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Thiruchelvam et al. Hepatoma Res 2021;7:22 I http://dx.doi.org/10.20517/2394-5079.2020.144 Page 15 of 18

A B

Figure 12. Hand-assisted laparoscopic approach for right and left hepatectomy. Hand-assisted right hepatectomy (A). Hand-assisted
left hepatectomy (B).

application of existing LLR difficulty scores will help surgeons tailor their level of experience accordingly,
to the appropriate resection that they should embark on safely [58-61] . Another guiding tool that is important,
yet under-described, is the art and science of optimal patient and port positioning.

Currently, three-dimensional (3D) simulation software such as SYNAPSE VINCENT volume analyzer
(Fujifilm Co., Tokyo, Japan) allows conversion of computer tomography liver images into 3D imagery,
facilitating precise and parenchymal-saving resections by providing a detailed analysis of subsegmental
inflow vessels and venous drainage. Moreover, real-time virtual sonography (RVS) provides a reconstructed
CT image, which can be utilised to precisely identify structures in the planned resection line and ensure
safe resection margins. Looking forward, a technology that may potentially enhance LLR is the use of 3D
virtual resection planning integrated with augmented reality (AR), such that surgeons can be provided with
imagery that is transposed live into the operative field. At the current moment, the use of AR as an intra-
operative navigation tool is limited because reference CT or 3D images are rigid and unable to synchronize
accurately with the natural deformation of liver parenchyma that occurs during liver mobilisation and
[48]
parenchymal transection. Hallet et al. describe the use of AR for trans-thoracic trans-diaphramatic
resection of a dome lesion that involved minimal liver deformation, and hence facilitated ideal intercostal
port placement and precise diaphragmatic incisions. As technology advances in the future, it may allow for
enhanced planning of patient positioning and port placements, and facilitate more precise parenchymal
resections.

DECLARATIONS
Acknowledgments
The authors acknowledge Mr Ravin Thiruchelvam (ravin.light@gmail.com) for image editing.

Authors’ contributions
Made substantial contributions to conception of the article, drafting of the article and material support:
Thiruchelvam N