Int J CARS (2007) 2:1–10 DOI 10.1007/s11548-007-0078-4 ORIGINAL ARTICLE A real-time navigation system for laparoscopic surgery based on three-dimensional ultrasound using magneto-optic hybrid tracking configuration Kozo Konishi · Masahiko Nakamoto · Yoshihiro Kakeji · Kazuo Tanoue · Hirofumi Kawanaka · Shohei Yamaguchi · Satoshi Ieiri · Yoshinobu Sato · Yoshihiko Maehara · Shinichi Tamura · Makoto Hashizume Received: 13 November 2006 / Accepted: 6 March 2007 / Published online: 25 April 2007 © CARS 2007 Abstract Objectives In laparoscopic liver surgery, intraoperative navigation is strongly recommended. We developed a nav- igation system based on intraoperative ultrasound (IOUS). The purpose of this study was to evaluate the usefulness and accuracy of this system using an animate model. Materials and methods Augmented reality (AR) visualiza- tion superimposing three-dimensional ultrasound (3D-US) images onto captured laparoscopic live images was constructed. We employed magneto-optic hybrid tracking configuration and a rapid method of magnetic distortion K. Konishi Department of Innovative Medical Technology, Kyushu University, Fukuoka, Japan K. Konishi · Y. Kakeji · H. Kawanaka · S. Yamaguchi · Y. Maehara Department of Surgery and Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan S. Yamaguchi · S. Ieiri · M. Hashizume Department of Disaster and Emergency Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan K. Tanoue · M. Hashizume Center for Integration of Advanced Medicine, Life Science and Innovative Technology, Kyushu University, Fukuoka, Japan M. Nakamoto · Y. Sato · S. Tamura Division of Interdisciplinary Image Analysis, Osaka University Graduate School of Medicine, Osaka, Japan M. Hashizume (B ) 3-1-1 Maidashi Higashi-ku, Fukuoka 812-8582, Japan e-mail: mhashi@dem.med.kyushu-u.ac.jp correction. Twelve pigs and liver tumor mimics were used, and effects of magnetic distortion correction and accuracy of 3D-US navigation were evaluated. Results Using magnetic distortion correction, tracking error was significantly reduced. Each ultrasound scanning time was within 30 s, and the time to generate 3D-US images was within 3 min. All tumor mimics were successfully puncture- guided with navigation. Registration accuracy was signifi- cantly improved from 17.2 ± 5.27 to 1.96 ± 0.87 mm. Conclusion We developed an AR navigation system based on IOUS. Experimental results showed that the proposed method was effective, and could be used in clinical settings. 3D-US, as an imaging modality allows real-time imaging regardless of organ shifts or distortion. Keywords Augmented reality (AR) · Navigation · 3D-US · Laparoscopic surgery · Image-guided surgery (IGS) Abbreviations IOUS intraoperative ultrasound AR augmented reality 3D-US three-dimensional ultrasound DOF degrees of freedom ROI region of interest CT computed tomography RMS root mean square IGS image-guided surgery Introduction The laparoscopic treatment of primary and metastatic liver tumors is feasible in appropriate settings [1–4]. However, indications of laparoscopic treatment are still limited despite 123