Robot-assisted fluorescent sentinel lymph node identification in early-stage colon cancer.

BACKGROUND: Patients with cT1-2 colon cancer (CC) have a 10-20% risk of lymph node metastases. Sentinel lymph node identification (SLNi) could improve staging and reduce morbidity in future organ-preserving CC surgery. This pilot study aimed to assess safety and feasibility of robot-assisted fluorescence-guided SLNi using submucosally injected indocyanine green (ICG) in patients with cT1-2N0M0 CC. METHODS: Ten consecutive patients with cT1-2N0M0 CC were included in this prospective feasibility study. Intraoperative submucosal, peritumoral injection of ICG was performed during a colonoscopy. Subsequently, the near-infrared fluorescence 'Firefly' mode of the da Vinci Xi robotic surgical system was used for SLNi. SLNs were marked with a suture, after which a segmental colectomy was performed. The SLN was postoperatively ultrastaged using serial slicing and immunohistochemistry, in addition to the standard pathological examination of the specimen. Colonoscopy time, detection time (time from ICG injection to first SLNi), and total SLNi time were measured (time from the start of colonoscopy to start of segmental resection). Intraoperative, postoperative, and pathological outcomes were registered. RESULTS: In all patients, at least one SLN was identified (mean 2.3 SLNs, SLN diameter range 1-13 mm). No tracer-related adverse events were noted. Median colonoscopy time was 12 min, detection time was 6 min, and total SLNi time was 30.5 min. Two patients had lymph node metastases present in the SLN, and there were no patients with false negative SLNs. No patient was upstaged due to ultrastaging of the SLN after an initial negative standard pathological examination. Half of the patients unexpectedly had pT3 tumours. CONCLUSIONS: Robot-assisted fluorescence-guided SLNi using submucosally injected ICG in ten patients with cT1-2N0M0 CC was safe and feasible. SLNi was performed in an acceptable timespan and SLNs down to 1 mm were detected. All lymph node metastases would have been detected if SLN biopsy had been performed.

Detection of Tumour-Targeted IRDye800CW Tracer with Commercially Available Laparoscopic Surgical Systems.

(1) Introduction: Near-infrared fluorescence (NIRF) combined with tumour-targeted tracers, such as bevacizumab-800CW, could aid surgical decision-making. This study explored the use of IRDye800CW, conjugated to bevacizumab, with four commercially available NIRF laparoscopes optimised for indocyanine green (ICG). (2) Methods: A (lymph node) phantom was made from a calibration device for NIRF and tissue-mimicking material. Serial dilutions of bevacizumab-800CW were made and ICG functioned as a reference. System settings, working distance, and thickness of tissue-mimicking material were varied to assess visibility of the fluorescence signal and tissue penetration. Tests were performed with four laparoscopes: VISERA ELITE II, Olympus; IMAGE1 S™ 4U Rubina, KARL STORZ; ENDOCAM Logic 4K platform, Richard Wolf; da Vinci Xi, Intuitive Surgical. (3) Results: The lowest visible bevacizumab-800CW concentration ranged between 13-850 nM (8-512 times diluted stock solution) for all laparoscopes, but the tracer was not visible through 0.8 cm of tissue in all systems. In contrast, ICG was still visible at a concentration of 0.4 nM (16,384 times diluted) and through 1.6-2.4 cm of tissue. Visibility and tissue penetration generally improved with a reduced working distance and manually adjusted system settings. (4) Conclusion: Depending on the application, bevacizumab-800CW might be sufficiently visible with current laparoscopes, but optimisation would widen applicability of tumour-targeted IRDye800CW tracers.

Standardization and implementation of fluorescence molecular endoscopy in the clinic.

SIGNIFICANCE: Near-infrared fluorescence molecular endoscopy (NIR-FME) is an innovative technique allowing for in vivo visualization of molecular processes in hollow organs. Despite its potential for clinical translation, NIR-FME still faces challenges, for example, the lack of consensus in performing quality control and standardization of procedures and systems. This may hamper the clinical approval of the technology by authorities and its acceptance by endoscopists. Until now, several clinical trials using NIR-FME have been performed. However, most of these trials had different study designs, making comparison difficult. AIM: We describe the need for standardization in NIR-FME, provide a pathway for setting up a standardized clinical study, and describe future perspectives for NIR-FME. Body: Standardization is challenging due to many parameters. Invariable parameters refer to the hardware specifications. Variable parameters refer to movement or tissue optical properties. Phantoms can be of aid when defining the influence of these variables or when standardizing a procedure. CONCLUSION: There is a need for standardization in NIR-FME and hurdles still need to be overcome before a widespread clinical implementation of NIR-FME can be realized. When these hurdles are overcome, clinical outcomes can be compared and systems can be benchmarked, enabling clinical implementation.