Near-infrared fluorescence imaging-guided lymphatic mapping in thoracic esophageal cancer surgery

The role of ICG NIRL fluorescence imaging in the surgical treatment of digestive system tumors (Review)

Indocyanine green (ICG) is a relatively non‑toxic fluorescent dye with a history of safe use, which has fueled the development of new applications for ICG. Research on the use of ICG near‑infrared light (NIRL) fluorescence imaging during oncologic surgery has increased, revealing its role in tumor identification and localization, lymph node navigational resection and blood perfusion assessment. The purpose of the present review was to provide a comprehensive overview of advances in the clinical application of ICG NIRL fluorescence imaging during gastrointestinal tumor surgery. The present review discusses the techniques, outcomes, limitations and key considerations necessary for clinical practice, aiming to provide a valuable resource for professionals in the field.

The use of indocyanine green and near-infrared fluorescence in the detection of metastatic lymph nodes during oesophageal and gastric cancer resection: a systematic review and meta-analysis

BACKGROUND

Lymph node status is one of the most important prognosticating factors for patients afflicted by oesophageal cancer (OC) and gastric cancer (GC), and lymphadenectomy during surgery is therefore an essential step to ensure complete oncological resection and accurate disease staging. Intraoperative lymph node visualisation using near-infrared fluorescence (NIRF) and indocyanine green (ICG) tracing has been postulated to improve the overall lymph node yield, and to ensure the appropriate radicality, but its usefulness in the detection of metastatic lymph nodes remains unclear.

METHODS

We conducted a systematic review and meta-analysis of the relevant literature to ascertain the accuracy of ICG-guided lymphadenectomy in the detection of metastatic nodes in OC and GC. The primary outcomes were the sensitivity, specificity and diagnostic odds ratio of ICG-guided lymphadenectomy. Secondary outcomes included measurement of the effect of prior neoadjuvant chemotherapy (NAC), tumour characteristics and method of ICG administration. Summary receiver operator characteristic (SROC) curves were built to illustrate the relationship between the sensitivity of ICG and false positive rate.

RESULTS

From an initial search of 6,302 articles, 15 studies met the criteria for inclusion, incorporating 4,004 patients. The pooled sensitivity for metastatic node detection was 69.1% (95% CI 56.5-79.3%), specificity 47.4% (38.0-56.9%), and DOR 2.02 (1.40-2.92). The SROC curve for diagnostic test accuracy yielded an area under the curve of 0.60. The use of NAC adversely affected the sensitivity of ICG 74.7% [59.2-85.8%] without NAC; 52.8% [43.6-61.9%] with NAC, p = 0.018). No significant difference in efficacy was demonstrated between pathological 'T' stage, or ICG administration method.

CONCLUSION

Our findings suggest that the oncological benefits of NIRF and ICG in the context of lymphadenectomy in OC and GC are limited, and that surgeons risk omitting a significant proportion of metastatic nodes if this technique is solely relied upon.

Evaluating Variations in Indocyanine Green Administration and Its Impact on Nodal Yield in Oesophagogastric Cancer Surgery

BACKGROUND

Indocyanine green (ICG), a near-infrared fluorescent dye, has the potential to improve oncological outcomes by increasing lymph node yield in oesophagogastric (OG) cancer. There is no consensus regarding the dose, timing, and method of injection. This study was designed to evaluate the variation in ICG administration and its potential impact on nodal yield in OG cancer surgery for the purpose of translation in Western patients.

METHODS

A systematic review and meta-analysis were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The primary outcome of this review was nodal yield, and the secondary outcome was the diagnostic accuracy of ICG in detecting metastatic lymph nodes. A meta-analysis of diagnostic accuracy data was performed by using a random-effects model.

RESULTS

A total of 38 studies (12,138 patients) were included in the analysis. Nodal yield was significantly increased in the ICG groups by 7.6 nodes (95% confidence interval [CI] 5.9-9.4; P = 0.0001) compared with control. Trends towards greater nodal yield were observed when ICG was administered at doses less than 2.75 mg, on the day before surgery, and via subserosal injection, although these did not reach statistical significance. Of the 17 studies with diagnostic accuracy data, the pooled sensitivity and specificity of ICG were 0.81 (95% CI 0.67-0.90) and 0.41 (95% CI 0.29-0.53), I2 90.5%.

CONCLUSIONS

Indocyanine green-assisted lymphadenectomy significantly increased lymph node yield, which may translate into improved survival in patients with OG cancer. The ICG dose, timing, and method of injection warrant standardisation to maximise its potential benefits in Western patients.

Progress of fluorescence imaging in lymph node dissection surgery for prostate and bladder cancer

Fluorescence imaging is a relatively new imaging method used to visualize different tissue structures to help guide intraoperative operations, which has potential advantages with high sensitivity and contrast compared to conventional imaging. In this work, we review fluorescent contrast agents and devices used for lymphatic system imaging. Indocyanine green is the most widely utilized due to its high sensitivity, specificity, low background fluorescence, and safety profile. In prostate and bladder cancer lymph node dissection, the complex lymphatic drainage can result in missed metastatic nodes and extensive dissection increases the risk of complications like lymphocele, presenting a significant challenge for urologists. Fluorescence-guided sentinel lymph node dissection facilitates precise tumor staging. The combination of fluorescence and radiographic imaging improves the accuracy of lymph node staging. Multimodal imaging presents new potential for precisely identifying metastatic pelvic lymph nodes.

Comparison of Postoperative Outcomes Between Near-Infrared Fluorescent Imaging-Guided Mediastinal Lymphadenectomy and Conventional Surgery for Esophageal Cancer

BACKGROUND

The study aimed to evaluate the efficacy of using near-infrared fluorescent imaging (NIRF) imaging with indocyanine green as an intraoperative tool for achieving complete mediastinal lymph node (LN) resection.

PATIENTS AND METHODS

Between September 2019 and July 2021, patients with potential for esophagectomy due to middle and lower thoracic esophageal cancer were enrolled in this study. All patients were scheduled for NIRF-guided mediastinal lymphadenectomy during esophageal cancer surgery and were appropriately assigned to the NIRF group. Patients who underwent esophagectomy between September 2017 and September 2019 were assigned to the historical control group upon satisfying the inclusion/exclusion criteria. Surgical outcomes and the number of removed LNs were compared between the two groups using 1:1 propensity score matching.

RESULTS

Of 67 eligible patients, 59 patients were included in the NIRF group after postsurgical exclusions. The operative time was significantly shorter in the NIRF group than in the historical control group [180 (140-420) min versus 202 (137-338) min; P < 0.001]. The incidence of postoperative chylothorax and hoarseness were significantly lower in the NIRF group than in the historical control group (0% versus 10.2 %; P = 0.036, 3.4% versus 13.6%; P = 0.047). The number of dissected total LNs, mediastinal LNs, and negative LNs was significantly larger in the NIRF group than in the historical control group. The number of overall metastatic LNs and abdominal LNs was comparable between the two groups.

CONCLUSIONS

NIRF imaging can assist in the thorough and complete mediastinal LNs dissections without increasing complications in patients undergoing esophagectomy.

Lymphatic flow mapping using near-infrared fluorescence imaging with indocyanine green helps to predict lymph node metastasis intraoperatively in patients with esophageal or esophagogastric junction cancer not treated with neoadjuvant chemotherapy

BACKGROUND

Lymphatic flow mapping using near-infrared fluorescence (NIR) imaging with indocyanine green (ICG) has been used for the intraoperative prediction of lymph node metastasis in esophageal or esophagogastric junction cancer. However, a consistent method that yields sufficient diagnostic quality is yet to be confirmed. This study explored the diagnostic utility of our newly established lymphatic flow mapping protocol for predicting lymph node metastasis in patients with esophageal or esophagogastric junction cancer.

METHODS

We injected 0.5 mL of ICG (500 μg/mL) into the submucosal layer at four peritumoral points on the day before surgery for 54 patients. We performed lymphatic flow mapping intraoperatively using NIR imaging. After determining the NIR status and presence of metastases, evaluable lymph node stations on in vivo imaging and all resected lymph nodes were divided into four categories: ICG+meta+ (true positive), ICG+meta- (false positive), ICG-meta+ (false negative), and ICG-meta- (true negative).

RESULTS

The distribution of ICG+ and meta+ lymph node stations differed according to the primary tumor site. Sensitivity and specificity for predicting meta+ lymph nodes among ICG+ ones were 50% (95% CI 41-59%) and 75% (73-76%), respectively. Predicting meta+ lymph node stations among ICG+ stations improved these values to 66% (54-77%) and 77% (74-79%), respectively. Undergoing neoadjuvant chemotherapy was an independent risk factor for having meta+ lymph nodes with false-negative diagnoses (odds ratio 4.82; 95% CI 1.28-18.19). The sensitivity of our technique for predicting meta+ lymph nodes and meta+ lymph node stations in patients who did not undergo neoadjuvant chemotherapy was 79% (63-90%) and 83% (61-94%), respectively.

CONCLUSION

Our protocol potentially helps to predict lymph node metastasis intraoperatively in patients with esophageal or esophagogastric junction cancer undergoing esophagectomy who did not undergo neoadjuvant chemotherapy.

Application of indocyanine green-mediated fluorescence molecular imaging technology in liver tumors resection: a systematic review and meta-analysis

Background

This meta-analysis was dedicated to evaluating the safety and effectiveness of indocyanine green (ICG) -mediated fluorescence molecular imaging (FMI) technology in liver tumors resection.

Methods

A literature search of PubMed, Embase databases, Cochrane Library, and Web of Science was performed to identify all clinical controlled studies exploring the effects of fluorescence imaging on liver tumors resection. Quality assessment and data extraction of studies were conducted independently by 3 reviewers. Mean difference (MD) and odds ratio (OR) with 95% confidence interval (CI) were calculated using a fixed-effects or random-effects model. The meta-analysis was performed with RevMan 5.3 software.

Results

14 retrospective cohort studies (RCSs) involving a total of 1227 patients were finally included. The results showed that Fluorescence-assisted liver tumors resection could improve the R0 resection rate (OR = 2.63; 95% CI: 1.46~4.73, p = 0.001), reduce overall complications (OR = 0.66; 95% CI: 0.44~0.97, p = 0.04), biliary fistula (OR = 0.20; 95% CI: 0.05~0.77, p = 0.02), intraoperative blood loss (MD = -70.76, 95% CI: -106.11 to -35.41; p < 0.0001), and shortens hospital stay (MD = -1.41, 95% CI: -1.90 to -0.92; p < 0.00001). There were no significant differences in the incidences of operative time (MD = -8.68, 95% CI: -18.59 to -1.22; p = 0.09), complications of grade III or above (OR = 0.73; 95% CI: 0.43~1.25, p = 0.26), liver failure (OR = 0.86; 95% CI: 0.39~1.89, p = 0.71), and blood transfusion (OR = 0.66; 95% CI: 0.42~1.03, p = 0.07).

Conclusion

Current evidence suggests that ICG-mediated FMI technology could enhance the clinical effectiveness of patients with liver tumors resection and is clinically worthy of promotion.

Systematic review registration

PROSPERO, identifier CRD42022368387.

Surgical Approach to Esophagectomy Post CheckMate 577

Following the results of the CheckMate 577 trial, the Food and Drug Administration approved adjuvant immune checkpoint inhibitor therapy for patients with locally advanced esophageal cancer without a pathologic complete response following neoadjuvant chemoradiotherapy and esophagectomy. This innovation in systemic therapy has rekindled the debate around the clinical value of an extended lymphadenectomy at the time of esophagectomy. In this article, we provide a review of the oncologic principles and potential risks and benefits of extended lymphadenectomy at the time of esophagectomy with acknowledgments to current and forthcoming innovations in thoracic surgery.

Indocyanine green near-infrared imaging-guided lymph node dissection during oesophageal cancer surgery: A single-centre experience

Objective

This study aimed to investigate the feasibility of using indocyanine green (ICG) near-infrared (NIR) imaging during lymphadenectomy for oesophageal cancer.

Methods

Eighty-seven patients with primary oesophageal cancer were enrolled in this study. All the enrolled patients received an endoscopic injection of ICG between 40 min and 23 h before surgery. Nodal dissection during surgery was performed under fluorescence imaging visualisation, with the NIR signal shown in purple. ICG⁺ or ICG^- nodes were recorded station by station and were microscopically evaluated.

Results

Endoscopic peritumoral ICG injection was successfully performed in all patients. Major post-surgery complications included wound infection, pleural effusion, dysphonia, pneumonia and anastomotic fistula. No patients experienced ICG-related adverse events. A total of 2,584 lymph nodes were removed, and the mean number of lymph nodes for each patient was 29.70 ± 9.24. Most of the removed nodes (97.83%) were ICG⁺, and 3.32% of the ICG⁺ nodes were metastatic. No metastatic nodes were ICG^- or belonged to an ICG^- lymph node station. The time from ICG injection to surgery did not affect the number of harvested lymph nodes.

Conclusions

The use of ICG-NIR imaging during oesophageal cancer surgery can enhance the visualisation of lymph nodes during surgery. It is a feasible, safe and helpful technique for lymphadenectomy.

Optimal settings of near-infrared fluorescence imaging with indocyanine green for intraoperative detection of lymph node metastasis in esophageal cancer

Lymphatic flow mapping using near-infrared fluorescence (NIR) imaging with indocyanine green (ICG) has been used for intraoperative diagnosis of lymph node metastasis (LNM) in various cancers. Accurate prediction of LNM intraoperatively may allow minimization of the extent of lymphadenectomy. However, a consistent method and diagnostic ability, allowing application of NIR-guided lymphatic flow mapping to esophageal cancer (EC), have not been established due to the multidirectional and complex characteristics of lymphatic flow in the esophagus. Herein, we present a novel NIR-guided surgical technique for predicting lymph node stations potentially containing LNM in EC with high diagnostic accuracy derived from appropriately adjusting the ICG injection setting.

Fluorescent Tracers for In Vivo Imaging of Lymphatic Targets

The lymphatic system continues to gain importance in a range of conditions, and therefore, imaging of lymphatic vessels is becoming more widespread for research, diagnosis, and treatment. Fluorescent lymphatic imaging offers advantages over other methods in that it is affordable, has higher resolution, and does not require radiation exposure. However, because the lymphatic system is a one-way drainage system, the successful delivery of fluorescent tracers to lymphatic vessels represents a unique challenge. Each fluorescent tracer used for lymphatic imaging has distinct characteristics, including size, shape, charge, weight, conjugates, excitation/emission wavelength, stability, and quantum yield. These characteristics in combination with the properties of the target tissue affect the uptake of the dye into lymphatic vessels and the fluorescence quality. Here, we review the characteristics of visible wavelength and near-infrared fluorescent tracers used for in vivo lymphatic imaging and describe the various techniques used to specifically target them to lymphatic vessels for high-quality lymphatic imaging in both clinical and pre-clinical applications. We also discuss potential areas of future research to improve the lymphatic fluorescent tracer design.

Application of Indocyanine Green Enhanced Fluorescence in Esophageal Surgery: A Mini Review

Despite recent technological innovations and the development of minimally invasive surgery, esophagectomy remains an operation burdened with severe postoperative complications. Fluorescence imaging, particularly using indocyanine green (ICG), offers the ability to address a number of issues faced during esophagectomy. The three main indications for the intraoperative use of ICG during esophagectomy are visualization of conduit vascular supply, allow identification of sentinel nodes and visualization of the thoracic duct. The purpose of this mini review is to present an overview of current practice in fluorescence imaging utilizing ICG during esophagectomy, as well as to demonstrate how this technology can guide lymphadenectomy and reduce surgical morbidity such as anastomotic leaking and chylothorax.

NIR-II Navigation with an EGFR-Targeted Probe Improves Imaging Resolution and Sensitivity of Detecting Micrometastases in Esophageal Squamous Cell Carcinoma Xenograft Models

The survival rate of esophageal squamous carcinoma (ESCC) after surgical resection is estimated to be only 30.3% due to the difficulty in identifying microinfiltration and subtle metastases. In this study, we explored the value of near-infrared fluorescence in the second window (NIR-II) using an epidermal growth factor receptor (EGFR)-targeted probe (cetuximab-IR800) for the intraoperative navigation of ESCC in xenograft mouse models. Immunohistochemical results showed that EGFR was aberrantly expressed in 94.49% (120/127) of ESCC tissues and 90.63% (58/64) of metastatic lymph nodes. Western blot results demonstrated that EGFR protein was highly expressed in ESCC cell lines. Flow cytometry data revealed that cetuximab-IR800 showed a stronger binding specificity in EGFR-positive KYSE-30 cells than in A2780 control cells (P < 0.01). In vivo imaging data showed that the ratio of mean fluorescent intensity (MFI) and tumor to background (TBR) was significantly higher in KYSE-30 subcutaneous tumors with the infusion of cetuximab-IR800 than in those with the infusion of IgG1-IR800 (P < 0.05). Surgical navigation with NIR-II imaging showed that the TBR in orthotopic ESCC was significantly higher than that of NIR in the first window (NIR-I) (2.11 ± 0.46 vs 1.58 ± 0.31, P < 0.05), and NIR-II was more sensitive than NIR-I in detecting subcentimeter metastases (94.87% (37/39) vs 58.97% (23/39), P < 0.001). In conclusion, cetuximab-IR800 with high specificity for ESCC was first used in NIR-II surgical navigation. This probe showed better imaging resolution and higher sensitivity in detecting subtle metastases derived from an orthotopic ESCC model than NIR-I, which indicates that NIR-II has promise in guiding precise surgery for ESCC patients.

Intraoperative fluorescence molecular imaging accelerates the coming of precision surgery in China

Purpose

China has the largest cancer population globally. Surgery is the main choice for most solid cancer patients. Intraoperative fluorescence molecular imaging (FMI) has shown its great potential in assisting surgeons in achieving precise resection. We summarized the typical applications of intraoperative FMI and several new trends to promote the development of precision surgery.

Methods

The academic database and NIH clinical trial platform were systematically evaluated. We focused on the clinical application of intraoperative FMI in China. Special emphasis was placed on a series of typical studies with new technologies or high-level evidence. The emerging strategy of combining FMI with other modalities was also discussed.

Results

The clinical applications of clinically approved indocyanine green (ICG), methylene blue (MB), or fluorescein are on the rise in different surgical departments. Intraoperative FMI has achieved precise lesion detection, sentinel lymph node mapping, and lymphangiography for many cancers. Nerve imaging is also exploring to reduce iatrogenic injuries. Through different administration routes, these fluorescent imaging agents provided encouraging results in surgical navigation. Meanwhile, designing new cancer-specific fluorescent tracers is expected to be a promising trend to further improve the surgical outcome.

Conclusions

Intraoperative FMI is in a rapid development in China. In-depth understanding of cancer-related molecular mechanisms is necessary to achieve precision surgery. Molecular-targeted fluorescent agents and multi-modal imaging techniques might play crucial roles in the era of precision surgery.