The Tokyo 2020 terminology of liver anatomy and resections: updates of the Brisbane 2000: system
| Terminology | Definition |
| Anatomical liver resection | Complete removal of the liver parenchyma confined within the responsible portal territory. |
| Segmentectomy | The complete removal of a territory (territories) of the third-order portal venous branches of a Couinaud segment. |
| Subsegmentectomy | The removal of the liver parenchyma within the portal territory (territories) of less than a Couinaud’s segment. These are also defined as cone units, and their areas can be intraoperatively assessed by using ischaemic demarcation, ICG (negative/ positive) staining, or both. |
| A subsegment | An anatomical portion of a Couinaud segment, which is defined as a cone unit or cone units, based on subsegmental inflow. This concept particularly adapts to Sg 8 (ventral and dorsal), Sg 4 (basal and apical) and Sg 1 (Spiegel, caudate process and paracaval). |
| Segment 4 | Redefined as consisting of two subsegments: Sg 4a (apical) and 4b (basal). Sg 4a is defined as the cranial anatomical portion of Sg 4 according to the third-order portal territories, and Sg 4b is the caudal anatomical portion of Sg 4. |
| Segment 9 | Sg 9 definition of the Brisbane 20005 terminology is abandoned, and caudate lobe is redefined based on portal ramifications instead of spatial recognition. |
| Segment 1 | Classified into three parts as follows: (1) the Spiegel lobe, (2) the paracaval portion and (3) the caudate process. |
ICG, indocyanine green.