Indocyanine green-based fluorescence imaging in visceral and hepatobiliary and pancreatic surgery: State of the art and future directions

Abstract

In recent years, the use of fluorescence-guided surgery (FGS) to treat benign and malignant visceral, hepatobiliary and pancreatic neoplasms has significantly increased. FGS relies on the fluorescence signal emitted by injected substances (fluorophores) after being illuminated by ad hoc laser sources to help guide the surgical procedure and provide the surgeon with real-time visualization of the fluorescent structures of interest that would be otherwise invisible. This review surveys and discusses the most common and emerging clinical applications of indocyanine green (ICG)-based fluorescence in visceral, hepatobiliary and pancreatic surgery. The analysis, findings, and discussion presented here rely on the authors' significant experience with this technique in their medical institutions, an up-to-date review of the most relevant articles published on this topic between 2014 and 2018, and lengthy discussions with key opinion leaders in the field during recent conferences and congresses. For each application, the benefits and limitations of this technique, as well as applicable future directions, are described. The imaging of fluorescence emitted by ICG is a simple, fast, relatively inexpensive, and harmless tool with numerous different applications in surgery for both neoplasms and benign pathologies of the visceral and hepatobiliary systems. The ever-increasing availability of visual systems that can utilize this tool will transform some of these applications into the standard of care in the near future. Further studies are needed to evaluate the strengths and weaknesses of each application of ICG-based fluorescence imaging in abdominal surgery.

Keywords: Biliary anatomy; Biliary surgery; Fluorescence imaging; Gastrointestinal surgery; Indocyanine green; Liver surgery; Pancreatic surgery; Peritoneal carcinomatosis; Visceral perfusion.

Figure 1

Colon perfusion before anastomosis during left colectomy. A few seconds after the i.v. injection of 0.3 mg/kg indocyanine green, bowel arteries clearly appear (A); thereafter, the bowel perfusion cut-off area becomes evident (B and C).

Figure 2

Indocyanine green-enhanced biliary anatomy. During a difficult cholecystectomy for acute cholecystitis (A), the confluence between the cystic duct (CyD) and the common hepatic duct (CHD) is shown by fluorescence imaging (B); common hepatic duct (arrow) is further visualized before (C and D) and after (E and F) cystic duct division. ICG: Indocyanine green.

Figure 3

Indocyanine green in liver surgery. Primary liver tumors show intense and complete staining because their hepatocytes take up ICG but do not secrete it (A and B); liver metastases show a ring appearance because their cells do not take up ICG but hepatocytes surrounding the nodule are compressed (C and D). ICG: Indocyanine green.

Figure 4

Indocyanine green fluorescence imaging in extended right hemicolectomy. The figure displays the right branches of middle colic vessel division during extended right hemicolectomy for transverse colon cancer. ICG injected in the tumor site spreads in nodes at the very proximal root of the artery. ICG fluorescence imaging allows a radical lymphadenectomy, including very small nodes (A and B). Only when all the stained nodes are removed may the nodal dissection be considered radical (C). ICG: Indocyanine green.