Optimization of near-infrared fluorescence cholangiography for open and laparoscopic surgery

Determining the patency of biliary tracts in dogs with gallbladder mucocele using near-infrared cholangiography with indocyanine green

Cholecystectomy is indicated for gallbladder mucoceles (GBM). Evaluating the patency of the biliary duct and precise biliary tree visualization is crucial for reducing the risk of compromised bile flow after surgery. Therefore, intraoperative cholangiography (IOC) is recommended during cholecystectomy to prevent biliary tract injury. Although indocyanine green (ICG) cholangiography has been extensively reported in human medicine, only one study has been conducted in veterinary medicine. Therefore, this study aimed to demonstrate the use of ICG for IOC to identify fluorescent biliary tract images and determine the patency of the common bile duct during cholecystectomy in dogs. This study comprised 27 dogs, consisting of 17 with gallbladder mucoceles (GBM) and 10 controls, specifically including dogs that had undergone elective cholecystectomy for GBM. ICG injection (0.25 mg/kg) was administered intravenously at least 45 minutes before surgery. During the operation, fluorescent images from cholangiography were displayed on the monitor and obtained in black-and-white mode for the comparison of fluorescence intensity (FI). The FI values of the gallbladders (GBs) and common bile duct (CBD) were measured using FI analyzing software (MGViewer V1.1.1, MetapleBio Inc.). The results demonstrated successful CBD patency identification in all cases. Mobile GBM showed partial gallbladder visibility, whereas immobile GBM showed limited visibility. Additionally, insights into the adequate visualization of the remaining extrahepatic biliary tree anatomy were provided, extending beyond the assessment of CBD patency and gallbladder intensity. Our study demonstrates the potential of fluorescent IOC using intravenous injection of ICG for assessing the patency of the cystic duct and common bile duct during cholecystectomy in patients with GBM, eliminating the need for surgical catheterization and flushing of the biliary ducts. Further research is warranted to investigate and validate the broader applicability of ICG cholangiography in veterinary medicine.

Enhancing biliary structure identification using percutaneous cholecystostomy drain delivery of indocyanine green: a glowing two case review

The use of indocyanine green for fluorescent cholangiography in patients with cholecystitis initially treated with percutaneous cholecystostomy drainage catheters was described in this two case series. Two patients underwent robotic assisted cholecystectomy with fluorescent cholangiography and indocyanine green through percutaneous cholecystostomy drainage catheters. The patients were diagnosed with acute cholecystitis. Directed injection of indocyanine green allowed for direct visualization of the biliary system allowing for a safe identification of the critical view of safety. Injection of indocyanine green for fluorescent cholangiography through percutaneous cholecystostomy drainage catheters is reliable to assess the critical view of safety and allows for improved identification of the biliary tree anatomy. Administration of indocyanine green through the percutaneous cholecystostomy drainage catheters avoided background hepatic fluorescence and increased contrast between biliary structures.

Near-infrared fluorescence cholangiography in dogs: A pilot study

OBJECTIVE

To determine the effect of indocyanine green (ICG) dose and timing of administration on near-infrared fluorescence (NIRF) imaging of the normal canine biliary tree.

STUDY DESIGN

Preclinical prospective study.

ANIMALS

Eight purpose-bred beagles.

METHODS

The dogs were randomized to receive two of four intravenous ICG dose (low [L]:0.05 mg/kg or high [H]:0.25 mg/kg)/time (0 and 3 h prior to NIRF) combinations. NIRF images were collected every 10 min for 120 min. Target (cystic duct)-to-background (liver) ratios were calculated for all timepoints and compared.

RESULTS

ICG cholangiography was successful in all dogs. The contrast ratio was above 1 in the L0 group by 20 min and reached its peak at 100 min. In the H0 group, the ratio was above 1 by 60 min and reached its peak at 90 min. Contrast ratios above 2 (fluorescence twice as bright in the cystic duct compared to the liver) were maintained from 180 to 300 min for L3 and H3 and was achieved after 80 min for L0.

CONCLUSION

Low dose ICG provided better ratios early after injection compared to the high dose which remained highly concentrated in the liver tissue after injection. Both doses provided excellent visualization of the biliary tree at 3 h post injection, low dose ICG provided better ratios from 3 to 5 h post injection. Based on these results, 0.05 mg/kg of ICG administered at anesthetic premedication, or as early as 3 h prior to laparoscopic surgery should yield optimal fluorescence images.

CLINICAL SIGNIFICANCE

This study provides guidelines for NIRF cholangiography in clinically normal dogs.

Near-infrared cholangiography with intragallbladder indocyanine green injection in minimally invasive cholecystectomy

Laparoscopic cholecystectomy (LC) remains one of the most commonly performed procedures in adult and paediatric populations. Despite the advances made in intraoperative biliary anatomy recognition, iatrogenic bile duct injuries during LC represent a fatal complication and consist an economic burden for healthcare systems. A series of methods have been proposed to prevent bile duct injury, among them the use of indocyanine green (ICG) fluorescence. The most commonly reported method of ICG injection is the intravenous administration, while literature is lacking studies investigating the direct intragallbladder ICG injection. This narrative mini-review aims to assess the potential applications, usefulness, and limitations of intragallbladder ICG fluorescence in LC. Authors screened the available international literature to identify the reports of intragallbladder ICG fluorescence imaging in minimally invasive cholecystectomy, as well as special issues regarding its use. Literature search retrieved four prospective cohort studies, three case-control studies, and one case report. In the three case-control studies selected, intragallbladder near-infrared cholangiography (NIRC) was compared with standard LC under white light, with intravenous administration of ICG for NIRC and with standard intraoperative cholangiography (IOC). In total, 133 patients reported in the literature have been administered intragallbladder ICG administration for biliary mapping during LC. Literature includes several reports of intragallbladder ICG administration, but a standardized technique has not been established yet. Published data suggest that NIRC with intragallbladder ICG injection is a promising method to achieve biliary mapping, overwhelming limitations of IOC including intervention and radiation exposure, as well as the high hepatic parenchyma signal and time interval needed in intravenous ICG fluorescence. Evidence-based guidelines on the role of intragallbladder ICG fluorescence in LC require the assessment of further studies and multicenter data collection into large registries.

Indocyanine green (ICG) fluorescence-enhanced applications in pediatric surgery

The breadth of pediatric surgical practice and variety of anatomic anomalies that characterize surgical disease in children and neonates require a unique level of operative mastery and versatility. Intraoperative navigation of small, complex, and often abnormal anatomy presents a particular challenge for pediatric surgeons. Clinical experience with fluorescent tissue dye, specifically indocyanine green (ICG), is quickly gaining widespread incorporation into adult surgical practice as a safe, non-toxic means of accurately visualizing tissue perfusion, lymphatic flow, and biliary anatomy to enhance operative speed, safety, and patient outcomes. Experience in pediatric surgery, however, remains limited. ICG-fluorescence guided surgery is poised to address the challenges of pediatric and neonatal operations for a growing breadth of surgical pathology. Fluorescent angiography has permitted intraoperative visualization of colorectal flap perfusion for complex pelvic reconstruction and anastomotic perfusion after esophageal atresia repair, while its hepatic absorption and biliary excretion has made it an excellent agent for delineating the dissection plane in the Kasai portoenterostomy and identifying both primary and metastatic hepatoblastoma lesions. Subcutaneous and intra-lymphatic ICG injection can identify iatrogenic chylous leaks and improved yields in sentinel lymph node biopsies. ICG-guided surgery holds promise for more widespread use in pediatric surgical conditions, and continued evaluation of efficacy will be necessary to better inform clinical practice and identify where to focus and develop this technical resource.

Biliary Anatomy Visualization and Surgeon Satisfaction Using Standard Cholangiography versus Indocyanine Green Fluorescent Cholangiography during Elective Laparoscopic Cholecystectomy: A Randomized Controlled Trial

Background: Intraoperative biliary anatomy recognition is crucial for safety during laparoscopic cholecystectomy, since iatrogenic bile duct injuries represent a fatal complication, occurring in up to 0.9% of patients. Indocyanine green fluorescence cholangiography (ICG-FC) is a safe and cost-effective procedure for achieving a critical view of safety and recognizing early biliary injuries. The aim of this study is to compare the perioperative outcomes, usefulness and safety of standard intraoperative cholangiography (IOC) with ICG-FC with intravenous ICG. Methods: Between 1 June 2021 and 31 December 2022, 160 patients undergoing elective LC were randomized into two equal groups: Group A (standard IOC) and group B (ICG-FC with intravenous ICG). Results: No significant difference was found between the two groups regarding demographics, surgery indication or surgery duration. No significant difference was found regarding the visualization of critical biliary structures. However, the surgeon satisfaction and cholangiography duration presented significant differences in favor of ICG-FC. Regarding the inflammatory response, a significant difference between the two groups was found only in postoperative WBC levels. Hepatic and renal function test results were not significantly different between the two groups on the first postoperative day, except for direct bilirubin. No statistically significant difference was noted regarding 30-day postoperative complications, while none of the complications noted included bile duct injury events. Conclusions: ICG-FC presents equivalent results to IOC regarding extrahepatic biliary visualization and postoperative complications. However, more studies need to be performed in order to standardize the optimal dose, timing and mode of administration.

Fluorescence cholangiography for laparoscopic cholecystectomy: how, when, and why? A single-center preliminary study

INTRODUCTION

Bile duct injuries avoidance is a key goal of biliary surgery. In this prospective study we evaluate the safety and feasibility of ICG fluorescent cholangiography during laparoscopic cholecystectomy (LC) focusing on the optimization of timing and dose administration.

MATERIAL AND METHODS

From February to December 2022 fifty-four LC were performed with fluorescence imaging in our surgical department. 2.5 mg ICG were administered intravenously between 5 h and 24 h before surgery. Near-infrared fluorescent cholangiography (NIRF-C) was performed. Adequate fluorescence was evaluated by comparing agent accumulation in the gallbladder and the extrahepatic duct and the background of liver parenchyma.

RESULTS

Biliary anatomy was identified in all cases. Median time of ICG administration was 11 h previous surgery and three groups of patients were identified: group A receiving ICG 5-9 h, group B 10-14 h, group C 15-24 h before surgery. Peak contrast was gained in group B, with minimal fluorescence of liver parenchyma and more intense visibility of the biliary tract. Intraoperative cholangiogram was unnecessary in all cases.

CONCLUSION

Fluorescent cholangiography during LC is safe and feasible overcoming the limits of other techniques available. 2.5 mg ICG administered 10-14 h before surgery produces optimal outcomes for near-infrared (NIR) fluorescent cholangiography.

Investigation of the optimal indocyanine green dose in real-time fluorescent cholangiography during laparoscopic cholecystectomy with an ultra-high-definition 4K fluorescent system: a randomized controlled trial

This study aimed to investigate the indocyanine green (ICG) dose in real-time fluorescent cholangiography during laparoscopic cholecystectomy (LC) with a 4K fluorescent system. A randomized controlled clinical trial was conducted in patients who underwent LC for treatment of cholelithiasis. Using the OptoMedic 4K fluorescent endoscopic system, we compared four different doses of ICG (1, 10, 25, and 100 µg) administered intravenously within 30 min preoperatively and evaluated the fluorescence intensity (FI) of the common bile duct and liver background and the bile-to-liver ratio (BLR) of the FI at three timepoints: before surgical dissection of the cystohepatic triangle, before clipping the cystic duct, and before closure. Forty patients were randomized into four groups, and 33 patients were fully analyzed, with 10 patients in Group A (1 µg), 7 patients in Group B (10 µg), 9 patients in Group C (25 µg), and 7 patients in Group D (100 µg). The preoperative baseline characteristics were compared among groups (p > 0.05). Group A showed no or minimal FI in the bile duct and liver background, while Group D showed extremely high FIs in the bile duct and in the liver background at the three timepoints. Groups B and C presented with visible FI in the bile duct and low FI in the liver background. With increasing ICG doses, the FIs in the liver background and bile duct gradually increased at the three timepoints. The BLR, however, showed no increasing trend with an increasing ICG dose. A relatively high BLR on average was found in Group B, without a significant difference compared to the other groups (p > 0.05). An ICG dose ranging from 10 to 25 µg by intravenous administration within 30 min preoperatively was appropriate for real-time fluorescent cholangiography in LC with a 4K fluorescent system. Registration: This study was registered in the Chinese Clinical Trial Registry (ChiCTR No: ChiCTR2200064726).

Identification of the ideal weight-based indocyanine green dose for fluorescent cholangiography

BACKGROUND

Ideal visualization of fluorescent cholangiography during laparoscopic cholecystectomy is when maximum fluorescence into biliary ducts and absent signal into liver parenchyma, defined as "signal to background ratio" (SBR), is obtained. Such condition is mainly dependent by indocyanine green (ICG) dose and timing. The aim of this study was to identify the ideal ICG dose to obtain the best possible intraoperative visualization of the extra-hepatic biliary tree.

METHODS

The first part of the study was used to define a range of small weight-based ICG dosages using the mathematical function bisection method. During the second part of the study, the midpoint dose of the identified range, was tested in 50 consecutive cholecystectomies using a laser-based fluorescence laparoscopic camera (SynergyID system by Arthrex, Naples, FL, USA). Timing administration was set at 1 h before surgery, since this is the most common situation in clinical practice. Fluorescence intensity of bile ducts and liver parenchyma were assessed both subjectively, by blinded operative surgeon, as well as objectively, using an image analysis software (Fiji plugin), before and after Calot's triangle dissection.

RESULTS

Fourteen patients were included in the first part of the study and ICG dose between 0.01191406 and 0.0119873 mg/kg was identified. The second part confirmed previous results after testing the dosage equal to 0.0119 mg/kg (midpoint of the defined range) in 50 consecutive cholecystectomies. Cystic duct was identified in 66 and 100% of cases before and after dissection of Calot's triangle respectively. On the other hand, common bile duct was identified in 82 and 92% before and after dissection respectively. Subjective and objective SBRs confirmed the benefit of the identified ICG dose.

CONCLUSION

ICG dose calculated by 0.0119 mg/kg administered one hour before surgery allows an ideal intraoperative visualization of the extra-hepatic biliary tree.

REGISTRATION NUMBER

ISRCTN10190039.

Preclinical evaluation of molecularly targeted fluorescent probes in perfused amputated human limbs

SIGNIFICANCE

This first-in-kind, perfused, and amputated human limb model allows for the collection of human data in preclinical selection of lead fluorescent agents. The model facilitates more accurate selection and testing of fluorophores with human-specific physiology, such as differential uptake and signal in fat between animal and human models with zero risk to human patients. Preclinical testing using this approach may also allow for the determination of tissue toxicity, clearance time of fluorophores, and the production of harmful metabolites.

AIM

This study was conducted to determine the fluorescence intensity values and tissue specificity of a preclinical, nerve tissue targeted fluorophore, as well as the capacity of this first-in-kind model to be used for lead fluorescent agent selection in the future.

APPROACH

Freshly amputated human limbs were perfused for 30 min prior to in situ and ex vivo imaging of nerves with both open-field and closed-field commercial fluorescence imaging systems.

RESULTS

In situ, open-field imaging demonstrated a signal-to-background ratio (SBR) of 4.7 when comparing the nerve with adjacent muscle tissue. Closed-field imaging demonstrated an SBR of 3.8 when the nerve was compared with adipose tissue and 4.8 when the nerve was compared with muscle.

CONCLUSIONS

This model demonstrates an opportunity for preclinical testing, evaluation, and selection of fluorophores for use in clinical trials as well as an opportunity to study peripheral pathologies in a controlled environment.

Laboratory scoring system to predict hepatic indocyanine green clearance ability during fluorescence imaging-guided laparoscopic hepatectomy

BACKGROUND

Indocyanine green (ICG) fluorescence played an important role in tumor localization and margin delineation in hepatobiliary surgery. However, the preoperative regimen of ICG administration was still controversial. Factors associated with tumor fluorescence staining effect were unclear.

AIM

To investigate the preoperative laboratory indexes corelated with ICG fluorescence staining effect and establish a novel laboratory scoring system to screen specifical patients who need ICG dose adjustment.

METHODS

To investigate the predictive indicators of ICG fluorescence characteristics in patients undergoing laparoscopic hepatectomy from January 2018 to January 2021 were included. Blood laboratory tests were completed within 1 wk before surgery. All patients received 5 mg ICG injection 24 h before surgery for preliminary tumor imaging. ImageJ software was used to measure the fluorescence intensity values of regions of interest. Correlation analysis was used to identify risk factors. A laboratory risk model was established to identify individuals at high risk for high liver background fluorescence.

RESULTS

There were 110 patients who were enrolled in this study from January 2019 to January 2021. The mean values of fluorescence intensity of liver background (FI-LB), fluorescence intensity of gallbladder, and fluorescence intensity of target area were 18.87 ± 17.06, 54.84 ± 33.29, and 68.56 ± 36.11, respectively. The receiver operating characteristic (ROC) curve showed that FI-LB was a good indicator for liver clearance ability [area under the ROC curve (AUC) = 0.984]. Correlation analysis found pre-operative aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transpeptidase, adenosine deaminase, and lactate dehydrogenase were positively associated with FI-LB and red blood cell, cholinesterase, and were negatively associated with FI-LB. Total laboratory risk score (TLRS) was calculated according to ROC curve (AUC = 0.848, sensitivity = 0.773, specificity = 0.885). When TLRS was greater than 6.5, the liver clearance ability of ICG was considered as poor.

CONCLUSION

Preoperative laboratory blood indicators can predict hepatic ICG clearance ability. Surgeons can adjust the dose and timing of ICG preoperatively to achieve better liver fluorescent staining.

Application of indocyanine green in surgery: A review of current evidence and implementation in trauma patients

Background: Modern surgical medicine strives to manage trauma while improving outcomes using functional imaging. Identification of viable tissues is crucial for the surgical management of polytrauma and burn patients presenting with soft tissue and hollow viscus injuries. Bowel anastomosis after trauma-related resection is associated with a high rate of leakage. The ability of the surgeon’s bare eye to determine bowel viability remains limited, and the need for a more standardized objective assessment has not yet been fulfilled. Hence, there is a need for more precise diagnostic tools to enhance surgical evaluation and visualization to aid early diagnosis and timely management to minimize trauma-associated complications. Indocyanine green (ICG) coupled with fluorescence angiography is a potential solution for this problem. ICG is a fluorescent dye that responds to near-infrared irradiation. Methods: We conducted a narrative review to address the utility of ICG in the surgical management of patients with trauma as well as elective surgery. Discussion: ICG has many applications in different medical fields and has recently become an important clinical indicator for surgical guidance. However, there is a paucity of information regarding the use of this technology to treat traumas. Recently, angiography with ICG has been introduced in clinical practice to visualize and quantify organ perfusion under several conditions, leading to fewer cases of anastomotic insufficiency. This has great potential to bridge this gap and enhance the clinical outcomes of surgery and patient safety. However, there is no consensus on the ideal dose, time, and manner of administration nor the indications that ICG provides a genuine advantage through greater safety in trauma surgical settings. Conclusions: There is a scarcity of publications describing the use of ICG in trauma patients as a potentially useful strategy to facilitate intraoperative decisions and to limit the extent of surgical resection. This review will improve our understanding of the utility of intraoperative ICG fluorescence in guiding and assisting trauma surgeons to deal with the intraoperative challenges and thus improve the patients’ operative care and safety in the field of trauma surgery.

Real-time Indocyanine Green Fluorescence Technique Reduces Anastomotic Leakage in Bilioenteric Anastomosis: A Case Report and literature review

BACKGROUND

Anastomotic leakage is a serious complication that can occur in bilioenteric anastomosis surgery, leading to significant morbidity and mortality. Currently, practitioners rely on subjective measures to determine anastomotic perfusion and mechanical integrity, which have limitations. The use of indocyanine green fluorescence technology has become increasingly widespread in clinical practice, especially in gastrointestinal-related surgery. This technique has a unique role in evaluating the blood perfusion of anastomoses and reducing the incidence of anastomotic leakage. However, there have been no reports of its use in bilioenteric anastomosis surgery. Further research is needed to investigate the potential benefits of indocyanine green fluorescence technology in improving outcomes and reducing complications in this type of surgery.

CASE SUMMARY

a 50-year-old female patient underwent total laparoscopic radical resection of cholangiocarcinoma. During the surgery, indocyanine green fluorescence technology was used to complete the biliary intestinal anastomosis under full visual and dynamic monitoring. The patient recovered well after the operation without experiencing biliary leakage or other complications.

CONCLUSION

The present case study underscores the potential advantages associated with the incorporation of intraoperative real-time indocyanine green (ICG) technology in bilioenteric anastomosis surgery. By facilitating enhanced visualization and assessment of anastomotic perfusion and mechanical stability, this state-of-the-art technique may help mitigate the occurrence of anastomotic leaks while simultaneously improving patient outcomes. Notably, intravenous administration of ICG at a dose of 2.5 mg/kg, administered 24 hours prior to surgery, has been found to yield optimal visualization outcomes.

Fluorescence-guided surgery: comprehensive review

BACKGROUND

Despite significant improvements in preoperative workup and surgical planning, surgeons often rely on their eyes and hands during surgery. Although this can be sufficient in some patients, intraoperative guidance is highly desirable. Near-infrared fluorescence has been advocated as a potential technique to guide surgeons during surgery.

METHODS

A literature search was conducted to identify relevant articles for fluorescence-guided surgery. The literature search was performed using Medical Subject Headings on PubMed for articles in English until November 2022 and a narrative review undertaken.

RESULTS

The use of invisible light, enabling real-time imaging, superior penetration depth, and the possibility to use targeted imaging agents, makes this optical imaging technique increasingly popular. Four main indications are described in this review: tissue perfusion, lymph node assessment, anatomy of vital structures, and tumour tissue imaging. Furthermore, this review provides an overview of future opportunities in the field of fluorescence-guided surgery.

CONCLUSION

Fluorescence-guided surgery has proven to be a widely innovative technique applicable in many fields of surgery. The potential indications for its use are diverse and can be combined. The big challenge for the future will be in bringing experimental fluorophores and conjugates through trials and into clinical practice, as well as validation of computer visualization with large data sets. This will require collaborative surgical groups focusing on utility, efficacy, and outcomes for these techniques.

Detection of the communicating accessory bile duct in laparoscopic resection of residual gallbladder by the combination of the indocyanine green fluorescence cholangiography and the intraoperative cholangiography: A case report

BACKGROUND

The partial cholecystectomy may be performed while in complicated laparoscopic cholecystectomy (LC). Biliary anomalies especially the accessory bile duct are established high risk of bile duct injury (BDI) in LC. Laparoscopic resection of residual gallbladder is a challenging procedure and extremely vulnerable to BDI. We report the execution of a laparoscopic resection of residual gallbladder with a communicating accessory bile duct using indocyanine green (ICG) fluorescence cholangiography and the intraoperative cholangiography (IOC). A case that has not been reported previously.

PRESENTATION OF CASE

A 29-year-old female with history of laparoscopic partial cholecystectomy was admitted in our hospital. Magnetic resonance cholangiopancreatography (MRCP) revealed the residual gallbladder with an accessory bile duct. Considering the complexity of this patient, we performed a laparoscopic surgery using ICG fluorescence cholangiography. ICG was injected intravenously 1h before the surgery, the residual gallbladder and the extrahepatic biliary structures including the accessory bile duct were imaged in green in fluorescence imaging that could be recognized clearly. IOC revealed that residual gallbladder communicated with intrahepatic bile duct through the accessory bile duct and drained into the common bile duct (CBD). The entire procedure was performed smoothly and successfully without bile duct injuries.

DISCUSSION

Laparoscopic resection of residual gallbladder is a challenging procedure. Fluorescence cholangiography using ICG is regarded as a novel technique that could provide a real-time imaging intraoperative, which allowed to recognize and identify the residual gallbladder and the extrahepatic bile duct. IOC is also important in identifying a communicating accessory bile duct. Under the guidance of them, we completed this laparoscopic surgery.

CONCLUSIONS

The combination of fluorescence cholangiography using ICG and IOC have profound significance in complicated LC.

Dose and administration time of indocyanine green in near-infrared fluorescence cholangiography during laparoscopic cholecystectomy (DOTIG): study protocol for a randomised clinical trial

BACKGROUND

One of the most severe complications in laparoscopic cholecystectomy (LC) is intraoperative bile duct injury (BDI). Despite its low incidence, the medical implications for the patient can be serious. Besides, BDI can also generate significant legal issues in healthcare. Different techniques have been described to reduce the incidence of this complication, and near-infrared fluorescence cholangiography with indocyanine green (NIRFC-ICG) is one of the latest additions. In spite of the great interest aroused by this procedure, there are currently great disparities in the usage or administration protocols of ICG.

METHODS AND ANALYSIS

This is a randomised, multicentre, per-protocol analysis, open clinical trial with four arms. The estimated duration of the trial is 12 months. The aim of the study is to analyse whether there are differences between the dose and administration ICG intervals to obtain good-quality NIRFC during LC. The primary outcome is the degree of identification of critical biliary structures during LC. In addition, different factors will be analysed that may have an influence on the results of this technique.

ETHICS AND DISSEMINATION

The trial will be conducted according to the recommendations for Clinical Trials in the Declaration of Helsinki Ethical Principles for Medical Research Involving Human Subjects and the recommendations of the Spanish Agency of Medicines and Medical Devices (AEMPs) for clinical trials. This trial was approved by the local institutional Ethics Committee and the AEMPs. The results of the study will be presented to the scientific community through publications, conferences or other means.

EUDRACT NUMBER

2022-000904-36.

PROTOCOL VERSION

V.1.4, 2 June 2022 TRIAL REGISTRATION NUMBER: NCT05419947.

Laparoscopic fluorescence imaging technique for visualizing biliary structures using sodium fluorescein: the result of a preclinical study in a porcine model

Purpose

Near-infrared fluorescence imaging has been recently applied in the field of hepatobiliary surgery. Our objective was to apply blue-light fluorescence cholangiography during laparoscopic surgery. Therefore, we designed a preclinical study to evaluate the feasibility of using blue-light fluorescence for cholangiography in a porcine model.

Methods

Five millimeters of sodium fluorescein (SF) solution was administered into the gallbladder of 20 male 3-way crossbred (Landrace × Yorkshire × Duroc) pigs in laparoscopic approach. The biliary tree was observed under blue light (a peak wavelength of 450 nm) emitted from a commercialized light-emitting diode (LED) light source (XLS1 extreme, Chammed).

Results

In 18 of 20 porcine models, immediately after SF solution was administered into the gallbladder, it was possible to visualize the biliary tree under blue light emitted from the LED light source.

Conclusion

This study provided a preclinical basis for using blue-light fluorescence cholangiography using SF in laparoscopic surgery. The clinical feasibility of blue-light fluorescence imaging techniques for laparoscopic cholecystectomy remained to be demonstrated.

Real-time fluorescent cholangiography with indocyanine green in laparoscopic cholecystectomy: a randomized controlled trial to establish the optimal indocyanine green dose within 30 min preoperatively

PURPOSE

To establish the optimal dose of indocyanine green (ICG) to administer intravenously 30 min before laparoscopic cholecystectomy (LC).

METHODS

In this randomized controlled trial (RCT), patients undergoing LC for cholecystitis, cholelithiasis, and/or cholecystic polyps were randomized into four groups given four different ICG doses (0.025, 0.1, 0.25, 2.5 mg). Using OptoMedic endoscopy combined with a near-infrared fluorescent imaging system, we evaluated the fluorescence intensity (FI) of the common bile duct and liver at three timepoints: before surgical dissection of the cystohepatic triangle, before clipping of the cystic duct, and before closure. The bile duct-to-liver ratio (BLR) of the FI was analyzed to assess the cholangiography effect.

RESULTS

Sixty-four patients were allocated to one of four groups, with 40 patients included in the final analysis. Generally, with increasing ICG doses, the levels of FI in the bile duct and liver increased gradually at each of the three timepoints. Before surgical dissection of the cystohepatic triangle, 0.1-mg ICG showed the highest BLR (F = 3.47, p = 0.0259). Before clipping the cystic duct and before closure, the 0.025- and 0.1-mg groups showed a higher BLR than the 0.25- and 2.5-mg groups (p < 0.05). When setting the ideal cholangiography at a BLR ≥ 1, ≥ 3, or ≥ 5, the 0.1-mg group showed the highest qualified case number at the three timepoints.

CONCLUSIONS

The intravenous administration of 0.1-mg ICG, 30 min before LC, is significantly better for fluorescent cholangiography of the extrahepatic biliary structures before dissection and clipping of the cystohepatic triangle.

TRIAL REGISTRATION

This study was registered in the Chinese Clinical Trial Registry (ChiCTR) (ChiCTR2200057933).

Preliminary exploration of the efficacy of laparoscopic fluorescence cholangiography (LFC) in the diagnosis of biliary atresia compared with intraoperative cholangiography (IOC)

BACKGROUND

Intraoperative cholangiography (IOC) has been the gold standard for diagnosing biliary atresia (BA). Our study attempted to diagnose BA using laparoscopic fluorescein cholangiography (LFC).

METHODS

We retrospectively included 18 patients with preoperative suspected BA as the case group and 4 without extrahepatic biliary obstruction requiring laparoscopic surgery as the control group. All patients received indocyanine green (ICG) intravenously at 0.05 mg/Kg. The first 6 patients in the case group underwent IOC and LFC simultaneously, and the control group completed LFC. The imaging characteristics of LFC were recorded and summarized by the conventional and fluorescence mode of the endoscopic fluorescence imaging system (DPM-ENDOCAM-03). On this basis, 12 patients in the case group were diagnosed as BA according to LFC without IOC, and all 18 patients completed open Kasai surgery to confirm the diagnosis.

RESULTS

Laparoscopic fluorescence mode in BA detected liver fluorescence but no visualization of the extrahepatic bile ducts. However, the extrahepatic bile ducts in the control group were visible. Based on the imaging characteristics summarized from the LFC of the first 6 cases with BA in the case group, the remaining 12 cases who only underwent LFC were also successfully diagnosed with BA. Furthermore, the formation of hepatic hilar fibrous mass was found in all the patients during the open Kasai procedure, which confirmed the BA diagnosis.

CONCLUSIONS

LFC appears as a specific pattern in BA and may be used for intraoperative diagnosis of BA. It has the advantages of simplicity, short time-consuming, and no radiation damage.

Single Camera-Based Dual-Channel Near-Infrared Fluorescence Imaging system

In this study, we propose a single camera-based dual-channel near-infrared (NIR) fluorescence imaging system that produces color and dual-channel NIR fluorescence images in real time. To simultaneously acquire color and dual-channel NIR fluorescence images of two fluorescent agents, three cameras and additional optical parts are generally used. As a result, the volume of the image acquisition unit increases, interfering with movements during surgical procedures and increasing production costs. In the system herein proposed, instead of using three cameras, we set a single camera equipped with two image sensors that can simultaneously acquire color and single-channel NIR fluorescence images, thus reducing the volume of the image acquisition unit. The single-channel NIR fluorescence images were time-divided into two channels by synchronizing the camera and two excitation lasers, and the noise caused by the crosstalk effect between the two fluorescent agents was removed through image processing. To evaluate the performance of the system, experiments were conducted for the two fluorescent agents to measure the sensitivity, crosstalk effect, and signal-to-background ratio. The compactness of the resulting image acquisition unit alleviates the inconvenient movement obstruction of previous devices during clinical and animal surgery and reduces the complexity and costs of the manufacturing process, which may facilitate the dissemination of this type of system.

Near-infrared fluorescence cholangiography at a very low dose of indocyanine green: quantification of fluorescence intensity using a colour analysis software based on the RGB color model

BACKGROUND

Indocyanine green (ICG) near-infrared fluorescence cholangiography (NIRF-C) is widely used to visualize the biliary tract during laparoscopic cholecystectomy (LC). However, the ICG dose and its dosing time vary in the literature so there is not a standard ICG protocol. The objectives of this descriptive prospective study were to demonstrate that NIRF-C at a very low dose of ICG provides good visualization of the extrahepatic biliary tree while avoiding hepatic hyperluminescence and to assess the surgeon-perceived benefit. Furthermore, another additional aim was quantifying the amount of ICG dye in the liver tissue and biliary tract through a green colour intensity (GCI) analysis according to red green blue (RGB) color model and correlating it to surgeon-perceived benefit.

METHOD

Forty-four patients were scheduled for LC. We recorded demographics, surgical indication, intraoperative details, adverse reactions to ICG, hepatic hyperluminescence, visualization of the cystic duct (CD), the common bile duct (CBD) and the cystic duct-bile duct junction (CDBDJ) before and after dissection of Calot's triangle, operation time, surgical complications and subjective surgeon data. For all procedures, a unique dose of 0.25 mg of ICG was administered intravenously during the anaesthetic induction. ICG NIRF-C was performed using the overlay mode of the VISERA ELITE II Surgical Endoscope in all surgeries. Video recordings of all 44 LC were reviewed. Using a color analysis software, the GCI of CBD versus adjacent liver tissue was calculated using RGB color model.

RESULTS

ICG NIRF-C was performed in all 44 cases. The mean operation time was 45 ± 15 min. There were no bile duct injuries (BDIs) or allergic reactions to ICG. The postoperative course was uneventful in all of cases. The mean postoperative hospital stay was 28 ± 4 h. ICG NIRF-C identified the CBD in 100% of the patients, the CD in 71% and the CDBDJ in 84%, with a surgeon satisfaction of 4/5 or 5/5 in almost 90% of surgeries based on a visual analogue scale (VAS). No statistically significant differences were found in the visualization of the biliary structures after the dissection of Calot's triangle in obese patients or with gallbladder inflammation. Furthermore, 25% of patients with a BMI ≥ 30, 27% of patients with a Nassar grade ≥ 3 and 21% of patients with gallbladder inflammation had a VAS score 5/5 compared to 6% of patients with a BMI < 30 (p = 0.215), 6% of patients with a Nassar grade < 3 (p = 0.083) and none of the patients without gallbladder inflammation (p = 0.037). Measured pixel GCI of CBD was higher than adjacent hepatic tissue for all cases regardless of the degree of gallbladder inflammation, the Nassar scale grades or the patient's BMI (p < 0.0001). In addition, a significant correlation was observed between surgeon-perceived benefit and the amount of ICG dye into the CBD according the RGB color model (p < 0.0001).

CONCLUSION

ICG NIRF-C at a very low dose of ICG (0.25 mg of ICG 20 min before surgery) enables the real-time identification of biliary ducts, thereby avoiding the hepatic hyperluminescence even in cases of obese patients or those with gallbladder inflammation.

Development of Intraoperative Near-Infrared Fluorescence Imaging System Using a Dual-CMOS Single Camera

We developed a single-camera-based near-infrared (NIR) fluorescence imaging device using indocyanine green (ICG) NIR fluorescence contrast agents for image-induced surgery. In general, a fluorescent imaging system that simultaneously provides color and NIR images uses two cameras, which is disadvantageous because it increases the imaging head of the system. Recently, a single-camera-based NIR optical imaging device with quantum efficiency partially extended to the NIR region was developed to overcome this drawback. The system used RGB_NIR filters for camera sensors to provide color and NIR images simultaneously; however, the sensitivity and resolution of the infrared images are reduced by 1/4, and the exposure time and gain cannot be set individually when acquiring color and NIR images. Thus, to overcome these shortcomings, this study developed a compact fluorescent imaging system that uses a single camera with two complementary metal-oxide semiconductor (CMOS) image sensors. Sensitivity and signal-to-background ratio were measured according to the concentrations of ICG solution, exposure time, and camera gain to evaluate the performance of the imaging system. Consequently, the clinical applicability of the system was confirmed through the toxicity analysis of the light source and in vivo testing.

Intracholecystic versus Intravenous Indocyanine Green (ICG) Injection for Biliary Anatomy Evaluation by Fluorescent Cholangiography during Laparoscopic Cholecystectomy: A Case-Control Study

(1) Background: Fluorescence cholangiography has been proposed as a method for improving the visualization and identification of extrahepatic biliary anatomy in order to possibly reduce injuries and related complications. The most common method of indocyanine green (ICG) administration is the intravenous route, whereas evidence on direct ICG injection into the gallbladder is still quite limited. We aimed to compare the two different methods of ICG administration in terms of the visualization of extrahepatic biliary anatomy during laparoscopic cholecystectomy (LC), analyzing differences in the time of visualization, as well as the efficacy, advantages, and disadvantages of both modalities. (2) Methods: A total of 35 consecutive adult patients affected by acute or chronic gallbladder disease were enrolled in this prospective case−control study. Seventeen patients underwent LC with direct gallbladder ICG injection (IC-ICG) and eighteen subjects received intravenous ICG administration (IV-ICG). (3) Results: The groups were comparable with regard to their demographic and perioperative characteristics. The IV-ICG group had a significantly shorter overall operative time compared to the IC-ICG group (p = 0.017). IV-ICG was better at delineating the duodenum and the common hepatic duct compared to the IC-ICG method (p = 0.009 and p = 0.041, respectively). The cystic duct could be delineated pre-dissection in 76.5% and 66.7% of cases in the IC-ICG and IV-ICG group, respectively, and this increased to 88.2% and 83.3% after dissection. The common bile duct could be highlighted in 76.5% and 77.8% of cases in the IC-ICG and IV-ICG group, respectively. Liver fluorescence was present in one case in the IC-ICG group and in all cases after IV-ICG administration (5.8% versus 100%; p < 0.0001). (4) Conclusions: The present study demonstrates how ICG-fluorescence cholangiography can be helpful in identifying the extrahepatic biliary anatomy during dissection of Calot’s triangle in both administration methods. In comparison with intravenous ICG injection, the intracholecystic ICG route could provide a better signal-to-background ratio by avoiding hepatic fluorescence, thus increasing the bile duct-to-liver contrast.

Routine use of ICG to enhance operative safety in emergency laparoscopic cholecystectomy: a randomized controlled trial

OBJECTIVE

To test the hypothesis that ICG fluorescence cholangiography (ICG-FC) helps to identify critical structures during laparoscopic cholecystectomy (LC) and hence reduce biliary injuries and conversions. In LC, biliary injury and conversion often happen if the biliary anatomy is misidentified.

METHODS

This was a single-center randomized controlled trial from 2017 to 2019. Patients with acute cholecystitis requiring LC were assessed for eligibility for the trial. Patients in the trial were randomized to undergo either conventional LC (conventional arm) or LC with ICG-FC (ICG arm). Conversion rate and biliary injury incidence were outcome measures.

RESULTS

Totally 92 patients participated (46 patients in each arm). The median age was 61 years in both arms (p = 0.472). The conventional arm had 22 men and 24 women; the ICG arm had 24 men and 22 women (p = 0.677). The two arms were comparable in all perioperative parameters. The time from ICG injection to surgery was 67 (16-1150) min. Both arms had an 8.7% conversion rate (p = 1.000). The median operative time was 140.5 min in the conventional arm and 149.5 min in the ICG arm (p = 0.086). The complication rate was 15.2% in the former and 10.9% in the latter (p = 0.536), and both had a 2.2% bile leakage rate. The median hospital stay was 3.5d in the former and 4.0d in the latter (p = 0.380).

CONCLUSION

ICG-FC did not make any difference in conversion or complication rate. Its routine use in LC is questionable. However, it may be helpful in difficult cholecystectomies and may be used as an adjunct.

TRIAL REGISTRATION

The trial was registered with the Institutional Review Board of University of Hong Kong/Hospital Authority Hong Kong West Cluster ( http://www.med.hku.hk/en/research/ethics-and-integrity/human-ethics ). Registration number: UW17-492.

Indocyanine Green (ICG)-Guided Identification of Hypermetabolic Pancreatic Nodules in Focal Congenital Hyperinsulinism: A Case Report in a 3-Month-Old Infant

Indocyanine green (ICG)-guided near-infrared fluorescence has been recently adopted in pediatric surgery, although its use in the treatment of congenital hyperinsulinism has not been reported. We present a case of focal congenital hyperinsulinism in which ICG-navigation with ICG was used during surgical treatment. A 3-month-old infant was referred to our institution from a peripheral hospital for episodes of persistent hypoglycemia since birth, with no response to intravenous treatment with diazoxide, octreotide, or hydrochlorothiazide. An abdominal positron emission tomography-computed tomography scan showed a hypermetabolic nodule in the proximal portion of the body of the pancreas, compatible with focal congenital hyperinsulinism. A heterozygous mutation in the ABCC gene (Ala1516Glyfs*19) frameshift type inherited from the father was identified, which supported this diagnosis. Laparoscopy-assisted surgery was performed with ICG-guided near-infrared fluorescence, with intravenous injection of 16 mg ICG (2 mg/mg), which allowed localization of the focal lesion in the body of the pancreas. The lesion was resected with bipolar electrocautery and intraoperative histological study confirmed complete resection. Plasma glucose values normalized 6 hours after surgery and the patient was discharged 5 days later. In conclusion, the use of ICG in the treatment of congenital hyperinsulinism helps to identify hypermetabolic pancreatic nodules, decreasing the likelihood of incomplete resection.

Global trends of indocyanine green fluorescence navigation in laparoscopic cholecystectomy: bibliometrics and knowledge atlas analysis

BACKGROUND

Indocyanine green fluorescence cholangiography is a new type of cholangiography that has emerged in recent years. It has many advantages, such as simplicity, safety, and efficiency, and is expected to become a routine procedure for intraoperative cholangiography in the future. However, there is no bibliometric analysis of horizontal generalization in this field. Therefore, this study aims to assess the current research status and developmental trends in this field from a global perspective and to help guide the focus of future research.

METHODS

This study was conducted by retrieving the literature related to ICG fluorescence cholangiography published in English from 2000 to 2021 from Web of Science. The Histcite. Pro tool was used to analyze the bibliometric indicators, and VOSviewer was used to visualize the research trends and hotspots in this field.

RESULTS

192 related studies were finally included. For the past 20 years, the number of related publications in this field have increased yearly, with 2010 being a breakthrough point for research in this field. Research has developed rapidly since 2013 and may continue to expand in the next several years. The USA and Japan play leading roles in this field. "SURG ENDOSC", "SURG INNOV", and "J LAPAROENDOSC ADV S" are core journals that publish high-quality literature and the latest developments in this field. Some authors who have a large number of high-quality publications include Ishizawa T and Kokudo N. The current research hotspots in this field are focused on exploring the factors that affect ICG cholangiography and optimization measures.

CONCLUSIONS

In general, the number of documents related to ICG fluorescence cholangiography is growing rapidly, with the USA and Japan being influential countries and China being one of the major producers of these documents. The optimization of this new technology will affect key developments in future research.

Intraoperative indocyanine green fluorescence cholangiography can rule out biliary atresia: A preliminary report

BACKGROUND

The prognosis of BA is known to be poor if definitive surgery is performed too late. Therefore, excluding BA as a diagnosis at an early stage is crucial. Conventional cholangiography requiring cannulation through the gallbladder may be unnecessarily invasive for patients, especially when ruling out BA. Therefore, a less invasive alternative such as indocyanine green (ICG) cholangiography, which does not require cannulation, should be established. In this study, we focused on excluding BA and confirmed the usefulness of intravenous ICG fluorescence cholangiography. To the best of our knowledge, this is the first preliminary study to report the use of intravenous ICG cholangiography for BA exclusion.

METHODS

The study participants were patients who underwent liver biopsy and intraoperative cholangiography after they were suspected to have BA, between 2013 and 2022. ICG fluorescence cholangiography was performed on all patients who provided informed consent.

RESULTS

During the study period, 88 patients underwent a laparoscopic liver biopsy and cholangiography. Among them, 65 (74%) were diagnosed with BA and underwent a subsequent laparoscopic Kasai portoenterostomy. BA was ruled out intraoperatively in 23 patients. Of the 23 patients in whom BA was ruled out, 14 underwent ICG cholangiography, 11 had gallbladder (GB) fluorescence, and 9 had both GB and common bile duct (CBD) fluorescence. Conventional cholangiography was very difficult in 2 of 23 cases: in 1 case, cannulation of the atrophic gallbladder was impossible, and cholecystectomy was indicated after multiple attempts; in 1 case, upstream cholangiography was not possible. In both cases, ICG fluorescence cholangiography successfully imaged the CBD and the GB.

CONCLUSIONS

In conclusion, intravenous ICG fluorescence cholangiography might be a useful and less invasive diagnostic procedure that can rule out BA in infants.

Fluorescence Image-Guided Navigation Surgery Using Indocyanine Green for Hepatoblastoma

In the past decade, navigation surgery using fluorescent indocyanine green (ICG) dye for hepatoblastoma (HB) has been developed for the resection of primary or metastatic tumors. Since HB cells can take up ICG but cannot excrete it to the bile duct, ICG remains in the HB cells, which can be used for navigation by fluorescent activation. The complete resection of the primary tumor as well as metastatic tumors, along with appropriate neoadjuvant and adjuvant chemotherapy, is essential for cure. ICG fluorescence can detect microscopic residual lesions in the primary lesion and identify micro-metastases in the lung or other lesions; consequently, ICG navigation surgery may improve outcomes for patients with HB. The basic technique and recent advances in ICG navigation for HB surgery are reviewed.

Efficacy of indocyanine green (ICG) fluorescent cholangiography to improve intra-operative visualization during laparoscopic cholecystectomy in pediatric patients: a comparative study between ICG-guided fluorescence and standard technique

BACKGROUND

In the last few years, indocyanine green (ICG) fluorescent cholangiography (FC) has been adopted to perform intra-operative biliary mapping during laparoscopic cholecystectomy (LC). This study aimed to compare the results of LC with and without use of ICG-FC.

METHODS

All LC operated from June 2017 to June 2021 in our unit were retrospectively reviewed. Pre-operative workup included ultrasonography to assess dilation of main biliary tree. The ICG dosage was 0.35 mg/kg and the median timing of administration was 15.5 h pre-operatively. We evaluated, analyzing videorecorded procedures, 3 parameters in both groups: the total operative time (T1), the time of cystic duct isolation, clipping and sectioning (T2), and the time of gallbladder removal from hepatic fossa (T3).

RESULTS

Forty-three LC were operated in the study period: 22 using standard technique (G1) and 21 using ICG-FC (G2). There were 27 girls and 16 boys, with median age at surgery of 11.5 years (range 7-17) and median weight of 47 kg (range 31-110). No conversions were reported in our series. In all ICG cases (except one patient under therapy with phenobarbital) the biliary tree was perfectly visualized during dissection. Intra-operative complications occurred in 3 G1 patients (13.6%): 2 bleedings from the Calot's triangle and 1 bleeding from the liver bed during the gallbladder removal. LC was significantly faster in G2 than in G1 (p = 0.001). In fact, the parameters analyzed (T1, T2, T3) were all significantly greater in G1 than in G2 (p = 0.001).

CONCLUSIONS

Based upon our experience, we strongly recommend the use of ICG-FC in all pediatric patients undergoing LC. ICG-guided fluorescence provided an excellent real-time visualization of the extrahepatic biliary tree and allowed faster and safer dissection, minimizing the risk of bile duct injuries. Furthermore, ICG use was clinically safe, with no adverse reactions to the product.

Current Status and Trends of Minimally Invasive Gastrectomy in Korea

Since its introduction in the early 1990s, laparoscopic gastrectomy has been widely accepted for the treatment of gastric cancer worldwide. In the last decade, the Korean Laparoendoscopic Gastrointestinal Surgery Study group performed important clinical trials and exerted various efforts to enhance the quality of scientific knowledge and surgical techniques in the field of gastric cancer surgery. Laparoscopic gastrectomy has shifted to a new era in Korea due to recent advances and innovations in technology. Here, we discuss the recent updates of laparoscopic gastrectomy—namely, reduced-port, single-incision, robotic, image-guided, and oncometabolic surgery.

Real-Time Intraoperative Ureteral Identification in Minimally Invasive Colorectal Surgery: A Systematic Review

Background: Although colorectal surgery (CRS) has currently almost entirely standardized surgical procedures, it can still show pitfalls such as the intraoperative ureteral injury. Intraoperative ureteral identification (IUI) could reduce the ureteral injuries rate but evidence is still lacking. We aimed to analyze the utility and the effectiveness of real-time IUI in minimally invasive CRS. Materials and Methods: A systematic review was performed examining available data on randomized and nonrandomized studies evaluating the utility of intraureteral fluorescence dye (IFD) and lighted ureteral stent (LUS) for intraoperative identification of ureters in CRS, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) standards. Primary endpoint was ureteral injuries rate. Secondary endpoints included acute kidney injury, hematuria, urinary tract infections (UTI), and fluorescence assessment. Results: After literature search, 158 studies have been recorded, 36 studies underwent full-text reviews and 12 studies met inclusion criteria. Overall, out of a total of 822 patients who successfully received IUI, 3 (0.33%) patients experienced ureteral injury. Hematuria was reported in 689 (97.6%) of patients following LUS-guided surgery and in 1 (2%) patient following IFD-guided surgery, although transient in all cases. UTI was reported in 15 (3.3%) LUS-guided resections and in 1 (2%) IFD-guided resections. Acute kidney injury occurred in 23 (2.5%) LUS-guided surgery and 1 (1%) IFD-guided surgery. Conclusions: Real-time ureteral identification techniques could represent a valid solution in complex minimally invasive CRS, safely, with no time consuming and always reproducible by surgeons. Prospective studies will be needed to confirm these findings.

Fluorescence imaging in the surgical management of liver cancers: Current status and future perspectives

Over the last decades, imaging technologies have got significant developments and become indispensable in the surgical management of liver cancers. Real-time navigation afforded by intraoperative images has a significant impact on the success of liver surgeries. Fluorescence imaging in the near-infrared spectrum has shown potential for tumor detection and image-guided surgery in clinics. While predominantly focused on indocyanine green (ICG) imaging, there is also accelerated development of more specific molecular tracers. Compared to passive targeting contrast agents ICG, active targeting and activatable probes both shed new light for intraoperative navigation owing to the higher degree of specificity for the tumor target. A variety of fluorescence imaging probes have been developed to target biomarkers unique to cancer cells or tumor microenvironment and demonstrated promising results. In this review, we provide a comprehensive update on preclinical development and clinical applications of fluorescence imaging in the surgical management of liver cancers. By highlighting the current status, we aim to offer insight into the challenges and opportunities for further investigation.

Feasibility and educational value of fluorescence cholangiography in laparoscopic cholecystectomy

INTRODUCTION

Near-infrared fluorescence cholangiography during a laparoscopic cholecystectomy has become widely accepted as a useful auxiliary tool to visualize the extrahepatic biliary structures. We investigated the feasibility and educational value of a method with longer interval between the administration of indocyanine green and the imaging of these structures.

METHODS

Approximately 18 hours before their surgery, patients (n = 51) were intravenously administered 0.25 mg/kg of indocyanine green. Each laparoscopic cholecystectomy was performed under fluorescence imaging in combination with white-light imaging. Operative outcomes including visualization of the extrahepatic biliary structures and operative time were compared between the patients on whom board-certified surgeons operated (feasibility phase; n = 18) and the patients on whom a surgery resident operated (educational phase; n = 33).

RESULTS

There were no adverse events related to the longer interval method. The visualization rates of extrahepatic biliary structures were comparable between the two phases. Both the mean time to divide the cystic duct and the mean time to remove the gallbladder in the educational phase were significantly longer than those in the feasibility phase (68.2 vs 24.4 minutes and 30.2 vs 15.8 minutes, P < .001 each). There was no significant difference in other operative outcomes. The operative time learning curve did not decrease with a resident's experience.

CONCLUSIONS

Fluorescence cholangiography with the longer interval method was feasible and could identify the extrahepatic biliary structures irrespective of the surgeon's experience; however, it did not decrease the operative time with experience.

Laparoscopic cholecystectomy in a swine model using a novel near-infrared fluorescent IV dye (BL-760)

BACKGROUND AND OBJECTIVES

Bile duct injury during laparoscopic cholecystectomy has an incidence rate of 1%-2% and commonly appears under conditions of severe inflammation, adhesion, or unexpected anatomical variations. Despite the difficulties and rising concerns of identifying bile duct during surgeries, surgeons do not have a specific modality to identify bile duct except intraoperative cholangiography. While no biliary-specific fluorescent dye exists for clinical use, our team has previously described the development of a preclinical biliary-specific dye, BL-760. Here, we present our study of laparoscopic cholecystectomy using the fluorescent dye in a swine model.

STUDY DESIGN/MATERIALS AND METHODS

With an approval from Institutional Animal Care and Use Committee, two 20-25 kg swine underwent laparoscopic abdominal surgery using a Food and Drug Administration-cleared fluorescent laparoscopic system. Images of the liver and gallbladder were taken both before and after intravenous injection of the novel fluorescent dye. The dye was dosed at 60 μg/kg and injected via the ear vein. The amount of time taken to visualize fluorescence in the biliary tract was measured. Fluorescent signal was observed after injection, and target-to-background ratio (TBR) of the biliary tract to surrounding cystic artery and liver parenchyma was measured.

RESULTS

Biliary tract visualization under fluorescent laparoscopy was achieved within 5 min after the dye injection without any adverse effects. Cystic duct and extrahepatic duct were clearly visualized and identified with TBR values of 2.19 and 2.32, respectively, whereas no fluorescent signal was detected in liver. Cystic duct and artery were successfully ligated by an endoscopic clip applier with the visual assistance of highlighted biliary tract images. Laparoscopic cholecystectomy was completed within 30 min in each case without any complications.

CONCLUSIONS

BL-760 is a novel preclinical fluorescent dye useful for intraoperative identification and visualization of biliary tract. Such fluorescent dye that is exclusively metabolized by liver and rapidly excreted into biliary tract would be beneficial for all types of hepato-biliary surgeries. With the validation of additional preclinical data, this novel dye has potential to be a valuable tool to prevent any iatrogenic biliary injuries and/or bile leaks during laparoscopic abdominal and liver surgeries.

Initial experience of intraoperative fluorescent cholangiography during laparoscopic cholecystectomy: A retrospective study

Background

Fluorescent cholangiography (FC) during laparoscopic cholecystectomy (LC) is a novel method to facilitate real-time visualization of extrahepatic biliary structures that avoiding risk of bile duct injury. Aims of this study are to investigate the feasibility and the safety of FC during LC.

Method

We evaluated the outcomes of FC during elective LC at our hospital from August 2017 to April 2018. Fifty-five patients who underwent FC during elective LC were enrolled in this study. Demographic and peri-operative data were recorded and analyzed. The primary endpoints were visualization rate of FC during LC. The secondary endpoint was the optimal conditions and technical details for FC included to detect any potential adverse event.

Results

The visualization rate after FC of the cystic duct, common hepatic duct and common bile duct were increased significantly compared to before FC. The identification rate of the cystic duct and common bile duct were not associated with BMI and history of acute cholecystitis.

Conclusions

FC enabled real-time visualization of extrahepatic biliary structures during LC. FC appears to be a safe and efficient approach for elective LC.

•

Bile duct injury is one of the most complication of laparoscopic cholecystectomy.

•

Fluorescent cholangiography is offer real-time detection of the biliary anatomy.

•

Cholangiogram was associated with a low incidence of bile duct injury.

The role of indocyanine green cholangiography in minimally invasive surgery

INTRODUCTION

Near-infrared fluorescent cholangiography (NIFC) using indocyanine green (ICG) is increasingly used to aid in the identification of extrahepatic biliary anatomy. The use of ICG cholangiography for laparoscopic cholecystectomy is suggested to be safe and feasible. This article aimed at reviewing the dosage and timing of the intravenous administration of ICG, its efficacy and potential usage.

EVIDENCE ACQUISITION

MEDLINE and PubMed searches were performed using the key words "fluorescent cholangiography," "ICG cholangiography," "near-infrared fluorescent cholangiography" and "laparoscopic cholecystectomy" to identify relevant articles published in English during the years of 2010 to 2020. Reference lists from the articles were reviewed to identify additional pertinent articles.

EVIDENCE SYNTHESIS

Several factors can influence the quality of the fluorescence imaging, including the dose and timing of ICG injection, liver function, the thickness of fatty tissue and the presence of inflamed tissues due to acute pathology. Various devices tested also have a different sensitivity to the fluorescence signal. RCTs showed fluorescence cholangiography were comparable to traditional intraoperative cholangiogram in visualizing the extrahepatic biliary anatomy. However, there is still no consensus in the dosing of ICG and the time interval between ICG injection and detection of biliary fluorescence. Fluorescence cholangiography's ability to enhance such visualization can potentially reduce bile duct injury risks and shorten the operative time. However, no valuable data for bile duct injury prevention or detection could be retrieved.

CONCLUSIONS

NIFC is demonstrated as a safe, non-irradiating technique to identify and aid in the visualization of extrahepatic biliary anatomy. Laparoscopic cholecystectomy with real-time NIFC enables a better visualization and identification of biliary anatomy and therefore it is potentially as a means of increasing the safety of laparoscopic cholecystectomy. Whether this translates into reducing complication rates must still be determined. The dosage and timing of the intravenous administration of ICG relative to the operative procedure still requires optimization to ensure reliable images.

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

Indocyanine green (ICG) near-infrared fluoroscopy has been recently implemented in pure laparoscopic donor hepatectomy (PLDH). This study aims to quantitatively evaluate the effectiveness of ICG fluoroscopy during liver midplane dissection in PLDH and to demonstrate that a single injection of ICG is adequate for both midplane dissection and bile duct division. Retrospective analysis was done with images acquired from recordings of PLDH performed without ICG (pre-ICG group) from November 2015 to May 2016 and with ICG (post-ICG group) from June 2016 to May 2017. 30 donors from the pre-ICG group were compared with 46 donors from the post-ICG group. The operation time was shorter (P = 0.002) and postoperative peak aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were lower (P = 0.031 and P = 0.019, respectively) in the post-ICG group than the pre-ICG group. Within the post-ICG group, the color intensity differences between the clamped versus nonclamped regions in the natural, black-and-white, and fluorescent modes were 39.7 ± 36.2, 89.6 ± 46.9, and 19.1 ± 36.8 (mean ± SD, P < 0.001), respectively. The luminosity differences were 37.2 ± 34.5, 93.8 ± 32.1, and 26.7 ± 25.7 (P < 0.001), respectively. Meanwhile, the time from when ICG was injected to when the near-infrared camera was turned on for bile duct visualization was 85.6 ± 25.8 minutes. All grafts received from the 46 donors were successfully transplanted. In conclusion, ICG fluoroscopy helps to reduce operation time and lower postoperative AST/ALT levels. ICG injection visualized with black-and-white imaging is most effective for demarcating the liver midplane during PLDH. A single intravenous injection of ICG is sufficient for midplane dissection as well as bile duct division.

Micro-Dosing of Indocyanine Green for Intraoperative Fluorescence Cholangiography

BACKGROUND

Surgery involving the biliary tree is common but has the potential for serious complications. Adjuncts such as intraoperative cholangiogram and, more recently, indocyanine green (ICG) fluorescence cholangiography, have been used to more accurately define the relevant anatomy and decrease the risk of common bile duct injury. The optimal ICG dose is unknown, but the most commonly cited dose in the literature is 2.5 mg. We describe our experience using micro-dosing of ICG as proof-of-concept for its successful use in the identification of biliary structures.

METHODS

A video library from a variety of hepatobiliary surgeries which included micro-dosing of ICG was compiled between 2018 and 2020. These videos were retrospectively reviewed and graded for the degree of visualization of biliary structures (complete, partial, none) and the degree of background liver fluorescence (significant, moderate, minimal).

RESULTS

Overall, 40 videos were reviewed; 70% were minimally invasive cholecystectomies. Micro-dosing was used in all patients; complete visualization was achieved in 52.5% of the patients, partial visualization in 40%, and no visualization in 7.6%. Eighty percent of patients had minimal to moderate background fluorescence. Despite ICG micro-dosing, 20% of the patients still had significant liver dye uptake.

CONCLUSION

ICG cholangiography is an alternative to more invasive means of intraoperative imaging during biliary surgery, but the optimal dose of ICG is unknown. We have used a 0.05 mg micro-dose of ICG to successfully visualize biliary structures and reduce background liver fluorescence. This preliminary report can be used to develop further studies into whether micro-dosing of ICG is associated with improved clinical outcomes.

INDOCYANINE GREEN FLUORESCENCE IMAGING IN ROBOTIC SURGERY: STATE OF ART, TIPS AND TRICKS IN CURRENT APPLICATIONS

BACKGROUND

Fluorescent imaging with indocyanine green is an emerging technology whose benefits are put in perspective.

OBJECTIVE

This article reports essential principles and approaches of intraoperative fluorescence in general surgery bringing familiarity to its practical usage. Our group describes possible pitfalls and provides tips and tricks for training surgeons making their attempts easier and reproducible during practice.

METHODS

This study overviews the most structured concepts, practical applications and its tricks in robotic fluorescence guided imaging surgery with indocyanine green. Possible pitfalls are emphasized and emerging fields of application are put in a perspective.

RESULTS

Guided information and practical applications in several surgical fields are described for a safe and reproducible indocyanine green fluorescence imaging use.

CONCLUSION

Robotic assisted surgery combined to fluorescence imaging technology represents a logical evolution in image guided surgery and technology familiarity with guided information may represent a wider and safer spectrum of use in surgeons' hands.

Application of near-infrared fluorescent cholangiography using indocyanine green in laparoscopic cholecystectomy

OBJECTIVE

Near-infrared fluorescence cholangiography (NIRF-C) can help to identify the bile duct during laparoscopic cholecystectomy. This retrospective study was performed to investigate the effect of NIRF-C in laparoscopic cholecystectomy.

METHODS

Consecutive patients who underwent NIRF-C-assisted laparoscopic cholecystectomy (n = 34) or conventional laparoscopic cholecystectomy (n = 36) were enrolled in this study. Identification of biliary structures, the operation time, intraoperative blood loss, and postoperative complications were analyzed.

RESULTS

Laparoscopic cholecystectomy was completed in all patients without conversion to laparotomy. The median operation time and intraoperative blood loss were not significantly different between the two groups. No intraoperative injuries or postoperative complications occurred in either group. In the NIRF-C group, the visualization rate of the cystic duct, common bile duct, and common hepatic duct prior to dissection was 91%, 79%, and 53%, respectively. The success rate of cholangiography was 100% in the NIRF-C group. NIRF-C was more effective for visualizing biliary structures in patients with a BMI of <25 than >25 kg/m².

CONCLUSIONS

NIRF-C is a safe and effective technique that enables real-time identification of the biliary anatomy during laparoscopic cholecystectomy. NIRF-C helps to improve the efficiency of dissection.

Understanding intraoperative fluorescent cholangiography: ten steps for an effective and successful procedure

BACKGROUND

Common bile duct injuries (BDI) during laparoscopic cholecystectomy (LC) continue to be the source of morbidity and mortality. The reason for BDI is mostly related to the misidentification of the extrahepatic bile duct structures and the anatomic variability. Near-infrared fluorescent cholangiography (NIFC) has proven to enhance visualization of extrahepatic biliary structures during LCs. The purpose of this study was to describe the most important steps in the performance of NIFC.

METHODS

In accordance to the most current surgical practice of LC at our institution, a consensus was achieved on the most relevant steps to be followed when utilizing NIFC. Dose of indocyanine green (ICG), time of administration, and identification of critical structures were previously determined based on prospective and randomized controlled studies performed at CCF.

RESULTS

The ten steps identified as critical when performing NIFC during LC are preoperative administration of ICG, exposure of the hepatoduodenal ligament, initial anatomical evaluation, identification of the cystic duct and common bile duct junction, the cystic duct and its junction to the gallbladder, the CHD, the common bile duct, accessory ducts, cystic artery and, time-out and identification of Calot's triangle, and evaluation of the liver bed.

CONCLUSIONS

Routine use of NIFC is a useful diagnostic tool to better visualize the extrahepatic biliary structures during LC. The implementation of specific standardized steps might provide the surgeon with a better algorithm to use this technology and consequently reduce the incidence of BDI.

Indocyanine green fluorescence navigation for hepatocellular carcinoma with bile duct tumor thrombus: a case report

Background

Bile duct tumor thrombus (BDTT) is one of the features of advanced hepatocellular carcinoma (HCC). In the resection of HCC with BDTT, it is important to detect the BDTT tip to decide the appropriate point of bile duct division. In this regard, the efficacy of indocyanine green (ICG) fluorescence navigation has been confirmed for the detection of HCC, whereas its utility for BDTT has not yet been reported. Herein, we describe our experience with right hepatectomy for HCC with BDTT using ICG fluorescence navigation.

Case presentation

A 72-year-old woman had experienced local recurrences of HCC after radiofrequency ablation, with BDTT reaching the confluence of the right anterior branch and posterior branch. Right hepatectomy was planned, and 2.5 mg of ICG was injected one day before surgery. After transection of the liver parenchyma, the right liver was connected with only the right hepatic duct. ICG fluorescence imaging visualized the tip of BDTT in the bile duct with clear contrast; the proximal side (hepatic side) of the right hepatic duct showed stronger fluorescence than the distal side (duodenal side). The bile duct was divided at the distal side of the BDTT border, and the tip of BDTT was recognized into the resected right hepatic duct without laceration. The patient had an uneventful postoperative course and currently lives without recurrences for 6 months.

Conclusions

ICG fluorescence navigation assisted in the precise resection of the bile duct in HCC with BDTT.

Whole-Body Fluorescence Imaging in the Near-Infrared Window

Fluorescence imaging is one of the most widely used in vivo imaging methods for both fundamental research and clinical practice. Due to the reduced photon scattering, absorption, and autofluorescence in tissues, the emerging near-infrared (NIR) imaging (650-1700 nm) can afford deep tissue imaging with high spatiotemporal resolution and in vivo report the anatomical structures as well as the physiological activities in a whole-body level. Here, we give a brief introduction to fluorescence imaging in the first NIR (NIR-I, 650-950 nm) and second NIR (NIR-II, 1000-1700 nm) windows, summarize the recently developed NIR fluorophores and their applications in whole-body vascular system imaging, precision cancer theranostics, and regenerative medicine. Finally, the clinical applications and future prospects of in vivo NIR fluorescence imaging are also discussed.

Indocyanine green administration a day before surgery may increase bile duct detectability on fluorescence cholangiography during laparoscopic cholecystectomy

BACKGROUND

The optimal indocyanine green (ICG) administration protocol for fluorescence cholangiography during laparoscopic cholecystectomy (LC) has yet to be determined.

METHODS

A prospective study including 20 cases of ICG fluorescence-navigated LC was conducted. Accordingly, the first 10 patients were administered 2.5 mg of ICG on the day of surgery after intubation (surgery-day group), while the remaining 10 consecutive patients were administered 0.25 mg/kg of ICG on the evening before surgery (one-day-before group). Fluorescence intensity (FI) of each tissue and FI ratios were then compared between both groups.

RESULTS

The median interval between observation and ICG administration was 27 minutes and 16 hours 24 minutes in the surgery-day and one-day-before group, respectively. Although FI values for the common bile duct (CBD), liver, and hepatoduodenal ligament (HDL) were significantly lower in the one-day-before group than in the surgery-day group, CBD- , 0.6-1.2 vs 2.5, 0.9 = -4.8; P < .001), and CBD-HDL contrast (1.7, 1.4-2.4 vs 2.3, 1.5-13.3; P = .038) were significantly higher in the one-day-before group than in the surgery-day group.

CONCLUSION

ICG administration a day before LC may offer better CBD background contrast compared to administration just prior to surgery.

Extrahepatic biliary tract visualization using near-infrared fluorescence imaging with indocyanine green: optimization of dose and dosing time

BACKGROUND

The dose and dosing time of indocyanine green (ICG) vary among fluorescence cholangiography (FC) studies. The purpose of this prospective, randomized, exploratory clinical trial was to optimize the dose and dosing time of ICG.

METHODS

PubMed was searched to determine the optimal dose. To optimize the dosing time of ICG, a clinical trial was designed with two parts. The first part included patients with T tubes for more than 1 month. After the patient was injected with ICG, bile was collected at 10 time points to explore the change and trends of bile fluorescence intensity (FI). In addition, the results of the first experiment were used to setup a randomized controlled trial (RCT) that aimed to find the optimal dosing timing for ICG injections for laparoscopic cholecystectomy (LC). During surgery, imaging data were collected for analysis.

RESULTS

After performing a systematic review, the ICG injection dose for each patient in the clinical trial was 10 mg. Five patients were included in the first part of the study. Bile collected 8 h after ICG injection had a higher FI than bile collected at other time points (p < 0.05), and the FI of bile collected 20 h after ICG injection was nearly zero. In the second part of the experiment, 4 groups of patients (6 patients per group) were injected with 10 mg ICG at 8, 10, 12 and 14 h prior to surgery. The distribution of bile duct FI (p = 0.001), liver FI (p < 0.001), and common bile duct (CBD)-to-liver contrast (p = 0.001) were not the same in each group. Further analysis with the Bonferroni method revealed the following: (1) the FI of the CBD in the 8 h group was significantly different from that in the 14 h group (adjusted p < 0.001); (2) the liver FI of the 8 h group was higher than that of the 10 h group (adjusted p = 0.042) and the 14 h group (adjusted p < 0.001); and (3) the CBD-to-liver contrast of the 8 h group was lower than that of the 10 h group (adjusted p = 0.013) and the 14 h group (adjusted p = 0.001).

CONCLUSION

ICG FC enables the real-time identification of extrahepatic bile ducts. The optimal effect of FC can be achieved by performing 10 mg ICG injections 10 to 12 h prior to surgery.

Fluorescence-guided hepatobiliary surgery with long and short wavelength fluorophores

Importance

Fluorescence-guided surgery (FGS) is a potentially powerful tool for hepatobiliary (HPB) surgery. The high sensitivity of fluorescence navigation is especially useful in settings where tactile feedback is limited.

Objective

The present narrative review evaluates literature on the use of FDA-approved fluorophores such as methylene blue (MB), 5-aminolevulinic acid (5-ALA), and indocyanine green (ICG) for clinical intra-operative image-guidance during HPB surgery.

Evidence Review

Approaches such as dosing, timing, imaging devices and comparative endpoints are summarized. The feasibility and safety of fluorophores in visualizing the biliary tree, identify biliary leaks, outline anatomic hepatic segments, identify tumors, and evaluate perfusion and graft function in liver transplants are discussed.

Findings

Tumor-specific probes are a promising advancement in FGS with a greater degree of specificity. The current status of tumor-specific probes being evaluated in clinical trials are summarized.

Conclusions and Relevance for Reviews

Relevant discussion of promising tumor-specific probes in pre-clinical development are discussed. Fluorescence-guidance in HPB surgery is relatively new, but current literature shows that the dyes are reliably able to outline desired structures with a variety of dosing, timing, and imaging devices to provide real-time intra-operative anatomic information to surgeons. Development of tumor-specific probes will further advance the field of HPB surgery especially during oncologic resections.

Fluorescence-based cholangiography: preliminary results from the IHU-IRCAD-EAES EURO-FIGS registry

INTRODUCTION

Near-infrared fluorescence cholangiography (NIRF-C) is a popular application of fluorescence image-guided surgery (FIGS). NIRF-C requires near-infrared optimized laparoscopes and the injection of a fluorophore, most frequently Indocyanine Green (ICG), to highlight the biliary anatomy. It is investigated as a tool to increase safety during cholecystectomy. The European registry on FIGS (EURO-FIGS: www.euro-figs.eu ) aims to obtain a snapshot of the current practices of FIGS across Europe. Data on NIRF-C are presented.

METHODS

EURO-FIGS is a secured online database which collects anonymized data on surgical procedures performed using FIGS. Data collected for NIRF-C include gender, age, Body Mass Index (BMI), pathology, NIR device, ICG dose, ICG timing of administration before intraoperative visualization, visualization (Y/N) of biliary structures such as the cystic duct (CD), the common bile duct (CBD), the CD-CBD junction, the common hepatic duct (CHD), Visualization scores, adverse reactions to ICG, operative time, and surgical complications.

RESULTS

Fifteen surgeons (12 European surgical centers) uploaded 314 cases of NIRF-C during cholecystectomy (cholelithiasis n = 249, cholecystitis n = 58, polyps n = 7), using 4 different NIR devices. ICG doses (mg/kg) varied largely (mean 0.28 ± 0.17, median 0.3, range: 0.02-0.62). Similarly, injection-to-visualization timing (minutes) varied largely (mean 217 ± 357; median 57), ranging from 1 min (direct intragallbladder injection in 2 cases) to 3120 min (n = 2 cases). Visualization scores before dissection were significantly correlated, at univariate analysis, with ICG timing (all structures), ICG dose (CD-CBD), device (CD and CD-CBD), surgeon (CD and CD-CBD), and pathology (CD and CD-CBD). BMI was not correlated. At multivariate analysis, pathology and timing remained significant factors affecting the visualization scores of all three structures, whereas ICG dose remained correlated with HD visualization only.

CONCLUSIONS

The EURO-FIGS registry has confirmed a wide disparity in ICG dose and timing in NIRF-C. EURO-FIGS can represent a valuable tool to promote and monitor FIGS-related educational and consensus activities in Europe.

Avoidance of bile duct injury during laparoscopic liver cyst fenestration using indocyanine green: A case report

By administering ICG test immediately before laparoscopic liver cyst fenestration, the biliary tract can be easily identified and intraoperative bile duct damage and postoperative bile fistula formation can be avoided, as demonstrated in this case.