Bronchoscopic implantation of a novel wireless electromagnetic transponder in the canine lung: a feasibility study.
OBJECTIVE
The success of targeted radiation therapy for lung cancer treatment is limited by tumor motion during breathing. A real-time, objective, nonionizing, electromagnetic localization system using implanted electromagnetic transponders has been developed (Beacon electromagnetic transponder, Calypso Medical Technologies, Inc., Seattle, WA). We evaluated the feasibility and fixation of electromagnetic transponders bronchoscopically implanted in small airways of canine lungs and compared to results using gold markers.


METHODS
After approval of the Animal Studies Committee, five mongrel dogs were anesthetized, intubated, and ventilated. Three transponders were inserted into the tip of a plastic catheter, passed through the working channel of a flexible bronchoscope, and implanted into small airways of a single lobe using fluoroscopic guidance. This procedure was repeated for three spherical gold markers in the opposite lung. One, 7, 14, 28, and 60 days postimplantation imaging was used to assess implant fixation.


RESULTS
Successful bronchoscopic implantation was possible for 15 of 15 transponders and 12 of 15 gold markers; 3 markers were deposited in the pleural space. Fixation at 1 day was 15 of 15 for transponders and 12 of 12 for gold markers. Fixation at 60 days was 6 of 15 for transponders and 7 of 12 for gold markers, p value = 0.45.


CONCLUSIONS
Bronchoscopic implantation of both transponders and gold markers into the canine lung is feasible, but fixation rates are low. If fixation rates can be improved, implantable electromagnetic transponders may allow improved radiation therapy for lung cancer by providing real-time continuous target tracking. Developmental work is under way to improve the fixation rates and to reduce sensitivity to implantation technique.
Mayse
Martin L
ML
Division of Pulmonary and Critical Care, Washington University School of Medicine, St. Louis, MO 63110, USA.
Parikh
Parag J
PJ
Lechleiter
Kristen M
KM
Dimmer
Steven
S
Park
Mia
M
Chaudhari
Amir
A
Talcott
Michael
M
Low
Daniel A
DA
Bradley
Jeffrey D
JD
D000818:Animals; D004285:Dogs; D055590:Electromagnetic Phenomena / Q000295:instrumentation*; D005240:Feasibility Studies; D006046:Gold; D008168:Lung; D008175:Lung Neoplasms / Q000532:radiotherapy*; D009068:Movement; D019736:Prostheses and Implants; D019919:Prosthesis Implantation / Q000379:methods; D020266:Radiotherapy, Conformal
D006046:Gold