FIELD OF THE INVENTION

The present invention relates to implantable markers or tags, and to systems and methods for localizing such markers within a patient's body, e.g., during surgical procedures or other procedures, such as during lumpectomy procedures.

BACKGROUND

Before a biopsy or surgical procedure to remove a lesion within a breast, e.g., during a lumpectomy procedure, the location of the lesion must be identified. For example, mammography or ultrasound imaging may be used to identify and/or confirm the location of the lesion before the procedure. The resulting images may be used by a surgeon during the procedure to identify the location of the lesion and guide the surgeon, e.g., during dissection to access and/or remove the lesion. However, such images are generally two dimensional and therefore provide only limited guidance for localization of the lesion since the breast and any lesion to be removed are three-dimensional structures. Further, such images may provide only limited guidance in determining a proper margin around the lesion, i.e., defining a desired specimen volume to be removed.

To facilitate localization, immediately before a procedure, a wire may be inserted into the breast, e.g., via a needle, such that a tip of the wire is positioned at the location of the lesion. Once the wire is positioned, it may be secured in place, e.g., using a bandage or tape applied to the patient's skin where the wire emerges from the breast. With the wire placed and secured in position, the patient may proceed to surgery, e.g., to have a biopsy or lumpectomy performed.

One problem with using a wire for localization is that the wire may move between the time of placement and the surgical procedure. For example, if the wire is not secured sufficiently, the wire may move relative to the tract used to access the lesion and consequently the tip may misrepresent the location of the lesion. If this occurs, when the location is accessed and tissue removed, the lesion may not be fully removed and/or healthy tissue may be unnecessarily removed. In addition, during the procedure, the surgeon may merely estimate the location of the wire tip and lesion, e.g., based on mammograms or other images obtained during wire placement, and may proceed with dissection without any further guidance. Again, since such images are two dimensional, they may provide limited guidance to localize the lesion being treated or removed.

Alternatively, it has been suggested to place a radioactive seed to provide localization during a procedure. For example, a needle may be introduced through a breast into a lesion, and then a seed may be deployed from the needle. The needle may be withdrawn, and the position of the seed may be confirmed using mammography. During a subsequent surgical procedure, a hand-held gamma probe may be placed over the breast to identify a location overlying the seed. An incision may be made and the probe may be used to guide excision of the seed and lesion.

Accordingly, apparatus and methods for localization of lesions or other tissue structures in advance of and/or during surgical, diagnostic, or other medical procedures would be useful.

SUMMARY

The present invention is directed to implantable markers and tags, and to systems and methods for localizing such markers within a patient's body, e.g., during surgical procedures or other procedures, such as during lumpectomy procedures.

In accordance with one embodiment, a marker is provided sized for introduction into a target tissue region within a patient's body that includes an energy converter for transforming light energy striking the marker into electrical energy; a switch; an antenna coupled to the switch; and a storage circuit coupled to the energy converter for storing electrical energy generated by the energy converter until a predetermined threshold is achieved, the storage circuit coupled to the switch for closing the switch when the predetermined threshold is achieved to deliver electrical energy to the antenna, whereupon the antenna transmits a radio frequency (RF) signal.

In accordance with another embodiment, a marker is provided sized for introduction into a target tissue region within a patient's body that includes one or more photosensitive diodes to convert light received from a light source outside a patient's body into electrical energy; an antenna; and a circuit comprising a capacitor coupled to the one or more photosensitive diodes for storing the electrical energy, a threshold element coupled to the capacitor and a switch, the threshold element configured to close the switch when the electrical energy stored by the capacitor reaches a threshold voltage to deliver electrical energy to the antenna, whereupon the antenna transmits a radio frequency (RF) pulse.

In accordance with still another embodiment, a system is provided for localizing a marker within a body that includes a marker sized for introduction into a target tissue region within a patient's body comprising an energy converter for transforming light energy striking the marker into electrical energy, a switch, an antenna coupled to the switch, and a storage circuit coupled to the energy converter for storing electrical energy generated by the energy converter until a predetermined threshold is achieved, the storage circuit coupled to the switch for closing the switch when the predetermined threshold is achieved to deliver electrical energy to the antenna, whereupon the antenna transmits a radio frequency (RF) signal; a probe comprising a light source configured to transmit a transmit light into the patient's body towards the marker; a receive antenna configured to receive the RF signal transmitted by the marker; a processor coupled to the receive antenna for correlating a frequency of the RF signals from the marker to a distance from the probe to the target tissue region within which the marker is introduced; and an output device coupled to the processor for providing information related to the distance.

In accordance with yet another embodiment, a method is provided for localization of a target tissue region within a patient's body that includes implanting a marker within a patient's body, the marker comprising an energy converter, an antenna, and a circuit coupled to the energy converter and the antenna; placing a probe adjacent the patient's body oriented towards the marker; activating the probe to deliver light energy into the patient's body such that the energy converter transforms the light energy into electrical energy that is periodically delivered to the RF antenna via the circuit such that the RF antenna transmits RF pulses; and correlating a frequency of the RF pulses to a distance from the probe to the marker.

Other aspects and features of the present invention will become apparent from consideration of the following description taken in conjunction with the accompanying drawings.

