title: The intersegmental plane of the liver is not always flat--tricks for anatomical liver resection.
abstract: OBJECTIVE
  To investigate the actual three-dimensional (3D) anatomy of the intersegmental plane of the liver to enable safe and precise anatomic resections of the portal territories.
  
  
  BACKGROUND
  Anatomic resection of the liver requires the precise detection of the intersegmental plane. However, we have sometimes encountered a dissociation between conventional understanding of the anatomy of the intersegmental plane and its actual 3D shape.
  
  
  METHODS
  3D simulations of the livers of 81 healthy donors for living donor liver transplantation were reviewed. Several key angles formed between the plane of each venous trunk and the actual intersegmental plane on 3D simulation images were measured. The relation between these angles and the volume ratio of the liver segments located on both sides of the intersegmental plane were also investigated.
  
  
  RESULTS
  The dissociation between the plane of the venous trunks and the actual intersegmental plane was remarkable, especially in the subphrenic region of the right lobe. The volume ratio of segment VIII compared with segment VII was correlated with the degree of cranio-lateral protrusion of segment VIII (r=0.35, P=0.001); this finding was attributed to the intricate surface of the right portal scissura. The same tendency was observed in the left portal scissura between the angle and the volume ratio of segment III/II (r=0.23, P=0.049), whereas the main portal scissura exhibited a relatively flat surface compared with the other longitudinal scissurae.
  
  
  CONCLUSIONS
  The intersegmental plane of the liver has an uneven and curved surface, especially in the right and left portal scissurae. The identification and exposure of the landmark vein on the cut surface is an important technique for avoiding disorientation during anatomic liver resection.
authors.affiliation: Hepato-biliary-pancreatic Surgery Division, Department of Surgery, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
authors.forename: Junichi
authors.initials: J
authors.lastname: Shindoh
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Mise
authors.forename: Shoichi
authors.initials: S
authors.lastname: Satou
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Sugawara
authors.forename: Norihiro
authors.initials: N
authors.lastname: Kokudo
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008099:Liver / Q000033:anatomy & histology*; D008113:Liver Neoplasms / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D055815:Young Adult