Abstract:
A system and method for a procedure that can be performed on any appropriate subject. Procedures can include assembling any appropriate work piece or installing members into a work piece, such as an airframe, autoframe, etc. Regardless of the subject, generally the procedure can have a selected result that is efficacious. The efficacious result may be the desired or best result for the procedure. The system and method can be used in confirming a selected result that can be efficacious.

Description:
FIELD 
     The present disclosure is directed to planning and confirming a procedure performed on a subject, and particularly to a method and system to assist in achieving a selected procedure and confirming the procedure. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     A procedure can be performed on any appropriate subject. For example, a procedure can be performed on a patient to position an implant in the patient. Though procedures can also include assembling any appropriate work piece or installing members into a work piece, such as an airframe, autoframe, etc. Regardless of the subject, generally the procedure can have a selected result that is efficacious. The efficacious result may be the desired or best result for the procedure. 
     A procedure on a human patient can be a surgical procedure performed to insert an implant, such as a pedicle screw. The pedicle screw can be placed in the patient according to appropriate techniques, such as an open procedure where a surgeon can view the procedure. The surgeon can then view images of the implanted screw in the patient to analyze placement of the screw. The images acquired of the patient and the screw, however, may include artifacts due to the imaging technique and the material of the implant. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     A system is provided that can be used to confirm or determine a position of an implant. During a procedure, such as a surgical procedure, an implant or member can be placed in a subject. After the procedure is complete, an image can be acquired of the subject. A pre-formed model (such as a computer aided or assisted design (CAD) model) can be overlayed or superimposed on the acquired image data at the determined location of the implanted member to confirm placement of the implant. The overlayed image can be used to confirm completion of a planned procedure as well. 
     According to various embodiments, a surgical procedure can be performed with a navigation system. During a navigated procedure an instrument, such as a surgical instrument or implant, can be tracked relative to a patient. A planning procedure or system can also be provided and used that can illustrate and/or determine a procedure to be performed on a patient. In addition, a planning module can include a system that can execute instructions to illustrate and determine a procedure for achieving a result in a patient. A database storage system can be used to save and accumulate preferred portions of a procedure, such as entry points and trajectories. 
     In addition, image data can be acquired of the patient prior to implantation and subsequent to implantation, both of which can be either intra-, pre-, and post-operatively acquired, to assist in confirming placement of an implant. For example, as discussed further herein, pedicle screws can be placed in one or more vertebra of a patient. The placement of the pedicle screws can be confirmed or checked with the use of image data acquired of the patient. Further, computer aided or assisted design (CAD) models can be used to assist in viewing a placement of implants relative to the patient. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is an environmental view of an operating theatre including an optional imaging system and a navigation system; 
         FIG. 2  is a flow chart illustrating a procedure for performing and confirming placement of an implant in a patient; 
         FIGS. 3A-3C  illustrate image data of a spine of a patient from various perspectives; 
         FIG. 4  is an illustration of a detail of an instrument for inserting an implant into a patient; 
         FIG. 5  is a view of a display device showing image data of a patient and an icon of an implant relative to the image data; 
         FIG. 6  is a display illustrating image data of a portion of patient with an implant implanted; 
         FIG. 7  is a view of a display with an augmented image data with a model superimposed on implant image data; 
         FIG. 8  is a view of a display with image data and model of an implant superimposed on the image data; and 
         FIG. 9  is a view of a display showing a plan for a procedure. 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. 
       FIG. 1  is a diagram illustrating an overview of a navigation system  10  that can be used for various procedures. The navigation system  10  can be used to track the location of an item, such as an implant or an instrument (as discussed herein), relative to a subject, such as a patient  14 . It should further be noted that the navigation system  10  may be used to navigate any type of instrument, implant, or delivery system, including: guide wires, arthroscopic systems, orthopedic implants, spinal implants, deep brain stimulation (DBS) probes, etc. Moreover, the instruments may be used to navigate or map any region of the body. The navigation system  10  and the various tracked items may be used in any appropriate procedure, such as one that is generally minimally invasive or an open procedure. 
     The navigation system  10  can interface with an imaging system  12  that is used to acquire pre-operative, intra-operative, or post-operative, or real-time image data of the patient  14 . It will be understood, however, that any appropriate subject can be imaged and any appropriate procedure may be performed relative to the subject. In the example shown, the imaging system  12  comprises an O-arm® imaging device sold by Medtronic Navigation, Inc. having a place of business in Louisville, Colo., USA. The imaging device  12  may have a generally annular gantry housing  20  that encloses an image capturing portion  22 . The image capturing portion  22  may include an x-ray source or emission portion  26  and an x-ray receiving or image receiving portion  28  located generally or as practically possible 180 degrees from each other and mounted on a rotor (not illustrated) relative to a track of the image capturing portion  22 . The image capturing portion  22  can be operable to rotate 360 degrees during image acquisition. The image capturing portion  22  may rotate around a central point or axis, allowing image data of the patient  14  to be acquired from multiple directions or in multiple planes. The imaging system  12  can include those disclosed in U.S. Pat. Nos. 7,188,998; 7,108,421; 7,106,825; 7,001,045; and 6,940,941; all of which are incorporated herein by reference. Other possible imaging systems can include C-arm fluoroscopic imaging systems which can also generate three-dimensional views of the patient  14 . 
     The position of the image capturing portion  22  can be precisely known relative to any other portion of the imaging device  12 . In addition, as discussed herein, the precise knowledge of the position of the image capturing portion  22  can be used in conjunction with a tracking system  29  to determine the position of the image capturing portion  22  and the image data relative to the tracked subject, such as the patient  14 . 
     The tracking system  29  can include various portions that are associated or included with the navigation system  10 . The tracking system  29  can also include a plurality of types of tracking systems including an optical tracking system that includes an optical localizer  40  and/or an EM tracking system that can include an EM localizer  42 . Various tracking devices, including those discussed further herein, can be tracked with the tracking system  29  and the information can be used by the navigation system  10  to allow for a display of a position of an item. Briefly, tracking devices, such as a patient tracking device  48 , an imaging device tracking device  50 , and an instrument tracking device  52 , allow selected portions of the operating theater to be tracked relative to one another with the appropriate tracking system, including the optical localizer  40  and/or the EM localizer  42 . 
     It will be understood that any of the tracking devices  48 - 52  can be optical or EM tracking devices, or both, depending upon the tracking localizer used to track the respective tracking devices. It will be further understood that any appropriate tracking system can be used with the navigation system  10 . Alternative tracking systems can include radar tracking systems, acoustic tracking systems, ultrasound tracking systems, and the like. 
     An exemplarily EM tracking system can include the STEALTHSTATION® AXIEM™ Navigation System, sold by Medtronic Navigation, Inc. having a place of business in Louisville, Colo. Exemplary tracking systems are also disclosed in U.S. patent application Ser. No. 10/941,782, filed Sep. 15, 2004, and entitled “METHOD AND APPARATUS FOR SURGICAL NAVIGATION”; U.S. Pat. No. 5,913,820, titled “Position Location System,” issued Jun. 22, 1999 and U.S. Pat. No. 5,592,939, titled “Method and System for Navigating a Catheter Probe,” issued Jan. 14, 1997, all herein incorporated by reference. 
     Further, for EM tracking systems it may be necessary to provide shielding or distortion compensation systems to shield or compensate for distortions in the EM field generated by the EM localizer  42 . Exemplary shielding systems include those in U.S. patent application Ser. No. 10/252,258, filed on Sep. 23, 2002, published as U.S. Pat. App. Pub. No. 2003/0117135 and U.S. Pat. No. 6,747,539, issued on Jun. 8, 2004; distortion compensation systems can include those disclosed in U.S. patent application Ser. No. 10/649,214, filed on Jan. 9, 2004, published as U.S. Pat. App. Pub. No. 2004/0116803, all of which are incorporated herein by reference. 
     With an EM tracking system, the localizer  42  and the various tracking devices can communicate through an EM controller  44 . The EM controller can include various amplifiers, filters, electrical isolation, and other systems. The EM controller  44  can also control the coils of the localizer  42  to either emit or receive an EM field for tracking. A wireless communications channel, however, such as that disclosed in U.S. Pat. No. 6,474,341, entitled “Surgical Communication Power System,” issued Nov. 5, 2002, herein incorporated by reference, can be used as opposed to being coupled directly to the EM controller  44 . 
     It will be understood that the tracking system may also be or include any appropriate tracking system, including a STEALTHSTATION® TRIA®, TREON®, and/or S7™ Navigation System having an optical localizer, similar to the optical localizer  94 , sold by Medtronic Navigation, Inc. having a place of business in Louisville, Colo. Further alternative tracking systems are disclosed in U.S. Pat. No. 5,983,126, to Wittkampf et al. titled “Catheter Location System and Method,” issued Nov. 9, 1999, which is hereby incorporated by reference. Other tracking systems include an acoustic, radiation, radar, etc. tracking or navigation systems. 
     The imaging system  12  can include a support housing or cart  56 . The imaging system  12  can further include a separate image processing unit  58  that can be housed in the cart  56 . The navigation system  10  can include the navigation processing unit  60  that can communicate or include a navigation memory  62 . The navigation processing unit  60  can receive information, including image data, from the imaging system  12  and tracking information from the tracking systems  29 , including the respective tracking devices  48 - 52  and the localizers  40 - 42 . Image data can be displayed as an image  64  on a display device  66  of a workstation or other computer system  68 . The workstation  68  can include appropriate input devices, such as a keyboard  70 . It will be understood that other appropriate input devices can be included, such as a mouse, a foot pedal or the like. 
     The image processing unit  58  processes image data from the imaging system  12  and transmits it to the navigation processor  60 . It will be further understood, however, that the imaging system  12  need not perform any image processing and it can transmit the image data directly to the navigation processing unit  60 . Accordingly, the navigation system  10  may include or operate with a single or multiple processing centers or units that can access single or multiple memory systems based upon system design. The patient  14  can be fixed onto an operating table  72 , but is not required to be fixed to the table  72 . The table  72  can include a plurality of straps  74 . The straps  74  can be secured around the patient  14  to fix the patient  14  relative to the table  72 . Various apparatuses may be used to position the patient  14  in a static position on the operating table  72 . Examples of such patient positioning devices are set forth in commonly assigned U.S. patent application Ser. No. 10/405,068 entitled “An Integrated Electromagnetic Navigation And Patient Positioning Device”, filed Apr. 1, 2003 which is hereby incorporated by reference. Other known apparatuses may include a Mayfield® clamp. 
     Also, the position of the patient  14  relative to the imaging system  12  can be determined by the navigation system  10  with the patient tracking device  48  and the imaging system tracking device  50 . Accordingly, the position of the patient  14  relative to the imaging system  12  can be determined. An exemplary imaging system, such as the O-arm® can know its position and be repositioned to the same position within about 10 microns. This allows for a substantially precise placement of the imaging system  12  and precise determination of the position of the imaging device  12 . Precise positioning of the imaging portion  22  is further described in U.S. Pat. Nos. 7,188,998; 7,108,421; 7,106,825; 7,001,045; and 6,940,941; all of which are incorporated herein by reference. Subject or patient space and image space can be registered by identifying matching points or fiducial points in the patient space and related or identical points in the image space. The imaging device  12 , such as the O-arm® imaging device sold by Medtronic, Inc., can be used to generate image data at a precise and known position. This can allow image data that is automatically or “inherently registered” to the patient  14  upon acquisition of the image data. Essentially, the position of the patient  14  is known precisely relative to the imaging system  12  due to the accurate positioning of the imaging system  12 . This allows points in the image data to be known relative to points of the patient  14  because of the known precise location of the imaging system  12 . 
     Alternatively, manual or automatic registration can occur by matching fiducial points in image data with fiducial points on the patient  14 . Registration of image space to patient space allows for the generation of a translation map between the patient space and the image space. According to various embodiments, registration can occur by determining points that are substantially identical in the image space and the patient space. The identical points can include anatomical fiducial points or implanted fiducial points. Exemplary registration techniques are disclosed in Ser. No. 12/400,273, filed on Mar. 9, 2009, incorporated herein by reference. 
     Once registered, the navigation system  10  with or including the imaging system  12 , can be used to perform selected procedures. Selected procedures can use the image data generated or acquired with the imaging system  12 . Further, the imaging system  12  can be used to acquire image data at different times relative to a procedure. As discussed herein, image data can be acquired of the patient  14  subsequent to a selected portion of a procedure for various purposes, including confirmation of the portion of the procedure. 
     With continuing reference to  FIG. 1 , the imaging system  12  can generate actual or virtual three dimensional images of the patient  14 . The patient  14  can be placed relative to the imaging system  12  to allow the imaging system  12  to obtain image data of the patient  14 . To generate 3D image data, the image data can be acquired from a plurality of views or positions relative to the patient  14 . The 3D image data of the patient  14  can be used alone or with other information to assist in performing a procedure on the patient  14  or an appropriate subject. It will be understood, however, that any appropriate imaging system can be used, including magnetic resonance imaging, computed tomography, fluoroscopy, etc. 
     With reference to  FIG. 2 , and  FIGS. 3A-8 , a flow chart  100  illustrates a method for confirming placement of an implant after an implantation procedure as illustrated in  FIGS. 3A-8 . It will be understood that although the flowchart  100  describes and is directed to a method of placing pedicle screws  120  ( FIG. 3 ) in a vertebra  124  ( FIG. 4 ), the procedure can be used to confirm placement of any appropriate implant in any appropriate portion of the anatomy, such as an intramedullary (IM) rod in a long bone (e.g. a femur), a knee or hip replacement prosthesis, or any other appropriate procedure. Accordingly, the method in flowchart  100  will be understood to encompass selected procedures beyond pedicle screw placement. In addition, it will be understood that the method of the flowchart  100  can be used to confirm placement of any appropriate member in any appropriate structure. For example, placement of a member, including a spike, into a radio lucent work piece, such as a wood board, can also be confirmed with the procedure in the flowchart  100 . 
     The method in the flowchart  100  can begin at start block  102 . A procedure can then be selected in block  104 . The procedure can be any appropriate procedure, such as the placement of the pedicle screw within the vertebra  124  of a patient  14 . It will be understood that the placement of the pedicle screw  120  in the vertebra  124  of the patient  14  can be performed for any appropriate procedure, such as spinal fusion or vertebral rigidity. Regardless of the procedure selected in block  104 , first image data of a subject can be acquired in block  106 . 
     The image data  64  can be any appropriate image data, such as x-ray image data of a single vertebra, illustrated in  FIG. 3A . The image data  64  can be displayed on the display  66  or can be acquired and saved in the memory or storage system  62  of the navigation system  10 , can be used for later confirmation of a procedure, or can be used for both. Briefly, a first image data of the subject can be image data acquired of the subject or the patient  14  prior to any portion of a surgical intervention being performed. For example, the patient  14  can be imaged with the imaging system  12  substantially immediately after entering an operating theatre and prior to performing any surgical procedures, such as forming an incision. It will be further understood that the first image data of the subject acquired in block  106  can be acquired prior to the patient  14  entering the surgical theatre. Regardless of the timing of acquiring the first image data, the first image data is image data of the patient or subject  14  having been unaltered by a surgical procedure. As discussed further herein, in relation to the method in the flowchart  100 , this image data can be used along with later or second acquired image data and a model (e.g. a CAD model) of an implant for confirmation of placement of an implant in the patient  14 . The first acquired image data can be subtracted from the second acquired image data to substantially define only the anatomy of the patient  14  that has not been affected by a surgical procedure or artifacts that may be induced by an implant member in the image data. 
     After the first image data is acquired in block  106 , the first image data can be optionally transferred to a data processor in block  112 . The image data transferred to the data processor in block  112  can be all first image data acquired of the patient  14  in the first image data from block  106 . As illustrated in  FIGS. 3A-3C , image data can be acquired of the patient  14  from a plurality of perspectives or viewpoints. 
     The first image data acquired in block  106  can be saved or transferred to any appropriate processing core or system, or can simply be directly transferred or maintained to be accessed by a single processing unit. As discussed above, the imaging processing unit  58  can be incorporated in the imaging system  12  and the navigation processor  60  can be included with the navigation workstation  68 . Accordingly, the two processing units can communicate and image data can be transferred between. Alternatively, the image data can be simply acquired and transferred to the navigation processor  60 . Regardless, it will be understood that the navigation system  10  can process the image data with a single or multiple processing unit or cores as understood by one skilled in the art. 
     Once the first image data is acquired in block  106  and optionally transferred to a processor in block  112 , the selected procedure can be performed in block  114 . As illustrated in  FIG. 4 , the procedure can include placement of a pedicle screw  120  into the patient  14 . As is generally understood, the anatomy of the patient  14  can include a vertebra  124  into which the pedicle screw  120  can be positioned or implanted. The pedicle screw  120  can be implanted with an appropriate surgical instrument, such as a screw gun  126  or can be implanted with an appropriate manual driver (not illustrated) such as the CD Horizon® Legacy™ System manual driver, sold by Medtronic Spine and Biologics having a place of business in Minneapolis, Minn. Regardless of the instrument used to implant the pedicle screw  120 , the instruments or the pedicle screw can include a tracking device  52 . The tracking device  52  can be tracked by within the navigation system  10 , such as with either or both of the tracking systems including the optical localizer  40  or the EM localizer  42  during the surgical procedure. 
     The tracking device  52  allows the navigation system  10  to determine and illustrate a position of the pedicle screw  120 , the implantation instrument  126 , or combinations thereof relative to image data acquired of the patient  14 . For example, as illustrated in  FIG. 5 , an icon  120   i  can be superimposed on the first acquired image data  64   a  of the patient  14  as the pedicle screw  120  is moved towards the vertebra  124  of the patient  14 . As illustrated in  FIG. 5 , as the pedicle screw  120  moves towards the vertebra  124 , an icon  120   i  can be illustrated to move towards and into the vertebra image data  64   a . The icon  120   i  can be a preformed CAD model of the screw including a priori precise dimension information. The preformed model can be stored in the navigation memory device  62  can be accessed by an appropriate processor, such as the navigation processor  60 . It will also be understood that the image data  64   a  of the vertebra can include other information such as a centerline icon  140  that can be automatically or manually determined relative to the image data  64   a.    
     The navigation system  10 , by tracking the pedicle screw  120  either directly or through a navigated instrument, can be used to illustrate or determine a position of the pedicle screw  120  relative to the vertebra  124 . By illustrating an icon  120   i  superimposed on the image data  64   a  of the patient  14 , the user  54  can guide or be given feedback regarding the position of the pedicle screw  120  relative to the patient  14  and the vertebra  124 . Accordingly, at a selected time, the user can select to stop driving the pedicle screw  120  into the patient&#39;s  14  vertebra  124  based upon the position of the icon  120   i  or other appropriate information. 
     Once the user  54  determines to stop driving the pedicle screw  120  into the vertebra  124 , second image data  154  of the subject can be acquired in block  150 . The second image data acquired of the patient  14  in block  150  can be image data that is acquired with the imaging system  12 , or any appropriate imaging system, of the patient  14  after the pedicle screw  120  is positioned within the vertebra  124 . As illustrated in  FIG. 6 , the second image data of the vertebra  124  can include image data of the vertebra  124 ′ and image data of one or more pedicle screws  120 ′. The image data of the pedicle screws  120 ′ can be or may be distorted or include artifacts due to the type of imaging modality used by the imaging system  12 . For example, the pedicle screw  120  can be formed of a metal which can generate artifacts in x-ray image data acquired of the patient  14 . The artifacts can generate a fuzzy or distorted image of the true dimensions of the pedicle screw  120  in the second acquired image data. 
     After the second image data has been acquired of the patient  14  in block  150 , the image data can be displayed as a second image  154  on the display  66 , as illustrated in  FIG. 6 , and/or transferred to in the appropriate processor (e.g. the imaging processor  58  or the navigation processor  60 ) block  156  of the flowchart  100 . It will be understood, as discussed above, that transferring the image data to a second image data processor is not required. Rather the second image data can also be processed in the processing unit  58  of the imaging system  12  or in the navigation processing unit  60 , or in any appropriate processing unit. As discussed above, the inclusion of multiple processors can be used to speed processing and specialization of processing tasks. It will be understood, however, that a single processor can execute various program modules to process image data, navigate, track instruments, and track devices and the like. Accordingly, including more than one processing unit is not a requirement. 
     The second image data, which can be referred to herein by the second image  154  formed by the second image data, can be compared or subtracted from the first image data, which can be referred to herein by the first image  64   a - c  formed by the image data. As illustrated in  FIG. 6 , the second image data  154  can include image data of both the vertebra  124 , such as an x-ray image  124 ′, and can also include image data of the pedicle screw  120 , as pedicle screw shadows  120 ′. It will be understood that more than one pedicle screw can be implanted into a single vertebra for a single procedure. According to various embodiments, the imaging device  12  can cause artifacts in the image data  154  after the implant  120  is positioned within the anatomy of the patient  14 . 
     As illustrated schematically in  FIG. 6 , the shadows of the pedicle screws  120 ′ are indistinct or lack sharp edges. The fuzziness can be caused due to artifacts in the imaging process of the implants  120 , via processing artifacts, or other imaging issues with imaging the implants  120 . Regardless, the second image data  154  that includes image data relating to the implants  120  that have an implant into the patient  14  while performing the selected procedure in block  114  can lead to an imprecise determination of position of the implants  120  in the patient  14  with the second image data  154 . 
     Subtraction of the first image data from the second image data in block  158  can be performed to identify or eliminate from the second image data  154  substantially all of the second image data  154  that is not related to the implants  120  in the vertebra  124 . Also, tracking information and a priori information regarding the dimensions of the implant or interaction of the implant can be used to determine more precisely the position of the screws  120 . A priori information can include precise screw or other implant dimensions, including width, length, etc. A priori information can include interactions such as dilation of the anatomy from the screw, etc. 
     The screws are tracked relative to the patient  14  that has been registered to the image data  64 ,  154 , as discussed above. Thus, a position of the screw  120  can be determined in the image data  154  based on the tracked position of the screw  120 . The dimensions of the screw  120 , based on the a priori information in the CAD model (or other model information) can be used with the determined location to assist in determining the position of the screw  120 ′ in the second image data  154 . This can also help with the subtraction, as discussed herein. 
     As illustrated in  FIG. 7 , subtraction of the anatomical image data included in the first image data  64  can be used to generate augmented second image data of the implanted member in block  160 . The generated augmented second image data of the implant, as illustrated in  FIG. 7 , can include image data which only occurs in the second image data  154  after the procedure is performed. Generally, the first image data  64  can be subtracted from the second image data  154  to generate the augmented image data  154 ′. In addition, the a priori information can be used to assist in the subtraction of the second image data that does not occur due to the implant image  120 ′. 
     The generated augmented second image of the implanted member in block  160  can generate augmented second image data  154 ′. The augmented second image data  154 ′ can include substantially only the image data as it relates to the placement or is caused by the implants  120  positioned in the patient  14 . In the augmented second image data  154 ′, the shadows of the implants  120 ′ can be illustrated on the display  66 , either alone or with other icons, as discussed further herein. 
     In addition, the generation of the augmented second image data of the implanted member in block  160  can also be generated using information relating to the navigation (including location and orientation, sometimes referred together as position) of the implants  120  into the vertebra  124 . As discussed above, the instrument  126  can be tracked as the procedure is performed. The position of the screws  120  can be illustrated relative to the first image data  64 , as illustrated in  FIG. 5  where the pedicle screw icon  120   i  is shown relative to the vertebra image  124 ′. The position of the pedicle screw  120  can therefore be determined, via tracking the screw  120  with the tracking device  52 , relative to the patient  14 . As discussed above, the patient  14  can be registered to the image data  64  and tracked with the patient tracking device  48 . In addition, various landmarks, such as the centerline  140 , can be determined relative to the tracked position of the pedicle screws. Accordingly, the position of the pedicle screw  120  that is tracked relative to the patient  14  can also be used in identifying and determining the portion of the second image data  154  that substantially defines the pedicle screw  120  alone. Moreover, the known or a priori structure of the pedicle screw  120  can be inputted into the system, such as the navigation system  10 , and further be used to identify the portion of the second image data  154  that is the pedicle screw  120 . For example, a pedicle screw can be known to have a selected length X maximum width Y and a thread width TW that can also be used to identify the portion of the second image data that relates to the pedicle screw  120 . The dimensions of the screw  120  can be part of a pre-formed model (e.g. a CAD model) including a priori dimension information of the screw  120 . 
     All of the information, including the tracking data, the dimensions of the pedicle screw  120 , and the subtraction of the first image data  64  can be used to generate the augmented second image data  154 ′. Once the augmented second image data  154 ′ has been generated in block  160 , the portion of the image data that is the pedicle screw  120 ′ can be overlaid or replaced with the pre-formed or CAD model of the implanted member in block  166 . The CAD model can include or be the icon  120   i  of the screw being implanted that is overlaid substantially on the augmented second image data  154 ′ that identifies the implanted positions of the screws  120 . The CAD model can include the precise dimensions of the implanted member  120  and can be overlaid on the augmented image data  154 ′ at the positions identified as the area relating to the implants  120 . It will be understood that the image data  64 , the second image data  154 , and the augmented image data  154 ′ can all be two dimensional and/or three dimensional data. Further, the icons  120   i  can also include three dimensional structures or information and can be overlaid in orientation and location relative to the acquired image data  154 ′ and landmarks therein, such as the centerline  140 . Therefore, the icons  124   i  can be overlaid at the determined position of the implanted members  120  in the image data. 
     After the CAD representation of the implants  120   i  has been overlaid or positioned at the identified position of the implants in block  166 , the augmented or generated second image data  154 ′ can be removed in block  170  leaving substantially only the icons  120   i  representing the CAD models. A determination of the position of the implanted member can be made in block  172  which can include the tracked information regarding the implanted implants  120 , the augmented image data  154 ′, and other information. The position of the implants can be used for confirmation, as discussed below. 
     Once the overlaid or determined position of the icons  120   i ′ is determined, they can be superimposed onto the second image data  154  and displayed on the display  66  in block  180 . The user  54  can then observe the second image data with the superimposed icons in block  182 . The second image data  154 , as discussed above, is acquired after the implantation of the implant  120  has occurred. Accordingly, the second image data  154  is a substantially concurrent or current image of the patient  14 . Therefore, having the icons  120   i  superimposed on the second image data  154  can provide a substantially clear indication to the user  54  of the precise location of the implanted members  120  in the vertebra  124 . Because the position of the implants  120  was determined substantially precisely via the image subtraction, the tracking information, and other information, the icons  120   i  are superimposed on the second image data  154  at substantially the precise location where they are implanted in the patient  14 . The icons  120   i , however, do not suffer from any artifacts or blurring due to imaging artifacts of the implants  120 . Accordingly, the icons  120   i  provide a substantially precise and clear image to the user  54  of the position of the implants  120  in the vertebra  124 . 
     The position of the implants  120  in the vertebra  124  can be confirmed to ensure non-perforation and proper placement of the implants  120  in the vertebra  124 . Perforation of a vertebra by the implant  120  may be undesirable for various purposes known to one skilled in the art. Thus, the icons  120   i  can be used by the user  54  to ensure that a procedure has occurred according to the plan of the user  54  or according to preferences of the user  54 . The confirmation procedure can then end in block  184 . 
     The confirmation procedure can be used to assist in determining that a selected procedure has occurred or that an implant has been positioned in the patient  14  as selected by the user  54 . According to various embodiments, a procedure can be planned based upon a pre-planned or generated planned procedure that can include inputs and substantially automatically generate a plan for a selected procedure, such as positioning the pedicle screw  120  into the vertebra  124 . 
     A program or algorithm can be executed based upon various inputs to identify a plan for achieving or performing a selected procedure. For example, as illustrated in  FIG. 9 , an algorithm can be used to identify a proposed entry point  200 , a proposed path of implantation  202 , the centerline or other anatomical feature of the vertebra  140 , an angle  204  relative to the centerline  140 , selected implant for implantation (e.g. specific dimension, model, etc.), and other appropriate features of a planned procedure. The proposed entry point  200  and the proposed path of implantation  202  can be maintained or input as a planned entry point  200  and a planned path of implantation  202 . The proposed entry point  200  and the proposed path of implantation  202  can become planned based on agreement by the user  54 , such as a surgeon or automatically. Additionally, the algorithm can be executed by a processor automatically based on a plurality of saved instructions that can be saved on an appropriate storage device or medium. 
     The plan, as illustrated on the display  66 , can be based upon preferences from the user  54 . For example, the algorithm can include accessing a database of preferences of the user  54 , such as preferred instrumentation, preferred implant models, preferred entry points, preferred angles, and other appropriate user preferences. The user preferences can be accessed by the algorithm to identify an appropriate or preferred entry point  200  for the user  54  for the specific patient  14 . For example, the user  54  may prefer to have an entry angle  204  of about 10 degrees. The database accessed by the algorithm can access the user preferences of having the approximately 10 degree entry angle and identify entry points  200  and trajectories to achieve the preferred entry angle. Accordingly, the algorithm can identify and assist in planning a procedure. 
     Preferences of the user  54  can be input or generated in a selected manner. For example, prior to a procedure the user  54  can input user preferences, such as selecting an implant, entry point, etc. The user  54  may be presented with a form and enter in the appropriate information on the form. The form may be on a monitor (to allow the user  54  to input the preferences directly) or the form can be written and the preferences can be entered by an appropriate data entry person. 
     Preferences of the user  54  can also be stored or “generated” by the planning algorithm. A procedure may be performed by the user  54  and the selected implants, entry point, angle and/or path of implantation, and other parameters can be stored by the memory device. The processor executing the planning algorithm can then access the memory device and retrieve the parameters of one or more previous similar or identical procedures. As more procedures are completed by the user  54  the planning algorithm can better predict or select proposed and/or planned entry points, implants, and other parameters for a new or subsequent procedure performed by the user  54 . Additionally, a plurality of users can access the same database of past procedures so that plans need not be based on only the experiences of one user. 
     The pre-planned procedure can also be used to assist in confirming placement of the implant  120  in the vertebra  124 . The confirmation can be used to ensure that the planned procedure has occurred and the implant, such as the pedicle screw  120 , has been positioned in the planned position. For example, the user  54  can select or generate a plan based upon preferred and optimal positioning. The second image data  154  with the superimposed models can be compared to the generated plan for confirmation. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the invention, and all such modifications are intended to be included within the scope of the invention.