WO2007117478A2

WO2007117478A2 - Marking and scanning surical targets in vivo

Info

Publication number: WO2007117478A2
Application number: PCT/US2007/008331
Authority: WO
Inventors: Robert J. Petcavich; Murray Reicher
Original assignee: Health Beacons, Inc.
Priority date: 2006-04-05
Filing date: 2007-04-05
Publication date: 2007-10-18
Also published as: WO2007117478A3

Abstract

A method for use in surgically removing suspect tissue, diseased organs and/or foreign objects from a body, resides in implantation within the body proximate the suspect tissue or object prior to surgery of one or more passive integrated transponder tags and, at the time of and/or during surgery, scanning of the body with a radio frequency scanner or reader that activates the tag or tags and provides the surgeon with one or more signals indicative of the location and identification of each of the tags. A grid dip meter is employed during surgery to pin-point the location of the tags, thereby to aid the surgeon in performance of the surgery. Verification of the procedure is obtained following surgery by scanning the site for absence of the tags and/or by scanning the excised tissue for presence of the tags.

Description

SURGICAL PROCEDURES

Cross-Reference

This application claims the benefit of co-pending U.S. Provisional Application No. 60/789,124, filed April 5, 2006, entitled "Method of Locating Tissue or Foreign Objects during Surgery Using Passive Transponders and a Grid Dip Oscillator". This application is a continuation-in-part of co-pending PCT International Application No. PCT/US2007/02313, filed January 25, 2007, which claims the benefit of U.S. Provisional Application No. 60/761,851, filed January 25, 2006, entitled "Method of Locating Tissue or Foreign Objects Using Implantable Removable Transponders".

Field of the Invention

This invention relates to surgery performed on the bodies of humans and animals for removal of suspect tissue, such as cancer, malignancies, tumors and diseased organs, and for removal of foreign objects, such as bullets- The invention is concerned with the identification of a surgical site and the location of suspect tissue for the benefit of an operating surgeon or veterinarian. More particularly, this invention relates to improved methodology to identify the region of surgical interest and the location of tissue that is to be removed by surgery, and subsequent verification of removal of such tissue.

SUBSTITUTE SHEET (RULE 26) l Background

Despite the advances made in technologies such as medical imaging to

assist the physician in early stage diagnosis and treatment of patients with possible atypical tissue such as cancer, it is often necessary to sample difficult to reach organs or tissue lesions by biopsy to confirm the presence or absence of abnormalities or disease.

One disease for which biopsy is a critical tool is breast cancer. This affliction is responsible for 18% of all cancer deaths in women and is the leading cause of death among women aged 40 to 55.

In the detection and treatment of breast cancer, there are two general classes of biopsy: the minimally invasive percutaneous biopsy and the more invasive surgical, or "open", biopsy.

Percutaneous biopsies include the use of fine needles or larger diameter core needles. They may be used on palpable lesions or under stereotactic x-ray, ultrasonic, or other guidance techniques for nonpalpable lesions and microcalcifications (which are often precursors to metastatic cell growth). In the fine needle biopsy, a physician inserts a small needle directly into the lesion and obtains a few cells with a syringe. Not only does this technique require multiple samples, but each sample is difficult for the cytologist to analyze as the specimen cells are isolated outside the context of healthy surrounding tissue.

Larger samples may be removed via core biopsy. This class of procedures is typically performed under x-ray guidance in which a needle is inserted into the tissue to drill a core that is removed via vacuum aspiration, etc. Typically four

to five samples are taken from the body. Examples of such biopsy methods include the

MAMMOTOME vacuum aspiration system by Johnson & Johnson of New Brunswick, N.J., the ABBI system by United States Surgical Corporation, Norwalk, Conn., and the STTESELECT system by ϊmagyn, Inc. of Irvine, Calif.

Open biopsies are advisable when suspicious lumps should be removed in their entirety or when core needle biopsies do not render sufficient information about the nature of the lesion. One such type of open biopsy is the wire localization

biopsy. After multiple mammograms are taken of the breast, the images are

analyzed to determine the location of the suspect lesions. Next, after a local anesthetic

is administered, and with the aid of an ultrasound, mammographic or other imaging system, a radiologist inserts a small needle into the breast and passes the needle to the suspect tissue. The radiologist then passes a wire with a hook on its end through the needle and positions the hook so that the end of the wire is distal to the suspect tissue. A final image is taken of the lesion with the accompanying wire in place, and the radiologist marks the film for x-ray indicators of a suspicious lesion that should be removed. The wire is left in the tissue and the patient is taken to the operating room, where the suspect tissue is removed by a surgeon. The removed tissue is then sent from the operating room to a radiologist to determine, via x-ray examination, if the tissue contains the x-ray indicators and if the size and borders are adequate to confirm the removal of all suspicious tissue. Examples of such wire markers are known in the art. See, e.g., the following patents, each of which is incorporated herein by reference: U.S. Pat. No. 5,158,084 to Ghiatas, U.S. Pat. No. 5,409,004 to Sloan, U.S. Pat. No. 5,059,197 to

Urie et al., U.S. Pat. No. 5,197,482 to Rank, U.S. Pat. No. 5,221,269 to Miller et al., and U.S. Pat. No. 4,592,356 to Gutierrez. Other similar devices are described in U.S. Pat. No. 5,989,265 to Bouquet De La Joliniere et al. and U.S. Pat. No. 5,709,697 to Ratcliff et al., each incorporated herein by reference.

Despite the advantages of wire localization techniques to locate the suspect tissue for the surgeon, they have a number of severe limitations. If such wire is inaccurately placed, it cannot be removed except by surgical excision. For these reasons, the radiologist must mark the x-ray film or

prepare notations providing instructions to the surgeon on how to find the lesion as a backup to confirm the proper location of the needle.

Because the distal tip of the wire might have been placed anywhere from the very center of the lesion to quite some distance away from the lesion, the surgeon must guide a scalpel along the wire and rely upon the skill of the radiologist and the marked x-ray film in the excision procedure. Even if the wire has been properly placed in the lesion and the x-ray film clearly shows the lesion boundary or margin, the surgeon often cannot see the tip of the wire (given the surrounding tissue) so she must remove a larger portion of tissue than is necessary to ensure proper excision.

If the lesion is not found at the end of the wire, the surgeon ends up cutting or removing non-afflicted tissue without removing the lesion. Also, if the tip of the wire penetrates the lesion, the surgeon may sever the lesion in cutting through the tissue along the wire to reach its end. Tn the latter case, a re-excision may be

necessary to remove the entire lesion.

Finally, post-excision re-imaging is almost always performed prior to closing the surgical field to ensure that the targeted tissue volume containing the

suspect lesion is removed. This requires radiological imaging in the operating room or transport of a specimen outside the operating room to an imagining facility or suite to radiographically confirm excision of the targeted tissue.

When marking lesions in the breast, two paddles are typically used to compress and stabilize the breast for placement of the wire. Upon release of the breast

from compression, the wire marker can dislodge or migrate to another position away from the suspect tissue. It may also migrate while the patient awaits surgery. In

addition, the fact that the breast is in an uncompressed- .state during the excision procedure renders a different view of the lesion with respect to the healthy tissue.

Various tissue localization systems have been developed to minimize inadvertent migration of the wire by configuring the wire with a bend or hook, such as

Ghiatas et al., discussed above, U.S. Pat. No. 5,011,473 to Gatturna, and the

MAMMALOK needle/wire localizer sold by Mitek Surgical Products, Inc., Dedham,

Mass. Even if a wire does not migrate after placement, the surgeon cannot determine the shortest path to the lesion; rather, the surgeon must always follow the wire, which is rarely the more cosmetically desirable path to the lesion (such as a circumareolar approach).

Because the distal tip of the wire is often placed in the center of the suspect tissue, a problem known as "track seeding" can occur in which cancerous or precancerous cells disturbed by the wire are distributed to unaffected tissue during the procedure.

Additionally, the use of a localization wire marker presents logistical problems. After placement, the wire protrudes from the body. It is almost always necessary for the patient to proceed with the surgical removal of the lesion

immediately after wire placement to minimize the chance of infection, wire breakage or disturbance, etc. Thus, when using a hookwire, the location procedure must be scheduled immediately prior to surgery, requiring coordination of scheduling between a radiologist and a surgeon, and between an image suite and a surgical suite. When using a wire, the surgeon is generally committed to following the same surgical approach that the radiologists used to place the wire. Sometimes, the optimal skin entry position and angle of the wire that is optimal for imaging i placement is not the

ideal skin entry position for the surgeon and the cosmetic outcome for the patient.

Metallic tags, such as titanium clips, may similarly be implanted in a patient's body to mark the location of suspect tissue, particularly rumors, for the benefit of an operating surgeon or veterinarian. Though highly beneficial, metallic markers suffer many of the same limitations as hookwires. In particular, metallic markers require radiological imagining in the operating room and/or the transport of specimen's outside of the operating room to an imagining suite to radiographically confirm that the marker is in the resected lesion.

What is needed is tissues, organ and object locating device that may be accurately yet removably placed into a target area or surgical site, i.e., a region of tissue that contains suspect tissues, preferably without penetrating or disturbing that volume of tissue. Such a device should reliably define the location and volume of tissue to be removed without the risk of inadvertent migration of the device.

Furthermore, a need remains to improve the interaction between the radiologist and the surgeon, to eliminate the need for post-excision x-rays and re-excision, to reduce the overall time for the procedure, and to allow a surgeon to select the shortest or most cosmetically desirable path to the suspect tissue.

Summary of the Invention

It is an object of the present invention to provide tissue locating methodology fulfilling the above-enumerated needs.

Another object of the invention is to provide a method of and select

apparatus for enabling a surgeon performing an operation to identify and locate suspect tissue, organs and objects in a body, usually from the exterior of the body, remotely of the suspect tissue or object. It is in particular an object of the invention to provide improved methodology and select apparatus for identifying and locating suspect tissues, organs and objects in a body utilizing microencapulation and radio frequency technologies.

More particularly, the invention resides in a method of use of microencapsulated, implantable, passive integrated transponder (PIT) elements or tags, a device, such for example as a thin needle syringe or deployment device, for implanting one or more of the miniature PIT tags proximate a target organ, tissue or object, and a radio frequency probe, scanner or reader manipulated externally of the body for locating and identifying the implanted tag or tags and thus the location and

volume of tissue to be excised by the surgeon.

The locator PIT element or tag includes a transponder that is passive

until energized by radio frequency energy and a pre-recorded memory chip containing information and/or signals that are emitted by the transponder when it is energized. The element is partially or totally radiopaque and shaped to penetrate tissue so that at least a portion of the locator element when implanted in a body defines a tissue border along a first path. The tissue border defines a volume of tissue for subsequent excision along the border, and contains a target region that is substantially bounded by or in proximity to the PIT locator element.

The invention involves placing removable locator elements in tissue. This. is accomplished by penetrating through tissue at a first site to create a port or a pathway for accessing a targeted tissue volume to be excised, inserting a deployment needle or device into the area of tissue of interest and using the needle or device to deploy and implant the PIT element. The tissue volume will contain a target region that is substantially near but not penetrated by the locator element.

The PIT locator element may be placed under x-ray guidance, stereotactic x-ray guidance, ultrasonic guidance, magnetic resonance imaging guidance, and the like. Target region visibility may be enhanced by, for example, the placement or injection of an echogenic substance, such as collagen, hydrogels, microspheres, or other like biocompatible materials, or by the injection of air or other biocompatible gases or contrast agents. Second, third and even more locator PIT elements or tags may be advanced through the distal end of the deployment needle or device to penetrate tissue

so that at least portions thereof further define the tissue border along second, third and/or more paths. The additional paths may be parallel or non-parallel to the first

path and may be angularly displaced with respect thereto at any angle or angles the radiologist desires.

The method includes the step of excising the tissue volume defined by the one or more PIT locator elements. This may be accomplished by surgically accessing the locator element and cutting tissue substantially along the surface of the locator element opposite the surface that is disposed immediately adjacent the tissue volume.

The method includes the use of an external hand held or stationary radio frequency emitting probe, scanner or reader that locates the PIT element, imparts electrical power to the PIT element and causes the element to transmit back to the antenna probe a signal of its location and an unique identification number assigned to the tag to verify the identity of the patient and the surgical procedure to be performed.

At the conclusion of or following surgery, but before closing the surgical field or incision, the radio frequency probe or scanner is again employed to scan one or the other or both of the surgical field, to determine the absence therefrom of the PIT tag or tags, and the excised tissue, to determine the presence therein of the tag or tags, thereby to ensure that the target tissue, organ or object has been successfully excised. This step eliminates or at least minimizes the need for radiological re-imaging in the operating room and/or transporting excised tissue from the operating room to an imaging facility for re-imaging and x-ray analysis and/or for

re-excision of tissue.

In its preferred embodiment, the method of the invention further

includes the use during surgery of a grid dip oscillator to pin point, i.e., to identify with precision, the location and orientation of each of the PIT tags or elements implanted in the patient's body. The grid dip oscillator emits a radio frequency signal that energizes each of the PIT tags and causes the same to emit an electromagnetic field which can be scanned by the osciltator to determine with exactitude the precise location and orientation of each tag. This enables the surgeon to determine the most advantageous avenue of approach to and procedure for excision of a target tissue,

organ or object.

In the preferred practice of the method of the invention, one- or more of the PIT locator elements or tags are implanted in the patient's body, usually by a

radiologist, contiguous to a target tissue, organ or object to be excised, for example, to delineate the boundaries of a volume of tissue to be surgically removed from the body. Since the PIT tags are small and embedded in tissue and do not protrude from the body, they are not prone to displacement or dislodgement, and since the tags remain passive until energized from an external radio frequency (RF) source, there is no need to rush or expedite transport of the patient from the radiologist to the surgical suite. It is not necessary to schedule simultaneous or immediately sequential availability of a radiological suite and a surgical suite. A reasonable period of time may elapse between implantation of the PIT tags and performance of the surgery. At the time of surgery, a radio frequency emitting identification (RFID)

scanner is moved or swept over the exterior of the patient's body to energize the tag or tags implanted in the body and to cause the same to emit a signal, readable by the

scanner, indicating the general location of the tag and the identification data pre- recorded on the tag, e.g., the identity of the patient and the surgery to be performed. A radio frequency emitting grid dip oscillator is then employed as a precision instrument to energize the implanted tag or tags, to read the signal or signals emitted by the tag or tags, and to identify with exactitude the location and orientation of each of the tags. As above stated, this enables the surgeon to determine the most surgically and cosmetically advantageous avenue of approach to and procedure for excision of the target tissue, organ or object.

The grid dip oscillator may be deployed externally of the patient's body and/or within the incision during surgery to aid the surgeon in performance of the surgery. The grid dip oscillator is designed to provide a visible signal and/or an audible signal denoting proximity to each PIT element or tag during surgery, thereby to guide the surgeon throughout the course of the surgical procedure, and to insure precise excision of the target tissue, organ or object.

The invention thus assures efficient and reliable location and identification of target tissue, precise and reliable excision of the tissue, significantly less reliance on and/or need for imagining, re-imaging and re-excision, and less time consuming and more efficient and practicable surgical procedures then provided by prior practices. These and other objects and advantages of the invention will become apparent to those of reasonable skill in the art from the following detailed description, as considered in conjunction with the accompanying drawings.

Brief Description of the Drawings

FIG. 1 is a side view of a radio frequency responsive implantable passive integrated transponder element or tag useful in practice of the present

invention;

FlG. 2 is a side view of an illustrative hypodermic syringe that is representative of devices useful as an implantation or deployment device in practice of the invention;

FIG. 3 is a plan view of a radio frequency scanner/reader useful for practice of the invention.

FIG. 4 is a plan view of a radio frequency grid dip oscillator useful for practice of the invention; and

FIG. 5 is an illustration of the mode of use of a grid dip oscillator in practice of the invention.

Detailed Description of a Preferred Embodiment The following is a detailed description of an embodiment of the invention presently deemed by the inventors to be the best mode of carrying out their invention. The invention described herein is appropriate for a range of applications for marking specific volumes of tissue or foreign objects for surgical excision or other purposes. Although the description is largely in the context of marking nonpalpaple lesions in breast tissue for subsequent excision, the invention is not so limited. For

instance, the invention may be used to mark tissue in a variety of locations in the body of a human being or an animal, such as the liver, the lungs, muscle tissue, bones, or other tissue or organs where the advantages of the invention may be realized. It may also be used to mark foreign objects in tissue or body cavities, such as a bullet or the like. Accordingly, the invention as described and claimed below is not limited to the marking and removal of lesions in breast tissue.

FIG. 1 illustrates an implantable, passive integrated transponder (PIT) element or tag 10 useful in practice of the invention. The PIT elementlO comprises a passive integrated transponder 12 attached to a microchip 14 and encapsulated in an implantable glass shell 16. Passive integrated transponders have no battery so the micro chip remains inactive until energized by radio or other low frequency energy from an external source, such as the scanner/reader 30 illustrated in Fig. 3 or the grid dip oscillator 40 illustrated in Fig. 4.

The micro chip 14 in the tag 10 is pre-recorded with a unique code, such as an alphabetic, numeric or alphanumeric code, identifying for example, the identity

of the patient and the surgical procedure to be performed. The scanner 30 sends a low frequency signal to the transponder and micro chip within the tag providing power needed to interrogate the chip and send its unique code back to the scanner thereby to positively identify the tag or element and provide its approximate location in the body. Similarly, the dip grid oscillator 46 sends a low frequency signal to the tag 10 providing power to cause emission from the tag of an electromagnetic field that

is readable by the oscillator to pin-point, i.e., to determine with reasonable precision, the location and the orientation of the tag or element in the body. The distance from which the PIT tag can be read is called the read range.

Many factors contribute to the read range of passive tags including operating frequency, antenna power, tag orientation and interference from other sources. Low frequency tags are detected in milliseconds at close range. PIT elements can be read through materials such as plastic, water and living tissue. In the present invention, it

is significant that the PIT elements can be read from a distance of 0.1 to 20 centimeters, with a preferred range of from immediate proximity up to about 7-10

centimeters. Currently useful range is from proximity up to about 2 centimeters.

The frequency used by the PIT element to transmit its location and information is also significant. The present invention utilizes 134.2 KHz as its most preferred transponder frequency so as not to be absorbed by or interfered with by living tissue, body fluids, or water. The range of useful frequencies can be from 1 Hertz to 5 Giga Hertz with 13 Kilo Hertz (kHz) to 150 kHz being preferred.

Implantation or deployment in a body of one or more of the implantable PIT tags 10 is suitably accomplished by use of any of a number of tag deployment needles or devices, for example, a hypodermic syringe, such as the syringe 20 illustratively depicted in Fig. 2. The syringe 20, as is conventional, includes a body 22, a hollow needle 24 for penetrating tissue and a plunger 26 for ejecting a contained substance or object (a PIT tag) through the needle 24 into the body tissue or cavity. A radiologist, using one or ore of the above-referenced imaging techniques, usually determines the region or location of interest, that is, the^* tissue, volume of tissue, growth, tumor, gland or object to be surgically removed from the

body. This location is herein referred to as the "target", or more fully, the "target

tissue, organ or object." Once the radiologist determines the location of the target in a patient, one or more PIT elements or tags 10 can be implanted in the body at, adjacent, or in proximity to the target by injection via the syringe 20 or other implanter or deployment needle or device. In practice of the invention, the PIT element has a size range of 1 millimeter in diameter to 5 millimeters in diameter, with 2-3 millimeters being preferred, and a length of 2-30 millimeters, with 8-12 millimeters being preferred. In the present invention, a syringe, for example, can be loaded with a PIT

element from the point side and into a needle that ranges in sizetfrom 1- to 10 centimeters long, with 3-5 centimeters long being preferred, with a needle diameter of from 6 to 20 gauge in opening diameter, with 8 to 12 gauge being preferred. In practice of the invention, each PIT element is pre-loaded into an implanter, gas sterilized, and individually packaged for subsequent use.

A reader or scanner 30 capable of locating and detecting PIT elements or tags 10 implanted in a body is depicted illustratively in Fig. 3. The system employed in practice of the invention is preferably a radio frequency identification system. Radio frequency identification (RFID) uses a signal transmitted between an electronic device such as a PIT element and a reading device such as a scanner or reader or transceiver. RFID technology identifies objects remotely through the use of radio frequencies. In the present invention, RFID is used to locate and identify a PIT element that has been implanted into a patient who will undergo surgery to remove the target tissue, organ or object. The scanner can, with relative ease, detect PIT elements embedded up to 7-10 centimeters deep in a body and give the approximate location

and identity of each PIT element to the surgeon without the aid of radiological techniques (which cannot be used during real time surgery).

The scanner/reader 30 illustrated is hand held and battery operated, and contains a radio frequency transmitter and receiver (transceiver), an on/off control button 32 and an LCD read-out screen 34 for displaying the unique code pre-recorded in the microchip of each PIT tag. A RFID scanner/reader suitable for practice of the invention is available from Destron-Fearing Corporation. PIT elements, sterile tag implanter packages, and scanners can be obtained from the Biomark Corporation of Boise, Idaho. These systems have been used to tag, track and identify animals by injecting subcutaneous PTT elements under the animal's skin. However they have not been used in the healthcare field for passively locating suspect tissue and/or foreign objects in a body and for aiding in the performance of surgical procedures to remove malignancies, diseased organs and the like.

In practice of the present invention, radiological techniques, such as X- ray, ultra sound and/or magnetic resonance imaging, may be employed to locate targets, that is, suspect tissue, diseased organs, tumors, foreign objects, etc., in a body. A radiologist, using one or more PIT tags and tag implanters, then marks the location by deploying and implanting one or more tags in the body adjacent or contiguous to the suspect tissue or organ. Two or more tags may, for example, be implanted to bracket, or to outline or delineate the boundaries of, a malignancy, tumor or the like. Once implanted, the tag or tags will maintain their position in the body and will not migrate or be displaced from the location of deployment even though surgery may be delayed for hours or even days. Since the PIT tags are sterile and remain passive until

energized, such delays between implantation and surgery pose no health risks and are of no practical concern. In fact, such permissible delay may prove beneficial in terms of the optimal time for surgery and the patient's overall welfare.

When the patient is taken to the operating room and prepared for surgery, the scanner control button 32 is depressed and the scanner 30 is passed over the patient's body. A radio frequency signal generated by the scanner activates each PIT element when the scanner is within 7-10 centimeters of the element, and a unique alpha numeric character string is then displayed on the LCD screen 34 that identifies the PIT tag.

The display on the screen also serves to notify the surgeon of the location in the patient's body of the detected PIT element, i.e., proximate the position of the scanner. The display may also be accompanied by an audible tone denoting the location of the detected element or tag. A surgeon can, if he or she wishes to do so, then use the scanner or RFID energized elements as markers for excising a target tissue, organ or object. For many surgeries, this is an advantageous practice and constitutes one aspect of the invention.

However, for complex and/or delicate surgeries, more precise location of the PIT elements or tags may be desired. In such cases, the grid dip oscillator 40 illustrated in Figs. 4 and 5 is brought into use. A grid dip meter is an oscillator whose output energy changes in the

vicinity of a circuit which is in resonance with the frequency the oscillator generates, somewhat similar to an acoustic tone becoming louder when generated in the vicinity

of a resonant cavity. For practice of the present invention, a grid dip meter is suitably embodied in a hand held battery operated oscillator or transceiver 40 for transmitting a signal to and receiving a responsive signal from the PIT element or elements implanted in a patient's body. The transmitted signal energizes the transponder in the PIT element and causes it to emit an electromagnetic field, as depicted illustratively at 50 in Fig. 5. The oscillator 40 measures the amount of electromagnetic energy in the field and includes, in a preferred embodiment, a visible graduated display or reading device 42 for visually displaying the sensed value of the electromagnetic field and a

tone generator with speaker 44 for emitting a tone signal as- -a function of the sensed magnitude of the electromagnetic field of the PIT element. The sound projected by the speaker may change in volume or pitch corresponding to the magnitude of the PIT signal.

A grid dip oscillator, preferred for use as a PIT locating device or detection apparatus in practice of the invention, is available from Antenna & Microwave Technologies, Salisbury, South Australia 5108, Australia.

In use, the user, e.g., the surgeon or a surgical assistant, passes or sweeps the oscillator over the patient's body and when the oscillator is brought into proximity to a PIT element, a visible indication will appear on the reader 42 and/or a sound will be emitted by the speaker 44. Then, by moving the oscillator back and forth and/or circularly over the region of the body from which he signal was emitted, the visual display on the reader will move up and down and/or the audible sound will increase and decrease in volume or pitch until a position is reached where the reading

is greatest and/or the sound loudest. This then accurately identifies the location of the PIT element in the body. Further, since the strength of the magnetic field will be greatest at the magnetic poles of the field, i.e., the two ends of the PIT element, the detection and locating apparatus or oscillator 40 also enables the user/surgeon to determine the orientation of each PIT element in the patient's body.

The locator apparatus or oscillator 40 is useful not only in pre-incision analysis of the patient to be operated upon, but is most useful during performance of the surgery itself. Specifically, the unit 40 may be used externally of the body to guide the surgery and may also be sterilized and/or surgically draped for insertion directly into an incision for purposes of providing guidance to the- surgeon for precise excision of a target tissue, volume of tissue, organ or object.

In the course of the surgery, the excision preferably follows the distal side of the tag (the side of the tag opposite the side that is proximate the tissue) so that the tag or tags constitute part of the excised matter.

Then, when the surgery has been completed, but before closing the surgical field or incision, the scanner 30 and/or the oscillator 40 can be energized and passed over the excised matter for the presence of PIT signals, thereby to determine whether the tag or tags have been excised with the matter, and/or the scanner or the oscillator can be passed over the area where surgery was performed for the absence of PIT signals, thereby to determine whether all of the marked tissue was in fact excised. This feature of the invention may, if desired, be used in conjunction with other locating systems, such as hookwires, to insure thorough excision of target tissue. Thus, the success of the surgical procedure can be determined before closing and without need for

radiological re-examination and/or surgical re-excision. Specifically, this invention

enables real time assessment of the PIT (marker) position within a patient and within a specimen, without the need for imaging in the OR, or transport of a specimen outside of the OR to radiographically confirm that the marker is in the resected lesion.

The objects and advantages of the invention have thus been shown to be attained in a convenient, practical, economical and facile manner.

While preferred embodiments of the invention have been herein illustrated and described, it is to be appreciated that various changes, rearrangements and modification may be made therein, and that equivalents thereto may be practiced,

without departing from the scope of the invention as defined by the appended-claims.

Claims

What is Claimed is:

1. A method of locating within a body target tissue, organs and object intended for surgery comprising the steps of providing at least one implantable transponder, providing a transponder implantation device, providing a transponder locating device, prior to surgery, implanting a transponder within the body proximate the target tissue, organ or object, and at the time of surgery, scanning the body for the transponder with the transponder locating device.

2. A method as set for in claim 1 including the step of implanting a plurality of implantable transponders proximate the target tissue, organ or object prior to surgery and, at the time of surgery, scanning the body for the transponders with the transponder locating device.

3. A method as set forth in claim 1 including the step of scanning the body with the transponder locating device following surgery.

4. A method as set forth in claim 1 including the step of scanning surgically excised matter with the transponder locating device following surgery.

5. A method as set forth in claim 1 wherein the transponder locating device comprises a radio frequency transmitting and receiving device.

6. A method as set forth in claim 1 wherein the transponder locating device comprises a radio frequency identification scanner.

7. A method as set forth in claim 1 wherein the transponder locating device comprises a grid dip meter.

8. A method of locating and identifying within a body target tissue, organs and objects intended for surgery comprising the steps of

providing at least one implantable transponder containing an identifier, providing a transponder identification reading device, prior to surgery, implanting a transponder within the body proximate the target tissue, organ or object, and at the time of surgery, locating and identifying the transponder by scanning the body for the transponder with the transponder identification reading device.

9. A method as set forth in claim 8 including the steps of providing a dip grid meter and, after locating and identifying the transponder, scanning the body with the grid dip meter to pin point the location of the transponder.

10. A method as set forth in claim 9 including the step of employing the grid dip meter during surgery to continue pin-pointing the location of the transponder during performance of the surgery.

11. A method as set forth in claim S including the steps of providing

a plurality of implantable transponders each containing an identifier, implanting the plurality of implantable transponders within the body proximate the target tissue, organ or object prior to surgery, at the time of surgery, locating and identifying the transponders by scanning the body for the transponders with the transponder identification reading device,

providing a grid dip meter and, after locating the transponders, scanning the bqdy with the grid dip meter to pin point the location of each of the transponders, and during surgery, employing the grid dip meter to continue pin-pointing the locations of the transponders during performance of the surgery.

12. A method as set forth in claim 11 including the steps, following surgery, of scanning the body and/or surgically excised matter with the transponder identification device and/or the grid dip meter.

13. A method as set forth in claim 9 wherein the transponder comprises a radio frequency responsive passive integrated transponder and the transponder identification reading device and grid dip meter each comprises a radio

frequency transmitter and receiver.

14. A procedure for use in surgically removing target tissue, organs

and objects from a body comprising the steps of prior to surgery, implanting at least one implantable transponder within the body proximate the target tissue, organ or object, at the time of surgery, locating the target tissue, organ or object, by scanning the body with transponder locating means, and following surgery, scanning one or the other or both of the body and surgically excised matter with the transponder locating means.

15. A method as set forth in claim 14 wherein the transponder comprises a radio frequency responsive passive integrated transponder and the locating means comprises one or the other or both of a radio frequency identification scanner and a radio frequency grid dip meter.

16. A procedure as set forth in claim 15 including the step of energizing the at least one transponder at a radio frequency within the range of from about 13 kilo hertz to about 150 kilo hertz.

17. A procedure as set forth in claim 15 including the step of energizing the at least one transponder for reading by said locating means at a range of

up to about 10 centimeters.

18. A method for use in surgically removing target tissue, organs and objects from a body comprising the steps of prior to surgery, implanting at least one implantable transponder containing an identifier within the body proximate the target tissue, organ or object, at the time of surgery, locating and identifying the target tissue, organ or object by scanning the body with transponder locating and identifier reading means, and during surgery, pin-pointing the target tissue, organ or object by employing a grid dip meter to pin-point the location of the transponder.

19. A method as set forth in claim 18 including the steps of implanting a plurality of transponders proximate the boundaries of the target tissue, organ or object, employing the grid dip meter during surgery to pin-point the locations of the transponders during performance of the surgery, excising tissue from the body along the margins of the transponders distal to the target tissue, organ or object, and scanning the surgically excised matter for presence of the transponders and/or scanning the body for absence of the transponders.

20. A method as set forth in claim 19 wherein the steps recited in claim 19 are completed in the operating room prior to closing the surgical field.