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

Perfusion Visualization during Ileal J-Pouch Formation—A Proposal for the Standardization of Intraoperative Imaging with Indocyanine Green Near-Infrared Fluorescence and a Postoperative Follow-Up in IBD Surgery

Background: An anastomotic leak (AL) after a restorative proctocolectomy and an ileal J-pouch increases morbidity and the risk of pouch failure. Thus, a perfusion assessment during J-pouch formation is crucial. While indocyanine green near-infrared fluorescence (ICG-NIRF) has shown potential to reduce ALs, its suitability in a restorative proctocolectomy remains unclear. We aimed to develop a standardized approach for investigating ICG-NIRF and ALs in pouch surgery. Methods: Patients undergoing a restorative proctocolectomy with an ileal J-pouch for ulcerative colitis at an IBD-referral-center were included in a prospective study in which an AL within 30 postoperative days was the primary outcome. Intraoperatively, standardized perfusion visualization with ICG-NIRF was performed and video recorded for postoperative analysis at three time points. Quantitative clinical and technical variables (secondary outcome) were correlated with the primary outcome by descriptive analysis and logistic regression. A novel definition and grading of AL of the J-pouch was applied. A postoperative pouchoscopy was routinely performed to screen for AL. Results: Intraoperative ICG-NIRF-visualization and its postoperative visual analysis in 25 patients did not indicate an AL. The anastomotic site after pouch formation appeared completely fluorescent with a strong fluorescence signal (category 2) in all cases of ALs (4 of 25). Anastomotic site was not changed. ICG-NIRF visualization was reproducible and standardized. Logistic regression identified a two-stage approach vs. a three-stage approach (Odds ratio (OR) = 20.00, 95% confidence interval [CI] = 1.37–580.18, p = 0.029) as a risk factor for ALs. Conclusion: We present a standardized, comparable approach of ICG-NIRF visualization in pouch surgery. Our data indicate that the visual interpretation of ICG-NIRF alone may not detect ALs of the pouch in all cases—quantifiable, objective methods of interpretation may be required in the future.

Cost-effectiveness of indocyanine green angiography in postmastectomy breast reconstruction

BACKGROUND

Mastectomy skin flap necrosis is a major complication of skin- or nipple-sparing mastectomy. Indocyanine green angiography (ICGA) is a novel technology that can identify flaps at risk of necrosis, but there is paucity of cost-effectiveness data particularly in the Australian context. We evaluated its cost-effectiveness in breast reconstruction surgery.

METHODS

Single-institution retrospective study of 295 implant-based breast reconstructions using ICGA compared with 228 reconstructions without ICGA from 2015 to 2020. Costs were calculated using Medicare item numbers and micro-costing analysis. Break-even point analysis determined the number needed to break-even. Cost-utility analysis compared probabilities of ischaemic complications and utility estimates derived from surveys of surgeons to fit into a decision model.

RESULTS

There were 295 breast reconstructions using ICGA with a total cost of AU$164,657. The average cost of treating an ischaemic complication was AU$21,375. Use of ICGA reduced the ischaemic complication rate from 14.9% to 8.8%. Ischaemic complications were prevented in 18 breasts resulting in gross cost savings of AU$384,745 and net savings of AU$220,088. Three hundred eighteen cases using ICGA are needed to break-even. The decision model demonstrated a baseline cost difference of AU$1,179, a quality-adjusted life-years (QALY) difference of 1.77, and an incremental cost-utility ratio (ICUR) of AU$656 per QALY favouring ICGA.

CONCLUSIONS

Routine use of ICGA during implant-based breast reconstruction is a cost-effective intervention for the reduction of ischaemic complications in the Australian setting. ICGA use was associated with a gain of 1.77 additional years of perfect health at a cost of AU$656 more per year.

Fluorescence Imaging in Colorectal Surgery: An Updated Review and Future Trends

Fluorescence imaging in colorectal surgery is considered a novel predominantly intraoperative method of ensuring a greater surgical success. The use of fluorescence is linked to advanced tumor visualization and projection of its lymphatics, both vessels and nodes, which results in a higher chance of achieving a total excision. Additionally, iatrogenic complications prove to be reduced using fluorescence during the surgical excision. The combination of fluorescence and artificial intelligence to better facilitate oncological surgery will soon become an established approach in operating rooms worldwide.

ICG-Guided Lymphadenectomy during Surgery for Colon and Rectal Cancer-Interim Analysis of the GREENLIGHT Trial

Lymphadenectomy is crucial for an optimal oncologic resection of colon and rectal cancers. However, without a direct visualization, an aberrant route of lymph node (LN) diffusion might remain unresected. Indocyanine-green (ICG) lymphatic mapping permits a real-time LNs visualization. We designed the GREENLIGHT trial to explore in 100 patients undergoing robotic colorectal resection the clinical significance of a D3 ICG-guided lymphadenectomy. The primary endpoint was the number of patients in whom ICG changed the extent of lymphadenectomy. We report herein the interim analysis on the first 70 patients. After endoscopic ICG injection 24 h (n = 49) or 72 h (n = 21) ahead, 19, 20, and 31 patients underwent right colectomy, left colectomy, and anterior rectal resection. The extent of lymphadenectomy changed in 35 (50%) patients, mostly (29 (41.4%)) for the identification of LNs (median two) outside the standard draining basin. Identification of such LNs was less frequent in rectal tumors that had undergone chemoradiotherapy (26.3%) (p > 0.05). A non-significant correlation between time-to-ICG injection and identification of aberrant LNs was observed (48.9% at 24 h vs. 23.8% at 72 h). The presence of LN metastases did not affect a proper fluorescent mapping. These data indicate that ICG lymphatic mapping provides relevant information in 50% of patients, thus increasing the accuracy of potentially curative resections.

Current and Potential Applications for Indocyanine Green in Liver Transplantation

Indocyanine green (ICG) is a fluorescent dye taken up and almost exclusively cleared by the liver. Measurement of its clearance and visualization of its fluorescence make it suitable for a number of potential applications in liver transplantation including assessment of liver function and real-time assessment of arterial, venous, and biliary structures. ICG clearance can be used to assess donor graft quality before procurement and graft metabolic function before transplant using normothermic ex vivo machine perfusion. ICG clearance in the post-liver transplantation period is able to predict recipient outcomes with correlations to early allograft dysfunction and postoperative complications. After absorbing light in the near-infrared spectrum, ICG also emits fluorescence at 835 nm. This allows the assessment of vascular patency after reconstruction and patterns of liver perfusion in real time. ICG perfusion patterns after revascularization are also associated with posttransplant graft function and survival. ICG fluorescence cholangiography is routine in a number of centers and acts as an aid to identifying the optimal point of bile duct division during living donor liver transplantation to optimize safety for both donor and recipient. In summary, ICG is a versatile tool and has a number of useful applications in the liver transplantation journey including assessment of liver function, perfusion assessment, and cholangiography. Further research and clinical trials are required to validate and standardize its routine use in liver transplantation.

Primary and metastatic peritoneal surface malignancies

Peritoneal surface malignancies comprise a heterogeneous group of primary tumours, including peritoneal mesothelioma, and peritoneal metastases of other tumours, including ovarian, gastric, colorectal, appendicular or pancreatic cancers. The pathophysiology of peritoneal malignancy is complex and not fully understood. The two main hypotheses are the transformation of mesothelial cells (peritoneal primary tumour) and shedding of cells from a primary tumour with implantation of cells in the peritoneal cavity (peritoneal metastasis). Diagnosis is challenging and often requires modern imaging and interventional techniques, including surgical exploration. In the past decade, new treatments and multimodal strategies helped to improve patient survival and quality of life and the premise that peritoneal malignancies are fatal diseases has been dismissed as management strategies, including complete cytoreductive surgery embedded in perioperative systemic chemotherapy, can provide cure in selected patients. Furthermore, intraperitoneal chemotherapy has become an important part of combination treatments. Improving locoregional treatment delivery to enhance penetration to tumour nodules and reduce systemic uptake is one of the most active research areas. The current main challenges involve not only offering the best treatment option and developing intraperitoneal therapies that are equivalent to current systemic therapies but also defining the optimal treatment sequence according to primary tumour, disease extent and patient preferences. New imaging modalities, less invasive surgery, nanomedicines and targeted therapies are the basis for a new era of intraperitoneal therapy and are beginning to show encouraging outcomes.

Assessing the development status of intraoperative fluorescence imaging for perfusion assessments, using the IDEAL framework

Objectives

Intraoperative fluorescence imaging is currently used in a variety of surgical fields for four main purposes: assessing tissue perfusion; identifying/localizing cancer; mapping lymphatic systems; and visualizing anatomy. To establish evidence-based guidance for research and practice, understanding the state of research on fluorescence imaging in different surgical fields is needed. We evaluated the evidence on fluorescence imaging for perfusion assessments using the Idea, Development, Exploration, Assessment, Long Term Study (IDEAL) framework, which was designed for describing the stages of innovation in surgery and other interventional procedures.

Design

Narrative literature review with analysis of IDEAL stage of each field of study.

Setting

All publications on intraoperative fluorescence imaging for perfusion assessments reported in PubMed through 2019 were identified for six surgical procedures: coronary artery bypass grafting (CABG), upper gastrointestinal (GI) surgery, colorectal surgery, solid organ transplantation, reconstructive surgery, and cerebral aneurysm surgery.

Main outcome measures

The IDEAL stage of research evidence was determined for each specialty field using a previously described approach.

Results

196 articles (15 003 cases) were selected for analysis. Current status of research evidence was determined to be IDEAL Stage 2a for upper GI and transplantation surgery, IDEAL 2b for CABG, colorectal and cerebral aneurysm surgery, and IDEAL Stage 3 for reconstructive surgery. Using the technique resulted in a high (up to 50%) rate of revisions among surgical procedures, but its efficacy improving postoperative outcomes has not yet been demonstrated by randomized controlled trials in any discipline. Only one possible adverse reaction to intravenous indocyanine green was reported.

Conclusions

Using fluorescence imaging intraoperatively to assess perfusion is feasible and appears useful for surgical decision making across a range of disciplines. Identifying the IDEAL stage of current research knowledge aids in planning further studies to establish the potential for patient benefit.

Fluorescent cholangiography: An up-to-date overview twelve years after the first clinical application

Laparoscopic cholecystectomy (LC) is one of the most frequently performed gastrointestinal surgeries worldwide. Bile duct injury (BDI) represents the most serious complication of LC, with an incidence of 0.3%-0.7%, resulting in significant perioperative morbidity and mortality, impaired quality of life, and high rates of subsequent medico-legal litigation. In most cases, the primary cause of BDI is the misinterpretation of biliary anatomy, leading to unexpected biliary lesions. Near-infrared fluorescent cholangiography is widely spreading in clinical practice to delineate biliary anatomy during LC in elective and emergency settings. The primary aim of this article was to perform an up-to-date overview of the evolution of this method 12 years after the first clinical application in 2009 and to highlight all advantages and current limitations according to the available scientific evidence.

Short-Wave Infrared Emitting Nanocomposites for Fluorescence-Guided Surgery

Fluorescence-guided surgery (FGS) is an emerging technique for tissue visualization during surgical procedures. Structures of interest are labeled with exogenous probes whose fluorescent emissions are acquired and viewed in real-time with optical imaging systems. This study investigated rare-earth-doped albumin-encapsulated nanocomposites (REANCs) as short-wave infrared emitting contrast agents for FGS. Experiments were conducted using an animal model of 4T1 breast cancer. The signal-to-background ratio (SBR) obtained with REANCs was compared to values obtained using indocyanine green (ICG), a near-infrared dye used in clinical practice. Prior to resection, the SBR for tumors following intratumoral administration of REANCs was significantly higher than for tumors injected with ICG. Following FGS, evaluation of fluorescence intensity levels in excised tumors and at the surgical bed demonstrated higher contrast between tissues at these sites with REANC contrast than ICG. REANCs also demonstrated excellent photostability over 2 hours of continuous illumination, as well as the ability to perform FGS under ambient lighting, establishing these nanocomposites as a promising contrast agent for FGS applications.

Receptor-Targeted Fluorescence-Guided Surgery With Low Molecular Weight Agents

Cancer surgery remains the primary treatment option for most solid tumors and can be curative if all malignant cells are removed. Surgeons have historically relied on visual and tactile cues to maximize tumor resection, but clinical data suggest that relapse occurs partially due to incomplete cancer removal. As a result, the introduction of technologies that enhance the ability to visualize tumors in the operating room represents a pressing need. Such technologies have the potential to revolutionize the surgical standard-of-care by enabling real-time detection of surgical margins, subclinical residual disease, lymph node metastases and synchronous/metachronous tumors. Fluorescence-guided surgery (FGS) in the near-infrared (NIRF) spectrum has shown tremendous promise as an intraoperative imaging modality. An increasing number of clinical studies have demonstrated that tumor-selective FGS agents can improve the predictive value of fluorescence over non-targeted dyes. Whereas NIRF-labeled macromolecules (i.e., antibodies) spearheaded the widespread clinical translation of tumor-selective FGS drugs, peptides and small-molecules are emerging as valuable alternatives. Here, we first review the state-of-the-art of promising low molecular weight agents that are in clinical development for FGS; we then discuss the significance, application and constraints of emerging tumor-selective FGS technologies.

Biophysics inspired artificial intelligence for colorectal cancer characterization

Over the last ten years artificial intelligence (AI) methods have begun to pervade even the most common everyday tasks such as email filtering and mobile banking. While the necessary quality and safety standards may have understandably slowed the introduction of AI to healthcare when compared with other industries, we are now beginning to see AI methods becoming more available to the clinician in select settings. In this paper we discuss current AI methods as they pertain to gastrointestinal procedures including both gastroenterology and gastrointestinal surgery. The current state of the art for polyp detection in gastroenterology is explored with a particular focus on deep leaning, its strengths, as well as some of the factors that may limit its application to the field of surgery. The use of biophysics (utilizing physics to study and explain biological phenomena) in combination with more traditional machine learning is also discussed and proposed as an alternative approach that may solve some of the challenges associated with deep learning. Past and present uses of biophysics inspired AI methods, such as the use of fluorescence guided surgery to aid in the characterization of colorectal lesions, are used to illustrate the role biophysics-inspired AI can play in the exciting future of the gastrointestinal proceduralist.

Fluorescence-based pancreas stump perfusion is associated with postoperative acute pancreatitis after pancreatoduodenectomy a prospective cohort study

BACKGROUND

Postoperative acute pancreatitis (POAP) emerges as a distinct pancreas-specific complication increasing both the risk and the burden of POPF after pancreatoduodenectomy. Among various risk factors, pancreas stump (PS) hypoperfusion might play a role in POAP occurrence but has never been investigated. The current study aimed at evaluating the feasibility of intraoperative fluorescence angiography (IOFA) of the PS using ICG and its association with POAP.

METHODS

Consecutive patients who underwent pancreatoduodenectomy for a periampullary tumor with pancreatojejunostomy and PS perfusion assessment using IOFA between January 2020 and November 2020 were prospectively included. Perioperative management and surgical strategy were standardized. IOFA of the pancreas stump was performed before fashioning pancreatojejunostomy. POAP was defined according to the Connor definition and was confirmed upon radiological blind review. Outcomes between patients with normally perfused and hypoperfused PS were compared. POAP was the primary endpoint.

RESULTS

Among 30 patients, nine patients (30%) developed POAP according to the Connor definition, and six patients (20%) had CT-confirmed POAP. Upon IOFA, six patients (20%) presented PS hypoperfusion; of which one patient underwent extended pancreatectomy further to the left. PS hypoperfusion was statistically associated with the occurrence of POAP (80% vs. 16%; p = 0.011) and CT-confirmed POAP (60% vs. 12%; p = 0.041). Clinically relevant POPF rate was 40% in case of PS hypoperfusion and 4% in case of normal PS perfusion (p = 0.064).

CONCLUSIONS

PS perfusion assessment using IOFA seems safe and reliable to anticipate POAP. PS IOFA could be considered as a potential tool for perioperative assessment of surgical risk after pancreatoduodenectomy.

Enhancing colorectal anastomotic safety with indocyanine green fluorescence angiography: An update

Reducing anastomotic leak (AL) continues to be a main focus in colorectal research. Several new technologies have been developed with an aim to reduce this from mechanical devices to advanced imaging techniques. Fluorescence angiography (FA) with indocyanine green (ICG) in colorectal surgery is now a well-established technique and may have a role in reducing AL. By using FA, we are able to have a visual representation of perfusion which aids intraoperative decision making. The main impact is change in the level of bowel transection at the proximal side of an anastomosis and provide a more objective and confident assessment of bowel perfusion. Previous studies have shown that routine FA use is safe and reproducible. Recent results from randomized control trials and meta-analyses show that FA use reduces the rate of anastomotic leak. The main limitation of FA is its lack of ability to quantify perfusion. Novel technologies are being developed that will quantify tissue perfusion and oxygenation. Overall, FA is a safe and feasible technique which may have a role in reducing AL.

Novel Multimodal, Multiscale Imaging System with Augmented Reality

A novel multimodal, multiscale imaging system with augmented reality capability were developed and characterized. The system offers 3D color reflectance imaging, 3D fluorescence imaging, and augmented reality in real time. Multiscale fluorescence imaging was enabled by developing and integrating an in vivo fiber-optic microscope. Real-time ultrasound-fluorescence multimodal imaging used optically tracked fiducial markers for registration. Tomographical data are also incorporated using optically tracked fiducial markers for registration. Furthermore, we characterized system performance and registration accuracy in a benchtop setting. The multiscale fluorescence imaging facilitated assessing the functional status of tissues, extending the minimal resolution of fluorescence imaging to ~17.5 µm. The system achieved a mean of Target Registration error of less than 2 mm for registering fluorescence images to ultrasound images and MRI-based 3D model, which is within clinically acceptable range. The low latency and high frame rate of the prototype system has shown the promise of applying the reported techniques in clinically relevant settings in the future.