Electromagnetic Navigational Bronchoscopy-guided Fiducial Markers for Lung Stereotactic Body Radiation Therapy: Analysis of Safety, Feasibility, and Interfraction Stability

Nabavizadeh, Nima MD*; Zhang, Junan PhD*; Elliott, David A. MD*; Tanyi, James A. PhD*; Thomas, Charles R. Jr MD*; Fuss, Martin MD*; Deffebach, Mark MD†,‡

Journal of Bronchology & Interventional Pulmonology: April 2014 - Volume 21 - Issue 2 - p 123–130
doi: 10.1097/LBR.0000000000000065
Original Investigations

Background: Embolization coils as fiducial markers for pulmonary stereotactic body radiation therapy (SBRT) are perceived to be the optimal marker type, given their ability to conform and anchor within the small airways. The aim of our study was to assess retention, placement, migration, feasibility, and safety of electromagnetic navigational bronchoscopy (ENB)-guided embolization coil markers throughout courses of SBRT.

Methods: Thirty-one patients with 34 nodules underwent ENB-guided fiducial placement of several 4 mm fibered platinum embolization coils before SBRT. Patient and nodule positioning was confirmed with daily pretreatment cone-beam computed tomography (CBCT). Fiducial positional characteristics were analyzed utilizing radiation treatment-planning software comparing the simulation CT with daily CBCTs.

Results: Of 105 fiducials placed, 103 were identifiable on simulation CT (retention rate: 98.1%). Incidence of asymptomatic pneumothoraces was 6%. One patient experienced hemoptysis requiring hospitalization. Eighty-six percent of fiducials were placed within 1 cm of the nodule, with 52% of fiducials placed directly on the nodule surface. Throughout a 5-fraction SBRT course, fiducial displacement was <7, 5, and 2 mm in 98%, 96%, and 67% of pretreatment CBCTs.

Conclusions: ENB placement of embolization coils as fiducials for lung SBRT image guidance is associated with a low rate of iatrogenic pneumothoraces, and resulted in reliable placement of the fiducials in close proximity to the lung nodule. Embolization coils retained their relative position to the nodule throughout the course of SBRT, and provide an excellent alternative to linear gold seeds.

*Department of Radiation Medicine

Division of Pulmonary and Critical Care Medicine, Oregon Health and Science University

Pulmonary and Critical Care Medicine, Department of Veterans Affairs Medical Center, Portland, OR

Disclosure: M.F. serves as a consultant for Varian Medical Systems and VisionRT Medical; he has also received payment for lectures from Varian Medical Systems. For the remaining authors, there are no conflict of interest or other disclosures.

Reprints: Nima Nabavizadeh, MD, Department of Radiation Medicine, Oregon Health and Science University, 3181 SW Sam Jackson Park Rd. KPV4, Portland, OR 97239 (e-mail: nabaviza@ohsu.edu).

Received December 9, 2013

Accepted February 24, 2014

© 2014 by Lippincott Williams & Wilkins.