Methylene blue fluorescence of the ureter during colorectal surgery

Assessment of the Quality of Patient-Oriented Internet Information on Fluorescence Imaging in Surgery

BACKGROUND

In the digital age, patients are increasingly turning to the Internet to seek medical information to aid in their decision-making process before undergoing medical treatments. Fluorescence imaging is an emerging technological tool that holds promise in enhancing intra-operative decision-making during surgical procedures. This study aims to evaluate the quality of patient information available online regarding fluorescence imaging in surgery and assesses whether it adequately supports informed decision-making.

METHOD

The term "patient information on fluorescence imaging in surgery" was searched on Google. The websites that fulfilled the inclusion criteria were assessed using 2 scoring instruments. DISCERN was used to evaluate the reliability of consumer health information. QUEST was used to assess authorship, tone, conflict of interest and complementarity.

RESULTS

Out of the 50 websites identified from the initial search, 10 fulfilled the inclusion criteria. Only two of these websites were updated in the last two years. The definition of fluorescence imaging was stated in only 50% of the websites. Although all websites mentioned the benefits of fluorescence imaging, none mentioned potential risks. Assessment by DISCERN showed that 30% of the websites were rated low and 70% were rated moderate. With QUEST, the websites demonstrated an average score of 62.5%.

CONCLUSION

This study highlights the importance of providing patients with accurate and balanced information about medical technologies and procedures they may undergo. Fluorescence imaging in surgery is a promising technology that can potentially improve surgical outcomes. However, patients need to be well-informed about its benefits and limitations in order to make informed decisions about their healthcare.

Preventing iatrogenic ureteral injury in colorectal surgery: a comprehensive and systematic review of the last 2 decades of literature and future perspectives

Iatrogenic ureteral injury (IUI) during colorectal surgery is a rare complication but related to a serious burden of morbidity. This comprehensive and systematic review aims to provide a critical overview of the most recent literature about IUI prevention techniques in colorectal surgery. We performed a comprehensive and systematic review of studies published from 2000 to 2022 and assessed the use of techniques for ureteral injury prevention and intraoperative localization. 26 publications were included, divided into stent-based (prophylactic/lighted ureteral stent and near-infrared fluorescent ureteral catheter [PUS/LUS/NIRFUC]) and fluorescent dye (FD) groups. Costs, the percentage and number of IUIs detected, reported limitations, complication rates and other outcome points were compared. The IUI incidence rate ranged from 0 to 1.9% (mean 0.5%) and 0 to 1.2% (mean 0.3%) in the PUS/LUS/NIRFUC and FD groups, respectively. The acute kidney injury (AKI) and urinary tact infection (UTI) incidence rate ranged from 0.4 to 32.6% and 0 to 17.3%, respectively, in the PUS/LUS/NIRFUC group and 0-15% and 0-6.3%, respectively, in the FD group. Many other complications were also compared and descriptively analyzed (length-of-stay, mortality, etc.). These techniques appear to be feasible and safe in select patients with a high risk of IUI, but the delineation of reliable guidelines for preventing IUI will require more randomized controlled trials.

Iatrogenic ureteral injury: What should the digestive surgeon know?

PURPOSE OF THE STUDY

Iatrogenic ureteral injury (IUI) is a rare but formidable complication of any abdominal or pelvic surgery. The aim of this study was to describe the epidemiology of IUI in colorectal surgery in the Basse-Normandie region over the period 2004-2022, as well as to review the literature on the management of this complication.

MATERIALS AND METHODS

This multicenter retrospective analysis of clinical data (medical records and operative reports) concerned 22 patients (13 men and 9 women) who suffered an IUI during colorectal surgery between 2004 and 2022. Ureteral resections for oncological purposes and endoluminal instrumental injuries (post-ureteroscopy) were excluded from the study. We also carried out a review of the literature concerning the incidence of IUI in colorectal surgery.

RESULTS

The incidence of IUI was 0.27% over the study period (22 ureteral injuries out of 8129 colorectal procedures). Colorectal cancer and sigmoid diverticulitis were the dominant surgical indications (85% of cases). Proctectomy and left colectomy were the most performed resection procedures (75% of cases). Surgery was scheduled in 68% of cases. The approach was open laparotomy in 59% and laparoscopy in 41% of cases. The IUI involved the left ureter in 63% of cases and the pelvic ureter in 77% of cases. Conservative endoscopic treatment by insertion of a double-J catheter stent had a success rate of 87.5%. Surgical repairs consisting of re-implantation techniques and uretero-ureteral anastomosis had a success rate of 75%. The nephrectomy rate was 13.6% (3/22) and the mortality rate 9% (2/22). A literature review identified sixteen studies, where the incidence of IUI varied from 0.1 to 4.5%.

FINDINGS

IUI occurring during colorectal surgery is a rare occurrence but remain a formidable complication. No means of prevention has proven its effectiveness to date, but guidance devices using illuminated ureteral catheters or dyes seem to constitute a promising approach. Injuries to the left pelvic ureter are the most common, and the majority can be treated endoscopically if diagnosed early.

2023 WSES guidelines for the prevention, detection, and management of iatrogenic urinary tract injuries (IUTIs) during emergency digestive surgery

Iatrogenic urinary tract injury (IUTI) is a severe complication of emergency digestive surgery. It can lead to increased postoperative morbidity and mortality and have a long-term impact on the quality of life. The reported incidence of IUTIs varies greatly among the studies, ranging from 0.3 to 1.5%. Given the high volume of emergency digestive surgery performed worldwide, there is a need for well-defined and effective strategies to prevent and manage IUTIs. Currently, there is a lack of consensus regarding the prevention, detection, and management of IUTIs in the emergency setting. The present guidelines, promoted by the World Society of Emergency Surgery (WSES), were developed following a systematic review of the literature and an international expert panel discussion. The primary aim of these WSES guidelines is to provide evidence-based recommendations to support clinicians and surgeons in the prevention, detection, and management of IUTIs during emergency digestive surgery. The following key aspects were considered: (1) effectiveness of preventive interventions for IUTIs during emergency digestive surgery; (2) intra-operative detection of IUTIs and appropriate management strategies; (3) postoperative detection of IUTIs and appropriate management strategies and timing; and (4) effectiveness of antibiotic therapy (including type and duration) in case of IUTIs.

Simultaneous fluorescence imaging of bowel perfusion and ureter delineation using methylene blue: a demonstration in a porcine model

BACKGROUND

Intraoperative near-infrared fluorescence imaging (NIRF) with preoperative optical dye administration is a promising technique for quick and easy intraoperative visualization of the ureter and for an improved, real-time assessment of intestinal perfusion. During colorectal surgery, there is a need for simultaneous non-invasive ureteral imaging and bowel perfusion assessment, using one single camera system. The purpose of this study is to investigate the feasibility of simultaneous intestinal perfusion and ureteral imaging using a single commercially available NIRF imaging system.

METHODS

Six Landrace pigs underwent laparotomy under general anesthesia in this experiment. An intravenous (IV) dose of 0.2 mg/kg indocyanine green (ICG) was given to assess bowel perfusion. Two pairs received a methylene blue (MB) iv injection of 0.75, 0.50 or 0.25 mg/kg respectively to investigate ureteral visualization. Quest Spectrum Fluorescence Camera (Quest Medical Imaging, Middenmeer, The Netherlands) was used for NIRF imaging.

RESULTS

Ureter visualization and bowel perfusion under NIRF imaging was achieved in all animals. All ureters were visible after five to ten minutes and remained clearly visible until the end of every experiment (120-420 min). A mixed model analysis did not show any significant differences neither between the three groups nor over time. Importantly, we demonstrated that bowel perfusion could be visualized with methylene blue (MB) as well. We observed no interference between ICG and MB and a faster washout of MB.

CONCLUSION

We successfully demonstrated simultaneous fluorescence angiography with ICG and ureteral imaging with MB in the same surgical procedure, with the same commercially available NIRF imaging equipment. More importantly, we showed that the use MB is adequate for bowel perfusion assessment and ureter visualization with this NIRF imaging system. Besides, MB showed an earlier washout time, which can be clinical beneficial as a repeated dye injection may be necessary during a surgical procedure.

Evaluation of the Utilization of Near-Infrared Fluorescent Contrast Agent ASP5354 for In Vivo Ureteral Identification in Renal Diseases Using Rat Models of Gentamicin-Induced Acute Kidney Injury

ASP5354 was recently developed as a near-infrared fluorescence (NIRF) contrast agent for intraoperative ureteral identification, and its use has been evaluated in healthy animals. However, the utilization of ASP5354 for ureteral identification has not been evaluated in animals with renal injury. In this study, we assessed the application of ASP5354 for ureteral imaging using rat models of gentamicin-induced mild, moderate, and severe acute kidney injury (AKI), using a clinically available NIRF detection system. NIRF was detected in the abdominal cavity and ureters after laparotomy, and the efficiency of ASP5354 was evaluated based on the NIRF signal intensity over 60 min. After the intravenous injection of ASP5354 into rats with mild or moderate AKI, the ureters were clearly imaged at a high ratio of NIRF intensity in the ureter to that in the tissues around the ureter. Six days after intravenous injection, the use of ASP5354 in rats with moderate AKI did not affect the biochemical kidney functions or histopathological conditions of the kidney tissues, as compared to those with no injection of ASP5354. In rats with severe AKI, ureteral imaging was not effective due to the relatively strong NIRF expression in the tissues around the ureters. These data indicate that ASP5354 holds potential as a contrast agent for intraoperative ureteral identification in patients with limited renal injury.

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.

Simultaneous, Multi-Channel, Near-Infrared Fluorescence Visualization of Mesenteric Lymph Nodes Using Indocyanine Green and Methylene Blue: A Demonstration in a Porcine Model

Near-infrared fluorescence (NIRF) image-guided surgery is a useful tool that can help reduce perioperative complications and improve tissue recognition. Indocyanine green (ICG) dye is the most frequently used in clinical studies. ICG NIRF imaging has been used for lymph node identification. However, there are still many challenges in lymph node identification by ICG. There is increasing evidence that methylene blue (MB), another clinically applicable fluorescent dye, can also be useful in the intraoperative fluorescence-guided identification of structures and tissues. We hypothesized that MB NIRF imaging could be used for lymph node identification. The aim of this study was to evaluate the feasibility of intraoperative lymph node fluorescence detection using intravenously (IV) administered MB and compare it to ICG via a camera that has two dedicated near-infrared (NIR) channels. Three pigs were used in this study. ICG (0.2 mg/kg) was administered via a peripheral venous catheter followed by immediate administration of MB (0.25 mg/kg). NIRF images were acquired as video recordings at different time points (every 10 min) over an hour using the QUEST SPECTRUM^® 3 system (Quest Medical Imaging, Middenmeer, The Netherlands), which has two dedicated NIR channels for simultaneous intraoperative fluorescence guidance. The 800 nm channel was used to capture ICG fluorescence and the 700 nm channel was used for MB. The target (lymph nodes and small bowel) and the background (vessels-free field of the mesentery) were highlighted as the regions of interest (ROIs), and corresponding fluorescence intensities (FI) from these ROIs were measured. The target-to-background ratio (TBR) was then computed as the mean FI of the target minus the mean FI of the background divided by the mean FI of the background. In all included animals, a clear identification of lymph nodes was achieved at all time points. The mean TBR of ICG in lymph nodes and small bowel was 4.57 ± 1.00 and 4.37 ± 1.70, respectively for the overall experimental time. Regarding MB, the mean TBR in lymph nodes and small bowel was 4.60 ± 0.92 and 3.27 ± 0.62, respectively. The Mann-Whitney U test of the lymph node TBR/small bowel TBR showed that the TBR ratio of MB was statistically significantly higher than ICG. The fluorescence optical imaging technology used allows for double-wavelength assessment. This feasibility study proves that lymph nodes can be discriminated using two different fluorophores (MB and ICG) with different wavelengths. The results suggest that MB has a promising potential to be used to detect lymphatic tissue during image-guided surgery. Further preclinical trials are needed before clinical translation.

Dye encapsulation and one-pot synthesis of microporous-mesoporous zeolitic imidazolate frameworks for CO2 sorption and adenosine triphosphate biosensing

One-pot co-precipitation of target molecules e.g. organic dyes and the synthesis of a crystal containing microporous-mesoporous regimes of zeolitic imidazolate frameworks-8 (ZIF-8) are reported. The synthesis method can be used for cationic (rhodamine B (RhB), methylene blue (MB)), and anionic (methyl blue (MeB)) dyes. The crystal growth of the ZIF-8 crystals takes place via an intermediate phase of zinc hydroxyl nitrate (Zn₅(OH)₈(NO₃)₂) nanosheets that enabled the adsorption of the target molecules i.e., RhB, MB, and MeB into their layers. The dye molecules play a role during crystal formation. The successful encapsulation of the dye molecules was proved via diffuse reflectance spectroscopy (DRS) and electrochemical measurements e.g., cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS). The materials were investigated for carbon dioxide (CO₂) adsorption and adenosine triphosphate (ATP) biosensing. ZIF-8, RhB@ZIF-8, MB@ZIF-8, and MeB@ZIF-8 offered CO₂ adsorption capacities of 0.80, 0.84, 0.85, and 0.53 mmol g^-1, respectively. The encapsulated cationic molecules improved the adsorption performance compared to anionic molecules inside the crystal. The materials were also tested as a fluorescent probe for ATP biosensing. The simple synthesis procedure offered new materials with tunable surface properties and the potential for multi-functional applications.

Prevention of ureteral injury during laparoscopic colorectal cancer surgery with horseshoe kidney using fluorescent ureteral catheters: a case report

BACKGROUND

Horseshoe kidney is one of the most common congenital renal fusion anomalies and is characterized by abnormalities in the position, rotation, vascular supply, and ureteral anatomy of the kidney. When performing surgery for colorectal cancer in patients with horseshoe kidneys, anatomical identification is important to avoid organ injuries. Several reports on surgery for colorectal cancer with horseshoe kidneys have described the usefulness of three-dimensional (3D) computed tomography (CT) angiography for detecting abnormalities in vascular supply. However, few reports have focused on the prevention of ureteral injury in surgery for colorectal cancer with horseshoe kidney, despite abnormalities in the ureteral anatomy. Here, we report a case in which laparoscopic sigmoid colon resection for sigmoid colon cancer with a horseshoe kidney was safely performed using fluorescent ureteral catheters.

CASE PRESENTATION

A 60-year-old Japanese man presented to our hospital testing positive for fecal occult blood. Colonoscopy revealed sigmoid colon cancer, and CT confirmed a horseshoe kidney. The 3D-CT angiography showed aberrant renal arteries from the aorta and right common iliac artery, and the left ureter passed across the front of the renal isthmus. A fluorescent ureteral catheter was placed in the left ureter before the surgery to prevent ureteral injury. Laparoscopic sigmoid colon resection with D3 lymph node dissection was performed. The fluorescent ureteral catheter enabled the identification of the left ureter that passed across the front of the renal isthmus and the safe mobilization of the descending and sigmoid colon from the retroperitoneum. The operative time was 214 min, with intraoperative bleeding of 25 mL. The patient's postoperative course was good: no complications arose and she was discharged on the seventh postoperative day.

CONCLUSION

In patients with horseshoe kidney, the use of fluorescent ureteral catheters and 3D-CT angiography enables safer laparoscopic surgery for colorectal cancer. We recommend the placement of fluorescent ureteral catheters in such surgeries to prevent ureteral injury.

Assessing the development status of intraoperative fluorescence imaging for anatomy visualisation, using the IDEAL framework

Objectives

Intraoperative fluorescence imaging is currently used in a variety of surgical fields for four main purposes: visualising anatomy, assessing tissue perfusion, identifying/localising cancer and mapping lymphatic systems. 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 used to visualise anatomical structures using the IDEAL framework, a framework designed to describe the stages of innovation in surgery and other interventional procedures.

Design

IDEAL staging based on a thorough literature review.

Setting

All publications on intraoperative fluorescence imaging for visualising anatomical structures reported in PubMed through 2020 were identified for five surgical procedures: cholangiography, hepatic segmentation, lung segmentation, ureterography and parathyroid identification.

Main outcome measures

The IDEAL stage of research evidence was determined for each of the five procedures using a previously described approach.

Results

225 articles (8427 cases) were selected for analysis. Current status of research evidence on fluorescence imaging was rated IDEAL stage 2a for ureterography and lung segmentation, IDEAL 2b for hepatic segmentation and IDEAL stage 3 for cholangiography and parathyroid identification. Enhanced tissue identification rates using fluorescence imaging relative to conventional white-light imaging have been documented for all five procedures by comparative studies including randomised controlled trials for cholangiography and parathyroid identification. Advantages of anatomy visualisation with fluorescence imaging for improving short-term and long-term postoperative outcomes also were demonstrated, especially for hepatobiliary surgery and (para)thyroidectomy. No adverse reactions associated with fluorescent agents were reported.

Conclusions

Intraoperative fluorescence imaging can be used safely to enhance the identification of anatomical structures, which may lead to improved postoperative outcomes. Overviewing current research knowledge using the IDEAL framework aids in designing further studies to develop fluorescence imaging techniques into an essential intraoperative navigation tool in each surgical field.

Computer-Assisted Differentiation between Colon-Mesocolon and Retroperitoneum Using Hyperspectral Imaging (HSI) Technology

Complete mesocolic excision (CME), which involves the adequate resection of the tumor-bearing colonic segment with “en bloc” removal of its mesocolon along embryological fascial planes is associated with superior oncological outcomes. However, CME presents a higher complication rate compared to non-CME resections due to a higher risk of vascular injury. Hyperspectral imaging (HSI) is a contrast-free optical imaging technology, which facilitates the quantitative imaging of physiological tissue parameters and the visualization of anatomical structures. This study evaluates the accuracy of HSI combined with deep learning (DL) to differentiate the colon and its mesenteric tissue from retroperitoneal tissue. In an animal study including 20 pig models, intraoperative hyperspectral images of the sigmoid colon, sigmoid mesentery, and retroperitoneum were recorded. A convolutional neural network (CNN) was trained to distinguish the two tissue classes using HSI data, validated with a leave-one-out cross-validation process. The overall recognition sensitivity of the tissues to be preserved (retroperitoneum) and the tissues to be resected (colon and mesentery) was 79.0 ± 21.0% and 86.0 ± 16.0%, respectively. Automatic classification based on HSI and CNNs is a promising tool to automatically, non-invasively, and objectively differentiate the colon and its mesentery from retroperitoneal tissue.

Fluorescent ureteral catheters in laparoscopic surgery for rectal cancer with invasion of the uterus: A case report

Introduction

Resection of the uterus is required in some cases of colorectal cancer with invasion of the uterus. Localisation of the ureters to prevent ureteral injuries is important during resection of advanced colorectal cancer and combined resection of the uterus.

Case presentation

We report a case of a woman in her 80s with rectal cancer with invasion of the uterus. She presented with appetite loss and lower abdominal pain. She was hospitalised after being diagnosed with intestinal obstruction due to rectal cancer. Colonoscopy revealed a tumor involving 100% of the circumference of the rectosigmoid colon, and imaging showed rectal cancer with invasion of the uterus and a giant uterine fibroid. Fluorescent ureteral catheters were placed bilaterally under cystoscopy, and laparoscopic anterior rectal resection, combined hysterectomy, and bilateral adnexectomy were performed 1 day later. Near-infrared visualisation of these catheters enabled safe release of the surrounding tissues from the uterus.

Clinical discussion

Surgical treatment of rectal cancer with invasion of the uterus is not standardised and requires more complicated procedures, which are associated with a high risk of ureteral injury. Fluorescent ureteral catheters allow visualisation of the course of the ureters without releasing them, thereby enabling safe surgery.

Conclusion

In fluorescence-guided surgery for rectal cancer, fluorescent ureteral catheters are particularly useful in patients with suspected invasion of other organs.

•T4b rectal cancer has higher risk of ureteral injury.

•Fluorescent ureteral catheter is visualised clearly via near-infrared light.

•Fluorescent ureteral catheter can be useful during surgery for T4b rectal cancer.

Methylene Blue Near-Infrared Fluorescence Imaging in Breast Cancer Sentinel Node Biopsy

Simple Summary

Currently the gold standard for sentinel node biopsy in breast cancer patients is radioactive nanocolloid and a blue dye. In the age of fluorescence guided surgery new fluorophores are used and methylene blue presents some fluorescent properties. This study is the first in a clinical series presenting the possible use of methylene blue as a fluorescent dye for the identification of sentinel nodes in breast cancer sentinel node biopsy. We presented a feasibility of this new method and also in additional experiments because of the quenching effect limitation, found possible dilution of methylene blue presenting improved fluorescence.

Abstract

Introduction: Fluorescence-based navigation for breast cancer sentinel node biopsy is a novel method that uses indocyanine green as a fluorophore. However, methylene blue (MB) also has some fluorescent properties. This study is the first in a clinical series presenting the possible use of MB as a fluorescent dye for the identification of sentinel nodes in breast sentinel node biopsy. Material and methods: Forty-nine patients with breast cancer who underwent sentinel node biopsy procedures were enrolled in the study. All patients underwent standard simultaneous injection of nanocolloid and MB. We visualized and assessed the sentinel nodes and the lymphatic channels transcutaneously, with and without fluorescence, and calculated the signal-to-background ratio (SBR). We also analyzed the corresponding fluorescence intensity of various dilutions of MB. Results: In twenty-three patients (46.9%), the location of the sentinel node, or the end of the lymphatic path, was visible transcutaneously. The median SBR for transcutaneous sentinel node location was 1.69 (range 1.66–4.35). Lymphatic channels were visible under fluorescence in 14 patients (28.6%) prior to visualization by the naked eye, with an average SBR of 2.01 (range 1.14–5.6). The sentinel node was visible under fluorescence in 25 patients (51%). The median SBR for sentinel node visualization with MB fluorescence was 2.54 (range 1.34–6.86). Sentinel nodes were visualized faster under fluorescence during sentinel node preparation. Factors associated with the rate of visualization included diabetes (p = 0.001), neoadjuvant chemotherapy (p = 0.003), and multifocality (p = 0.004). The best fluorescence was obtained using 40 μM (0.0128 mg/mL) MB, but we also observed a clinically relevant dilution range between 20 μM (0.0064 mg/mL) and 100 μM (0.032 mg/mL). Conclusions: For the first time, we propose the clinical usage of MB as a fluorophore for fluorescence-guided sentinel node biopsy in breast cancer patients. The quenching effect of the dye may be the reason for its poor detection rate. Our analysis of different concentrations of MB suggests a need for a detailed clinical analysis to highlight the practical usefulness of the dye.

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.

Fluorescence Imaging Using Methylene Blue Sentinel Lymph Node Biopsy in Melanoma

Introduction

Fluorescence imaging of sentinel node biopsy in melanoma is a novel method. Both indocyanine green (ICG) and methylene blue (MB) have fluorescent properties. The aim of this study was to present, for the first time in a clinical series of patients, the possible usage of MB as a fluorescent dye for sentinel node biopsy during surgery for melanoma.

Material and methods

Twenty patients with skin melanoma, who were candidates for sentinel node biopsy were enrolled in our study. All patients underwent simultaneous use of standard nanocolloid and blue dye. Transcutaneous visualization of the sentinel node, visualization of lymphatic channels as well as sentinel node fluorescent visualization were all measured. We also performed calculations of Signal to Background ratios (SBR).

Results

In 15% (3/20) of patients, the fluorescent sentinel node was visible through the skin. The median SBR for the sentinel node visualization by fluorescence was 3.15 (range, 2.7–3.5). Lymphatic channels were visible in lymphatic tissue via fluorescence before visualization by the naked eye in 4 patients (20%). The median SBR ratio was 3.69 (range, 2.7–4.2). Sentinel nodes were visible by fluorescence in 13 cases (65%). The median SBR ratio was 2.49 (range, 1.5–5.7). No factors were found to be associated with fluorescent MB visualization of a sentinel node during biopsy.

Conclusion

This is the first clinical study presenting the usefulness of fluorescent sentinel node biopsy in melanoma patients using MB as a fluorophore. Further studies are necessary to provide methods for its’ clinical implementation.

Image Navigation Surgery With the Fluorescent Ureteral Catheter of Recurrent Tumors in the Pelvic Cavity

INTRODUCTION

Ureteral injury during pelvic surgery is a serious complication that requires special attention. The fluorescent ureteral catheter near-infrared ray catheter sets are 6.0F catheters containing fluorescent substances along their length that can be recognized by a laparoscopic indocyanine green camera. We present our experience using a near-infrared ray catheter in 6 consecutive patients who underwent surgery for recurrent pelvic tumors.

TECHNIQUE

The near-infrared ray catheters were inserted into the bilateral ureters in all patients, with the exception of patient 5 (left unilateral), by urologists using a cystoscope with the same technique as that commonly used in placing ureteral stents under general anesthesia. A laparoscopic indocyanine green camera was adapted to identify the ureters. From February 2020 to July 2020, 6 consecutive patients with recurrent pelvic tumors underwent surgery using a near-infrared ray catheter. In 3 patients, recurrent tumors were detected in the pelvic cavity after surgery for colon cancer (1 patient each of peritoneal recurrence behind the seminal vesicles, lymph node metastasis on the residual superior rectal artery, and peritoneal recurrence at the peritoneal reflection). Two patients had postoperative local recurrences of rectal cancer. The last patient had a recurrence of cervical carcinoma invading the rectum.

RESULTS

All patients underwent surgery under ureteral image navigation using near-infrared ray catheter not only for ureter preservation during the operation (4 patients) but also for the combined resection of the ureter with recurrent tumors (2 patients). One patient experienced postoperative ureteral stenosis on postoperative day 21 that required a ureteral double J-stent placement in the left ureter.

CONCLUSION

Near-infrared ray catheter has the potential to reduce inadvertent periureteral dissection because the ureter can be identified before approaching it.

Multispectral Imaging Using Fluorescent Properties of Indocyanine Green and Methylene Blue in Colorectal Surgery-Initial Experience

Introduction: Image-guided surgery is becoming a new tool in colorectal surgery. Intraoperative visualisation of different structures using fluorophores helps during various steps of operations. In our report, we used two fluorophores—indocyanine green (ICG), and methylene blue (MB)—during different steps of colorectal surgery, using one camera system for two separate near-infrared wavelengths. Material and methods: Twelve patients who underwent complex open or laparoscopic colorectal surgeries were enrolled. Intravenous injections of MB and ICG at different time points were administered. Visualisation of intraoperative ureter position and fluorescent angiography for optimal anastomosis was performed. A retrospective analysis of patients treated in our departments during 2020 was performed, and data about ureter injury and anastomotic site complications were collected. Results: Intraoperative localisation of ureters with MB under fluorescent light was possible in 11 patients. The mean signal-to-background ratio was 1.58 ± 0.71. Fluorescent angiography before performing anastomosis using ICG was successful in all 12 patients, and none required a change in position of the planned colon resection for anastomosis. The median signal-to-background ratios was 1.25 (IQR: 1.22–1.89). Across both centres, iatrogenic injury of the ureter was found in 0.4% of cases, and complications associated with anastomosis was found in 5.5% of cases. Conclusions: Our study showed a substantial opportunity for using two different fluorophores in colorectal surgery, whereby the visualisation of one will not change the possible quantification analysis of the other. Using two separate dyes during one procedure may help in optimisation of the fluorescent properties of both dyes when using them for different applications. Visualisation of different structures by different fluorophores seems to be the future of image-guided surgery, and shows progress in optical technologies used in image-guided surgery.

Fluorescence Molecular Targeting of Colon Cancer to Visualize the Invisible

Colorectal cancer (CRC) is a common cause of cancer and cancer-related death. Surgery is the only curative modality. Fluorescence-enhanced visualization of CRC with targeted fluorescent probes that can delineate boundaries and target tumor-specific biomarkers can increase rates of curative resection. Approaches to enhancing visualization of the tumor-to-normal tissue interface are active areas of investigation. Nonspecific dyes are the most-used approach, but tumor-specific targeting agents are progressing in clinical trials. The present narrative review describes the principles of fluorescence targeting of CRC for diagnosis and fluorescence-guided surgery with molecular biomarkers for preclinical or clinical evaluation.

Laparoscopic surgery using 8 K ultra-high-definition technology: Outcomes of a phase II study

INTRODUCTION

Currently, laparoscopic surgery generally relies on 2 K high-definition image quality. The National Cancer Center Hospital, Olympus Corporation, and NHK Engineering System Inc. recently developed a new laparoscopic system with an 8 K ultra-high-definition (UHD) camera that provides images with a high-resolution, wide color range, high frame rate, and high dynamic range. This study aimed to investigate the effectiveness and safety of a new laparoscopic system which uses an 8 K UHD camera system (8K UHD system).

METHODS

This phase II study enrolled 23 patients with colon or rectosigmoid cancer who were indicated for radical resection with laparoscopic colectomy using the 8 K UHD system. The primary endpoint was the proportion of patients with ≥30 mL of intraoperative blood loss.

RESULTS

Of the 23 patients, 22 completed laparoscopic surgery with the 8 K UHD system. One patient was converted to the 2 K high-definition laparoscopic system due to technical difficulties with the 8 K UHD system during surgery. The median amount of intraoperative blood loss was 14 mL (range, 2-71 mL), and number of patients with intraoperative blood loss ≥30 mL was four (17.4%). None of the patients had >100 mL of intraoperative blood loss. No intraoperative complications were noted, and four (17.4%) patients developed postoperative complications. Pathological complete resection was achieved in all patients, and no conversion to open surgery was required.

CONCLUSIONS

Laparoscopic surgery using the 8 K UHD system appears to be both safe and effective. However, further refinements may be necessary to improve usability.

Fluorescent imaging for cancer therapy and cancer gene therapy

The translation of laboratory science into effective clinical cancer therapy is gaining momentum more rapidly than any other time in history. Understanding cancer cell-surface receptors, cancer cell growth, and cancer metabolic pathways has led to many promising molecular-targeted therapies and cancer gene therapies. These same targets may also be exploited for optical imaging of cancer. Theoretically, any antibody or small molecule targeting cancer can be labeled with bioluminescent or fluorescent agents. In the laboratory setting, fluorescence imaging (FI) and bioluminescence imaging (BLI) have long been used in preclinical research for quantification of tumor bulk, assessment of targeting of tumors by experimental agents, and discrimination between primary and secondary effects of cancer treatments. Many of these laboratory techniques are now moving to clinical trials. Imageable engineered fluorescent probes that are highly specific for cancer are being advanced. This will allow for the identification of tumors for staging, tracking novel therapeutic agents, assisting in adequate surgical resection, and allowing image-guided biopsies. The critical components of FI include (1) a fluorescent protein that is biologically safe, stable, and distinctly visible with a high target to background ratio and (2) highly sensitive optical detectors. This review will summarize the most promising optical imaging agents and detection devices for cancer clinical research and clinical care.

Fluorescence ureteral navigation during laparoscopic surgery for clinically suspected stage T4 colorectal cancer: A cohort study

BACKGROUND

Approximately 15% of patients with colorectal cancer present with locally advanced tumors (T4 stage). Laparoscopic surgery for stage T4 disease has not yet been established. The near-infrared ray catheter fluorescent ureteral catheter (NIRFUC) is a new device that uses near-infrared fluorescence resin. We examined the utility of fluorescence ureteral navigation (FUN) with the NIRFUC during laparoscopic surgery for stage T4 colorectal cancer.

MATERIALS AND METHODS

Patients with stage T4 colorectal cancer (n = 143, from January 2017 to March 2021) were divided into a T4FUN + group, in which the NIRFUC was used (n = 21), and a T4FUN- group, in which the NIRFUC was not used (n = 122). Short-term outcomes were compared between the groups. Next, the laparoscopic surgery rate and incidence of ureteral injury from January 2017 to March 2021 were compared between the T4FUN- group and the non-stage T4FUN- group (n = 434, from January 2017 to March 2021), in which fluorescence ureter navigation was not used.

RESULTS

Rectal cancer, stage T4b disease, and invasion into the urinary tract were observed more often in the T4FUN + group than in the T4FUN- group. In the comparisons of the T4FUN + versus T4FUN- groups, the operative time was 398 (161-1090) vs. 256 (93-839) minutes, the blood loss was 10 (1-710) vs. 25 (0-1360) ml, and the ratio of laparoscopic surgery to open surgery was 21:0 vs. 79:43. Postoperative complications (Clavien-Dindo grade ≥ III) were present in 2 (10%; 0 ureteral injury) patients in the T4FUN + group and 13 (11%; 2 ureteral injury) patients in the T4FUN- group. In the T4FUN + group, the operative time was longer (p < 0.0001), but the laparoscopic ratio was higher (p = 0.0002), and the blood loss volume and incidence of ureteral injury tended to be lower. In the comparisons of the T4FUN- versus non-stage T4FUN- groups, the ratio of laparoscopic surgery to open surgery was 79:43 vs. 384:50, the incidence of open conversion was 8 (6.6%) vs. 15 (3.5%), and the incidence of ureteral injury was 2 (1.6%) vs. 0 (0%). In the T4FUN- group, the open surgery rate (<0.0001), open conversion rate (p = 0.0205) and incidence of ureteral injury (p = 0.0478) were high, with a significant difference observed between the groups.

CONCLUSION

Patients with stage T4 disease have an increased risk of ureteral injury and are more likely to be converted to open surgery. FUN can help to safely increase the laparoscopic surgery rate while safely visualizing the ureter. FUN is recommended for laparoscopic surgery in patients with stage T4 colorectal cancer.

CLINICAL TRIAL REGISTRATION

Examination of fluorescence navigation for laparoscopic colorectal cancer surgery; Research Ethics Committee of the Kawaguchi Municipal Medical Center (Saitama, Japan) approval number: 2020-3. https://kawaguchi-mmc.org/wp-content/uploads/clinical research-r02.pdf.

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

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

Comprehensive Review of Fluorescence Applications in Gynecology

Since the introduction of indocyanine green (ICG) as a fluorophore in near-infrared imaging, fluorescence visualization has become an essential tool in many fields of surgery. In the field of gynecology, recent new applications have been proposed and found their place in clinical practice. Different applications in gynecology were investigated, subcategorized, and overviewed concerning surgical applications and available dyes. Specific applications in which fluorescence-guided surgery was implemented in gynecology are described in this manuscript—namely, sentinel node biopsy, mesometrium visualization, angiography of different organs, safety issues in pregnant women, ureters visualization, detection of peritoneal metastases, targeted fluorophores for cancer detection, fluorescent contamination hysterectomy, lymphography for lower limb lymphedema prevention, tumor margin detection, endometriosis, and metastases mapping. With evolving technology, further innovative research on the new applications of fluorescence visualization in cancer surgery may help to establish these techniques as standards of high-quality surgery in gynecology. However, more investigations are necessary in order to assess if these innovative tools can also be effective to improve patient outcomes and quality of life in different gynecologic malignancies.

New Technique of Laparoscopic Paraaortic Lymph Node Dissection for Colorectal Cancer Using Fluorescence Navigation

BACKGROUND/AIM

According to limited current reports, therapeutic paraaortic lymph node (PALN) dissection with intensive combined therapy for colorectal cancer improves prognosis in select patients. Laparoscopic PALN dissection is a difficult technique that has not yet been established. We applied this procedure using an intraoperative fluorescence navigation technique with a near-infrared ray catheter (NIRC™) fluorescent ureteral catheter (NIRFUC).

PATIENTS AND METHODS

We evaluated the utility of laparoscopic fluorescence navigation and the short-term outcomes of 6 patients undergoing laparoscopic PALN dissection.

RESULTS

There were 3 surgeries for synchronous metastasis and 3 surgeries for recurrent metastasis. The mean surgical duration, blood loss, and postoperative hospital stay were 677 (range=518-1,090) min, 7.5 (range=3-1,600) ml, and 14 (range=9-33) days, respectively. Postoperative complications (Clavien-Dindo grade >III) occurred in 1 case.

CONCLUSION

Dissection around the ureter was navigated with a NIRFUC. Fluorescence ureteral navigation facilitated completion of the complex laparoscopic PALN dissection procedure.

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.

Feasibility of injected indocyanine green for ureteral identification during robotic left-sided colorectal resections

BACKGROUND

Ureteral identification is essential to performing safe colorectal surgery. Injected immunofluorescence may aid with ureteral identification, but feasibility without ureteral catheterization is not well described.

METHODS

Case series of robotic colorectal resections where indocyanine green (ICG) injection with or without ureteral catheter placement was performed. Imaging protocol, time to ureteral identification, and factors impacting visualization are reported.

RESULTS

From 2019 to 2020, 83 patients underwent ureteral ICG injection, 20 with catheterization and 63 with injection only. Main indications were diverticulitis (52%) and cancer (36%). Median time to instill ICG was faster with injection alone than with catheter placement (4min vs 13.5min, p < 0.001). Median time [IQR] to right ureter (0.3 [0.01-1.2] min after robot docking) and left ureter (5.5 [3.1-8.8] min after beginning dissection) visualization was not different between injection alone and catheterization.

CONCLUSION

ICG injection alone is faster than with indwelling catheter placement and equally reliable at intraoperative ureteral identification.

Ureteral navigation using a fluorescent ureteral catheter during laparoscopic colorectal surgery

BACKGROUND

Ureteral injury is the most common urological complication of pelvic surgery, with a reported incidence during colon resection of 0.3-1.5%. Ureteral stenting is commonly performed preoperatively to prevent ureteral injury. Because tactile sensation is not reliable during laparoscopic surgery, the effect of the ureteral stent is considered limited. Recently, fluorescence imaging has been used in laparoscopic surgery. The Near-Infrared Ray Catheter (NIRC™) fluorescent ureteral catheter (NIRFUC) is a new catheter with built-in NIR fluorescent resin. This pilot study was performed to evaluate the utility of fluorescence ureteral navigation using the NIRFUC during laparoscopic colorectal surgery.

METHODS

We evaluated the intraoperative utility of the NIRFUC and the short-term outcomes in 20 patients treated with colorectal surgery at Kawaguchi Municipal Medical Center between February and July 2020. In all, 18 patients with malignant tumors and 2 patients with benign disease, i.e., a sigmoid colovesical fistula, were included. Ten patients developed preoperative intestinal obstruction. One patient experienced preoperative perforation. Nine patients developed preoperative peritumoral abscesses. Laparoscopic surgery was performed with the VISERA ELITE2 system.

RESULTS

In all cases, the ureters were very clearly identified as fluorescent without the need for dissection. In all cases, only a moment was required to identify the ureter by fluorescence observation. In all cases, R0 resection was performed. The mean surgical duration was 334 min (161-1014), the mean blood loss was 10 ml (1-500), and the mean postoperative hospital stay was 11 days (8-47). There were no cases of ureteral injury.

CONCLUSION

The NIRFUC was very clearly identified as fluorescent in a moment during surgery without dissection around the ureter. Fluorescence ureteral navigation using the NIRFUC may make colorectal surgery easier and facilitate completion of complex minimally invasive surgery, especially during surgery in patients with invasion of the surrounding tissue or a history of pelvic surgery or radiation.

Fluorescence imaging in colorectal surgery

BACKGROUND

Fluorescent imaging is an emerging technological tool that can guide surgeons during surgery by highlighting anatomical structures and pathology, and help with intraoperative decision making.

METHODS

A comprehensive review of published literature was performed using the search terms "fluorescence", "imaging" and "colorectal surgery" in PubMed. Only clinical trials that were published in English were included in this review. Ex vivo and animal studies were excluded.

RESULTS

This review demonstrates the use of fluorescence imaging in colorectal surgery in four areas: (1) assessment of tissue perfusion and vasculature; (2) assessment of tumour; (3) lymphatic drainage and (4) identification of the urinary tract. The most commonly used fluorescent dyes are nonspecific, such as indocyanine green and methylene blue, but there is increasing interest in the development of specific fluorescently labelled molecular markers.

CONCLUSION

Fluorescence imaging is a potentially useful tool for colorectal surgery. Early studies on fluorescence imaging have been promising but larger scale randomised controlled trials are warranted to demonstrate the effectiveness and benefits of using fluorescence imaging routinely. The development of molecular dyes that are specific to targets could significantly increase the potential use of fluorescence imaging during surgery.

Indocyanine green fluorescence-guided laparoscopic colorectal cancer surgery with prophylactic retrograde transileal conduit ureteral catheter placement after previous total cystectomy: a case report

BACKGROUND

Iatrogenic ureteral injury (UI) is a potentially serious complication of colorectal cancer surgery. Performing perioperative placement of ureteral stents or intraoperative fluorescence navigation surgery for the ureter using indocyanine green (ICG) has been employed as a method of preventing UI. However, transileal conduit stent placement has been considered challenging because it is difficult to identify the ureteral orifice due to the anatomical changes caused by a previous surgery. We report a case in which laparoscopic colectomy was safely performed using a combination of prophylactic transileal conduit ureteral catheter placement and intraoperative ICG fluorescence navigation surgery.

CASE PRESENTATION

A 75-year-old man presented to our hospital complaining of vomiting and abdominal distension. He had a history of open total cystectomy and ileal conduit urinary diversion 11 years prior to admission. Computed tomography confirmed colon dilation with fecal impaction from the ascending colon to the sigmoid colon and wall thickening in the sigmoid colon. Colonoscopy during the transanal ileus tube insertion revealed a Borrmann type II tumor with circumferential stenosis 10 cm distal to the junction between the descending colon and the sigmoid colon. The patient was diagnosed with colorectal ileus due to obstructive sigmoid colon cancer and underwent transanal ileus tube insertion. Severe intra-abdominal adhesions were expected due to the previous total cystectomy, and the left ureter was near the sigmoid colon tumor; therefore, prophylactic retrograde transileal conduit ureteral catheter placement was performed one day before the elective surgery. During the operation, 20 ml (5.0 × 10^-2 mg/ml) ICG was administered from the transileal conduit ureteral catheter, and ICG fluorescence of the ureter was observed in the retroperitoneum. Laparoscopic Hartmann's operation was successfully performed, confirming ureter fluorescence. The operation time was 231 min, with 5 mL of intraoperative bleeding. The ureteral catheter was removed 3 days after the operation. The patient's postoperative course was good with no complications, and he was discharged on postoperative day 7.

CONCLUSIONS

Prophylactic transileal conduit ureteral catheter placement and ICG fluorescence navigation surgery were effective in performing laparoscopic colorectal surgery with severe adhesions after urinary diversion.

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.

Methylene Blue-Current Knowledge, Fluorescent Properties, and Its Future Use

Methylene blue is a fluorescent dye discovered in 1876 and has since been used in different scientific fields. Only recently has methylene blue been used for intraoperative fluorescent imaging. Here, the authors review the emerging role of methylene blue, not only as a dye used in clinical practice, but also as a fluorophore in a surgical setting. We discuss the promising potential of methylene blue together with the challenges and limitations among specific surgical techniques. A literature review of PubMed and Medline was conducted based on the historical, current and future usage of methylene blue within the field of medicine. We reviewed not only the current usage of methylene blue, but we also tried to grasp its’ function as a fluorophore in five main domains. These domains include the near-infrared imaging visualization of ureters, parathyroid gland identification, pancreatic tumors imaging, detection of breast cancer tumor margins, as well as breast cancer sentinel node biopsy. Methylene blue is used in countless clinical procedures with a relatively low risk for patients. Usage of its fluorescent properties is still at an early stage and more pre-clinical, as well as clinical research, must be performed to fully understand its potentials and limitations.

Simultaneous multipurpose fluorescence imaging with IRDye® 800BK during laparoscopic surgery

BACKGROUND

IRDye® 800BK is a fluorophore, currently undergoing clinical translation, which has both biliary and renal clearance. To date, there is no description of a fluorophore, which can be simultaneously used for non-invasive, near-infrared fluorescence-based (NIRF) visualization of different structures and perfusion evaluation. The purpose of this study was to evaluate IRDye® 800BK for the simultaneous assessment of bowel perfusion, lymphography, ureter and bile duct delineation.

METHODS

Six pigs received a 0.15 mg/kg dye as a single bolus intravenous injection (IV). With the FLER (fluorescence-based enhanced reality) software, fluorescence intensity (FI) of 5 regions of interest (ROI) in an ischemic bowel loop was measured along with the time to reach the FI peak, and capillary lactate was measured from the same ROI, followed by the assessment of the ureters and bile ducts for a maximal duration of 180 min after dye administration. In 3 animals, the procedure was initiated via gastroscopic injection of a 0.6 mg (1 mg/mL) dye in the gastric submucosa followed by lymphography in a NIRF setting.

RESULTS

Excellent visualization of the ureters and bowel perfusion was obtained under NIRF imaging. Additionally, the bile duct and gastric lymph ducts and nodes were visualized. A positive correlation was found between the time to peak FI in the ischemic bowel loop and the corresponding capillary lactate levels (rho 0.59, p < 0.001).

CONCLUSION

In this study, we successfully demonstrated the simultaneous multipurpose IRDye® 800BK applicability during laparoscopic surgery. This fluorophore has the potential to become a powerful and versatile image-guided surgery tool.

A Near-Infrared Fluorescent Probe Coated with β-Cyclodextrin Molecules for Real-Time Imaging-Guided Intraoperative Ureteral Identification and Diagnosis

Although iatrogenic ureteral injury and its lack of recognition due to ureteral invisibility are serious incidents in open and laparoscopic abdominal surgeries, there are currently no safe and effective methods for intraoperative ureteral identification (IUI) and diagnosis (IUD). In this study, I designed and chemically synthesized a near-infrared fluorescence (NIRF) imaging probe (CD-NIR-1) and evaluated its clearance and ability for IUI and IUD in animal models. CD-NIR-1 demonstrated high specificity and ultrarapid clearance by rat kidneys to the urinary bladder following intravenous administration of a single dose (25 nmol/kg of body weight), with 96% of the dose ultimately excreted at the first urination with no chemical modification. Furthermore, urine containing CD-NIR-1 in ureters showed strong NIRF, thereby enabling IUI and IUD via NIRF imaging. These results demonstrated the efficacy of CD-NIR-1 for clinical use.

Highly Stable and Bright NIR-II AIE Dots for Intraoperative Identification of Ureter

Iatrogenic ureteral injury is a dreaded complication of abdominal and pelvic surgeries, and thus, intraoperative identification of ureters is of paramount importance but lacks efficient methods and probes. Herein, we used near-infrared II (NIR-II, 1000-1700 nm) fluorescence imaging with advantages of higher spatial resolution, deeper tissue penetration, lower light scattering, and less tissue autofluorescence to identify ureters by aggregation-induced emission luminogen dots (AIE dots). The intraoperative ureteral injuries and common ureteral diseases can be visualized timely and precisely. Due to the longer emission wavelength and higher quantum yield of the AIE dots, it largely outperforms the commercial indocyanine green dye in brightness and penetration depth. It was the first time to realize the intraoperative identification of ureters in vivo using NIR-II imaging. Thus, our work provides a new platform for intraoperative monitoring during clinical operation.

Key clinical applications for indocyanine green fluorescence imaging in minimally invasive colorectal surgery

Near-infrared indocyanine green (ICG) fluorescence imaging has gained solid acceptance over the last years, and rightly so, as this technology has so much to offer, especially in the field of minimally invasive surgery. Firm evidence from ongoing and future studies will hopefully transform many of the applications of ICG fluorescence into the standard of care for our patients. This review examines the current status of ICG fluorescence for assessment of bowel perfusion, lymphatic mapping as well as intraoperative localisation of ureter in light of the published academic literature in English.

Iatrogenic ureteral injuries and their prevention in colorectal surgery: results from a nationwide survey

AIM

Iatrogenic ureteral injury (IUI) occurs rarely during colorectal surgery but is associated with significant mortality, morbidity and medicolegal issues. Few cases are reported, and recommendations regarding prevention are lacking. The aim of this study is to describe the current state of practice regarding IUI and its prevention among general surgeons in Switzerland.

METHOD

All Swiss general surgeons who are members of either the Swiss Association of Laparoscopic and Thoracoscopic Surgery or the Swiss Surgical Society were invited to participate in an anonymous online survey. Demographics, surgical practice, rate of IUI and methods used to prevent IUI were investigated.

RESULTS

All participants were board-certified general surgeons, 63.4% were certified visceral surgeons and 17.9% were certified colorectal surgeons. The mean level of experience in colorectal surgery was 15.6 ± 9.2 years. Formal ureter identification was considered mandatory during sigmoid or rectal surgery by 83.7% of participants, and 31.7% considered identification of the right ureter during right colectomy to be mandatory. In total, 61.8% of the participants and 78.4% of surgeons with more than 20 years of experience had encountered at least one IUI. Prophylactic ureteral stenting was considered useful in complex procedures by 93.5% of participants, and 56.9% had used stents at least once in the past 12 months. Noninvasive techniques for identifying ureters would be considered in regular daily practice by 54.5% of the participants.

CONCLUSION

Most general surgeons experience IUI. Ureter identification is widely integrated in colorectal procedures. Prophylactic stenting is widely used for difficult cases. Noninvasive methods to improve ureter identification are now needed.

Currently available and experimental dyes for intraoperative near-infrared fluorescence imaging of the ureters: a systematic review

Background

Iatrogenic ureteral injury (IUI) following abdominal surgery has a relatively low incidence, but is associated with high risks of morbidity and mortality. Conventional assessment of IUI includes visual inspection and palpation. This is especially challenging during laparoscopic procedures and has translated into an increased risk of IUI. The use of near-infrared fluorescent (NIRF) imaging is currently being considered as a novel method to identify the ureters intraoperatively. The aim of this review is to describe the currently available and experimental dyes for ureter visualization and to evaluate their feasibility of using them and their effectiveness.

Methods

This article adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standard for systematic reviews. A systematic literature search was performed in the PubMed database. All included articles were screened for eligibility by two authors. Three clinical trial databases were consulted to identify ongoing or completed unpublished trials. Risk of bias was assessed for all articles.

Results

The search yielded 20 articles on ureter visualization. Two clinically available dyes, indocyanine green (ICG) and methylene blue (MB), and eight experimental dyes were described and assessed for their feasibility to identify the ureter. Two ongoing clinical trials on CW800-BK and one trial on ZW800-1 for ureter visualization were identified.

Conclusions

Currently available dyes, ICG and MB, are safe, but suboptimal for ureter visualization based on the route of administration and optical properties, respectively. Currently, MB has potential to be routinely used for ureter visualization in most patients, but (cRGD-)ZW800-1 holds potential for this role in the future, owing to its exclusive renal clearance and the near absence of background. To assess the benefit of NIRF imaging for reducing the incidence of IUI, larger patient cohorts need to be examined.

Electronic supplementary material

The online version of this article (10.1007/s10151-019-01973-4) contains supplementary material, which is available to authorized users.

Near-infrared fluorescence laparoscopy of the ureter with three preclinical dyes in a pig model

Background

Ureteric injury is reported to occur in 1–7.6% of colorectal surgeries. To reduce the incidence of ureteral injury, it is essential to identify the ureters. The use of near-infrared fluorescence (NIRF) imaging with intravenously administered dyes might be of added value for ureteral visualization during laparoscopy. The aim of this study is to assess the performance of three preclinical dyes; IRDye^® 800BK, IRDye^® 800NOS and IRDye^® 800CW, for near-infrared fluorescence laparoscopy of the ureter in pigs.

Methods

In three female Dutch landrace pigs, the new dyes were evaluated. In each pig, 1 dye was tested using a 6-mg intravenous dose in a concentration of 1 mg/ml. Imaging was performed in fluorescence mode and white light mode with a laparoscopic imaging system. In order to further evaluate the dyes, an ex vivo imaging experiment was performed, in which 8 decreasing concentrations per dye, diluted in PBS, were evaluated in a transparent test tube with NIRF mode at a distance of 1, 5 and 10 cm from the laparoscope.

Results

All three dyes were effective in allowing the identification of the ureter with NIRF imaging. The ureter became fluorescent after 35, 45 and 10 min, respectively, for IRDye^® 800BK, IRDye^® 800NOS and IRDye^® 800CW with a maximum target-to-background ratio (TBR) of 2.14, 0.66 and 1.44, respectively. In the ex vivo imaging experiment, all three dyes produced a strong fluorescence signal at all concentrations and all distances evaluated.

Conclusions

Intravenous administration of the preclinical dyes IRDye^® 800CW, IRDye^® 800 BK and IRDye^® 800NOS facilitated successful identification of the anatomical course of the ureter in living pig models. The highest measured TBR occurred with the use of IRDye^® 800BK. Ex vivo, a correlation was observed between the fluorescence intensities of the signal with the concentration of the dye and with the distance to the object.