUM> between the instrument sensor <NUM> and the fiducial sensor <NUM>. Thus, as the instrument sensor <NUM> approaches the fiducial sensor <NUM>, for example, the sphere may be shown in the display <NUM> in a first color. Likewise, as the instrument sensor <NUM> moves away from the fiducial sensor <NUM>, the sphere may be shown on the display <NUM> in a second color, for example, thereby allowing the surgeon to determine, visually, the distance D<NUM> between the instrument sensor <NUM> and the fiducial sensor <NUM>.

Although quantitative, visual, and auditory cues may be provided to the clinician to identify the distance of the resection margin <NUM> from the surgical instrument <NUM>, the visual cue may further include a video overlay provided to the user on one or more of the displays <NUM> in communication with the controller <NUM>. 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 <NUM> and the tissue mass <NUM>, as shown on the display <NUM> of <FIG>. Based on the position of the laparoscope <NUM>, as shown on the display <NUM> of <FIG>, 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.

Haptic cues may also be provided to the user on the surgical device <NUM>. For example, a piezoelectric actuator <NUM> may be attached to the handle <NUM> of the surgical device <NUM> that is configured to emit a haptic signal. The piezoelectric actuator <NUM> 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<NUM> between the instrument sensor <NUM> and the fiducial sensor <NUM>. The instrument sensor <NUM> uses the signal generated by the fiducial sensor <NUM> to enable the controller to execute the stored program to calculate the distance D<NUM> , shown in <FIG>, between the fiducial sensor <NUM> and the instrument sensor <NUM> such that when the surgical device <NUM> is below a threshold value of D<NUM>, the haptic signal is generated. The haptic signal may be, for example a vibration applied to the handle <NUM> of the surgical device <NUM>. The haptic signal may also increase in amplitude and/or frequency, for example, as the distance D<NUM> decreases, such that as the surgical device <NUM> is navigated too close to the resection margin <NUM>, the haptic signal's amplitude and/or frequency increases.

Claim 1:
A system for resecting a tissue mass (<NUM>), the system comprising:
a surgical instrument (<NUM>);
a first sensor (<NUM>) for measuring a first signal, the first sensor (<NUM>) dimensioned to fit at least one of inside and next to the tissue mass (<NUM>), wherein the first signal indicates a position and an orientation of the tissue mass (<NUM>) relative to the surgical instrument (<NUM>) in real time;
a second sensor (<NUM>) for measuring a second signal, the second sensor (<NUM>) coupled to the surgical instrument (<NUM>), wherein the second signal indicates a position and an orientation of the surgical instrument (<NUM>) relative to the tissue mass (<NUM>);
a controller (<NUM>) in communication with the first sensor (<NUM>) and the second sensor (<NUM>); and
wherein the controller (<NUM>) is further configured to measure patient specific properties of the tissue mass (<NUM>) and the surrounding tissue using a medical image acquired from one of a computed tomography (CT), magnetic resonance imaging (MRI), or fluoroscopic imaging system for use with a deformation algorithm to predict deformations to the tissue mass (<NUM>) that occur during an operation for a patient, and
wherein the controller (<NUM>) calculates a distance between the first sensor (<NUM>) and the second sensor (<NUM>) based on the first signal and the second signal and implements the deformation algorithm that estimates or models changes occurring to a resection margin (<NUM>) during operation of the surgical instrument (<NUM>) as a result of the deformations of the tissue mass (<NUM>), the resection margin (<NUM>) having a predetermined distance (D<NUM>) surrounding the tissue mass (<NUM>) and being determined by creating a three dimensional envelope around the tissue mass (<NUM>), wherein the predetermined distance (D<NUM>) is used to define a threshold value such that when the surgical instrument (<NUM>) is in a position less than the threshold value auditory, visual and/or haptic feedback is produced by the controller to be provided to a surgeon.