Radiofrequency identification tags for preoperative tumor localization: proof of concept.

OBJECTIVE: The objective of our study was to experimentally explore the potential for tumor localization using radiofrequency identification (RFID) tags and a newly developed handheld RFID detector. MATERIALS AND METHODS: A unique RFID detector that combines the use of multiple interchangeable detector probes with both audio and LCD display signals was invented, allowing precise localization and identification of RFID tags. Accurate localization and identification were validated using this handheld RFID detector (TagFinder) and RFID tags of 2-mm diameter and 8- or 12-mm lengths. Experiments included the following: validation in various breast phantoms; differentiation of 4- to 6-cm-diameter tissue specimens with and without tags; determination of the nearest differentiable distance between two tags; proof of visualization of tags on sonography, radiography, and MRI; and experimental localization and resection of RFID-labeled tissue specimens. RESULTS: Both 8- and 12-mm-length RFID tags implanted < 6 cm deep were accurately localized and uniquely identified. Chicken breast specimens of 4- to 6-cm diameter implanted with RFID tags were accurately differentiated from specimens without tags. Tags in proximity could be reliably differentiated and uniquely identified when placed as close as 0-2 cm apart, depending on the tags' precise orientations. RFID tags were easily visualized with sonography, mammography, and MRI, with artifacts present only on MRI. Localization and resection of RFID tags in the labeled tissue region were successful in grocery store-bought chicken breasts. CONCLUSION: The combination of RFID tags and a new handheld RFID detector shows promise for preoperative imaging-guided tumor localization.