title: Progressive internal landmark registration for surgical navigation in laparoscopic gastrectomy for gastric cancer.
abstract: OBJECTIVE
  A surgical navigation system supports the comprehension of anatomical information during surgery. Patient-to-image registration is the alignment process between CT volume and patient coordinate systems. Achieving accurate registration in the surgical navigation of laparoscopic surgery is very challenging due to soft tissue deformation. This paper presents a new patient-to-image registration method based on internal anatomical landmarks for improving registration accuracy in the surgical navigation of laparoscopic gastrectomy for gastric cancer.
  
  
  METHODS
  Our proposed registration method progressively utilizes internal anatomical landmarks. In laparoscopic gastrectomy for gastric cancer, the surgeon cuts the blood vessels around the stomach. The positions of the cut vessels are sequentially used as fiducials for registration during surgery. The proposed method uses a weighted point-based registration method for computing the transformation matrix using the fiducials both on the body surface and on the blood vessels. When a blood vessel is cut during surgery, the proposed progressive registration method measures the cut vessel's position and computes a transformation matrix by adding the cut vessel as a fiducial.
  
  
  RESULTS
  We applied our proposed progressive registration method using the positional information of the blood vessels acquired during laparoscopic gastrectomy in 20 cases. We evaluated it using target registration error in four blood vessels. The average target registration error in the four blood vessels was 12.6 mm and ranged from 2.1 to 32.9 mm.
  
  
  CONCLUSIONS
  Since the proposed progressive registration can reduce registration error, our proposed method is very useful for the surgical navigation of laparoscopic gastrectomy. Our proposed progressive registration method might increase the accuracy of surgical navigation in laparoscopic gastrectomy.
authors.affiliation: Information & Communications, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan. yhayashi@mori.m.is.nagoya-u.ac.jp.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Hayashi
authors.affiliation: Department of Gastroenterological Surgery, Aichi Cancer Center Hospital, 1-1 Kanokoden, Chikusa-ku, Nagoya, 464-8681, Japan.
authors.forename: Kazunari
authors.initials: K
authors.lastname: Misawa
authors.affiliation: Information Technology Center, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan.|Centre for Medical Image Computing, University College London, Gower Street, London, WC1E 6BT, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Hawkes
authors.affiliation: Information & Communications, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan.
authors.forename: Kensaku
authors.initials: K
authors.lastname: Mori
mesh_terms: D000328:Adult; D000368:Aged; D059925:Anatomic Landmarks / Q000000981:diagnostic imaging*; D005260:Female; D005743:Gastrectomy / Q000379:methods*; D006801:Humans; D010535:Laparoscopy / Q000379:methods; D008297:Male; D008875:Middle Aged; D013274:Stomach Neoplasms / Q000000981:diagnostic imaging / Q000601:surgery*; D025321:Surgery, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed
keywords: Gastric cancer; Laparoscopic gastrectomy; Laparoscopic surgery; Registration; Surgical navigation
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