Portal vein-based subsegmental classification of liver segment four for parenchyma-sparing laparoscopic resection: A retrospective study

Figure 7 Type IIb classification: Unilateral trunk with contralateral dispersion in left-right subdivision of segment 4. A-C: Axial contrast-enhanced computed tomography images from a representative type IIb case. A dominant Glissonean pedicles of segment 4 (G4; G4R) supplies the right subsegment of segment 4 (S4; S4R), while the left subsegment (S4 L) receives multiple fine and scattered branches (G4 L), without a dominant trunk; D: Three-dimensional portal vein reconstruction confirming the asymmetric left-right perfusion pattern, with a single structured G4R pedicle and dispersed G4 L branches; E: Schematic diagram illustrating the type IIb anatomy, characterized by unilateral trunk-type inflow to S4R and contralateral scattered inflow to S4 L. G4: Glissonean pedicles of segment 4.