Anatomical Boundary Between the Caudate Lobe of the Liver and Adjacent Segments Based on Three-Dimensional Analysis for Precise Resections.

BACKGROUND: Right hemihepatectomy or systematic resection of segment 7 or 8 involves partial resection of the paracaval portion of the caudate lobe. However, the boundary between the caudate lobe and segment 7 or 8 remains unclear. We examined the anatomical territory of the caudate lobe with special reference to the boundary between the paracaval portion and segment 7 or 8 for precise anatomical hepatectomies.

METHODS: We enrolled 63 consecutive healthy donor candidates for living-donor liver transplantation from 2012 to 2014 in this study. The caudate lobe was defined according to Kumon's subdivision system, and the boundary between the paracaval portion and segment 7 or 8 was investigated based on three-dimensional computed tomography scan images using SYNAPSE VINCENT® .

RESULTS: The paracaval portion of the liver protruded on the liver surface underneath the right diaphragm on the ventral side of the right hepatic vein (RHV) in 10 participants (16%) and on the dorsal side of the RHV in 9 participants (14%). A branch of the RHV, the "paracaval vein," was found in all 63 participants and ran longitudinally along the right border of the paracaval portion (n = 30, 48%) and within segment 7 (n = 16, 25%) or segment 8 (n = 17, 27%).

CONCLUSIONS: The paracaval portion of the liver protruded on the liver surface underneath the right diaphragm in one third of our participants. The paracaval vein can be a landmark for the boundary between the caudate lobe and the segment 7 or 8 in half of the cases.