# Endoscopic Tattooing Using Indocyanine Green (ICG) Fluorescence for Intraoperative Guidance in Colorectal Surgery: Review of the Literature

## TL;DR

This paper reviews how using indocyanine green (ICG) in endoscopic tattooing helps surgeons locate colorectal tumors and improve lymph node removal during surgery.

## Contribution

The paper systematically reviews the use of ICG-based tattooing for intraoperative guidance in colorectal surgery and its impact on lymphadenectomy.

## Key findings

- ICG tattooing improves intraoperative tumor localization rates.
- Fluorescent guidance increases lymph node yields during lymphadenectomy.
- Current protocols for ICG tattooing lack standardization and have notable limitations.

## Abstract

Indocyanine green (ICG) has been recently described in endoscopic tattooing of colorectal lesions treated with curative-intent surgery combined with near-infrared laparoscopic and robotic platforms. Our systematic review of the literature has focused on its utility in intraoperative tumor identification rates, and in identifying tumor-associated lymphatic drainage and performing radical lymphadenectomy. We have also described protocols used in timing and dosages used in ICG-based tattooing as well as associated adverse events. Significant potential benefits in all aforementioned aspects have been noted. However, existing data suffer from significant limitations.

Background and Objectives: Accurate endoscopic lesion localization is crucial for planning and performing curative-intent surgery in colorectal cancer management. The use of indocyanine green (ICG) has been described as a novel alternative for colorectal lesion marking. Materials and Methods: We have performed a systematic review of the literature on the use of ICG-based tattooing for patients with colorectal cancer undergoing surgery. Results: A total of 19 studies were identified. Seven studies reposted the rates of successful intraoperative localization following ICG tattooing. Additionally, six studies provided detailed descriptions of the administration protocols, including both timing and dosage. A total of twelve studies described the utility of ICG-based tattooing for subsequent lymphadenectomy and its oncologic implications. Lymphadenectomy under fluorescent guidance was associated with increased lymph node yields as well as a change to the surgical lymphadenectomy plan in a significant proportion of patients. Conclusions: ICG-based endoscopic tattooing has demonstrated significant value in facilitating precise lesion localization during curative-intent colorectal surgery. Moreover, its use has been extended to guiding lymphadenectomy, with reports indicating improved lymph node yields. Nevertheless, further research is required to standardize protocols and address existing limitations.