A pilot study to assess near infrared laparoscopy with indocyanine green (ICG) for intraoperative sentinel lymph node mapping in early colon cancer

Fluorescence and tracers in surgery: the coming future

The revolution that we are seeing in the world of surgery will determine the way we understand surgical approaches in coming years. Since the implementation of minimally invasive surgery, innovations have constantly been developed to allow the laparoscopic approach to go further and be applied to more and more procedures. In recent years, we have been in the middle of another revolutionary era, with robotic surgery, the application of artificial intelligence and image-guided surgery. The latter includes 3D reconstructions for surgical planning, virtual reality, holograms or tracer-guided surgery, where ICG-guided fluorescence has provided a different perspective on surgery. ICG has been used to identify anatomical structures, assess tissue perfusion, and identify tumors or tumor lymphatic drainage. But the most important thing is that this technology has come hand in hand with the potential to develop other types of tracers that will facilitate the identification of tumor cells and ureters, as well as different light beams to identify anatomical structures. These will lead to other types of systems to assess tissue perfusion without the use of tracers, such as hyperspectral imaging. Combined with the upcoming introduction of ICG quantification, these developments represent a real revolution in the surgical world. With the imminent implementation of these technological advances, a review of their clinical application in general surgery is timely, and this review serves that aim.

Indocyanine Green Tattooing During Colonoscopy as a Guide to Laparoscopic Colorectal Cancer Surgery: A Literature Review

BACKGROUND

Endoscopic tattooing of colorectal lesions has been performed employing several markers. The indocyanine green (ICG) that uses near infrared fluorescence technology, has been recently adopted in laparoscopic colorectal cancer surgery. This study aims to systematically review the international literature to validate the ICG in laparoscopic colorectal surgery, in order to include the ICG in the therapeutic protocol.

METHODS

Following AMSTAR 2 criteria, we performed a systematic review to evaluate the use of green indocyanine as a marker for preoperative endoscopic tattooing and for lymph nodes mapping. The study selection was conducted using the PubMed database from January 1989 to July 2022.

RESULTS

We identified 25 eligible studies. 13 based on fluorescent tumor localization in laparoscopic colorectal surgery using ICG while 12 of them reported the lymphatic road mapping and sentinel node identification by ICG using a near-infrared camera system. One study analyzed both topics.

CONCLUSIONS

In laparoscopic colorectal cancer surgery indocyanine green can be used to localize fluorescent tumors and mapping fluorescence lymph node. The use of ICG appears to be a valid and safe technique that helps the surgeon to achieve a better oncological radicality. However, the protocols need to be clarified by further studies.

Factors Affecting the Efficiency of Near-Infrared Indocyanine Green (NIR/ICG) in Lymphatic Mapping for Colorectal Cancer: A Systematic Review

As laparoscopy gained global popularity in oncologic surgery, the challenge of detecting lymph nodes spurred researchers to explore innovative techniques and approach the situation from a fresh perspective. While many proposed methods have faded into obscurity, the utilization of indocyanine green (ICG) in the surgical treatment of oncologic patients has continued to advance. The immense potential of this dye is widely acknowledged, yet its full extent and limitations in lymphatic mapping for colorectal cancer remain to be precisely determined. This article aims to assess the magnitude of its potential and explore the constraints based on insights from clinical studies published by pioneering researchers. A systematic review of the existing literature, comprising articles in English, was conducted using the Scopus, PubMed, and Springer Link databases. The search employed keywords such as "colorectal cancer" AND/OR "indocyanine green," "fluorescence" AND/OR "lymphatic mapping" AND/OR "lymph nodes." Initially identifying 129 articles, the application of selection criteria narrowed down the pool to 10 articles, which served as the primary sources of data for our review. Despite the absence of a standardized protocol for the application of ICG in colorectal cancer, particularly in the context of lymphatic mapping, the detection rates have exhibited considerable variation across studies. Nevertheless, all authors unanimously regarded this technique as beneficial and promising. Additionally, it is advocated as an adjunctive tool to enhance the accuracy of cancer staging. Near-infrared (NIR)-enhanced surgery holds the promise of transforming the landscape of oncologic surgery, emerging as a valuable tool for surgeons. However, the absence of a standardized technique and the subjective nature of result assessment impose limitations on the potential of this method. Consequently, it can be inferred that the establishment of a universally accepted protocol, encompassing parameters such as dose, concentration, technique, and site of administration of ICG, along with the optimal time needed for fluorescence visualization, would enhance the outcomes. Emphasizing the accurate selection of patients is crucial to prevent the occurrence of false-negative results.

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.

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

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

Application of near-infrared fluorescence imaging in theranostics of gastrointestinal tumors

Gastrointestinal cancers have become an important cause of cancer-related death in humans. Improving the early diagnosis rate of gastrointestinal tumors and improving the effect of surgical treatment can significantly improve the survival rate of patients. The conventional diagnostic method is high-definition white-light endoscopy, which often leads to missed diagnosis. For surgical treatment, intraoperative tumor localization and post-operative anastomotic state evaluation play important roles in the effect of surgical treatment. As a new imaging method, near-infrared fluorescence imaging (NIRFI) has its unique advantages in the diagnosis and auxiliary surgical treatment of gastrointestinal tumors due to its high sensitivity and the ability to image deep tissues. In this review, we focus on the latest advances of NIRFI technology applied in early diagnosis of gastrointestinal tumors, identification of tumor margins, identification of lymph nodes, and assessment of anastomotic leakage. In addition, we summarize the advances of NIRFI systems such as macro imaging and micro imaging systems, and also clearly describe the application process of NIRFI from system to clinical application, and look into the prospect of NIRFI applied in the theranostics of gastrointestinal tumors.

miRNAs orchestration of gallbladder cancer - Particular emphasis on diagnosis, progression and drug resistance

Gallbladder cancer (GBC) is characterized by a highly invasive nature and a poor prognosis, with adenocarcinoma being the main histological subtype. According to statistical data, patients diagnosed with advanced GBC have a survival rate of less than 5% for 5 years. Despite the novel therapeutic techniques, the unsatisfactory results could be related to the underlying biology of tumor cells and resistance to chemotherapy. Early diagnosis is more important than clinical therapy as it assists in determining the pathological stage of cancer and facilitates the selection of appropriate medication. Hence, it is very important to understand the precise pathogenesis of GBC and to discover potential novel biomarkers for early diagnosis of GBC. Non-coding RNAs, such as microRNAs, long non-coding RNAs, and circular RNAs, have been found to influence the transcriptional regulation of target genes associated with cancer, either directly or indirectly. microRNAs are a group of small, non-coding, single-stranded RNAs that are expressed endogenously. miRNAs play significant roles in various fundamental cellular processes. Therefore, miRNAs have the potential to serve as valuable biomarkers and therapeutic targets for GBC.

Lymphatic Mapping in Colon Cancer Depending on Injection Time and Tracing Agent: A Systematic Review and Meta-Analysis of Prospective Designed Studies

An optimized lymph node yield leads to better survival in colon cancer, but extended lymphadenectomy is not associated with survival benefits. Lymphatic mapping shows several colon cancers feature aberrant drainage pathways inducing local recurrence when not resected. Currently, different protocols exist for lymphatic mapping procedures. This meta-analysis assessed which protocol has the best capacity to detect tumor-draining and possibly metastatic lymph nodes. A systematic review was conducted according to PRISMA guidelines, including prospective trials with in vivo tracer application. The risk of bias was evaluated using the QUADAS-2 tool. Traced lymph nodes, total resected lymph nodes, and aberrant drainage detection rate were analyzed. Fifty-eight studies met the inclusion criteria, of which 42 searched for aberrant drainage. While a preoperative tracer injection significantly increased the traced lymph node rates compared to intraoperative tracing (30.1% (15.4, 47.3) vs. 14.1% (11.9, 16.5), p = 0.03), no effect was shown for the tracer used (p = 0.740) or the application sites comparing submucosal and subserosal injection (22.9% (14.1, 33.1) vs. 14.3% (12.1, 16.8), p = 0.07). Preoperative tracer injection resulted in a significantly higher rate of detected aberrant lymph nodes compared to intraoperative injection (26.3% [95% CI 11.5, 44.0] vs. 2.5% [95% CI 0.8, 4.7], p < 0.001). Analyzing 112 individual patient datasets from eight studies revealed a significant impact on aberrant drainage detection for injection timing, favoring preoperative over intraoperative injection (OR 0.050 [95% CI 0.010-0.176], p < 0.001) while indocyanine green presented itself as the superior tracer (OR 0.127 [95% CI 0.018-0.528], p = 0.012). Optimized lymphatic mapping techniques result in significantly higher detection of aberrant lymphatic drainage patterns and thus enable a personalized approach to reducing local recurrence.

European Association for Endoscopic Surgery (EAES) consensus on Indocyanine Green (ICG) fluorescence-guided surgery

BACKGROUND

In recent years, the use of Indocyanine Green (ICG) fluorescence-guided surgery during open and laparoscopic procedures has exponentially expanded across various clinical settings. The European Association of Endoscopic Surgery (EAES) initiated a consensus development conference on this topic with the aim of creating evidence-based statements and recommendations for the surgical community.

METHODS

An expert panel of surgeons has been selected and invited to participate to this project. Systematic reviews of the PubMed, Embase and Cochrane libraries were performed to identify evidence on potential benefits of ICG fluorescence-guided surgery on clinical practice and patient outcomes. Statements and recommendations were prepared and unanimously agreed by the panel; they were then submitted to all EAES members through a two-rounds online survey and results presented at the EAES annual congress, Barcelona, November 2021.

RESULTS

A total of 18,273 abstracts were screened with 117 articles included. 22 statements and 16 recommendations were generated and approved. In some areas, such as the use of ICG fluorescence-guided surgery during laparoscopic cholecystectomy, the perfusion assessment in colorectal surgery and the search for the sentinel lymph nodes in gynaecological malignancies, the large number of evidences in literature has allowed us to strongly recommend the use of ICG for a better anatomical definition and a reduction in post-operative complications.

CONCLUSIONS

Overall, from the systematic literature review performed by the experts panel and the survey extended to all EAES members, ICG fluorescence-guided surgery could be considered a safe and effective technology. Future robust clinical research is required to specifically validate multiple organ-specific applications and the potential benefits of this technique on clinical outcomes.

Opportunities of ICG-fluorescent imaging of lymph nodes during radical cystectomy in patients with bladder cancer: A review

Today, the "golden standard" for the treatment of aggressive forms of bladder cancer is radical cystectomy. An important stage is the pelvic lymphadenectomy. This procedure is crucial for staging the tumor process, determining the subsequent treatment tactics and improving the results of surgery. Currently, the concept of a signaling lymph node (LN) is actively developing, which allows reducing the necessary level of dissection of the pelvic LN. Reducing the number of resected LN increases the level of surgical safety of the patient. The leading method of intraoperative visualization of signal LN is the fluorescence of indocyanine green in the near infrared range of the spectrum. The prospects of this diagnostic method for radical cystectomy in patients with bladder cancer determine the vector of future scientific research in this area.

Timing of real-time indocyanine green fluorescence visualization for lymph node dissection during laparoscopic colon cancer surgery

PURPOSE

Although numerous studies have highlighted the potential value of indocyanine green (ICG) imaging in lymph node dissection of cancer surgery, its efficacy and optimal method remain to be clarified. This study aimed to investigate how lymphatic flow observation via ICG fluorescence could contribute to colon cancer surgery.

METHODS

From October 2018 to March 2021, a total of 56 patients with colon cancer who underwent laparoscopic complete mesocolic excision with intraoperative ICG imaging were analyzed. Lymphatic flow was examined at the following time points following ICG injection: within 5 min, 30-60 min, and over 60 min. We also evaluated the distribution of ICG fluorescence per each vascular pedicle.

RESULTS

Lymphatic flow was observed within 5 min following ICG injection in 6 cases (10.7%), and at 30-60 min following ICG injection in 43 cases (76.8%). ICG-stained vascular pedicles were variable especially in hepatic flexural, transverse, and splenic flexural colon cancer. Lymph node metastases were observed in 14 cases. Although metastatic lymph nodes were present only in the area along the ICG-stained vascular pedicles in 12 of the 14 cases, two patients exhibited lymph node metastasis in areas along the ICG-unstained vascular pedicles. ICG fluorescence was observed outside the standard range of lymph node dissection in 9 cases (20.9%: 9/43). Although addition of the proposed resection areas was made in 8 of these 9 cases, there was no pathologically positive lymph node.

CONCLUSION

Real-time ICG fluorescence imaging of lymph nodes may improve the performance of laparoscopic colon cancer surgery, although its oncological benefit is not yet clear.

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.

Indocyanine Green Fluorescence-Guided Surgery for Gastrointestinal Tumors: A Systematic Review

Objective

To conduct a systematic review of the currently available literature on the use of ICG to guide surgical dissection in gastrointestinal (GI) cancer surgery.

Background

Real-time indocyanine green (ICG) fluorescence-guided surgery has the potential to enhance surgical outcomes by increasing patient-tailored oncological precision.

Methods

MEDLINE, PubMed, EMBASE, and Google Scholar were searched for publications on the use of ICG as a contrast agent in GI cancer surgery until December 2020. Perfusion studies were excluded. Quality of the studies was assessed with the Methodological Index for nonrandomized Studies or Jadad scale for randomized controlled trials. A narrative synthesis of the results was provided, with descriptive statistics when appropriate.

Results

Seventy-eight studies were included. ICG was used for primary tumor and metastases localization, for sentinel lymph node detection, and for lymph flow mapping. The detection rate for primary colorectal and gastric tumors was 100% after preoperative ICG endoscopic injection. For liver lesions, the detection rate after intravenous ICG infusion was 80% and up to 100% for lesions less than 8 mm from the liver surface. The detection rate for sentinel lymph nodes was 89.8% for esophageal, 98.6% for gastric, 87.4% for colorectal, and 83.3% for anal tumors, respectively. In comparative studies, ICG significantly increases the quality of D2 lymphadenectomy in oncological gastrectomy.

Conclusion

The use of ICG as a guiding tool for dissection in GI surgery is promising. Further evidence from high-quality studies on larger sample sizes is needed to assess whether ICG-guided surgery may become standard of care.

Indocyanine green (ICG) fluorescence guide for the use and indications in general surgery: recommendations based on the descriptive review of the literature and the analysis of experience

Indocyanine Green is a fluorescent substance visible in near-infrared light. It is useful for the identification of anatomical structures (biliary tract, ureters, parathyroid, thoracic duct), the tissues vascularization (anastomosis in colorectal, esophageal, gastric, bariatric surgery, for plasties and flaps in abdominal wall surgery, liver resection, in strangulated hernias and in intestinal ischemia), for tumor identification (liver, pancreas, adrenal glands, implants of peritoneal carcinomatosis, retroperitoneal tumors and lymphomas) and sentinel node identification and lymphatic mapping in malignant tumors (stomach, breast, colon, rectum, esophagus and skin cancer). The evidence is very encouraging, although standardization of its use and randomized studies with higher number of patients are required to obtain definitive conclusions on its use in general surgery. The aim of this literature review is to provide a guide for the use of ICG fluorescence in general surgery procedures.

Lymph Node Mapping for Tumor Micrometastasis

Lymph node mapping for tumor micrometastasis is of great significance for the prevention, prognosis, and treatment of cancer. Currently, the traditional clinical detection methods (computed tomography, magnetic resonance imaging, or positron emission tomography/computed tomography) in clinical lymph node mapping still have some inherent disadvantages, which have prompted the development of various fluorescent probes for lymph node mapping. However, the conventional fluorescent probes such as indocyanine green or methylene blue in lymph node mapping are still accompanied by several problems such as impaired surgical field vision due to dye staining or less accumulation and shorter retention time in the lymph node. In a recent achievement, newly designed nanoparticles are prepared with novel properties that could be attractive for lymph node mapping. In this review, we will provide details on the progress of various nanoparticles for lymph node mapping and emphasize other multivariant properties in different nanoparticles, including strong tumor-targeting affinity and specificity, self-luminescence, and even with the function to kill metastatic cancer cells.

Combined laparoscopic lymphoadenectomy of lateral pelvic and inguinal nodal metastases using indocyanine green fluorescence imaging guidance in low rectal cancer after preoperative chemoradiotherapy: a case report

Background

Intraoperative near-infrared fluorescence (NIR) imaging with indocyanine green (ICG) can demonstrate real-time lymphatic drainage and thus improve the accuracy and completeness of lymphadenectomy in colorectal cancer surgery. However, it has not been utilized in the inguinal lymphadenectomy in rectal cancer. This study aimed to describe a case of combined laparoscopic lymphadenectomy of left lateral pelvic and inguinal nodal metastases using NIR imaging with ICG imaging guidance for a rectal cancer patient with left lateral pelvic and inguinal lymph node metastases.

Case presentation

A 26-year-old man presented rectal cancer located 7 cm from the anal verge and enlarged lymph nodes in the left inguinal area. Pretreatment workup revealed rectal cancer with left lateral pelvic and inguinal lymph node metastases. The patient received preoperative chemoradiotherapy (pCRT), including radiation (total dose of 50.4 Gy in 28 fractions) to the whole pelvis and bilateral inguinal regions together with eight cycles of FOLFOX (oxaliplatin, fluoropyrimidine, and leucovorin) and three cycles of bevacizumab targeted chemotherapy. After pCRT, both colonoscopy and MR scan revealed a significant response of the primary tumor to pCRT, while MR scan revealed enlarged left lateral pelvic and inguinal lymph nodes. After four months from the completion of radiation (2 months after the last course of bevacizumab targeted therapy), the patient underwent laparoscopic-assisted ultra-low anterior resection and lymphadenectomy of left lateral pelvic and inguinal nodal metastases using ICG-NIR fluorescence imaging. The combined procedure was performed successfully without perioperative complication. Total operative time was 480 min and estimated blood loss 50 mL. Totally 34 lymph nodes were retrieved.

Conclusions

This is the first report of the safety and feasibility of ICG-NIR fluorescence imaging-guided laparoscopic lymphadenectomy of left lateral pelvic and inguinal nodal metastases in managing low rectal cancer with lateral pelvic and inguinal LNs metastases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-022-02193-1.

Design Principles Governing the Development of Theranostic Anticancer Agents and Their Nanoformulations with Photoacoustic Properties

The unmet need to develop novel approaches for cancer diagnosis and treatment has led to the evolution of theranostic agents, which usually include, in addition to the anticancer drug, an imaging agent based mostly on fluorescent agents. Over the past few years, a non-invasive photoacoustic imaging modality has been effectively integrated into theranostic agents. Herein, we shed light on the design principles governing the development of theranostic agents with photoacoustic properties, which can be formulated into nanocarriers to enhance their potency. Specifically, we provide an extensive analysis of their individual constituents including the imaging dyes, drugs, linkers, targeting moieties, and their formulation into nanocarriers. Along these lines, we present numerous relevant paradigms. Finally, we discuss the clinical relevance of the specific strategy, as also the limitations and future perspectives, and through this review, we envisage paving the way for the development of theranostic agents endowed with photoacoustic properties as effective anticancer medicines.

Application of Magnetic Nanoparticles for Rapid Detection and In Situ Diagnosis in Clinical Oncology

Screening, monitoring, and diagnosis are critical in oncology treatment. However, there are limitations with the current clinical methods, notably the time, cost, and special facilities required for radioisotope-based methods. An alternative approach, which uses magnetic beads, offers faster analyses with safer materials over a wide range of oncological applications. Magnetic beads have been used to detect extracellular vesicles (EVs) in the serum of pancreatic cancer patients with statistically different EV levels in preoperative, postoperative, and negative control samples. By incorporating fluorescence, magnetic beads have been used to quantitatively measure prostate-specific antigen (PSA), a prostate cancer biomarker, which is sensitive enough even at levels found in healthy patients. Immunostaining has also been incorporated with magnetic beads and compared with conventional immunohistochemical methods to detect lesions; the results suggest that immunostained magnetic beads could be used for pathological diagnosis during surgery. Furthermore, magnetic nanoparticles, such as superparamagnetic iron oxide nanoparticles (SPIONs), can detect sentinel lymph nodes in breast cancer in a clinical setting, as well as those in gallbladder cancer in animal models, in a surgery-applicable timeframe. Ultimately, recent research into the applications of magnetic beads in oncology suggests that the screening, monitoring, and diagnosis of cancers could be improved and made more accessible through the adoption of this technology.

Sentinel lymph node detection by combining nonradioactive techniques with contrast agents: State of the art and prospects

The status of sentinel lymph nodes (SLNs) has a substantial prognostic value because these nodes are the first place where cancer cells accumulate along their spreading route. Routine SLN biopsy ("gold standard") involves peritumoral injections of radiopharmaceuticals, such as technetium-99m, which has obvious disadvantages. This review examines the methods used as "gold standard" analogs to diagnose SLNs. Nonradioactive preoperative and intraoperative methods of SLN detection are analyzed. Promising photonic tools for SLNs detection are reviewed, including NIR-I/NIR-II fluorescence imaging, photoswitching dyes for SLN detection, in vivo photoacoustic detection, imaging and biopsy of SLNs. Also are discussed methods of SLN detection by magnetic resonance imaging, ultrasonic imaging systems including as combined with photoacoustic imaging, and methods based on the magnetometer-aided detection of superparamagnetic nanoparticles. The advantages and disadvantages of nonradioactive SLN-detection methods are shown. The review concludes with prospects for the use of conservative diagnostic methods in combination with photonic tools.

Real-time fluorescence image-guided gastrointestinal oncologic surgery: Towards a new era

Technological improvements are crucial in the evolution of surgery. Real-time fluorescence-guided surgery (FGS) has spread worldwide, mainly because of its usefulness during the intraoperative decision-making processes. The success of any gastrointestinal oncologic resection is based on the anatomical identification of the primary tumor and its regional lymph nodes. FGS allows also to evaluate the blood perfusion at the gastrointestinal stumps after colorectal or esophageal resections. Therefore, a reduction on the anastomotic leak rates has been postulated as one of the foreseeable benefits provided by the use of FGS in these procedures. Although the use of fluorescence in lymph node detection was initially described in breast cancer surgery, the technique is currently applied in gastric or splenic flexure cancers, as they both present complex and variable lymphatic drainages. FGS allows also to perform intraoperative lymphograms or sentinel lymph node biopsies. New applications of FGS are being developed to assist in the detection of peritoneal metastases or in the evaluation of the tumor resection margins. The present review aims to provide a general overview of the current status of real-time FGS in gastrointestinal oncologic surgery. We put a special focus on the different applications of FGS, discussing the main findings and limitations found in the contemporary literature and also the promising near future applications.

Sentinel lymph node mapping for metastasis detection in colorectal cancer: a systematic review and meta-analysis

INTRODUCTION

controversy exists on the diagnostic performance of sentinel lymph node (SLN) mapping in colorectal cancer. This study aimed to provide a more precise estimation of its clinical significance.

MATERIALS AND METHODS

a systematic search of electronic databases was conducted to retrieve all relevant studies up to August 31st, 2019. Detection rate, sensitivity, and upstaging rate were pooled together, and a subgroup analysis was performed to identify factors that affect diagnostic performance. The prognostic value of upstaging was also explored.

RESULTS

sixty-eight studies were eligible and included. The pooled SLN detection rate was 0.93 (95 % CI, 0.91-0.94), with a significant higher rate in colon cancer or in studies including more than 100 patients. The overall sensitivity of the SLN procedure in colorectal cancer was 0.72 (95 % CI, 0.67-0.77). The tracers used were found to influence sensitivity. A mean weighted upstaging of 0.22 (95 % CI, 0.18-0.25) was identified. True upstaging, defined as micro-metastases, was 14 %. Upstaged patients were associated with worse overall survival (OS) when compared with node-negative patients (HR = 2.60, 95 % CI, 0.16-4.63). In addition, upstaged patients had a lower 5-year disease-free survival (DFS) rate than node-negative patients.

CONCLUSION

based on the results of the present meta-analysis, the SLN mapping procedure should focus on early stage patients to refine staging, since upstaging appeared to be a prognostic factor for DFS and OS. The SLN procedure can be recommended for colorectal cancer patients in addition to conventional resection.

Multifunctional Indocyanine Green Applications for Fluorescence-Guided Laparoscopic Colorectal Surgery

Indocyanine green (ICG) could be applied for multiple functions such as fluorescent tumor localization, fluorescence lymph node mapping (FLNM), and intraoperative angiography in colorectal cancer surgery. With the near-infrared (NIR) systems, colonoscopic ICG tattooing can be used to define the early colorectal cancer that cannot be easily distinguished through the serosal surface. The lymphatic pathways can be visualized under the NIR system when ICG is injected through the submucosal or subserosal layer around the tumor. Intraoperative ICG angiography can be applied to find a favorable perfusion segment before the colon transection. Although all fluorescence functions are considered essential steps in image-guided surgery, it is difficult to perform multifunctional ICG applications in a single surgical procedure at once because complex protocols could interfere with each other. Therefore, we review the multifunctional ICG applications for fluorescent tumor localization, FLNM, and ICG angiography. We also discuss the optimal protocol for fluorescence-guided colorectal surgery.

Could fluorescence-guided surgery be an efficient and sustainable option? A SICE (Italian Society of Endoscopic Surgery) health technology assessment summary

BACKGROUND

Indocyanine green fluorescence vision is an upcoming technology in surgery. It can be used in three ways: angiographic and biliary tree visualization and lymphatic spreading studies. The present paper shows the most outstanding results from an health technology assessment study design, conducted on fluorescence-guided compared with standard vision surgery.

METHODS

A health technology assessment approach was implemented to investigate the economic, social, ethical, and organizational implications related to the adoption of the innovative fluorescence-guided view, with a focus on minimally invasive approach. With the support of a multidisciplinary team, qualitative and quantitative data were collected, by means of literature evidence, validated questionnaires and self-reported interviews, considering the dimensions resulting from the EUnetHTA Core Model.

RESULTS

From a systematic search of literature, we retrieved the following studies: 6 on hepatic, 1 on pancreatic, 4 on biliary, 2 on bariatric, 4 on endocrine, 2 on thoracic, 11 on colorectal, 7 on urology, 11 on gynecology, 2 on gastric surgery. Fluorescence guide has shown advantages on the length of hospitalization particularly in colorectal surgery, with a reduction of the rate of leakages and re-do anastomoses, in spite of a slight increase in operating time, and is confirmed to be a safe, efficacious, and sustainable vision technology. Clinical applications are still presenting a low evidence in the literature.

CONCLUSION

The present paper, under the patronage of Italian Society of Endoscopic Surgery, based on an HTA approach, sustains the use of fluorescence-guided vision in minimally invasive surgery, in the fields of general, gynecologic, urologic, and thoracic surgery, as an efficient and economically sustainable technology.

Near-infrared laparoscopy with indocyanine green for axillary sentinel lymph node biopsy in early breast cancer: preliminary experience of a single unit

Background

A sentinel lymph node biopsy (SLNB) is a routine procedure for axillary staging in cN0 breast cancer (BC) patients. Indocyanine green (ICG) fluorescence can detect sentinel lymph nodes with higher sensitivity than carbon nanoparticle suspension (CNS). The present study investigated the availability and benefits of a near-infrared (NIR) laparoscopy-assisted SLNB using ICG and carbon nanoparticle suspension as tracers.

Methods

Forty patients with invasive BC, who had clinically negative axillary lymph nodes, participated in this observational study. ICG and CNS tracers were injected into the periareolar region simultaneously or sequentially. In the endoscopy-assisted group (n=20), the patients were given NIR laparoscopic SLNB based on ICG fluorescence and CNS staining. In the open-surgery group, the patients were given traditional SLNB using an open incision, and CNS tracers were injected into the same region as that in the endoscopy-assisted group.

Results

In the endoscopy-assisted group, lymphatic vessels and sentinel lymph nodes (SLNs) were successfully identified using ICG fluorescence imaging in most patients (19/20). The average number of SLNs removed was 2.85 (range, 1-4) in the endoscopy-assisted group, and 3.40 (range, 1-7) in the open-surgery group. There was no significant difference between the number of detected nodes (P=0.30). The patients who underwent endoscopy-assisted SLNBs had similar operating times, blood loss and hospital-stay lengths, but lower postoperative drainage volumes and higher satisfaction scores, as they did not have axillary incisions.

Conclusions

The NIR laparoscopy-assisted ICG-guided technique is a feasible and surgeon-friendly method for SLNB with good efficacy and acceptable safety. When combined with CNS, more SLNs can be detected and dissected.

Intraoperative laparoscopic detection of sentinel lymph nodes with indocyanine green and superparamagnetic iron oxide in a swine gallbladder cancer model

Mapping of sentinel lymph nodes (SLNs) can enable less invasive surgery. However, mapping is challenging for cancers of difficult-to-access visceral organs, such as the gallbladder, because the standard method using radioisotopes (RIs) requires preoperative tracer injection. Indocyanine green (ICG) and superparamagnetic iron oxide (SPIO) have also been used as alternative tracers. In this study, we modified a previously reported magnetic probe for laparoscopic use and evaluated the feasibility of detecting SLNs of the gallbladder using a laparoscopic dual tracer method by injecting ICG and SPIO into five swine and one cancer-bearing swine. The laparoscopic probe identified SPIO nanoparticles in the nodes of 4/5 swine in situ, the magnetic field counts were 2.5-15.9 μT, and fluorescence was detected in SLNs in all five swine. ICG showed a visual lymph flow map, and SPIO more accurately identified each SLN with a measurable magnetic field quite similar to the RI. We then developed an advanced gallbladder cancer model with lymph node metastasis using recombination activating gene 2-knockout swine. We identified an SLN in the laparoscopic investigation, and the magnetic field count was 3.5 μT. The SLN was histologically determined to be one of the two metastatic lymph nodes. In conclusion, detecting the SLNs of gallbladder cancer in situ using a dual tracer laparoscopic technique with ICG and SPIO was feasible in a swine model.

Fluorescence-guided D3 lymphadenectomy in robotic right colectomy with complete mesocolic excision

BACKGROUND

In robotic right hemicolectomy for cancer, appropriate lymphadenectomy is essential. Visualization of draining lymph nodes and blood flow with near-infrared (NIR) fluorescence DaVinci^® imaging system is a recent development. We present the technique of robotic right colectomy with complete mesocolic excision (CME) and D3 lymphadenectomy using Indocyanine Green (ICG) endoscopic submucosal injection to intraoperatively identify tumour lymphatic basin.

METHODS

The day before surgery, in patients scheduled for robotic right colectomy an endoscopic submucosal injection of 3 mg of ICG solution around the tumor is realized. Robotic right hemicolectomy is performed with suprapubic trocars layout and "bottom to up dissection", realizing a CME with central vessel ligation and D3 lymphadenectomy. Site of primary tumor and lymphatic basin are visible with the FireflyTM camera modality.

RESULTS

From July 2016 to July 2020, 85 patients received a robotic right colectomy with CME and D3 lymphadenectomy. In 50 patients, ICG submucosal injection was performed: visualisation of the site of primary tumour and of LN in the D3 area was possible in all cases; in 17/50 patients (34%), LN out from anatomical lymphatic basin were identified. No side effects were observed.

CONCLUSIONS

In this series, submucosal ICG injection showed to be feasible and safe. The accuracy in identification of D3 lymphatic basin was high, thus permitting an image-guided radical lymphadenectomy. Fluorescent technology represents an interesting innovation to ameliorate surgery of colon cancer.

Clinical application of carbon nanoparticles in lymphatic mapping during colorectal cancer surgeries: A systematic review and meta-analysis

OBJECTIVE

To investigate the overall performance of carbon nanoparticles (CNs) for detecting lymph nodes (LNs) and node metastasis during colorectal cancer surgery.

METHODS

The English and Chinese literature was searched until 29 April 2020. Studies were included if they were randomized controlled trials (RCTs) for colorectal resection and LN dissection that compared the use of CNs with a blank control in colorectal cancer surgery. Quality assessment and data extraction were performed, and a meta-analysis was conducted using ReviewManager 5.3 and Stata 15.1 software.

RESULTS

A total of 17 RCTs comprising 1241 patients were included for analysis. Compared with the outcomes of the blank controls, the use of CNs resulted in an average of 5.21 more LNs per patient (weighted mean difference = 5.21, 95% confidence interval [CI] = 4.14-6.29, p < 0.001) and a 68% higher detection rate of micro LNs (relative risk [RR] = 1.68, 95% CI = 1.38-2.04, p < 0.001). In addition, more metastatic LNs were identified in stained nodes (RR = 1.56, 95% CI = 1.40-1.75, p < 0.001), but the total detection rate of metastatic nodes did not differ between the groups.

CONCLUSION

CN is an effective lymphatic tracer in colorectal cancer surgeries. Further studies with larger sample sizes are needed to validate these findings.

In vivo sentinel lymph node identification using fluorescent tracer imaging in colon cancer: A systematic review and meta-analysis

INTRODUCTION

The use of fluorescence might improve the performance of the sentinel lymph node procedure in patients with colon cancer. This systematic review was conducted to gain insight in the performance and applicability of the sentinel lymph node procedure using fluorescence.

METHOD

A systematic literature search was performed. Databases were searched for prospective studies concerning sentinel node identification using fluorescence in colon cancer. Detection rate, accuracy rate and sensitivity of the sentinel lymph node procedure were calculated for early stage (T1-T2) and more invasive (T3-T4) tumours.

RESULTS

Analyses of five included studies showed for respectively T3-T4 and T1-T2 tumours a detection rate of 90 % and 91 %, an accuracy rate of 77 % and 98 %, and a sensitivity of 30 % and 80 %.

CONCLUSION

The sentinel lymph node procedure using fluorescence in early stage (T1-T2) colon cancer seems to be promising. Larger cohorts are necessary to confirm these results.

Colonic splenic flexure carcinoma: is laparoscopic segmental resection a safe enough oncological approach?

BACKGROUND

The surgical approach to the colonic splenic flexure cancer (SFC) is yet to be technically standardized. The aim of this study has been to retrospectively evaluate the oncologic long-term results of our cases comparing our data with other authors' experiences.

METHODS

Clinical data of patients with SFC operated on at our institute were retrospectively analyzed. The laparoscopic approach was used in the whole series, with limited resection distally and proximally to splenic flexure and the origin ligation of left colic artery and left branch of middle colic artery. Data on the oncological long-term safety were compared to our laparoscopic series of extended right colectomy for proximal two-third transverse colon cancer and high anterior resections for sigmoid-high rectal cancer and to the main evidences in the literature, found after a comprehensive review.

RESULTS

From March 2008 to May 2018, we completed 53 laparoscopic splenic flexure resections (26 female and 27 male, age 71.5 ± 15.4 years). The conversion rate was 3.8%. Most of the cases were stage II (pT3 73.5%, the mean number of lymph nodes harvested was 19.1, with positivity for malignancy in 45.3%). During the FU (43.5 months), 2 patients dropped out. Out of the 51 residual cases, 37 were alive (72.5%) and 14 are deceased (27.5%).

DISCUSSION

Compared to the literature, our survival rate does not show significant differences. The other oncological outcomes seem to be comparable with the data evaluated.

CONCLUSIONS

More extended resections seem not to confer an increase of the overall survival rate.

Standardized Step-by-step Technique Using Surgical Landmarks in Robotic Lateral Pelvic Lymph Node Dissection

We aimed to show that a standardized step-by-step robotic approach using surgical landmarks could make lateral pelvic lymph node dissection (LPND) less complicated. We performed robot-assisted LPND consisting of 4 steps using surgical landmarks. The first step is a dissection of uretero-hypogastric fascia, which envelopes the ureter and the hypogastric nerve. The second step is a dissection of the medial side of the external iliac vein located at the lateral border of the obturator lymph nodes (LNs) group. The third step is a dissection of the vesico-hypogastric fascia, which is at the medial border of the obturator LNs group. The final step is a dissection of the internal iliac artery until the Alcock’s canal. Indocyanine green was injected just before surgery around the dentate line to identify the lateral pelvic LNs. Standardization using a robotic approach for LPND guided by surgical landmarks allows a safer and more effective surgery.

Indocyanine Green-Enhanced Colorectal Surgery-between Being Superfluous and Being a Game-Changer

Nowadays, surgical innovations incorporate new technological conquests and must be validated by evidence-based medicine. The use of augmented reality-assisted indocyanine green (ICG) fluorescence has generated a myriad of intraoperative applications such as demonstration of key anatomical landmarks, sentinel lymph nodes, and real-time assessment of local blood flow. This paper presents a systematic review of the clinical evidence regarding the applications of ICG near-infrared (NIR) fluorescence in colorectal surgery. After we removed duplicate publications and screened for eligibility, a total of 36 articles were evaluated: 23 on perfusion assessment, 10 on lymph node mapping, and 3 on intraoperative identification of ureters. Lack of homogenous studies, low statistical power, and confounding evidence were found to be common amongst publications supporting the use of ICG in colorectal surgery, raising concerns over this seductive technique's cost efficiency and redundancy. The compiled data showed that ICG NIR fluorescence may be a game-changer in particular situations, as proven for low colorectal anastomosis or lateral pelvic lymph node dissection, but it remains controversial for routine use and sentinel lymph node assessment. Further randomized studies are needed to confirm these conclusions. Future research directions include tumor-targeted fluorescence imaging and digital software for quantitative evaluation of fluorescence.

Performance of Indocyanine green for sentinel lymph node mapping and lymph node metastasis in colorectal cancer: a diagnostic test accuracy meta-analysis

BACKGROUND

Indocyanine green has been widely employed as a secure and easy technique for sentinel lymph node mapping in different types of cancer. Nonetheless, the usage of Indocyanine green has not been fully implemented due to the heterogeneous results found in published studies. Thus, the objective of this meta-analysis is to evaluate the overall performance of Indocyanine green for sentinel lymph node mapping and node metastasis in patients undergoing colorectal cancer surgery.

METHODS

An extensive systematic search was performed to identify relevant studies in English and Spanish with no time limit restrictions. For the meta-analysis, a hierarchical summary receiver operating characteristic curve (HSROCs) was constructed, and quantitative data synthesis was performed using random effects models. Specificity, sensitivity, positive, and negative likelihood ratios were obtained from the corresponding HSROC. Between-study heterogeneity was visually evaluated using Galbraith plot, and publication bias was quantified using Deeks' method.

RESULTS

A total of 11 studies were included for analysis. The pooled detection rate for sentinel lymph node mapping was 91% (80-98%). Covariates significantly influencing the pooled detection rate were having colon cancer (estimate: 1.3001; 1.114 to 1.486; p < 0.001) and the usage of a laparoscopic approach (estimate: 1.3495; 1.1029 to 1.5961; p < 0.001). The performance of Indocyanine green for the detection of metastatic lymph nodes yielded an area under the roc curve of 66.5%, sensitivity of 64.3% (51-76%), and specificity of 65% (36-85%).

CONCLUSIONS

Indocyanine green for the detection of sentinel lymph node mapping demonstrates better accuracy when used in colonic cancer and by a laparoscopic approach. Nevertheless, its overall performance for the detection of lymph node metastasis is poor.

[Fluorescence-guided detection of lymph node metastases of gastrointestinal tumors]

A correct lymph node (LN) staging is essential in oncological surgery. Indocyanine green (ICG) near-infrared fluorescence (NIRF) guided sentinel lymph node (SLN) navigation is a relatively novel technique. The aim of this review is to analyze the impact of ICG-NIRF on identification of LN metastases of gastrointestinal tumors. The Scopus and PubMed/MEDLINE literature databases were searched and 20 studies were included. The ICG-NIRF navigation of LN has been shown to enable and improve LN detection in gastrointestinal tumors; however, the mean detection, sensitivity, accuracy and false negative rates show substantial variation. This could be due to both the heterogeneous techniques applied and to the low retention of ICG by lymph nodes. Fluorescence imaging to identify LN drainage is a promising tool to improve oncological outcomes. Nonetheless, the technique requires further development in terms of hardware, software and fluorophores, which are currently being investigated.

Near-infrared fluorescence imaging for sentinel lymph node identification in colon cancer: a prospective single-center study and systematic review with meta-analysis

Background

Near-infrared (NIR) fluorescence imaging has the potential to overcome the current drawbacks of sentinel lymph node mapping (SLNM) in colon cancer. Our aim was to provide an overview of current SLNM performance and of factors influencing successful sentinel lymph node (SLN) identification using NIR fluorescence imaging in colon cancer.

Methods

A systematic review and meta-analysis was conducted to identify currently used methods and results. Additionally, we performed a single-center study using indocyanine green (ICG) as SLNM dye in colon cancer patients scheduled for a laparoscopic colectomy. SLNs were analyzed with conventional hematoxylin-and-eosin staining and additionally with serial sectioning and immunohistochemistry (extended histopathological assessment). A true-positive procedure was defined as a tumor-positive SLN either by conventional hematoxylin-and-eosin staining or by extended histopathological assessment, independently of regional lymph node status. SLN procedures were determined to be true negatives if SLNs and regional lymph nodes revealed no metastases after conventional and advanced histopathology. SLN procedures yielding tumor-negative SLNs in combination with tumor-positive regional lymph nodes were classified as false negatives. Sensitivity, negative predictive value and detection rate were calculated.

Results

This systematic review and meta-analysis included 8 studies describing 227 SLN procedures. A pooled sensitivity of 0.63 (95% CI 0.51–0.74), negative predictive value 0.81 (95% CI 0.73–0.86) and detection rate of 0.94 (95% CI 0.85–0.97) were found. Upstaging as a result of extended histopathological assessment was 0.15 (95% CI 0.07–0.25). In our single-center study, we included 30 patients. Five false-negative SLNs were identified, resulting in a sensitivity of 44% and negative predictive value of 80%, with a detection rate of 89.7%. Eight patients had lymph node metastases, in three cases detected after extended pathological assessment, resulting in an upstaging of 13% (3 of 23 patients with negative nodes by conventional hematoxylin and eosin staining).

Conclusions

Several anatomical and technical difficulties make SLNM with NIR fluorescence imaging in colon cancer particularly challenging when compared to other types of cancer. As a consequence, reports of SLNM accuracy vary widely. Future studies should try to standardize the SLNM procedure and focus on early-stage colon tumors, validation of tracer composition, injection mode and improvement of real-time optical guidance.

Electronic supplementary material

The online version of this article (10.1007/s10151-019-02107-6) contains supplementary material, which is available to authorized users.

How robotics is changing and will change the field of colorectal surgery

During the last decade there has been a significant upward trend in colon and rectal minimally invasive surgery which can be attributed largely to the acceptance of robotic surgery platforms such as the da Vinci^® robotic system. The fourth generation da Vinci^® system, introduced in 2014, includes integrated table motion, intelligent laser targeted docking and more sophisticated instrumentation and imaging. These developments have enabled more surgeons to efficiently and safely perform multi-quadrant operations. Firefly^® technology allows assessment of colon perfusion and identification of ureters, and has shown potential in detecting occult recurrence or metastasis using molecular-labelled tumor markers. Wristed instrumentation has increased the technical ease of intracorporeal anastomosis (ICA) for many surgeons, leading to more common use of ICA during right colectomy. Advanced imaging has shown potential to decrease the incidence of presacral nerve injury and improve urogenital outcomes after pelvic surgery, as has been the case in robotic urologic procedures. Finally, the robotic platform lends itself to surgical simulation for surgical trainees, as a pre-operative tool for mock operations and as an ongoing assessment tool for established colorectal surgeons. Given these advantages, surgeons should anticipate continued and increased utilization of this beneficial technology.

Application of indocyanine green-enhanced near-infrared fluorescence-guided imaging in laparoscopic lateral pelvic lymph node dissection for middle-low rectal cancer

BACKGROUND

As one effective treatment for lateral pelvic lymph node (LPLN) metastasis (LPNM), laparoscopic LPLN dissection (LPND) is limited due to the complicated anatomy of the pelvic sidewall and various complications after surgery. With regard to improving the accuracy and completeness of LPND as well as safety, we tried an innovative method using indocyanine green (ICG) visualized with a near-infrared (NIR) camera system to guide the detection of LPLNs in patients with middle-low rectal cancer.

AIM

To investigate whether ICG-enhanced NIR fluorescence-guided imaging is a better technique for LPND in patients with rectal cancer.

METHODS

A total of 42 middle-low rectal cancer patients with clinical LPNM who underwent total mesorectal excision (TME) and LPND between October 2017 and March 2019 at our institution were assessed and divided into an ICG group and a non-ICG group. Clinical characteristics, operative outcomes, pathological outcomes, and postoperative complication information were compared and analysed between the two groups.

RESULTS

Compared to the non-ICG group, the ICG group had significantly lower intraoperative blood loss (55.8 ± 37.5 mL vs 108.0 ± 52.7 mL, P = 0.003) and a significantly larger number of LPLNs harvested (11.5 ± 5.9 vs 7.1 ± 4.8, P = 0.017). The LPLNs of two patients in the non-IVG group were residual during LPND. In addition, no significant difference was found in terms of LPND, LPNM, operative time, conversion to laparotomy, preoperative complication, or hospital stay (P > 0.05).

CONCLUSION

ICG-enhanced NIR fluorescence-guided imaging could be a feasible and convenient technique to guide LPND because it could bring specific advantages regarding the accuracy and completeness of surgery as well as safety.

Intraoperative Sentinel Node Mapping in the Colon: Potential and Pitfalls

Sentinel lymph node mapping (SLNM) may play a significant role in future delivery of colon cancer surgery because of an increase in early-stage, node-negative disease due to national bowel cancer screening programmes. Traditionally, colon lymphatic drainage has not been thought relevant as the operative approach cannot be tailored. Recent advances in local and endoscopic risk-reducing interventions for colonic malignancy have caused a rethink in approach. SLNM was initially attempted with blue dye techniques with limited success. Technological improvement has allowed surgeons to use near-infrared (NIR) light and NIR active tracers such as indocyanine green. This review provides an overview of the current status of intraoperative lymph node mapping in the colon, identifies challenges to the delivery of the techniques, and discusses potential solutions that may help SLNM play a role in improving the delivery of surgical care for patients with colon cancer.

Near-Infrared Fluorescent Rosol Dye Tailored toward Lymphatic Mapping Applications

An optical molecular imaging contrast agent that is tailored toward lymphatic mapping techniques implementing near-infrared (NIR) fluorescence image-guided navigation in the planning and surgical treatment of cancers would significantly aid in enabling the real-time visualization of the potential metastatic tumor-draining lymph node(s) for their needed surgical biopsy and/or removal, thereby ensuring unmissed disease to prevent recurrence and improve patient survival rates. Here, the development of the first NIR fluorescent rosol dye (THQ-Rosol) tailored to overcome the limitations arising from the suboptimal properties of the generic molecular fluorescent dyes commonly used for such applications is described. In developing THQ-Rosol, we prepared a progressive series of torsionally restrictive N-substituted non-NIR fluorescent rosol dyes based on density functional theory (DFT) calculations, wherein we discerned high correlations amongst their calculated energetics, modeled N-C3' torsion angles, and evaluated properties. We leveraged these strong relationships to rationally design THQ-Rosol, wherein DFT calculations inspired an innovative approach and synthetic strategy to afford an uncharged xanthene core-based scaffold/molecular platform with an aptly elevated p Ka value alongside NIR fluorescence emission (ca.700-900 nm). THQ-Rosol exhibited 710 nm NIR fluorescence emission, a 160 nm Stokes shift, robust photostability, and an aptly elevated p Ka value (5.85) for affording pH-insensitivity and optimal contrast upon designed use. We demonstrated the efficacy of THQ-Rosol for lymphatic mapping with in vitro and in vivo studies, wherein it revealed timely tumor drainage and afforded definitive lymph node visualization upon its administration and accumulation. THQ-Rosol serves as a proof-of-concept for the effective tailoring of an uncharged xanthene core-based scaffold/molecular platform toward a specific imaging application using rational design.

Doxorubicin-loaded protease-activated near-infrared fluorescent polymeric nanoparticles for imaging and therapy of cancer

INTRODUCTION

Despite significant progress in the field of oncology, cancer remains one of the leading causes of death. Chemotherapy is one of the most common treatment options for cancer patients but is well known to result in off-target toxicity. Theranostic nanomedicines that integrate diagnostic and therapeutic functions within an all-in-one platform can increase tumor selectivity for more effective chemotherapy and aid in diagnosis and monitoring of therapeutic responses.

MATERIAL AND METHODS

In this work, theranostic nanoparticles were synthesized with commonly used biocompatible and biodegradable polymers and used as cancer contrast and therapeutic agents for optical imaging and treatment of breast cancer. These core-shell nanoparticles were prepared by nanoprecipitation of blends of the biodegradable and biocompatible amphiphilic copolymers poly(lactic-co-glycolic acid)-b-poly-l-lysine and poly(lactic acid)-b-poly(ethylene glycol). Poly-l-lysine in the first copolymer was covalently decorated with near-infrared fluorescent Alexa Fluor 750 molecules.

RESULTS

The spherical nanoparticles had an average size of 60-80 nm. The chemotherapeutic drug doxorubicin was encapsulated in the core of nanoparticles at a loading of 3% (w:w) and controllably released over a period of 30 days. A 33-fold increase in near-infrared fluorescence, mediated by protease-mediated cleavage of the Alexa Fluor 750-labeled poly-l-lysine on the surface of the nanoparticles, was observed upon interaction with the model protease trypsin. The cytocompatibility of drug-free nanoparticles and growth inhibition of drug-loaded nanoparticles on MDA-MB-231 breast cancer cells were investigated with a luminescence cell-viability assay. Drug-free nanoparticles were found to cause minimal toxicity, even at high concentrations (0.2-2,000 µg/mL), while doxorubicin-loaded nanoparticles significantly reduced cell viability at drug concentrations >10 µM. Finally, the interaction of the nanoparticles with breast cancer cells was studied utilizing fluorescence microscopy, demonstrating the potential of the nanoparticles to act as near-infrared fluorescence optical imaging agents and drug-delivery carriers.

CONCLUSION

Doxorubicin-loaded, enzymatically activatable nanoparticles of less than 100 nm were prepared successfully by nanoprecipitation of copolymer blends. These nanoparticles were found to be suitable as controlled drug delivery systems and contrast agents for imaging of cancer cells.

Near-Infrared Dye-Labeled Anti-Prostate Stem Cell Antigen Minibody Enables Real-Time Fluorescence Imaging and Targeted Surgery in Translational Mouse Models

PURPOSE

The inability to intraoperatively distinguish primary tumor, as well as lymphatic spread, increases the probability of positive surgical margins, tumor recurrence, and surgical toxicity. The goal of this study was to develop a tumor-specific optical probe for real-time fluorescence-guided surgery.

EXPERIMENTAL DESIGN

A humanized antibody fragment against PSCA (A11 minibody, A11 Mb) was conjugated with a near-infrared fluorophore, IRDye800CW. The integrity and binding of the probe to PSCA were confirmed by gel electrophoresis, size-exclusion chromatography, and flow cytometry, respectively. The ability of the probe to detect tumor-infiltrated lymph nodes and metastatic lesions was evaluated in 2 xenograft models, as well as in transgenic mice expressing human PSCA (hPSCA). An invasive intramuscular model was utilized to evaluate the efficacy of the A11 Mb-IRDye800CW-guided surgery.

RESULTS

A11 Mb was successfully conjugated with IRDye800CW and retained specific binding to PSCA. In vivo imaging showed maximal signal-to-background ratios at 48 hours. The A11 Mb-IRDye800CW specifically detected PSCA-positive primary tumors, tumor-infiltrated lymph nodes, and distant metastases with high contrast. Fluorescence guidance facilitated more complete tumor resection, reduced tumor recurrence, and improved overall survival, compared with conventional white light surgery. The probe successfully identified primary orthotopic tumors and metastatic lesions in hPSCA transgenic mice.

CONCLUSIONS

Real-time fluorescence image-guided surgery with A11 Mb-IRDye800CW enabled detection of lymph node metastases and positive surgical margins, facilitated more complete tumor removal, and improved survival, compared with white light surgery. These results may be translatable into clinical practice to improve surgical and patient outcomes.

Near infrared fluorescence light imaging for lymphatic flow toward para-aortic lymph node from the Calot's triangle: A prospective exploratory study

BACKGROUND

Metastasis to para-aortic lymph nodes (PAN) in hilar malignancies is considered distant metastasis. Fluorescence imaging using near infrared fluorescence light and indocyanine green (ICG-NIR imaging) are widely employed for identifying the sentinel lymph node, which might be an ideal alternative procedure for whole excisional biopsy of PAN. However, there has been no report about ICG-NIR imaging in hilar malignancies. The purpose of this study was to determine the optimal dose for indocyanine green to detect PAN and to reveal the detection rate of ICG-NIR imaging for lymphatic flow toward regional lymph nodes (RLN) or PAN from the Calot's triangle.

PATIENTS AND METHODS

We enrolled 62 patients with hepato-pancreatic-biliary malignancies in this study. The dose of ICG was optimized in the first 15 patients and the detection rate for RLN and PAN was evaluated in the remaining 47. We observed that the optimal administered dose of ICG for detecting fluorescent signals in PAN was 5 mg/mL.

RESULTS

Using this dose, RLN and PAN fluorescence were detected in 29 of 42 patients. Fluorescent signals were recorded in the lymph nodes (LN) along the bile duct and the posterior surface of the head of the pancreas. We also detected PAN fluorescent signals on the right side of the aorta around the left renal vein. We recommend 5 mg/ml of ICG to visualize lymphatic flow from the hepatoduodenal ligament to PAN using ICG-NIR imaging. However, because detection rate of RLN and PAN were 69%, respectively, further improvement for this procedure will be necessary for clinical application.

A practical guide for the use of indocyanine green and methylene blue in fluorescence-guided abdominal surgery

Near-infrared (NIR) fluorescence imaging is gaining clinical acceptance over the last years and has been used for detection of lymph nodes, several tumor types, vital structures and tissue perfusion. This review focuses on NIR fluorescence imaging with indocyanine green and methylene blue for different clinical applications in abdominal surgery with an emphasis on oncology, based on a systematic literature search. Furthermore, practical information on doses, injection times, and intraoperative use are provided.