IntAct: intra-operative fluorescence angiography to prevent anastomotic leak in rectal cancer surgery: a randomized controlled trial

ARIA II: a randomized controlled trial of near-infrared Angiography during RectosIgmoid resection and Anastomosis in women with ovarian cancer

BACKGROUND

Ovarian cancer with extensive metastatic disease involving pelvic structures often requires rectosigmoid resection for complete gross resection; however, it is associated with increased surgical morbidity. There are limited data, and none in ovarian cancer, on near-infrared assessment of perfusion in rectosigmoid resections with anastomosis.

PRIMARY OBJECTIVE

To compare the rate of pelvic complications (pelvic abscesses, anastomotic leaks, and infections) within 30 days of surgery with and without near-infrared assessment of perfusion at time of rectosigmoid resection and re-anastomosis in patients undergoing cytoreductive surgery for ovarian cancer.

STUDY HYPOTHESIS

We hypothesize the use of near-infrared technology (intravenous indocyanine green and endoscopic near-infrared fluorescence imaging), compared with standard intra-operative assessment, to evaluate anastomotic perfusion at time of rectosigmoid resection and re-anastomosis will result in lower rates of post-operative pelvic complications.

TRIAL DESIGN

This is a planned multicenter randomized controlled trial. Patients who undergo rectosigmoid resection as part of their ovarian cytoreductive surgery will be randomized 1:1 to standard assessment of anastomosis with the surgeon's usual technique (control arm) or assessment with near-infrared angiography using indocyanine green and endoscopic fluorescence imaging (experimental arm). Randomization will occur after rectosigmoid resection has been completed and the surgeon declares their plan to create a diverting ostomy. Randomization will be stratified by plan for diverting ostomy.

MAJOR INCLUSION/EXCLUSION CRITERIA

Main inclusion criteria include patients with primary or recurrent ovarian, fallopian tube, or primary peritoneal cancer who are scheduled for cytoreductive surgery with suspected need for low-anterior rectosigmoid resection.

PRIMARY ENDPOINT

Rate of 30-day post-operative pelvic complications.

SAMPLE SIZE

310 (155 per arm) ESTIMATED DATES FOR COMPLETING ACCRUAL AND PRESENTING RESULTS: Q2 2027 and Q4 2027, respectively.

TRIAL REGISTRATION

NCT04878094.

Intraoperative near infrared functional imaging of rectal cancer using artificial intelligence methods - now and near future state of the art

Colorectal cancer remains a major cause of cancer death and morbidity worldwide. Surgery is a major treatment modality for primary and, increasingly, secondary curative therapy. However, with more patients being diagnosed with early stage and premalignant disease manifesting as large polyps, greater accuracy in diagnostic and therapeutic precision is needed right from the time of first endoscopic encounter. Rapid advancements in the field of artificial intelligence (AI), coupled with widespread availability of near infrared imaging (currently based around indocyanine green (ICG)) can enable colonoscopic tissue classification and prognostic stratification for significant polyps, in a similar manner to contemporary dynamic radiological perfusion imaging but with the advantage of being able to do so directly within interventional procedural time frames. It can provide an explainable method for immediate digital biopsies that could guide or even replace traditional forceps biopsies and provide guidance re margins (both areas where current practice is only approximately 80% accurate prior to definitive excision). Here, we discuss the concept and practice of AI enhanced ICG perfusion analysis for rectal cancer surgery while highlighting recent and essential near-future advancements. These include breakthrough developments in computer vision and time series analysis that allow for real-time quantification and classification of fluorescent perfusion signals of rectal cancer tissue intraoperatively that accurately distinguish between normal, benign, and malignant tissues in situ endoscopically, which are now undergoing international prospective validation (the Horizon Europe CLASSICA study). Next stage advancements may include detailed digital characterisation of small rectal malignancy based on intraoperative assessment of specific intratumoral fluorescent signal pattern. This could include T staging and intratumoral molecular process profiling (e.g. regarding angiogenesis, differentiation, inflammatory component, and tumour to stroma ratio) with the potential to accurately predict the microscopic local response to nonsurgical treatment enabling personalised therapy via decision support tools. Such advancements are also applicable to the next generation fluorophores and imaging agents currently emerging from clinical trials. In addition, by providing an understandable, applicable method for detailed tissue characterisation visually, such technology paves the way for acceptance of other AI methodology during surgery including, potentially, deep learning methods based on whole screen/video detailing.

Clinical and computational development of a patient-calibrated ICGFA bowel transection recommender

INTRODUCTION

Intraoperative indocyanine green fluorescence angiography (ICGFA) aims to reduce colorectal anastomotic complications. However, signal interpretation is inconsistent and confounded by patient physiology and system behaviours. Here, we demonstrate a proof of concept of a novel clinical and computational method for patient calibrated quantitative ICGFA (QICGFA) bowel transection recommendation.

METHODS

Patients undergoing elective colorectal resection had colonic ICGFA both immediately after operative commencement prior to any dissection and again, as usual, just before anastomotic construction. Video recordings of both ICGFA acquisitions were blindly quantified post hoc across selected colonic regions of interest (ROIs) using tracking-quantification software and computationally compared with satisfactory perfusion assumed in second time-point ROIs, demonstrating 85% agreement with baseline ICGFA. ROI quantification outputs detailing projected perfusion sufficiency-insufficiency zones were compared to the actual surgeon-selected transection/anastomotic construction site for left/right-sided resections, respectively. Anastomotic outcomes were recorded, and tissue lactate was also measured in the devascularised colonic segment in a subgroup of patients. The novel perfusion zone projections were developed as full-screen recommendations via overlay heatmaps.

RESULTS

No patient suffered intra- or early postoperative anastomotic complications. Following computational development (n = 14) the software recommended zone (ROI) contained the expert surgical site of transection in almost all cases (Jaccard similarity index 0.91) of the nine patient validation series. Previously published ICGFA time-series milestone descriptors correlated moderately well, but lactate measurements did not. High resolution augmented reality heatmaps presenting recommendations from all pixels of the bowel ICGFA were generated for all cases.

CONCLUSIONS

By benchmarking to the patient's own baseline perfusion, this novel QICGFA method could allow the deployment of algorithmic personalised NIR bowel transection point recommendation in a way fitting existing clinical workflow.

Intraoperative left-sided colorectal anastomotic testing in clinical practice: a multi-treatment machine-learning analysis of the iCral3 prospective cohort

BACKGROUND

Current evidence about intraoperative anastomotic testing after left-sided colorectal resections is still controversial. The aim of this study was to analyze the impact of Indocyanine Green fluorescent angiography (ICG-FA) and air-leak test (ALT) over standard assessment on anastomotic leakage (AL) rates according to surgeon's perception of anastomosis perfusion and/or integrity in clinical practice.

METHODS

A database of 2061 patients who underwent left-sided colorectal resections was selected from patients enrolled in a prospective multicenter study. It was retrospectively analyzed through a multi-treatment machine-learning model considering standard visual assessment (NW; No. = 899; 43.6%) as the reference treatment arm, compared to ICG-FA alone (WP; No. = 409; 19.8%), ALT alone (WI; No. = 420; 20.4%) or both (WPI; No. = 333; 16.2%). Twenty-four covariates potentially affecting the outcomes were included and balanced into the model within the subgroups. The primary endpoint was AL, the secondary endpoints were overall morbidity (OM), major morbidity (MM), reoperation for AL, and mortality. All the results were reported as odds ratio (OR) with 95% confidence intervals (95%CI).

RESULTS

The WPI subgroup showed significantly higher AL risk (OR 1.91; 95% CI 1.02-3.59; p 0.043), MM risk (OR 2.35; 95% CI 1.39-3.97; p 0.001), and reoperation for AL risk (OR 2.44; 95% CI 1.12-5.31; p 0.025). No other significant differences were recorded.

CONCLUSIONS

This study showed that the surgeons' perception of both anastomotic perfusion and integrity (WPI subgroup) was associated to a significantly higher risk of AL and related morbidity, notwithstanding the extensive use of both ICG-FA and ALT testing.

Indocyanine green fluorescence angiography in colorectal surgery: A retrospective case-control analysis in Mexico

INTRODUCTION AND AIMS

An anastomotic leak is one of the most dreaded complications in colorectal surgery because it increases postoperative morbidity and mortality. The aim of the present study was to identify whether indocyanine green fluorescence angiography (ICGFA) reduced the anastomotic dehiscence rate in colorectal surgery.

MATERIAL AND METHODS

A retrospective study on patients that underwent colorectal surgery with colonic resection or low anterior resection and primary anastomosis, within the time frame of January 2019 and September 2021, was conducted. The patients were divided into the case group, in which ICGFA was performed for the intraoperative evaluation of blood perfusion at the anastomosis site, and the control group, in which ICGFA was not utilized.

RESULTS

A total of 168 medical records were reviewed, resulting in 83 cases and 85 controls. Inadequate perfusion that required changing the surgical site of the anastomosis was identified in 4.8% of the case group (n = 4). A trend toward reducing the leak rate with ICGFA was identified (6% [n = 5] in the cases vs 7.1% in the controls [n = 6] [p = 0.999]). The patients that underwent anastomosis site change due to inadequate perfusion had a 0% leak rate.

CONCLUSIONS

ICGFA as a method to evaluate intraoperative blood perfusion showed a trend toward reducing the incidence of anastomotic leak in colorectal surgery.

Indocyanine green fluorescence angiography could reduce the risk of anastomotic leakage in rectal cancer surgery: a systematic review and meta-analysis of randomized controlled trials

AIM

Several papers have shown that use of indocyanine green (ICG) decreases incidence of anastomotic leakage (AL) during colonic surgery, but no clear evidence has been found for rectal cancer surgery. Therefore, with this systematic review and meta-analysis of randomized controlled trials (RCTs) we aimed to assess if ICG could also reduce risk of AL in rectal cancer surgery.

METHOD

PubMed, Scopus, CINAHL and Cochrane databases were searched for RCTs assessing the effect of intraoperative ICG on the incidence of AL of the colorectal anastomosis. Pooled relative risk (RR) and pooled risk difference (RD) were obtained using models with random effects. Risk of bias was evaluated with the Rob2 tool and the quality of evidence was assessed using the GRADE Pro tool.

RESULTS

Four RCTs were included for analysis, with a total of 1510 patients (743 controls and 767 ICG patients). The rate of AL was 9% in the ICG group (69/767) and 13.9% (103/743) in the control group (p = 0.003, RR -0.5, 95% CI -0.827 to -0.172, heterogeneity test 0%, p = 0.460). The RD in terms of incidence of AL was significantly decreased by 4.51% (p = 0.031, 95% CI -0.086 to -0.004, heterogeneity test 28%, p = 0.182) when using ICG.

CONCLUSION

Our meta-analysis suggested that use of ICG during rectal cancer surgery could reduce the rate of AL.

Consensus conference statement on fluorescence-guided surgery (FGS) ESSO course on fluorescence-guided surgery

BACKGROUND

Fluorescence-guided surgery (FGS) has emerged as an innovative technique with promising applications in various surgical specialties. However, clinical implementation is hampered by limited availability of evidence-based reference work supporting the translation towards standard-of-care use in surgical practice. Therefore, we developed a consensus statement on current applications of FGS.

METHODS

During an international FGS course, participants anonymously voted on 36 statements. Consensus was defined as agreement ≥70% with participation grade of ≥80%. All participants of the questionnaire were stratified for user and handling experience within five domains of applicability (lymphatics & lymph node imaging; tissue perfusion; biliary anatomy and urinary tracts; tumor imaging in colorectal, HPB, and endocrine surgery, and quantification and (tumor-) targeted imaging). Results were pooled to determine consensus for each statement within the respective sections based on the degree of agreement.

RESULTS

In total 43/52 (81%) course participants were eligible as voting members for consensus, comprising the expert panel (n = 12) and trained users (n = 31). Consensus was achieved in 17 out of 36 (45%) statements with highest level of agreement for application of FGS in tissue perfusion and biliary/urinary tract visualization (71% and 67%, respectively) and lowest within the tumor imaging section (0%).

CONCLUSIONS

FGS is currently established for tissue perfusion and vital structure imaging. Lymphatics & lymph node imaging in breast cancer and melanoma are evolving, and tumor tissue imaging holds promise in early-phase trials. Quantification and (tumor-)targeted imaging are advancing toward clinical validation. Additional research is needed for tumor imaging due to a lack of consensus.

Undertaking Studies Within A Trial to evaluate recruitment and retention strategies for randomised controlled trials: lessons learnt from the PROMETHEUS research programme

Background

Randomised controlled trials ('trials') are susceptible to poor participant recruitment and retention. Studies Within A Trial are the strongest methods for testing the effectiveness of strategies to improve recruitment and retention. However, relatively few of these have been conducted.

Objectives

PROMoting THE Use of Studies Within A Trial aimed to facilitate at least 25 Studies Within A Trial evaluating recruitment or retention strategies. We share our experience of delivering the PROMoting THE Use of Studies Within A Trial programme, and the lessons learnt for undertaking randomised Studies Within A Trial.

Design

A network of 10 Clinical Trials Units and 1 primary care research centre committed to conducting randomised controlled Studies Within A Trial of recruitment and/or retention strategies was established. Promising recruitment and retention strategies were identified from various sources including Cochrane systematic reviews, the Study Within A Trial Repository, and existing prioritisation exercises, which were reviewed by patient and public members to create an initial priority list of seven recruitment and eight retention interventions. Host trial teams could apply for funding and receive support from the PROMoting THE Use of Studies Within A Trial team to undertake Studies Within A Trial. We also tested the feasibility of undertaking co-ordinated Studies Within A Trial, across multiple host trials simultaneously.

Setting

Clinical trials unit-based trials recruiting or following up participants in any setting in the United Kingdom were eligible.

Participants

Clinical trials unit-based teams undertaking trials in any clinical context in the United Kingdom.

Interventions

Funding of up to £5000 and support from the PROMoting THE Use of Studies Within A Trial team to design, implement and report Studies Within A Trial.

Main outcome measures

Number of host trials funded.

Results

Forty-two Studies Within A Trial were funded (31 host trials), across 12 Clinical Trials Units. The mean cost of a Study Within A Trial was £3535. Twelve Studies Within A Trial tested the same strategy across multiple host trials using a co-ordinated Study Within A Trial design, and four used a factorial design. Two recruitment and five retention strategies were evaluated in more than one host trial. PROMoting THE Use of Studies Within A Trial will add 18% more Studies Within A Trial to the Cochrane systematic review of recruitment strategies, and 79% more Studies Within A Trial to the Cochrane review of retention strategies. For retention, we found that pre-notifying participants by card, letter or e-mail before sending questionnaires was effective, as was the use of pens, and sending personalised text messages to improve questionnaire response. We highlight key lessons learnt to guide others planning Studies Within A Trial, including involving patient and public involvement partners; prioritising and selecting strategies to evaluate and elements to consider when designing a Study Within A Trial; obtaining governance approvals; implementing Studies Within A Trial, including individual and co-ordinated Studies Within A Trials; and reporting Study Within A Trials.

Limitations

The COVID-19 pandemic negatively impacted five Studies Within A Trial, being either delayed (n = 2) or prematurely terminated (n = 3).

Conclusions

PROMoting THE Use of Studies Within A Trial significantly increased the evidence base for recruitment and retention strategies. When provided with both funding and practical support, host trial teams successfully implemented Studies Within A Trial.

Future work

Future research should identify and target gaps in the evidence base, including widening Study Within A Trial uptake, undertaking more complex Studies Within A Trial and translating Study Within A Trial evidence into practice.

Study registration

All Studies Within A Trial in the PROMoting THE Use of Studies Within A Trial programme had to be registered with the Northern Ireland Network for Trials Methodology Research Study Within A Trial Repository.

Funding

This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: 13/55/80) and is published in full in Health Technology Assessment; Vol. 28, No. 2. See the NIHR Funding and Awards website for further award information.

Blood Perfusion Assessment by Indocyanine Green Fluorescence Imaging for Minimally Invasive Rectal Cancer Surgery (EssentiAL trial): A Randomized Clinical Trial

OBJECTIVE

The aim of the present randomized controlled trial was to evaluate the superiority of indocyanine green fluorescence imaging (ICG-FI) in reducing the rate of anastomotic leakage in minimally invasive rectal cancer surgery.

BACKGROUND

The role of ICG-FI in anastomotic leakage in minimally invasive rectal cancer surgery is controversial according to the published literature.

METHODS

This randomized, open-label, phase 3, trial was performed at 41 hospitals in Japan. Patients with clinically stage 0-III rectal carcinoma less than 12 cm from the anal verge, scheduled for minimally invasive sphincter-preserving surgery were preoperatively randomly assigned to receive a blood flow evaluation by ICG-FI (ICG+ group) or no blood flow evaluation by ICG-FI (ICG- group). The primary endpoint was the anastomotic leakage rate (grade A+B+C, expected reduction rate of 6%) analyzed in the modified intention-to-treat population.

RESULTS

Between December 2018 and February 2021, a total of 850 patients were enrolled and randomized. After the exclusion of 11 patients, 839 were subject to the modified intention-to-treat population (422 in the ICG+ group and 417 in the ICG- group). The rate of anastomotic leakage (grade A+B+C) was significantly lower in the ICG+ group (7.6%) than in the ICG- group (11.8%) (relative risk, 0.645; 95% confidence interval 0.422-0.987; P =0.041). The rate of anastomotic leakage (grade B+C) was 4.7% in the ICG+ group and 8.2% in the ICG- group ( P =0.044), and the respective reoperation rates were 0.5% and 2.4% ( P =0.021).

CONCLUSIONS

Although the actual reduction rate of anastomotic leakage in the ICG+ group was lower than the expected reduction rate and ICG-FI was not superior to white light, ICG-FI significantly reduced the anastomotic leakage rate by 4.2%.

Lymphatic flow mapping during colon cancer surgery using indocyanine green fluorescence imaging

With the development of surgical technology, indocyanine green (ICG) fluorescence navigation systems may be useful in various areas of colorectal surgery, including tumor location confirmation, bowel perfusion, ureter identification, and lymph node mapping. This review provides an overview of the current status of ICG-based navigation surgery in colorectal surgery, emphasizing its role in lymphatic flow mapping. This state-of-the-art approach will allow for appropriate oncological surgeries in the field of colorectal cancer and improve the patient's prognosis.

Quantification of indocyanine green near-infrared fluorescence bowel perfusion assessment in colorectal surgery

BACKGROUND

Indocyanine green near-infrared fluorescence bowel perfusion assessment has shown its potential benefit in preventing anastomotic leakage. However, the surgeon's subjective visual interpretation of the fluorescence signal limits the validity and reproducibility of the technique. Therefore, this study aimed to identify objective quantified bowel perfusion patterns in patients undergoing colorectal surgery using a standardized imaging protocol.

METHOD

A standardized fluorescence video was recorded. Postoperatively, the fluorescence videos were quantified by drawing contiguous region of interests (ROIs) on the bowel. For each ROI, a time-intensity curve was plotted from which perfusion parameters (n = 10) were derived and analyzed. Furthermore, the inter-observer agreement of the surgeon's subjective interpretation of the fluorescence signal was assessed.

RESULTS

Twenty patients who underwent colorectal surgery were included in the study. Based on the quantified time-intensity curves, three different perfusion patterns were identified. Similar for both the ileum and colon, perfusion pattern 1 had a steep inflow that reached its peak fluorescence intensity rapidly, followed by a steep outflow. Perfusion pattern 2 had a relatively flat outflow slope immediately followed by its plateau phase. Perfusion pattern 3 only reached its peak fluorescence intensity after 3 min with a slow inflow gradient preceding it. The inter-observer agreement was poor-moderate (Intraclass Correlation Coefficient (ICC): 0.378, 95% CI 0.210-0.579).

CONCLUSION

This study showed that quantification of bowel perfusion is a feasible method to differentiate between different perfusion patterns. In addition, the poor-moderate inter-observer agreement of the subjective interpretation of the fluorescence signal between surgeons emphasizes the need for objective quantification.

Impact of powered circular stapler on anastomotic leak after anastomosis to the rectum: a propensity score matched study

PURPOSE

The aim of the present study is to assess the impact of Echelon Circular™ powered stapler (PCS) on left-sided colorectal anastomotic leaks and to compare results to conventional circular staplers (CCS).

METHODS

A single center cohort study was carried out on 552 consecutive patients, who underwent laparoscopic colorectal resection and anastomosis to the rectum between December 2017 and September 2022. Patients who underwent powered circular anastomosis to the rectum were matched to those who had a conventional stapled anastomosis using a propensity score matching. Main outcomes were anastomotic leak (AL) rate, anastomotic bleeding, and postoperative outcomes.

RESULTS

After adjusting cases with propensity score matching, two new groups of patients were generated: 145 patients in the PCS and 145 in the CCS. The two groups were homogeneous with respect to demographics and comorbidities on admission. Overall, AL occurred in 21 (7.3%) patients. No significant differences were observed with respect to AL (5.5% in PCS vs 9% in CCS; p = 0.66), fistula severity (p = 0.60) or reoperation rate (p = 0.65) in the two groups in study. A higher rate of anastomotic bleeding was observed in the CCS vs PCS (5.5% vs 0.7%, p = 0.03). At univariate analysis performed after propensity score matching, stapler diameter ≥ 31mm and age ≥ 70 years were the only variable significantly associated with anastomotic leak (p = 0.001 and p = 0.031; respectively).

CONCLUSIONS

The powered circular stapler has no impact on AL, while it could affect bleeding rate at the anastomotic site.

Total Neoadjuvant Treatment for Locally Advanced Rectal Cancer Patients: Where Do We Stand?

The therapeutic landscape in locally advanced rectal cancer (LARC) has undergone a significant paradigm shift in recent years with the rising adoption of total neoadjuvant treatment (TNT). This comprehensive approach entails administering chemotherapy and radiation therapy before surgery, followed by optional adjuvant chemotherapy. To establish and deliver the optimal tailored treatment regimen to the patient, it is crucial to foster collaboration among a multidisciplinary team comprising healthcare professionals from various specialties, including medical oncology, radiation oncology, surgical oncology, radiology, and pathology. This review aims to provide insights into the current state of TNT for LARC and new emerging strategies to identify potential directions for future research and clinical practice, such as circulating tumor-DNA, immunotherapy in mismatch-repair-deficient tumors, and nonoperative management.

Fluorescence-guided surgery: comprehensive review

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Is ICG essential in all colorectal surgery? A 3-year experience in a single center: a cohort study

INTRODUCTION AND OBJECTIVES

Indocyanine green (ICG) was introduced as a promising diagnostic tool to provide real-time assessment of intestinal vascularization. Nevertheless, it remains unclear whether ICG could reduce the rate of postoperative AL. The objective of this study is to assess its usefulness and to determine in which patients is most useful and would benefit the most from the use of ICG for intraoperative assessment of colon perfusion.

METHODS

A retrospective cohort study was conducted in a single center, including all patients who underwent colorectal surgery with intestinal anastomosis between January 2017 and December 2020. The results of patients in whom ICG was used prior to bowel transection were compared with the results of the patients in whom this technique was not used. Propensity score matching (PSM) was employed to compare groups with and without ICG.

RESULTS

A total of 785 patients who underwent colorectal surgery were included. The operations performed were right colectomies (35.0%), left colectomies (48.3%), and rectal resections (16.7%). ICG was used in 280 patients. The mean time since the infusion of ICG until detection of fluorescence in the colon wall was 26.9 ± 1.2 s. The section line was modified in 4 cases (1.4%) after ICG due to a lack of perfusion in the chosen section line. Globally, a non-statistically significant increase in anastomotic leak rate was observed in the group without ICG (9.3% vs. 7.5%; p = 0.38). The result of the PSM was a coefficient of 0.026 (CI - 0.014 to 0.065, p = 0.207).

CONCLUSIONS

ICG is a safe and useful tool to assess the perfusion of the colon prior to performing the anastomosis in colorectal surgery. However, in our experience, it did not significantly lower the anastomotic leakage rate.

Clinical application of machine learning and computer vision to indocyanine green quantification for dynamic intraoperative tissue characterisation: how to do it

INTRODUCTION

Indocyanine green (ICG) quantification and assessment by machine learning (ML) could discriminate tissue types through perfusion characterisation, including delineation of malignancy. Here, we detail the important challenges overcome before effective clinical validation of such capability in a prospective patient series of quantitative fluorescence angiograms regarding primary and secondary colorectal neoplasia.

METHODS

ICG perfusion videos from 50 patients (37 with benign (13) and malignant (24) rectal tumours and 13 with colorectal liver metastases) of between 2- and 15-min duration following intravenously administered ICG were formally studied (clinicaltrials.gov: NCT04220242). Video quality with respect to interpretative ML reliability was studied observing practical, technical and technological aspects of fluorescence signal acquisition. Investigated parameters included ICG dosing and administration, distance-intensity fluorescent signal variation, tissue and camera movement (including real-time camera tracking) as well as sampling issues with user-selected digital tissue biopsy. Attenuating strategies for the identified problems were developed, applied and evaluated. ML methods to classify extracted data, including datasets with interrupted time-series lengths with inference simulated data were also evaluated.

RESULTS

Definable, remediable challenges arose across both rectal and liver cohorts. Varying ICG dose by tissue type was identified as an important feature of real-time fluorescence quantification. Multi-region sampling within a lesion mitigated representation issues whilst distance-intensity relationships, as well as movement-instability issues, were demonstrated and ameliorated with post-processing techniques including normalisation and smoothing of extracted time-fluorescence curves. ML methods (automated feature extraction and classification) enabled ML algorithms glean excellent pathological categorisation results (AUC-ROC > 0.9, 37 rectal lesions) with imputation proving a robust method of compensation for interrupted time-series data with duration discrepancies.

CONCLUSION

Purposeful clinical and data-processing protocols enable powerful pathological characterisation with existing clinical systems. Video analysis as shown can inform iterative and definitive clinical validation studies on how to close the translation gap between research applications and real-world, real-time clinical utility.

Quantitative perfusion assessment using indocyanine green during surgery - current applications and recommendations for future use

PURPOSE

Incorrect assessment of tissue perfusion carries a significant risk of complications in surgery. The use of near-infrared (NIR) fluorescence imaging with Indocyanine Green (ICG) presents a possible solution. However, only through quantification of the fluorescence signal can an objective and reproducible evaluation of tissue perfusion be obtained. This narrative review aims to provide an overview of the available quantification methods for perfusion assessment using ICG NIR fluorescence imaging and to present an overview of current clinically utilized software implementations.

METHODS

PubMed was searched for clinical studies on the quantification of ICG NIR fluorescence imaging to assess tissue perfusion. Data on the utilized camera systems and performed methods of quantification were collected.

RESULTS

Eleven software programs for quantifying tissue perfusion using ICG NIR fluorescence imaging were identified. Five of the 11 programs have been described in three or more clinical studies, including Flow® 800, ROIs Software, IC Calc, SPY-Q™, and the Quest Research Framework®. In addition, applying normalization to fluorescence intensity analysis was described for two software programs.

CONCLUSION

Several systems or software solutions provide a quantification of ICG fluorescence; however, intraoperative applications are scarce and quantification methods vary abundantly. In the widespread search for reliable quantification of perfusion with ICG NIR fluorescence imaging, standardization of quantification methods and data acquisition is essential.

Intraluminal Anastomotic Assessment Using Indocyanine Green Near-Infrared Imaging for Left-Sided Colonic and Rectal Resections: a Systematic Review

BACKGROUND

Indocyanine green fluorescence angiography (ICG-FA) has been used in colorectal surgery to assess anastomotic perfusion and reduce the risks of anastomotic leaks. The main objective of this paper is to review the data on the transanal application of ICG-FA for the intraluminal assessment of colorectal anastomosis.

METHODS

A literature search was conducted for articles published between 2011 and 2021 using PubMed and Cochrane databases, related to the application of ICG for the intraluminal assessment of colorectal anastomosis. Original scientific manuscripts, review articles, meta-analyses, and case reports were considered eligible.

RESULTS

A total of 305 studies have been identified. After abstract screening for duplicates, 285 articles remained. Of those, 271 were not related to the topic of interest, 4 were written in a language other than English, and 4 had incomplete data. Six articles remained for the final analysis. The intraluminal assessment of colorectal anastomosis with ICG-FA is feasible, safe, and may reduce the incidence of leaks.

CONCLUSION

The intraluminal assessment of anastomotic perfusion via ICG-FA may be a promising novel application of ICG technology. More data is needed to support this application further to reduce leak rates after colorectal surgery, and future randomized clinical trials are awaited.

Early and late anastomotic leak after colorectal surgery: A systematic review of the literature

The aim of this study was to review and to assess the quality of the scientific articles regarding early and late anastomotic leak (AL) after colorectal surgery and their risk factors. An electronic systematic search for articles on Colorectal Surgery, AL and its timing was undertaken using the MEDLINE database via PubMed, Cochrane and Embase. The selected articles were thoroughly reviewed and assessed for methodological quality using a validated methodology quality score (MINCIR score). This review was registered in the PROSPERO registry under ID: CRD42022303012. 9 articles were finally reviewed in relation to the topic of early and late anastomotic leak. There is a lack of consensus regarding the exact cut-off in time to define early and late anastomotic leak, but it is clear that they are two differentiated entities. The first, occurring in relation to technical factors; whereas the latter, is related to impaired healing.

Indocyanine green fluorescence imaging during laparoscopic rectal cancer surgery could reduce the incidence of anastomotic leakage: a single institutional retrospective cohort study

BACKGROUND

There is insufficient evidence on whether indocyanine green (ICG) fluorescence angiography can reduce the incidence of anastomotic leakage (AL). This retrospective cohort study aimed to evaluate the effect of ICG fluorescence angiography on AL rates in laparoscopic rectal cancer surgery at a single institution.

METHODS

Patients who underwent laparoscopic low anterior resection or intersphincteric resection with ICG fluorescence angiography (ICG group; n = 73) and patients who underwent a similar surgical procedure for rectal cancer without ICG fluorescence (non-ICG group; n = 114) were enrolled consecutively in this study. ICG fluorescence angiography was performed prior to transection of the proximal colon, and anastomosis was performed with sufficient perfusion using ICG fluorescence imaging. AL incidence was compared between both groups, and the risk factors for AL were analyzed.

RESULTS

AL occurred in 3 (4.1%) and 14 (12.3%) patients in the ICG and non-ICG groups, respectively. In the ICG group, the median perfusion time from ICG injection was 34 s, and 5 patients (6.8%) required revision of the proximal transection line. None of the patients requiring revision of the proximal transection line developed AL. In univariate analysis, longer operating time (odds ratio: 2.758; 95% confidence interval: 1.023-7.624) and no implementation of ICG fluorescence angiography (odds ratio: 3.266; 95% confidence interval: 1.038-11.793) were significant factors associated with AL incidence, although the creation of a diverting stoma or insertion of a transanal tube was insignificant.

CONCLUSION

ICG fluorescence angiography was associated with a significant reduction in AL during laparoscopic rectal cancer surgery. Changes in the surgical plan due to ICG fluorescence visibility may help improve the short-term outcomes of patients with rectal cancer.

Deconstructing mastery in colorectal fluorescence angiography interpretation

INTRODUCTION

Indocyanine green fluorescence angiography (ICGFA) is commonly used in colorectal anastomotic practice with limited pre-training. Recent work has shown that there is considerable inconsistency in signal interpretation between surgeons with minimal or no experience versus those consciously invested in mastery of the technique. Here, we deconstruct the fluorescence signal patterns of expert-annotated surgical ICGFA videos to understand better their correlation and combine this with structured interviews to ascertain whether such interpretative capability is conscious or unconscious.

METHODS

For fluorescence signal analysis, expert-annotated ICGFA videos (n = 24) were quantitatively interrogated using a boutique intensity tracker (IBM Research) to generate signal time plots. Such fluorescence intensity data were examined for inter-observer correlation (Intraclass Correlation Coefficients, ICC) at specific curve milestones: the maximum fluorescence signal (Fmax), the times to both achieve this maximum (Tmax), as well as half this maximum (T1/2max) and the ratio between these (T1/2/Tmax). Formal tele-interview with contributing experts (n = 6) was conducted with the narrative transcripts being thematically mapped, plotted, and qualitatively analyzed.

RESULTS

Correlation by mathematical measures was excellent (ICC0.9-1.0) for Fmax, Tmax, and T1/2max (0.95, 0.938, and 0.925, respectively) and moderate (0.5-0.75) for T1/2/Tmax (0.729). While all experts narrated a deliberate viewing strategy, their specific dynamic signal appreciation differed in the manner of description.

CONCLUSION

Expert ICGFA users demonstrate high correlation in mathematical measures of their signal interpretation although do so tacitly. Computational quantification of expert behavior can help develop the necessary lexicon and training sets as well as computer vision methodology to better exploit ICGFA technology.

Use of fluorescence imaging and indocyanine green during colorectal surgery: Results of an intercontinental Delphi survey

BACKGROUND

Fluorescence imaging with indocyanine green is increasingly being used in colorectal surgery to assess anastomotic perfusion, and to detect sentinel lymph nodes.

METHODS

In this 2-round, online, Delphi survey, 35 international experts were asked to vote on 69 statements pertaining to patient preparation and contraindications to fluorescence imaging during colorectal surgery, indications, technical aspects, potential advantages/disadvantages, and effectiveness versus limitations, and training and research. Methodological steps were adopted during survey design to minimize risk of bias.

RESULTS

More than 70% consensus was reached on 60 of 69 statements, including moderate-strong consensus regarding fluorescence imaging's value assessing anastomotic perfusion and leak risk, but not on its value mapping sentinel nodes. Similarly, although consensus was reached regarding most technical aspects of its use assessing anastomoses, little consensus was achieved for lymph-node assessments. Evaluating anastomoses, experts agreed that the optimum total indocyanine green dose and timing are 5 to 10 mg and 30 to 60 seconds pre-evaluation, indocyanine green should be dosed milligram/kilogram, lines should be flushed with saline, and indocyanine green can be readministered if bright perfusion is not achieved, although how long surgeons should wait remains unknown. The only consensus achieved for lymph-node assessments was that 2 to 4 injection points are needed. Ninety-six percent and 100% consensus were reached that fluorescence imaging will increase in practice and research over the next decade, respectively.

CONCLUSION

Although further research remains necessary, fluorescence imaging appears to have value assessing anastomotic perfusion, but its value for lymph-node mapping remains questionable.

A Narrative Review of the Usefulness of Indocyanine Green Fluorescence Angiography for Perfusion Assessment in Colorectal Surgery

Anastomotic leakage is one of the most dreaded complications of colorectal surgery and is strongly associated with tissue perfusion. Indocyanine green fluorescence angiography (ICG-FA) using indocyanine green and near-infrared systems is an innovative technique that allows the visualization of anastomotic perfusion. Based on this information on tissue perfusion status, surgeons will be able to clearly identify colorectal segments with good blood flow for safer colorectal anastomosis. The results of several clinical trials indicate that ICG-FA may reduce the risk of AL in colorectal resection; however, the level of evidence is not high, as several other studies have failed to demonstrate a reduction in the risk of AL. Several large-scale RCTs are currently underway, and their results will determine whether ICG-FA is, indeed, useful. The major limitation of the current ICG-FA evaluation method, however, is that it is subjective and based on visual assessment by the surgeon. To complement this, the utility of objective evaluation methods for fluorescence using quantitative parameters is being investigated. Promising results have been reported from several clinical trials, but all trials are preliminary owing to their small sample size and lack of standardized protocols for quantitative evaluation. Therefore, appropriately standardized, high-quality, large-scale studies are warranted.

Evaluation of inter-user variability in indocyanine green fluorescence angiography to assess gastric conduit perfusion in esophageal cancer surgery

Indocyanine Green Fluorescence Angiography (ICGFA) has been deployed to tackle malperfusion-related anastomotic complications. This study assesses variations in operator interpretation of pre-anastomotic ICGFA inflow in the gastric conduit. Utilizing an innovative online interactive multimedia platform (Mindstamp), esophageal surgeons completed a baseline opinion-practice questionnaire and proceeded to interpret, and then digitally assign, a distal transection point on 8 ICGFA videos of esophageal resections (6 Ivor Lewis, 2 McKeown). Annotations regarding gastric conduit transection by ICGFA were compared between expert users versus non-expert participants using ImageJ to delineate longitudinal distances with Shapiro Wilk and t-tests to ascertain significance. Expert versus non-expert correlation was assessed via Intraclass Correlation Coefficients (ICC). Thirty participants (13 consultants, 6 ICGFA experts) completed the study in all aspects. Of these, a high majority (29 participants) stated ICGFA should be used routinely with most (21, including 5/6 experts) stating that 11-50 cases were needed for competency in interpretation. Among users, there were wide variations in dosing (0.05-3 mg/kg) and practice impact. Agreement regarding ICGFA video interpretation concerning transection level among experts was 'moderate' (ICC = 0.717) overall but 'good' (ICC = 0.871) among seven videos with Leave One Out (LOO) exclusion of the video with highest disagreement. Agreement among non-experts was moderate (ICC = 0.641) overall and in every subgroup including among consultants (ICC = 0.626). Experts choose levels that preserved more gastric conduit length versus non-experts in all but one video (P = 0.02). Considerable variability exists with ICGFA interpretation and indeed impact. Even adept users may be challenged in specific cases. Standardized training and/or computerized quantitative fluorescence may help better usage.

Trans-Anastomotic Drainage Tube Placement After Hand-Sewn Anastomosis in Patients Undergoing Intersphincteric Resection for Low Rectal Cancer: An Alternative Drainage Method

Anastomotic leakage (AL) is a common complication after intersphincteric resection (ISR). It significantly reduces quality of life and causes great distress to patients. Although traditional drainage (e.g., anal and pelvic catheters) may reduce the impact of AL to some extent, their role in reducing the incidence of AL remains controversial. In this study, we developed a novel drainage technique involving the placement of drainage tubes through the gap between sutures during handsewn anastomosis, to reduce the occurrence of anastomotic leakage. We retrospectively analyzed 34 consecutive patients who underwent intersphincteric resection requiring handsewn anastomosis between February 1, 2017, and January 1, 2021. Patients were classified into the trans-anastomotic drainage tube group (TADT, n = 14) and the non-TADT group (n = 20) based on whether trans-anastomotic tube placement was performed. The incidence of postoperative complications, such as AL, was compared between the two groups, and anal function of patients at 1-year post-ISR was evaluated. Six cases of AL occurred in the non-TADT group, while none occurred in the TADT group; this difference was statistically significant (p=0.031). The TADT group also had a shorter hospital stay (p=0.007). There were no other significant intergroup differences in operation time, blood loss, pain score, anastomotic stenosis, intestinal obstruction, or incidence of wound infection. In the 30 patients (88.2%) evaluated for anal function, there were no significant intergroup differences in stool frequency, urgency, daytime/nocturnal soiling, Wexner incontinence score, or Kirwan grading. Taken together, trans-anastomotic tube placement is a novel drainage method that may reduce AL after ISR requiring handsewn anastomosis and without adversely affecting anal function.

The use of fluorescence angiography to assess bowel viability in the acute setting: an international, multi-centre case series

Introduction

Assessing bowel viability can be challenging during acute surgical procedures, especially regarding mesenteric ischaemia. Intraoperative fluorescence angiography (FA) may be a valuable tool for the surgeon to determine whether bowel resection is necessary and to define the most appropriate resection margins. The aim of this study is to report on FA use in the acute setting and to judge its impact on intraoperative decision making.

Materials and methods

This is a multi-centre, retrospective case series of patients undergoing emergency abdominal surgery between February 2016 and 2021 in three general/colorectal units where intraoperative FA was performed to assess bowel viability. Primary endpoint was change of management after the FA assessment.

Results

A total of 93 patients (50 males, 66.6 ± 19.2 years, ASA score ≥ III in 85%) were identified and studied. Initial surgical approach was laparotomy in 66 (71%) patients and laparoscopy in 27 (29% and seven, 26% conversions). The most common aetiologies were mesenteric ischaemia (n = 42, 45%) and adhesional/herniae-related strangulation (n = 41, 44%). In 50 patients a bowel resection was performed. Overall rates of anastomosis after resection, reoperation and 30-day mortality were 48% (n = 24/50, one leak), 12% and 18%, respectively. FA changed management in 27 (29%) patients. In four patients (4% overall), resection was avoided and in 21 (23%) extra bowel length was preserved (median 50 cm of bowel saved, IQR 28–98) although three patients developed further ischaemia. FA prompted extended resection (median of 20 cm, IQR 10–50 extra bowel) in six (6%) patients.

Conclusion

Intraoperative use of FA impacts surgical decisions regarding bowel resection for intestinal ischaemia, potentially enabling bowel preservation in approximately one out of four patients. Prospective studies are needed to optimize the best use of this technology for this indication and to determine standards for the interpretation of FA images and the potential subsequent need for second-look surgeries.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00464-022-09136-7.

Comprehensive testing of colorectal anastomosis: results of prospective observational cohort study

BACKGROUND

Anastomotic leakage remains one of the most threatening complications in colorectal surgery. Intraoperative testing of anastomosis may reduce the postoperative anastomotic leakage rates. This study aimed to investigate a novel comprehensive intraoperative colorectal anastomosis testing technique to detect the failure of the anastomosis construction and to reduce the risk of postoperative leak.

METHODS

This multi-centre prospective cohort pilot study included 60 patients who underwent colorectal resection with an anastomosis at or below 15 cm from the anal verge. Comprehensive trimodal testing consisted of indocyanine green fluorescence angiography, tension testing, air-leak, and methylene blue leak tests to evaluate the perfusion, tension, and mechanical integrity of the anastomosis.

RESULTS

Ten (16.7%) patients developed an anastomotic leakage. Trimodal test was positive in 16 (26.6%) patients and the operative plan was changed for all of them. Diverting ileostomy was performed in 14 (87.5%) patients. However, two (12.5%) patients still developed clinically significant anastomotic leakage (Grade B). Forty-four (73.4%) patients had a negative trimodal test, preventive ileostomy was performed in 19 (43.2%), and five (11.4%) patients had clinically significant anastomotic leakage (Grade B and C).

CONCLUSION

Trimodal testing identifies anastomoses with initial technical failure where reinforcement of anastomosis or diversion can lead to an acceptable rate of anastomotic leakage. Identification of well-performed anastomosis could allow a reduction of ileostomy rate by two-fold. However, anastomotic leakage rate remains high in technically well-performed anastomoses.

Impact of change in the surgical plan based on indocyanine green fluorescence angiography on the rates of colorectal anastomotic leak: a systematic review and meta-analysis

BACKGROUND

In the present study, patients with colorectal anastomoses that were assessed with indocyanine green (ICG) fluorescence angiography (FA) were compared to patients who had only white light visual inspection of their anastomosis. The impact of change in surgical plan guided by ICG-FA on anastomotic leak (AL) rates was assessed.

METHODS

PubMed, Scopus, Web of Science, and Cochrane Central Register of Controlled Trials were queried for eligible studies. Studies included were comparative cohort studies and randomized trials that compared perfusion assessment of colorectal anastomosis with ICG-FA and inspection under white light. Main outcome measures were change in surgical plan guided by ICG-FA and rates of AL. Risk of bias was assessed using RoB-2 and ROBINS-1 tools. Differences between the two groups in categorical and continuous variables were expressed as odds ratio (OR) with 95% confidence interval (CI) and weighted mean difference.

RESULTS

This systematic review included 27 studies comprising 8786 patients (48.5% males). Using ICG-FA was associated with significantly lower odds of AL (OR 0.452; 95% CI 0.366-0.558) and complications (OR 0.747; 95% CI 0.592-0.943) than the control group. The weighted mean rate of change in surgical plan based on ICG-FA was 9.6% (95% CI 7.3-11.8) and varied from 0.64% to 28.75%. A change in surgical plan was associated with significantly higher odds of AL (OR 2.73; 95% CI 1.54-4.82).

LIMITATIONS

Technical heterogeneity due to using different dosage of ICG and statistical heterogeneity in operative time and complication rates.

CONCLUSION

Assessment of colorectal anastomoses with ICG-FA is likely to be associated with lower odds of anastomotic leak than is traditional white light assessment. Change in plan based on ICG-FA may be associated with higher odds of AL. PROSPERO registration number: CRD42021235644.

Fundamentals and developments in fluorescence-guided cancer surgery

Fluorescence-guided surgery using tumour-targeted imaging agents has emerged over the past decade as a promising and effective method of intraoperative cancer detection. An impressive number of fluorescently labelled antibodies, peptides, particles and other molecules related to cancer hallmarks have been developed for the illumination of target lesions. New approaches are being implemented to translate these imaging agents into the clinic, although only a few have made it past early-phase clinical trials. For this translational process to succeed, target selection, imaging agents and their related detection systems and clinical implementation have to operate in perfect harmony to enable real-time intraoperative visualization that can benefit patients. Herein, we review key aspects of this imaging cascade and focus on imaging approaches and methods that have helped to shed new light onto the field of intraoperative fluorescence-guided cancer surgery with the singular goal of improving patient outcomes.

Risk Factors and Preventive Measures for Anastomotic Leak in Colorectal Cancer

Anastomotic leak (AL) represents one of the most detrimental complications after colorectal surgery. The patient-related factors and surgery-related factors leading to AL have been identified in previous studies. Through early identification and timely adjustment of risk factors, preventive measures can be taken to reduce potential AL. However, there are still many problems associated with AL. The debate about preventive measures such as preoperative mechanical bowel preparation (MBP), intraoperative drainage, and surgical scope also continues. Recently, the gut microbiota has received more attention due to its important role in various diseases. Although the underlying mechanisms of gut microbiota on AL have not been validated completely, new strategies that manipulate intrinsic mechanisms are expected to prevent and treat AL. Moreover, laboratory examinations for AL prediction and methods for blood perfusion assessment are likely to be promoted in clinical practice. This review outlines possible risk factors for AL and suggests some preventive measures in terms of patient, surgery, and gut microbiota.

The use of mesenchymal stem cells in animal models for gastrointestinal anastomotic leak: A systematic review

AIM

Anastomotic leak is the most feared complication of gastrointestinal surgery. Mesenchymal stem cell technology is used clinically to promote wound healing; however, the safety and efficacy of this technology on anastomotic healing has yet to be defined. The aim of this study was to investigate whether mesenchymal stem cells confer any benefit when applied to animal models for gastrointestinal anastomotic leak, identify the methodology and how efficacy is assessed.

METHODS

The MEDLINE, EMBASE, WebofScience and Cochrane Library databases were interrogated between 1 January1947 to 1 May 2020. All studies where mesenchymal stem cells were applied to laboratory animal leak models to demonstrate a healing effect were considered. All experimental and histological outcomes were examined. Compliance to ARRIVE and current International Consensus was assessed.

RESULTS

A total of 1205 studies were screened. Twelve studies reported on 438 gastrointestinal anastomoses in four species using 11 models; seven in the colon. No studies utilised a model with a known leak rate. Significant variance was observed in histological outcomes with efficacy demonstrated in five out of 12 studies. One study demonstrated a benefit in leak rate. Colorectal studies had a greater median ARRIVE compliance, 60.8% (IQR 63.2-64.5) compared to noncolorectal 45.4% (IQR 43.8-49.0).

CONCLUSIONS

Mesenchymal stem cell delivery to an animal anastomosis is safe and feasible. Use may confer benefit but findings are currently limited to surrogate histological outcomes. There is consistency in outcome measures reported but variance in how this is assessed. Poor compliance to ARRIVE but good compliance to current international consensus in leak models of the colon was observed.

A novel fluorescent c-met targeted imaging agent for intra-operative colonic tumour mapping: Translation from the laboratory into a clinical trial

BACKGROUND

The c-Met protein is overexpressed in many gastrointestinal cancers. We explored EMI-137, a novel c-Met targeting fluorescent probe, for application in fluorescence-guided colon surgery, in HT-29 colorectal cancer (CRC) cell line and an in vivo murine model.

METHODS

HT-29 SiRNA transfection confirmed specificity of EMI-137 for c-Met. A HT-29 CRC xenograft model was developed in BALB/c mice, EMI-137 was injected and biodistribution analysed through in vivo fluorescent imaging. Nine patients, received a single intravenous EMI-137 bolus (0.13 mg/kg), 1-3 h before laparoscopic-assisted colon cancer surgery (NCT03360461). Tumour and LN fluorescence was assessed intraoperatively and correlated with c-Met expression in eight samples by immunohistochemistry.

FINDINGS

c-Met expression HT-29 cells was silenced and imaged with EMI-137. Strong EMI-137 uptake in tumour xenografts was observed up to 6 h post-administration. At clinical trial, no serious adverse events related to EMI-137 were reported. Marked background fluorescence was observed in all participants, 4/9 showed increased tumour fluorescence over background; 5/9 had histological LN metastases; no fluorescent LN were detected intraoperatively. All primary tumours (8/8) and malignant LN (15/15) exhibited high c-Met protein expression.

INTERPRETATION

EMI-137, binds specifically to the human c-Met protein, is safe, and with further refinement, shows potential for application in fluorescence-guided surgery.

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.

Role of near-infrared fluorescence in colorectal surgery

Near-infrared fluorescence (NIRF) is a technique of augmented reality that, when applied in the operating theatre, allows the colorectal surgeon to visualize and assess bowel vascularization, to identify lymph nodes draining a cancer site and to identify ureters. Herein, we review the literature regarding NIRF in colorectal surgery.

Predictive and Diagnostic Biomarkers of Anastomotic Leakage: A Precision Medicine Approach for Colorectal Cancer Patients

Development of an anastomotic leak (AL) following intestinal surgery for the treatment of colorectal cancers is a life-threatening complication. Failure of the anastomosis to heal correctly can lead to contamination of the abdomen with intestinal contents and the development of peritonitis. The additional care that these patients require is associated with longer hospitalisation stays and increased economic costs. Patients also have higher morbidity and mortality rates and poorer oncological prognosis. Unfortunately, current practices for AL diagnosis are non-specific, which may delay diagnosis and have a negative impact on patient outcome. To overcome these issues, research is continuing to identify AL diagnostic or predictive biomarkers. In this review, we highlight promising candidate biomarkers including ischaemic metabolites, inflammatory markers and bacteria. Although research has focused on the use of blood or peritoneal fluid samples, we describe the use of implantable medical devices that have been designed to measure biomarkers in peri-anastomotic tissue. Biomarkers that can be used in conjunction with clinical status, routine haematological and biochemical analysis and imaging have the potential to help to deliver a precision medicine package that could significantly enhance a patient's post-operative care and improve outcomes. Although no AL biomarker has yet been validated in large-scale clinical trials, there is confidence that personalised medicine, through biomarker analysis, could be realised for colorectal cancer intestinal resection and anastomosis patients in the years to come.

ICG fluorescence imaging in colorectal surgery: a snapshot from the ICRAL study group

Background

Fluorescence-guided visualization is a recently proposed technology in colorectal surgery. Possible uses include evaluating perfusion, navigating lymph nodes and searching for hepatic metastases and peritoneal spread. Despite the absence of high-level evidence, this technique has gained considerable popularity among colorectal surgeons due to its significant reliability, safety, ease of use and relatively low cost. However, the actual use of this technique in daily clinical practice has not been reported to date.

Methods

This survey was conducted on April 2020 among 44 centers dealing with colorectal diseases and participating in the Italian ColoRectal Anastomotic Leakage (iCral) study group. Surgeons were approximately equally divided based on geographical criteria from multiple Italian regions, with a large proportion based in public (89.1%) and nonacademic (75.7%) centers. They were invited to answer an online survey to snapshot their current behaviors regarding the use of fluorescence-guided visualization in colorectal surgery. Questions regarding technological availability, indications and techniques, personal approaches and feelings were collected in a 23-item questionnaire.

Results

Questionnaire replies were received from 37 institutions and partially answered by 8, as this latter group of centers do not implement fluorescence technology (21.6%). Out of the remaining 29 centers (78,4%), fluorescence is utilized in all laparoscopic colorectal resections by 72.4% of surgeons and only for selected cases by the remaining 27.6%, while 62.1% of respondents do not use fluorescence in open surgery (unless the perfusion is macroscopically uncertain with the naked eye, in which case 41.4% of them do). The survey also suggests that there is no agreement on dilution, dosing and timing, as many different practices are adopted based on personal judgment. Only approximately half of the surgeons reported a reduced leak rate with fluorescence perfusion assessment, but 65.5% of them strongly believe that this technique will become a minimum requirement for colorectal surgery in the future.

Conclusion

The survey confirms that fluorescence is becoming a widely used technique in colorectal surgery. However, both the indications and methods still vary considerably; furthermore, the surgeons' perceptions of the results are insufficient to consider this technology essential. This survey emphasizes the need for further research to reach recommendations based on solid scientific evidence.

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.

Clinical translation and implementation of optical imaging agents for precision image-guided cancer surgery

INTRODUCTION

The field of tumor-specific fluorescence-guided surgery has seen a significant increase in the development of novel tumor-targeted imaging agents. Studying patient benefit using intraoperative fluorescence-guided imaging for cancer surgery is the final step needed for implementation in standard treatment protocols. Translation into phase III clinical trials can be challenging and time consuming. Recent studies have helped to identify certain waypoints in this transition phase between studying imaging agent efficacy (phase I-II) and proving patient benefit (phase III).

TRIAL INITIATION

Performing these trials outside centers of expertise, thus involving motivated clinicians, training them, and providing feedback on data quality, increases the translatability of imaging agents and the surgical technique. Furthermore, timely formation of a trial team which oversees the translational process is vital. They are responsible for establishing an imaging framework (camera system, imaging protocol, surgical workflow) and clinical framework (disease stage, procedure type, clinical research question) in which the trial is executed. Providing participating clinicians with well-defined protocols with the aim to answer clinically relevant research questions within the context of care is the pinnacle in gathering reliable trial data.

OUTLOOK

If all these aspects are taken into consideration, tumor-specific fluorescence-guided surgery is expected be of significant value when integrated into the diagnostic work-up, surgical procedure, and follow-up of cancer patients. It is only by involving and collaborating with all stakeholders involved in this process that successful clinical translation can occur.

AIM

Here, we discuss the challenges faced during this important translational phase and present potential solutions to enable final clinical translation and implementation of imaging agents for image-guided cancer surgery.

Evidence of negative pressure therapy for anastomotic leak: a systematic review

BACKGROUND

Anastomotic leak (AL) is a devastating complication. Several new treatment options are available, endoluminal negative pressure therapy is one. The aims of this systematic review are; to report success rates and stoma closure rates following endoluminal negative pressure therapy in colorectal AL patients.

METHODS

A systematic review of MEDLINE, PubMed, Cochrane and Embase databases from inception to June 2018. Search limits were; English language, humans, sample >5 and >18 years. Search terms were Endospong* OR Endo-spong* OR Endo spong* OR Endoluminal negative pressure OR Endoluninal vac* OR Vacuum assisted OR negative pressure. Combined with colon OR rectum OR colorect* AND anastomotic leak OR leak*.

RESULTS

Twenty articles met inclusion criteria. There were 334 patients. Reported success rates ranged from 60% to 100%. However, success definition varied considerably. The most widely used definition was endoscopic assessment of residual cavity size, but this also varied from 0.5 cm to 3 cm. Stoma closure rates were only reported in 11 studies and ranged from 31% to 100%. Complication rates were reported in 13 studies (65%). The most common was on-going sepsis.

CONCLUSIONS

Included studies suggest that 60-100% of ALs heal with endoluminal negative pressure therapy. However, results from this review need to be interpreted with caution because of the variable definition of success. A more objective assessment of success may be stoma closure but this is only reported in 60% of studies. Further studies are needed to assess the benefit of negative pressure therapy in anastomotic leaks.

[Evidence of indocyanine green fluorescence in robotically assisted colorectal surgery : What is the status?]

BACKGROUND

Indocyanine green (ICG) fluorescence imaging is increasingly being used in various areas of abdominal surgery. The constant improvement in the technology enables easy intraoperative use and progressively influences operative decision-making, also in robotically assisted colorectal surgery.

OBJECTIVE

Summation of current evidence on the use of ICG fluorescence imaging in robotically assisted colorectal surgery.

MATERIAL AND METHODS

The assessment of evidence is based on a comprehensive literature search (PubMed).

RESULTS

First individual studies (feasibility, case matched, prospective cohort, multicenter phase II, single center randomized controlled study/trial) showed a significant reduction in the incidence of anastomotic leakage (AL) after colorectal anastomosis through the use of ICG fluorescence angiography (FA, 9.1% vs. 16.3%; p = 0.04). First feasibility studies demonstrated lymph node detection or navigation as well as ureter visualization.

CONCLUSION

The ICG-FA reliably detects tissue perfusion, quickly and effectively with few side effects. It can influence intraoperative decision-making and reduce AL rates. In addition, patients may be offered more precise tumor therapy via ICG sentinel lymph node (SLN) detection and lateral pelvic lymph node (LPN) mapping and navigation. Iatrogenic lesions, such as ureteral injuries can be sufficiently prevented by appropriate visualization; however, valid data in order to be able to derive standardized operative consequences require further convincing multicenter, randomized controlled trials (mRCT).

Inter-user variation in the interpretation of near infrared perfusion imaging using indocyanine green in colorectal surgery

INTRODUCTION

Despite increasing endorsement of near-infrared perfusion assessment using indocyanine green (ICG) during colorectal surgery, little work has yet been done regarding learning curve and interobserver variation most especially on surgical video reflective of real-world usage.

METHODS

Surgeons with established expertise in ICG usage were invited to participate in the study along with others without such experience including trainees. All participants completed an opinion questionnaire and interpreted video presentations of fluorescence angiograms in a variety of colorectal case scenarios. An interactive video platform (Mindstamp) enabled dynamic annotation. Statistical analysis of data was performed using Kruskal-Wallis and Mann-Whitney testing as well as Intraclass Correlation Coefficients and Fleiss Multi-rater Kappa Scoring.

RESULTS

Forty participants (six experts) completed questionnaire data and provided judgement of 14 videos (nine showing proximal colonic transection site perfusion, four showing completed anastomoses and one an acutely strangulated bowel). 70% felt > 10 cases were needed for competency in use with the majority of experts advocating > 50 (p < 0.05). Overall agreement among experts was "good" for videos showing colonic transection perfusion (versus "moderate" among in-experts) with experts clustering more distally. In contrast, there was no interpretation concordance among experts or in-experts when judging ICG perfusion sufficiency on a yes/no basis.

CONCLUSION

Significant experience is recommended before reliance on ICG perfusion angiograms. ICG fluorescence assessment is prone to variable interpretation and influenced by experience and, perhaps, knowledge of preassessment operative steps suggesting a role for objective flow analysis with artificial intelligence methods as the next phase of this technology.

Clinical role of fluorescence imaging in colorectal surgery - an updated review

INTRODUCTION

Colorectal surgery has markedly advanced due to the introduction of laparoscopic and robotic surgery. During the past 20 years, these two modalities have been further enhanced by fluorescence imaging.

AREAS COVERED

This article will review the common and novel uses for fluorophores in colorectal surgery, including tissue perfusion for anastomotic creation, ureter identification, lymphatic mapping, and tumor localization.

EXPERT OPINION

The versatility of this technology permeates through many aspects of colorectal procedures. The white light spectrum has historically been the only available modality to visualize tissue perfusion, tumor implants, and structures including the ureters and lymph nodes. The ability of the near-infrared spectrum to penetrate biologic tissues allows the identification of these structures with injection of fluorophores. The two most common intravenously utilized fluorophores are methylene blue and indocyanine green. Additionally, novel tumor marker-specific fluorophores are being investigated for purposes of cancer detection.