Improved urethral fluorescence during low rectal surgery: a new dye and a new method

A novel Foley catheter made of high-intensity near-infrared fluorescent silicone rubber for image-guided surgery of lower rectal cancer

BACKGROUND

Urethral injury occurs in 1-6 % of male cases during minimally invasive surgery of lower rectal cancer. A Foley catheter emitting near-infrared (NIR) fluorescence of sufficient intensity has been expected to locate the urethra during image-guided surgery. Although it has been difficult to impart NIR fluorescent properties to biocompatible thermosetting polymers, we have recently succeeded in developing a NIR fluorescent compound for silicone rubber and a NIR fluorescent Foley catheter (HICARL). Here, we evaluated its NIR fluorescence properties and visibility performance using porcine anorectal isolation specimens.

METHODS

The HICARL catheter was made of a mixture of solid silicone rubber and a NIR fluorescent compound that emits fluorescence with a wavelength of 820-880 nm, while a conventional transparent Foley catheter was made of solid silicone rubber only. As a standard for comparison of the intensity of NIR fluorescence, a transparent Foley catheter the lumen of which was filled with a mixture of indocyanine green (ICG) and human plasma was used. As a comparison to assess the visibility performance of the HICARL catheter, a transparent Foley catheter into which a commercially available NIR fluorescent polyurethane ureteral catheter (NIRC) was placed was used.

RESULTS

A NIR fluorescence quantitative imaging analysis revealed that the Foley-NIRC catheter and the HICARL catheter emitted 3.42 ± 0.42 and 6.43 ± 0.07 times more fluorescence than the Foley-ICG catheter, respectively. The location of the HICARL catheter placed in the anorectum with a wall thickness of 3.8 ± 0.1 mm was clearly delineated in its entirety by NIR fluorescence, while that of the Foley-NIRC catheter was faintly or only partially visible.

CONCLUSIONS

The HICARL catheter emitting NIR fluorescence of sufficient intensity is a promising and easy-to-use tool for urethral visualization during image-guided surgery of lower rectal cancer.

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.

Preclinical Development and Validation of ASP5354: A Near-Infrared Fluorescent Agent for Intraoperative Ureter Visualization

PURPOSE

Iatrogenic ureteral injury (IUI) can complicate minimally invasive and open abdominopelvic surgery. The incidence of IUI is low and dependent on the type of surgery (< 10 %), but it is associated with high morbidity. Therefore, intraoperative visualization of the ureter is critical to reduce the incidence of IUI, and some methodologies for ureter visualization have been developed. Amongst these, near-infrared fluorescence (NIRF) visualization is thought to bring an advantage with real-time retroperitoneal visualization through the retroperitoneum. We investigated an indocyanine green (ICG) derivative, ASP5354, which emits NIRF at 820 nm when exposed to near-infrared light at a wavelength of 780 nm, in a rodent and porcine model.

PROCEDURES

Wistar rats and Göttingen minipigs under anesthesia were laparotomized and then administered ASP5354 chloride intravenously at dose of 0.03 and 0.3 mg/kg for rats and 0.001 and 0.01 mg/kg for minipigs, respectively. Videos of the abdominal cavity in minipigs were taken using a near-infrared fluorescent camera (pde-neo) and assessed visually by three independent clinicians. Toxicological evaluation was demonstrated with cynomolgus monkeys.

RESULTS

The proportion of animals whose ureters were visible up to 3 h after administration of ASP5354 chloride were 33 % at 0.001 mg/kg and 100 % at 0.01 mg/kg, respectively. In a toxicological study in cynomolgus monkeys, ASP5354 chloride demonstrated no significant toxicity, suggesting that 0.01 mg/kg provides an optimal dose when used clinically and could allow for ureter visualization during routine surgical procedures.

CONCLUSIONS

The dose of 0.01 mg/kg provided an optimal dose for ureter visualization up to 3 h after administration. ASP5354 shows promise for ureter visualization during abdominopelvic surgery, which may potentially lower the risk of IUI.

Indocyanine Green Fluorescence Guided Surgery in Colorectal Surgery

BACKGROUND

Indocyanine green (ICG) imaging has been increasingly used for intraoperative guidance in colorectal surgery over the past decade. The aim of this study was to review and organize, according to different type of use, all available literature on ICG guided colorectal surgery and highlight areas in need of further research and discuss future perspectives.

METHODS

PubMed, Scopus, and Google Scholar databases were searched systematically through November 2022 for all available studies on fluorescence-guided surgery in colorectal surgery.

RESULTS

Available studies described ICG use in colorectal surgery for perfusion assessment, ureteral and urethral assessment, lymphatic mapping, and hepatic and peritoneal metastases assessment. Although the level of evidence is low, results are promising, especially in the role of ICG in reducing anastomotic leaks.

CONCLUSIONS

ICG imaging is a safe and relatively cheap imaging modality in colorectal surgery, especially for perfusion assessment. Work is underway regarding its use in lymphatic mapping, ureter identification, and the assessment of intraperitoneal metastatic disease.

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.

Intraoperative use of indocyanine green fluorescence imaging in rectal cancer surgery: The state of the art

Indocyanine green (ICG) fluorescence imaging is widely used in abdominal surgery. The implementation of minimally invasive rectal surgery using new methods like robotics or a transanal approach required improvement of optical systems. In that setting, ICG fluorescence optimizes intraoperative vision of anatomical structures by improving blood and lymphatic flow. The purpose of this review was to summarize all potential applications of this upcoming technology in rectal cancer surgery. Each type of use has been separately addressed and the evidence was investigated. During rectal resection, ICG fluorescence angiography is mainly used to evaluate the perfusion of the colonic stump in order to reduce the risk of anastomotic leaks. In addition, ICG fluorescence imaging allows easy visualization of organs such as the ureter or urethra to protect them from injury. This intraoperative technology is a valuable tool for conducting lymph node dissection along the iliac lymphatic chain or to better identifying the rectal dissection planes when a transanal approach is performed. This is an overview of the applications of ICG fluorescence imaging in current surgical practice and a synthesis of the results obtained from the literature. Although further studies are need to investigate the real clinical benefits, these findings may enhance use of ICG fluorescence in current clinical practice and stimulate future research on new applications.

A novel method for near-infrared fluorescence imaging of the urethra during perineal and transanal surgery: demonstration in a cadaveric model

AIM

Transanal total mesorectal excision is a promising novel sphincter-saving procedure for low rectal cancer. However, the transanal bottom-up dissection is associated with increased rates of iatrogenic urethral injuries. Near-infrared fluorescence (NIRF) imaging, given its deeper tissue penetration, has been explored in a limited number of studies for enhanced intra-operative urethral visualization. In this study, we explored the feasibility of a novel, ultrabright, biocompatible fluorescent polymer to coat urinary catheters for the purpose of intra-operative urethral visualization.

METHODS

In an ex vivo experiment, using a near-infrared laparoscope, the fluorescent signal of a coated catheter (near-infrared coating of equipment, NICE) was qualitatively and quantitatively compared to the signal of indocyanine green (ICG)/Instillagel® mixtures and ICG-filled catheters at several concentrations. Also, in three male human torsos, using fluorescent urinary catheters, NIRF-guided perineal dissections and a transanal total mesorectal excision were performed. Intra-operative NIRF-based urethral visualization was performed systematically.

RESULTS

During the qualitative and quantitative fluorescence signal assessment, NICE-coated catheters were clearly superior to the ICG-based solutions. In the cadaveric experiments, enhanced urethral visualization was possible even at early stages of dissection, when the organ was covered by several tissue layers.

CONCLUSIONS

NICE-coated catheters represent a promising potential to allow for NIRF-based intra-operative urethral visualization.

Near infrared fluorescence imaging of the urethra: a systematic review of the literature

BACKGROUND

Urethral injury is a dreaded complication during laparoscopic, perineal and transanal surgery and is mainly a result of a failed visualization of the urethra. The aim of this systematic review is to provide an overview of the available literature on the near-infrared fluorescence (NIRF) imaging technique using contrast agents for the intra-operative visualization of the urethra.

MATERIAL AND METHODS

A systematic review of the literature was conducted including studies on NIRF imaging using contrast agents to visualize the urethra. All studies describing a NIRF imaging technique and demonstrating visual findings of the urethra were included.

RESULTS

Five studies were identified. Four studies examined indocyanine green, one of which also studied the IRDye^® 800BK agent and one examined the CP-IRT dye. All studies showed that the NIRF imaging technique was feasible for an early identification of the urethra. No complications related to NIRF imaging were reported.

CONCLUSION

We conclude that the use of a NIRF imaging technique is feasible and that it can contribute to prevent iatrogenic injury to the urethra. However, based on the limited available data, no solid conclusion can yet be drawn and further translation to the clinical practice is necessary.

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.

Future Directions

Transanal total mesorectal excision (taTME) is a novel technique that has evolved over the years to address the challenges of low rectal cancer surgery by applying the principles and benefits of laparoscopic surgery to more historic transanal techniques. It has been popularized through its use in rectal cancer, but the transanal approach is slowly being expanded to tackle different clinical scenarios including benign conditions such as inflammatory bowel disease and endometriosis. For all of these new indications, it is the desire to access and begin the dissection in native tissue beyond the pathology which makes this approach applicable to other diseases where anatomy can be challenging. Training pathways to safely introduce taTME in a standardized manner are being developed and implemented in a bid to ensure adequate training to all the surgeons using this technique and thus minimize complications and patient morbidity. The future directions of this promising technique include the use of image and optical technological enhancement to aid navigation, the use of pneumorectum stabilization, and perhaps the use of fluorescence as a safety improvement. Developments have come also from the field of robotics. After a demonstration of feasibility in cadaver models, a growing experience has been gathered in the robotic approach to taTME, covered in the last part of this chapter.

Urethral Injury and Other Urologic Injuries During Transanal Total Mesorectal Excision: An International Collaborative Study

OBJECTIVE

To identify risk factors for urethral and urologic injuries during transanal total mesorectal excision (taTME) and evaluate outcomes.

BACKGROUND

Urethral injury is a rare complication of abdominoperineal resection (APR) that has not been reported during abdominal proctectomy. The Low Rectal Cancer Development Program international taTME registry recently reported a 0.8% incidence, but actual incidence and mechanisms of injury remain largely unknown.

METHODS

A retrospective analysis of taTME cases complicated by urologic injury was conducted. Patient demographics, tumor characteristics, intraoperative details, and outcomes were analyzed, along with surgeons' experience and training in taTME. Surgeons' opinion of contributing factors and best approaches to avoid injuries were evaluated.

RESULTS

Thirty-four urethral, 2 ureteral, and 3 bladder injuries were reported during taTME operations performed over 7 years by 32 surgical teams. Twenty injuries occurred during the teams' first 8 taTME cases ("early experience"), whereas the remainder occurred between the 12th to 101st case. Injuries resulted in a 22% conversion rate and 8% rate of unplanned APR or Hartmann procedure. At median follow-up of 27.6 months (range, 3-85), the urethral repair complication rate was 26% with a 9% rate of failed urethral repair requiring permanent urinary diversion. In patients with successful repair, 18% reported persistent urinary dysfunction.

CONCLUSIONS

Urologic injuries result in substantial morbidity. Our survey indicated that those occurring in surgeons' early experience might best be reduced by implementation of structured taTME training and proctoring, whereas those occurring later relate to case complexity and may be avoided by more stringent case selection.

Robotic-assisted stereotactic real-time navigation: initial clinical experience and feasibility for rectal cancer surgery

BACKGROUND

Real-time stereotactic navigation for transanal total mesorectal excision has been demonstrated to be feasible in small pilot series using laparoscopic techniques. The possibility of real-time stereotactic navigation coupled with robotics has not been previously explored in a clinical setting.

METHODS

After pre-clinical assessment, and configuration of a robotic-assisted navigational system, two patients with locally advanced rectal cancer were selected for enrollment into a pilot study designed to assess the feasibility of navigation coupled with the robotic da Vinci Xi platform via TilePro interface. In one case, fluorescence-guided surgery was also used as an adjunct for structure localization, with local administration of indocyanine green into the ureters and at the tumor site.

RESULTS

Each operation was successfully completed with a robotic-assisted approach; image-guided navigation provided computed accuracy of ± 4.5 to 4.6 mm. The principle limitation encountered was navigation signal dropout due to temporary loss of direct line-of-sight with the navigational system's infrared camera. Subjectively, the aid of navigation assisted the operating surgeon in identifying critical anatomical planes. The combination of fluorescence with image-guided surgery further augmented the surgeon's perception of the operative field.

CONCLUSIONS

The combination of stereotactic navigation and robotic surgery is feasible, although some limitations and technical challenges were observed. For complex surgery, the addition of navigation to robotics can improve surgical precision. This will likely represent the next step in the evolution of robotics and in the development of digital surgery.