We developed a novel localization technique for small intrapulmonary lesions using radiofrequency identification (RFID) technology. Micro-RFID markers with nickel-titanium coils were designed to be placed from subsegmental bronchi to the peripheral parenchyma. In this preclinical study, thoracoscopic subsegmentectomy of a canine pseudotumor model was performed to demonstrate the feasibility and three-dimensional positional accuracy of the system. To recover subcentimeter pseudotumors, markers were bronchoscopically placed to determine the resection line: (1) next to the pseudotumor; (2) in the responsible subsegmental bronchi as the central margin; and (3) on the intersubsegmental plane as the lateral margin. Specific marker positions were located by wireless communication using a wand-shaped probe with a 30-mm communication range, with the distance to the marker indicated by gradual changes in sound pitch. Thirty-four markers were placed for 10 pseudotumors (14.6 mm from the pleura) in 10 canines. Three markers were placed at a mean distance of 5.5 mm from the pseudotumors, and 11 central and 20 lateral markers were placed at mean distances of 17.2 and 20.7 mm from the pseudotumors, respectively. Central markers (20.5 mm from the pleura) were detected within 16.0 seconds in 2.9-mm-diameter bronchi. All resection stumps were within 5.4 mm (range 2-8 mm) from each marker, and pseudotumors were removed with adequate surgical margins toward the central (11.5 mm; range 7-16 mm) and lateral (12.4 mm; range 9-17 mm) directions. RFID wireless markers provided precise three-dimensional positional information and are a potential viable alternative to conventional markers.
Keywords: electromagnetic navigation bronchoscopy; localization; navigation surgery; radiofrequency identification; small lung lesions; video-assisted thoracoscopic surgery.
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