Demarcating the Exact Midplane of the Liver Using Indocyanine Green Near-Infrared Fluorescence Imaging During Laparoscopic Donor Hepatectomy

Repurposing indocyanine green: exploring the potential of an old drug in modern medicine

The repurposing of existing drugs, referred to as theranostics, has made profound impacts on precision medicine. Indocyanine green (ICG), a well-established and clinical dye, has continued to be a star agent, described as a multifunctional molecule with concurrent photo- or sono-sensitiveness capabilities and co-delivery accessibility, showing remarkable potential in the area of unimodal or multimodal imaging-guided therapy of various diseases, leading to the extensive consideration of immediate clinical translations. In this review, we strive to bring the understanding of repurposing performance assessment for ICG into practice by clarifying the relationships between its features and applicability. Specifically, we address the obstacles encountered in the process of developing an ICG repurposing strategy, as well as the noteworthy advancements made in the field of ICG repurposing. We also go into detail about the structure-function correlations of drugs containing ICG and how different structural groups significantly affect the physicochemical properties.

Use of Fluorescence Imaging in Liver Transplant Surgery

Liver transplant surgery is a complex procedure that demands high knowledge of surgical anatomy and the precise recognition and preservation of structures. To address this, the use of fluorescence imaging has facilitated the identification of anatomical structures such as biliary ducts, arteries, and liver segmentation. Indocyanine green is among the most commonly utilized fluorescent agents, not just during surgery but also in the pre- and postoperative phases, where it is used to assess graft failure by measuring the plasma disappearance rate. New advancements such as artificial intelligence paired with fluorescence imaging have the potential to enhance patient outcomes. Additionally, technologies such as augmented reality and mixed reality could be integrated into surgical procedures, broadening the scope of possibilities for improving patient safety.

Pure laparoscopic donor hepatectomy: Experience of 556 cases at Seoul National University Hospital

Pure laparoscopic donor hepatectomy (PLDH) has become a routine procedure at Seoul National University Hospital, and the pure laparoscopic method is now being applied to liver recipients as well. This study aimed to review the procedure and outcomes of PLDH to identify any areas that required improvement. Data from 556 donors who underwent PLDH between November 2015 and December 2021 and their recipients were retrospectively reviewed. Among these, 541 patients underwent pure laparoscopic donor right hepatectomy (PLDRH). The mean hospital stay of the donor was 7.2 days, and the rate of grade I, II, IIIa, and IIIb complications was 2.2%, 2.7%, 1.3%, and 0.9%, respectively, without any irreversible disabilities or mortalities. The most common early and late major complications in the recipient were intraabdominal bleeding (n = 47, 8.5%) and biliary problems (n = 198, 35.6%), respectively. Analysis of the PLDRH procedure showed that operative time, liver removal time, warm ischemic time, Δhemoglobin%, Δtotal bilirubin%, and postoperative hospital stay decreased significantly as the number of cases accumulated. In conclusion, the operative outcomes of PLDRH improved as the number of cases increased. However, continuous caution is needed because major complications still occur in donors and recipients even after hundreds of cases.

Quantification of Indocyanine Green Fluorescence Imaging in General, Visceral and Transplant Surgery

Near-infrared (NIR) imaging with indocyanine green (ICG) has proven to be useful in general, visceral, and transplant surgery. However, most studies have performed only qualitative assessments. Therefore, a systematic overview of all studies performing quantitative indocyanine green evaluation in general, visceral, and transplant surgeries should be conducted. Free term and medical subject heading (MeSH) term searches were performed in the Medline and Cochrane databases until October 2022. The main categories of ICG quantification were esophageal surgery (24.6%), reconstructive surgery (24.6%), and colorectal surgery (21.3%). Concordantly, anastomotic leak (41%) was the main endpoint, followed by the assessment of flap perfusion (23%) and the identification of structures and organs (14.8%). Most studies examined open surgery (67.6%) or laparoscopic surgery (23.1%). The analysis was mainly carried out using manufacturer software (44.3%) and open-source software (15.6%). The most frequently analyzed parameter was intensity over time for blood flow assessment, followed by intensity alone or intensity-to-background ratios for structure and organ identification. Intraoperative ICG quantification could become more important with the increasing impact of robotic surgery and machine learning algorithms for image and video analysis.

Added value of indocyanine green fluorescence imaging in liver surgery

Recently, indocyanine green (ICG) fluorescence imaging has been widely used as a substitute for cholangiography in hepatobiliary surgery, to detect hepatic tumors, for accurate anatomical hepatectomy, and to increase the safety and accuracy of minimally invasive (laparoscopic and robotic) hepatectomy. The clinical relevance of this method has been increasing gradually, as new procedures develop in this field. Various important roles and the latest added value of ICG fluorescence imaging in liver surgery are discussed in this report.

Indocyanine Green Fluorescence Navigation in Liver Surgery: A Systematic Review on Dose and Timing of Administration

BACKGROUND

Indocyanine green (ICG) fluorescence has proven to be a high potential navigation tool during liver surgery; however, its optimal usage is still far from being standardized.

METHODS

A systematic review was conducted on MEDLINE/PubMed for English articles that contained the information of dose and timing of ICG administration until February 2021. Successful rates of tumor detection and liver segmentation, as well as tumor/patient background and imaging settings were also reviewed. The quality assessment of the articles was performed in accordance with the Scottish Intercollegiate Guidelines Network (SIGN).

RESULTS

Out of initial 311 articles, a total of 72 manuscripts were obtained. The quality assessment of the included studies revealed usually low; only 9 articles got qualified as high quality. Forty articles (55%) focused on open resections, whereas 32 articles (45%) on laparoscopic and robotic liver resections. Thirty-four articles (47%) described tumor detection ability, and 25 articles (35%) did liver segmentation ability, and the others (18%) did both abilities. Negative staining was reported (42%) more than positive staining (32%). For tumor detection, majority used the dose of 0.5 mg/kg within 14 days before the operation day, and an additional administration (0.02-0.5 mg/kg) in case of longer preoperative interval. Tumor detection rate was reported to be 87.4% (range, 43%-100%) with false positive rate reported to be 10.5% (range, 0%-31.3%). For negative staining method, the majority used 2.5 mg/body, ranging from 0.025 to 25 mg/body. For positive staining method, the majority used 0.25 mg/body, ranging from 0.025 to 12.5 mg/body. Successful segmentation rate was 88.0% (range, 53%-100%).

CONCLUSION

The time point and dose of ICG administration strongly needs to be tailored case by case in daily practice, due to various tumor/patient backgrounds and imaging settings.

Essential updates 2020/2021: Current topics of simulation and navigation in hepatectomy

With the development of three‐dimensional (3D) simulation software, preoperative simulation technology is almost completely established. The remaining issue is how to recognize anatomy three‐dimensionally. Extended reality is a newly developed technology with several merits for surgical application: no requirement for a sterilized display monitor, better spatial awareness, and the ability to share 3D images among all surgeons. Various technology or devices for intraoperative navigation have also been developed to support the safety and certainty of liver surgery. Consensus recommendations regarding indocyanine green fluorescence were determined in 2021. Extended reality has also been applied to intraoperative navigation, and artificial intelligence (AI) is one of the topics of real‐time navigation. AI might overcome the problem of liver deformity with automatic registration. Including the issues described above, this article focuses on recent advances in simulation and navigation in liver surgery from 2020 to 2021.