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

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.

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.

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.

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.

Near-infrared image-guided laparoscopic omental flap for breast cancer

BACKGROUND

Near-infrared (NIR) imaging with indocyanine green (ICG)-enhanced fluorescence is widely used in laparoscopic surgery. This study aimed to evaluate this technique's feasibility and usefulness in intraoperatively assessing vascular perfusion in a laparoscopically harvested omental flap.

MATERIALS AND SURGICAL TECHNIQUES

From March 2015 to February 2016, we prospectively evaluated patients undergoing breast cancer surgery followed by immediate breast reconstruction using a laparoscopically harvested omental flap. After laparoscopic preparation of the pedicled graft, the perfusion area of the omental graft was evaluated by using intraoperative Doppler ultrasonography and NIR imaging with intravenous ICG injection. Graft viability was evaluated by using Doppler ultrasonography 2 days postoperatively; for cosmetic outcome, Breast Cancer Conservative Treatment Cosmetic Results software was used 1 month postoperatively.

DISCUSSION

The laparoscopic harvesting of an omental flap was successfully performed in eight patients without conversion to open surgery. The mean time to the initial detection of ICG-enhanced fluorescence uptake was 3.25 ± 1.16 minutes. On intraoperative Doppler ultrasonography, a pulseless area ≥10% was detected in five patients (62.5%). However, NIR imaging revealed no patients had an ischemic portion ≥10%. There were no ICG-related intraoperative or postoperative complications. All patients showed patent vessels on Doppler ultrasonography 2 days postoperatively. Cosmetic outcomes were mostly favorable 1 month postoperatively. The Breast Cancer Conservative Treatment Cosmetic Results evaluation 1 month postoperatively showed excellent, good, and fair results, with no poor scores. With regard to vascular perfusion, ICG-enhanced NIR imaging is a feasible and useful tool for harvesting a laparoscopic omental flap in breast cancer patients.

Application of Fluorescent Dyes in Visceral Surgery: State of the Art and Future Perspectives

Background

Through the improvement and implementation of advanced intraoperative imaging, the indications for intraoperative fluorescence have spread to various fields of visceral surgery. Indocyanine green (ICG)-based fluorescence angiography and the imaging systems using this certain dye are currently the cornerstone of intraoperative, fluorescence-based medical imaging.

Summary

The article focuses on principles and approaches of intraoperative fluorescence in general surgery. The current clinical practice of intraoperative fluorescence and its evidence are described. Emerging new fields of application are put in a perspective. Furthermore, the technique and possible pit-falls in the performance of intraoperative ICG fluorescence angiography are described in this review article.

Key Messages

Overall growing evidence suggests that intraoperative fluorescence imaging delivers valuable additional information to the surgeon, which might help to perform surgery more exactly and reduce perioperative complications. Perfusion assessment can be a helpful tool when performing critical anastomoses. There is evidence from prospective and randomized trials for the benefit of intraoperative ICG fluorescence angiography during esophageal reconstruction, colorectal surgery, and surgery for mesenteric ischemia. Most studies suggest the administration of 2.5-10 mg of ICG. Standardized settings and documentation are essential. The benefit of ICG fluorescence imaging for gastrointestinal sentinel node detection and detection of liver tumors and colorectal metastases of the liver cannot clearly be estimated duo to the small number of prospective studies. Critical points in the use of intraoperative fluorescence imaging remain the low standardization and reproducibility of the results and the associated difficulty in comparing the results of the existing trials. Furthermore, little is known about the influence of hemodynamic parameters on the quantitative assessment of ICG fluorescence during surgery.

Intracholecystic administration of indocyanine green for fluorescent cholangiography during laparoscopic cholecystectomy-A two-case report

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It is difficult to visualize extra-hepatic biliary anatomy clearly because of long-presence of ICG in liver when administered intravenously.

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Intracholecystic ICG injection illuminates extra-hepatic biliary tree preferentially thus reducing background hepatic noise.

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Surgeons can experience more satisfaction with the use of fluorescent cholangiography during laparoscopic cholecystectomy when the intracystic route of ICG administration is utilized.

Introduction

The utility of intracystic administration of indocyanine green for near-infrared fluorescent cholangiography in acute calculous cholecystitis initially treated with percutaneous transhepatic gallbladder drainage (PTGBD) was described in this report.

Presentation of case

Two cases who underwent near-infrared fluorescent cholangiography guided interval laparoscopic cholecystectomy two weeks post-PTGBD were studied retrospectively. Both patients were diagnosed with moderate acute calculous cholecystitis based on diagnostic criteria of the Tokyo guidelines. Two routes of indocyanine green administration were utilized during surgery, first through direct intracystic administration through PTGBD tube (5 ml of 12.5 mg ICG) to achieve critical view of safety and then intravenous administration (1 ml of 2.5 mg ICG) to visualize cystic artery.

Discussion

Both patients had critical view of safety visualized clearly with ICG with the operation time of 84 and 125 min in cases 1 and 2, respectively without any intra or postoperative complications.

Conclusion

In comparison with intravenous ICG administration, trans-PTGBD ICG route can provide better signal-to-noise ratio by avoiding hepatic fluorescence and thus increasing the bile duct to liver contrast. However, ICG may enter the lymphatic system through necrotic and inflammatory gallbladder mucosa, of which lymph spillage during gallbladder dissection can obscure the fluorescent view.

Fluorescence or X-ray cholangiography in elective laparoscopic cholecystectomy: a randomized clinical trial

BACKGROUND

Safe laparoscopic cholecystectomy may necessitate biliary imaging, and non-invasive fluorescence cholangiography may have advantages over contrast X-ray cholangiography. This trial compared fluorescence and X-ray cholangiography for visualization of the critical junction between the cystic, common hepatic and common bile ducts.

METHODS

This non-inferiority blinded RCT included patients who had either intraoperative fluorescence cholangiography using 0·05 mg/kg indocyanine green or X-ray cholangiography during elective laparoscopic cholecystectomy.

RESULTS

Between March 2015 and August 2018, a total of 120 patients were randomized (60 in each group). There were no drop-outs and 30-day follow-up data were available for all patients. In intention-to-treat analysis, there was no difference between the fluorescence and X-ray cholangiography groups in ability to visualize the critical junction (49 of 60 versus 51 of 60 respectively; P = 0·230). Fluorescence cholangiography was faster by a few minutes: median 2·0 (range 0·5-5·0) versus 4·8 (1·3-17·6) min (P < 0·001).

CONCLUSION

Fluorescence cholangiography was confirmed to be non-inferior to X-ray cholangiography in visualizing the critical junction during laparoscopic cholecystectomy. Registration number: NCT02344654 ( http://www.clinicaltrials.gov).

The outcome of real-time evaluation of biliary flow using near-infrared fluorescence cholangiography with Indocyanine green in biliary atresia surgery

BACKGROUND

Indocyanine green (ICG) fluorescence imaging is a promising tool for intraoperative decision-making. The aim of this study was to evaluate the utility of near-infrared fluorescence cholangiography (NIR-FCG) with ICG in primary surgery for biliary atresia (BA).

METHODS

We performed NIR-FCG with ICG in 10 BA patients and observed the fluorescence of their hilar micro-bile ducts and hilar exudate in order to assess the appropriate level at which to dissect the hilar fibrous corn. We compared the jaundice outcome of 10 patients using NIR-FCG (Group A) to that of 35 historical patients in whom NIR-FCG had not been used (Group B).

RESULTS

The mean age of patients was 74.8 days. The classification of BA was type I in two cases and type-III in eight cases. NIR-FCG visualized the hilar micro-bile ducts, and the incidence of positive fluorescence was 80%. The ratio of postoperative normalization of hyperbilirubinemia in Group A was significantly higher than that in Group B (1.0 vs. 0.65, p < 0.05).

CONCLUSION

NIR-FCG provided important objectifiable information about the biliary structures in surgery of BA. Although the number of cases was small, our results suggest that NIR-FCG may be useful for improving the outcome of primary surgery for BA.

TYPE OF STUDY

Study of Diagnostic Test.

LEVEL OF EVIDENCE

Level III.

Clinical application and technical standardization of indocyanine green (ICG) fluorescence imaging in pediatric minimally invasive surgery

PURPOSE

We reported our preliminary experience using ICG fluorescence in pediatric minimally invasive surgery (MIS) with the aim to standardize indications, dose, timing, and modality of administration of ICG according to different organs.

METHODS

ICG technology was adopted in 46 MIS procedures performed in our unit over the last 18 months: 30 left varicocele repairs; 5 cholecystectomies in obese adolescents; 3 tumor excisions; 3 nephrectomies; 2 partial nephrectomies; 3 lymphoma excisions. ICG solution was injected intravenously in all cases except for varicocelectomy in which it was injected into the testis. The ICG injection was performed intra-operatively in all cases except for cholecystectomy in which it was injected 18 h prior to the procedure.

RESULTS

All procedures were completed laparoscopically without conversions or intra-operative complications. No adverse or allergic reactions to ICG were reported.

CONCLUSION

Our preliminary experience showed that ICG fluorescence is a safe, useful, and versatile technique to adopt in pediatric MIS to achieve a better identification of anatomy and an easier surgical dissection or resection in challenging cases. Currently, the main indications are varicocelectomy, difficult cholecystectomy, tumor excision, nephrectomy, and partial nephrectomy. The main limitation is the needing of a special equipment to use ICG technology.

Characterization and validation of multimodal annihilation-gamma/near-infrared/visible laparoscopic system

Minimally invasive robotic surgery using fluorescence-guided images with a video laparoscope has been widely used because of its advantages of small incision, fast recovery time, and efficiency. However, the penetration depth limitation of fluorescence is a disadvantage caused by the absorption and scattering in tissues and blood cells. If this limitation can be overcome by additional imaging modalities, the surgical procedure can be quite efficient and precise. High-energy annihilation-gamma photons have a stronger penetration capability than visible and fluorescence photons. To characterize and validate a multimodal annihilation-gamma/near-infrared (NIR)/visible laparoscopic imaging system, an internal detector composed of an annihilation-gamma detector and an optical system was assembled inside a surgical stainless pipe with an outer diameter of 15.8 mm and an external detector with a dimension of 100  ×  100  mm2 placed at the opposite side of the internal detector. Integrated images of 511-keV gamma rays, NIR fluorescence, and visible light were obtained simultaneously. The 511-keV gamma image could be clearly seen with the acquisition of 5 s, while NIR and visible images could be presented in real time. This multimodal system has the potential for improving the surgery time and the quality of patient care.

Fluorescence-Guided Surgery for Hepatoblastoma with Indocyanine Green

Fluorescence-guided surgery with indocyanine green (ICG) for malignant hepatic tumors has been gaining more attention with technical advancements. Since hepatoblastomas (HBs) possess similar features to hepatocellular carcinoma, fluorescence-guided surgery can be used for HBs, as aggressive surgical resection, even for distant metastases of HBs, often contributes positively to R0 (complete) resection and subsequent patient survival. Despite a few caveats, fluorescence-guided surgery allows for the more sensitive identification of lesions that may go undetected by conventional imaging or be invisible macroscopically. This leads to precise resection of distant metastatic tumors as well as primary liver tumors.

Routine near infra-red indocyanine green fluorescent cholangiography versus intraoperative cholangiography during laparoscopic cholecystectomy: a case-matched comparison

BACKGROUND

The aim is to evaluate safety and efficacy of near infra-red (NIR) indocyanine green (ICG) fluorescence structural imaging during laparoscopic cholecystectomy (LC) (Group A) and to compare perioperative data, including operative time, with a series of patients who underwent LC with routine traditional intraoperative cholangiography (IOC) (Group B).

METHODS

Forty-four patients with acute or chronic cholecystitis underwent NIR-ICG fluorescent cholangiography during LC. ICG was administered intravenously at different time intervals or by direct gallbladder injection during surgery. Fluorescence intensity and anatomy identification were scored according to a visual analogue scale between 1 (least accurate) and 5 (most accurate). Group B patients (n = 44) were chosen from a prospectively maintained database of patients who underwent LC with routine IOC, matched for age, sex, body mass index, and diagnosis with group A patients.

RESULTS

No adverse reactions were recorded. In group A, mean time between intravenous administration of ICG and surgery was 10.7 ± 8.2 (range 2-52) h. Administered doses ranged from 3.5 to 13.5 mg. Fluorescence was present in all cases, scoring ≥ 3 in 41 patients. Mean operative time was 86.9 ± 36.9 (30-180) min in group A and 117.9 ± 43.4 (40-220) min in group B (p = 0.0006). No conversion to open surgery nor bile duct injuries were observed in either group.

CONCLUSIONS

LC with NIR-ICG fluorescent cholangiography is safe and effective for early recognition of anatomical landmarks, reducing operative time as compared to LC with IOC, even when residents were the main operator. NIR-ICG fluorescent cholangiography was effective in patients with acute cholecystitis and in the obese. Data collection into large registries on the results of NIR-ICG fluorescent cholangiography during LC should be encouraged to establish whether this technique might set a new safety standard for LC.

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.

Targeting COX-1 by mofezolac-based fluorescent probes for ovarian cancer detection

Biomarkers of specific targets are becoming an essential objective for clinical unmet clinical needs to improve diseases early detection and increase patient overall survival. Ovarian cancer is among the highest mortality gynecological cancers. It is asymptomatic and almost always diagnosed at advanced stage. At five years from the first diagnosis the survival rate of ovarian cancer patients is only 30%. Cyclooxygenase (COX)-1 as opposed to COX-2 is known to be overexpressed in ovarian cancer. Therefore, fluorescent probes targeting COX-1 were designed and prepared in fair to good yields for its quantitatively detection in human ovarian cancer cell lines (OVCAR-3 and SKOV-3). In particular, both cytofluorimetric and immunofluorescent experiments showed that N-[4-(9-dimethylimino-9H-benzo[a]phenoxazin-5-ylamino)butyl]-2-(3,4-bis(4-methoxyphenyl)isoxazol-5-yl)acetamide chloride (11) enters into OVCAR-3 cells and is mainly localized on the membrane containing the COX-1. Membrane fluorescence emission represents about 80% of the total fluorescence measured in the whole cell, while the non-specific labeling represents only 20%. This result indicates that the intensity of fluorescence emission is almost exclusively attributable to 11 bound to COX-1 located on the membrane. Furthermore, no diffusion inside the cell occurs. IC₅₀hCOX-1 value of 11 determined by measuring the O₂ consumption during the bis-oxygenation of the arachidonic acid catalysed by COX-1 was found to be equal to 1.8 nM. Furthermore, 11 inhibits oCOX-1 with IC₅₀ = 6.85 nM and mCOX-2 with IC₅₀ = 269.5 nM; the corresponding selectivity index SI is equal to 39.3 against oCOX-1. 11 inhibits oCOX-1 at 0 min of incubation with 91% inhibition, whereas in the same time it does not inhibit mCOX-2. Fingerprints for Ligands and Proteins (FLAP) software calculations were performed to justify 11 higher COX-1 inhibitory potency than mofezolac (COX-1 IC₅₀ = 5.1 nM), which in turn is a moiety of 11. Specifically, the two compounds bind differently in the COX-1 active site.

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.

Efficacy of Assessing Intraoperative Bowel Perfusion with Near-Infrared Camera in Laparoscopic Gastric Cancer Surgery

BACKGROUND

Anastomotic leakage is a severe complication after gastric cancer surgery. Inadequate blood supply is regarded as an important risk factor. The aim of the study was to evaluate the feasibility and usefulness of intraoperative assessment of anastomotic vascular perfusion in gastric cancer surgery using near-infrared (NIR) camera imaging with indocyanine green (ICG)-enhanced fluorescence technique.

MATERIALS AND METHODS

From March 2015 to 2016, 30 patients undergoing laparoscopic gastrectomy for gastric cancer were prospectively evaluated. After completing the anastomosis, 2.5-5.0 mg of ICG was injected via peripheral veins. All anastomoses and resection margins were investigated using NIR camera to assess anastomotic perfusion. The assessment was performed using the adopted perfusion score of fluorescence activity, which ranged from 1 to 5 (1 = no uptake, and 5 = iso-fluorescent to all other segments).

RESULTS

Twenty-six distal gastrectomy (20 gastroduodenostomies, 6 gastrojejunostomies), 3 total gastrectomies (TG), and 1 pylorus-preserving gastrectomy were performed. The gap of visualization was 4.1 ± 3.2 minutes (range, 2-15) after ICG injection. Twenty-three of 30 patients (76.7%) showed technically successful ICG visualization. Among gastroduodenostomies, the average scores for gastric and duodenal sides were 3.5 and 3.7. Among gastrojejunostomies, the average scores for gastric, jejunal, and duodenal stump sides were 3.5, 4.0, and 3.8 (jejunojejunostomy, 3.5). Among TG, the average scores for esophagojejunostomy, duodenal stump, and jejunojejunostomy were 3.7, 4.0, 4.0, and 4.7. One case of leakage occurred in this study. Other complications included fluid collection and stenosis in 1 patient each.

CONCLUSIONS

This study showed intraoperative ICG angiography using NIR camera is feasible and provides imaging of anastomotic blood flow. Further studies are needed for practice.

Fluorescence Imaging for Minimally Invasive Cancer Surgery

This article demonstrates surgical techniques of intraoperative fluorescence imaging using indocyanine green, focusing on its application in minimally invasive hepatobiliary and pancreatic surgery. In this area, indocyanine green fluorescence imaging has been applied to liver cancer identification, fluorescence cholangiography, delineation of hepatic segments, and fluorescence angiography and perfusion assessment. The development of target-specific fluorophores and advances in imaging technology will allow real-time intraoperative fluorescence imaging to develop into an essential intraoperative navigation tool. This property may contribute to enhancing both accuracy and safety of minimally invasive surgery.

Optimal timing of preoperative indocyanine green administration for fluorescent cholangiography during laparoscopic cholecystectomy using the PINPOINT® Endoscopic Fluorescence Imaging System

INTRODUCTION

The PINPOINT® Endoscopic Fluorescence Imaging System (Novadaq, Mississauga, Canada) allows surgeons to visualize the bile ducts during laparoscopic cholecystectomy. Surgeons can continue operation while confirming the bile ducts' fluorescence with a bright-field/color image. However, strong fluorescence of the liver can interfere with the surgery. Here, we investigated the optimal timing of indocyanine green administration to allow fluorescent cholangiography to be performed without interference from the liver fluorescence.

METHODS

A total of 72 patients who underwent laparoscopic cholecystectomy were included in this study. The timing of indocyanine green administration was set immediately before surgery and at 3, 6, 9, 12, 15, 18, and 24 h before surgery. The luminance intensity ratios of gallbladder/liver, cystic duct/liver, and common bile duct/liver were measured using the ImageJ software (National Institutes of Health, Bethesda, USA). Visibility of the gallbladder and bile ducts was classified into three categories (grades A, B, and C) based on the degree of visibility in contrast to the liver.

RESULTS

The luminance intensity ratio for the gallbladder/liver, cystic duct/liver, and common bile duct/liver was ≥1 in the 15-, 18-, and 24-h groups. The proportion of cases in which evaluators classified the visibility of the gallbladder and bile ducts as grade A (best visibility) reached a peak in the 15-h group and decreased thereafter.

CONCLUSIONS

In the present study, the optimal timing of indocyanine green administration for fluorescent cholangiography during laparoscopic cholecystectomy using the PINPOINT Endoscopic Fluorescence Imaging System was 15 h before surgery.

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

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

A practical guide for the use of indocyanine green and methylene blue in fluorescence-guided abdominal surgery

Near-infrared (NIR) fluorescence imaging is gaining clinical acceptance over the last years and has been used for detection of lymph nodes, several tumor types, vital structures and tissue perfusion. This review focuses on NIR fluorescence imaging with indocyanine green and methylene blue for different clinical applications in abdominal surgery with an emphasis on oncology, based on a systematic literature search. Furthermore, practical information on doses, injection times, and intraoperative use are provided.

Near-infrared fluorescent cholangiography - real-time visualization of the biliary tree during elective laparoscopic cholecystectomy

BACKGROUND

The purpose was to evaluate the efficacy of near-infrared fluorescent cholangiography (FC) in real-time visualization of the biliary tree during elective laparoscopic cholecystectomy.

METHODS

Fifty consecutive elective laparoscopic cholecystectomies were performed with fluorescent cholangiography. FC was performed at three time points: following exposure of Calot's triangle, prior to any dissection; and after partial and complete dissection of Calot's triangle.

RESULTS

The cystic duct (CD) was identified successfully by FC in 43 of 50 patients (86%) and in 45 of 50 patients (90%) before and after Calot's dissection respectively (p > 0.05). The common hepatic duct (CHD) and the common bile duct (CBD) were identified successfully in 12 of 50 patients (24%) and in 33 of 50 patients (66%) before Calot's dissection respectively and in 26 of 50 patients (52%) and in 47 of 50 patients (94%) after complete Calot's dissection (p = 0.007 and p = 0.001, respectively). Significant differences were observed for CBD visualization rate, in relation to BMI after Calot's dissection (p < 0.05) and history of cholecystitis, before Calot's dissection (p = 0.017). No bile duct injuries were reported.

CONCLUSION

Fluorescent cholangiography can be considered as a useful tool for intra-operative visualization of the biliary tree during laparoscopic cholecystectomies.

Optimizing the image of fluorescence cholangiography using ICG: a systematic review and ex vivo experiments

Background

Though often only briefly described in the literature, there are clearly factors that have an influence on the fluorescence intensity, and thereby the usefulness of the technique. This article aims to provide an overview of the factors influencing the fluorescence intensity of fluorescence imaging with Indocyanine green, primarily focussed on NIRF guided cholangiography.

Methods

A systematic search was conducted to gain an overview of currently used methods in NIRF imaging in laparoscopic cholecystectomies. Relevant literature was searched to gain advice on what methods to use. Ex vivo experiments were performed to assess various factors that influence fluorescence intensity and whether the found clinical advices can be confirmed.

Results

ICG is currently the most widely applied fluorescent dye. Optimal ICG concentration lies between 0.00195 and 0.025 mg/ml, and this dose should be given as early as achievable—but maximum 24 h—before surgery. When holding the laparoscope closer and perpendicular to the dye, the signal is most intense. In patients with a higher BMI and/or cholecystitis, fluorescence intensity is lower, but NIRF seems to be more helpful. There are differences between various marketed fluorescence systems. Also, no uniform method to assess fluorescence intensity is available yet.

Conclusions

This study identified and discussed several factors that influence the signal of fluorescence cholangiography. These factors should be taken into account when using NIRF cholangiography. Also, surgeons should be aware of new dyes and clinical systems, in order to benefit most from the potential of NIRF imaging.

Electronic supplementary material

The online version of this article (10.1007/s00464-018-6233-x) contains supplementary material, which is available to authorized users.

A new fluorescence imaging technique for visualizing hepatobiliary structures using sodium fluorescein: result of a preclinical study in a rat model

BACKGROUND

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

METHODS

Sodium fluorescein solution (1 mL to each individual) were administered intravenously to 20 male Sprague-Dawley rats (6 weeks old, 200-250 g), after laparotomy. Whole abdominal organs were observed under blue light (at a wavelength of 440-490 nm) emitted from a commercialized LED curing light.

RESULTS

Immediately after the tracer solution was administered into the circulatory system of the rat, it was possible to visualize the location of the kidneys and the bile duct under blue light emitted from the light source. The liver was vaguely stained green by the tracer, while the ureters were not. After establishing biliary retention via duct clamping in the left lateral segment of the liver, the green color of the segment became distinct by the tracer, which showed vague coloration following release of the clamp.

CONCLUSION

We established the preclinical basis for using blue light fluorescence cholangiography and liver mapping in this study. The clinical feasibility of these techniques during laparoscopic cholecystectomy and hepatectomy remained to be demonstrated.

Near-infrared cholecystocholangiography with direct intragallbladder indocyanine green injection: preliminary clinical results

BACKGROUND

Near-infrared (NIR) fluorescence cholangiography by systemic administration of indocyanine green (ICG) enhances the visualization of the biliary tree anatomy. However, the simultaneous enhancement of liver parenchyma can disturb the visualization of critical details. We herein proposed a new technique of NIR cholecystocholangiography by intragallbladder ICG injection to increase the safety during laparoscopic cholecystectomy.

METHODS

A total of 46 patients scheduled for laparoscopic cholecystectomy for symptomatic lithiasis (n = 21) or cholecystitis (n = 25) were enrolled. A fluorescence cholangiography by direct gallbladder injection of ICG was performed in all cases. Of them, the ICG was injected through a previously placed percutaneous transhepatic gallbladder drainage catheter (n = 18) or by intraoperative, percutaneous needle puncture of the gallbladder (n = 28). Visualization of biliary structures, including the cystic duct (CD), the common bile and hepatic ducts (CBD and CHD), the gallbladder neck, and the Hartmann's pouch (HP), was performed using White Light (served as control modality) and by NIR enhancement.

RESULTS

Cholecystocholangiography provided a significantly higher rate of visualization of the CD in case of cholecystitis with mild adhesions, and an improved visualization of the HP, CBD, and CHD in case of severe inflammation, when compared to White Light observation. There were no benefits of NIR in case of non-inflamed lithiasis.

CONCLUSIONS

Clinical translation of NIR cholecystocholangiography has been successful with a noise-free visualization of biliary anatomy. It can be considered in difficult cases to increase the safety of laparoscopic cholecystectomy.

Optimization of liposomal indocyanine green for imaging of the urinary pathways and a proof of concept in a pig model

BACKGROUND

Iatrogenic ureteral injury is an increasing concern in the laparoscopic era, affecting both patient morbidity and costs. Current techniques enabling intraoperative ureteral identification require invasive procedures or radiations. Our aim was to develop a real-time, non-invasive, radiation-free method to visualize ureters, based on near-infrared (NIR) imaging. For this purpose, we interfered with the biliary excretion pathway of the indocyanine green (ICG) fluorophore by loading it into liposomes, enabling renal excretion. In this work, we studied various parameters influencing ureteral imaging.

METHODS

Fluorescence intensity (FI) of various liposomal ICG sizes and doses were characterized in vitro and subsequently tested in vivo in mice and pigs. Quantification was performed by measuring FI in multiple points and applying the ureteral/retroperitoneum ratio (U/R).

RESULTS

The optimal liposomal ICG loading dose was 20%, for the different liposomes' sizes tested (30, 60, 100 nm). Higher concentration of ICG decreased FI. In vivo, the optimal liposome size for ureteral imaging was 60 nm, which yielded a U/R of 5.2 ± 1.7 (p < 0.001 vs. free ICG). The optimal ICG dose was 8 mg/kg (U/R = 2.1 ± 0.4, p < 0.05 vs. 4 mg/kg). Only urine after liposomal ICG injection had a measurable FI, and not after free ICG injection. Using a NIR-optimized laparoscopic camera, ureters could be effectively imaged in pigs, from 10 min after injection and persisting for at least 90 min. Ureteral peristaltic waves could be clearly identified only after liposomal ICG injection.

CONCLUSIONS

Optimization of liposomal ICG allowed to visualize enhanced ureters in animal models and seems a promising fluorophore engineering, which calls for further developments.

Highly Selective Red-Emitting Fluorescent Probe for Imaging Cancer Cells in Situ by Targeting Pim-1 Kinase

Based on the fact that enzyme-targeting probes are highly sensitive and selective, a novel red-emitting probe (NB-BF) for Pim-1 kinase including three parts, fluorophore (NB), linker, and inhibitor (BF), has been designed for cancer optical imaging. In its free state, NB-BF is folded and the fluorescence quenched by PET between fluorophore and inhibitor both in PBS buffer and in normal cells. Significantly, it emitted strong red fluorescence in Pim-1 overexpressed cancer cells. The specificity of NB-BF for Pim-1 kinase was directly demonstrated by gene silencing analysis. Furthermore, it is the first time to know where Pim-1 kinase mainly distributes at mitochondria with Pearson's correlation factor (R_r) of 0.965 and to provide a fluorescent tool to verify the function of the Pim-1 kinase. More importantly, NB-BF was applied in tissue imaging and preferentially labeled tumors in vivo.

Prospective Evaluation of Precision Multimodal Gallbladder Surgery Navigation: Virtual Reality, Near-infrared Fluorescence, and X-ray-based Intraoperative Cholangiography

OBJECTIVE

We aimed to prospectively evaluate NIR-C, VR-AR, and x-ray intraoperative cholangiography (IOC) during robotic cholecystectomy.

BACKGROUND

Near-infrared cholangiography (NIR-C) provides real-time, radiation-free biliary anatomy enhancement. Three-dimensional virtual reality (VR) biliary anatomy models can be obtained via software manipulation of magnetic resonance cholangiopancreatography, enabling preoperative VR exploration, and intraoperative augmented reality (AR) navigation.

METHODS

Fifty-eight patients were scheduled for cholecystectomy for gallbladder lithiasis. VR surgical planning was performed on virtual models. At anesthesia induction, indocyanine green was injected intravenously. AR navigation was obtained by overlaying the virtual model onto real-time images. Before and after Calot triangle dissection, NIR-C was obtained by turning the camera to NIR mode. Finally, an IOC was performed. The 3 modality performances were evaluated and image quality was assessed with a Likert-scale questionnaire.

RESULTS

The three-dimensional VR planning enabled the identification of 12 anatomical variants in 8 patients, of which only 7 were correctly reported by the radiologists (P = 0.037). A dangerous variant identified at VR induced a "fundus first" approach. The cystic-common bile duct junction was visualized before Calot triangle dissection at VR in 100% of cases, at NIR-C in 98.15%, and in 96.15% at IOC.Mean time to obtain relevant images was shorter with NIR-C versus AR (P = 0.008) and versus IOC (P = 0.00000003). Image quality scores were lower with NIR-C versus AR (P = 0.018) and versus IOC (P < 0.0001).

CONCLUSIONS

This high-tech protocol illustrates the multimodal imaging of biliary anatomy towards precision cholecystectomy. Those visualization techniques could complement to reduce the likelihood of biliary injuries (NCT01881399).

Intraoperative Real-Time Assessment of Liver Function with Near-Infrared Fluorescence Imaging

BACKGROUND

Postoperative liver failure is a serious complication after major hepatectomy, and perioperative prediction of its incidence using current technology is still very difficult. Near-infrared (NIR) fluorescence imaging allows quantitative assessment of the fluorescent signal from indocyanine green (ICG) in regions of interest on the liver surface. This method might offer a new promising modality for evaluating regional liver reserve. However, data are lacking regarding the relationship between liver function and fluorescent signals on the liver surface after intravenous ICG injection. This study was conducted to obtain the data necessary to apply NIR fluorescence imaging as a modality for measuring liver function.

MATERIALS AND METHODS

This study included 16 patients who underwent open hepatopancreatobiliary surgery between March 2011 and March 2012. After laparotomy, ICG was injected intravenously at 2.5 mg/L of liver volume, then the fluorescence intensity (FI) and signal-to-background ratio (SBR) in the lateral segment of the liver were assessed for 15 min. Intraoperative blood samples were also obtained to measure the plasma clearance rate of ICG (ICGK). Correlations between ICGK, liver volume, and SBR, as well as between ICGK, liver volume, and rate of change of FI were analyzed.

RESULTS

The experimental procedure was performed in all 16 patients. The FI of the liver increased rapidly after ICG injection, then became more gradual, reaching a near-plateau after 15 min. A significant correlation was seen between ICGK and the rate of change of FI up to 15 min (|rS| = 0.5725, p < 0.05).

CONCLUSION

This is the first report to show a relationship between liver function and fluorescent signals on the liver surface after intravenous ICG injection. Intraoperative NIR fluorescence imaging with ICG may be useful as a new method for assessing liver function.

The Best Approach for Laparoscopic Fluorescence Cholangiography: Overview of the Literature and Optimization of Dose and Dosing Time

BACKGROUND

Fluorescence cholangiography using indocyanine green (ICG) can enhance orientation of bile duct anatomy during laparoscopic cholecystectomy. To ensure clear discrimination between bile ducts and liver, the fluorescence ratio between both should be sufficient. This ratio is influenced by the ICG dose and timing of fluorescence imaging. We first systematically identified all strategies for fluorescence cholangiography. Second, we aimed to optimize the dose of ICG and dosing time in a prospective clinical trial.

METHODS

PubMed was searched for clinical trials studying fluorescence cholangiography. Furthermore, 28 patients planned to undergo laparoscopic cholecystectomy were divided into 7 groups, receiving different intravenous doses (5 or 10 mg ICG) at different time points (0.5, 2, 4, 6, or 24 hours prior to surgery).

RESULTS

The systematic review revealed 27 trials including 1057 patients. The majority of studies used 2.5 mg administered within 1 hour before imaging. Imaging 3 to 24 hours after ICG administration was never studied. The clinical trial demonstrated that the highest bile duct-to-liver ratio was achieved 3 to 7 hours after administration of 5 mg and 5 to 25 hours after administration of 10 mg ICG. Up to 3 hours after administration of 5 mg and up to 5 hours after administration of 10 mg ICG, the liver was equally or more fluorescent than the cystic duct, resulting in a ratio ≤1.0.

CONCLUSION

This study shows for the first time that the interval between ICG administration and intraoperative fluorescence cholangiography should be extended. Administering 5 mg ICG at least 3 hours before imaging is easy to implement in everyday clinical practice and results in bile duct-to-liver ratios >1.0.

Near-infrared fluorescence laparoscopy of the cystic duct and cystic artery: first experience with two new preclinical dyes in a pig model

Background

Imaging techniques that enhance visualisation of the anatomy may help prevent bile duct injury. Near-Infrared Fluorescence Imaging is such a technique. Previous experiments with ICG have shown that illumination of the extra-hepatic bile ducts is feasible. Yet, there is room for improvement in the visualisation of the target as compared to the background. Experiments with IRDye^® 800CW show promising results. However, this dye is too expensive for routine clinical use. The aim of this study is to test the first applicability of two newly developed preclinical dyes regarding intraoperative imaging of the cystic duct and cystic artery, compared with IRDye^® 800CW.

Methods

Laparoscopic cholecystectomy was performed in three pigs, using a laparoscopic fluorescence imaging system. Each pig received 6 mg of one of the fluorescent dyes (1 mg/mL; IRDye^® 800CW, IRDye^® 800BK or IRDye^® 800NOS) by intravenous injection. Intraoperative recognition of the biliary system and cystic artery was registered at set time points. All procedures were digitally recorded, and the target to background ratio (TBR) was determined to assess the fluorescence signal.

Results

With all three fluorescent dyes, the cystic artery was directly visualised. For the visualisation of the cystic duct, 15, 34 and 30 min were needed using IRDye^® 800BK, IRDye^® 800NOS and IRDye^® 800CW, respectively. The maximum TBR of the cystic duct was the highest with IRDye^® 800NOS (4.20) after 36 min, compared to 2.45 for IRDye^® 800BK and 2.15 for IRDye^® 800CW, both after 45 min. There were no adverse events.

Conclusion

IRDye^® 800BK and IRDye^® 800NOS seem to be good alternatives for IRDye^® 800CW for the visualisation of the cystic duct and cystic artery in pigs.

Fluorescent Imaging With Indocyanine Green During Laparoscopic Cholecystectomy in Patients at Increased Risk of Bile Duct Injury

BACKGROUND

Although rare, injury to the common bile duct (CBD) during laparoscopic cholecystectomy (LC) can be reduced by better intraoperative visualization of the cystic duct (CD) and CBD. The aim of this study was to establish the efficacy of early visualization of the CD and the added value of CBD identification, using near-infrared (NIR) light and the fluorescent agent indocyanine green (ICG), in patients at increased risk of bile duct injury.

MATERIALS AND METHODS

Patients diagnosed with complicated cholecystitis and scheduled for LC were included. The CBD and CD were visualized with NIR light before and during dissection of the liver hilus and at critical view of safety (CVS).

RESULTS

Of the 20 patients originally included, 2 were later excluded due to conversion. In 6 of 18 patients, the CD was visualized early during dissection and prior to imaging with conventional white light. The CBD was additionally visualized with ICG-NIR in 7 of 18 patients. In 1 patient, conversion was prevented due to detection of the CD and CBD with ICG-NIR.

CONCLUSIONS

Early visualization of the CD or additional identification of the CBD using ICG-NIR in patients with complicated cholecystolithiasis can be helpful in preventing CBD injury. Future studies should attempt to establish the optimal dosage and time frame for ICG administration and bile duct visualization with respect to different gallbladder pathologies.

Indocyanine green fluorescence imaging in hepatobiliary surgery

Indocyanine green (ICG) is a fluorescent dye that has been widely used for fluorescence imaging during hepatobiliary surgery. ICG is injected intravenously, selectively taken up by the liver, and then secreted into the bile. The catabolism and fluorescence properties of ICG permit a wide range of visualization methods in hepatobiliary surgery. We have characterized the applications of ICG during hepatobiliary surgery into: 1) liver mapping, 2) cholangiography, 3) tumor visualization, and 4) partial liver graft evaluation. In this literature review, we summarize the current understanding of ICG use during hepatobiliary surgery. Intra-operative ICG fluorescence imaging is a safe, simple, and feasible method that improves the visualization of hepatobiliary anatomy and liver tumors. Intravenous administration of ICG is not toxic and avoids the drawbacks of conventional imaging. In addition, it reduces post-operative complications without any known side effects. ICG fluorescence imaging provides a safe and reliable contrast for extra-hepatic cholangiography when detecting intra-hepatic bile leakage following liver resection. In addition, liver tumors can be visualized and well-differentiated hepatocellular carcinoma tumors can be accurately identified. Moreover, vascular reconstruction and outflow can be evaluated following partial liver transplantation. However, since tissue penetration is limited to 5-10mm, deeper tissue cannot be visualized using this method. Many instances of false positive or negative results have been reported, therefore further characterization is required.

EpCAM as multi-tumour target for near-infrared fluorescence guided surgery

Background

Evaluation of resection margins during cancer surgery can be challenging, often resulting in incomplete tumour removal. Fluorescence-guided surgery (FGS) aims to aid the surgeon to visualize tumours and resection margins during surgery. FGS relies on a clinically applicable imaging system in combination with a specific tumour-targeting contrast agent. In this study EpCAM (epithelial cell adhesion molecule) is evaluated as target for FGS in combination with the novel Artemis imaging system.

Methods

The NIR fluorophore IRDye800CW was conjugated to the well-established EpCAM specific monoclonal antibody 323/A3 and an isotype IgG1 as control. The anti-EpCAM/800CW conjugate was stable in serum and showed preserved binding capacity as evaluated on EpCAM positive and negative cell lines, using flow cytometry and cell-based plate assays. Four clinically relevant orthotopic tumour models, i.e. colorectal cancer, breast cancer, head and neck cancer, and peritonitis carcinomatosa, were used to evaluate the performance of the anti-EpCAM agent with the clinically validated Artemis imaging system. The Pearl Impulse small animal imaging system was used as reference. The specificity of the NIRF signal was confirmed using bioluminescence imaging and green-fluorescent protein.

Results

All tumour types could clearly be delineated and resected 72 h after injection of the imaging agent. Using NIRF imaging millimetre sized tumour nodules were detected that were invisible for the naked eye. Fluorescence microscopy demonstrated the distribution and tumour specificity of the anti-EpCAM agent.

Conclusions

This study shows the potential of an EpCAM specific NIR-fluorescent agent in combination with a clinically validated intraoperative imaging system to visualize various tumours during surgery.

Biliary tract visualization using near-infrared imaging with indocyanine green during laparoscopic cholecystectomy: results of a systematic review

Background

Near-infrared imaging with indocyanine green (ICG) has been extensively investigated during laparoscopic cholecystectomy (LC). However, methods vary between studies, especially regarding patient selection, dosage and timing. The aim of this systematic review was to evaluate the potential of the near-infrared imaging technique with ICG to identify biliary structures during LC.

Methods

A comprehensive systematic literature search was performed. Prospective trials examining the use of ICG during LC were included. Primary outcome was biliary tract visualization. Risk of bias was assessed using ROBINS-I. Secondly, a meta-analysis was performed comparing ICG to intraoperative cholangiography (IOC) for identification of biliary structures. GRADE was used to assess the quality of the evidence.

Results

Nineteen studies were included. Based upon the pooled data from 13 studies, cystic duct (Lusch et al. in J Endourol 28:261–266, 2014) visualization was 86.5% (95% CI 71.2–96.6%) prior to dissection of Calot’s triangle with a 2.5-mg dosage of ICG and 96.5% (95% CI 93.9–98.4%) after dissection. The results were not appreciably different when the dosage was based upon bodyweight. There is moderate quality evidence that the CD is more frequently visualized using ICG than IOC (RR 1.16; 95% CI 1.00–1.35); however, this difference was not statistically significant.

Conclusion

This systematic review provides equal results for biliary tract visualization with near-infrared imaging with ICG during LC compared to IOC. Near-infrared imaging with ICG has the potential to replace IOC for biliary mapping. However, methods of near-infrared imaging with ICG vary. Future research is necessary for optimization and standardization of the near-infrared ICG technique.

Electronic supplementary material

The online version of this article (doi:10.1007/s00464-016-5318-7) contains supplementary material, which is available to authorized users.

A Bright Future for Precision Medicine: Advances in Fluorescent Chemical Probe Design and Their Clinical Application

The Precision Medicine Initiative aims to use advances in basic and clinical research to develop therapeutics that selectively target and kill cancer cells. Under the same doctrine of precision medicine, there is an equally important need to visualize these diseased cells to enable diagnosis, facilitate surgical resection, and monitor therapeutic response. Therefore, there is a great opportunity for chemists to develop chemically tractable probes that can image cancer in vivo. This review focuses on recent advances in the development of optical probes, as well as their current and future applications in the clinical management of cancer. The progress in probe development described here suggests that optical imaging is an important and rapidly developing field of study that encourages continued collaboration among chemists, biologists, and clinicians to further refine these tools for interventional surgical imaging, as well as for diagnostic and therapeutic applications.

Near-infrared cholecysto-cholangiography with indocyanine green may secure cholecystectomy in difficult clinical situations: proof of the concept in a porcine model

BACKGROUND

Biliary injuries remain a major concern in laparoscopic cholecystectomy. New intraoperative guidance modalities, including near-infrared fluorescence cholangiography, are under evaluation. Initial results showed limitations in visualizing the biliary tree in specific clinical situations. The aim of this study was to examine the feasibility and potentiality of fluorescence cholecysto-cholangiography performed with a direct injection of indocyanine green (ICG) in the gallbladder and to compare it to systemic injection in such situations.

MATERIALS AND METHODS

Seven pigs were included in this non-survival study. In two pigs, the gallbladder was punctured by a percutaneous needle, and 1 mL of ICG in different concentrations (0.001, 0.01, 0.1, and 1 mg/mL) was sequentially injected. Visibility and pattern of the fluorescent signal around Calot's triangle were examined and compared with those of two control pigs receiving 2.5 mg of intravenous ICG, 30 min prior to the operation. Different scenarios of cholecystitis were modeled using an injection of a mixture of blood and agarose gel around Calot's triangle area in the remaining three pigs, and the applicability of direct intragallbladder injection methods was evaluated.

RESULTS

The fluorescent signal was identified immediately after intragallbladder injection, and the cystic duct became visible by 0.1 and 1 mg/mL of ICG. The whole cystic duct and the infundibulum of the gallbladder were clearly enhanced by intragallbladder ICG injection, but not by systemic injection. In the cholecystitis models, the cystic duct could be identified only after partial dissection, and fluorescence visualization of the gallbladder infundibulum provided crucial information to find the correct starting point of dissection.

CONCLUSIONS

Fluorescence cholecysto-cholangiography through direct intragallbladder ICG injection could rapidly provide an adequate visualization of gallbladder neck and cystic duct and might be a valid option to increase the safety of cholecystectomy in case of cholecystitis.