Mechanism of dynamic near-infrared fluorescence cholangiography of extrahepatic bile ducts and applications in detecting bile duct injuries using indocyanine green in animal models

Real-time fluorescence imaging with indocyanine green during laparoscopic duodenum-preserving pancreatic head resection

BACKGROUND

Laparoscopic duodenum-preserving pancreatic head resection (LDPPHR) is a surgical method used to treat benign and low-grade malignant pancreatic head tumors. This study aimed to determine the protective effect of common bile duct in LDPPHR using indocyanine green (ICG) fluorescence imaging.

METHODS

A retrospective analysis of 30 patients treated with LDPPHR at the Second Affiliated Hospital of Nanchang University between January 2015 and November 2022 was performed. Patients were divided into two groups based on ICG use: ICG and non-ICG.

RESULTS

Thirty patients received LDPPHR, 11 males and 19 females, and the age was 50.50 (M (IQR)) years (range: 19-76 years). LDPPHR was successfully performed in 27 (90 %) patients, LPD was performed in 1 (3 %) patient, and laparotomy conversion was performed in 2 (7 %) patients. One patient (3 %) died 21 days after surgery. The incidence of intraoperative bile duct injury in the ICG group was lower than that in the non-ICG group (10 % vs 60 %, P = 0.009), and the operation time in the ICG group was shorter than that in the non-ICG group (311.9 ± 14.97 vs 338.05 ± 18.75 min, P < 0.05). Postoperative pancreatic fistula occurred in 16 patients (53 %), including 10 with biochemical leakage (62.5 %), four with grade B (25 %), and two with grade C (12.5 %). Postoperative bile leakage occurred in four patients (13 %).

CONCLUSIONS

The ICG fluorescence imaging technology in LDPPHR helps protect the integrity of the common bile duct and reduce the occurrence of intraoperative bile duct injury, postoperative bile leakage, and bile duct stenosis.

Indocyanine green fluorescent cholangiography improves the clinical effects of difficult laparoscopic cholecystectomy

BACKGROUND

Near-infrared fluorescent cholangiography (NIRFC) with indocyanine green (ICG) as the developer yields clear visualization of the extrahepatic bile ducts and is effective in identifying key structures. Here, we analyzed and compared the surgical outcomes of fluorescent and conventional laparoscopy in cholecystectomy of various difficulties and then assessed the value of NIRFC.

MATERIALS AND METHODS

This retrospective study collected clinical data from partial patients who underwent laparoscopic cholecystectomy (LC) at the Department of Hepatobiliary and Pancreatic Surgery, Zhongnan Hospital of Wuhan University between 2020 and 2021. The study subjects were classified into ICG-assisted and white-light laparoscopy. Two cohorts with homogeneous baseline status were selected based on 1:1 ratio propensity score matching (PSM). Multivariate logistic regression analysis was performed to predict independent risk factors for LC difficulty. Thereafter, the matched cases were classified into difficult and easy subgroups by combining difficulty score and gallbladder disease type, and then the surgical outcomes of the two groups were compared.

RESULTS

This study included a total of 624 patients. The patients were classified into the ICG group (n = 218) and the non-ICG group (n = 218) after a 1:1 ratio PSM. Our data showed significant differences between the groups in operative time (P = 0.020), blood loss (P = 0.016), length of stay (P = 0.036), and adverse reaction (P = 0.023). Stratified analysis demonstrated that ICG did not significantly improve the surgical outcomes in simple cases (n = 208). On the other hand, in difficult cases (n = 228), NIRFC shortened operative time (P = 0.003) and length of stay (P = 0.015), reduced blood loss (P = 0.028) and drain placement rate (P = 0.015), and had fewer adverse reactions (P = 0.023). The data showed that five cases were converted to laparotomy while two cases had minor bile leaks in the non-ICG group. There was no bile duct injury (BDI) in all the cases. Furthermore, high BMI, history of urgent admission and abdominal surgery, palpable gallbladder, thickened wall, and pericholecystic collection were risk factors for surgical difficulty.

CONCLUSION

ICG-assisted NIRFC provides real-time biliary visualization. In complicated conditions such as acute severe inflammation, dense adhesions, and biliary variants, the navigating ability of fluorescence can enhance the operation progress, reduce the possibility of conversion or serious complications, and improve the efficiency and safety of difficult LC.

Indocyanine green real-time-guided laparoscopic duodenum-preserving pancreatic head resection

Duodenum-preserving pancreatic head resection (DPPHR) is very complicated due to its difficulty to find the lower common bile duct (CBD), and to preserve the blood supply of the duodenum and CBD. Recently, indocyanine green (ICG) has been widely applied for navigation during biliary system and liver surgery. However, the application of ICG-guided laparoscopic DPPHR has not been established. Herein, we report an intraoperative angiography technique using ICG fluorescence imaging to visualise blood flow, tissue perfusion, CBD navigation and bile leakage assessment.

Study of Learning Curve in a Surgeon for Near-Infrared Fluorescence Cholangiography During Laparoscopic Cholecystectomy-A Retrospective Evaluation

BACKGROUND

Near-infrared indocyanine green fluorescence cholangiography (NIRF) has shown promising results on delineating extra-hepatic biliary anatomy during laparoscopic cholecystectomy to avoid bile duct injury. However its routine usage remains in question. In this study, the technique was evaluated further with learning curve estimation and learning factors were observed.

METHODS

One hundred ninety-nine cases which underwent laparoscopic cholecystectomy for acute or chronic cholecystitis within a 2-year period including 51 cases with initial use of NIRF by 2 surgeons were studied retrospectively. The learning curve was evaluated for a surgeon as primary objective. A case-matched comparison of the operative time between NIRF and conventional group, in terms of acute and chronic cholecystitis was also conducted as a secondary calculation.

RESULTS

Learning curve was evaluated with 61% learning rate for NIRF experience. Cysto-biliary junction non-illuminated cases under fluorescent view, had mean operative time of 80.83 ± 22.82 min, which was shorter than the cysto-biliary junction illuminated cases. The NIRF group exhibited longer operative time compared with the conventional group with mean difference of 34.39 min (significant at P < .05).

CONCLUSIONS

While the initial learning phase might be affected by surgeons' behavior and attitude, our results may provide a reference to learn at one's own pace and to employ NIRF teaching strategies during surgical training programs to overcome the initial phase during training period itself and facilitate universal achievement.

Fine-scale visualizing the hierarchical structure of mouse biliary tree with fluorescence microscopy method

The liver is a vital organ and the hepatic lobule serves as the most basic structural and functional unit which is mainly assembled with parenchymal cells including hepatocytes and biliary epithelial cells. The continuous tubular arrangement of biliary cells which constitutes the biliary tracts is critical for liver function, however, the biliary tracts are often disrupted in many liver diseases such as cirrhosis and some congenital disorders. Visualization of the biliary tracts in fine-scale and three-dimension will help to understanding the structure basis of these liver diseases. In the present study, we established several biliary tract injury mouse models by diet feeding, surgery or genetic modification. The cytoplasm and nuclei of the parenchymal cells were marked by active uptake of fluorescent dyes Rhodamine B (red) and Hoechst (blue), respectively. After the removal of liver en bloc, the biliary tracts were retrogradely perfused with green fluorescent dye, fluorescein isothiocyanate (FITC). The liver was then observed under confocal microscopy. The fine-scale and three-dimensional (3D) structure of the whole biliary tree, particularly the network of the end-terminal bile canaliculi and neighboring hepatocytes were clearly visualized. The biliary tracts displayed clear distinct characteristics in normal liver and diseased liver models. Taken together, we have developed a simple and repeatable imaging method to visualize the fine-scale and hierarchical architecture of the biliary tracts spreading in the mouse liver.

Laparoscopic duodenum-preserving total pancreatic head resection using real-time indocyanine green fluorescence imaging

BACKGROUND

It is technical challenging to perform laparoscopic duodenum-preserving pancreatic head resection (LDPPHR). Only a few case reports and case series of LDPPHR are available in the literature.

MATERIALS AND METHODS

From February 2019 to November 2019, 24 cases of LDPPHR were carried out in the Department of Pancreas Surgery, West China Hospital, Sichuan University. Data were prospectively collected in terms of demographic characteristics (age, gender, BMI, and pathological diagnosis), intraoperative variables (operative time, estimated blood loss, transfusion, pancreatic texture, and diameter of main pancreatic duct), and post-operative variables (time for oral intake, post-operative hospital stay, and complications).

RESULTS

Nine male patients and fifteen female patients were included in this study. The median age of these patients was 43 years. All patients underwent duodenum-preserving total pancreatic head resection laparoscopically. The median operative time was 255 min. The median estimated blood loss was 200 ml. One patient required blood transfusion. The median post-operative hospital stay was 10 days. Three patients suffered from biliary fistula. Eleven patients (45.8%) suffered from pancreatic fistula; however, only one patient (4.2%) suffered from grade B pancreatic fistula. No patient suffered from grade C pancreatic fistula. One patient with chronic pancreatitis required re-operation for jejunal anastomotic bleeding on the first post-operative day. No patient suffered from gastroparesis, duodenal necrosis, or abdominal bleeding. The 30-day mortality was 0.

CONCLUSION

LDPPHR is safe and feasible. Real-time indocyanine green fluorescence imaging may help prevent bile duct injury and bile leakage.

Extrahepatic cholangiography in near-infrared II window with the clinically approved fluorescence agent indocyanine green: a promising imaging technology for intraoperative diagnosis

Rationale: Biliary tract injury remains the most dreaded complication during laparoscopic cholecystectomy. New intraoperative guidance technologies, including near-infrared (NIR) fluorescence cholangiography with indocyanine green (ICG), are under comprehensive evaluation. Previous studies had shown the limitations of traditional NIR light (NIR-I, 700-900 nm) in visualizing the biliary tract structures in specific clinical situations. The aim of this study was to evaluate the feasibility of performing the extrahepatic cholangiography in the second NIR window (NIR-II, 900-1700 nm) and compare it to the conventional NIR-I imaging. Methods: The absorption and emission spectra, as well as fluorescence intensity and photostability of ICG-bile solution in the NIR-II window were recorded and measured. In vitro intralipid® phantom imaging was performed to evaluate tissue penetrating depth in NIR-I and NIR-II window. Different clinical scenarios were modeled by broadening the penetration distance or generating bile duct injuries, and bile duct visualization and lesion site diagnosis in the NIR-II window were evaluated and compared with NIR-I imaging. Results: The fluorescence spectrum of ICG-bile solution extends well into the NIR-II region, exhibiting intense emission value and excellent photostability sufficient for NIR-II biliary tract imaging. Extrahepatic cholangiography using ICG in the NIR-II window obviously reduced background signal and enhanced penetration depth, providing more structural information and improved visualization of the bile duct or lesion location in simulated clinical scenarios, outperforming the NIR-I window imaging. Conclusions: The conventional clinically approved agent ICG is an excellent fluorophore for NIR-II bile duct imaging. Fluorescence cholangiography with ICG in the NIR-II window could provide adequate visualization of the biliary tract structures with increased resolution and penetration depth and might be a valid option to increase the safety of cholecystectomy in difficult cases.

Technical Note: Are Currently Used Measurements of Fluorescence Intensity in Near Infrared Fluorescence Imaging During Laparoscopic Cholecystectomy Comparable?

Aims: To investigate whether different calculation methods to express fluorescence intensity (FI) as target-to-background (BG) ratio are comparable and which method(s) match with human perception. Materials and Methods: Comparison of three calculation methods from current literature (OsiriX^®, ImageJ^®, and Photoshop^®) to objectify FI during laparoscopic cholecystectomy measured at the exact same locations within recorded images of two categories: ex vivo and in vivo. Currently applied formulas to present FI in relation to the BG signal are compared with the subjective assessment by the human observers. These three formulas are Signal contrast = (FI in fluorescence regions-FI in BG)/255; Target-to-background ratio = (FI of target-FI of BG)/FI of BG; Signal-to-background ratio = FI of cystic duct/FI of liver and Target-to-background ratio = (FI of target-noise)/(FI of BG-noise). Results: In our evaluation OsiriX and ImageJ provided similar results, whereas OsiriX values were structurally slightly lower compared with ImageJ. Values obtained through Photoshop were less evidently related to those obtained with OsiriX and ImageJ. The formula Target-to-background ratio = (FI of target-noise)/(FI of BG-noise) was less corresponding with human perception compared with the other used formulas. Conclusions: FI results based on measurements using the programs OsiriX and ImageJ are similar, allowing for comparison of results between these programs. Results using Photoshop differ significantly, making direct comparison impossible. This is an important finding when interpreting study results. We propose to report both target and BG FI in articles, so that proper interpretation between articles can be made.

The role of indocyanine green fluoroscopy for intraoperative bile duct visualization during laparoscopic cholecystectomy: an observational cohort study in 70 patients

Background

Bile duct injury is the most feared complication during laparoscopic cholecystectomy. Real-time intraoperative imaging using indocyanine green (ICG) might reduce the risk of bile duct injury by improving visualization of the biliary tree during laparoscopic cholecystectomy. We compared the outcomes of laparoscopic cholecystectomy in patients with and without real-time ICG.

Methods

A retrospective analysis of the data of patients undergoing laparoscopic cholecystectomy with and without ICG in a referral centre for minimally invasive surgery was performed. We hypothesized that laparoscopic cholecystectomy with real-time ICG enables a better identification of the biliary tree and thus increases surgical safety. The outcomes of laparoscopic cholecystectomy with and without ICG were compared using the duration of surgery, the rate of bile duct injury, the rate of conversion, complications and the length of stay.

Results

Seventy patients including 29 with and 41 without ICG underwent laparoscopic cholecystectomy within the period of investigation. The median duration of surgery was 53.0 vs. 54.0 min while the median length of stay was 2.0 d in the group with and without ICG respectively. The rate of conversion was 2.4% in the group without ICG, while no conversion was performed in the group with ICG. NO bile duct injury occurred in both groups. These differences were not statistically significant.

Conclusion

Laparoscopic cholecystectomy with real-time indocyanine green fluorescence cholangiography enables a better visualization and identification of biliary tree and therefore should be considered as a means of increasing the safety of laparoscopic cholecystectomy.

Intraoperative Parathyroid Localization with Near-Infrared Fluorescence Imaging Using Indocyanine Green during Total Parathyroidectomy for Secondary Hyperparathyroidism

The detection of all glands during total parathyroidectomy (TPTX) in secondary hyperparathyroidism (SHPT) patients is often difficult due to their variability in number and location. The objective of this study was to evaluate the feasibility of near-infrared fluorescence (NIRF) imaging using indocyanine green (ICG) for intraoperative parathyroid gland (PTG) localization in SHPT patients. Twenty-nine patients with SHPT were divided into two groups with or without intraoperative NIRF imaging. ICG was administered in patients undergoing intraoperative imaging, and the fluorescence of PTGs was assessed. Clinical and histopathologic variables were analyzed to determine factors associated with ICG uptake. Comparisons between NIRF and preoperative imaging, as well as differences between groups with or without NIRF imaging, were carried out to evaluate the efficacy of this technique. Most PTGs could be clearly identified, including one ectopic gland. The sensitivity of NIRF imaging is 91.1% in contrast to 81.82% for ultrasonography (US), 62.34% for ^99mTc-MIBI and 85.71% for computed tomography (CT). In addition, intraoperative NIRF imaging can reduce the operation time and improve the complete resection rate compared with the group not using it. Intraoperative NIRF imaging using ICG during TPTX is technically feasible and reliable for assisting surgeons in detecting and confirming PTGs.