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

Figure 6 Type IIa classification: Bilateral trunk-type left-right subdivision of segment 4. A and B: Axial contrast-enhanced computed tomography images from a representative type IIa case, showing two dominant Glissonean pedicles-Glissonean pedicles of segment 4 L (S4 L) and Glissonean pedicles of segment 4R (S4R)-supplying the left and right subsegments of S4 L and S4R, respectively; C: Three-dimensional portal vein reconstruction confirming a bilateral trunk-type configuration, with independent inflow to S4 L and S4R; D: Schematic diagram illustrating the symmetric left-right portal supply pattern, supporting lateralized subsegmental resection while preserving non-involved liver parenchyma. IB: Intermediate branch; G2: Glissonean pedicles of segment 2; G3: Glissonean pedicles of segment 3; G4: Glissonean pedicles of segment 4.