Towards real-time tumor margin assessment in colorectal liver metastases surgery using near-infrared fluorescence-imaging

Master thesis (2021)

Authors

T.H. Dijkhuis Mechanical Engineering

Contributors

J.S.D. Mieog Biomechanical Engineering (supervisor 1)
J Dijkstra Leiden University Medical Center (supervisor 1)
O.D. Bijlstra Leiden University Medical Center (supervisor 1)
Alexander Broersen Leiden University Medical Center (supervisor 1)
J. Harlaar Biomechatronics & Human-Machine Control - Mechanical, Maritime and Materials Engineering (supervisor 2)
Faculty
Mechanical Engineering
Copyright: © 2021 Tom Dijkhuis
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Published Date

01-10-2021

Language

English

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Faculty

Mechanical Engineering

Abstract

Introduction
Near-infrared fluorescence (NIRF) imaging is a relatively novel development in colorectal liver metastases (CRLM) surgery which has proven to be an added value for the detection of new lesions and surgical guidance. However, new possibilities of NIRF imaging in CRLM surgery are yet to be explored. The fluorescent rim of indocyanine green (ICG) surrounding CRLM can potentially be used to predict the resection margin. By predicting the resection margin, irradical resections can be observed during surgery. Additional tissue can be removed intraoperatively, probably resulting in improved outcomes. This research describes a method to analyze the data retrieved at the Department of Pathology. The goal of this thesis is to provide a verdict on whether ICG could be used as a quantitative indicator for distance to the tumor and therefore, help the surgeon to evaluate the resection margin on-site.

Materials & Methods
Data was collected by imaging bread loaves from resected CRLM. Methods to generate data from these images, to evaluate the collected data, and to evaluate the interobserver error were described. The data were evaluated with the use of general and histogram parameters. Moreover, the data was separated four times into different groups. These groups aimed to investigate the general distribution of ICG around CRLM and the effect of tumor and patient-specific characteristics. Subsequently, the results of the data analysis were used to make a rough estimation of the expected measured fluorescence intensities during surgery.

Results
The interobserver error was 0.9 or higher (Sørensen-Dice coefficient) for 8 out of the 10 delineation pairs including three pairs with a coefficient of 0.95 or higher. However, two pairs of delineations showed coefficients of 0.566 and 0.797. 33 bread loaves were included in this research for data analysis of the general and histogram parameters. Various distributions of ICG around the tumors were found for the groups varying in tumor and patient characteristics. Moreover, differences between groups in general parameters were observed. The rough estimation of the expected measured fluorescence intensity showed a peak intensity around 5 millimeters from the tumor.

Discussion
The delineation of CRLM proved to be a reproducible operation in most of the delineations (80%). However, there is a need for ground truth delineations to examine the accuracy of delineations. Besides, the effects of chemotherapy, the location of the tumor, and the size of the tumor on the peritumoral fluorescent rim, as well as the flaws of this research were discussed.

Future recommendations
Additional research must be performed to be able to develop a method to evaluate resection margins intraoperatively. Future research should focus on the formulation of an implementation plan and the development of the database, the MeVisLab network, the resection margin prediction method, and a protocol that enables the opportunity to create ground truth delineations.

Conclusion
This study showed the potential of the use of the peritumoral fluorescent rim to develop a method that can predict resection margins of resected CRLM intraoperatively. However, additional research must be performed to accurately implement the method and to increase its accuracy.