Three-dimensional volumetry in 107 normal livers reveals clinically relevant inter-segment variation in size

The anatomic resection of Couinaud's segments is one of the key techniques in liver surgery. However, the territories and volumes of the eight segments are not adequately assessed based on portal branching.

Three-dimensional (3D) perfusion-based volumetry was performed in 107 normal livers. Based on Couinaud classification, the portal branches were identified and the volumes of each segment were calculated. The relationships between branching patterns of the portal veins and segmental volumes were assessed.

In descending order of volume, median volumes of segments VIII, VII, IV, V, III, VI, II and I were recorded. Segment VIII was the largest, accounting for a median of 26.1% (range: 11.1-38.0%) of total liver volume (TLV), whereas segments II and III each represented <10% of TLV. In 69.2% of subjects, the portal branches of segment V diverged from the trunk of the branches of segment VIII. No relationship was found between branching type and segment volume.

The territories and volumes of Couinaud's segments vary among segments, as well as among individuals. Detailed 3D volumetry is useful for preoperative evaluations of the dissection line and of future liver remnant volume in anatomic segmentectomy.