title: High retention and safety of percutaneously implanted endovascular embolization coils as fiducial markers for image-guided stereotactic ablative radiotherapy of pulmonary tumors.
abstract: OBJECTIVE
  To compare the retention rates of two types of implanted fiducial markers for stereotactic ablative radiotherapy (SABR) of pulmonary tumors, smooth cylindrical gold "seed" markers ("seeds") and platinum endovascular embolization coils ("coils"), and to compare the complication rates associated with the respective implantation procedures.
  
  
  METHODS
  We retrospectively analyzed the retention of percutaneously implanted markers in 54 consecutive patients between January 2004 and June 2009. A total of 270 markers (129 seeds, 141 coils) were implanted in or around 60 pulmonary tumors over 59 procedures. Markers were implanted using a percutaneous approach under computed tomography (CT) guidance. Postimplantation and follow-up imaging studies were analyzed to score marker retention relative to the number of markers implanted. Markers remaining near the tumor were scored as retained. Markers in a distant location (e.g., pleural space) were scored as lost. CT imaging artifacts near markers were quantified on radiation therapy planning scans.
  
  
  RESULTS
  Immediately after implantation, 140 of 141 coils (99.3%) were retained, compared to 110 of 129 seeds (85.3%); the difference was highly significant (p<0.0001). Of the total number of lost markers, 45% were reported lost during implantation, but 55% were lost immediately afterwards. No additional markers were lost on longer-term follow-up. Implanted lesions were peripherally located for both seeds (mean distance, 0.33 cm from pleural surface) and coils (0.34 cm) (p=0.96). Incidences of all pneumothorax (including asymptomatic) and pneumothorax requiring chest tube placement were lower in implantation of coils (23% and 3%, respectively) vs. seeds (54% and 29%, respectively; p=0.02 and 0.01). The degree of CT artifact was similar between marker types.
  
  
  CONCLUSIONS
  Retention of CT-guided percutaneously implanted coils is significantly better than that of seed markers. Furthermore, implanting coils is at least as safe as implanting seeds. Using coils should permit implantation of fewer markers and require fewer repeat implantation procedures owing to lost markers.
authors.affiliation: Department of Radiation Oncology, Stanford University, Stanford, California 94305-5847, USA.
authors.forename: Julian C
authors.initials: JC
authors.lastname: Hong
authors.forename: Yao
authors.initials: Y
authors.lastname: Yu
authors.forename: Aarti K
authors.initials: AK
authors.lastname: Rao
authors.forename: Sonja
authors.initials: S
authors.lastname: Dieterich
authors.forename: Peter G
authors.initials: PG
authors.lastname: Maxim
authors.forename: Quynh-Thu
authors.initials: QT
authors.lastname: Le
authors.forename: Maximilian
authors.initials: M
authors.lastname: Diehn
authors.forename: Daniel Y
authors.initials: DY
authors.lastname: Sze
authors.forename: Nishita
authors.initials: N
authors.lastname: Kothary
authors.forename: Billy W
authors.initials: BW
authors.lastname: Loo
mesh_terms: D000368:Aged; D016477:Artifacts; D015505:Chest Tubes; D004621:Embolization, Therapeutic / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D005260:Female; D057918:Fiducial Markers / Q000009:adverse effects; D005548:Foreign-Body Migration / Q000000981:diagnostic imaging; D006046:Gold; D006801:Humans; D008175:Lung Neoplasms / Q000601:surgery*; D008297:Male; D010984:Platinum; D011030:Pneumothorax / Q000209:etiology / Q000628:therapy; D015641:Radiography, Interventional / Q000379:methods; D016634:Radiosurgery / Q000295:instrumentation / Q000379:methods*; D012189:Retrospective Studies; D015607:Stents / Q000009:adverse effects; D014057:Tomography, X-Ray Computed
chemical_list: D010984:Platinum; D006046:Gold