Real-time tracking of liver motion and deformation using a flexible needle

Abstract

Purpose A real-time 3D image guidance system is needed to facilitate treatment of liver masses using radiofrequency ablation, for example. This study investigates the feasibility and accuracy of using an electromagnetically tracked flexible needle inserted into the liver to track liver motion and deformation. Methods This proof-of-principle study was conducted both ex vivo and in vivo with a CT scanner taking the place of an electromagnetic tracking system as the spatial tracker. Deformations of excised livers were artificially created by altering the shape of the stage on which the excised livers rested. Free breathing or controlled ventilation created deformations of live swine livers. The positions of the needle and test targets were determined through CT scans. The shape of the needle was reconstructed using data simulating multiple embedded electromagnetic sensors. Displacement of liver tissues in the vicinity of the needle was derived from the change in the reconstructed shape of the needle. Results The needle shape was successfully reconstructed with tracking information of two on-needle points. Within 30 mm of the needle, the registration error of implanted test targets was 2.4 ± 1.0 mm ex vivo and 2.8 ± 1.5 mm in vivo. Conclusion A practical approach was developed to measure the motion and deformation of the liver in real time within a region of interest. The approach relies on redesigning the often-used seeker needle to include embedded electromagnetic tracking sensors. With the nonrigid motion and deformation information of the tracked needle, a single- or multimodality 3D image of the intraprocedural liver, now clinically obtained with some delay, can be updated continuously to monitor intraprocedural changes in hepatic anatomy. This capability may be useful in radiofrequency ablation and other percutaneous ablative procedures.

Electromagnetic tracking (EMT) technology for improved treatment quality assurance in interstitial brachytherapy

“…Examples are tracking of instruments in surgical interventions,14 guidance of biopsies,15 and motion monitoring in ablation 16 or external beam radiation therapy 17. A review of the technological fundamentals and the clinical applications is given by Franz et al 18.…”

Real-time catheter tracking for high-dose-rate prostate brachytherapy using an electromagnetic 3D-guidance device: A preliminary performance study

“…By adjusting sampling rates to times when eddy currents are decaying or died out, dc trackers can theoretically operate with minimal or no distortion. The EMT has been widely used for position sensing in virtual reality, 7 interventional radiology, 8 ultrasound guided biopsy, intraoperative guidance, [9][10][11] physical therapy, 12,13 body and organ motion monitoring, 14,15 and radiation therapy. 16 The performance of dc tracking provided by Ascension Technology has been previously discussed.…”

A Current Update on the Rule of Alternative and Complementary Medicine in the Treatment of Liver Diseases

“…The motion and deformation of the liver in real time within a region of interest can be measured by a real-time 3D image guidance system with a seeker needle including embedded electromagnetic tracking sensors [10]. This facility is useful in radiofrequency ablation and other percutaneous ablative procedures for treatment of space-occupying lesions.…”

“…These factors imply that the treatment of liver diseases is complicated and full of difficulties. Management of liver diseases should not be simplified, and one should concern all the aspects of the diseased parts, with the overall situation of the liver being considered [10, 11]. A comprehensive but pinpoint therapy is ideal.…”