A Method for Defining Edge Margin Field and Its Application

Yanjin Liu

, Jun Wu, Shuhui Xu and Biao Peng

Faculty of Mechanical Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China

Keywords:

Tumors of Liver, Incisal Edge, Margin Field, Aided Navigation.

Abstract:

Hepatectomy is one of the main treatment methods for liver tumor resection at present. However, the key

technology for accurate navigation and localization of intrahepatic tumors during surgery to achieve the

resection of hepatocellular carcinoma is still unclear. This paper is written for minimally invasive laparoscopic

liver resection of the tumor in the auxiliary navigation technology. This paper provides a method for defining

the margin field of hepatic tumor incision margins and a model system and the application of measuring the

scalpel and tumor distance. The purpose of this paper is to assist physicians in making intraoperative surgical

decisions, correct the surgical path in a timely manner and achieve a low-risk effect of minimally invasive

laparoscopic surgery.

1 INTRODUCTION

Liver cancer is one of the most common malignancies

worldwide. (Habib, 2015) Patients with early-stage

liver cancer can undergo surgical treatment such as

surgical resection, liver transplantation, and tumor

ablation, of which surgical resection is the preferred

treatment option. (Takamoto, 2019) The incidence of

liver cancer ranks sixth in the world's malignant

tumors, and the mortality rate ranks second in the

world's malignant tumors. China is a country with a

high incidence of liver cancer. According to data

released by the World Health Organization in 2015,

there are about 93 million people living with hepatitis

B virus in China, of which 1-5% of patients develop

liver cancer, new cases account for about half of the

world. Liver cancer kills about 300,000 people each

year, including 40% of the elderly. (Journal of

hepatology, 2018; Mareng, 2016; Huang, 2016; Della,

2016)

Before doing liver resection, the surgeon needs to

evaluate the residual remaining liver volume with the

help of preoperative CT liver three-dimensional

reconstruction or physician experience to prevent

excessive liver removal from causing liver failure. In

hepatectomy, the chief surgeon roughly estimates the

incision line according to the preoperative CT image,

with the surgeon's clinical experience and spatial

imagination ability, supplemented by color

ultrasound confirmation and adjustment of the cutting

line. The identification of intrahepatic duct anatomy

in the process of hepatotomy is mainly determined by

the general anatomical cognition of the ischemic line

on the hepatic surface or the clinical experience of the

surgeon to achieve anatomical hepatic resection.

Make sure that the incisional margin is not less than

one centimeter from the surface of the liver tumor.

(Moris, 2018; Yoon, 2017)

There are many effects of margin width on the

postoperative removal of hepatocellular carcinoma.

In general, complete resection of the lesion and

sufficient distance from the lesion is considered

important to ensure eradication of malignancy and to

avoid recurrence as much as possible. One centimeter

margin is sufficient for most liver cancer patients, but

for those who can tolerate a wide range of liver

resection, two centimeter margin can helps to reduce

tumor recurrence.

As we all know, the current difficulty of

laparoscopic liver tumor resection is that: first of all,

most of the ultrasound localization is used to perceive

the two-dimensional image information of the tumor

in the liver, but the depth information of the tumor

cannot be determined. And the surgeon in the

operation cannot accurately determine the relative

position relationship between the tumor and the blood

vessel due to the lack of three-dimensional

information inside the liver. The above two

difficulties may lead to the surgeon removing excess

liver or incomplete tumor cutting so that there is no

guarantee of optimal trajectory to remove the liver

Liu, Y., Wu, J., Xu, S. and Peng, B.

A Method for Deﬁning Edge Margin Field and Its Application.

DOI: 10.5220/0012020500003633

In Proceedings of the 4th International Conference on Biotechnology and Biomedicine (ICBB 2022), pages 325-328

ISBN: 978-989-758-637-8

 2023 by SCITEPRESS – Science and Technology Publications, Lda. Under CC license (CC BY-NC-ND 4.0)

325

tumor. It increasing the risk of surgery and prolonging

the operation time.

Aiming at the problems of high surgical risk and

long surgical time during liver tumor resection in

existing techniques, this paper proposes a method for

establishing a marginal field model for tumor

resection and the application of measuring the

distance between scalpel and tumor during liver

resection surgery.

2 SOFTWARE AND METHODS

FOR 3D RECONSTRUCTION

OF DICOM IMAGING DATA

2.1 Software

Design and simulation of 3D virtual liver surgery

based on CT scan data, the 64-row thin layer scanning

dataset of the patient's abdominal liver was collected.

In this paper, Mimics software developed by the

Belgian company Materialise was used for three-

dimensional reconstruction of the liver, intrahepatic

tumors and their intrahepatic blood vessels.

2.2

The Basic Steps of Modeling

Medical Image Processing Software

Mimics

DICOM data read: We first imported a standard

Dicom3.0 format image file formed from more than

400 CT scans of the patient's abdomen into Mimics

software. After receiving the command, the software

will automatically generate coronal and sagittal

images based on the cross-sectional images, which

are shown separately in Fig. 1.

Threshold profile extraction and three-

dimensional reconstruction: Due to the different CT

values of different tissues, the CT difference between

the corresponding tissues and organs themselves is

small and the difference with other surrounding

tissues and organs is large, so that use the threshold

setting tool in the toolbar to set the corresponding

threshold to segment the image. Mimics will split all

the pixels extracted under a template called Mask, and

Mimics will provide a series of editing and

modification operations for this template to extract

and refine the required tissues and organs. By editing

the template, we can do 3D modeling to achieve the

transformation from a 2D image to a 3D solid, as

shown in the lower right corner of Fig. 1. (Mi, 2021)

Figure 1: Three-dimensional images reconstructed after the patient CT was imported into Mimics.

3 A METHOD FOR DEFINING

THE MARGIN FIELD OF

HEPATIC TUMOR INCISION

MARGINS

3.1 Define the Method

The envelope is a convex surface that tightens the

tumor. After the threshold segmentation extraction of

the intra-abdominal tumor by Mimics software, the

model of the tumor is exported, and the contour of the

outer surface of the tumor is known to be uneven, and

the surface of the concave area on the tumor surface

is first obtained by the convex surface of the tumor

surface algorithm to obtain a convex surface model of

the tight enveloping tumor, and the convex surface

obtained by smoothing it is the envelope surface of

the tumor, as shown in Figure 2(a).

Then, a point A is randomly selected on the

envelope surface, the crossing point A is the tangent

plane Σ of the envelope surface, and the straight line

segment perpendicular to the tangent plane Σ is the

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normal segment at a certain point A on the envelope

surface. By analogy, taking all the points on the tumor

envelope as the starting point, each point on the

envelope surface is made perpendicular to the normal

segment of the tangent plane Σi at the point, the length

of the normal segment is set as 1cm per unit length,

and finally a new convex surface composed of the end

point of the unit length normal segment is obtained,

so that the new convex surface is defined as a tangent

edge surface 1cm away from the tumor outer network,

and its principle is regarded as the uniform expansion

deformation of the tumor model. In summary, the

outward expansion deformation is based on all the

points on the envelope surface, and the convex

surface that expands and deforms by 1 cm is defined

as the tangent edge surface of the tumor. The distance

from any point on the cut edge surface to the tumor

should be no less than 1 cm, as shown in Fig. 2(a).

Finally, based on the envelope surface isometric

expansion to obtain a plurality of convex surfaces,

consisting of a plurality of progressively deformed

and expanded convex surfaces of the field, we define

it as the margin field of the tumor, wherein the

interval between each surface of the margin field is 1

cm, as shown in Figure 2 (b), the distance from the

above-mentioned cut edge surface to the tumor

surface contour is 1 cm, the cut edge surface is the

tumor 1 cm margin field.

(a) (b) (c)

Figure 2: The outer contour surface, envelope surface, and marginal field of the tumor.

3.2 Distance Calculation Application

Between Scalpel and Tumor Based

on Margin Margin Field

In the future minimally invasive liver tumor resection,

robot technology will be continuously introduced for

the requirements of accurate removal of liver tumors,

and under the motion simulation model based on

robot surgical action, the definition and visualization

of the margin field provide the robot with distance

parameters to know the distance d of the scalpel and

the tumor boundary. According to the distance

between the margin field and the envelope surface, it

is named, as shown in Fig. 2(c). Such as 1cm margin

field, 2cm margin field and 3cm margin field, etc.

Assuming that the scalpel head is located between the

2cm to 3cm margin field in the simulation model of

robot motion, it is obvious that the distance from the

scalpel head to the tumor is 2 to 3cm. In summary, the

definition of marginal field can be used in future

robotic minimally invasive surgery to measure the

distance between the scalpel and the intrahepatic

tumor, providing auxiliary guidance for physicians

when removing the tumor during surgery, and

avoiding the risk of surgery caused by the scalpel

touching the tumor.

3.3

Establishment System for Marginal

Fields

Fig. 3 Further provides an establishing module for

tumor margin margin field, comprising: establishing

module 1, determining module 2, envelope creation

module 3 and determining module 4. Wherein, the

establishment of module 1 for obtaining the patient's

imaging data, through the three-dimensional

reconstruction of the body data to obtain a model of

the relative position relationship between the tissues;

judgment module 2, for calling the relative position

information between the tumor and other tissues to

determine the resectability of the tumor, if yes

(intrahepatic tumor has resectability), into the

envelope creation module 3, if not, end; the envelope

creation module is used to establish an envelope

surface according to the external contour information

of the tumor surface, the envelope surface is the

convex envelope of the tumor; determine module 4, It

is used to determine the tumor 1 cm margin and

margin

field based on the envelope surface of the

A Method for Deﬁning Edge Margin Field and Its Application

327

Figure 3: The overall structure diagram of the system for the establishment of tumor margin field.

tumor. According to the model established by the

system, the situation of intrahepatic tumors in the

human body is effectively simulated, and then

according to the location relationship between tumors

and intrahepatic blood vessels in the liver, a

reasonable anatomical direction is selected to

determine how to achieve complete resection of

tumors with the purpose of minimizing liver damage.

4 CONCLUSION

In this paper, we first elaborate on the global impact

of liver cancer incidence and the limitations of

treatment strategies and surgical treatment options,

and then propose the establishment method and

distance measurement application of a tumor excision

margin field model for the reasons why it is difficult

to know the depth of intrahepatic tumor information,

resulting in greater surgical risk and long surgical

time.

This paper analyzes the three-dimensional

reconstruction process of CT body data of Mimics

software, and it can be seen that Mimics can well

display the corresponding three-dimensional anatomy

of the human body, so that doctors can make detailed,

reasonable and accurate disease diagnosis; this paper

also provides a definition method and establishment

system of tumor margin margin field; finally

describes the application of tumor margin margin

field to measure the distance between scalpel and

tumor in future robotic minimally invasive surgery,

based on the scalpel in real time positioning feedback

information in the three-dimensional model. In this

way, it assists physicians in making intraoperative

decisions, can change the surgical path in time, and

finally achieves accurate resection of lesion areas in

robot-assisted liver tumor resection and achieves low-

risk surgical results.

ACKNOWLEDGMENTS

This research was supported by the Natural Science

Foundation of Shandong Province (Application No.

ZR202109280010).

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