Multimodality guidance for accurate bronchoscopic insertion of fiducial markers

Abstract

Introduction: Fiducial markers act as visible surrogates of tumor position during image-guided radiotherapy. Marker placement has been attempted percutaneously but is associated with high rates of pneumothorax and chest drain placement. Methods: Patients undergoing radical radiation treatment for non-small-cell lung cancer underwent bronchoscopic implantation of gold fducials using radial probe endobronchial ultrasound (EBUS) with virtual bronchoscopy and fuoroscopic guidance to achieve tumor localization and placement within/adjacent to peripheral lung tumors. For tumors not localized using radial EBUS, fducial placement was achieved by electromagnetic navigation to the vicinity of the tumor. Results: Eighteen fducials were placed to mark 16 lesions in 15 patients. In nine patients (60%), fducials were implanted at the time of diagnostic bronchoscopy. No procedural complications occurred. EBUS localization allowed marker implantation within the target lesion in 12 cases. In four lesions, electromagnetic navigation bronchoscopy-guided implantation achieved a median fducial-lesion distance of 6 mm (mean 12 mm). No marker migration occurred after the implantation of two-band markers; however, early migration was observed in two of eight (25%) of the smaller linear fducials. No migration during the course of radiation therapy was observed. Conclusion: Fiducial marker placement is easily and safely performed bronchoscopically, including at the time of diagnostic bronchoscopy. Marker geometry appears important in stability of bronchoscopically inserted fducials. Future studies are required to confrm the optimal marker size, geometry, and spatial relationship with the target lesion.