Precision surgery for primary liver cancer

Abstract

Liver resection remains the best curative option for primary liver cancer, such as hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma. In particular, in liver resection for HCC, anatomical resection of the tumor-bearing segments is highly recommended to eradicate the intrahepatic metastases spreading through portal venous branches. Anatomical liver resection, including anatomical segmentectomy and subsegmentectomy using the dye-injection method, is technically demanding and requires experience for completion of a precise procedure. The recent development of imaging studies and new computer technologies has allowed for the preoperative design of the operative procedure, intraoperative navigation, and postoperative quality evaluation of the anatomical liver resection. Although these new technologies are related to the progress of artificial intelligence, the actual operative procedure is still performed as human-hand work. A precise anatomical liver resection still requires meticulous exposure of the boundary of hepatic venous tributaries with deep knowledge of liver anatomy and utilization of intraoperative ultrasonography.

Keywords: Preoperative ultrasonic examination; anatomical liver resection; dye injection method; intraoperative ultrasonography; preoperative imaging.

1

Flowchart of our preparation and decision-making for precision surgery for primary liver cancer. HCC, hepatocellular carcinoma; FRL, future remnant liver; ICG, indocyanine green.

2

Decision tree for selection of operative procedures. There are three important factors, i.e. ascites, serum total bilirubin value and indocyanine green (ICG) retention rate at 15 minutes (ICGR15) or ICG-K values. For patients with uncontrollable ascites or having serum total bilirubin level over 2.0 mg/dL, hepatectomy will not be proceeded.

3

Schema of hepatocellular carcinoma’s extension. (A) Tumor invades into portal venous branches and tumor cells are carried to the distal part of the liver by portal venous flow. (B) The carried tumor cells will grow into microscopic tumor thrombus and then into daughter nodules or intrahepatic metastasis. (C) The tumor thrombus becomes a source of wider tumor spread. Reprinted with permission from Ref. .

4

Procedure of anatomical resection with dye-injection method. Tumor-bearing segment or subsegment is stained by injecting dye under the guide of ultrasound, then the stained area is marked. Under intermittent inflow occlusion, liver parenchyma is divided. And the root of portal pedicle and landmark veins are fully exposed on the surface of the resection plane. Anatomical resection is only one choice of treatment for obtaining radicality. Reprinted with permission from Ref. .

5

Individual differences of segments (S8dor). The stained area of S8dor was shown in two cases (A/B). Naturally, the shape and volume of each liver segments differs case by case.

6

Individual differences of liver raw surface after segmentectomy (S7). The appearances of liver raw surface after S7 segmentectomy of two cases were compared. There are difference in the shape of liver resection surface and positions of each landmarks (A/B). Additionally, when a patient has inferior right hepatic vein, it is be exposed on the caudal boundary surface (A).

7

A case who received anatomical segmentectomy of S6 with dye-injection method. Indigocarmine solution was injected into portal branch of segment six and S6 was stained (A). On the liver resection surface after S6 anatomical resection, two tributaries of right hepatic veins are clearly exposed (B). Resections of peripheral liver such as S6 are considered to have good indication for laparoscopic hepatectomy, but it is quite difficult to expose the hepatic veins so clearly in laparoscopic hepatectomy. There is little possibility that the laparoscopic hepatectomy shows stronger impact on prognosis than open hepatectomy for the surgical treatment of HCC.

8

Clear exposure of major hepatic veins is the evidence of complete anatomical resection. Every major hepatic vein was exposed with half circumference in right paramedian sectorectomy (A), right lateral sectorectomy (B), left hepatectomy (C), and right hepatectomy (D). The rough liver resection plane is the evidence that the intersegmental plane of the liver is not flat.

9

Procedure of right hepatectomy with exposure of minute peripheral hepatic veins. From 0.5 to 1 cm from the liver surface, a small hepatic venous tributary is found (A). Liver transection is proceeded following the tributary, then thicker hepatic veins appear (B). Several hepatic venous tributaries drainaging right liver were carefully ligated and divided (D), then the liver transection plane consistently meets the main trunk of middle hepatic vein (E). On the liver resection plane, the middle hepatic vein and its tributaries were clearly exposed from the liver surface to the confluence of inferior vena cava.