A simple endoscopic method with radial endobronchial ultrasonography for low-migration rate coil-tailed fiducial marker placement

BACKGROUND: Fiducial markers (FMs) are useful for tracking small peripheral lung nodules (PLN) before stereotactic radiotherapy, but migration over the course of treatment may result in inaccurate dosing to the tumor. To minimize FM migration, coil-tailed FMs have been designed. Our objective was to assess both the feasibility of radial endobronchial ultrasonography (r-EBUS) placement and the migration rate of coil-tailed FMs. METHODS: In this retrospective study, we included patients who received r-EBUS guided placement of coil-tailed FMs for PLN <25 mm from June 2015 to May 2018. We introduced the FM into the nodule with the use of bronchial brush, without fluoroscopy. RESULTS: Thirty patients had r-EBUS guided placement of a coil-tailed FM before stereotactic radiation therapy. Nodule’s median long- and short-axis diameters were 15 mm (8–25 mm) and 8 mm (5–20 mm), respectively; short diameter of 27 nodules (90%) was less than 15 mm. All nodules were reached and visualized with r-EBUS, with an ultrasound (US) signal showing a centered or tangential probe in 26 and 4 cases, respectively. No immediate complication was reported. Twenty-three patients had stereotactic radiation therapy within a median time of 29 days (14–126 days). No FM migration occurred between r-EBUS placement and radiotherapy. Pre-treatment planning and 3-month follow-up CT scans showed that all FMs stayed in direct contact with the lesions. CONCLUSIONS: r-EBUS is a safe procedure for the placement of nitinol coil FMs, which have a low migration rate.