Abstract:
A device and system for accessing and anchoring a patient&#39;s sentinel lymph node after a radiopharmaceutical is injected at or near a lesion site within a patient&#39;s body. The migration of and accumulation of the radiopharmaceutical in a sentinel node of the patient is monitored from outside the patient&#39;s body. The sentinel node can then be accessed through a cannula and an anchoring device may be employed to fix the location of the sentinel node. The anchoring device has at least one radially extending members which penetrate into the sentinel node. Preferably, the radially extending members are RF powered to facilitate entry into the sentinel node. With the anchor device secured to the sentinel node as a locator, subsequent procedures may be performed.

Description:
RELATED APPLICATIONS 
     This application is a divisional of copending application Ser. No. 09/727,112, filed Nov. 29, 2000, now U.S. Pat. No. 6,638,234, which is a continuation-in-part of application Ser. No. 09/146,185, filed Sep. 1, 1998, now U.S. Pat. No. 6,540,693; Ser. No. 09/159,467, filed Sep. 23, 1998, now U.S. Pat. No. 6,261,241; Ser. No. 09/356,187, filed Jul. 16, 1999, now U.S. Pat. No. 6,312,429; Ser. No. 09/477,255, filed Jan. 4, 2000, now U.S. Pat. No. 6,471,700; and Ser. No. 09/057,303, filed Apr. 8, 1998, now U.S. Pat. No. 6,331,166, which claims the benefit of provisional patent application Serial No. 60/076,973, filed Mar. 3, 1998, all of which applications and patents are hereby incorporated herein by reference in their entirety and from which priority is hereby claimed under 35 U.S.C. §§119(e) and 120. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates to the field of medical devices and methods used in the treatment of diseases such as cancer which have the ability to metastasize within a patient&#39;s body. More specifically, the invention is directed to methods and devices for locating sentinel lymph nodes associated with a lesion site within a patient&#39;s body so that the sentinel lymph nodes may thereafter be selectively removed and analyzed to determine whether disease has spread from the primary lesion site to the sentinel lymph nodes. In the case of breast cancer patients, such methods and devices may eliminate the need for complete axillary lymph node dissection in patients who do not require such invasive and debilitating procedures. 
     With regard to breast cancer patients specifically, the determination of the severity of the disease or staging is frequently determined by the level of lymph node involvement in those lymph nodes which correspond to the primary cancer lesion site in the breast. The lymph nodes which correspond to the breast area are typically located in the armpit or axilla of the patient and are connected to the breast tissue of the patient by a series of lymph ducts. Other likely areas for sentinel nodes include inframammary and submammary locations and elsewhere in the patient&#39;s chest. The sentinel lymph nodes can be in fluid communication with other surrounding lymph nodes, however, lymph drainage from the lesion site will first flow to the sentinel lymph nodes. Thereafter, lymph fluid drainage may then continue on to lymph nodes surrounding the sentinel nodes. 
     Studies have shown that by the time a typical breast cancer lesion reaches the size of 1-2 cm, the cancer will have metastasized to at least one of the sentinel lymph nodes in about one third of patients. Malignant cells break off and drain through the lymph fluid ducts to the lymph nodes and will be apparent in excised lymph nodes if the malignant cells embed in the lymph node. In patients with more advanced disease, the likelihood of spread to sentinel nodes is higher as is the likelihood of spread of the disease to the lymph nodes surrounding the sentinel lymph nodes. 
     As discussed above, when a tumor lesion is under 1-2 cm, only about ⅓ of patients will have cancer cells in the corresponding lymph nodes, and in the patients where the disease has spread to the lymph nodes, it is often confined to the sentinel lymph nodes. 
     In the past, a breast cancer patient would normally have a complete axillary lymph node dissection as an adjunct to removal of the primary lesion in the breast. Thus, the patient&#39;s entire lymph node system in the armpit area is removed and biopsied to determine the stage of the cancer and what further treatment was required. However, as discussed above, when the lesion is under 1-2 cm, two thirds of the patients had no migration of cancer cells to the lymph nodes at all, and in others, cancer had only migrated to the sentinel lymph nodes. Thus, total axillary lymph node dissection in two-thirds of the cases were unnecessary. It should be noted that total axillary lymph node dissection can be an extremely painful and debilitating procedure for patients who often suffer from severe lymph edema as a result of the body&#39;s inability to channel the flow of lymph fluid once most or all of the lymph nodes have been excised. 
     Thus there is a need for methods and devices that can be used to determine the location of sentinel lymph nodes corresponding to a patient&#39;s primary lesion site, and a reliable and noninvasive means of accessing the sentinel lymph nodes to determine whether they are involved in the disease. If the sentinel lymph nodes are determined not to have cancer cells within them, then a total axillary lymph node dissection may be avoided. 
     It has been known to use radioactive materials or radiopharmaceuticals as localizing agents which can be injected into the area of a primary lesion to monitor the flow of the materials within the patients body using a variety of detectors. Radioactive material such as Technetium 99 m, Indium 111, Iodine 123 or Iodine 125 can be injected in a fluid into the site of a primary lesion and the migration of the radioactive material through lymph ducts to the patient&#39;s corresponding sentinel lymph nodes and other surrounding lymph nodes monitored. Although techniques exist to locate the sentinel lymph nodes of a patient with such radiopharmaceutical tagging, what has been needed are methods and devices to precisely locate and access the sentinel lymph nodes of the patient in a noninvasive manner so as to minimize trauma to the patient should it be determined that a total axillary node dissection is unnecessary. 
     SUMMARY OF THE INVENTION 
     The invention is directed generally to a method and system for locating and/or accessing specific target sites within the body of a patient. More specifically, the invention is directed to a method and system for locating and accessing a sentinel lymph node of a patient which corresponds to a lesion site within the patient&#39;s body. 
     In one embodiment of the invention, a radioactive material is injected into a patient&#39;s body near a primary lesion site or other site of interest within the patient. The approximate position of a sentinel lymph node is within the patient&#39;s body is determined by detecting radiation from the radioactive material accumulated within the sentinel lymph node with a radiation detector external to the patient&#39;s body. The sentinel lymph node can then be accessed with a cannula having an RF electrode disposed on a distal end of the cannula by activating the RF electrode to ablate tissue while passing the cannula into the patient&#39;s body until the distal end of the cannula is disposed adjacent the sentinel lymph node. Thus, access to a patient&#39;s sentinel lymph node corresponding to a lesion site is achieved with minimal trauma to the patient, requiring only a hypodermic injection at the lesion site and a channel through the patient&#39;s tissue from the outside surface of the skin to the sentinel node, the channel being no larger than the outside dimension of the cannula. 
     Once the distal end of the cannula is positioned adjacent the sentinel lymph node, an anchor device can be inserted through the cannula and into the sentinel lymph node. The distal end of the anchor device can then be secured to the sentinel lymph node. Once the distal end of the anchor device is secured to the lymph node, the patient can be transferred to a surgical suite and the lymph node surgically removed with the anchor device attached thereto. The anchor device is thus used as a locator for the sentinel lymph node during the surgical procedure. 
     In some embodiments of a method of the invention, a gamma camera is used to determine the approximate position of the sentinel lymph node within the patient&#39;s body prior to accessing the sentinel lymph node with the cannula assembly. Alternatively, a hand held radiation detecting wand or the like can be used to determine the approximate position of the sentinel lymph node within the patient&#39;s body. Once the approximate position of a sentinel lymph node is known, the skin of the patient can be marked with a visible mark above the location of the sentinel lymph node prior to accessing the sentinel lymph node with the cannula. 
     A cannula suitable for use with the method discussed above can have an outer hollow shaft having an inner lumen slidingly disposed about an inner shaft having an RF electrode disposed on the distal end of the inner shaft. The inner shaft can be withdrawn from the outer hollow shaft prior to insertion of the anchor device through the inner lumen of the outer hollow shaft to access a sentinel lymph node. The RF electrode can be an arcuate shaped wire spaced distally from a distal extremity of the distal end of the cannula whereby tissue is ablated along the length of the RF electrode and displaced by the distal end of the cannula as it is advanced through the tissue. Often it is desirable to image the cannula and sentinel lymph node with an ultrasound imaging system during insertion of the cannula into the patient&#39;s body. 
     The proximity of the distal end of the cannula to a radioactive or “hot” sentinel lymph node can be determined by inserting a radiation energy detector probe through the inner lumen of the hollow outer shaft of the cannula and detecting an amount of radiation energy emanating from the tissue along the longitudinal axis of the hollow outer shaft. The hollow outer shaft or the radiation energy detector within the outer hollow shaft can be manipulated while in the patient to detect the amount of radiation energy emanating from various portions of the tissue as they pass in front of the distal end of the radiation energy detector during the manipulation. 
     The relative amount of radiation detected from the various portions of tissue adjacent the longitudinal axis of the hollow outer shaft can be compared by a visual or audio signal or the like in order for the operator of the system to determine the position of the radiation energy detector where the maximum signal strength exists. The input of the radiation energy detector can be configured so as to maximize output signal strength when a hot sentinel lymph node is disposed directly distal of the distal end of the radiation energy detector. Thus, by maximizing the output signal, the operator can determine the precise location of a hot sentinel lymph node. 
     Once it is confirmed that the distal end of the outer hollow shaft of the cannula is disposed adjacent a hot sentinel node, the distal end of an anchor device can be inserted through the inner lumen of the outer hollow shaft and secured to the sentinel lymph node. The anchor device can be secured to the sentinel node by deploying at least one extension wire from the distal end of the anchor device into the sentinel lymph node. In addition, an outer extremity of the extension wires can be configured to emit RF energy during deployment of the extension wire so as to ablate tissue adjacent a distal end of the extension wire as it is being advanced through tissue during deployment. Ablation energy activation of the distal ends of the extension wires facilitates penetration of tissue during deployment of the extension wires. 
     An embodiment of an anchor device for locating a desired portion of tissue within a patient can have an elongate shaft with a proximal and distal end. At least one extension wire is disposed at the distal end of the elongate shaft having a withdrawn configuration and a deployed configuration extending from the distal end of the shaft. The anchor device may also include a deployment actuator disposed proximal of the distal end of the elongate shaft and configured to deploy the extension wire from a retracted configuration to an extended configuration. The deployment actuator of the anchor device can be configured to both extend the extension wires and activate RF energy to the extension wires. One embodiment of an anchor device may have markings spaced at predetermined intervals to delineate the diameter of extension of the extension wires. 
     In one embodiment of an anchor device, an RF electrode is disposed on the distal end of the elongate shaft configured to ablate and penetrate tissue in a manner similar to the RF electrode on the distal end of the cannula discussed above. An RF electrode on the distal end of the elongate shaft can be in the form of an arcuate wire spaced distally from the distal extremity of the distal end of the elongate shaft and optionally may lie in substantially the same plane as the longitudinal axis of the elongate shaft. 
     A radiation energy detector for locating the position of radioactive tissue within the body of a patient suitable for use with the methods discussed above can be an elongate shaft having a proximal end, a distal end and an outer transverse dimension of the distal end of up to about 4 mm. A detector body is disposed at the distal end of the elongate shaft which is collimated to receive radiation energy at an angle of up to about 30°, preferably about 10° to about 20° from a longitudinal axis of the elongate shaft. A detector body signal processor is coupled to the detector body. A handle assembly can be disposed at the proximal end of the elongate shaft of the radiation energy detector. The length of the elongate shaft is typically configured to access to a patient&#39;s tissue through an inner lumen of a cannula and can be about 5 to about 15 cm. 
     The detector body signal processor can be configured to emit an audible signal to a user of the detector which has an amplitude which increases logarithmically in relation to an increase in the amount of radiation energy being detected. Alternatively, the detector body signal processor can produce a visual signal to a user of the detector which is proportional in amplitude to the amount of radiation energy being detected. 
     These and other advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying exemplary drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a diagrammatic view of a patient being injected with a radioactive material including monitoring of migration of the radioactive material from a lesion site to a sentinel node with a hand held radiation energy detector and a gamma camera. 
     FIG. 2 is a diagrammatic view of a medical procedure having features of the invention including ultrasonic imaging of insertion of a cannula with an RF electrode disposed on the distal end of the cannula. 
     FIG. 3 is a perspective view of a cannula with a two element RF electrode disposed on the distal end of the cannula with the RF electrode in an expanded state. 
     FIG. 4 is an elevational view in partial longitudinal section of a cannula with a two element RF electrode on the distal end in an expanded state. 
     FIG. 5 is an elevational view in partial longitudinal section of the cannula of FIG. 4 with the distal end of the inner shaft retracted into a hollow outer shaft and the RF electrode in a contracted state within the hollow outer shaft. 
     FIG. 6 is a schematic view of an outer hollow shaft of a cannula disposed within a patient with the inner shaft of the cannula withdrawn and the distal end of the outer hollow shaft adjacent a sentinel lymph node. A radiation energy detector probe is positioned for insertion into the outer hollow shaft of the cannula. 
     FIG. 7 is an elevational view in partial section of a radiation energy detector disposed within an outer hollow shaft of a cannula with the distal end of the radiation energy detector probe disposed adjacent a first sentinel lymph node and a second sentinel lymph node with the longitudinal axis of the outer hollow shaft and radiation energy detector probe substantially aligned with the center of the first sentinel lymph node. 
     FIG. 8 is a diagrammatic view of the distal end of a radiation energy detector probe disposed adjacent a first and second sentinel lymph node with the longitudinal axis of the detector probe substantially aligned with the center of the first sentinel lymph node and a phantom outline of the distal end of the radiation energy detector probe wherein the longitudinal axis thereof is substantially aligned with the center of the second sentinel lymph node. 
     FIG. 9 is a perspective view of an anchor device having features of the invention. 
     FIG. 10 is an elevational view in partial longitudinal section of an anchor device having features of the invention, wherein the extension wires at the distal end of the anchor device are in a retracted position. 
     FIG. 11 is an elevational view in partial section of the anchor device of FIG. 10 with the extension wires in an expanded position extending radially outward from a longitudinal axis of the anchor device. 
     FIG. 12 is a transverse cross sectional view of a handle assembly of the anchor device of FIG. 11 taken along lines  12 — 12  of FIG.  11 . 
     FIG. 13 is a transverse cross sectional view of the elongate shaft of the anchor device of FIG. 11 taken along lines  13 — 13  in FIG.  11 . 
     FIG. 14 is an end view in partial transverse cross section of the distal end of the anchor device of FIG. 11 taken along lines  14 — 14  of FIG.  11 . 
     FIG. 15 is a top view of the actuator switch of the anchor device of FIG. 11 in a fully forward distal position corresponding to full extension of the extension wires in an outward radial direction. 
     FIG. 16 is a schematic view of an anchor device being inserted into an outer hollow shaft of a cannula the distal end of which is disposed adjacent a sentinel lymph node. 
     FIG. 17 is an enlarged view in partial longitudinal section of the anchor device of FIG. 16 wherein the distal end of the anchor device is disposed within a sentinel lymph node of the patient with the extension wires in a retracted position. 
     FIG. 18 is an enlarged view in partial section of the anchor device of FIG. 16 wherein the distal end of the anchor device is disposed within a sentinel lymph node of the patient with the extension wires in an extended position wherein the extension wires have pierced and are mechanically secured to the sentinel lymph node. 
     FIG. 19 is a schematic view of an outer hollow shaft of a cannula and a handle assembly of an anchor device being removed from the patient proximally with the distal shaft of the anchor device remaining within the patient with the distal end of the anchor device secured to the sentinel lymph node with the extension wires. 
     FIG. 20 is an elevational view in partial section of an anchor device having features of the invention including extension wires which are radially extendable from the distal end of the anchor device, an expandable RF electrode on the distal end of the anchor device and a radiation detector probe disposed within an inner lumen of the anchor device and which is optionally axially moveable within the inner lumen of the anchor device. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 illustrates a patient  10  being injected with a radioactive material or radiopharmaceutical via a syringe  11  having a hypodermic needle  12  at a lesion site  13  within the patient&#39;s breast  14 . Monitoring of migration of the radiopharmaceutical  15  from the injection location  16  in or near the lesion site  13  to a sentinel node  17  is carried out with a hand held radiation energy detector  21  or alternatively a gamma camera  22 . The approximate position of the sentinel lymph node  17  is determined by detecting radiation from the radioactive material  15  accumulated within the sentinel lymph node  17  with the hand held radiation detector  21  or the gamma camera  22 . Radioactive material  15  such as Technetium 99 m, Indium 111, Iodine 123 or Iodine 125 can be injected in a fluid into the site of a primary lesion  13  and the migration of the radioactive material through lymph ducts to the patient&#39;s corresponding sentinel lymph nodes  17  and other surrounding lymph nodes observed. 
     By correctly timing the observation of the radiation energy signals coming from the patient&#39;s body after injection of the radioactive substance  15 , it is possible to locate the sentinel lymph nodes  17  corresponding to the lesion site  13 . The sentinel lymph nodes  17  corresponding to a given lesion site  13  or other site of interest within a patient&#39;s body are those lymph nodes to which lymph fluid emanating from the lesion site drains to first. As discussed above, the lymph nodes which correspond to the breast area are typically located in the armpit of the patient and are connected to the breast tissue  14  of the patient  10  by a series of lymph ducts. Lymph nodes of the axilla are approximately 1 to 2 cm in diameter and are approximately 1 to 5 inches deep in the tissue of the armpit area. 
     The sentinel lymph nodes  17  can be in fluid communication with other surrounding lymph nodes, however, lymph drainage from the lesion site  13  will first flow to the sentinel lymph nodes  17 . Thereafter, lymph fluid drainage may then continue on to lymph nodes surrounding the sentinel nodes  17 . Therefore, if a patient  10  is monitored or observed with a hand held radiation detector  21  or gamma camera  22  after the radioactive material  15  has migrated through the lymph ducts to the sentinel lymph nodes  17  but prior to dispersion of the radioactive material to the lymph nodes surrounding the sentinel nodes, an accumulation of radioactive material  15  will be observed in the sentinel lymph nodes  17 . These hot sentinel nodes  17  will be clearly distinguishable from surrounding non-radioactive lymph nodes using radiation energy detectors from outside the patient&#39;s body  10 , thus indicating an approximate position of nodes  17  in a non-invasive manner. 
     The hand held radiation energy detector  21  has a hand held probe  23  with a proximal end  24  and a distal end  25 , a control and display unit  26 , and an electrical conduit or cable  27  disposed between the control unit  26  and the hand held probe  23 . The control unit  26  can produce an audible or visual output that is commensurate with the amplitude of radiation energy signal being received at the distal end  25  of the hand held probe  23 . Typically, the hand held probe  23  will only detect radiation energy which impinges in a proximal direction upon the distal end  25  of the hand held probe  23  at some predetermined angle with respect to a longitudinal axis  31  of the hand held probe  23 . Thus, by manipulating the location and direction of the distal end  25  of the hand held probe  23 , the approximate location of the hot sentinel lymph nodes  17  within the patient  10  can be determined by maximizing the audio or visual signal generated by the control and display unit  26 . 
     The gamma camera  22  shown in FIG. 1 has a receiver unit  33 , a control unit  34  and a display,  35 . Radiation energy emitted from the radioactive material  15  injected into the patient  10  travels through the tissue of the patient  10  to the receiver unit  33  which then generates and electrical signal at a location corresponding to the location of the radioactive material source in the patient  10 . The signal or hits from the radiation energy which impinges on the receiver  33  can be accumulated or stored such that the display  35  will show all hits received from the various portions of the receiver  33 . In this way, the relative location of radioactive material  15  in the patient&#39;s body  10  can be seen on the display and particularly locations in the patient&#39;s body  10  where radioactive material  15  has accumulated. The skin of the patient  10  can be marked with a visible mark above the location of the sentinel lymph node  17  to indicate the approximate position of the sentinel node  17  for future reference during the procedure. 
     Once the approximate position of the sentinel lymph nodes  17  of a patient  10  corresponding to a primary lesion site  13  is determined, an access device  36  may be used to breach tissue over the lymph nodes. This allows locating the sentinel nodes  17  with greater precision. FIG. 2 shows ultrasonic imaging of insertion of an access device  36  consisting of a cannula  37  having an RF electrode  41  disposed on the distal end  42  of the cannula  37 , an RF energy generator  43  in electrical communication with the RF electrode  41 , a cannula handle assembly  44  at a proximal end  45  of the cannula  37  and a ground pad  46  secured to and in electrical communication with the patient&#39;s body  10  and the RF generator  43 . The sentinel lymph node  17  is accessed by passing the cannula  37  with the RF electrode  41  energized to emit RF energy therefrom into the patient&#39;s body  10  until the distal end  42  of the cannula  37  is disposed adjacent the sentinel lymph node  17 . 
     The RF generator  43  for the RF electrode  41  can be any of a variety of standard electrosurgical units generating radiofrequency energy in a range of about 300 to about 6,000 kHz, specifically, about 350 to about 1,000 kHz. Power output for the RF generator  43  can be about 25 to about 150 watts, preferably about 75 to about 125 watts. The RF electrode  41  can be made of a variety of materials, including stainless steel, tungsten, nitinol and the like. The RF electrode material may have a cross section that is round, rectangular, oval or any other suitable configuration and generally has a transverse dimension of about 0.001 to about 0.015 inch, specifically about 0.006 to about 0.010 inch. 
     Because large arteries and nerves are generally located in the same area as the axillary lymph nodes of a patient  10  and could be compromised without an accurate and noninvasive access device  36 , ultrasonic imaging can be used while the cannula  37  is being inserted into the patient  10 . An ultrasonic imaging system  47  having a transducer  51 , transducer cable  52 , control unit  53  and display  54  is shown in FIG.  2 . The two sentinel lymph nodes  17  are imaged on the display  54 . The relative location of the target sentinel lymph node  17  and cannula  37  can be imaged and monitored during insertion of the cannula  37  to ensure accurate placement of the cannula and avoidance of sensitive anatomical features such as nerves and arteries. Because RF tissue ablation frequently interferes with ultrasonic imaging and the like, it may be desirable to use a system for reduction of such interference such as is taught by copending U.S. patent application Ser. No. 09/527,868, by Dabney et al., filed Mar. 17, 2000, which is hereby incorporated by reference herein in its entirety. 
     Referring to FIGS. 3-5 the cannula  37  is shown with a two element RF electrode  41  disposed on the distal end  42  of the cannula  37 . A outer hollow shaft  55  having an inner lumen  56  is slidingly disposed about an inner shaft  57  having the RF electrode  41  disposed on the distal end  61  of the inner shaft  57 . The RF electrode  41  has a first electrode element  62  and a second electrode element  63  which overlap at the intersection with the longitudinal axis  64  of the cannula  37  extending from the distal end  42 . This arrangement allows for the first and second electrode elements  62  and  63  to be expandable to an outer transverse dimension equal to or slightly greater than the circumference of the outer hollow shaft  55 . This enables easy insertion of the cannula assembly  37  into the patient  10  as the RF electrode  41  is activated and ablates tissue. The expandability and retractability of the RF electrode  41  allows the inner shaft  57  to be withdrawn from the outer hollow shaft  55  prior to insertion to provide access through the outer hollow shaft  55  to a sentinel lymph node  17  or other tissue area of interest within a patient  10 . 
     The RF electrode  41  is an arcuate shaped wire  65  spaced distally from a distal extremity  66  of the distal end  42  of the cannula  37 . When the electrode  41  is activated with RF energy, tissue is ablated along the length of the RF electrode  41  and displaced by the distal end  42  of the cannula  37  as it is advanced through the tissue. FIG. 4 shows the RF electrode  41  on the distal end  42  of the cannula  37  in an expanded state in which the transverse dimension of the RF electrode  41  as a whole is greater than the outer diameter of the outer hollow shaft  55 . In FIG. 5, the distal end  61  of the inner shaft  57  of the cannula  37  is withdrawn into the inner lumen  56  of the hollow outer shaft  55  and the RF electrode  41  is in a contracted state within the inner lumen hollow outer shaft. 
     FIG. 6 shows an outer hollow shaft  55  of a cannula  37  disposed within a patient  10  with the inner shaft  57  of the cannula  37  withdrawn and the distal end  67  of the outer hollow shaft  55  adjacent a sentinel lymph node  17 . A radiation energy detector  71  having a signal processor unit  72 , a handle assembly  73  and a radiation detector probe  74  with a proximal end  75  and distal end  76  is positioned to have the distal end  76  of the radiation energy detector probe  74  inserted into the inner lumen  56  of the outer hollow shaft  55 . A cable  77  is in communication with the signal processor unit  72  and a proximal end  81  of the handle assembly  73 . 
     In FIG. 7, the radiation energy detector probe  74  is shown disposed within the outer hollow shaft  55  of the cannula  37 . The distal end  76  of the radiation energy detector probe  74  is disposed adjacent a first sentinel lymph node  82  and a second sentinel lymph node  83  with a longitudinal axis  84  of the outer hollow shaft  55  and longitudinal axis  85  of the radiation energy detector probe  74  substantially aligned with the center  86  of the first sentinel lymph node  82 . The radiation energy detector probe  74  detects radiation energy emanating from the tissue along the longitudinal axis  85  of the probe  74  in a proximal direction relative to the probe. The hollow outer shaft  55  or the radiation energy detector probe  74  within the outer hollow shaft  55  can be manipulated, as shown in FIG. 8, while in the patient  10  to detect the amount of radiation energy emanating from various portions of the tissue as they pass in front of the distal end  76  of the radiation energy detector probe  74  during the manipulation. 
     The amount of radiation detected from the various portions of tissue adjacent the longitudinal axis  84  of the hollow outer shaft  55  can be compared by observation of a visual or audio signal or the like generated by the signal processor unit  72  in order for the operator of the system to determine the position of the radiation energy detector probe  74  where the maximum signal strength exists. The input of the radiation energy detector probe  74  at the distal end  76  of the probe  74  can be configured or collimated so as to maximize output signal strength when a sentinel lymph node  17  emitting a relatively large amount of radiation (“hot” sentinel lymph node) is disposed directly distal of the distal end  76  of the radiation energy detector probe  74 . Thus, by maximizing the output signal from the signal processor unit  72 , the operator can determine the precise location of a hot sentinel lymph node  17  and effectively discriminate surrounding nonradioactive tissue and non-radioactive nodes. 
     In FIG. 8, the longitudinal axis  85  of the detector probe  74  is substantially aligned with the center  86  of the first sentinel lymph node  82 . A phantom outline of the distal end of the radiation energy detector probe is also shown substantially aligned with the center  91  of the second sentinel lymph node  92  after manipulation of the distal end  76  of the radiation energy detector probe  74  from the proximal end  75  of the radiation energy detector probe  74  or the proximal end  93  of the outer hollow shaft  55  of the cannula  37 . The diameter of the elongate probe  74  of the radiation energy detector distal end can be about 1 to about 6 mm, specifically about 3 to about 5 mm, and more specifically about 4.0 to about 4.4 mm. 
     A detector body (not shown) is disposed within the distal end  76  of the elongate radiation energy detector probe  74  which is collimated to receive radiation energy at an angle of up to about 30°, preferably about 10° to about 20°, from a longitudinal axis  85  of the elongate radiation energy detector probe. The detector body can be designed to encompass the radiation emitted from a 1 cm node at a distance of 1 cm. The detector body can be configured or collimated to have enhanced reception of radiation energy from the distal end as opposed to side impingement of radiation energy. The detector body is coupled by the cable  77  to the signal processor unit  72 . The detector body can be configured to specifically detect gamma radiation or any other suitable form of radiation energy including alpha or beta radiation. The handle assembly  73  of the radiation energy detector  71  can have a preamplifier within it to increase the signal from the detector body to the signal processor unit  72 . The handle  73  typically has a diameter or transverse dimension of about 25-30 mm. The length of the radiation energy detector probe  74  is typically configured to access to a patient&#39;s tissue through an inner lumen of a cannula and can be about 5 to about 15 cm. 
     The signal processor unit  72  of the radiation energy detector  71  can be configured to emit an audible signal to a user of the detector which has an amplitude which increases logarithmically in relation to an increase in the amount of radiation energy being detected. Alternatively, the detector body signal processor unit  72  can produce a visual signal to a user of the detector which is proportional in amplitude to the amount of radiation energy being detected. The signal processor  72  has a display  95  with a digital readout of counts per second and total counts for given time period. The radiation energy detector  71  can typically detect radiation at useable levels from a hot lymph node from a distance of about 10 to about 12 cm, but is most accurate at a distance of about 2 to about 3 cm. 
     Referring to FIGS. 9-19, an anchor device  100  and use thereof is shown. The anchor device  100  has a housing  101 , an inner conductor  102 , a main shaft  103  disposed within an inner lumen  104  of the inner conductor  102 , an actuator  105  coupled to the inner conductor  102  for extending the extension wires  106  and an RF energy generator  107  switchably coupled to the inner conductor  102  and elongate shaft  111  with a proximal end  112  and distal end  113 . At least one extension wire  106  is disposed within the distal end  113  of the elongate shaft  111  coupled to a distal end  114  of the inner conductor  102  and having a withdrawn configuration and a deployed configuration extending radially from the distal end  113  of the shaft  111 , or in some other suitable direction. A deployment actuator  105  is disposed proximal of the distal end  113  of the elongate shaft  111  and configured to deploy the extension wire  106  from a retracted configuration to an extended configuration. 
     Markings  115  on the housing  101 , as shown in FIG. 15, may be spaced at predetermined intervals to delineate the diameter of extension of the at least one extension wire  106  by movement of actuator  105 . As shown in FIG. 16, a first electrical conductor  116  can be electrically coupled to the inner conductor  102  and the RF energy generator  107  and a second electrical conductor  117  electrically coupled to the patient  121  as a ground plate  122  for the RF energy generator  107 . RF energy may be applied to the extension wires during deployment and extension thereof to aid in the advancement thereof through tissue. However, if RF energy is to be applied, the extension wires should be insulated along their lengths except for the distal tips thereof. The first electrical conductor  116  can be coupled to the extension wires  106  at the proximal end of the shaft  111  with a detachable coupler  123 . 
     The anchor device  100  is generally inserted through the outer hollow shaft  124  of a cannula  125  and into a sentinel lymph node  126 . The distal end  127  of the anchor device  100  is then secured to the sentinel lymph node  126 . Once the distal end  127  of the anchor device  100  is secured to the lymph node  126 , the patient  121  can be transferred to a surgical suite and the lymph node  126  surgically removed with the anchor device  100  attached thereto serving as a locating device. 
     In the embodiment of the anchor device shown in FIGS. 9-19, the distal end  127  of the anchor device  100  can be secured to the sentinel lymph node  126  by deploying at least one extension wire  106  from the distal end  127  of the anchor device  100  into the sentinel lymph node  126  as shown in FIG.  18 . In addition, an outer extremity  131  of the extension wires  106  can be configured to emit RF energy during deployment of the extension wires so as to ablate tissue adjacent the outer extremities  131  of the extension wires  106  to facilitate advancement through tissue during deployment. Radial extension of the extension wires  106  from the anchor device  100  can be from about 1 to about 30 mm, specifically about 3 to about 25 mm, and more specifically about 5 to about 12 mm when deployed fully. 
     FIG. 10 shows the anchor device  100  where the extension wires  106  at the distal end  127  of the anchor device  100  are in a retracted position. A spring loaded electrical contact  132  is disposed within the coupler  123  disposed on the distal end  133  of first conductor  116 . The electrical contact  132  is slidingly and electrically coupled to a distal end which is secured to and in electrical communication with a proximal end  134  of the inner conductor  102 . The first conductor  116  is able to slide within the spring loaded contact  132  maintaining an electrical path between conductor  116  and inner conductor  102  while allowing axial translation of the inner conductor  102  relative to the coupler  123  and housing  101 . 
     Actuator switch  105  is mechanically coupled to inner conductor  102  and slidingly engaged in a slot  135  in the housing  101  with an abutment  136  extending radially from the slot  135  in the housing  101  to facilitate axial movement by the operator of the anchor device  100 . In FIG. 10 the actuator switch  105  and abutment  136  are in the most proximal position within the slot  135  which corresponds to the radially retracted position of the extension wires  106 . FIG. 11 shows the extension wires  106  in a radially expanded position extending radially outward from a longitudinal axis  137  of the anchor device  100  with the actuator switch  105  in its corresponding most distal forward position. 
     FIG. 15 shows a top view of the actuator switch  105  of the anchor device  100  in a fully forward distal position corresponding to full extension of the extension wires  106  in an outward radial direction as shown in FIG.  10 . Also in FIG. 15 the axial markings  115  can be more clearly seen with numerical designations which may correspond to the diameter or radius of the extension wires  106  at the distal end  127  of the anchor device  100 . In FIG. 16 the anchor device  100  is being inserted into an outer hollow shaft  124  of a cannula  125  the distal end  141  of which is disposed adjacent a sentinel lymph node  126 . The inner conductor  102  of the anchor device  100  is electrically coupled to a conductor  116  which is in turn electrically coupled to the RF generator  107 . A ground pad  122  is in electrical contact with the patient  121  and electrically coupled to the RF generator  107  with a second conductor  117 . 
     FIG. 17 shows the elongate shaft  111  of the anchor device  100  disposed within an inner lumen  142  of the hollow outer shaft  124  of the cannula  125 . The distal end  127  of the anchor device  100  disposed within a sentinel lymph node  126  in the tissue of the patient  121  with the extension wires  106  in a retracted position. In FIG. 18, the extension wires  106  of the anchor device  100  have been extended into the sentinel lymph node  126  and mechanically secured thereto. In FIG. 19, the outer hollow shaft  124  of the cannula  125  and housing  101  of the anchor device  100  are being removed proximally from the patient  121 . The elongate shaft  111  of the anchor device  100  remains within the patient  121  with the distal end  127  of the anchor device  100  secured to the sentinel lymph node  126  with the extension wires  106  in an extended position. Thereafter, the patient  121  may be taken to surgery to have the lesion excised or otherwise treated with the elongate shaft  111  of the anchor device  100  serving as a positive location means during the procedure. 
     In use during a typical procedure, radioactive material  15  is injected into a patient&#39;s body  10  near a primary lesion site  15  or other site of interest within the patient  10 . The approximate position of a sentinel lymph node  17  within the patient&#39;s body  10  is determined by detecting radiation from the radioactive material  15  accumulated within the sentinel lymph node  17  with a radiation detector  21  or  22  external to the patient&#39;s body  10 . The sentinel lymph node  17  can then be accessed with a cannula  37  having an RF electrode  41  disposed on a distal end  42  of the cannula  37  by activating the RF electrode to ablate tissue while passing the cannula into the patient&#39;s body  10  until the distal end  42  of the cannula  37  is disposed adjacent the sentinel lymph node  17 . 
     Once the distal end  42  of the cannula  37  is positioned adjacent the sentinel lymph node  17 , the proximity of the distal end  42  of the cannula  37  to the sentinel lymph node  17  can be optimized by inserting a radiation energy detector probe  74  into an inner lumen of a hollow outer shaft  55  of the cannula  37  and manipulating a distal end  76  of the radiation energy detector probe  74  so as to positively identify the position of the targeted sentinel node  17  by maximizing radiation energy received by the radiation energy probe from the targeted sentinel node. 
     An anchor device  100  can then be inserted through the cannula  37  and into the sentinel lymph node  17 . The distal end  127  of the anchor device  100  can then be secured to the sentinel lymph node  17 . Once the distal end  127  of the anchor device  100  is secured to the lymph node  17 , the patient  10  can be transferred to a surgical suite and the lymph node  17  surgically removed with the anchor device  100  or a portion thereof attached thereto. 
     Referring to FIG. 20, an alternative embodiment of an anchor device  150  is shown having features of the invention. The anchor device  150  has extension wires  151  which are radially extendable from the distal end  152  of the anchor device  150 , an expandable RF electrode  153  on the distal end  152  of an elongate shaft  154  of the anchor device  150  and a radiation detector probe  155  which is disposed within an inner lumen  156  of the anchor device  150  and which is optionally axially moveable within the inner lumen  156  of the anchor device  150 . 
     The RF electrode  153  is configured to ablate and penetrate tissue in a manner similar to the RF electrode  41  on the distal end  42  of the cannula  41   37  discussed above. The RF electrode  153  on the distal end  152  of the elongate shaft  154  is an arcuate wire having two separate electrode elements, a first electrode element  157  and a second electrode element  158 , spaced distally from a distal extremity  161  of the distal end  152  of the elongate shaft  154 . The RF electrode  153  of the embodiment shown lies in substantially the same plane as a longitudinal axis  162  of the elongate shaft  154  of the anchor device  150 . 
     In use during a typical procedure for this embodiment, radioactive material is injected into a patient&#39;s body near a primary lesion site or other site of interest within the patient. The approximate position of a sentinel lymph node within the patient&#39;s body is determined by detecting radiation from the radioactive material accumulated within the sentinel lymph node with a radiation detector external to the patient&#39;s body. The sentinel lymph node (shown in phantom in FIG. 20) can then be accessed with the anchor device  150  having the RF electrode  153  disposed on a distal end  152  of the anchor device  150  by activating the RF electrode  153  to ablate tissue while passing the distal end  152  of the anchor device into the patient&#39;s body until the distal end  152  of the anchor device is disposed adjacent the sentinel lymph node. 
     Once the distal end  152  of the anchor device  150  is positioned adjacent the sentinel lymph node, the proximity of the distal end  152  of the anchor device to the sentinel lymph node can be optimized by manipulating the distal end of the anchor device so as to maximize signal output by the radiation energy detector  155  within the anchor device  150 . The distal end  152  of the anchor device  150  can be secured to the sentinel lymph node by the extension of extension wires  151  into the node. Once the distal end  152  of the anchor device  150  is secured to the lymph node, the patient can be transferred to a surgical suite and the lymph node surgically removed with the anchor device attached thereto. 
     While particular forms of the invention have been illustrated and described, it should be apparent that various modifications can be made without departing from the spirit and scope of the invention. Accordingly, it is not intended that the invention be limited, except as by the appended claims.