Perfusion and drainage difference in the liver parenchyma: Regional plane in segment 6

Landmarks to identify segmental borders of the liver: A review prepared for PAM-HBP expert consensus meeting 2021

BACKGROUND

In preparation for the upcoming consensus meeting in Tokyo in 2021, this systematic review aimed to analyze the current available evidence regarding surgical anatomy of the liver, focusing on useful landmarks, strategies and technical tools to perform precise anatomic liver resection (ALR).

METHODS

A systematic review was conducted on MEDLINE/PubMed for English articles and on Ichushi database for Japanese articles until September 2020. The quality assessment of the articles was performed in accordance with the Scottish Intercollegiate Guidelines Network (SIGN).

RESULTS

A total of 3169 manuscripts were obtained, 1993 in English and 1176 in Japanese literature. Subsequently, 63 English and 20 Japanese articles were selected and reviewed. The quality assessment of comparative series and case series was revealed to be usually low; only six articles were qualified as high quality. Forty-two articles focused on analyzing intersegmental/sectional planes and their relationship with specific hepatic landmark veins. In 12 articles, the authors aimed to investigate liver surface anatomic structures, while 36 articles aimed to study technological tools and contrast agents for surgical segmentation during ALR. Although Couinaud's classification has remained the cornerstone in daily diagnostic/surgical practices, it does not always portray the realistic liver segmentation and there has been no standardization on which a single strategy should be followed to perform precise ALR.

CONCLUSIONS

A global consensus should be pursued in order to establish clear guidelines and proper recommendations to perform ALR in the era of minimally invasive surgery.

Simulation of portal/hepatic vein associated remnant liver ischemia/congestion by three-dimensional visualization technology based on preoperative CT scan

Background

Remnant liver hypoperfusion is frequently observed after hepatectomy, and associated with a higher risk of postoperative complications and poorer survival. However, the development of remnant liver hypoperfusion was not fully understood.

Methods

We retrospectively analyzed patients who received hepatectomy and took contrast-enhanced computed tomography (CT) scans before, 1-week (POW1) and 4-week (POW4) after resection in our department from June 2017 to July 2019. We simulated and estimated the occurrence of portal-vein-related remnant liver ischemia (RLI) and hepatic-vein-related remnant liver congestion (RLC) after hepatectomy via three-dimensional visualization technology (3DVT) according to blood vessels ligated in the resection; then we analyzed association between the estimated RLI, RLC, and postoperative clinical outcomes.

Results

A total of 102 eligible patients were analyzed. Remnant liver hypoperfusion was observed in 47 (46%) patients in the POW1 CT scans and shrunk in the POW4 CT scans. RLC had better diagnostic significance than RLI in predicting remnant liver hypoperfusion [area under receiver operating characteristic (ROC) curve: 0.745 vs. 0.569, P=0.026]. Multivariate analysis showed that larger RLI [odds ratio (OR), 1.154; 95% confidence interval (CI), 1.075-1.240; P<0.001] was independent risk factor for post-hepatectomy liver failure (PHLF). Besides, larger RLC (OR, 1.114; 95% CI, 1.032-1.204; P=0.006) was independent risk factor for major postoperative complications.

Conclusions

Remnant liver hypoperfusion can be predicted during the preoperative surgical plan by 3DVT. Portal vein related RLI was associated with PHLF, and hepatic vein related RLC was associated with major postoperative complications. Preservation of the hepatic vein and complete removal of the perfusion territory of ligated vessels are essential procedures to reduce RLI/RLC and the risk of PHLF or other surgical complications.