Current Trends and Emerging Future of Indocyanine Green Usage in Surgery and Oncology: An Update

Development of a plant-based surgical training model for fluorescence-guided cancer surgery

BACKGROUND

Fluorescence-guided surgery (FGS) can help surgeons to discriminate tumor tissue from adjacent normal tissues using fluorescent tracers.

METHODS

We developed a surgical training model, manufactured using sustainable vegetable organic material with indocyanine green (ICG)-containing "tumor." Surgeons evaluated the model with both the closed-field and endoscopic fluorescence imaging devices and assessed its efficacy to identify residual tumor after enucleation using electrocautery.

RESULTS

Strong correlations of fluorescence were obtained at all working distance (3, 5, 7, and 10 cm), showing the robustness of fluorescence signal for the closed-field and endoscopic fluorescence imaging devices. The higher fluorescence signals were obtained in the wound bed in the closed-field fluorescence imaging device and the residual tumor could be clearly identified by fluorescence endoscopy.

CONCLUSIONS

Our FGS training model may provide experience for surgeons unfamiliar with optical surgery and subsequent tissue interactions. The model seemed particularly helpful in teaching surgeons the principles of FGS.

Treatment of Aphthous Ulcers with Photodynamic Therapy: A Randomized Controlled Clinical Study

BACKGROUND

This study aims to assess whether photodynamic therapy (PDT) offers a clinically effective alternative for treating oral aphthous ulcers, contributing to the ongoing quest for methods to expedite their treatment process amidst the limited understanding of their etiology.

MATERIALS AND METHOD

The study involved thirty volunteers with aphthous ulcers, split equally between a control group and a PDT group. Patients in the PDT group received laser treatment using Indocyanine green upon admission, while the control group received no intervention. Lesion diameter was measured at presentation and on the 3rd, 5th, and 7th days for all patients, with wound healing assessed on the 7th day. Additionally, pain levels were evaluated using the Visual Analog Scale (VAS) preoperatively and on the 1st, 3rd, 5th, and 7th days for the PDT group, and on the corresponding days for the control group.

RESULTS

Lesion diameters in the PDT group showed a significant reduction over time (p=0.001), particularly from preoperative to final measurements. The control group also exhibited a decrease, albeit slower (p=0.001). The 7th-day healing scores favored the PDT group significantly (p=0.012). VAS scores in the PDT group decreased significantly over time (p=0.001), indicating pain reduction. A similar trend was observed in the control group, albeit slower. Between-group differences in healing data and pain data were statistically significant.

CONCLUSION

PDT proves effective in reducing aphthous ulcer diameters and pain intensity, facilitating faster healing than the control group. These results advocate for PDT as a viable treatment option for aphthous lesions.

Imaging guided adrenalectomy with Indocyanine green fluorescence in a dog with a pheochromocytoma

IMPORTANCE

This case report presents the successful surgical removal of a pheochromocytoma in a dog using indocyanine green (ICG) fluorescence imaging.

CASE PRESENTATION

A 10-year-old, 6.87 kg, spayed female poodle was referred for an abdominal mass and eight episodes of vomiting. Computed tomography revealed masses in the spleen and left adrenal gland. Based on the plasma normetanephrine levels, the patient was diagnosed with pheochromocytoma. Subsequently, a total splenectomy and left adrenalectomy were performed. A dose of 5 mg/kg ICG was administered intravenously 24 h prior to surgery. Using ICG allowed visualization of tumor margins, aiding in complete resection and minimizing anesthesia-related risks.

CONCLUSIONS AND RELEVANCE

No evidence of recurrence or metastasis has been observed for 12 months. To our knowledge, this is the first report of the surgical removal of a pheochromocytoma using intraoperative ICG imaging in veterinary medicine. This case highlights the efficacy of ICG fluorescence imaging as a valuable tool for the surgical management of adrenal tumors in veterinary medicine.

Semiquantitative Tissue Perfusion Assessment Using Indocyanine Green in Complex Open Urethral Reconstruction

OBJECTIVE

Current assessment of critical tissue in genitourinary reconstruction, including graft beds and tissue flaps, primarily relies upon qualitative visual and tactile assessment by experienced surgeons. Here we explore the feasibility of using intravenous indocyanine green (ICG) for semiquantitative assessment of perfusion in complex open urethral reconstruction.

METHODS

A standardized protocol for intravenous use of ICG and near-infrared fluorescence was established. Black and white mode was used for qualitative assessment of perfusion based on signal brightness. Quantitative perfusion mode was used to assess relative perfusion to tissue of interest compared to a control area with similar tissue type outside of the studied area. Real-time perfusion was visualized as percentage of perfusion relative to control.

RESULTS

In case 1, the graft bed was assessed during dorsal onlay graft substitution urethroplasty. Perfusion to graft bed was compared to that of erectile bodies proximally. A proposed perfusion cutoff of 60% was noted to correlate with clinical judgment of graft bed quality. In case 2, tissue perfusion of Blandy flap in perineal urethrostomy was assessed before and after mobilization. A cutoff of 40% was proposed based on existing flap-based reconstruction literature with the goal to tailor flap and ultimately avoid tissue ischemia and necrosis. In case 3, in a complex staged substitution urethroplasty after hypospadias repair, the use of ICG facilitated a limited excision and shorter graft inlay in this staged reconstruction.

CONCLUSION

The application of near-infrared fluorescence tools in open genitourinary reconstruction has the potential to advance quantitative assessment of graft, flaps, and other critical tissue planes, and help establish meaningful perfusion threshold and correlate with clinical outcomes.

Current applications of indocyanine green (ICG) in abdominal, gynecologic and urologic surgery: a meta-review and quality analysis with use of the AMSTAR 2 instrument

BACKGROUND

Indocyanine green (ICG) is an injectable fluorochrome that has recently gained popularity as a means of assisting intraoperative visualization during laparoscopic and robotic surgery. Many systematic reviews and meta-analyses have been published. We conducted a meta-review to synthesize the findings of these studies.

METHODS

PubMed and Embase were searched to identify systematic reviews and meta-analyses coping with the uses of ICG in abdominal operations, including Metabolic Bariatric Surgery, Cholecystectomy, Colorectal, Esophageal, Gastric, Hepato-Pancreato-Biliary, Obstetrics and Gynecology (OG), Pediatric Surgery, Surgical Oncology, Urology, (abdominal) Vascular Surgery, Adrenal and Splenic Surgery, and Interdisciplinary tasks, until September 2023. We submitted the retrieved meta-analyses to qualitative analysis based on the AMSTAR 2 instrument.

RESULTS

We identified 116 studies, 41 systematic reviews (SRs) and 75 meta-analyses (MAs), spanning 2013-2023. The most thoroughly investigated (sub)specialties were Colorectal (6 SRs, 25 MAs), OG (9 SRs, 15 MAs), and HPB (4 SRs, 12 MAs). Interestingly, there was high heterogeneity regarding the administered ICG doses, routes, and timing. The use of ICG offered a clear benefit regarding anastomotic leak prevention, particularly after colorectal and esophageal surgery. There was no clear benefit regarding sentinel node detection after OG. According to the AMSTAR 2 tool, most meta-analyses ranked as "critically low" (34.7%) or "low" (58.7%) quality. There were only five meta-analyses (6.7%) that qualified as "moderate" quality, whereas there were no "high" quality reviews.

CONCLUSIONS

Regardless of the abundance of pertinent literature and reviews, surgeons should be cautious when interpreting their results on ICG use in abdominal surgery. Future reviews should focus on ensuring methodological vigor; establishing clear protocols of ICG dose, route of administration, and timing; and improving reporting quality. Other sources of data (e.g., registries) and novel methods of data analysis (e.g., machine learning) might also contribute to an enhanced role of ICG as a decision-making tool in surgery.

Safety and effectiveness of indocyanine green fluorescence imaging-guided laparoscopic hepatectomy for hepatic tumor: a systematic review and meta-analysis

Introduction

Previous clinical investigations have reported inconsistent findings regarding the feasibility of utilizing indocyanine green fluorescence imaging (ICGFI) in laparoscopic liver tumor removal. This meta-analysis aims to comprehensively evaluate the safety and effectiveness of ICGFI in laparoscopic hepatectomy (LH).

Methods

A systematic search of pertinent clinical studies published before January 30th, 2023 was conducted in databases including PubMed, Embase, Cochrane, and Web of Science. The search strategy encompassed key terms such as "indocyanine green fluorescence," "ICG fluorescence," "laparoscopic hepatectomy," "hepatectomies," "liver Neoplasms," "hepatic cancer," and "liver tumor." Additionally, we scrutinized the reference lists of included articles to identify supplementary studies. we assessed the quality of the incorporated studies and extracted clinical data. Meta-analysis was performed using STATA v.17.0 software. Either a fixed-effects or a random-effects model was employed to compute combined effect sizes, accompanied by 95% confidence intervals (CIs), based on varying levels of heterogeneity.

Results

This meta-analysis encompassed eleven retrospective cohort studies, involving 959 patients in total. Our findings revealed that, in comparison to conventional laparoscopic hepatectomy, patients receiving ICGFI-guided LH exhibited a higher R0 resection rate (OR: 3.96, 95% CI: 1.28, 12.25, I2 = 0.00%, P = 0.778) and a diminished incidence of intraoperative blood transfusion (OR: 0.42, 95% CI: 0.22, 0.81, I 2 = 51.1%, P = 0.056). Additionally, they experienced shorter postoperative hospital stays (WMD: -1.07, 95% CI: -2.00, -0.14, I 2 = 85.1%, P = 0.000). No statistically significant differences emerged between patients receiving ICGFI-guided LH vs. those undergoing conventional LH in terms of minimal margin width and postoperative complications.

Conclusion

ICGFI-guided LH demonstrates marked superiority over conventional laparoscopic liver tumor resection in achieving R0 resection and reducing intraoperative blood transfusion rates. This technique appears to hold substantial promise. Nonetheless, further studies are needed to explore potential long-term benefits associated with patients undergoing ICGFI-guided LH.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD 42023398195.

Efficacy and safety of near-infrared fluorescence identification of the thoracic duct during left lateral neck dissection

BACKGROUND

Thoracic duct leaks occur in up to 5% of left lateral neck dissections. No one imaging modality is routinely used to identify the thoracic duct intraoperatively. The goal of our study was to evaluate the efficacy and safety of indocyanine green lymphangiography for intraoperative identification of the thoracic duct compared to traditional methods using ambient and evaluate the optimal timing of indocyanine green administration.

METHODS

We enrolled all patients who underwent left lateral neck dissection at our institution from 2018 to 2022 in this prospective clinical trial. After indocyanine green injection into the dorsum of the foot, we performed intraoperative imaging was performed with a near-infrared fluorescence camera. We reported the data using descriptive statistics.

RESULTS

Of the 42 patients we enrolled, 14 had prior neck surgery, and 3 had prior external beam radiation. We visualized the thoracic duct with ambient light in 48% of patients and with near-infrared fluorescence visualization in 64%. In 17% of patients, we could identify the thoracic duct only using near-infrared fluorescence visualization, which occurred within 3 minutes of injection, and were required to re-dose 5 patients. We visualized the thoracic duct with near-infrared fluorescence in all patients with prior neck radiation and 77% of patients with prior neck surgery. One adverse reaction occurred (hypotension), and 5 intraoperative thoracic duct injuries occurred that were ligated. There with no chylous fistulas postoperatively.

CONCLUSION

This trial demonstrates that near-infrared fluorescence identification of the thoracic duct is feasible and safe with indocyanine green lymphangiography, even in patients with prior neck surgery or radiation.

Suppression of subgingival bacteria by antimicrobial photodynamic therapy using transgingival irradiation: A randomized clinical trial

BACKGROUND

Antimicrobial photodynamic therapy (aPDT) is an effective method for eradicating bacteria in periodontal therapy. Standard aPDT requires the insertion of a laser tip into a periodontal pocket, in which the direction of irradiation is limited. Therefore, we devised an aPDT method that uses a transgingival near-infrared wavelength and indocyanine green-encapsulated and chitosan-coated nanoparticles as a photosensitizer.

METHODS

Forty patients undergoing supportive periodontal therapy, who had a single root tooth with a pocket of 5 mm or deeper, were used as subjects. In the test group, aPDT was performed by laser irradiation from outside the gingiva using photosensitizer nanoparticles. In the control group, pseudo aPDT without photosensitizer was performed by transgingival irradiation. Subgingival plaque was sampled from inside the pocket before, immediately after, and 1 week after treatment, and evaluated by colony counting and real-time polymerase chain reaction.

RESULTS

There were no significant differences in age, sex, periodontal pocket depth, and bleeding on probing between the test and control groups. Compared with the colony count before treatment, the count in the test group was significantly reduced immediately after treatment. The number of patients with colony reduction to ≤50% and ≤10% was significantly higher in the test group than in the control group. None of the participants reported pain, although one participant reported discomfort.

CONCLUSION

As a bacterial control method for residual pockets in patients undergoing supportive periodontal therapy, transgingival aPDT is a promising treatment strategy that is not generally accompanied by pain or discomfort.

Impact of Indocyanine Green Fluorescence Imaging on Lymphadenectomy Quality During Laparoscopic Distal Gastrectomy for Gastric Cancer (Greeneye): An Adaptative, Phase 2, Clinical Trial

BACKGROUND

Indocyanine green (ICG)-guided lymphadenectomy using near-infrared visualization (NIR) may increase nodal yield during gastrectomy. The purpose of this study was to evaluate the clinical benefit of NIR visualization on the quality of D2 lymphadenectomy during laparoscopic distal gastrectomy.

METHODS

This single-arm, open-label, Simon's two-stage, adaptive, phase 2 trial included patients who underwent laparoscopic distal gastrectomy for gastric adenocarcinoma. Endoscopic peritumoral injection of ICG was performed 24 ± 6 h before surgery. Intraoperatively, after standard D2 lymphadenectomy and specimen extraction, NIR was used for eventual completion lymphadenectomy. The primary endpoint was clinical benefit of NIR (i.e., at least one additional harvested station containing lymph nodes, with negative points for every harvested station with no lymph nodes at final pathology).

RESULTS

We enrolled 18 patients (61% female, median age 69 years). With NIR, an extra 23 stations were harvested: 9 contained no lymph nodes, 12 contained nonmetastatic lymph nodes, and 2 contained metastatic lymph nodes. The most commonly visualized station with NIR were station 6 (8 patients) and 1 (4 patients). The total number of harvested nodes per patient was 32 (interquartile range [IQR] 26-41), with a median of 1 (IQR 0-1) additional lymph node after NIR. Overall, seven (39%) patients had a clinical benefit from NIR, of which two (11%) had one metastatic lymph node harvested with NIR.

CONCLUSIONS

NIR visualization improves the quality of D2 lymphadenectomy in distal gastrectomy for gastric cancer. Considering the limited improve in the number of harvested lymph nodes, its real oncological benefit is still questionable.

The Role of Colour Segmented Fluorescence (CSF) Mode and Same-day Administration of Low-dose Indocyanine Green in Liver Surgery: Our Initial Experience : Indocyanine Green Fluorescence Guided Resection of Liver Tumours

Indocyanine green (ICG) fluorescence image guidance (I-FIGS) is increasingly used in liver surgery. Several regimens have been described regarding the optimum timing and dose of administration. This study presents our early experience with utilising monochromatic Colour Segmented Fluorescence (CSF)-mode and same-day administration of low-dose-ICG in the resection of liver tumours. Between November 2020 and March 2022, I-FIGS was used in 15 patients with suspected liver tumours. ICG was administered intravenously at 0.02 to 0.05 mg/kg dose 2-3 h before surgery. ICG camera was switched to CSF-grey-scale mode to visualise the tumour and to avoid the interference of the green background liver. Using the SPY-CSF mode, the image was scaled to near-infra-red (NIR) fluorescence intensity to accurately identify the tumours and resection margins. Fifteen patients (eight males) with a median age of 71 years (range: 36-86) underwent I-FIGS. Of these, 67% underwent laparoscopic liver surgery, 78% had non-anatomical resections, and 33% underwent redo liver surgery. The mean tumour size was 40.6 mm (SD+/-41 mm). The median number of tumours was two (1-7). All colorectal liver metastases (CRLM) had a signet ring appearance. Hepatocellular carcinomas (HCC) showed partial fluorescence. Tumours were well/moderately differentiated, with CRLM in 86% and HCC in two patients. The R0 resection rate was 72%. In our experience, low-dose-ICG administered at least 2-3 h before surgery can identify liver tumours and their margins in CSF-grey-scale mode. Further research is needed to evaluate its role in reducing R1 resection rates and surgical outcomes.

European Association for Endoscopic Surgery (EAES) consensus on Indocyanine Green (ICG) fluorescence-guided surgery

BACKGROUND

In recent years, the use of Indocyanine Green (ICG) fluorescence-guided surgery during open and laparoscopic procedures has exponentially expanded across various clinical settings. The European Association of Endoscopic Surgery (EAES) initiated a consensus development conference on this topic with the aim of creating evidence-based statements and recommendations for the surgical community.

METHODS

An expert panel of surgeons has been selected and invited to participate to this project. Systematic reviews of the PubMed, Embase and Cochrane libraries were performed to identify evidence on potential benefits of ICG fluorescence-guided surgery on clinical practice and patient outcomes. Statements and recommendations were prepared and unanimously agreed by the panel; they were then submitted to all EAES members through a two-rounds online survey and results presented at the EAES annual congress, Barcelona, November 2021.

RESULTS

A total of 18,273 abstracts were screened with 117 articles included. 22 statements and 16 recommendations were generated and approved. In some areas, such as the use of ICG fluorescence-guided surgery during laparoscopic cholecystectomy, the perfusion assessment in colorectal surgery and the search for the sentinel lymph nodes in gynaecological malignancies, the large number of evidences in literature has allowed us to strongly recommend the use of ICG for a better anatomical definition and a reduction in post-operative complications.

CONCLUSIONS

Overall, from the systematic literature review performed by the experts panel and the survey extended to all EAES members, ICG fluorescence-guided surgery could be considered a safe and effective technology. Future robust clinical research is required to specifically validate multiple organ-specific applications and the potential benefits of this technique on clinical outcomes.

Indocyanine green derived carbon dots with significantly enhanced properties for efficient photothermal therapy

A simple yet effective strategy to enhance the properties of traditional dye indocyanine green (ICG) in all aspects was proposed and demonstrated. Specifically, indocyanine green-derived carbon dots (ICGCDs) were synthesized from ICG via a simple hydrothermal treatment. The ICGCDs exhibited significantly enhanced thermal stability and anti-photobleaching compared to ICG. Furthermore, their photothermal properties were also notably strengthened, in which a wider functional pH range, 50% improvement in photothermal conversion efficiency and superior photothermal cyclability were achieved. Thanks to these superior properties, ICGCDs were demonstrated as efficient NIR bioimaging and photothermal agents in both in vitro and in vivo experiments. Most excitingly, the strategy demonstrated in this study is likely to have broad applications in other systems.

Optimizing Axial and Peripheral Substitutions in Si-Centered Naphthalocyanine Dyes for Enhancing Aqueous Solubility and Photoacoustic Signal Intensity

Photoacoustic imaging using external contrast agents is emerging as a powerful modality for real-time molecular imaging of deep-seated tumors. There are several chromophores, such as indocyanine green and IRDye800, that can potentially be used for photoacoustic imaging; however, their use is limited due to several drawbacks, particularly photostability. There is, therefore, an urgent need to design agents to enhance contrast in photoacoustic imaging. Naphthalocyanine dyes have been demonstrated for their use as photoacoustic contrast agents; however, their low solubility in aqueous solvents and high aggregation propensity limit their application. In this study, we report the synthesis and characterization of silicon-centered naphthalocyanine dyes with high aqueous solubility and near infra-red (NIR) absorption in the range of 850-920 nm which make them ideal candidates for photoacoustic imaging. A series of Silicon-centered naphthalocyanine dyes were developed with varying axial and peripheral substitutions, all in an attempt to enhance their aqueous solubility and improve photophysical properties. We demonstrate that axial incorporation of charged ammonium mesylate group enhances water solubility. Moreover, the incorporation of peripheral 2-methoxyethoxy groups at the α-position modulates the electronic properties by altering the π-electron delocalization and enhancing photoacoustic signal amplitude. In addition, all the dyes were synthesized to incorporate an N-hydroxysuccinimidyl group to enable further bioconjugation. In summary, we report the synthesis of water-soluble silicon-centered naphthalocyanine dyes with a high photoacoustic signal amplitude that can potentially be used as contrast agents for molecular photoacoustic imaging.

Delphi survey of intercontinental experts to identify areas of consensus on the use of indocyanine green angiography for tissue perfusion assessment during plastic and reconstructive surgery

BACKGROUND

In recent years, indocyanine green angiography (ICG-A) has been used increasingly to assist tissue perfusion assessments during plastic and reconstructive surgery procedures, but no guidelines exist regarding its use. We sought to identify areas of consensus and non-consensus among international experts on the use of ICG-A for tissue-perfusion assessments during plastic and reconstructive surgery.

METHODS

A two-round, online Delphi survey was conducted of 22 international experts from four continents asking them to vote on 79 statements divided into five modules: module 1 = patient preparation and contraindications (n = 11 statements); module 2 = ICG administration and camera settings (n = 17); module 3 = other factors impacting perfusion assessments (n = 10); module 4 = specific indications, including trauma debridement (n = 9), mastectomy skin flaps (n = 6), and free flap reconstruction (n = 8); and module 5 = general advantages and disadvantages, training, insurance coverage issues, and future directions (n = 18). Consensus was defined as ≥70% inter-voter agreement.

RESULTS

Consensus was reached on 73/79 statements, including the overall value, advantages, and limitations of ICG-A in numerous surgical settings; also, on the dose (0.05 mg/kg) and timing of ICG administration (∼20-60 seconds preassessment) and best camera angle (61-90^o) and target-to-tissue distance (20-30 cm). However, consensus also was reached that camera angle and distance can vary, depending on the make of camera, and that further research is necessary to technically optimize this imaging tool. The experts also agreed that ambient light, patient body temperature, and vasopressor use impact perfusion assessments.

CONCLUSION

ICG-A aids perfusion assessments during plastic and reconstructive surgery and should no longer be considered experimental. It has become an important surgical tool.

Use of fluorescence imaging and indocyanine green during laparoscopic cholecystectomy: Results of an international Delphi survey

BACKGROUND

Published empirical data have increasingly suggested that using near-infrared fluorescence cholangiography during laparoscopic cholecystectomy markedly increases biliary anatomy visualization. The technology is rapidly evolving, and different equipment and doses may be used. We aimed to identify areas of consensus and nonconsensus in the use of incisionless near-infrared fluorescent cholangiography during laparoscopic cholecystectomy.

METHODS

A 2-round Delphi survey was conducted among 28 international experts in minimally invasive surgery and near-infrared fluorescent cholangiography in 2020, during which respondents voted on 62 statements on patient preparation and contraindications (n = 12); on indocyanine green administration (n = 14); on potential advantages and uses of near-infrared fluorescent cholangiography (n = 18); comparing near-infrared fluorescent cholangiography with intraoperative x-ray cholangiography (n = 7); and on potential disadvantages of and required training for near-infrared fluorescent cholangiography (n = 11).

RESULTS

Expert consensus strongly supports near-infrared fluorescent cholangiography superiority over white light for the visualization of biliary structures and reduction of laparoscopic cholecystectomy risks. It also offers other advantages like enhancing anatomic visualization in obese patients and those with moderate to severe inflammation. Regarding indocyanine green administration, consensus was reached that dosing should be on a milligrams/kilogram basis, rather than as an absolute dose, and that doses >0.05 mg/kg are necessary. Although there is no consensus on the optimum preoperative timing of indocyanine green injections, the majority of participants consider it important to administer indocyanine green at least 45 minutes before the procedure to decrease the light intensity of the liver.

CONCLUSION

Near-infrared fluorescent cholangiography experts strongly agree on its effectiveness and safety during laparoscopic cholecystectomy and that it should be used routinely, but further research is necessary to establish optimum timing and doses for indocyanine green.

Use of fluorescence imaging during lymphatic surgery: A Delphi survey of experts worldwide

BACKGROUND

Fluorescence imaging with indocyanine green is increasingly used during lymphedema patient management. However, to date, no guidelines exist on when it should and should not be used or how it should be performed. Our objective was to have an international panel of experts identify areas of consensus and nonconsensus in current attitudes and practices in fluorescence imaging with indocyanine green use during lymphedema surgery patient management.

METHODS

A 2-round Delphi study was conducted involving 18 experts in the use of fluorescence imaging during lymphatic surgery, all asked to vote on 49 statements on patient preparation and contraindications (n = 7 statements), indocyanine green dosing and administration (n = 10), fluorescence imaging uses and potential advantages (n = 16), and potential disadvantages and training needs (n = 16).

RESULTS

Consensus ultimately was reached on 40/49 statements, including consistent consensus regarding the value of fluorescence imaging with indocyanine green in almost all facets of lymphedema patient management, including early detection, assessing disease extent, preoperative work-up, surgical planning, intraoperative guidance, monitoring short- and longer-term outcomes, quality control, and resident training. All experts felt it was very safe, while 94% felt it should be part of routine care and that indocyanine green was superior to colored dyes and ultrasound. Nonetheless, there also was consensus that limited high-quality evidence remains a barrier to its widespread use and that patients should still be provided with specific information and asked to sign specific consent for both fluorescence imaging and indocyanine green.

CONCLUSION

Fluorescence imaging with or without indocyanine green appears to have several roles in lymphedema prevention, diagnosis, assessment, and treatment.

Indocyanine green fluorescence imaging improves the assessment of blood supply of interposition jejunum

OBJECTIVES

The blood supply of the transposed jejunum was assessed by ICG fluorescence imaging in jejunal interposition, and the correlation with anastomotic leakage or transposed jejunal necrosis was analyzed, aim to explore the value of the application ICG fluorescence imaging technology.

METHODS

84 esophageal reconstructions with jejunal interposition without supercharging were retrospectively analyzed. Intraoperatively, the blood supply of transposed jejunal was observed using ICG fluorescence endoscopy. ROC curve of T1/2 was constructed to calculate the corresponding T1/2max value of the region where the transposed jejunal want to be anastomosed with esophageal stump, the relationship between T1/2max value and anastomotic leakage or transposed jejunal necrosis was analyzed.

RESULTS

The occurrence of anastomotic leakage and transposed jejunal necrosis was 9.5%, In the ROC curve, the maximum value of the Youden index was 0.691, the T1/2max value was 5.35 s. When T1/2max value > 5.35 s correspondingly, the probability of anastomotic leakage or transposition jejunal necrosis was 33.3% (7/21); when T1/2max value ≤ 5.35 s, the probability of anastomotic leakage or transposition jejunal necrosis was 1.6% (1/63). The difference between the two groups was statistically significant (P < 0.05).

CONCLUSION

ICG fluorescent imaging can effectively assess the blood supply of transposed jejunum. When T1/2max > 5.35, the possibility of the incidence rate of anastomotic leakage or transposed jejunum necrosis increases, this will remind the operators to take corresponding remedial measures during operation.

Validation of a surgical training model containing indocyanine green for near‐infrared fluorescence imaging

Objective

To determine the efficacy of a surgical training model for fluorescence‐guided cancer surgery and validate its utility to detect any residual tumors after tumor resection using electrocautery.

Methods

We developed surgical training models containing indocyanine green (ICG) for near‐infrared (NIR) fluorescence imaging using a root vegetable organic material (konjac). After the fluorescence assessment for the models, the surgical simulation for fluorescence‐guided cancer surgery using electrocautery was performed. ICG‐containing tumors were divided into two surgical groups: “Enucleation” (removal of the entire visible tumor) and “Complete resection” (removal of the tumor with an appropriate 5‐mm surgical margin).

Results

All 12 ICG‐containing tumors were clearly visible from the normal view but not from the flipped view. The tumor resection time was significantly longer in the “Complete resection” group than in the “Enucleation” group (p < .001). The ICG‐containing tumors showed a high tumor‐to background ratio from the normal (average = 45.8) and flipped (average = 19.2) views, indicating that the models including ICG‐containing tumors were useful for a surgical simulation in fluorescence‐guided surgery. The average mean fluorescence intensity of the wound bed was significantly higher in the “Enucleation” group than in the “Complete resection” group (p < .01). No decrease in fluorescence signal was found in the wound bed even at 2 days postresection.

Conclusion

Our surgical training model containing a fluorescent agent is safe, inexpensive, not harmful for humans, and easy to dispose after use. Our model would be beneficial for surgeons to learn NIR fluorescence imaging and to accelerate fluorescence‐guided cancer surgery into clinical application.

Near-Infrared Fluorescence Axillary Reverse Mapping (ARM) Procedure in Invasive Breast Cancer: Relationship between Fluorescence Signal in ARM Lymph Nodes and Clinical Outcomes

Simple Summary

Near-infrared fluorescence axillary reverse mapping (ARM) is a promising procedure for identification and preservation of arm lymphatic drainage during axillary lymph node dissection (ALND). We included 109 patients to analyze the indocyanine green fluorescence signal in ARM lymph nodes after resection. The fluorescence signal from ARM lymph nodes were compared with clinical findings to determine the importance of this criterion on the potential management of patients with ALND. ARM lymph nodes were identified in 94.5% of cases. The mean normalized fluorescence signal intensity value was 0.47 with no significant signal difference between metastatic and non-metastatic ARM lymph nodes. Only the preoperative diagnosis of metastasis in the axillary nodes of patients was significantly associated with a higher ARM node fluorescence signal intensity. Although preliminary results did not show that fluorescence signal intensity is a reliable diagnostic tool, the NIR fluorescence ARM procedure may be useful for ARM lymph node identification.

Abstract

The near-infrared (NIR) fluorescence axillary reverse mapping (ARM) procedure is a promising tool to identify and preserve arm lymphatic drainage during axillary lymph node dissection (ALND). The ARMONIC clinical trial was conducted to validate the technique on a large cohort of patients and to analyze the predictive clinical factors for ARM lymph node metastasis. For the first time, the fluorescence signal intensity from the ARM lymph nodes was measured and correlated with clinical findings. A total of 109 patients with invasive breast cancer and indications of mastectomy and ALND underwent the NIR fluorescence ARM procedure. Indocyanine green was administered by intradermal injection followed by intraoperative identification and resection of the ARM lymph nodes with NIR fluorescence camera guidance. The fluorescence signal intensity and signal distribution were then measured ex vivo and compared with clinical outcomes. ARM lymph nodes were successfully identified by fluorescence in 94.5% of cases. The mean normalized fluorescence signal intensity value was 0.47 with no significant signal difference between metastatic and non-metastatic ARM lymph nodes (p = 0.3728). At the microscopic level, the fluorescence signal distribution was focally intense in lymphoid tissue areas. Only the preoperative diagnosis of metastasis in the axillary nodes of patients was significantly associated with a higher ARM node fluorescence signal intensity (p = 0.0253), though it was not significantly associated with the pathological nodal (pN) status (p = 0.8081). Based on an optimal cut-off fluorescence value, the final sensitivity and specificity of the NIR fluorescence ARM procedure for ARM lymph node metastatic involvement were 64.7% and 47.3%, respectively. Although our preliminary results did not show that fluorescence signal intensity is a reliable diagnostic tool, the NIR fluorescence ARM procedure may be useful for ARM lymph node identification. Clinical trial registration: NCT02994225.

Consensus Conference Statement on the General Use of Near-infrared Fluorescence Imaging and Indocyanine Green Guided Surgery: Results of a Modified Delphi Study

BACKGROUND

In recent decades, the use of near-infrared light and fluorescence-guidance during open and laparoscopic surgery has exponentially expanded across various clinical settings. However, tremendous variability exists in how it is performed.

OBJECTIVE

In this first published survey of international experts on fluorescence-guided surgery, we sought to identify areas of consensus and nonconsensus across 4 areas of practice: fundamentals; patient selection/preparation; technical aspects; and effectiveness and safety.

METHODS

A Delphi survey was conducted among 19 international experts in fluorescence-guided surgery attending a 1-day consensus meeting in Frankfurt, Germany on September 8th, 2019. Using mobile phones, experts were asked to anonymously vote over 2 rounds of voting, with 70% and 80% set as a priori thresholds for consensus and vote robustness, respectively.

RESULTS

Experts from 5 continents reached consensus on 41 of 44 statements, including strong consensus that near-infrared fluorescence-guided surgery is both effective and safe across a broad variety of clinical settings, including the localization of critical anatomical structures like vessels, detection of tumors and sentinel nodes, assessment of tissue perfusion and anastomotic leaks, delineation of segmented organs, and localization of parathyroid glands. Although the minimum and maximum safe effective dose of ICG were felt to be 1 to 2 mg and >10 mg, respectively, there was strong consensus that determining the optimum dose, concentration, route and timing of ICG administration should be an ongoing research focus.

CONCLUSIONS

Although fluorescence imaging was almost unanimously perceived to be both effective and safe across a broad range of clinical settings, considerable further research remains necessary to optimize its use.

Safety and Efficacy of Cone-Beam Computed Tomography-Guided Lung Tumor Localization with a Near-Infrared Marker: A Retrospective Study of 175 Patients

Preoperative localization holds promise for overcoming the limitations of video-assisted thoracoscopic surgery (VATS) in the treatment of impalpable lung nodules. The purpose of this study was to assess the safety and efficacy of cone-beam computed tomography (CBCT)-guided localization using near-infrared (NIR) marking. Between 2017 and 2021, patients presenting with a solitary pulmonary nodule (SPN) who had undergone CBCT-guided lesion localization with indocyanine green (ICG) in a hybrid operating room were included. The primary outcomes were the efficacy of localization and the occurrence of complications. The study cohort consisted of 175 patients with the mean age of 58.76 years. The mean size and depth of the 175 SPNs were 8.34 mm and 5.3 mm, respectively. The mean time required for lesion marking was 14.71 min. Upon thoracoscopic inspection, the NIR tattoo was detected in the vast majority of the study participants (98.3%). An utility thoracotomy to allow digital palpation was required in two of the three patients in whom the tattoo was not identifiable. The perioperative survival rate was 100%, and the mean length of hospital stay was 3.09 days. We conclude that needle localization with ICG injection is a safe and feasible technique to localize SPNs prior to resection.

Successful laparoscopic resection of gastric lymphangioma under the intraoperative guidance of indocyanine green fluorescence imaging: A case report

Gastric lymphangioma (GLA) is an extremely rare tumor without an established therapeutic strategy. Surgical resection is considered the mainstay of treatment, although there is a high risk of local recurrence if negative margins are not achieved. A 51-year-old man underwent routine abdominal ultrasonography, which incidentally detected a 20-mm tumor adjacent to the lesser curvature of the stomach. GLA was suspected based on its polycystic appearance. After a 16-month monitoring period, laparoscopic resection was performed because of tumor growth and involvement of the left gastric artery. Intraoperative indocyanine green (ICG) navigation system revealed lymphatic drainage from the tumor, which we used to help determine the optimal excision line and minimize the loss of gastric volume. Pathological examination confirmed complete resection with negative margins and supported a diagnosis of lymphangioma. We performed laparoscopic radical resection of GLA under guidance from intraoperative ICG fluorescence imaging, which allowed us to maximize residual gastric volume.

The utility of ICG fluorescence for sentinel lymph node identification in head and neck melanoma

PURPOSE

Perform an evidence-based review to determine the utility of indocyanine green fluorescence (ICG) to detect sentinel lymph nodes (SLN) in patients with head and neck melanoma compared to blue dye or radiocolloid injection (RI).

MATERIALS AND METHODS

A systematic review of the literature was performed to identify patients with head and neck melanoma managed with ICG fluorescence. PubMed, Embase, and Cochrane Library databases were searched. Included studies were assessed for level of evidence. Patient demographics and data on SLN identification were determined.

RESULTS

Twenty-two studies encompassing 399 patients (75% male, 25% female, average age 57.1 years) met inclusion criteria. Publications comprised of two case reports, four retrospective case series, twelve cohort studies, and four clinical trials. Most common site of melanoma was scalp/temple/forehead (35%), cheek/midface (22%), and ear (17%) with an average Breslow thickness of 3.32 mm. SLN was identified in 80.7% (n = 201/249) of patients using ICG-RI, 85.2% (n = 75/88) using RI alone, and 63.4% (n = 52/82) using blue dye-RI.

CONCLUSIONS

ICG-^99mTc-nanocolloid hybrid tracer may be a superior alternative to blue dye + adiocolloid and has theoretical advantages compared to RI alone. Additional prospective randomized controlled trials are needed to further compare these methods and obtain data on false negative rates, operating room time, and cost effectiveness to fully elucidate the utility of ICG-^99mTc-nanocolloid over current methods used for SLN identification in this patient population.

3D printing fluorescent material with tunable optical properties

The 3D printing of fluorescent materials could help develop, validate, and translate imaging technologies, including systems for fluorescence-guided surgery. Despite advances in 3D printing techniques for optical targets, no comprehensive method has been demonstrated for the simultaneous incorporation of fluorophores and fine-tuning of absorption and scattering properties. Here, we introduce a photopolymer-based 3D printing method for manufacturing fluorescent material with tunable optical properties. The results demonstrate the ability to 3D print various individual fluorophores at reasonably high fluorescence yields, including IR-125, quantum dots, methylene blue, and rhodamine 590. Furthermore, tuning of the absorption and reduced scattering coefficients is demonstrated within the relevant mamalian soft tissue coefficient ranges of 0.005-0.05 mm-1 and 0.2-1.5 mm-1, respectively. Fabrication of fluorophore-doped biomimicking and complex geometric structures validated the ability to print feature sizes less than 200 μm. The presented methods and optical characterization techniques provide the foundation for the manufacturing of solid 3D printed fluorescent structures, with direct relevance to biomedical optics and the broad adoption of fast manufacturing methods in fluorescence imaging.

Effectiveness of antimicrobial photodynamic therapy with indocyanine green against the standard and fluconazole-resistant Candida albicans

Antimicrobial photodynamic therapy (aPDT) is an alternative approach. The current study aimed to investigate the efficacy of aPDT with indocyanine green (ICG) against two Candida albicans (C. albicans) strains. In this in vitro study, the inoculum of standard ATCC 10,231 (S) and fluconazole-resistant (FR) strains were adjusted to the turbidity of a 0.5 McFarland standard. Each strain was allocated into 4 groups: S1 and FR1) control groups, S2 and FR2) ICG-treated groups (1 µg/mL), S3 and FR3) laser-irradiated groups (wavelength: 810 nm; mode: continuous-wave; output power: 300 mW; spot size: 4.5 mm; exposure time: 120 s; radiation dose: 228 J/cm²), S4 and FR4) ICG-mediated-aPDT groups. After treatments, the number of colony-forming units per milliliter (CFU/mL) was calculated. Using the XTT reduction assay, the effects of each treatment on Candida biofilm formation were evaluated. Data were analyzed using SPSS software version 22. In both strains, the maximum number of CFUs was observed in the control group, followed by ICG-treated, laser-irradiated, and ICG-mediated-aPDT groups. In ATCC 10,231 strain, the XTT assay exhibited significant difference between ICG-mediated-aPDT and control groups (p < 0.0001). However, the ICG, laser, and ICG-mediated-aPDT groups in fluconazole-resistant strain showed significant differences when compared with the control (p < 0.05). The mean Candida CFUs and the XTT assay did not show any significant difference between the ATCC 10,231 and fluconazole-resistant strains with respect to each treatment. Data suggest ICG-mediated-aPDT could diminish Candida CFUs in laboratory; however, further studies are warranted to confirm its efficacy and safety to be applied in clinics.

Indocyanine Green Fluorescence Imaging with Lymphoscintigraphy Improves the Accuracy of Sentinel Lymph Node Biopsy in Melanoma

BACKGROUND

Despite advances in melanoma management, there remains room for improvement in the accuracy of sentinel lymph node biopsy. The authors analyzed a prospective cohort of patients with primary cutaneous melanoma who underwent sentinel lymph node biopsy with lymphoscintigraphy and indocyanine green fluorescence to evaluate the quality and accuracy of this technique.

METHODS

Consecutive primary cutaneous melanoma patients who underwent sentinel lymph node biopsy with radioisotope lymphoscintigraphy and indocyanine green fluorescence from 2012 to 2018 were prospectively enrolled. Analysis was performed of melanoma characteristics, means of identifying sentinel lymph nodes, sentinel lymph node status, and recurrence.

RESULTS

Five hundred ninety-four melanomas and 1827 nodes were analyzed; 1556 nodes (85.2 percent) were identified by radioactivity/fluorescence, 255 (14 percent) by radioactivity only, and 16 (0.9 percent) with indocyanine green only. There were 163 positive sentinel nodes. One hundred forty-seven (90.2 percent) were identified by radioactivity/fluorescence, 13 (8 percent) by radioactivity only, and three (0.6 percent) with fluorescence only. Of the 128 patients with a positive biopsy, eight patients' (6.3 percent) nodes were identified by radioactivity only and four (3.4 percent) with fluorescence only. There were 128 patients with a positive biopsy, 454 with a negative biopsy, and 12 patients who had a negative biopsy with subsequent nodal recurrence. Mean follow-up was 2.8 years.

CONCLUSIONS

In the study of the largest cohort of patients with primary cutaneous melanoma who underwent a sentinel lymph node biopsy with radioisotope lymphoscintigraphy and indocyanine green-based technology, the quality and accuracy of this technique are demonstrated. This has important implications for melanoma patients, as the adoption of this approach with subsequent accurate staging, adjuvant workup, and treatment may improve survival outcomes. .

CLINICAL QUESTION/LEVEL OF EVIDENCE

Diagnostic, II.

Recent Developments of ICG-Guided Sentinel Lymph Node Mapping in Oral Cancer

Sentinel lymph node (SLN) biopsy has gained attention as a method of minimizing the extent of neck dissection with a similar survival rate as elective neck dissection in oral cancer. Indocyanine green (ICG) imaging is widely used in the field of surgical oncology. Real-time ICG-guided SLN imaging has been widely used in minimally invasive surgeries for various types of cancers. Here, we provide an overview of conventional SLN biopsy and ICG-guided SLN mapping techniques for oral cancer. Although ICG has many strengths, it still has limitations regarding its potential use as an ideal compound for SLN mapping. The development of novel fluorophores and imaging technology is needed for accurate identification of SLNs, which will allow precision surgery that would reduce morbidities and increase patient survival.

Update on Osteosarcoma

PURPOSE OF REVIEW

Osteosarcoma (OSA) is the most common primary tumor of bone, mainly affecting children and adolescents. Here we discuss recent advances in surgical and systemic therapies, and highlight potentially new modalities in preclinical evaluation and prognostication.

RECENT FINDINGS

The advent of neoadjuvant and adjuvant chemotherapy has markedly improved the disease-free recurrence and overall survival of OSA. However, treatment efficacy has been stagnant since the 1980s. This plateau has prompted preclinical and clinical research into in precision surgery, inhaled chemotherapy to increase pulmonary drug concentration without systemic side effects, and novel immunomodulators intended to block molecular pathways associated with OSA proliferation and metastasis. With the advent of novel surgical techniques and new forms and vectors for chemotherapy, it is hoped that OSA treatment outcomes will exceed their currently sustained plateau in the near future.

The effect of indocyanine green-mediated photodynamic therapy in healing of experimentally induced oral mucosal traumatic ulcer in rat

Photodynamic therapy (PDT) is a promising approach for the healing of ulcerative lesions. This study aimed to investigate the effect of PDT using indocyanine green (ICG) in the healing of the experimentally induced oral mucosal traumatic ulcer in rat. Sixty adult male Sprague-Dawley rats were recruited in this experimental study. The ulceration was surgically made in the left cheek mucosa, and the rats were randomly assigned into four equal groups (n = 15). Oral ulcers in groups 1 and 2 were treated with the sterile saline solution (0.9%) and ICG (1 mg/ml). In group 3, laser irradiation was applied using the 810 nm diode laser in the continuous-wave mode for 30 s (light dose: 55 J/cm2, power: 300 mW, spot size: 4.5 mm). Following the topical application of ICG (1 mg/ml) in group 4, laser irradiation was performed in the same way as the previous group. After 24 h, treatments were repeated once more in all groups. The healing process was histopathologically assessed at the 3rd, 7th, and 14th days after ulceration. Wound healing was significantly accelerated in the ICG-mediated PDT group in comparison to the control group at all sampling time points (p < 0.005). However, the other groups displayed a similar healing rate (p > 0.05). Data suggest that ICG-mediated PDT has the potential to accelerate wound healing and prevent clinical infection in oral mucosal traumatic ulcers. However, further studies are required to confirm whether our results can be generalized to other wounds.

Indocyanine green fluorescence imaging for laparoscopic complex upper urinary tract reconstructions: a comparative study

Background

To describe our technique for using an intraureteral injection of indocyanine green (ICG) and visualization under near-infrared fluorescence (NIRF) to facilitate challenging upper urinary tract reconstructions (UUTRs) and to present the comparative outcomes.

Methods

We collected 36 patients who underwent laparoscopic UUTRs between April 2019 and March 2020, and we divided the patients into two groups based on the use of ICG (ICG group and non-ICG group). Demographic characteristics, perioperative outcomes, and functional outcomes were compared between the two groups.

Results

There were 18 cases in the ICG group and 18 cases in the non-ICG group, respectively. There were no differences in the baseline characteristics between the two groups. The intraoperative time to identification of the ureter (TIU; 20.9±11.7 vs. 30.0±14.6 min, P=0.03) and length of postoperative hospital stay (LPHS; 11.1±3.0 vs. 16.6±10.0 days, P=0.03) were significantly shorter in the ICG group. There was also a trend for lesser time for locating the stricture (43.0±27.9 vs. 55.4±18.6 min, P=0.14) and lower estimated blood loss (EBL) in the ICG group patients (88.3±75.4 vs. 91.7±46.2 mL, P=0.22). During the mean 3.8-month follow-up for the ICG group and the 6.2-month for the non-ICG group, there was a trend for more severe complications in the non-ICG group.

Conclusions

Visualizing intraureteral ICG under NIRF is useful in challenging UUTRs, allows for rapid ureteral identification and accurate real-time delineation of the ureteral stricture margins, and provides encouraging follow-up outcomes compared with those in the non-ICG group.

A Novel Parameter Identified Using Indocyanine Green Fluorescence Angiography may Contribute to Predicting Anastomotic Leakage in Gastric Cancer Surgery

BACKGROUND

Anastomotic leak is one of the most serious postoperative complications, and intraoperative adequate perfusion plays a key role in preventing its development in gastric cancer surgery. This study aimed to investigate the relationships between anastomotic leak and the parameters defined by an assessment of intraoperative anastomotic perfusion using a near-infrared indocyanine green (ICG) fluorescence system and to evaluate the usefulness of this ICG fluorescence assessment in gastric cancer surgery.

METHODS

We retrospectively reviewed data of 100 patients who underwent gastric cancer surgery. In a visual assessment based on fluorescence intensity, we classified ICG fluorescence image patterns as homogeneous, heterogeneous, or faint. In a chronological assessment, the first or second time point of ICG fluorescence appearance on one or the other side of the anastomosis was defined as FT or ST, respectively. The time difference in ICG fluorescence appearance between FT and ST was defined as TD. The relationships between anastomotic leak and the evaluated clinical factors, including the parameters identified by the ICG fluorescence assessment, were evaluated using univariate or multivariate analysis.

RESULTS

Although no signs of leak were found by surgeons' subjective judgments, four patients developed postoperative anastomotic leak of Clavien-Dindo grade III or IV. Multivariate analysis revealed that TD was an independent predictor of anastomotic leak (odds ratio 35.361, 95% confidence interval 1.489-839.923, p = 0.027).

CONCLUSIONS

A novel parameter identified using near-infrared ICG fluorescence assessment may be useful to predict anastomotic leak in gastric cancer surgery.

TRIAL REGISTRATION

UMIN Clinical Trials Registry: #UMIN000030747 ( https://www.umin.ac.jp/ctr/index.htm ).

Bimodal Imaging of Mouse Peripheral Nerves with Chlorin Tracers

Almost 17 million Americans have a history of cancer, a number expected to reach over 22 million by 2030. Cancer patients often undergo chemotherapy in the form of antineoplastic agents such as cis-platin and paclitaxel. Though effective, these agents can induce debilitating side effects; the most common neurotoxic effect, chemotherapy-induced peripheral neuropathy (CIPN), can endure long after treatment ends. Despite the widespread and chronic nature of the dysfunction, no tools exist to quantitatively measure chemotherapy-induced peripheral neuropathy. Such a tool would not only benefit patients but their stratification could also save significant financial and social costs associated with neuropathic pain. In our first step toward addressing this unmet clinical need, we explored a novel dual approach to localize peripheral nerves: Cerenkov luminescence imaging (CLI) and fluorescence imaging (FI). Our approach revolves around the targeting and imaging of voltage-gated sodium channel subtype Na_V1.7, highly expressed in peripheral nerves from both harvested human and mouse tissues. For the first time, we show that Hsp1a, a radiolabeled Na_V1.7-selective peptide isolated from Homoeomma spec. Peru, can serve as a targeted vector for delivering a radioactive sensor to the peripheral nervous system. In situ, we observe high signal-to-noise ratios in the sciatic nerves of animals injected with fluorescently labeled Hsp1a and radiolabeled Hsp1a. Moreover, confocal microscopy on fresh nerve tissue shows the same high ratios of fluorescence, corroborating our in vivo results. This study indicates that fluorescently labeled and radiolabeled Hsp1a tracers could be used to identify and demarcate nerves in a clinical setting.

Surgical Treatment of Intramedullary Hemangioblastomas: Current State of Problem (Review)

Intramedullary hemangioblastomas (HAB) refer to very rare highly vascularized vascular spinal cord tumors associated with various neurological disorders. Effective HAB therapy to a greater extent depends on diagnostic accuracy and the absence of intra- and postoperative complications.

The present study is a review of publications concerned with modern diagnostic and therapeutic techniques to control spinal HAB. The authors showed that perfusion computed tomography, computed tomographic angiography, and magnetic resonance angiography can be reasonably used for diagnosis and differentiation in a number of HAB due to their high vascularization. Preoperative embolization significantly reducing intraoperative bleeding risks is highly efficient. Some authors recommend this procedure in case of large lesions and high risks of intraoperative bleeding. The review also considered intraoperative imaging of a tumor and its feeding vessels using indocyanine green providing inspectability over the total tumor resection and clear imaging of tumor vascular architecture. The advantages and restrictions of the mentioned procedures were described.

pHLIP ICG for delineation of tumors and blood flow during fluorescence-guided surgery

Fluorescence imaging has seen enduring use in blood flow visualization and is now finding a new range of applications in image-guided surgery. In this paper, we report a translational study of a new fluorescent agent for use in surgery, pHLIP ICG, where ICG (indocyanine green) is a surgical fluorescent dye used widely for imaging blood flow. We studied pHLIP ICG interaction with the cell membrane lipid bilayer, the pharmacology and toxicology in vitro and in vivo (mice and dogs), and the biodistribution and clearance of pHLIP ICG in mice. The pHLIP ICG tumor targeting and imaging efficacy studies were carried out in several murine and human mouse tumor models. Blood vessels were imaged in mice and pigs. Clinical Stryker imaging instruments for endoscopy and open surgery were used in the study. Intravenously administered pHLIP ICG exhibits a multi-hour circulation half-life, offering protracted delineation of vasculature. As it clears from the blood, pHLIP ICG targets tumors and tumor stroma, marking them for surgical removal. pHLIP ICG is non-toxic, marks blood flow for hours after injection, and effectively delineates tumors for improved resection on the day after administration.

Photodynamic antimicrobial chemotherapy using indocyanine green in experimentally induced intraoral ulcers in rats

BACKGROUND

Photodynamic antimicrobial chemotherapy (PACT) is a promising modality for eradication of microorganisms from the wound. This study aimed to investigate the effectiveness of PACT using indocyanine green (ICG) for reduction of bacterial load of oral ulcers in rats and its impact on the healing process.

METHODS

In this experimental study, 50 adult male Sprague Dawley rats were recruited. Oral ulcers were surgically made on the left cheek mucosa, and animals were randomly assigned into five groups (n = 10). Wound site in groups 1, 2, and 3 was irrigated with the sterile saline (0.9%), chlorhexidine (CHX; 0.2%), and ICG solutions (1 mg/mL), respectively. Group 4 was exposed to laser irradiation using 810 nm diode laser on continuous-wave mode for 30 seconds (fluence: 55 J/cm² , power: 300 mW, spot size: 4.5 mm). In group 5, PACT was performed using topical application of ICG followed by laser irradiation in the same way as the previous group. Bacterial load of oral ulcers was assessed before and after each treatment modality. Besides, rats were sacrificed on the 5th day post ulceration and histological features of healing were evaluated.

RESULTS

Bacterial load was significantly reduced merely in the PACT-ICG-treated group by one log (P < .0001). Animals in the PACT-ICG-treated group also showed an accelerated healing in comparison with others on the 5th day of an experiment.

CONCLUSION

Photodynamic antimicrobial chemotherapy using topical application of ICG has a potential to reduce the bacterial load of oral ulcers and accelerate wound repair. Therefore, it can be considered as an alternative to currently available modalities for wound management.

Indocyanine green matching phantom for fluorescence-guided surgery imaging system characterization and performance assessment

SIGNIFICANCE

Expanded use of fluorescence-guided surgery with devices approved for use with indocyanine green (ICG) has led to a range of commercial systems available. There is a compelling need to be able to independently characterize system performance and allow for cross-system comparisons.

AIM

The goal of this work is to expand on previous proposed fluorescence imaging standard designs to develop a long-term stable phantom that spectrally matches ICG characteristics and utilizes 3D printing technology for incorporating tissue-equivalent materials.

APPROACH

A batch of test targets was created to assess ICG concentration sensitivity in the 0.3- to 1000-nM range, tissue-equivalent depth sensitivity down to 6 mm, and spatial resolution with a USAF test chart. Comparisons were completed with a range of systems that have significantly different imaging capabilities and applications, including the Li-Cor® Odyssey, Li-Cor® Pearl, PerkinElmer® Solaris, and Stryker® Spy Elite.

RESULTS

Imaging of the ICG-matching phantoms with all four commercially available systems showed the ability to benchmark system performance and allow for cross-system comparisons. The fluorescence tests were able to assess differences in the detectable concentrations of ICG with sensitivity differences >10× for preclinical and clinical systems. Furthermore, the tests successfully assessed system differences in the depth-signal decay rate, as well as resolution performance and image artifacts. The manufacturing variations, photostability, and mechanical design of the tests showed promise in providing long-term stable standards for fluorescence imaging.

CONCLUSIONS

The presented ICG-matching phantom provides a major step toward standardizing performance characterization and cross-system comparisons for devices approved for use with ICG. The developed hybrid manufacturing platform can incorporate long-term stable fluorescing agents with 3D printed tissue-equivalent material. Further, long-term testing of the phantom and refinements to the manufacturing process are necessary for future implementation as a widely adopted fluorescence imaging standard.

Near-infrared imaging and optical coherence tomography for intraoperative visualization of tumors

Surgical excision is the foundation of treatment for early-stage solid tumors in man and companion animals. Complete excision with appropriate margins of surrounding tumor-free tissue is crucial to survival. Intraoperative imaging allows real-time visualization of tumors, assessment of surgical margins, and, potentially, lymph nodes and satellite metastatic lesions, allowing surgeons to perform complete tumor resections while sparing surrounding vital anatomic structures. This Review will focus on the use of near-infrared imaging and optical coherence tomography for intraoperative tumor visualization.

Indocyanine Green Fluorescence Imaging with Lymphoscintigraphy for Sentinel Node Biopsy in Melanoma: Increasing the Sentinel Lymph Node-Positive Rate

INTRODUCTION

The goal of this study was to analyze patients who underwent a sentinel lymph node biopsy (SLNB) in melanoma with the combination of radioisotope lymphoscintigraphy and indocyanine green (ICG) fluorescence imaging to compare our true positive (TP) rate, a means to perform immediate analysis of the SLNB, with that of the literature.

METHODS

Consecutive cutaneous melanoma patients who underwent SLNB with lymphoscintigraphy and ICG-based fluorescence imaging by the senior author (BG) from 2012 to 2018 were prospectively enrolled. The average expected SLN-positive rate per T stage was calculated based on three studies and compared with our SLN-positive rate.

RESULTS

Overall, 574 consecutive patients were analyzed. Average Breslow thickness was 1.9 mm. A total of 1754 sentinel nodes were sampled; 1497 were identified by gamma probe signaling and ICG, 241 were identified by gamma probe signaling only, and 16 were identified by ICG only. There were 123 (21.4%) patients with at least one positive SLN; 113 (91.9%) had at least one positive node identified with both gamma probe signaling and ICG, 8 (6.5%) had positive node(s) identified with gamma probe signaling only, and 2 (1.6%) had positive node(s) identified with ICG only. There was an overall 21.4% SLN-positive rate, with 8% T1, 18.5% T2, 41.1% T3, and 52.4% T4, which is higher than the predicted rates for each stage.

CONCLUSIONS

With the largest cohort of patients reported who underwent a melanoma SLNB with lymphoscintigraphy and ICG, we demonstrated that this technique results in higher SLN-positive rates than predicted. Patients are being followed but, given the TP data, knowledge of our results may foster the use of this modality to improve staging and treatment options.

NIR fluorescence-guided tumor surgery: new strategies for the use of indocyanine green

Surgery is the frontline treatment for a large number of cancers. The objective of these excisional surgeries is the complete removal of the primary tumor with sufficient safety margins. Removal of the entire tumor is essential to improve the chances of a full recovery. To help surgeons achieve this objective, near-infrared fluorescence-guided surgical techniques are of great interest. The concomitant use of fluorescence and indocyanine green (ICG) has proved effective in the identification and characterization of tumors. Moreover, ICG is authorized by the Food and Drug Administration and the European Medicines Agency and is therefore the subject of a large number of studies. ICG is one of the most commonly used fluorophores in near-infrared fluorescence-guided techniques. However, it also has some disadvantages, such as limited photostability, a moderate fluorescence quantum yield, a high plasma protein binding rate, and undesired aggregation in aqueous solution. In addition, ICG does not specifically target tumor cells. One way to exploit the capabilities of ICG while offsetting these drawbacks is to develop high-performance near-infrared nanocomplexes formulated with ICG (with high selectivity for tumors, high tumor-to-background ratios, and minimal toxicity). In this review article, we focus on recent developments in ICG complexation strategies to improve near-infrared fluorescence-guided tumor surgery. We describe targeted and nontargeted ICG nanoparticle models and ICG complexation with targeting agents.

Optical Principles of Fluorescence-Guided Brain Tumor Surgery: A Practical Primer for the Neurosurgeon

Fluorescence-guided surgery is a rapidly growing field that has produced some of the most important innovations in surgical oncology in the past decade. These intraoperative imaging technologies provide information distinguishing tumor tissue from normal tissue in real time as the surgery proceeds and without disruption of the workflow. Many of these fluorescent tracers target unique molecular or cellular features of tumors, which offers the opportunity for identifying pathology with high precision to help surgeons achieve their primary objective of a maximal safe resection. As novel fluorophores and fluorescent probes emerge from preclinical development, a practical understanding of the principles of fluorescence remains critical for evaluating the clinical utility of these agents and identifying opportunities for further innovation. In this review, we provide an "in-text glossary" of the fundamental principles of fluorescence with examples of direct applications to fluorescence-guided brain surgery. We offer a detailed discussion of the various advantages and limitations of the most commonly used intraoperative imaging agents, including 5-aminolevulinic acid, indocyanine green, and fluorescein, with a particular focus on the photophysical properties of these specific agents as they provide a framework through which to understand the new agents that are entering clinical trials. To this end, we conclude with a survey of the fluorescent properties of novel agents that are currently undergoing or will soon enter clinical trials for the intraoperative imaging of brain tumors.

Hyperspectral Multiplexed Biological Imaging of Nanoprobes Emitting in the Short-Wave Infrared Region

Optical bioimaging with exogenous luminophores emitting in short-wave infrared spectral region (SWIR, ~ 1000-1700 nm) is a rapidly developing field, and the development of multiple SWIR-photoluminescent nanoprobes has recently been reported. In this regard, hyperspectral imaging (HSI), combined with unmixing algorithms, is a promising tool that can allow for efficient multiplexing of the SWIR-emitting nanoagents by their photoluminescence (PL) spectral profiles. The SWIR HSI technique reported here is developed to multiplex two types of nanoprobes: polymeric nanoparticles doped with organic dye (PNPs) and rare-earth doped fluoride nanoparticles (RENPs). Both types of nanoprobes exhibit PL in the same spectral range (~ 900-1200 nm), which hinders spectral separation of PL with optical filters and limits possibilities for their multiplexed imaging in biological tissues. By applying SWIR HSI, we exploited differences in the PL spectral profiles and achieved the spectrally selective and sensitive imaging of the PL signal from every type of nanoparticles. Unmixing of acquired data allowed for multiplexing of the spectrally overlapping nanoprobes by their PL profile. Both quantitative and spatial distribution for every type of nanoparticles were obtained from their mixed suspensions. Finally, the SWIR HSI technique with unmixing protocol was applied to in vivo imaging of mice subcutaneously injected with PNPs and RENPs. The applicability of hyperspectral techniques to multiplex nanoprobes in the in vivo imaging was successfully demonstrated.

Comparison of the efficacy of indocyanine green-mediated photodynamic therapy and nystatin therapy in treatment of denture stomatitis

BACKGROUND

Candida species have an influence in the pathogenesis of denture stomatitis. The current study aimed to investigate the efficacy of indocyanine green (ICG)-mediated photodynamic therapy (PDT) in combination with nystatin mouthwash (PDT + nystatin) for the treatment of denture stomatitis in comparison with routine antifungal therapy with nystatin alone.

METHODS

In this double-blind randomized clinical trial, 66 patients were randomly assigned into PDT + nystatin (n = 33) and nystatin (n = 33) groups, both groups were treated 3-times a day (15 days) with nystatin mouthwash, and PDT was performed twice once a week for the PDT + nystatin group. Briefly, ICG was applied on the palatal lesion and laser irradiation was performed using a diode laser (810 nm, 56 J/cm²). Nystatin group was also treated with sham laser in order to eliminate the possible psychological effects. The clinical and mycological evaluations were carried out at the baseline, during treatment, and the end of follow-up. Patients who completed the treatment and follow-up were eligible for statistical analysis (each group 28 cases).

RESULTS

Patient treatment with nystatin or PDT + nystatin reduced the lesions extension. Candida species were isolated from all patients and the number of Candida CFU in both groups showed a significant reduction at each post-treatment visit; however, the mean reduction achieved in the PDT + nystatin group was significantly higher than nystatin alone.

CONCLUSIONS

ICG-mediated PDT in combination with nystatin mouthwash can improve the clinical feature of denture stomatitis with no adverse effects; therefore, it could be used as an alternative to the currently available antifungal therapy using nystatin alone.

Digital and intelligent liver surgery in the new era: Prospects and dilemmas

Despite tremendous advances in traditional imaging technology over the past few decades, the intraoperative identification of lesions is still based on naked eye observation or pre-operative image evaluation. However, these two-dimensional image data cannot objectively reflect the complex anatomical structure of the liver and the detailed morphological features of the lesion, which directly limits the clinical application value of these imaging data in surgery in that it cannot improve the curative efficacy of surgery and the prognosis of the patient. This traditional mode of diagnosis and treatment has been changed by digital medical imaging technology in the new era with its significant function of accurate and efficient diagnosis of diseases, selection of reasonable treatment schemes, improvement of radical resection rate and reduction of surgical risk. In this paper, we reviewed the latest application of digital intelligent diagnosis and treatment technology related to liver surgery in the hope that it may help to achieve accurate treatment of liver surgery diseases.

Malignant Melanoma: Diagnostic and Management Update

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Summarize the changes to the American Joint Committee on Cancer Eighth Edition Melanoma Staging System. 2. List advances in genetic, molecular, and histopathologic melanoma diagnosis and prognostication. 3. Recommend sentinel lymph node biopsy and appropriate surgical margins based on individualized patient needs. 4. Recognize the currently available treatments for in-transit metastasis and advanced melanoma. 5. Describe current and future therapies for melanoma with distant visceral or brain metastases.

SUMMARY

Strides in melanoma surveillance, detection, and treatment continue to be made. The American Joint Committee on Cancer Eighth Edition Cancer Staging System has improved risk stratification of patients, introduced new staging categories, and resulted in stage migration of patients with improved outcomes. This review summarizes melanoma advances of the recent years with an emphasis on the surgical advances, including techniques and utility of sentinel node biopsy, controversies in melanoma margin selection, and the survival impact of time-to-treatment metrics. Once a disease manageable only with surgery, a therapeutic paradigm shift has given a more promising outlook to melanoma patients at any stage. Indeed, a myriad of novel, survival-improving immunotherapies have been introduced for metastatic melanoma and more recently in the high-risk adjuvant setting.

Intraoperative ICG-based imaging of liver neoplasms: a simple yet powerful tool. Preliminary results

BACKGROUND

Detecting small nodules that are grossly unidentifiable remains a major challenge in liver resection for cancer. Novel developments in navigation surgery, especially indocyanine green (ICG)-based fluorescence imaging, are making a clear breakthrough in addressing this issue. ICG is almost routinely administered during the preoperative stage in hepatobiliary surgery. However, its full potential has yet to be realized, partly because there are no precise guidelines regarding the optimal dose or timing of ICG injections before liver surgery. The main goal of this study was to design an algorithm for the management of ICG injections to achieve optimal liver staining results.

METHODS

Twenty-seven consecutive, unselected patients undergoing liver resection for cancer were enrolled and underwent preoperative liver function assessment by the LiMON test. Extra ICG i.v. injections at different doses and timings were performed. In vivo intraoperative analysis of the stain detected by near-infrared fluorescence imaging of the liver and ex vivo analysis of each resected nodule was performed and compared to the pathological analysis.

RESULTS

(i) The success rate of ICG injections in terms of liver staining was 92.6%; (ii) in the absence of or with 7 or more days from a previous ICG injection, the best dose to inject before the operation was 0.2 mg/kg, and the best timing was between 24 and 48 h before the scheduled surgery; and (iii) the ICG fluorescence patterns observed in the tumors were total fluorescence staining (41% of the cases), partial fluorescence staining (15%), rim fluorescence staining surrounding the tumor (30%), and no staining (15%).

CONCLUSIONS

This study is a building block for the characterization of liver nodules and the search for additional surface lesions undetected by preoperative radiological work-up-a crucial task for the successful treatment of liver cancer at an early stage using a safe, minimally invasive, and inexpensive technique.

Hybrid operating room for the intraoperative CT-guided localization of pulmonary nodules

Video-assisted thoracic surgery (VATS) requires preoperative computed tomography (CT)-guided localization of small pulmonary nodules or ground glass opacities (GGOs). However, this traditional two-stage approach is not devoid of potential complications, including wire dislodgement, pneumothorax, and/or hemothorax. With the advent of hybrid operating rooms (HORs), simultaneous single-stage localization and removal of such lesions has become possible. Here, we review the technical developments and the state-of-the-art in the field of intraoperative CT-guided localization and resection of small pulmonary nodules performed within a HOR.

A Novel Near-Infrared Fluorescent Probe TMTP1-PEG4-ICG for in Vivo Tumor Imaging

Molecular imaging agents are considered to be promising tracers for tumor imaging and guided therapy. TMTP1 was screened through the FliTrx bacterial peptide display system in our laboratory previously and shown to specifically target to primary tumors and metastatic foci. In this study, small peptide TMTP1 was designed to conjugate to a near-infrared fluorescent agent ICG derivative ICG-OSu through PEG4, forming the novel probe TMTP1-PEG4-ICG. It was successfully synthesized and certified. CCK-8 assay showed that it was nontoxic to normal cells and cancerous cells. Dynamics study indicated that the probe was cleared through the liver-intestine and kidney-bladder pathway. Tumor targeting capability of this probe in vitro was evaluated on 4T1, SiHa, HeLa, S12, and HaCaT cells by flow cytometry. In vivo imaging of 4T1 and HeLa tumor-bearing mice further identified the tumor homing ability. As we had expected, the probe showed excellent affinity to cancer cells not only in vitro but also in vivo, whether in murine tumor or humanized tumor. In conclusion, TMTP1-PEG4-ICG demonstrated ideal imaging effects on tumor-bearing mice model, providing new opportunities for tumor diagnostic or guiding resection.

Contrast-Enhanced Near-Infrared Optical Imaging Detects Exacerbation and Amelioration of Murine Muscular Dystrophy

Assessment of muscle pathology is a key outcome measure to measure the success of clinical trials studying muscular dystrophies; however, few robust minimally invasive measures exist. Indocyanine green (ICG)-enhanced near-infrared (NIR) optical imaging offers an objective, minimally invasive, and longitudinal modality that can quantify pathology within muscle by imaging uptake of ICG into the damaged muscles. Dystrophic mice lacking dystrophin (mdx) or gamma-sarcoglycan (Sgcg^−/−) were compared to control mice by NIR optical imaging and magnetic resonance imaging (MRI). We determined that optical imaging could be used to differentiate control and dystrophic mice, visualize eccentric muscle induced by downhill treadmill running, and restore the membrane integrity in Sgcg^−/− mice following adeno-associated virus (AAV) delivery of recombinant human SGCG (desAAV8hSGCG). We conclude that NIR optical imaging is comparable to MRI and can be used to detect muscle damage in dystrophic muscle as compared to unaffected controls, monitor worsening of muscle pathology in muscular dystrophy, and assess regression of pathology following therapeutic intervention in muscular dystrophies.