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. SUMMARY OF BACKGROUND DATA: 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.
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. SUMMARY OF BACKGROUND DATA: 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.