First clinical use of the EchoTrack guidance approach for radiofrequency ablation of thyroid gland nodules.
OBJECTIVE
Percutaneous radiofrequency ablation (RFA) of thyroid nodules is an alternative to surgical resection that offers the benefits of minimal scars for the patient, lower complication rates, and shorter treatment times. Ultrasound (US) is the preferred modality for guiding these procedures. The needle is usually kept within the US scanning plane to ensure needle visibility. However, this restricts flexibility in both transducer and needle movement and renders the procedure difficult, especially for inexperienced users. Existing navigation solutions often involve electromagnetic (EM) tracking, which requires placement of an external field generator (FG) in close proximity of the intervention site in order to avoid distortion of the EM field. This complicates the clinical workflow as placing the FG while ensuring that it neither restricts the physician's workspace nor affects tracking accuracy is awkward and time-consuming.


METHODS
The EchoTrack concept overcomes these issues by combining the US probe and the EM FG in one modality, simultaneously providing both real-time US and tracking data without requiring the placement of an external FG for tracking. We propose a system and workflow to use EchoTrack for RFA of thyroid nodules.


RESULTS
According to our results, the overall error of the EchoTrack system resulting from errors related to tracking and calibration is below 2 mm. Navigated thyroid RFA with the proposed concept is clinically feasible. Motion of internal critical structures relative to external markers can be up to several millimeters in extreme cases.


CONCLUSIONS
The EchoTrack concept with its simple setup, flexibility, improved needle visualization, and additional guidance information has high potential to be clinically used for thyroid RFA.
Division of Computer Assisted Medical Interventions, German Cancer Research Center (DKFZ), Heidelberg, Germany. a.franz@dkfz.de.
Alfred Michael
AM
Franz
Division of Computer Assisted Medical Interventions, German Cancer Research Center (DKFZ), Heidelberg, Germany.
Alexander
A
Seitel
Division of Computer Assisted Medical Interventions, German Cancer Research Center (DKFZ), Heidelberg, Germany.
Nasrin
N
Bopp
Department of Nuclear Medicine, University Hospital Frankfurt, Frankfurt, Germany.
Christian
C
Erbelding
Division of Computer Assisted Medical Interventions, German Cancer Research Center (DKFZ), Heidelberg, Germany.
Dominique
D
Cheray
Division of Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
Stefan
S
Delorme
Department of Nuclear Medicine, University Hospital Frankfurt, Frankfurt, Germany.
Frank
F
Grünwald
Department of Nuclear Medicine, University Hospital Frankfurt, Frankfurt, Germany.
Hüdayi
H
Korkusuz
Division of Computer Assisted Medical Interventions, German Cancer Research Center (DKFZ), Heidelberg, Germany.
Lena
L
Maier-Hein
D017115:Catheter Ablation / Q000379:methods*; D006801:Humans; D009038:Motion; D025321:Surgery, Computer-Assisted / Q000379:methods*; D013961:Thyroid Gland / Q000601:surgery*; D016606:Thyroid Nodule / Q000601:surgery*; D014463:Ultrasonography / Q000379:methods*
Computer-assisted interventions; Electromagnetic tracking; Thyroid radiofrequency ablation; Ultrasound guidance