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Hidden symmetry in asymmetric morphology: significance of Hjortsjo's anatomical model in liver surgery.

BACKGROUND/AIMS
Several studies have recently reappraised the liver classification proposed by Hjortsjo in the 1940's and reported it as a surgically relevant theory. However, its clinical relevance and significance in liver surgery have not yet been well documented.


METHODOLOGY
Three-dimensional (3D) simulations of the livers of 100 healthy donors for living donor liver transplantation were reviewed. The adequacy of Hjortsjo's model was evaluated using 3D simulations and its clinical relevance was demonstrated in donor surgery.


RESULTS
Both portal and hepatic venous branches exhibited symmetrical configuration on either side of the Rex-Cantlie line on the 3D images. In terms of the symmetry, the right paramedian sector seemed to be subdivided into two longitudinal parts, namely the "ventral" and "dorsal" parts. Volume analysis revealed that these longitudinal parts occupied relatively large areas of the liver (the ventral part, 15.7% and the dorsal part, 20.9% of the whole livers, respectively). Postoperative CT imaging confirmed marked congestion and/or impaired regeneration of these areas due to deprivation of the middle or right hepatic veins.


CONCLUSIONS
Considering the symmetry of intrahepatic vascular distributions and clinical relevance, Hjortsjo's classification offers important viewpoint for surgeons to handle the liver based on both the portal and venous distributions.